Volume 8, No. 2 Summer 1993

Table of Contents

Upper Airway Management Guide Provided for Laser Airway Surgery
Fiberoptic Intubation Tape to be Distributed
Teamwork Among All in Operating Room Seen To Be Key Human Factor in Event Response
Letters to the Editor
In My Opinion: A Debate Will You Do an Elective GA Case with No Capnograph Available?
Experience is the Best Teacher:

Upper Airway Management Guide Provided for Laser Airway Surgery

Editor's Note: This article is an abbreviated version of a guide prepared by ASTM Subcommittee F29.02.10. Reprints of the original document are available from APSF. Address correspondence to APSF in Park Ridge, IL.

by The ASTM Subcommittee F29.02.10: Annette G. Pashayan, M.D., Gerald Wolf, M.D. Allan Gottschalk, M.D., Tom Keon, M.D., Jay Crowley, B.S., M.E., Albert De Richmond, M.S., P.E., and Robert Virag, B.S., M.S.

Lasers provide a source of intense energy that can ignite flammable material, such as tracheal tubes, catheters, sponges, or latex gloves, in the operative field.

Risk of fire is particularly enhanced in oxygen (02) and nitrous oxide (N20) enriched atmospheres. At the present time, we have no means of abolishing the risk of an airway fire during laser use. But there are available methods of airway management that reduce the risk of fire during operations in which a laser is used. Each method has its own risks and benefits. This guide summarizes current methods and informs clinicians of each method's applications, advantages, and disadvantages. No significance should be associated with order in which these practices are presented herein. This guide serves to assist the anesthesiologist and airway surgeon in their joint decision regarding selection of the most appropriate method for the individual patient and the wavelength of the laser to be used. This guide does not prescribe any one method of airway management. Decisions regarding practice methods can only be made by clinicians who have knowledge of the practice options as well as the needs of the individual patient.

Non-intubation Technique

These methods of ventilation do not use a tracheal tube. All non-intubation techniques have the following advantages: (1) there is no flammable material in the airway so that the risk of fire is minimized; (2) the method provides excellent visibility of the surgical field; (3) the potential trauma to the airway that a tracheal tube might cause is avoided.

Spontaneous Breathing Techniques

With the patient breathing spontaneously, an oxygen-enriched gas with or without potent inhalation anesthetic is insulated through a side port of the operating laryngoscope, a metal hook, or a catheter.' The anesthetic may be supplemented with intravenous agents and/or regional anesthesia to the airway. Disadvantages: Adequacy of ventilation cannot be assessed with capnography or spirometry. Pulmonary aspiration of gastric contents, surgical debris, and/or laser plume as well as inadvertent laser bum to the trachea are a risk since no tracheal tube is present. Ventilation cannot be assisted or controlled. Depth of anesthesia may fluctuate, and the patient may move. Insufflation techniques make scavenging anesthetic gases difficult. The risk of fire is increased if a flammable catheter is used as the insulation device.

Apneic Techniques

The patient s lungs are ventilated with a mask, through a tracheal tube, or via a bronchoscope using an oxygen-enriched gas, with or without potent inhalation anesthetic. The anesthetic may be supplemented with intravenous agents, muscle relaxants, and/or regional anesthesia to the airway. During ventilation, the laser is not used. Ventilation is then temporarily discontinued, and the mask or tracheal tube is removed. During apnea, 02 may be insulated while laser resection is performed with no flammable materials in the airway. After a period of time, laser resection is discontinued and ventilation is resumed. Periods of ventilation alternate with periods of laser resection/apnea. Disadvantages: Hypoventilation is a risk which may go undetected since capnography and spirometry are not applicable during apnea. Pulmonary aspiration of gastric contents, surgical debris, and/or laser plume as well as inadvertent laser bum to the trachea are a risk since no tracheal tube is present.

Jet Ventilation Technique

A metal needle or similar device is mounted in the operating laryngoscope and attached to a jet injector. The surgeon directs a high-velocity jet of 02 into the airway lurnen either above or below the glottis. The lungs are thereby ventilated with 02 and entrained room air.' Anesthesia is provided by intravenous agents supplemented by muscle relaxants. Disadvantages: Hypoventilation can be a problem with this technique due to any of the following: obstructive airway lesions, decreased pulmonary compliance (e.g., bronchospasm, obesity, or chronic obstructive pulmonary disease), and/or inability of the surgeon to direct the jet correctly. Adequacy of ventilation cannot be assessed by spirometry or capnography. The inspired 02 concentration cannot be controlled or monitored. Pulmonary aspiration of gastric contents, surgical debris, and/or laser plume, as well as inadvertent laser bum to the trachea, are a risk since no tracheal tube is present. Misdirection of the jet may cause gastric distention or barotrauma including pneumothorax and pneumomediastinum. With this technique, it is difficult to administer inhalation anesthetics.

Intubation Techniques

With intubation techniques, ventilation can be monitored and controlled, and both inhalation and intravenous agents can be administered. However, an 'ideal tracheal tube,' which does not ignite and yet has all of the characteristics of conventional tracheal tubes specified in ASTM F1242 (standard specification for cuffed and uncuffed tracheal tubes), does not exist. Therefore, this guide will now describe current intubation practices and how they affect the risk of airway fire.

