Volume 8, No. 3, Fall 1993
Table of Contents

Cook Named 1993 APSF Young Investigator
Patient Safety Featured at Oct. 9-13 ASA Meeting
Guidelines for Pain Management MD's Are Published
Letters to the Editor
French Extend Monitoring Guidelines to Include Post Anesthesia Recovery
Ideas on "Anesthesia Workstation" Evolve Over Decades
Understanding Your Machine: O2 Flush Valve Key to Safety
Learning and Technology To Be STA Annual Meeting Theme; APSF Co-Sponsors January Confab to Be Held at Disney World

Cook Named 1993 APSF Young Investigator

Richard I. Cook, M.D., a resident in his final year of training in the Department of Anesthesiology, Ohio State University Hospital, is the recipient of the 1993 APSF 'Young Investigator's Award.' Dr. Cook received the award for his proposal, 'Investigation of Technology and Human Performance Interaction during Anesthesia.'

Dr. Cook began his career as a computer systems designer which led to his work developing computer based monitoring systems for operating room use. A 1986 graduate of the University of Cincinnati School of Medicine, he joined the Cognitive Systems Engineering Laboratory of Ohio State University in 1989 where he participated in research on human performance in anesthesiology.

The grant will support research into the ways in which new technology effects the conduct of anesthesia by skilled practitioners. Its focus is aimed at the impact of technology such as highly integrated monitors and computer based infusion pumps on anesthesia practice. Combining intensive observation and videotaping of anesthesia cases with construction of the reasoning and knowledge structures that drive the observed events, the study will trace the influences of technology on decision making in the operating room. The study is also intended to connect the details of device design with practitioner conduct in order to provide new insights for the evaluation of new designs. And finally, the results may provide information concerning the ways in which anesthesia decision making is constrained by the requirements of 'real world' practice and the current state of knowledge in the field.

Richard L Cook, M.D.

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Patient Safety Featured at Oct. 9-13 ASA Meeting

by John H. Eichhorn, M.D.

Patient safety once again will he prominently featured in the program presented at the Annual Meeting of the American Society of Anesthesiologists (ASA) in Washington, D.C., October 9-13.

Among the ASA Refresher Courses on Saturday, October 9, is a presentation by Dr. J. Ehrenwerth on electrical safety in the operating room. Sunday's presentations include a lead-off presentation by Dr. R. Caplan, one of the lead investigators of the ASA Closed Claims Study, entitled "Adverse outcomes in anesthetic practice: what are the data? Can outcomes be improved?' Later that day is a lecture by Dr. P. Kapur on the recognition and management of complications of ambulatory anesthesia.

In the Clinical Update Program at midday on Tuesday, October 12, Dr. R. Stoelting will give a presentation discussing changing perspectives on NPO status and aspiration pneumonitis. Immediately following will be Dr. D. Cook lecturing on the safe induction and emergence of the pediatric patient. At the same hour, Dr. J. Eichhom will present a safety-oriented discussion of risk management in anesthesia practice. The following day, Dr. J. Benumof will lecture on the management of the difficult airway with emphasis on the ASA algorithm developed by an ASA task force he headed.

Also on Tuesday morning, October 12, will be a three-hour panel discussion entitled 'Obstetrical anesthesia: how safe is it?'

Within the ASA meeting section on patient safety, epidemiology, education and history, there will be six scientific sessions containing 83 papers. On Monday, October 11, in the morning, there will be a poster-discussion session focused primarily on measurement of clinical performance, application of computers and use of simulators. Monday afternoon, a poster session on various clinical practice issues is scheduled. Tuesday, October 12, there will be an oral presentation session in the morning dealing with the history of anesthesia practice and related issues. That afternoon, another oral presentation session will contain papers addressing resident education and clinical teaching issues. Wednesday morning, October 13, there will be an oral presentation session focused primarily on airway management and related safety points. Finally, Wednesday afternoon, there will be a major poster session (one of the strongest of the meeting) with the theme of patient safety risks and outcomes.

Among the many safety-related topics that will be covered in the presentations will be several on the use of anesthesia simulators. Whether experience on these devices leads to improved clinical performance will be examined as well as aspects of their utility as teaching modalities.

Human factors contributing to anesthesia accidents will also be considered. For example, a study was conducted regarding the role of fixation of an anesthetist s attention in preventing the recognition of a potentially dangerous anesthetic overdose. Videotape analysis of practice characteristics was used in another study.

