Volume 8, No. 1 Spring 1993
Table of Contents

Safety Status, Future Explored by Directors
"Vigilance" Discussed by ASA Panel
Letters to the Editor
Danger Seen Possible from Contaminated Medical Gases
World Congress Considers Quality of Anesthesia Care
ICPAMM Session Focuses on Anesthesia Crisis Management

Safety Status, Future Explored by Directors

by E. C. Pierce, Jr., M. D.

In October at the APSF Annual Session preceding the ASA meeting, the first retreat for the Board of Directors was held, with a total of some 50 people attending. The Directors were divided into four working groups for the Morning Session and reconvened after lunch for the Plenary Session.

The First Working Group, on Education for Safety, was directed by Drs. R. Kitz and J.S. Gravenstein and considered two aspects of education, both relating to technology: What knowledge and skills in this area should we be teaching anesthesia residents and practitioners? In addition, what technologies can be used to assist the process of education and training of anesthetists? The group recommended that the APSF broaden its view of technologies to include the anesthesia environment, identify and prioritize safety issues, develop an industry/anesthesiology forum on the subject with early direction toward resident education and the ABA/ASA Training Council, and continue support in developing anesthesia simulators.

These recommendations were considered by the APSF Executive Committee in February. It was agreed that the APSF Committee on Education will take on the task of creating a curriculum on patient safety and anesthesiology to guide the teaching and evaluation of residents and anesthesiologists. In addition, the Foundation will consider the possibility of editing a textbook on anesthesia safety, primarily directed to residents. Continued support of development for anesthesia simulators was endorsed. It was recommended that manufacturers be requested to provide more than one operations manual to hospitals when their equipment is installed so that all practitioners will have an opportunity to study the manual.

National Incident Report System Considered

The Second Working Group, on Incident Reporting and Outcome Measures, was chaired by Drs. F. Cheney and D. Gaba. The group examined types of information that could be gathered, including "incident' reports of events in which there was a potential or actual impact on safety, prospective studies of patient outcome, and closed claim analyses. The latter, of course, is being well performed by the ASA Committee on Medical Liability and certainly should continue.

At the APSF Executive Committee meeting there was significant support for the establishment of a system to allow practitioners to report events, either confidentially or anonymously. The APSF should begin to undertake such a program, although it will require a large amount of work to design and implement. The goal of the system would be improved patient safety through direct feedback about events to the anesthesia community and not classic scientific investigation, per se. In addition, it should be noted that the ongoing experiment of asking for event reports through the APSF Newsletter has yielded some eight reports thus far. These have been written up and will be published under the column title 'Experience is the Best Teacher.' The Executive Committee recognized the need to strip identifiers from the reports and to discuss issues only in generic terms.

The Third Working Group, Production Pressures and Cost Containment, was chaired by Drs. R. Chilcoat and J. Cooper. It was recommended that the APSF play a role in bringing TQM concepts into anesthesia, develop programs aimed at teaching anesthetists to better manage the operating room, support programs to investigate and improve teamwork in the OR, address the issue of safety when sedation/anesthesia is administered by nonanesthetists, and enhance the involvement of anesthesia providers in hospital political processes.

The Executive Committee noted the report from the Surgical Nursing Vice President at Dr. E.C. Pierce's Hospital, the New England Deaconess, concerning success at that hospital in bringing all parties nursing, surgery, and anesthesia together in the OR for safety and efficiency improvement. Dr. Gaba indicated that his laboratory had conducted a random survey in California concerning production pressure issues. Preliminary results from the survey were presented at the recent Society for Technology in Anesthesia meeting; these pressures are felt intensely by a significant number of practitioners. Another thought was the possible formation of a .surgical patient safety foundation' which could work with the APSF. Dr. Pierce will discuss this with Dr. R. Hanlon of the American College of Surgeons. There is need for further research to elucidate the nature and effects of needs in OR teamwork.

The fourth working group, on Practice Parameters, was directed by Drs. D. Paulus and R. Caplan. At the retreat, the group recommended that the APSF consider sensitizing topics for practice parameters development, providing intellectual leadership and manpower for practice parameters development and possibly funding the development of practice parameters.

The APSF Executive Committee reaffirmed that the APSF plays only an 'intellectual' advisor role in the process of practice parameter development. The current status of the practice parameters was reviewed by the committee and potential topics for future parameters were discussed. The Executive Committee believes that the following topics should be pursued, in this order:

1. IV sedation by nonanesthetists.

2. Prevention of peripheral nerve injury.

3. Discharge criteria from the PACU.

The APSF Executive Committee will be pleased to hear other comments from APSF members, especially from Directors who attended the October Retreat. It is likely that such a retreat will be held every other year at the time of the APSF annual session.

Dr. Pierce is president of the APSF.

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"Vigilance" Discussed by ASA Panel

by David W. Edsall, M.D.

The topic of 'vigilance' was directly addressed for the first time at the 1992 ASA Annual Meeting by a panel of experts on vigilance from the anesthesia and psychology academic communities. Unfortunately, fewer than 50 people attended the informative and interesting presentations a result not unexpected due to the almost total lack of discussion of the topic in anesthesia textbooks or journals. In contrast, vigilance is one aspect of the science of human factors which has its own societies and scientific journals. Thousands of peer review articles and dozens of complete textbooks or textbook chapters address the issue of vigilance. (1) The anesthesia community is becoming increasingly interested in human factors, as evident from recent review articles (2) topics of society meetings, (3) and task forces developed by the Anesthesia Patient Safety Foundation.

The origins of this panel came out of discussions about automation of the anesthesia workstation and whether this would have positive or detrimental effects on vigilance by anesthesia providers. The panel composed four speakers who addressed various aspects of the vigilance issue.

"Sustained Tension"

Joel Warm, Ph.D., Professor, Department of Psychology, University of Cincinnati, gave an introductory tutorial for those not familiar with the scientific concept of vigilance. Vigilance is sustained tension toward the occurrence of a signal to which one is expected to respond. A signal is an event to which one is to respond. For example, repetitive vital signs would be events. A vital sip in an unsafe range would be a signal. The ability to sustain attention toward the signal decreases with time and is called the vigilance decrement. This decrement has completed its deterioration in about 30 minutes time with half the deterioration occurring in 15 minutes.

The decrement in vigilance performance is measured by the detection and response to signals and is represented by the following formula: P = f (M,S,U,B,C) where P = Performance; M = Sensory Modality (i.e., visual vs. auditory signals); S = Signal Salience (i.e., volume of auditory signal); U = Stimulus Uncertainty; (i.e., where or when a signal will appear during the watch); B = Background Event Rate (i.e., frequency of vital signs, background noise levels, etc. "The more one has to look for signals, the less likely one is to detect them;'); C = Signal Complexity (the task can be either too complex or too simple, either of which will result in an increased vigilance decrement).

The classic vigilance paradigm occurs when: (1) the task is prolonged and continuous, (2) the signal is infrequent and a periodic; (3) the signal is easily recognizable; and (4) the observer's response cannot affect the future signal rate.

Central to the study of vigilance is the Signal Detection Theory where performance is measured in terms of detection of a signal (a) and the response criteria (p) used by the observer in responding to the signal. It appears that most of the decrement in vigilance over time does not come from a decrease in perception (a) but rather from a shift to a more conservative response criteria. "The signal is heard but not listened to." This lack of response may be due to many issues such as boredom, distraction, education, etc. Signal Detection Theory suggests that the human being is quite poor at detecting signals but can be quite good at decision-making once appropriate training has occurred. Therefore, training can affect vigilance. Automated devices, on the other hand, are excellent at detecting but quite poor at decision-making, especially when dealing with unique or complex signals.