Conventional Tubes

Conventional tubes may consist of polyvinyl chloride (PVC), red rubber, or silicone rubber. Polyvinyl chloride tracheal tubes are highly combustible when used in an oxidizing atmosphere. In certain well-controlled conditions, PVC does not ignite when in contact with the laser,(3) and FVC tracheal tubes have been used without causing fires when all conditions are met.(4) However, these conditions may be difficult to maintain in a clinical setting. Manufacturers discourage the use of unprotected PVC tracheal tubes in airway operations in which a laser is used. Presently available studies indicate that red rubber and silicone rubber tubes combust more readily than PVC tubes in air.(5) However, red rubber is more resistant to puncture and ignition by C02 laser energy than is PVC.(6) PVC tubes, if ignited, soften and deform. Silicone tubes, if ignited, become a brittle ash that crumbles easily and can separate and lead to retention of segments within the airway or be aspirated. In contrast, red rubber tubes, if ignited, tend to maintain their structural integrity. Each of the conventional tube materials has its own advantages and disadvantages for use with lasers (see Table 1). Advantages: Conventional tracheal tubes do not reflect laser light and so avoid injury to non-targeted tissue. These tubes and attached components are provided in sterile, preassembled, ready-to-use form and are intended for single use. These tubes do not retain and transfer heat to adjacent tissues, and meet standard specifications for cuffed and uncuffed tracheal tubes as outlined in ASTM F1242. Polyvinyl chloride tubes are transparent and so

condensation of airway vapor and evidence of combustion can be seen within the lumens. Disadvantages: Tracheal tubes made of conventional materials readily ignite and maintain combustion in the presence of oxidizing atmospheres. In the event of such a fire, the tube integrity may be compromised, allowing components to be retained within the tracheobronchial tree. Conventional tubes can produce products of combustion which are toxic to human tissue.(7)

Conventional Tubes with Protection

Flammable materials such as PVC, red rubber, and silicone can be wrapped with metallic tape, metallic backed surgical sponges, or other materials to shield the flammable material from laser contact. Advantages: Metallic wrapping may prevent the laser beam from igniting the tube yet still allow use of a conventional tracheal tube. A metallic backed surgical sponge has been designed specifically for use in airway laser operations. Disadvantages: Metallic tapes may reflect the laser beam onto nontargeted tissues. The user must apply the tape smoothly and continuously so as to prevent rough edges, which may abrade mucosa, and to prevent gaps, which expose the tube to the laser beam. The tape may cause the tube to kink. The metal backed sponge preparation diffuses beam reflection but adds considerable thickness to the tube; the sponge must be kept wet to avoid thermal injury, tissue abrasion, and fire. If the tape or wrap is dislodged, it may occlude the airway. &-cause tubes cannot be wrapped at or below the cuff, this area remains exposed and vulnerable to laser energy. The adhesive backing or surface coating of some tapes can be ignited by laser beams. Not all metallic tapes can protect all types of tubes from all types of lasers at every power setting. (8,9,10) Metallic wrapping does not necessarily confer an advantage when the site of operation is distal to the tube and/or the laser beam is delivered through the lumen of the tube. Sterility is difficult to maintain when tubes are prepared in this manner. Presently available metallic tapes have not been specifically designed for medical use. Therefore laser protection of tracheal tubes, other than that specified in certain products, is not the responsibility of the manufacturer of the product.

Ready-to-use, Laser-resistant Tubes

These are commercially available products designed for use during operations on the upper airway in which a laser is used. Many of these products have flammable components that can ignite if manufacturers' warnings, precautions, and directions for use are not followed.

Aluminum and silicone rubber spiral with a silicone covering and a self-inflating foam sponge cuff (Fome-Cuf, Bivona, Inc., Gary IN)

This item is intended for use with carbon dioxide (CO2) laser. Advantages: A traumatic external surface with a nonflammable inner surface. The cuff tends to maintain a seal despite penetration by the laser. Disadvantages: Flammable external surface and cuff. It may be difficult and time consuming to deflate the cuff if the cuff or inflation tube is damaged.

Airtight stainless steel corrugated spiral with a PVC Murphy eye tip and double cuffs (Laser Flex. Mallinckrodt, St. Louis. MO)

An uncuffed version is available for pediatric use. This item is intended for use with C02 or potassium titanyl phosphate (KTP) lasers. Advantages: Metal components are noninflammable. The tube maintains its shape during intubation and is kink resistant. The proximal cuff serves as a shield for the distal tracheal cuff. Disadvantages: Although metal may reflect the laser onto non-targeted tissues and result in damage, the matte finish and convexity of this product reduce this potential. The cuffed model contains materials which are flammable and requires that the cuff be inflated with saline to decrease the risk of ignition. Metal tubes are thick walled. The double cuff takes more time to inflate and deflate than a single cuff. Metal may transfer heat to adjacent tissue and other materials.

Silicone rubber tube covered with an aluminum-filled silicone layer (Laser-Shield. Xomed. Inc.. Jacksonville. FL)

This item, intended for use with the C02 laser, is no longer manufactured but may still be present in hospital inventory. Advantages: General characteristics similar to unwrapped conventional tracheal tubes (se above). Disadvantages: Can be ignited by lasers in the presence of room air and is difficult to extinguish once ignited.

Silicone rubber tube wrapped with aluminum and wrapped over with teflon (no adhesive is used in this process) (Laser-Shield 11. Xomed. Inc., Jacksonville, FL)

This item has replaced the original Laser-Shield. Methylene blue is contained in the pilot balloon. This item is intended for use with CO2 and KTP lasers. Advantages: The wrapping may prevent the laser beam from igniting the tube yet still allow use of a pliable tracheal tube. The Teflon coating is smoother and less traumatic than most manually wrapped tubes. The methylene blue in the pilot balloon will mix with normal saline and provide a marker of cuff perforation. An additional advantage of this product over tubes wrapped by the practitioner is that it is preassembled and quality checked by the manufacturer. Disadvantages: If the tape is dislodged it can occlude the airway. Tubes cannot be wrapped on or below the cuff, so this area remains exposed and vulnerable to laser energy. These tubes confer no advantage when the site of operation is distal to the tube and/or the laser beam is delivered through the lumen of the tube. Combustion and pyrolysis of Teflon yields toxic fluorinated by-products.

Silicone rubber tube uniformly impregnated with ceramic particles (LaserShielding Tube, Phycon, Fuji Systems, Tokyo, JAPAN)

Intended for use with Nd:YAG and C02 lasers. Advantages: General characteristics similar to unwrapped conventional tracheal tubes (see above). The cuff is thicker on the machine side to provide somewhat better resistance to laser puncture than most cuffs. Disadvantages: Can be ignited or punctured by laser energy. (11)

Metal Tracheal Tubes (12)

A flexible, non-airtight, interlocked metal spiral tube with a standard 15-mm tracheal tube adapter attached, these tubes are no longer manufactured but since they are reusable, they may still be in use. A polyvinyl chloride (PVC) or latex cuff may be attached by the user. Advantages: Under these conditions, metal is nonflammable. Disadvantages: These metal tubes are technically difficult to place in the airway and have joints through which airway gas can leak. Applying a cuff to the tube adds flammable material to the system. Metal may reflect the laser energy to nontargeted tissues and result in damage. The corrugated outer surface of metal tubes may injure mucosa. Metal tubes are thick walled. Metal may transfer heat to adjacent tissues and other material.