Another study evaluates the use of stethoscopes as continuous monitors, as suggested by the ASA monitoring standards. Several new and, it is hoped, better ways to evaluate and deal with patients' airways will again be offered among the presentations, as will several discussions of the effectiveness and safety of laryngeal mask airways.

Capnogram recognition by attendees at last year's ASA meeting was studied and the results will be presented. The source of latex allergens as a potential source of reactions will be discussed.

Attitudes of anesthesiologists about OR 'production pressure' (the demand for the maximal amount of service in the minimal possible time, even if safety corners must be cut) were studied and the possibly surprising results will be presented. Also, the new idea of incorporating anesthesia risk factors into OR scheduling parameters will be revealed and discussed.

The hypothesis that continuous non-invasive blood pressure monitoring may help reduce risk will be presented and tested. Cases in which 'too much drug" was given were analyzed and the causes will be presented. In another area, further work into the cause of the now-recognized syndrome of sudden cardiac arrest during spinal anesthesia is the subject of a paper. Also, the relationship of end-tidal carbon dioxide to arterial in sedated awake patients with blocks for cataract procedures, a topic directly related to a flurry of letters in recent issues of the APSF Newsletter, will be discussed.

Current attitudes toward NPO orders is the subject of a scientific paper, as is also the incidence of mortality associated with pediatric liver transplantation and the outcome of pancreas transplants. Differing risks for different CVP catheterization sites is also the subject of a presentation.

A new cement for total hip arthroplasty was examined for safety and efficacy and the results will be revealed. Factors involving potential laryngoscope contamination in differing settings were studied as well as a survey of methods used to clean laryngoscopes both will be presented. Further, there will be a follow-up presentation regarding the potential mechanism of infection in propofol liquid.

In all, the recent tradition of significant emphasis on patient safety at the ASA meeting clearly will continue this year.

Dr. Eichhorn, APSF Newsletter editor, is chairman of anesthesiology at the University of Mississippi, Jackson, MS.

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Guidelines for Pain Management MD's Are Published

A document entitled 'Critical knowledge and technical competence required of physicians involved in interventional pain management' has been developed by a task force organized by the Dannemiller Memorial Educational Foundation, an organizer of anesthesiology continuing medical education (CME) programs since its inception in 1984.

These guidelines arose from a need perceived by the Dannemiller group and specifically its President, Alon P. Winnie, M.D. of Chicago, due to the absence of any widely accepted standards of care concerning interventional pain management and, expecially, implantable pain control devices.

The Dannemiller task force comprised Drs. Winnie, Marshall D. Bedder of Portland, OR, Roger Cicala of Memphis, Elliott J. Krames of San Francisco, Carl Noback of Las Vegas, Gabor Racz of Lubbock, TX, and Steven D. Waldman of Leawood, KS.

Contained in the guidelines document are sections on: scientific basis, patient selection, patient management, implant techniques, practice considerations, and minimum requirements for physicians (such as a prerequisite of at least 16 hours of directly related CME, four of which should involve supervised hands-on surgical experience implanting devices).

A copy of the document and further information can be obtained from the Dannemiller Foundation; 12500 Network Blvd., Suite 101; San Antonio, TX 78249-3302; (512) 641-8311.

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Letters to the Editor:

More on Pulmonary Edema

Editor's Note: In the Spring issue, there was a letter to the Editor describing an unusual series of cases of postoperative pulmonary edema following appendectomies. Two follow-up letters appeared in the Summer issue and two more are published here.

Negative Pressure Edema Seen as Likely Cause

To the Editor

Negative pressure pulmonary edema should not be discounted as a cause of the pulmonary edema seen in the patients described by Dr. Garner (APSF Newsletter, Spring 1993). Negative pressure pulmonary edema remains a diagnosis of exclusion as there are no confirmatory diagnostic tests.(1) However, the clinical scenario Dr. Garner describes is exactly the one I would consider highly suspicious of negative pressure pulmonary edema.

Patients who develop negative pressure pulmonary edema are often young healthy adult males.' The period of airway obstruction can be extremely short (less than 60 seconds) and may be unrecognized when the patient is transferred to the Recovery Room. The presentation is often dramatic with pink frothy sputum. Aspiration can never be ruled out as a contributory factor, and it is known that regurgitation is more likely in the presence of a partially obstructed airway.'

I recently had a similar case of bona fide negative pressure pulmonary edema in a 24-year-old, otherwise healthy male, following an appendectomy. He presented dramatically in the Recovery Room after developing complete but transient airway obstruction (less than two minutes) on transfer from the Operating Room to the Recovery Room. He required continuous positive airway pressure and supplemental oxygen in the Intensive Care Unit for 48 hours.