Negative Factors

Vigilance is also impacted by stress, fatigue, high or low work load, emotional depression, noise, extreme temperatures, and many other stress inducing task environments which have been shown to increase the vigilance decrement.

The human short-term memory capacity is quite small five to ten items maximum lasting 15 to 20 seconds. Otherwise, the information needs to be converted to long-term memory and this generally requires mental effort. Automation can help reduce the stress of overloaded short-term memory or excessive short-term to long-term memory consolidation. Trend displays, if appropriately used, can reduce short-term memory workload and increase vigilance.

Dr. Raja Parasuraman, Ph.D., Professor of Psychology at the Catholic University of America, presented more information on the effect of automation in vigilance. Examples from the transportation industry demonstrated where automation has resulted in increased efficiency and decreased work load resulting in better performance. The paradox was that as automation becomes more effective human vigilance suffered because the Rehhood of a signal decreases. Thus, one must decide whether to use an automated system that fails very infrequently resulting in boredom, or to use a manual system where the likelihood of failure is higher but the operator is more vigilant and may be able to correct the condition.

Negative issues resulting from automation are: (1) decreased manual skills for the operator; (2) decreased human-to-human communication if the work situation requires a team approach; and (3) increased complacency as the automated system continues to enhance its performance. As reliability of an automated system increases, complacency increases. The solution may be to incorporate an unreliability factor in a controlled and safe manner. In other words, keep the human being in the loop with a certain frequency of manual and problem solving tasks. These tasks could be real or simulated events.

Some emphasis is being placed on selection of individuals who have a personality profile more suited to vigilance tasks. Clear and consistent differences in vigilance can be demonstrated between various human groups, such as male and female or introvert and extrovert personalities. However, the ability to predict which individual will perform better at the vigilance task has not yet been developed.

Recording devices, especially automatic recording devices, are an essential tool in the analysis of both signal detection and response performance. Without such tools, analysis of failed responses is extremely difficult. Recording devices are especially useful in cataloging a chronology of the events and signals providing information about event rate, signal rate, and response.

Anesthesia Targeted

Matthew Weinger, M.D., Assistant Professor, Department of Anesthesiology, University of California, San Diego, connected the previous presentations more specifically to the field of anesthesiology. Data from aviation and vehicle simulator studies suggest that drug use, including small quantities of alcohol taken within 12 hours of task performance can result in decreased performance. Extreme temperature and fatigue have also been asserted to affect performance in anesthesiology. A description of primary and secondary tasks and their use in the anesthesia environment for studying vigilance and other human factor issues was related to automated record keeping. Several studies now suggest that automated records can decrease the time spent and/or increase the amount of data gathered by the recording task.' One preliminary study suggests that vigilance seems to be increased during induction when automated records are being used." Techniques are being developed to study vigilance in the anesthesia environment with the eventual goal of enhancing the performance during high work load (stressful) conditions, as well as low work load (boring) conditions. Another preliminary study seems to indicate that graphical display of vital sign information leads to a. faster signal detection than does the numerical display of the same information.

David Gaba, M.D., Assistant Professor, Department of Anesthesiology, Stanford University, emphasized that vigilance is a necessary but not sufficient condition for appropriate clinical decision-making. It was suggested that an anesthetist may be awake and alert but because of signal complexity, high work load, distractions, or inappropriate signal display, the anesthetist may not address the correct problem."," Similarly, a problem may be detected but the response time may be slowed because of difficulty in deciding what to do about the problem. The use of an anesthesia simulator, as in the aviation industry, has been invaluable in identifying some of these issues. Preliminary simulator studies dramatically demonstrated the need for studying anesthesia human factors and vigilance problems in as realistic a setting as possible. Even the most realistic simulators have problems in this regard because the level of expectancy for problems is raised significantly when compared with the real world environment. Beyond vigilance issues of leadership, education, action planning, resource allocation, and communication are other conditions required of the anesthetist in order to provide good patient care.

Both the panel discussion and all four presenters addressed the issue of detection versus response. This issue becomes confused by the third item of the vigilance paradigm in that the signal must be easily detectable. Consider the anesthetist who does not recognize an ST segment change. Is this a vigilance problem? Certainly it could initially be an educational problem or an equipment problem. Many if not most anesthetists state that the recognition of ST segment changes or arrhythmia is not an 'easily recognizable signal' as the vigilance paradigm requires. However, for many CCRNs it can be demonstrated that " task is automatic and, therefore, becomes a vigilance task. Likewise, it might be said that the response to the signs of malignant hyperthermia is not a vigilance issue. Possibly, with appropriate training this response could also become automatic for the anesthetist. Therefore, the study of vigilance includes not only detection but also the response time. In fact, the key component in most vigilance studies is measurement of response time as opposed to the detection of a signal. Training to improve both the detection of signals and increase the response time to a critical event is what this author believes is meant by our profession's motto: 'VIGILANCE.'

Dr. Edsall is Chairman, Department of Anesthesiology, Burbank Hospital, Fitchburg, MA, and a pioneer in implementation of automated anesthesia records and information management systems.


1. Human Factors. Journal of the Human Factors Society of America, Santa Monica, CA.

2. Weinger, MB, Englund CE: Ergonomics and Human Factors affecting anesthesia vigilance and monitoring performance in the OR environment. Anesthesiolog 1990; 73:995-1002.

3. "Human Performance and Anesthesia Technology.' The Society for Technology in Anesthesia 3rd Annual Meeting, New Orleans, La. February 17-19,1993.

4. Herndon OW, Weinger MB, Zornow MH, and Gaba DM: The use of automated record keeping requires less time in complicated anesthesia procedures. Anesth Analg 1992; 76:S140.

5. Edsall DW: Documentation time requirement: Computerized information management Systems versus handwritten records. Anesthesiology 1990; 73(3A):A439. (Full paper in press)

6. Kennedy PJ, Feingold A, Wiener, EL, et al: Analysis of tasks and human factors in anesthesia for coronary artery bypass. Anesth Analg 1976; 55:374-377.

7. Zollinger RM, Kreul JF, and Schneider AJL: Manmade versus computer-generated anesthesia records. Surg Res 1977; 22:419-424.

8. Lerou JGC, Dirksen R, vanDaele M., et al: Automated charting and physiological variables in anesthesia: a quantitative comparison of automated versus handwritten anesthesia records. J Clin Monit 1988; 4 (1):37-47.

9. Dirksen R, et al: The clinical use of the Ohmeda automated anesthesia record keeper integrated in the Modulus E anesthesia system. Int j Clin Mon Comp 1987; 4:135-139.

10. Weinger MB, Herndon OW, Paulus MP, Gaba DM, and Dallen LD: Objective analysis of performance workload in the anesthesia cockpit. J Clin Monit 1992; 8:186-187 (Abstract).

11. Gaba DM: Dynamic decision making in anesthesiology realistic simulation for anesthesia crisis management training. Advanced Models of Cognition for Medical Training and Practice, edited by Evans DA and Patel VL. Springer-Verlag, GmbH.

12. Howard SK, Gaba DM, Fish KJ, Yang GS, and Sarnquist FH: Anesthesia crisis resource management training. Aviation, Space, and Environmental Medicine.

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Letter to the Editor:

Pulmonary Edema After Appendectomies Poses Puzzle

To the Editor

We would greatly appreciate any expert commentary on a distressing situation we have encountered in our practice. At the very least, we would like to know whether we are unique in our problem or whether others have had similar experience.