Additional Protective Measures

The following additional measures should be taken to help reduce the risk of fire:

* Limitation of oxidizers. The FiO2 should be limited to the lowest concentration necessary to maintain acceptable arterial 02 saturation. The balance of the fresh gas flow should be nitrogen and/or helium (3) potent nonflammable inhalation agents may be added as clinically indicated. Nitrous oxide should not be used. (3,6)

* Limitation of power density. The laser output should be limited to the lowest clinically acceptable power density and pulse duration.

* Saline-filled cuffs. Filling tracheal tube cuffs with saline serves as a protection against fire should the laser beam strike the cuff. However, the addition of fluid to the cuff system may prolong the process of cuff deflation. Methylene blue or other biocompatible and highly visible dye may be added to the saline to help detect cuff perforation.

* Saline-soaked pledgets. In order to provide some protection for the cuff, saline-soaked pledgets should be applied to reduce the likelihood of laser hit. The pledgets must be layered sufficiently and placed carefully to reduce the possibility of penetration. Pledgets, if not kept wet, may ignite. Nonmetallic strings attached to the pledgets can be severed and ignited by the laser. Care must be taken to retrieve 0 pledgets at the end of the operation.

* Other. Nonreflective operating platforms and other tissue-protective devices should be used whenever possible.

Since the only way to totally avoid a laser fire is to avoid use of the laser, practitioners must be prepared for such an event. Management of airway fires will be the subject of a future newsletter.

Dr. Pashayan is Associate Professor of Anesthesiology and Neurosurgery, University of Florida College of Medicine. Dr. Wolf is Professor of Clinical Anesthesiology, State University of New York. Dr. Gottschalk is Assistant Professor of Anesthesiology, University of Pennsylvania. Dr. Keon is Associate Professor of Anesthesiology, Children's Hospital of Philadelphia. Mr. Crowley is Systems Engineer, U. S. Food and Drug Administration. Mr. De Richmond is Senior Project Engineer, Emergency Codes and Regulations Institute, and Mr. Virag of Director of Research and Development, Mallinckrodt.


1. Johan TG, Reichert TJ. An insulation device for anesthesia during subglottic carbon dioxide laser microsurgery in children. Anesth Analg 63:368-370,1984.

2. Ruder CD, Raphael NL, Abramson AL, Oliverio RM. Anesthesia for carbon dioxide laser microsurgery of the larynx. Otolaryngol Head Neck Surg 89:732-737,1981.

3. Pashayan AG, Gravenstein JS, Helium retards endotracheal fires from carbon dioxide lasers. Anesthesiology 62:274-277,1985.

4. Pashayan AG, Gravenstein IS, Cassisi NJ, McLaughlin G. The helium protocol for laryngotracheal operation with C02 laser: a retrospective review of 523 cases. Anesthesiology 68:801-804,1988.

5. Wolf GL, Simpson JI. Flammability of endotracheal tubes in oxygen and nitrous oxide enriched atmosphere. Anesthesiology 67-.236-239,1987.

6. Ossoff RH. Laser safety in otolaryngology head and neck surgery: anesthetic and educational considerations for laryngeal surgery. Laryngoscope (suppl 48) 99: I26,1989.

7. Ossoff RH, Duncavage JA, Eisenman T'S, Kartan MS. Comparison of tracheal damage from laser-ignited endotracheal tube fires. Ann Otol Rhinol Laryngol 92:333-336, 1983.

8. Sosis M. Evaluation of five metallic tapes for protection of endotracheal tubes during C02 laser surgery. Anesth Analg 68:392-393,1989.

9. Sosis K Dillon F. What is the safest fog tape for endotracheal tube protection during Nd:YAG laser surgery? A comparative study. Anesthesiology 72:553-555, 1990.

10. ECRI: Laser resistant endotracheal tubes and wraps. Health Dev 19:112-139,1990.

11. ECRI: Laser resistant tracheal tubes, Health Dev 21:4-13,1992.

12. Norton ML, de Vos P. New endotracheal tube for laser surgery of the larynx. Ann Otol Rhinol Laryngol 87:554-557,1978.

13. Oxygen index of flammability: minimum concentration to support candle like combustion of plastics. Oxygen index, ASTM test D2W (08.02).

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Fiberoptic Intubation Tape to be Distributed

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

The Difficult Airway, Part 3, 'Fiberoptic Intubation,' ASA Safety Videotape No. 19, will soon be available for distribution by Burroughs Wellcome (BW).

This tape gives an excellent pictorial of endoscopic anatomy and the essential tricks and techniques of preparing a patient for either oral or nasal fiberoptic intubation during anesthesia or while awake.

Burroughs Wellcome funded The Difficult Airway, Part 3, through an educational grant, as well as Parts I and 2, which BW previously distributed. Part 1, "The Algorithm,' videotape no. 15, detailed development of an 'algorithm' for management of the difficult airway. Part 2, "Management The Cricothyroid Membrane," videotape no. 16, detailed the techniques of transtracheal jet ventilation, retrograde intubation and cricothyroidotomy.

The ASA Patient Safety and Risk Management Committee's Task Force on The Difficult Airway oversaw the entire Difficult Airway series. Task

force members include the following: Robert A. Caplan, M.D., chairman; Jonathan L. Benumof, M.D., Michael J. Bishop, M.D., Casey D. Blitt, M.D., Frederick W. Cheney, M.D., David M. Gaba, NO., Ellison C. Pierce, Jr., M.D., Mark H. Zornow, M.D., Andranik Ovassapian, M.D., and writer/producer Terence M. Davidson, M.D., Professor of Surgery (Otolaryngology, Head and Neck), Associate Dean for Continuing Medical Education, University of California, San Diego.