In summary, airway obstruction (partial or complete), negative pressure pulmonary edema and aspiration are common variables in the development of pulmonary edema in the population of patients described by Dr. Garner.'

Scott A. Lang, M.D., FRCPC Assistant Professor

Department I Anaesthesia University of Saskatchewan Royal University Hospital

Saskatchewan, Canada S7N OXO


1. Lang SA, Duncan PC, Shephard DAE, Ha HC. Pulmonary Edema Associated with Airway Obstruction. Canadian journal of Anaesthesia 1990; 37: 210-8.

2. Calkin M Risk Factors for Negative Pressure Pulmonary Edema. Anaesthesia Analgesia 1993; 76: S32.

3. Illing L Gastroesophageal Reflex During Anaesthesia. Canadian journal of Anaesthesia 1992; 39:466-70.

Noted Expert Benumof Also Suggests Possible Negative Pressure Cause; Urges Extubation Caution

To the Editor

As a clinician with a special interest in/commitment to respiratory physiology, and in response to Dr. Garner's letter (APSF Newsletter, Spring 1993), 1 am aware of several other cases of bilateral pulmonary edema occurring in young otherwise healthy patients shortly after endotracheal tube extubation. My guess as to the etiology of the observations of Dr. Garner's group as well as those of other anesthesiologists, is that it may take only one very vigorous descent of the diaphragm against an obstructed airway to produce the edema.

In a young healthy patient, pleural pressure may become minus 100-200 mm Hg (although the transmural pressure across pulmonary vessels will be much less, it will still be significantly increased). Consequently, I can envision the transudation of fluid following just one sustained, vigorous, but unsuccessful, breath. The suppurative process described in the patients of Dr. Garner's group may have increased the permeability of the alveolar capillary membrane and thereby increased the risk of negative pressure pulmonary edema.

Based on all of the cases that I have heard of, I do not think the occurrence of this complication is as rare as may have been thought in the past. My take-home message is that the patency of the airway following extubation must be closely guarded (jaw thrust, oropharyngeal airway, etc.) for every breath until the patient can spontaneously maintain the patency of the airway. I would like to emphasize that these thoughts are only a guess, and I share the wish of Dr. Garner to know the thoughts of others.

Jonathan L. Benumof, M.D. Professor of Anesthesia

University of California, San Diego Medical Center

"Production Pressure" Danger Avoided by CQI Effort

Editor's Note: 'Production pressure' is the drive in many operating suites to do as many surgical cases as possible as quickly as possible in a given time period, usually the standard operating day. Hospital administrators want maximum efficiency out of their very expensive physical plant and personnel. Further, surgeons strongly agitate for optimal anesthesia "service,' particularly an absolutely minimum OR turnover time. These surgeons often threaten the hospital administrator with taking their cases to a competing hospital if they are delayed between cases, which 'wastes' their valuable time. The administrator then comes back to the anesthesiologists urging them to hurry. The pressure to cut comers, such as by not taking the time to get thoroughly familiar with a patient immediately preoperatively or to check equipment and supplies, is incredibly strong. The potential threat to patient safety is obvious.

by Diane Gulczynski, R.N., M.S., C.N.O.R.

Programs have been developed to help minimize OR turnover time without compromising anesthesia patient safety. Detailed in this article is one such effort which involved the application of a quality of care initiative.

Quality patient care in the operating room requires consistent and sustained collaboration among several major hospital departments. The traditional focus on the patient as the most important .customer" has often unwittingly prevented operating room personnel from recognizing the need to listen to the staff s perceptions of how other hospital systems can better support the operating room in providing quality patient care. The effective utilization of quality improvement techniques can only take place under strong leadership which is fully committed to the concept, as well as possessed of the discipline and perseverance to see it through.

At the New England Deaconess Hospital in Boston, key concepts of Total Quality Management and Continuous Quality Improvement programs have been integrated into key service quality initiatives. Deaconess Vice President and Chief Operating Officer Al Washko described these initiatives as .a strategically integrated process," driven by customer needs, which seeks to create a system in which individuals and departments participate in, are held accountable for, and are recognized for, improvements in quality of the provision of services. This process "is part of an overall management strategy," Washko explained. "It's not a 'project.' If s the way we live."