Over the past five years we have had six patients who underwent uneventful appendectomy under general anesthesia (extubated in the operating room), all of whom developed bilateral pulmonary edema within five minutes of arrival in the FACU. All cases were that of supportive appendicitis, only one being perforated. All patients were young (14-35 years old), febrile, and of ASA physical status I or U. Oxygen saturations during the case were easily maintained during positive pressure ventilation. Upon arrival in the PACU, all patients demonstrated tachypnea but without complaint of dyspnea, a wet cough productive of pinkish froth, and oxygen saturations of 75-80% on room air (confirmed by arterial blood gas) without cyanosis of lips or nailbeds. Oxygen saturations could be maintained in the high 80's to low 90's only with supplementary oxygen. Rales were evident on exam and chest radiograph confirmed bilateral pulmonary edema. None required reintubation.

The quantity of pulmonary edema generally increased over the next 30 minutes and then stabilized. The presence of rales persisted for 48 hours; however, the gross production of edema fluid subsided after about six hours. Pulmonary shunting persisted even longer as evidenced by a continued supplementary oxygen requirement which was still present for as long as three to five days following surgery.

A New Development?

Prior to 1987, this situation was unknown at our institution according to our more senior anesthesiologists and surgeons. Indeed, our department of six board certified anesthesiologists (four of whom have been involved with the above incidents) has a collective experience of 60 years and no one recalls this sort of outcome following appendectomy in the past.

Needless to say, we have discussed these cases in detail as part of our quality assurance process. Possible causes such as drug-induced anaphylaxis, negative pressure pulmonary edema, aspiration, sepsis, contaminated intravenous solutions (tested negative on one occasion), and even latex allergy have been discussed and invoked at one time or another without certainty.

The duration of the pulmonary edema and shunting argue against the first two mentioned causes. Aspiration seems unlikely as well, unless it was massive because of the abrupt bilateral onset of the edema. Naloxone was not used in any of the cases. I feel strongly (unlike our internists) that a cardiogenic etiology is unlikely considering the preoperative health and age of our patients.

Then what is causing this? More frequent use of latex gloves in recent years? About five years ago we started giving preoperative antibiotics in suspected cases of appendicitis. Are we dealing with a Schwartzman-like reaction? Whatever the cause, why is it evident upon arrival in the PACU? Is it because positive pressure ventilation has been discontinued which has prevented transduction of fluid through a leaky pulmonary vasculature?

A search of the literature has not been fruitful. Only one citation could be found discussing two patients with appendicitis;' however, the pulmonary edema could have been due to a myocardial process. Cooperman and Price' described 40 cases of postoperative pulmonary edema, but none was in the setting of appendicitis. Latex allergy has also been implicated in intraoperative anaphylaxis. (3) To date, we have been unable to identify an etiologic factor(s) in these cases of pulmonary edema.

We would greatly appreciate any thoughts and comments.

Lowell Garner, M.D.

Department O Anesthesia

Tompkins Community Hospital Ithaca, NY


1. Eldor J, Fisher J, Shir Y, and Pizov R. Postoperative pulmonary edema diagnosed in the recovery room (letter). Resuscitation 1990; 20:&3 85.

2. Coopeman LH and Price HL. Pulmonary edema in the operative and postoperative period: a review of 40 cases. Ann Surg 1970; 172:8&M91.

3. Cold MG, Sovartz JS, Braude BM, Dolovich J, Shandiing B, and Gilmore RF. Intraoperative anaphylaxis. J Allergy Clin Immunol 1991; 87:662-666.

Recovering CRNA Disputes Writer's Idea that Past Abusers Should be Feared, Identified

To the Editor

I would like to respond to Mary Locke's letter in the winter APSF Newsletter, concerning substance abusers "being allowed to continue to administer anesthetics...". As a recovering alcoholic and an active member in A.A., I have a vested interest in this ethical realm. It is necessary to make the distinction between an active abuser and a recovering substance abuser.

I agree with Ms. Locke that an anesthetist who is actively using any controlled substances should not be allowed to administer anesthesia. If any staff member exhibits suspicious behavior which might indicate he or she is currently using these drugs, they should be promptly confronted by someone in authority, submit to drug screens and required to attend rehab. Yes, every group or hospital should have a strict policy, that continued employment depends on random checks upon their return and remaining drug free.

Alcohol can be as potent a depressant as opiates, barbiturates, and benzodiazepines, yet in the same issue, it was reported that Dr. Hendon of the University of California at San Diego presented data that 75% of the 85 subjects in his questionnaires drank alcohol on a regular basis. Because alcohol is legal and widely used, the OR doesn't dose the day after the Christmas party or other social functions, when many are undoubtedly hung over or have consumed alcohol within 12 hours of administering anesthesia.

A recovering substance abuser, from alcohol, drugs or both, has NO mind altering substances in their system whatsoever, and is therefore more mentally dear than someone who has used any of these recently. To include identification of an anesthesia provider as a recovering substance abuser on the consent form, per Ms. Locke's suggestion, is sheer nonsense. The patient doesn't have to fear the former substance abuser, but rather the anesthetist who is currently "using.'

I regret that, for obvious reasons, I must remain anonymous, but I hope this won't preclude my letter being printed. [Editor's note: Under usual circumstances, anonymous letters will not be considered. The nature of this comment on the important issue of the relation of substance abuse among anesthetists to anesthesia patient safety prompted this exception.]



OR Noise a Problem; Standards Sought

To the Editor

I would like to recommend that the APSF encourage the establishment of standards for noise levels in the OR.

Common sense would dictate that excessive extraneous noise is a detriment to safe anesthesia care. Noise impairs communication among the various anesthesia providers at critical moments of the case as well as between the anesthesia team and the surgeons or nurses; it distorts the ability to hear and interpret audible monitors. Nevertheless, many of us work in an atmosphere charged with decibels. Some of the noise is unavoidable and related to the case. Much of it consists of irrelevant conversation, joke telling, and blaring of the omnipresent stereo with "surround sound".

Attempts by individual anesthesiologists to control this hazard are usually futile or temporary at best. We need a nationally accepted standard to point to as a reference. The Association of Operating Room Nurses has established a variety of standards which conform to their view of safe patient care. We, as anesthesia providers, would be remiss in our patient-care duty to do any less.

Steven S. Kron, M.D.

New Britain Anesthesia, P.C. New Britain, CT

Need for FiO2 Monitor Strongly Defended

To the Editor

I am writing in response to the letter of Jurgen Link which appeared in Volume 7, No. 2, Summer 1992 Newsletter, page, 19. A properly functioning, correctly calibrated oxygen (FiO2) monitor is the single most important monitor in preventing hypoxia. When placed in the inspiratory limb, the oxygen analyzer can detect potential defects before they can affect a patient's oxygen saturation. Among the conditions that can be detected by FiO2 monitoring are:

* Reduction or cessation of oxygen pipeline or cylinder pressure.

* Wrong gas supplied to DISS inlet or cylinder yoke inlet.

* Hypoxic oxygen/nitrous oxide mixture set at the flowmeters.

* Oxygen flowmeter inadvertently turned down or off.

* Leak at the oxygen flowmeter. Leak in the fresh gas line. Fresh gas disconnect.

* Nitrogen accumulation.

In answer to the first question, relying solely on a mechanical/optical device to mix fresh gas concentrations that are not monitored presupposes that the device is incapable of error or breakdown. I know of no such medical device which can make these claims.

In answer, to the second question, monitoring FE02 can provide useful information when compared to FiO2 readings. Use of FE02 readings alone leaves you to assume accuracy of delivered FiO2. In addition, placement of an oxygen sensor in the expiratory limb introduces potential error due to moisture condensation on the sensor. This would be particularly true for long procedures or when used with heated humidification systems.

Another option to the oxygen monitor vs. pulse oximeter question would be the use of paramagnetic sensors for the FiO2 monitor. After the initial purchase, maintenance costs would be minimal or non existent.

Wes Simpson 11

Lead Anesthesia Technician, Surgical Services Division, Sharp Memorial Hospital, San Diego, CA

FiO2 Monitor Still Has Important Role

To the Editor.