Hosts, narrators, and participants in fiberoptic intubation procedures in the film were: Terence M. Davidson, M.D., Jonathan L. Benumof, M.D., James H. Harrell, M.D., and Andranik Ovassapian, M.D.

The entire Difficult Airway series is a production of the office of Learning Resources-Television, School of Medicine, University of California, San Diego. The tape was filmed in the studios at the University of California, San Diego. In addition to producer Davidson, Beth Meyer served as director/editor, Dan Burke was engineer, and Beth Meyer and Mark Kearns were on cameras. Special thanks went to Scott W. Granger, Pentax Precision Instument Corp.

All tapes in the ASA Patient Safety Videotape Series, many of which are still available, are distributed by BW representatives.

Dr. Pierce is President of the APSF and Executive Producer of the ASA Patient Safety Videotape Series.

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Teamwork Among All in Operating Room Seen To Be Key Human Factor in Event Response

by Steven K. Howard, M.D.

A study of airline disasters conducted between 1968 and 1976 revealed more than 60 accidents which involved problems in team coordination. Similar to aviation, 65-70% of all incidents and accidents in anesthesia are attributed in part to human error. Adverse outcomes occur in both domains despite satisfactory technical expertise on the part of the professionals involved. Up until now in anesthesia, training and selection have focused almost exclusively on individual skills since we know very little about the factors that determine effective team performance. Nevertheless, successful operating room team interaction can be crucial for safe patient outcome. The following case report describes a situation where interaction between a skilled team was suboptimal and could have resulted in disaster.

Case Report: A 40 year old male was undergoing an aortic valve replacement for aortic insufficiency. As the surgeon was incising the pericardium with the electrocautery device, the patients heart fibrillated. The abnormal rhythm was quickly diagnosed by the anesthesiologist who notified the surgeon who then called for the internal defibrillator paddles. The surgeon asked for the defibrillator to be set on 10 Joules and then gave a command for the nurse to discharge the paddles. The nurse did not understand the surgeon's command to "shoot," and did not discharge the paddles until the anesthesiologist instructed the nurse to "hit it," which is the command usually used in this particular operating room for the nurse to discharge the defibrillator. This resident surgeon had not been acclimatized to the 'language' of this particular operating room and the members of the team were not communicating optimally during this crisis. Once the nurse understood the command, the patient was successfully defribrillated and the case proceeded uneventfully. The patient suffered no apparent effects from the brief arrest in the postoperative period.

What Makes a Team

Psychologists define a team as 'a distinguishable set of two or more people who interact dynamically, interdependently and adaptively toward a common and valued goal, and have each been assigned specific roles or functions to perform.' Imbedded in this definition is that task completion requires: (1) a dynamic exchange of information and resources among team members; (2) coordination of task activities; (3) constant adjustments to task demands; (4) some organizational structuring of team members. What makes teams different from mere groups of individuals is the fact that all teams share some form of interdependency between members. This definition obviously describes the operating room environment.

The ability of individuals to work together as a team is vitally important in many complex systems and the operating room is clearly no exception. Teams have obvious advantages over individuals in that they have a greater collective amount of knowledge and skill for problem-solving. Most important to team success is the interdependent nature of team dynamics since team members are able to pool information, share resources, and check errors in accomplishing a task. Poor team performance is often characterized by groups of individuals who lack interdependence or collective behavior of the team members.

In studies of teams, psychologists have categorized critical performance events into seven dimensions termed 'critical team behaviors.' The headings of these behaviors are as follows: communication, cooperation, team spirit and morale, giving suggestions or criticism, acceptance of suggestions or criticism, coordination, and adaptability. Sports teams exhibit excellent examples of both effective and ineffective team interaction. Individuals who perform well together as a team often display good communication, adaptability, coordination, team spirit and cooperation. Ineffective teams may have superior talent, but often do not fare as well as the "good' teams because of the lack of these critical team behaviors.

From the patient safety perspective, the most critical time for optimal teamwork is during the planning of the anesthetic and during crisis situations. The preoperative period is a crucial time for optimization of patient status prior to surgical trespass. The surgeon and other consultant physicians should communicate their concerns to the anesthetist who should design an anesthetic plan that will optimize the patient's chance for a good outcome.

Teamwork during crises is extremely important as exhibited by the case report. Surgeons are often preoccupied with the technical tasks of the surgical procedure and if problems are not communicated between the members of the team, adverse outcomes for the patient are more likely to ensue. Communications between anesthetist and surgeon should remain open at all times. If one member of the team is having a problem, other team members should be alerted and help in any way possible. For example, if the surgeon inadvertently cuts the inferior vena cava, the anesthetist and the nursing staff should perform the duties to which they are accustomed. For the anesthetist, this will involve support of the circulation and maintenance of oxygenation and ventilation. The nursing staff, under the direction of the anesthesiologist, should obtain help from outside resources to assist the team while the surgeon repairs the bleeding vessel.

Team interaction is studied extensively in other complex worlds (aviation, military, and perhaps most extensively in the space program). The operating room environment lends itself to the study and teaching of effective team interaction and should be a focus of future research for those interested in patient safety. Teamwork is currently being studied using videotape analysis in emergency departments (evaluating trauma teams) and in the operating room. These studies should help determine and evaluate the principles of teamwork that should be incorporated into our daily practice.

Finally, each member of the operating room team has his or her own unique contribution to add to patient care. By studying and understanding team dynamics, patient safety will be improved and job satisfaction likely enhanced.

Dr. Howard is a Clinical Instructor of Anesthesia at the Stanford University Medical Center and Staff Anesthesiologist at the Palo Alto Veterans Affairs Medical Center.