Indeed, the success of quality initiatives depends upon establishing a permanent culture of quality. This requires the formulation and articulation of a shared vision for the institution, the definition of basic management and employee expectations, education, and the monitoring of interdepartmental interactions through the collection of data. Also crucial to the creation of a culture of quality is collaboration among departments. Deaconess's quality initiatives have defined a structure based on "service units" the groups in each department that provide a particular service to other units. Each service unit supplies certain services to other service units, which consume these services. For example, service unit A is an 'internal supplier' of certain services and products to service unit B, which acts as an 'internal customer.' In turn, service unit B likewise 'supplies' other services and/or products to service unit A and/or other service units.

Ideally, the various service units follow mutually agreed-to standards to assure a smooth flow of quality services and products, which ensures both cost effectiveness and patient satisfaction at the same time. In short, interrelated service units should function as a team. At Deaconess, senior management from several departments involved in perioperative care seek to foster team collaboration by example. A surgical working committee, comprised of the Chair and the Associate Chair of the Department of Surgery, the Chair of the Department of Anesthesia, and the Director of Nursing/ Ambulatory and Surgical Services, meets regularly to look at opportunities to improve the efficiency of OR scheduling, to reduce turnover time, and to continuously and critically reassess the roles and responsibilities of personnel and departments involved in perioperative care.

OR Turnover Seen as Key

OR turnover has been a particular concern to the Surgical Working Committee. The reason is simple: any time spent cleaning up after the previous case and preparing for the next one is time that cannot be scheduled for surgery. Deaconess Hospital's identification of causes of excessive turnover time, and attempts to reduce the duration of this non-productive time, relied on the internal customer and supplier model: The goal of the perioperative nurse is to provide optimum patient care in a highly efficient, cost-effective manner. The perioperative nurse is dependent upon services provided by other departments in order to accomplish this goal. In preparing for the patient s admission to the OR, the perioperative nurse becomes the customer, awaiting the arrival of supplies contained in the case cart which was prepared in Central Processing. Additional items may be requested from other departments such as Medical Equipment and the pharmacy. Services provided intraoperatively by other departments may require preparation time before the patient's arrival. For example, a radiation therapy physician may come to the OR, activate the Intra-Operative Radiation Unit, and place it in stand-by mode prior to the patient's admission. All activities required for case preparation occur within the short period known as preoperative set-up time. This, combined with the time allotted for cleanup from the previous case, constitutes room turnover time. Problems with the delivery of supplies or services - including staff and equipment lateness, the malfunction of equipment, a missing or unsterile instrument - may arise, causing delay in completion of these activities, thus increasing room turnover time and, in turn, delaying the start of the next case.

Causes of Slow Turnovers

Over the past three years, the major causes of excessive turnover time and case delays at New England Deaconess Hospital have been identified. Programs were implemented to rectify these problems:

1. Inconsistent location and par levels of supplies used intraoperatively.

2. Lack of duplication of specific equipment required for the following procedure that was booked.

3. Ill-defined expectations of OR attendants, OR technicians, and anesthesia technicians relating to case preparation and room decontamination.

4. Late arrival of specific and late patient preparation by specific anesthesiologists for booked procedure.

5. Delays/case cancellation due to presurgical evaluation and detection of medical problems on the day of surgery.

6. Lack of a defined program of encouragement regarding enhanced work tempo during the nonproductive time between cases.

7. Consent forms not signed by patient and surgeon prior to procedure.

Continuous quality improvement techniques were applied to these problems to effect change in the OR staffs interactions with other service units.

Suggestions and consultation from operating room attendants, nurses and technicians were all used to make turnover quicker and more efficient. For example, Deaconess messengers were enlisted to transport more patients to and from the OR. This allowed the OR staff to concentrate on replenishing supplies of sutures, linen and other materials. The nursing staff also found other ways to make their use of OR time more efficient and reduce turnover time, including the conversion of a full-time OR technician position to a Biomedical Engineering position to assist the RN circulator with all laser and laparoscopic procedures. This individual is also available to assist the anesthesiologist, the CRNA, and the anesthesia technician in problem identification and resolution, thus saving wasted, nonproductive time. By keeping the experts at the bedside, the hospital can provide a higher level of care delivery to the patients. This is just one example of work restructuring that has benefitted the entire surgical team and has assisted in readdressing performance thresholds. Another example is a formal program of inventory management instituted in a joint venture between Materials Management and the OR. A product manager position evolved and eventually increased the department's responsibilities by taking on CPD as a prep and sterile department for the OR (instead of a distribution center for all patient care units).