I am pleased to offer the following answers to Dr. Link's stimulating educational questions, published in APSF Newsletter, Summer 1992, page 19, concerning the benefit of the 02 analyser in patients monitored with a pulse oximeter.

The so-called 02/N20 'safety mixers' do not provide the patient "under all conditions' with a gas mixture containing at least 21% 02. Their only benefits are to protect against errors in flow control settings and to act as a N2O cut-off device in case of failure of 02-supply to the machine. However, (1) a mixer does not protect against faulty interconnections, crossed pipelines, pollution of the 02 pipeline with N20 or medical air, (2) it can itself be defective and allow the development of either a hypoxic (hypoxia!) or a hyperoxic (awareness!!) gas mixture, (3) the 02 bypass linked with the mixer can be defective and allow a preferential 02 leak, i.e. the build up of a hypoxic mixture, and (4) it cannot prevent the development of a hypoxic mixture downstream in the anaesthesia breathing system, especially in case of low flow anaesthesia (consumption of 02 and/or accumulation of other gases).

The 02 analyser is essential for a swift and accurate interpretation of a hypoxic event detected by the pulse oximeter. There is indeed a long delay between the onset of a problem, such as a failure of 02 supply to the machine, and its recognition by the pulse oximeter (1) delay required for washing out the anaesthesia breathing system and the FRC (time constant), delay of lung-to-finger circulation time and the monitor response time. Therefore it may be nearly eight minutes before the pulse oximeter reading falls. Owing to the exponential type of the oxyhaemoglobin dissociation curve, the pulse oximeter provides no warning until the PaO2 has fallen below 90 mmHg. At this time the hypoxic event is already in progress and every anaesthetist would be happy to be informed without delay by the 02 analyser whether the cause is located in the anesthetic machine or in the patient. If the cause of the hypoxic event is the administration of a hypoxic gas mixture (hypoxic meaning in some cases an insufficient 02 concentration for a given patient), the 02 analyser will detect it a long time before the pulse oximeter. This is of major importance, as in the case Of 02 supply failure to the machine, an additional delay (to the still 'lost' eight minutes) is also required until enough 02 reaches again the alveoli... the brain and the finger tip!

When the 02 sensor is located in the expiratory tubing of the circle system, the analyser provides (with an additional short delay !) the same information as when located in the inspiratory tubing. Incidentally it could also act as a disconnection monitor. However in this position it is maximally exposed to water vapor with its negative effects on the sensor. Moreover 02 analysers with slow response time (> 10 s) such as polarographic or galvanic (fuel cell) techniques, monitor only a trend, which is appropriate to the inspiratory tubing location where the concentration of gases remains relatively constant. When located in the expiratory tubing, where the concentration of gases changes continuously, these devices cannot provide accurate information on the N20 washout at the end of anaesthesia. Such information is only obtained with short response time (< I s) analysers, such as paramagnetic or mass spectrometric methods. However, for these devices the optimal location is the patient limb of the Y-connection piece and not the expiratory tubing.

It can be concluded that (1) the pulse monitor is an unsurpassed monitoring tool for 02 transport to and within the patient, (2) the 02 analyser is its essential acolyte, as it increases by at least 50% the informative power of the former and eventually the patients safety, (3) one of the most noble goals of an anesthesiologist is to provide his patient with 02. The 02 analyser is the only instrument able to recognize oxygen and to measure its concentration; therefore, it is an essential device.

J.C. Otteni, M.D., FRCAnaes

Hopitaux Universitaires de Strasbourg France


1. Sykes MK, Vickers MD, Hull CJ. Principles of measurement and monitoring in anaesthesia and intensive care 3rd Ed., London: Blackwell Scientific Publications Ed., 1991, 294-295.

To the Editor

Dr. Jurgen Link asks the value of the in-line oxygen analyzer compared to pulse oximetry in the APSF Newsletter, Summer 1992. Legal consequences are not to be considered per Dr. Link.

The analysis of oxygen in the patient circuit, either the inhalation or expiration side, is essential to safe patient care in 1992. The pulse oximeter is an end-stage analyzer for many of the conditions the oxygen analyzer will pick up faster and easier. Pulse oximetry has been a great advance to patient care but it cannot and should not substitute for the presence of an oxygen analyzer.

Deaths during anesthesia are still being reported from crossed nitrous oxide and oxygen lines, (1) and incorrectly filled medical gas cylinders. (2,3) Near misses have occurred when a medical gas cylinder was filled with carbon dioxide and nitrous oxide instead of just nitrous oxide (4) and when a machinist modified the pin index of the anesthesia machine and nitrous oxide was put an the machine instead of Entonox. (5) These are only recent examples of a continuing problem in anesthesia of hypoxic gas mixtures being administered to the patient.

The oxygen analyzer can detect the wrong gas in the hospital pipeline from crossed pipelines or from wrong gas in the delivery tank. Bypasses of the pin index safety system by human intention or from filling the gas cylinder with the wrong gas can be detected early with the oxygen analyzer. The pulse oximeter must await the development of low oxygen saturation before the anesthesiologist begins to evaluate the rapidly progressing critical situation. Not many anesthesiologists would suspect the wrong gas in the oxygen tank or crossed fines as the cause of the oxygen desaturation! The patient would continue to desaturate while the anesthesiologist is frantically trying to find out the cause. Perhaps a wise anesthesiologist would switch the patient to a self-inflating reservoir bag and deliver room air until the problem is resolved. Most likely, the patient would suffer morbidity or maybe even mortality before the problem is detected.

An oxygen analyzer measures the output of the fresh gas hose in relation to the amount of oxygen delivered. The pulse oximeter measures the percent saturation of hemoglobin. It is unwise to ask either monitor to do the job of the other since they are designed for specific analysis (just like the gas gauge and oil pressure gauge on a car).

Keep both the oxygen analyzer and pulse oximeter in place and the safety of the patient will be greatly enhanced.

Clayton Petty, MD HCA St. Mark's Hospital

Salt Lake City, LIT


1. Crossed N20 & 02 lines blamed for outpatient surgery death. Biomedical Safety & Standards 22:14,1992.

2. Jawan B, Lee JH: Cardiac arrest caused by in correctly filled oxygen cylinder: A case report. Brit j Anaes 64:749,1990.

3. Menon MRB, Lett Z: Incorrectly filled cylinders (Letter). Anaesthesia 46:155,1991.

4. Nitrous oxide cylinders found to contain carbon dioxide. Biomedical Safety & Standards 20:84,1990.

5. Nonstandard user modification of gas cylinder pin indexing. Biomedical Safety & Standards, circa 1989.

On supplemental O2 During MAC

To the Editor:

Each month we care for 75-100 patients having cataract surgery under M.A.C. at our surgical center. Before we had SaO2 monitors available, we used the anesthesia circuit resting on the patient's chest to fill the space under the drapes with oxygen during surgery. This did not prevent desaturation when the patients were sedated. I placed an FiO2 monitor under the drapes near the patient's face and monitored FiO2 both with and without supplemental 02. The difference was rarely greater than 2-3%.

I decided that I would put an oxygen nasal cannula on the patient, taping it to the cheeks, well out of the surgeon's way. The improvement was dramatic and now, 2 liters/min. oxygen suffices in all but the most compromised patients. This has improved our safety, saves a lot of money and reduces the very real risk of fire with large volumes of oxygen under the drapes.

I was concerned that such a low flow of oxygen would not suffice to displace unwanted C02 from under the drapes, resulting in re-breathing. I placed the C02 monitor near the face of several patients before and after the drapes were placed. The C02 level did rise a few percentage points after the drapes were placed. I am not convinced that this does any harm.