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Letters to the Editor:

More on 02 Tent in Cataracts

To the Editor

In 1989 we studied the questions about rebreathing and oxygenation during cataract surgery raised by your correspondents Drs. Shuput, Pollard, Shaw, and Mr. Simpson. (1)

We found that using an oxygen insufflating hoop gave the surgeon easy access to the eye and kept the drapes off the patients face. Oxygen at a flow rate of IOL. per minute was insufflated into the "tent" so formed. We then measured the PCO2 of the gas mixture under the drapes in 31 randomly selected patients. C02 accumulated in all 31 cases (mean +/- SD, 6.1 +/- 3.1 mm Hg). We did not measure arterial PCO2 and therefore do not know the clinical significance of this accumulation.

The fresh gas flow was reduced in a stepwise manner during the operation. One patient developed a headache as the fresh gas flow was reduced, and another patient exhibited PVCs. In both cases the experiment was abandoned, and the patients improved. All the patients remained fully saturated throughout. Reducing the oxygen flow below 10 L. per minute led to modest increases in C02 in the tent. At 5L. per minute the mean PCO2 was 10.1 +/- 3.2 mm. Hg. The application of suction at 8 to 10 L. per minute to the atmosphere in the tent resulted in only slight decreases in the C02 accumulation, ranging from 8 to 22%.

In an associated laboratory experiment, we found that paper drapes were permeable to C02 and plastic drapes were impermeable.

Gerald L. Zeitlin, M.D. Brigham and Women's Hospital Boston, MA


1. Zeitlin, GL, Hobin K, Platt J, Woitkoski N. Accumulation of C02 during eye surgery. J. Clin. Anesth., 1989; 1: 262-267.

Reader Disputes Idea of Reconnecting Loose Epidural Due to Contamination Risk

To the Editor

I was interested to read the review article in the winter issue of the APSF Newsletter on epidural anesthesia and in particular the discussion on the management of the disconnected catheter. I was concerned by the reviewers' conclusion that it was probably safe to reconnect a disconnected epidural catheter on the proviso that at least eight inches of the catheter were cut off under sterile conditions and that the cut end was treated with betadine. This conclusion was reportedly based on the findings of a study by Langevin and Gravenstein. The abstract (1) of the quoted study, however, states that fluid movement in a contaminated epidural catheter may lead to extensive contamination of the catheter. This would seem to preclude any consideration of reconnecting such a catheter. Moreover, it has been shown that following a similar decontamination procedure, intentionally contaminated epidural catheters show a significant incidence of residual contamination. (2)

The most prudent course of action to prevent catheter related infections is to select an epidural catheter hub/connector with the least likelihood of disconnection, to take all precautions to prevent disconnection, (3) and to remove or replace any catheters that become disconnected.' Any recommendation to the contrary is 'probably' not in the best interest of patient safety.

Robin J. Gavelin, M.D., FRCPC Assistant Professor, Director, Acute Pain Service

University of Texas Medical Branch Galveston, TX


1. Langevin PB, Gravenstein N. Epidural catheter contamination: effect of catheter position and meniscus on extent of contamination. Anesthesiology 77(3A); A1041, 1992.

2. Royal MA, Sutherland RM. A study of potential contamination rates with epidural catheter hub disconnections. Regional Anesthesia 18(25) ; 42,1993.

3. Gavelin RJ, Patterson K. Epidural catheter disconnections. Can J Anaesth 40(5); 468,1993.

4. Litwick K, Lubenow T. Practical points in the management of continuous epidural infusions. journal of Post Anesthesia Nursing 4; 327-30,1989.

Dangers from Substance-Abusing Anesthesia Personnel: More Debate

Good Chance for Safety Cited Due to Recovery Potential of abusers

To the Editor

All too often health care providers fail to comprehend the impact disease may have on the commission of illegal acts. I take distinct exception to the view Locke(1) recently espoused, in which she felt "substance-abusers in the medical field ... should go to jail just like we insist (on) our common folk" for possession of illegal drugs. Neither do I subscribe to her belief that "one of the big factors affecting patient safety today is the problem of the substance abuser being allowed to ... administer anesthetics," since it is estimated that only about 1% of anesthesia personnel noticeably abuse drugs.(2)

Not to detract from the potential for great harm an impaired provider could inflict during critical procedures (such as an anesthetic), drug abuse is a bona-fide medical and social disease. (3) It is both a symptom of and a response to maladaption to complex stresses in our environment. Some patients (yes, patients) arise from the combination of highly stressful occupations, perceived low self-worth, and both ready access and exposure to mood altering drugs. Few people more frequently fit this mold as do we anesthesia care providers: we strive each day to care for the most acute of medical situations, to clamor for some acknowledgement of our expertise from our peers, and yet not be taken in by the almost magical charms of the potent substances we inject into our patients and their effect. Chemical dependency is indeed a unique "occupational hazard' for anesthesia personnel, as described by Ward in his recent eloquent editorial. (4)Not an excuse for the illegal ramifications of abusing drugs, we still need to treat the disease (drug abuse) in order to obtain the best outcome (long-term survival, productivity to society, reestablishment of family/social/professional activities, etc. ). Incarceration and other civil penalties must take a back seat role, whether the abuser is a physician, nurse or just "common folk": a distinction only must be made between the drug abuser and the non-abuser manufacturer/distributor.

Studies such as the California Physicians' Diversion Program have demonstrated that anesthesiologists (both attending and resident level) can have a good chance of recovery, contradicting pessimism about recovery in this specific field. (5) Although the specific return to the specialty anesthesiology may not be prudent in all those addicted to drugs. (particularly for residents early in their careers (6) ), redirection into other medical fields may be appropriate in some cases, allowing continued rehabilitation while maintaining productivity and self-worth. This goal, however, cart only be achieved if the following occurs: expeditious identification of the drug abuser, removal from stressful medical environment, compassionate but firm and direct treatment from all health care providers involved, and-ultimately-appropriate and guided reentry into the medical (or nursing) field.

Timothy B. Gilbert, M.D.