In order to institutionalize quality improvement monitoring into perioperative care, the Deaconess Nursing staff, in collaboration with physicians and other specialty nursing groups, identified four important aspects of care for the intraoperative period and incorporated them into the operative record. The goal is to not only meet standards, but to constantly reevaluate those standards to ensure that the staff is providing the highest quality patient care in the most efficient manner possible. The four important aspects of care (IAOC), along with their respective expected outcomes (EO), are as follows:

1. IAOC: Management of anxiety related to perioperative events.

EO: The patient will demonstrate ability to cope with anxiety.

2. IAOC: Maintenance of skin integrity related to perioperative events.

EO: Skin condition will remain unchanged from preoperative state.

3. IAOC: Prevention of injury related to perioperative events.

EO: Patient will be free from injury upon discharge from operating room.

4. IAOC: Monitoring for fluid volume imbalance related to perioperative events.

EO: Patient's fluid balance will be monitored and supported.

In addition to these important aspects of care, a separate sheet is used for each procedure to record and track 'critical indicators' and occurrences, such as a break in aseptic technique, blood occurrences, complications, intraoperative delay, equipment problems, and incomplete preoperative patient preparation. Both the Important Aspects of Care and the Critical Indicators/Occurrence forms provide constant data to assist in the identification and rectification of chronic or recurring problems during perioperative care.

Another way in which continuous quality improvement was institutionalized was through the establishment of critical indicators for surgical delays, which allowed all forms of delay to be tracked. There are six specific categories of causes of delays: OR suite related, such as case cart problems and unrealistic estimates of procedure length; patient related, e.g. a patient who does not undergo pre-admission testing or a needed cardiac consult; consent-form related; support service related, e.g. delay in messenger services or blood bank services; anesthesia related, such as a difficult line placement or failure to complete pre-op assessment; and physician related, e.g. surgeon late, procedure improperly booked, or resident unavailable, Each delayed case is documented, monitored as part of a larger database, and the appropriate department is notified of the problem. The goal is not to look at personnel (whether it be surgeons, anesthesiologists, etc.) as chronic offenders, but to include those involved in looking at processes that might better improve systems, thus improving compliance.

Major Success

As a result of programs such as these, in 1991 turnover time decreased by more than 1,000 hours from the previous year, and again in 1992, the turnover time was decreased. By freeing up OR nonproductive time and turning it into productive time for more cases, this reduction in turnover time resulted in:

* Hundreds of thousands of dollars in potential revenues through increased time for case scheduling;

* Decrease in staff overtime required to finish each days cases;

* Increased patient satisfaction through more timely, dependable scheduling of surgery;

* Increased physician satisfaction with internal services; and

* Increased teamwork between a wide variety of hospital service units.

The success of Deaconess's Service Quality Initiatives illustrates the potential in terms of enhancing patient care, employee satisfaction, and the hospital's bottom line of the proper application of continuous quality improvement principles to perioperative patient care. Critical to the success of Ns endeavor are several components: the commitment and participation of employees at all levels within the organization, especially a unified interdepartmental management team; the institutionalization of quality improvement as an ongoing process through a variety of media, e.g. publicized monitoring reports in bulletin boards, and basic documentation such as the OR record; and imaginative work restructuring experiments which improve service and/or product provision, thereby enhancing the efficiency of the contributions of surgeons, anesthesiologists, nurses, and technicians to perioperative care. With its ameliorative effects on patient care, staff productivity and satisfaction, and the hospitals financial health, continuous quality improvement is not a desirable luxury; it is a critical component of any competitive strategy for all health care institutions seeking to flourish in the 21st century.

Ms. Gulczynski is Vice President for Surgical Services and Quality Initiatives at New England Deaconess Hospital, Boston, MA.

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French Extend Monitoring Guidelines to Include Post Anesthesia Recovery

by Professor J.C. Otteni

The 'Societe Francaise d'Anesthesie et de Reanimation' (SFAR) published in November 1990 "Recommendations for the monitoring and care of patients during post-anaesthetic recovery." They were produced by an ad hoc working party, amended by the general assembly held during 1990 French Congress of Anesthesiology and approved by the council of SFAR.

These new recommendations follow the "Recommendations for the monitoring of patients during anaesthesia' published in the Summer 1990 issue (pages 22-23) of the APSF Newsletter. They stress the value of pulse oximetry which should be available for all patients during transport and during their stay in the recovery room.

Professor J.C. Otteni is Chairman of SFAR's Working Party and of the Department of Anaesthetics and Surgical Intensive Care, University Hospital, Strusbourg-Hautepierre, France.