One surgeon insists on a suction catheter under the drapes to evacuate C02, but his patients do no better than patients of the six other surgeons who do not, as far as I can tell.

Stephen R. Shuput, M.D.

Intermountain Surgical Center Salt Lake City, UT

More on FiO2 Monitor vs. Pulse Oximeter

To the Editor

In response to the letter by Jurgen Link, "What is Value of FiO2 Monitoring Compared to Pulse Oximetry?" (APSF Newsletter, Summer 1992, P.19), we would like to make the following points:

Although pulse oximetry is a valuable tool in the operating room, it is less than ideal for the detection of hypoxic gas administration for the following reasons:

1. Pulse oximetry measures the patient's response to hypoxia, whereas an oxygen analyzer allows the anesthesiologist to detect a low FiO2 before the patient is affected.

2. Pulse oximetry is very non-specific, and hypoxic gas delivery (as can occur with pipeline cross-connections of misfilled cylinders) is generally not the first thing one thinks of when the SpO2 starts to decrease. A variety of factors, most of which are far more common than problems with oxygen delivery, will cause a decrease in the SpO2. These include circulatory and pulmonary pathology, mechanical problems with gas delivery (obstructed endotracheal tubes or disconnections), methmoglobinemia or intravenous dyes, and numerous sources of artifact. By the time one has ruled out the more likely causes of a decrease in SpO2 prolonged, severe hypoxia may ensue.

3. An oxygen-nitrous proportioning system will work only if there is oxygen flowing through the oxygen pipes and nitrous flowing through the nitrous pipes. Case reports in the anesthesia literature describe how pipelines may be crossed in the bulk supply system or in the anesthesia machine itself," or how cylinders can be misfilled or attached to the wrong yoke of the anesthesia machine.',' An in-line oxygen analyzer is gas specific instead of flow dependent, and can therefore identify potential disasters such as these.

Oxygen analyzers utilizing a Clark electrode are placed in the inspiratory limb because the moisture in expired gas can affect the accuracy of the monitor.

We sympathize with the financial problems, but do not believe that pulse oximetry is a replacement for oxygen analysis. Argument can be made that mass spectroscopy also being gas specific, could be a replacement, but that wouldn't help with the financial problem. We believe that both an oxygen analyzer and pulse oximetry are essential for patient safety.

Judith T. Hutchinson, M.D. Elizabeth Lee, M.D.

Department of Anesthesia

University of Maryland Medical System Baltimore, MD


1. Tingay MG, et al. Gas identity hazards and major contamination of the medical gas system of a new hospital. Anesth Intensive Care 1978; 6:202-209.

2. Arrowsmith LWM. Medical gas pipelines. Eng Med 1979; 8: 247-249.

3. Lane GA. Medical gas outlets A Hazard from interchangeable 'quick-connect' couplers. Anesthesiology 1980; 52: W87.

4. Bonsu AK, Stead AL. Accidental cross-connection of oxygen and nitrous oxide in an anesthesia machine. Anesthesiology 1982; 38: 767-769.

5. Feeley TW, et al, Potential hazards of compressed gas cylinders. Anesthesiology 1978; 48: 72-74.

6. Holland R, Foreign correspondence: Another wrong gas incident in Hong Kong. APSF Newsletter 1991; Spring P.9.

Suction Of C02 Suggested as Needed as Well as Nasal 02 During Cataract Surgery

To the Editor

I am writing in response to the letter from Doris M. Penndorf, CRNA (Volume 7, No. 2, page 19). Several years ago we purchased a similar device for delivering supplemental oxygen for our patients undergoing cataract surgery with M.A.C. Initially, we used the device in a similar fashion to Ms. Penndorf's s institution, and we had many of the same concerns. We feel we have resolved the potential dangers by the following modifications

1. Rather than using the perforated ether screen to deliver supplemental oxygen, we hook it up to low level continuous suction. This draws in room air under the drapes and effectively scavenges excess oxygen and exhaled carbon dioxide.

2. All patients receive supplemental oxygen via nasal cannula. Nasal cannula which deliver oxygen and allow for ETC02 sampling are also available for use on selected patients.

3. As part of our overall safety program, information was obtained from the manufacturers as to the flame retardant characteristics of the disposable drapes that we use.

In addition to the above modifications, the anesthesiologists routinely provide appropriate monitors throughout the procedure. These modifications have been used successfully for more than 10 years in our institution.

Wes Simpson 11

Lead Anesthesia Technician Surgical Services Division Sharp Memorial Hospital San Diego, CA

Immediate Past President

California Association of Anesthesia Technologists and Technicians

Fan Used Under Cataract Drape

To the Editor

We are stimulated to respond to a letter appearing in a recent APSF Newsletter, (1992, volume 7, page 19), entitled "Supplemental oxygen for M.A.C. cases: Is it valuable? Is it a hazard?' by D.M. Penndorf. Ms. Penndorf highlights what is indeed a problem when lightly sedated patients for ophthalmological surgery under local analgesia are placed beneath drapes. It is most uncomfortable for the patient to he totally covered in drapes and indeed hazardous unless some way of supplying oxygen and promoting carbon dioxide removal is provided. There is also, as Ms. Penndorf notes, a further potential hazard of fire due to the high oxygen concentration beneath flammable drapes.

We have gone some way toward solving these problems by the simple use of a battery operated air blower. The drapes are tented up over a light plastic moulding (an IV pole or 'ether screen' would do just as well) to which runs a tube supplying between 6 and 8 1 /min of 100% oxygen. The blower supplies room air through a one inch diameter flexible pipe resting alongside the plastic moulding at a flow rate of 3 3.5 1 /min. This reduces the Ukehhood of an excess accumulation of oxygen, enhances carbon dioxide removal, and further lessens any sense of claustrophobia by the stream of fresh cool air. Theoretically, the inspired oxygen concentration could be adjusted within limits by altering the flow rate of the supplemental oxygen and measured using a fuel cell oxygen analyser (or similar) placed near to the patient s face.

The blower which we have found to be very suitable is manufactured by Stackhouse Inc., El Segundo, California. It is compact, light in weight and operated by a rechargeable battery. It is marketed as a part of their 'Freedom Mark III' surgical helmet system. It is not expensive and can be purchased separately.

We have found this technique useful in more than 1,000 patients to date.

Brian J. Pollard, M.D

Janis Shaw, M.D.

Department of Anaesthesia

The University of Manchester ', England

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Danger Seen Possible from Contaminated Medical Gases


by Ervin Moss, M.D.

Scattered reports describing particulate matter in gas pipelines and potential bacterial contamination of medical air prompted the Anesthesia Patient Safety Foundation during its October, 1992 annual meeting to request its Committee on Technology to prepare a white paper concerning maintenance of anesthesia equipment. A subcommittee has been appointed consisting of Patrick A. Foster, M.D., Hershey Medical Center, Michael Good, M.D., University of Florida, Gainesville, and Ervin Moss, M.D., New Jersey State Society of Anesthesiologists. Their task will be the investigation, evaluation as to risk, and documentation of particulate matter in and contamination of gas lines, storage cylinders, valves, medical air dryers, and compressors. Prevention and correction of these problems would be included in any document about maintenance of anesthesia equipment.

While in recent years anesthesiologists have become aware of the mechanics of their anesthesia machines, the interfacing of monitors, and the machine to patient interface, medical gas lines (once they disappear through OR, ICU, nursery, hospital room, and emergency room walls) seem to enter a .no man's land' for which accountability is left to the hospital engineering department. Even the FDA, when approached with the early suspicion of potential problems, responded that their responsibility applied to the equipment or medical devices contained in the walls of the various locations to which the medical gases flowed.