Assistant Professor of Anesthesiology and Critical Care Division of Cardiothoracic Anesthesiology

The University of Maryland Medical System Baltimore, MD


1. Locke MR. Reflections on patient safety. APSF Newsletter, Winter 1992-3:51.

2. Gravenstein JS, Kory WP, Marks RG. Drug abuse by anesthesia personnel. Anesth Analg 1983;62:467-72.

3. Spiegelman WG, Saunders L, Mazze N. Addiction and anesthesiology. Anesthesiology i984;60:33541.

4. Ward CF. Substance abuse: now, and for some time to come. Anesthesiology 1992;77.619-22.

5. Pelton C, Ikeda RM. The California Physicians Diversion Program's experience with recovering anesthesiologists. J Psychoactive Drugs 1991;23:427-31.

6. Menk EJ, Baumgarten RK, Kingsley CP, Culling RD, Middaugh R. Success of reentry into anesthesiology training programs by residents with a history of substance abuse. JAMA 1990;264:2741-2.

What to do with the Older Anesthesiologist?!

To the Editor

The recognition that anesthesiology is a stressful specialty and the concern that a practitioner's performance may be adversely affected by such mundane yet ubiquitous factors as sleep disturbance or deprivation (APSF Newsletter Vol. 7, No. 4, 37), combined with knowledge of the inevitable, although individually variable, neurophysiologic consequences of aging,' raises the risk management issue for individual practitioners and organizations of what (if anything) to do with the older anesthesiologist?

At what point does experience no longer compensate for subtly diminished capacity to successfully process multiple simultaneous signals? How can we determine it is time to disengage from the more complex tasks before someone (or worse, some catastrophic event) tells us? How do we factor age, skill, work load, night call and compensation? Are there typically successful phase-out strategies for our specialty? Or, is clinical anesthesiology a young person's game?

I offer two not particularly original suggestions: The first is that we organize a widespread survey of anesthesiologists regarding how they approach the issues of the disengagement of older colleagues from clinical practice and retirement. A sample questionnaire has been devised and can readily be shared or used for a starting point with the appropriate committee or group.

My second suggestion is that appropriate groups sponsor regional or even national CME/symposium courses which would include such topics as:

The Problem:

1. The physiology of aging, particularly neurophysiologic and neuropsychologic changes;

2. Recognizing the subtle signs of age-related stress for the individual;

3. Recognizing the subtle signs of age-related stress for the department/group. Are there objective indices?

Are there lessons from industry (aviation)?

The Resolution: Preparing for the inevitable

Career redirections within anesthesiology

Career re-directions outside anesthesiology

Examples of successful plans

Future Implications:

Re-certification examinations

New technology to facilitate performance evaluation and to enhance performance

I sincerely believe this is an important topic that deserves our attention. I hope that my interest and that of other like-minded practitioners can stimulate some genuine progress in this important area.

Kenneth W. Travis, M.D. Assistant Professor, Anesthesiology Medical Director, Same Day Program Dartmouth-Hitchcock Medical Center Lebanon, New Hampshire


1. Dorfman LJ, Bosley TM. Age-related changes in peripheral and central nerve conduction in man. Neurology 1979; 29; 3844.

More on Post-op Pulmonary Edema: IV Fluid Administration Offered as Edema Cause

To the Editor

The Letter To The Editor by Dr. Lowell Garner, Pulmonary Edema After Appendectomies, was indeed very upsetting, especially since the five patients involved were all so young. Dr. Garner's discussion of the possible causes was somewhat incomplete, and it is because of this that I wish to make the following comments.

All the possible causes which were discussed were rare complications, most of which none of us has ever experienced, in spite of many years in anesthesia. I began my own practice as an anesthesiologist in 1956, i.e. almost 40 years ago. The single most common cause of pulmonary edema after surgery and anesthesia, which the author failed to mention, is still fluid overload!, regardless of who administers the anesthetic.

One should certainly be able to assume that fluid overload during a relatively short operation, such as appendectomy, where blood loss is usually minimal would never occur. In my own personal experience as a practicing and supervising anesthesiologist, this disaster occurs far more frequently than it should, even in the hands of highly trained and certified anesthesiologists or nurse anesthetists.

I would like to cite just one example, where this error was almost fatal in someone I dearly love.

About a year ago, my beloved wife of over 45 years had some gynecological surgery, consisting of a vaginal hysterectomy, A and P repair and bladder suspension. At the time of the operation, my wife was 76 years of age. The operation was done by a highly qualified gynecologist, and the anesthesia, a spinal (subarachnoid) anesthetic, was administered by an 'excellent" board certified anesthesiologist. Blood loss was more than had been expected, and even though my wife had donated a unit of blood prior to surgery, this was not administered until long post-op. Instead, as seems to be the practice these days, liter after liter of Ringer's Lactate was poured into my wife's veins. The fact that she was 76 years old was apparently completely ignored by her anesthesiologist.

When I first saw my wife postoperatively, her face was as white as a sheet and severely edematous, as were her hands and arms and feet and ankles. She had moist rates in both lungs, and her heart was severely irregular, with APCS, PVCs and runs of bigeminy and trigeminy. According to her doctors, she had already been given several doses of Furosemide (Lasix) intravenously. In spite of her edema, in spite of the diuretics used, in spite of her advanced age, Ringer's Lactate was still flowing freely into her veins. I do wish that someone could explain the rationale or rationality of this to me! I finally called one of my internist friends myself to come and to check her. As soon as he arrived, he changed the intravenous infusion to 5% D/W, and knowing of my interest, administered two grams Magnesium Sulfate intravenously, slowly. Her heart rhythm immediately returned to normal. He continued a slow IV drip of 5% D/W over the next five hours, containing five more grams of Magnesium Sulfate and 40 mEq of KCI. It took almost five days for her pulmonary and peripheral edema to subside. By the grace of God, and in spite of her mismanagement, she is doing well.

I know that something like this most likely did not occur in the appendectomies under discussion. But, as unlikely as it sounds,., fluid overload certainly is a possibility in these cases, especially since during the last few years, anesthesiologists seem to be so prone to pour in massive amounts of fluid indiscriminately, during anesthesia and surgery.

Bernard Horn, M.D. Diplomate, American Board of Anesthesiology, FACA, FACN (Emeritus) Benicia, CA

"Negative Pressure" Edema

To the Editor

This is in response to the query by Garner regarding the etiology of pulmonary edema after six cases of appendectomy in young adult patients. They suggest that because of the time frame involved (gradual improvement over 48 hours), negative pressure pulmonary edema is unlikely. There is no mention of a history of coughing, bucking or laryngospasm just prior to or after extubation.