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Ideas on "Anesthesia Workstation" Evolve Over Decades

by Antonio Boba, M.D.

As introduction, one is reminded that in convergent evolution, the basic concept is: animals of different species, if placed in the same environment, would tend to develop similar traits, be it in the way they look or in the way they handle environmental factors.

The Spring 1992 issue of the Anesthesia Patient Safety Foundation Newsletter contained an article' which presented and discussed the concept of an .anesthesia workstation." The major focus of the article rested in stressing standardization of equipment among European, American, and other manufacturers as well as issues of safety. However, of equal if not greater importance was the description of what this 'workstation' is all about. One finds that it is a unit capable of delivering anesthetic gas mixtures and monitoring physiological variables (to include inspired/expired C02 among others). Also encountered is the concept that alarms should be prioritized and the recommendation that anesthetic mixtures should be sampled and monitored downstream from the vaporizers. Major emphasis is placed on the issue that 'MONITORS MUST COME ON AUTOMATICALLY WITH THE ANESTHESIA MACHINE' (emphasis in the original).

This is a tall order, and one might look at it as if it were a bold step forward. On the other hand, it is reasonable to note that about 20 years ago there appeared a monograph' in which this author introduced the concept of a single unit capable of delivering all gases and monitoring and recording in a continuous fashion the patients vital signs. Such a unit was called an 'anesthesia module" ( advance the concept that one should think more in terms of a unit that incorporates monitoring, recording and decision implementation subunits into a single compact and mobile tool. For such a unit ... we prefer the words 'ANESTHESIA MODULE').' The use of continuous monitoring of ventilatory functions was proposed and an example of one such module incorporating a capnometer coupled to a continuous recorder was also shown. The concept that alarms and signals to be displayed should be prioritized was discussed ('In this context, one should ... establish a certain order or priorities so that all messages may be organized in a certain order on the basis of their content,...'). Equally interesting, the concept that monitoring of all delivered gas mixtures should be carried out downstream from the vaporizer was also espoused.

As for the value of, and need for, high quality monitoring, it was stated as '...the acquisition of information is the cornerstone of anesthesia. Without it anesthesia is not possible, and its quality and quantity determine the quality of anesthesia itself.'

Today, one could be tempted to say that we are looking at a case of convergent evolution in the development of anesthesia equipment.

However, on second look, one observes that even though the environment remains the same (i.e., the operating room) the pressures leading to the development of the "anesthesia module' and the 'anesthesia workstation' were quite different.

In the current situation today, the major emphasis was placed on issues of standardization and safety with limited consideration being given to underlying systematic issues. Conversely, the case 20 years ago for the 'anesthesia module" was based on a systematic analysis of the administration of anesthesia viewed as a process (a series of sequential and interdependent decisions). The proposed module was advanced as a means of delivering to the anesthetist accurate information upon which to make a decision. A plea was made to the effect that in many instances, a glut of information clutters and hinders the decision-making process, hence again the need to prioritize messages. Finally, it was pointed out that the structure and the format of the message are critical and that in fact in many instances the content and format of the incoming message control the decision itself. Ultimately, the need for continuous recording was stressed.

Data Need Leads to Module

Historically then, this "module' was developed and tested because a systematic analysis of the anesthetic process pointed to the primacy of the decision-making sequence and because valid decisions can be made only on the basis of immediate access to reliable information.

If the hypothesis that this is a case of convergent evolution is correct, then the proposed current workstation is equivalent to the old module only if it came about under the pressure of analogous systematic analysis of its functions. A brief list of such criteria follows.

One should give serious consideration, and for obvious reasons, to issues that are part of the anesthetists behavior at his workstation without being necessarily part of the 'anesthetic process."

First, one would need access to extensive and detailed studies of time and motion during administration of an anesthetic. These would be of great value in determining where to put controls and message displays (in rows? in vertical stacks? in clusters?). Unfortunately, very little has been done beyond observation in this area',' and certainly hardly enough to lead to the design of an experimentally tested workstation.

Second, one should recognize that all monitoring can be reduced to the transmission of a signal from one point (the patient) to another point (the record). Within this context the signal to be transmitted must be clearly defined in terms of its frequency and amplitude in order to insure errorless transmission.

In regard to blood pressure, it has been shown that while the blood pressure is measured or sampled, the actual signal being transmitted is "blood pressure changes over time' and the collected data indicate that this latter signal has a much smaller amplitude than the blood pressure itself and that it is nonperiodic. This lack of periodicity precludes the selection of a sampling frequency which is wholly dependent on the frequency of the signal itself. Hence, the unreliability of the sphygmomanometer and the need for continuous and independent recording of the blood pressure is demonstrated.' Later studies have confirmed this.' Unfortunately, similar studies for the pulse rate and the end-expiratory pCO2, just to name two valuable pieces of information, simply do not exist.