APSF Involved

It is the intent of the APSF committee to make sure the anesthesia community is aware that particulate matter entering ventilators and anesthesia equipment can affect the functioning of such equipment. It is also the intent of the committee to open up the 'no man's land' beyond the walls so that anesthesiologists will extend their knowledge to include the anatomy of the medical gas line system starting from the machine, through the wall, through the valves, and to the source of the gas supply. Included will be the understanding of how medical air and oxygen reach all locations throughout the hospital.

Recent reports which caused the APSF to decide to explore the issue included an incident involving the malfunction of an infant ventilator due to particulate matter contamination. After the massive fire in Kuwait, almost all the medical air systems of that country were contaminated by oil. Even medical gas lines were contaminated due to cracks in pipelines caused by explosions. Another example was the removal of 30 pounds of particulate matter from the pipelines of a 700 bed hospital in the United States. Also of interest was the report from a manufacturer of medical equipment in which 20 workers on the assembly fine were sickened by noxious fumes in the compressed air used to air clean parts before assembly. The fumes were the result of oil entering the compressor during servicing. If that compressor had supplied medical air to a nursery, the toxic fumes released could have caused serious complications.

A future edition of the APSF Newsletter will feature a report on another danger of gas within the OR: particulate matter, bacteria, and fungi pumped into the abdominal cavity in contaminated C02 during laparoscopic surgery. Dr. Douglas Ott, a gynecologist from Macon, GA, will discuss the results of his research on contamination of CO2 cylinders and the physiologic changes caused by cold and dry C02.

The APSF is the only forum within anesthesiology where industry representatives and clinicians share their expertise, and a great resource of information has become available through the cooperation of members of industry who are active in the APSF. In addition, the FDA and the JCAHO are represented on the board. As projects develop, these bodies can be most helpful in implementing any suggestions that might result.

The first material relevant to this topic is presented below:

The Health of Our Piped Medical Gas Distribution Center

by Mssrs. Fred Evans and Pete Winboume

In recent years there has been a growing awareness of and concern about the relationship between medical gas pipelines and related medical equipment malfunction. This view has been shared by various experts within related fields. A recent exchange of information has led us to the conclusion that the problem warrants further study.

It is interesting to note that medical gases constitute, by volume, the most common and the most voluminous prescription drugs administered in the hospital. However, not enough attention is paid to the packaging and the delivery network.

Medical gas systems are not difficult to design or install. Difficulties arise from the fact that designers and installers have scant knowledge of how or why these systems are utilized within the hospital.

For a number of years, certain NFPA (National Fire Protection Association) recommendations were felt to address the correct design and installation of medical gas systems. While these recommendations were a start, they did not clearly address the intent of the code, especially in the area of installation procedures.

Installation is complicated to some degree by assuming the manufacturer has supplied the correct pipe, the designer was code knowledgeable, and the interpretation of the NFPA is not confused. However, in recent years, systems that were installed prior to NFPA 99, 1990 began to present new problems. Some of these compromise patient safety and care.

Prior to NFPA 99, 1990 recommendations, the pipe brazing process did not call for a procedure using an inert gas to prevent carbon oxidation within the pipe. The carbon scale deposits from the old process loosen over time and migrate toward the areas of greatest gas flow. Such particulate contamination probably constitutes the largest single source of problems within medical gas systems.

New NFPA recommendations address this issue. It then becomes a matter of proper inspection during construction. This should be an essential part of a 'Pipeline Certification Procedure.' Proper certification of a system is NOT performed at the end of installation. Many end users rely on a final pipeline certification report without reading the fine print disclaiming design, labeling, solid particulate contamination, brazing, and other major abnormalities. Prevention of problems, rather than corrections, should be the cornerstone. It then follows that proper design criteria are paramount for any medical gas system.

It is not the intent of this article to address all possible design and installation flaws. Some, however, must be mentioned. The design, " and configuration of medical air compressors create probably the second most prevalent type of problem. Moisture within the air system will result in particulate contamination and very often in growth of gram negative bacteria within the compressed air system.

When an air system has been contaminated with water, it is not a simple matter to drain and clean it; zone valve drops and other piping configurations make this extremely difficult. These areas usually act as reservoirs and support and harbor potentially infectious bacteria. For that matter, gram negative bacteria have been cultured from piped oxygen systems. How they were introduced is conjecture at this point.

If a medical air system contains any 'abnormal odor,' a proper inspection should be performed, and steps taken to correct the problem. Although no conclusive data exist, it cannot be of any benefit to administer 'contaminated air' to any patient, especially one who may be on ventilator support. These potential problems are not restricted to any particular type or make of air compressor.

New NFPA 99 recommendations will go far in correcting existing problems and if adhered to, greatly reduce patient risk. It would be well to remember also that NFPA 99 recommendations are minimum recommendations and must not be compromised. Under these new guidelines, every health care facility must institute procedures that address correction of existing pipeline problems.

Odors, particulate contaminate, copper or brass shavings, copper carbonate, iron oxide, calcium carbonate, oil, gram negative bacteria, sodium chloride, flux and other debris are all recognized contamination hazards within medical gas piping systems. Except for bacteria, it seems highly improbable that these elements could be introduced into a patient's lungs. However, they do have a demonstrated detrimental effect on equipment to which the patient is attached:

Actual Cases

1. There have been recorded instances of trichloroethane administered to a patient, which resulted from an improperly cleaned zone valve, and an improper pipeline certification.

2. One facility experienced eight adult ventilator failures due to heavy amounts of solid particulates from the gas pipeline.

3. Numerous reports of oxygen blender failures due to solid particulates.

4. An oxygen outlet in an emergency room had a reduced flow due to solid particulate obstruction.

5. An anesthesia machine malfunctioned due to heavy amounts of contaminating solids at the inlet filter.

The contamination problem is not hopeless. The systems affected do not have to be replaced, but can be properly cleaned, decontaminated, and certified by companies which perform these functions. We believe it would be prudent to begin an update program to conform to NFPA 99 and JCAHO requirements. Patients deserve no less than an uncompromised medical gas delivery system.

Dr. Moss of the New Jersey State Society of Anesthesiologists is a Director of the APSF. Mr. Fred Evans is president of Medical Gas Management, Inc., of Bethany, OK, and Mr. Pete Winbourne is director of risk management for anesthesia programs for Health Care Insurance Services of Houston, TX.

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World Congress Considers Quality of Anesthesia Care

by Gerald L. Zeitlin, M.D.

The Panel on Anesthesia Audit at the World Congress of Anaesthesiologists at the Hague provided the audience with interesting differences in attitude. In the United States, audit is called quality assurance, or in its latest transmogrification, continuous quality improvement.

During his introduction, Dr. Alaistair Spence, president of the (newly) Royal College of Anaesthetists in London, said that insistence by the government had led to the development of audit mechanisms in the United Kingdom.

The first two speakers were in striking contrast. Dr. Terry Vitez, Vice President for Medical Affairs at Premier Anesthesia, explained his method, well known in the USA, of judging clinical competence. The method accepts the idea that humans are inherently fallible, and that decisions about performance must be made by knowledgeable peers. He said these decisions must include measures of both the process and outcome of anesthesia. He has developed a zero to 10 scale of outcome scores which convert written descriptions of the outcome of an anesthesiologists care of the patient into a number. It is of interest that last year and in another context, the ASA House was concerned enough about the validity of placing a number on an anesthesiologist's competence that it referred the matter back to the Peer Review Committee for further study.

Dr. Spence followed by stating that although he remains optimistic about the usefulness of audit, he cautioned the audience that he is disillusioned about its possibilities. He warned us to limit what we audit only to key information; such things as drug usage, use of manpower and appropriate training, frequency of preoperative visits and problems of intubation. He said we should be wary of auditing complications because 'acceptable' rates of occurrence are unknown and vary with practice settings and the status of the patient. He had the same concerns about the study of critical incidents. He also emphasized that whatever system one used to audit patient care the validity of the findings must be tested and retested.