In more than one institution I have observed a few episodes of similar pulmonary edema, but not necessarily in appendectomy patients. However all patients have been young, strong, minimally premedicated, and capable of generating a large negative inspiratory pressure with what would seem a minimal coughing/breathholding episode after extubation. This has been followed by fulminant frothy pulmonary edema similar to that described in Garner's letter. My experience in teaching institutions is that this tends to happen more in July, when new residents learn how to evaluate awakening and readiness for extubation, but these incidents happen to experienced anesthesiologists as well.

This phenomenon is well-known (1,2) to occur in young adults a well as others. It would be interesting if some specific additional predisposing factor were present due to the process of appendicitis itself. Infections are considered a predisposing factor for the development of pulmonary edema. (3) Perhaps they alter capillary permeability. However, the possibility also exists that the common factor is youth, and that appendicitis just happened to be present as well.

Dorene A. OHara, M.D., M.S.E. Assistant Professor of Anesthesia

University of Medicine & Dentistry of New Jersey New Brunswick, NJ


1. Kamal RS, Agha S. Acute pulmonary oedema. A complication of upper airway obstruction. Anaesthesia 39-.464467,1984.

2. Oswalt CE, Gates GA, Holmstrom FMG. Pulmonary

edema as a complication of acute airway obstruction. JAMA 2M:1&33-1835,1977.

3. Murray TR, Marshall BE. Cause and management of perioperative pulmonary edema. IN Paul C. Barash, Ed. American Society of Anesthesiologists, Vol. 15, Chapter 12. pp 149-163,1987.

Mishaps Involving IV Infusion Pumps Concern Reader

To the Editor

Having been an enthusiastic user of one particular brand of infusion pumps for intravenous medications during sedation or general anesthesia since 1987, 1 am struck by the 'regularity with which I encounter dosing problems. Elegantly simple and reliable when correctly configured in 90-95% of cases, these pumps nevertheless seem to be associated with a host of mistakes in my practice. I have committed each of the following transgressions while working solo, or with residents or nurse anesthetists, and my colleagues assure me that I am not alone. (Mishaps marked 'DWE' seem to have an incidence that Decreases With Experience on the part of the individual setting up the pump.)

1. Errors that result in an underdose:

A. The syringe barrel is mounted too high, so its flange is not gripped and the syringe merely slides when drug delivery is attempted [DWE]

B. The syringe is in place, but the plunger is not engaged by its driver, so no drug is delivered [DWE].

C. The microbore tubing has not been purged [DWE].

D. The microbore tubing is not connected to the

patients IV.

E. The microbore tubing disconnects from the patients IV (prevented by using locking connectors to the IV).

F. A leak between the syringe and the microbore tubing allows all drug to spill.

G. A reloading stopcock between the syringe and the microbore tubing is incorrectly set, allowing all drug to spill [DWE].

H. A 20 ml syringe is used in place of a 60 ml syringe [DWE].

I. Too low a patient weight is selected [DWE].

2. Errors that result in an overdose:

A. A 60 n-d syringe is used in place of a 20 ml syringe.

B. Too high a patient weight is selected [DWE].

C. A yellow propofol faceplate is used over the pump control knobs in place of a yellow midazolam face plate [DWE].

3. Errors that may result in an under or overdose:

A. An incorrect bolus dose is selected, 180 degrees on the dial away from the intended dose [DWE].

There is no question that following the manufacturer's directions minimizes the incidence of problems, but in my experience, the very ease with which these pumps can be recruited for a case seems to invite human errors. I suggest:

1. Assuring that the pump face template matches the drug being used.

2. Assuring that the syringe size matches the face template.

3. Double checking settings of all the dials.

4. Checking all stopcocks and connections.

Errors continue regularly to occur with this particular brand of infusion pump despite my awareness of their pitfalls. I would be interested to know if other clinicians have had similar experiences with pumps from any manufacturer.

Ronald M. Meyer, M.D. Assistant professor of Clinical Anesthesia Northwestern University Medical school Columbus Hospital Chicago, IL

Air from IV Bags May Pose Danger;

Venous Embolism Comes from Many Causes

To the Editor

The safe administration of intravenous (M fluids requires that the infusion apparatus be used correctly. I recently have cared for several patients in which the plastic IV fluid containers had been placed under the patients' heads in the horizontal position rather than hanging in the vertical position above heart level. In each case, it was noticed that air had displaced the fluid within the drip chamber and had entered the outlet tubing. Fortunately, none of the air reached these patients' veins. I measured the volume of air remaining in one container with a needle and syringe. The volume of gas recovered was 59 ml.

I contacted a representative of the manufacturer who stated that air within the fluid container is a normal by-product of the manufacturing and filling processes. The potential clinical significance of this finding prompted me to evaluate the presence of air within other plastic IV fluid containers utilized in our hospital. On inspection it appeared that all the IV fluid containers in the surgical suite contained air. Therefore, the volume of air was measured in the IV containers (PLI46) of nine additional patients, selected at random. The mean volume of air was 60.2 ml with a range of 56 to 68 ml.

The accidental administration of IV air is an infrequent clinical occurrence, but tiny air bubbles can enter the IV tubing when drugs are injected or when fluid containers are attached. These events are usually without consequence, but complications with serious morbidity or even mortality can occur. (1) An IV dose of 60 ml air if administered slowly would probably not produce serious consequences in a normal-sized healthy adult. However, the presence of compromised cardio-respiratory function, a relatively rapid rate of air administration, and the concomitant use of nitrous oxide (2) could contribute to increased morbidity and mortality. Furthermore, the presence of a patent foramen ovale could lead to arterial (paradoxical) air embolism. (3)

To avoid the potential complication of venous air embolism during fluid administration, all containers should be mounted in a vertical position above the level of the right heart. Patient areas in the pre-, intra-, and post-surgical areas (including transport) should have appropriate container supports. Health care personnel who administer IV fluids or blood, utilizing external pressurized systems, should be aware that intra-container air may gain access to IV tubing with subsequent delivery to the patient. Furthermore, the addition of air to any fluid container for the purpose of internal pressurization is extremely dangerous and should be avoided. Hospitals should address these problems with written policies.