A third issue in the construction of any such piece of equipment has to do with human performance, and this subject should be divided into two separate subsections. The first is the recognition that managing an anesthetic is for the most part a .surveillance Wk," often quite monotonous. While work has been done on the subject of improving performance during monotonous surveillance tasks (both experimentally and in the industry) none has appeared that specifically addresses anesthesia. Finally the issue of actual human performance in terms of body mechanics should be addressed. For instance, placing flowmeter controls seven feet above the floor obviously will not do (ditto for push buttons that are 3.0 mm in size and closely clustered or stacked). The basic information pertaining to this issue is readily available,' but so far one would have to guess that it has not been thoroughly evaluated and incorporated by the manufacturers of anesthesia equipment (my personal experience with industry representatives is that they are not aware of the existence of such information).

In summary, it would be my opinion that because of the perception that much "good" will be generated by the standardization and consequent supposed safety of anesthesia workstations, there will occur a prompt widespread adoption of such recommendations. Unfortunately, the adoption of standards that are not based on a sound and systematic analysis of the issues could result in hampering rather than enhancing any understanding and managing of the anesthesia process for a long time to come.

Dr. Boba is a member of the Department of Anesthesia, Northern Dutchess Hospital, Rhinebeck, NY, and the Department of Medicine (Intensive Care), Saint Francis Hospital, Poughkeepsie, NY. He has long been interested in the theoretical aspects of the anesthetic process and of medicine in general.


1. Weitzner S. European "workstation" rules will influence U.S. Anesthesia machines. Anesthesia Patient Safety Foundation Newsletter 1992,7.1-6.

2. Boba A. Essays on future trends in anesthesia. Springer Verlag, Berlin Heidelberg. New York, 1972.

3. Boba A. ibid., P. 22 (by permission).

4. Drui AB, Behm RJ, and Martin WE. Predesign investigation of the anesthesia operational environment. Anesthesia and Analgesia ... Current Researches 1973:52:584-591.

5. McDonald JS and Dzwonczyk R. An activity analysis of the anesthesiologist's Interoperative time period. Anesthesiology 1984; 61:A466.

6. Boba A. Blood pressure changes over time during anesthesia (general considerations and observational data about the amplitude and the frequency of the signal). Anesthesiology 1982@57A449.

7. Logas WC, McCrathy RJ, Narbone RF, and Ivankivich AD. Analysis of the accuracy of the anesthetic record. Anesthesiology 1987;66:SI07.

8. Damon A, Stoudt HW, and McFarland RA. The human body in equipment design. Cambridge: Harvard University Press, 1966.

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Understanding Your Machine: O2 Flush Valve Key to Safety

by Clayton Petty, M.D.

Many anesthesia providers use the oxygen flush valve daily especially in those cases where the face mask fit is not optimal during the induction. When an emergency occurs it is comforting to know where a supply of oxygen is readily located, how much can be delivered, and that a flow is available despite the anesthesia being lifted on or off.

When ether and chloroform were introduced as anesthetic agents, they were delivered with air as the carrier gas. Nitrous oxide was then introduced with air and nitrous oxide as the carrier gases. Oxygen enrichment in the carrier gas was a relatively late introduction into the practice of anesthesia. However, oxygen enrichment carrier gas is now considered a critical component of any general anesthetic and is even used to supplement regional anesthesia and monitored anesthesia care.

The oxygen flush valves on anesthesia machines manufactured in the United States today have many excellent safety features:

1. Color coded

2. Labeled "02' 3. Self-closing

4. Delivers 35-75 L/min

5. Protective rim

6. Mounted on the front of the machine for easy accessibility

7. Delivers oxygen directly into the common gas outlet without passing through a flowmeter or vaporizer

Oxygen is supplied directly to the oxygen flush valve. Figure I demonstrates the common pipeline connection of the oxygen supply from the hospital pipeline and the oxygen supplied from the oxygen compressed gas cylinder. The anesthesia machine oxygen pipeline is then divided with one branch controlled by the on/off switch of the anesthesia machine and the other branch going directly to the oxygen flush valve. As long as oxygen pressure is present in the common anesthesia machine pipeline, the oxygen flush valve can be activated with or without the main switch of the machine being on. Oxygen passes through the oxygen flush valve into the common gas outlet and directly into the patient s breathing circuit.