Dr. Fred Cheney, Director of the ASA Closed Claims Project, reviewed the information gleaned from malpractice case files and described the study of large numbers of adverse outcomes; the results can give perspective when performing audit. He stressed that the project results give no estimate of the overall incidence of adverse outcomes, that they are not balanced geographically in the USA and that there is selection bias in the claims that are reviewed. His most important statement about the applicability of the project's results to audit appeared when he described reasonable interrater reliability between the judgments of reviewers but marked bias against practitioners who had more severe outcomes even when the clinical scenarios were identical. This suggests a weakness in the Vitez method of enumerating a practitioner's competence and supports Dr. Spence's caution about validity.

Dr. Cheney described other findings from the project which have led to changes in practice. For example, the findings of the frequency and devastating consequences of difficulties with intubation have given an added incentive to the development of the difficult airway algorithm by the ASA.

Dr. John Lunn of the University of Wales stated that the Confidential Enquiry into Perioperative Deaths (CEPOD) is a form of audit. This enquiry is a rare example of cooperation between anaesthetists and surgeons! The enquiry extends to deaths occurring up to 30 days after surgery. Dr. Lunn said that this is not research because there is no prior hypothesis about perioperative death. It is ran independently of the government yet the authorities fund it. It is also independent of the Royal Colleges (the premier academic bodies in the U. K.) yet they act as watchdogs. In its study of perioperative death the enquiry seeks to avoid judgment of peers. But the enquiry does ask whether the care was appropriate or inappropriate. Dr. Lunn said therefore it is a form of quality assurance but he also warned that his case reviewers could be divided into hawks and doves.

The CEPOD, being national in scope, allows the collection of valid numerators and denominators. Each year there is a different focus; for example in 1989, the enquiry looked at perioperative death in children and this year, death rates associated with specific operations.

Dr. Burton Epstein, Chairman of the ASA Committee on Standards of Care, discussed the pros and cons of setting such standards. He quoted Dr. John Eichhorn's statement that anesthesia is the specialty most amenable to setting standards for itself. He added that the pressures for establishing standards largely came from government, insurers, third party payers and the public. He described how the ASA has updated monitoring standards as technology, experience and opinion have changed. He explained that the standards for obstetric anesthesia care have been liberalized to guidelines to respond to acceptable variations in practice. He felt that it was unlikely that any more new standards would be developed for anesthesiologists but that practice parameters (how to do it?) would take over.

Dr. Dupuy, a physician and an ethicist, followed and told us that in the past there had been reluctance to introduce audit in Continental countries; yet recently there had been an upsurge in interest. It sounded cynical, but she said that ethics, which is concerned with the quality of care, and economics, are linked. She explained this on the basis that money spent on one patient cannot be spent on another and medical audit tends to increase the number of medical interventions. The first part of this statement is not likely true of the USA except perhaps in Oregon. She described the activities of the Dutch Governmental Committee on Choices in Health Care. This committee strongly recommends the use of treatment protocols, the use of audit and gives advice on the how to deal with the 'difficult patient who shops from doctor to doctor in the medical mail.

It was clear to this audience that there is little unanimity about what is an acceptable and valid technique of auditing our care of patients but there was little doubt that we must do it.

Dr. Zeitlin is a member of the Department of Anesthesia, Brigham and Women's Hospital, Harvard Medical School, Boston, MA and is also an Associate Editor of the APSF Newsletter.

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ICPAMM Session Focuses on Anesthesia Crisis Management

Editor's Note: Presented here is the second half of an article begun two issues ago reporting on the meeting of the International Committee on Preventable Anesthesia Mortality and Morbidity last June prior to the World Congress.

Simulation in Anesthesia

Dr. Gravenstein described the potential usefulness of using realistic simulators for instruction in the use of crisis prevention and appropriate response to those crises that will still inevitably occur. He reviews the history of simulation in other fields including warfare and aviation. A distinction is made between training devices, including components of systems and simulators, which recreate the entire environment with some degree of realism. In anesthesia, there are numerous computer based systems that 'simulate ' some aspect of anesthesia. While these have great usefulness for teaching various topics, they are not in the category of realistic simulators. Dr. Gravenstein described the system that has been developed in Gainesville. It includes a mannequin, from which invasive and non-invasive blood pressures, breath sounds, heart sounds and carbon dioxide and anesthetic gas concentrations can be recreated. The system is a hybrid in that some variables are recreations of the real thing, e.g. ECG and oxygen saturation. The mannequin includes detail to the level of actual simulated muscle twitching for simulation of neuromuscular blockade monitoring. The entire system is operated by a computer from which various scenarios are enacted, altering the 'condition' of the patient and anesthetic situation to elicit responses from the trainee.

Simulators have applications for new residents, allowing to practice routine events and simple critical events. For the experienced clinician, the simulator allows experience in critical events such as anaphylaxis and malignant hyperthermia that would rarely, if ever, be encountered in practice. It is also possible to simulate multiple events and the kinds of distractions that occur in a real operating room situation. Dr. Gravenstein noted the work conducted by Dr. David Gaba at Stanford in recreating and studying the responses to such events. Simulators will also be very useful for training ancillary help, e.g., respiratory therapists and, perhaps, most useful for training anesthetists or assistants in rudimentary skills if extensive educational programs are not available. thus, someone could be trained relatively quickly to handle simple procedures and even manage simple crisis via the simulation environment.

Noting that simulator training is required in aviation and in other disciplines, Dr. Gravenstein feels strongly that this educational and training modality should be introduced into anesthesia. His experience is that it is relatively easy to train faculty as trainers. He estimates that the cost of a simulator in production would be on the order of $150,000 and that this expense would, of necessity, be supported by its use in training clinicians outside the sponsoring department. For comparison, aviation simulators, which cost on the order of 12 million dollars, are operated 22 hours per day. In response to question about the evaluation of the effectiveness of simulation, Dr. Gravenstein described a study conducted in Gainesville. Thirty-two residents were divided into two groups. Each group had the same curriculum with the exception of simulation training being available to one group. The simulator group was found to learn more quickly than the control group, which caught up after several weeks. Although the simulator probably has a role in retraining of anesthetists who may have been out of practice for a while and in testing or credentialing, neither of these possibilities has been examined yet.

An Algorithm for Crisis Management

The AIMS group has developed a strategy for crisis management based on an analysis of the first 1,000 reports they received (see earlier AIMS summary). The objective is to have a strategy that can be recalled easily during a crisis to permit rapid diagnosis and correction of a problem." The algorithm is based on the acronym COVER/ABCD. For COVER, there are two steps associated with each letter. For each step, there is a subset of considerations: C-circulation (check pulse, bl;good pressure, etc.0; C-color (check color and oxygen saturation); 0oxygen flow; 0 oxygen concentration(via analyzer); V vaporizer; V-ventilation (manually by removing ventilator-check compliance, breathing system, etc.); E-endotracheal tube; E eliminate machine (use self-inflating bag); R redo monitoring equipment (check all instruments for proper function); R review cover. The COVER algorithm is followed by the commonly known AKD Airway, Breathing, Circulation, Drugs. The investigation established this algorithm and a set of rules for assessing how each could be assessed for effectiveness in diagnosis and correction of problems described the AIMS reports. Using and initial set of reports, a first set of rules was established. these were further modified after independent review by each assessor of another group of reports. Of the first 1,000 reported, 72% were evaluated for how the protocol may have worked versus the anesthetist who was actually involved in the event. Of the remaining reports, 16% occurred int PACU, for which the algorithm is not necessarily intended and 12% of reports were not applicable to the algorithm for other reasons, e.g., cross matched blood not available, incorrect premeditation, wrong patient. The protocol was assessed to have performed correctly in diagnosing 99.5% of events with circulation(15%) and ventilation by hand(29%) being the two steps most frequently useful. Nine percent of events fell into the drug category of the ABCD portion of the algorithm. Of the 0.5% of reports for which the algorithm would not have made a diagnosis, the problems included pleural effusion and pheochromocytoma. The algorithm would have been useful for 90% of problems. Of these, the ABCD was effective in 60%. For the 10% that the algorithm would not have been effective, administration of the wrong drug was involved. Since this is only detected after the fact, by definition, correction is not possible.

It has been assessed that if the algorithm had been applied, it would have been more effective than the operator in 23% of the cases reviewed. In 705 of those cases, the algorithm and anesthetist were equally effective. In only less than one percent did the operator do better than the algorithm. (5% of cases were failed intubations, which were not assessed.)

Dr. Runciman believes that anesthetists should be trained to invoke this very simple concept instinctively. By teaching its use during routine scanning, anesthetists would become familiar with it and be prepared to implement it during a crisis. Since they have not validated this approach in any controlled trial as yet, this hypothesis remains to be tested. This issue provoked discussion about the need for intra-observer and inter-observer reliability in studies such as this. Dr. Cheney noted the usefulness of anthropology and health services training of the project director of the ASA closed claims study.

Accident Investigation as a Tool for Studying Anesthetic Mishaps

This topic was presented via a play, 'An Anesthetic Catastrophe", performed in three acts by Dr. J.M. Davies (the Investigator, Dr. A.K. Bacon), (Dr. Friend), (Dr. William Runciman, the Professor) and narrated by Dr. J.B. Cooper. The play portrayed an anesthetic catastrophe occurring in a small community hospital, involving a senior anesthetist (the professor) visiting for the day. The hypothetical patient was described as being healthy, undergoing a routine procedure, but suffered a cardiac arrest from which she could not be resuscitated. Following the event, Dr. Friend intervened to lend support to the professor and to guide the process of accident follow-up. The operating room was closed to assure nothing was disturbed, appropriate hospital authorities and the patient's family physician and relatives were contacted, arrangements were made for another anesthetist to take over the professor's cases for the remainder of the day and the accident was investigated thoroughly. Concepts were reviewed for general principles to be used in "breaking the news' and assisting the family. Dr. Friend helped the professor to debrief what happened. Later, he debriefed others on the team to elicit potentially useful facts. The investigator worked with hospital engineering to inspect the piped gas supplies and anesthetic equipment and drugs. Drugs were sequestered for later analysis. It was explained that the process is not to assess blame, but rather to establish what factors may have contributed to the event. The term 'cause" implies "blame so it is not invoked in this discussion. The Investigator created a chronologic list of all the events in search of possible contributing factors. The different factors were categorized as being .active' or 'latent' failures, the latter being 'resident pathogens' built into the anesthesia care system. Finally, recommendations were formulated for preventing future occurrences. During the course of this process, communication was maintained with the patient's family and with the Professor to provide emotional support.

The discussion following the play brought out many issues surrounding the concept of accident investigation. It was generally agreed that such thorough investigations rarely are conducted. Trained accident investigators are not generally available and protocols for conducting such investigations and assuring the kind of appropriate follow-up demonstrated in this play are not widely known. Several references were mentioned, including the report by Dr. Bacon of 'Major Anesthetic Mishaps Handling the Aftermath'.(14) A set of "Guidelines for Action following an Adverse Anesthesia Event" has been created (contact Dr. Cooper for copies) and is expected to be published soon. (15) Also, the recent Safe Medical Devices Act in the United States has led to dissemination of a protocol for device investigations formulated by ECRI. (16)

Despite the infrequency with which events are thoroughly investigated, several examples were given during the course of the discussions. (17) It was suggested that, given how rarely accidents occur, such an investigative protocol be implemented even for potentially serious events. Dr Runciman feels that critical incident reporting via forms is generally effective for this since most events have fairly simple contributing factors. Dr. Pat McKay emphasized the need to counsel staff, particularly the professor, following this event. Dr. Bacon offered that contacting the spouse of the affected anesthetist could also be useful.

On the subject of event reporting, Dr. Runciman suggested that competition be elicited over reporting the 'best' incident. Dr. Cheney reported some success in their institution at active incident reporting, which he attributes to a system using a single nurse who collects information on all events.

Dr. Gravenstein suggested that event reporting can create problems. When failure to extubate following a procedure was one of the events documented, residents apparently interpreted such events to have a negative reflection on their performance. This probably was the reason for a decrease in non-extubation, but a concomitant increase in reintubations in the PACU. Dr. Pierce voiced his strong support for the distribution and implementation of accident investigation protocols as illustrated in the play.


13. APSF Newsletter (Australia). Suggested protocol for management of anesthetic emergencies. A core algorithm "COVER ABCD, 1990,9:1-2.

14. Bacon AK: Major anesthetic mishaps. Handling the aftermath. Current Anaesthesia and Critical Care 1990; 1:253-257.

15. Cooper, JB, Cullen DJ, Eichhom JH, Philip JH, Holzman RS: Administrative Guidelines for Response to an Adverse Anesthesia Event. J Clin Anesth (in press).

16. ECRI: Investigating device related incidents. In Medical Device Reporting Under the Safe Medical Devices Act. ECRI. p. 23-30,1991.

17. Cooper JB, DeCesare R, D'Ambra M: An engineering critical incident Direct current bum from a neuromuscular simulator. Anesthesiology 1990; 73:168-172.

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The APSF and the APSF Newsletter regret failing to list two committee members in the Winter issue annual listing of all those contributing to the APSF effort.

Dr. Ervin Moss of Verona, NJ, is a member of the Committee on Technology.

Mr. Dennis McMahon, who represents the American Society of Anesthesia Technologists and Technicians, is a member of the Committee on liaison.

Both these committee members are recognized for their valuable contributions to the APSF.

... And Apology

The Anesthesia Patient Safety Foundation Newsletter is the official publication of the nonprofit Anesthesia Patient Safety Foundation and is published quarterly at Overland Park, Kansas. Annual membership: Individual $25.00, Corporate $500.00. This and any additional contributions to the Foundation are tax deductible. @Copyright, Anesthesia Patient Safety Foundation, 1993

The opinions expressed in this newsletter are not necessarily those of the Anesthesia Patient Safety Foundation or its members or board of directors. Validity of opinions presented, drug dosages, accuracy and completeness of content are not guaranteed by the APSF.

APSF Executive Committee:

Ellison C. Pierce Jr., M.D., President; W. Dekle Rountree Jr., Vice-President; David M. Gaba, M.D., Secretary; Burton A. Dole, Jr., Treasurer; Casey D. Blitt, M.D.; Jeffrey B. Cooper, Ph.D.; Joachim S. Gravenstein, M.D.; E.S Siker, M.D.

Newsletter Editorial Board:

John H. Eichhom, M.D., Editor; David E. Lees, M.D. and Gerald L. Zeitlin, M.D., Associate Editors; Stanley J. Aukburg, M.D. Jan Ehrenwerth, M.D., Nancy Gondringer, C.R.N.A.; Jeffrey S. Vender, M. D., Ralph A. Epstein, M.D., Mr. Mark D. Wood.

Editorial Assistant. Nola Gibson

Address all general, membership, and subscription correspondence to:

Administrator Anesthesia Patient Safety Foundation

520 N. Northwest Highway

Park Ridge, IL 60068

Address Newsletter editorial comments, questions, letters, and suggestions to:

John H. Eichhom, M.D.

Editor, APSF Newsletter

Department of Anesthesiology

University of Mississippi Medical Center

2500 North State Street Jackson, MS 392164505

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