A typical oxygen flush valve assembly is shown in the schematic of Figure 2. The anesthesia machine pipeline pressure of 40-50 psig pushes a ball valve against a circular valve seat (Figure 2A) which stops flow of oxygen through the oxygen flush valve. When the anesthesia provider presses the flush button (Figure 2B), the pin lifts the ball valve off the valve seat and allows oxygen to flow into a common gas outlet at a rate of 35-75 L/min. When the anesthesia provider releases the flush button, the hall valve retaining spring forces the ball valve to seat and flow is stopped.

The oxygen flush button is something we certainly do not need to use on every case but its presence should give us a certain sense of security and perhaps even a little peace of mind.

Dr. Petty is Professor of Anesthesiology, Uniformed Services, University of Health Sciences, Bethesda, MD and currently Professor at the University of Utah at St. Mark's Hospital, Salt Lake City.

Figure 1. A pipeline diagram of an oxygen flush valve. Note the direct pipeline of oxygen to the flush valve. Released oxygen bypasses the flowmeters and vaporizers and enters directly into the fresh gas common outlet. (Redrawn from Technical Services Manual. North American Drager, Telford, PA 1985.)
Figure 2. Oxygen flush value for the anesthesia machine. (A) A spring holds the ball valve against the valve seat when the oxygen flush valve is in the closed position. (B) Pushing the oxygen flush button inward forces the ball valve off the valve seat and the oxygen flows into the common gas outlet of the anesthesia machine. (Reproduced with permission from Bowie E, Huffman LM: The Anesthesia Machine Essentials for Understanding. Ohmeda. The BOC Group, Inc. 1985.)

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Learning and Technology To Be STA Annual Meeting Theme;
APSF Co-Sponsors January Confab to Be Held at Disney World

Technology and learning will be the theme of the annual meeting of the Society for Technology in Anesthesia (STA) set for January 27-29, 1994, in Orlando, Florida, at the Walt Disney World Dolphin. The meeting is being co-sponsored by the APSF and the Society for Education in Anesthesia (SEA) and will be devoted to exploring the importance of technology in anesthesia education and safety.

Panel discussions and working groups will develop the theme "Learning About Technology Technology About Learning.' The panel discussions will include:

* SEA Panel: Co-chairs Phil Malan, M.D., from the University of Arizona and Michael Good, M.D., from the University of Florida will moderate a discussion of the concept that technology can enhance the educational process. This session will also introduce the audience to the various simulators and training devices that will be available throughout the meeting.

* STA Panel: Robert Chilcoat, Ph.D., BOC, and Wesley Frazier, M.D., Emory University, will discuss what the clinician needs to know about technology and what the technologist needs to know about medicine.

* APSF Panel: Frances Rhoton, Ph.D., Case Western Reserve University, and E.S. Siker, M.D., Executive Director, APSF, will discuss how to introduce technology and safety questions more firmly into the curriculum of anesthesia training programs and continued education in anesthesia.

Several working groups are also planned to bring the talents of the meeting attendees to bear on the problem of what is really important to understand about technology to function effectively in the clinical setting. A separate working group will be constituted for each of several monitoring modalities including ECG, blood pressure measurement, pulse oximetry and others. Each group will be asked to describe a clinical scenario that illustrates why the user needs to be familiar with one or more technologic features of the device to guarantee safety or proper usage. These working groups are being organized by Gordon Gibby, M.D., University of Florida, and Daniel Raemer, Ph.D., Brigham and Women's Hospital.

In addition to these formal sessions, a variety of simulators and training devices will be available for examination throughout the meeting days. Sem Lampotang, Ph.D., University of Florida, and Charles Brindis, M.D., MS., are organizing these sessions. Scientific sessions are also planned where abstracts will be presented in a poster-discussion format.

In addition to Disney World and Epcot, the Orlando area has many other pleasant diversions available to meeting participants and their families. The STA meeting is being held in one of Disney's finest hotels on the grounds of the resort, and social events are also being planned.

For more information on the meeting, contact the STA National Office at (804) 378-4959.

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

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. Ian 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: Ms. Nola Gibson

Address all general, membership, and subscription correspondence to:


Anesthesia Patient Safety Foundation 520 N. Northwest Highway Park Ridge, IL 60068

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

John H. Eichhorn, M.D. Editor, APSF Newsletter

Department of Anesthesiology

University of Mississippi Medical Center

2500 North State Street

Jackson, MS 392164505

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