Edwin S. Munson, M.D. Cincinnati, OH


1. Yeakel AE. Lethal air embolism from plastic blood storage container. JAMA 204:267-69,1968.

2. Munson ES, Merrick HC. Effect of nitrous oxide on venous embolism. Anesthesiology 27:783-87,1972.

3. Gronert GA, Messick JM, Cucciara RF, et al. Paradoxical air embolism from a patent foramen ovale. Anesthesiology 50:54849,1979.

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In My Opinion: A Debate
Will You Do an Elective GA Case with No Capnograph Available?

"Yes, Scheduled Anesthesia Services May Be Continued In Circumstances Where Capnography Becomes Unavailable Because of Equipment Failure"

by Hugh C. Gilbert, M.D.

Capnography has become an important aspect of intraoperative monitoring. Its value in assessing the appropriate placement of an endotracheal tube during the induction of general anesthesia has been strongly encouraged by the House of Delegates of the American Society of Anesthesiologists, and many departments of anesthesiology require continuous capnography as part of their rules of conduct for intraoperative care. Insurance carriers have embraced capnography as one of the important factors on which reductions in the cost of medical liability insurance coverage can be based.

The issue before us is not the value of capnography as a monitor for ensuring the adequacy of ventilation in patients undergoing anesthesia care, but whether an entire list of scheduled procedures should be canceled because intrument failure precludes end-tidal C02 analysis.

Clinical judgment requires anesthesia consultants to have latitude in choosing the means and methods for ensuring safe and effective anesthesia care. Capnography may be considered essential when the anesthetist is confronted with patients in whom malignant hyperpyrexia may be anticipated or in surgical conditions where one might expect pulmonary embolism secondary to air, C02 or fat. Capnography may be desirable in patients with a history of reactive airway diseases or abnormalities of pulmonary gas exchange.

While the sensitivity of clinical signs for the correct placement of the endotracheal tube have been questioned, competent clinicians have a great many techniques which will ensure the proper placement of an endotracheal tube. Auscultation, inspection, and the 'feel of the bag' are just as important to the clinician as instruments that quantify exhaled gases. In the circumstance of capnography being unavailable because of equipment failure, our clinical skills will permit continuation of anesthesia care. If the department requires documentation of the placement of endotracheal tubes, I would recommend bringing a fiberoptic bronchoscope into the room in question and then documenting on the chart that the endotracheal tube was placed in the usual fashion and that the correct positioning in the trachea was confirmed by bronchoscopy. Remember also, we still can administer general anesthetics by mask or even consider another favorite choice, regional.

Clinical judgment is the most important component of intraoperative monitoring. The instrumentation for intraoperative monitoring should always be considered adjunctive to the clinical judgment of competent anesthesia care givers. Unfortunately, legal issues often depredate the importance of clinical judgment. If I were faced with this situation tomorrow, I would try to obtain a replacement instrument to maintain the community standard of intraoperative capnography. If this were impossible, I would continue working on a case by case basis. Patients who have conditions in which capnography would be valuable in the manner outlined above would require rescheduling into another operating room. The remainder of that room's list could be continued so long as the administrative heads of the department of anesthesia, the hospital administration, and the involved surgeon were apprised of the situation and concurred. I believe anesthesiologists should have the capability to adapt to varying situations. During times of war or national disasters, safe and compassionate anesthesia care can be administered without the benefits of clinically useful but fragile instrumentation.

Dr. Gilbert is Assistant Clinical Professor, Department of Anesthesiology, Northwestern University, Evanston (IL) Hospital.

"No, Elective Surgery Should Not Be Done if Capnometry is not Available at the Start of a Case"

by Michael L. Good, M.D.

I would postpone anesthesia for elective surgery if I did not have a means to measure respiratory carbon dioxide. I postpone anesthesia very infrequently, because it significantly disrupts the life of my patients, who plan on undergoing anesthesia and surgery as scheduled. Postponement of a surgical procedure also severely hampers the efficient use of ever-decreasing healthcare resources. Nonetheless, the safety of my patient takes greater precedent than these concerns.

Each anesthesia provider must determine whether or not to proceed with anesthesia if the capnograph is not operational, as they must decide with abnormal laboratory results, inadequate preoperative fasting, or respiratory infection. My decision to postpone is based primarily on two arguments: (1) many of the problems which lead to patient injury during anesthesia are readily detected with capnography and capnometry, and (2) by prospectively developing an institutional protocol for capnograph failure, the need to postpone anesthesia for this reason should rarely if ever occur.

Unexpected adverse outcomes in anesthesia are rare but tend to be caused by recurrent mechanisms: esophageal intubation (1); inadequate ventilation of the patient's lungs (1,2) whether because of breathing system disconnections (3), leaks, or obstructions in the breathing system (4) failure of the mechanical ventilator, or other mechanisms; or difficult tracheal intubation.(1) Many deem capnography the best monitoring instrument to assist the clinician in detecting and managing these clinical problems. (2,5) Many other less frequent anesthetic complications are readily detected with the capnograph, (6) including malignant hyperthermia, pulmonary embolism (thrombus, air, fat, amniotic fluid), acute decreases in cardiac output, incompetent unidirectional valves, and exhausted carbon dioxide absorbent.

My decision to postpone anesthesia should a capnograph not be available is also shaped by experiences. I distinctly remember one patient with an unexpectedly difficult airway. An endotracheal tube was placed without visualization of the vocal cords. Its position was difficult to determine from observation and auscultation of the chest and abdomen. The patient's black skin made clinical assessment of hypoxemia difficult. In that particular operating room at that time (in 1984), there was neither pulse oximeter nor capnograph. Positive pressure breaths were delivered by the breathing bag; the patient's lung compliance seemed very poor, but she was somewhat obese. Repeatedly, the electrocardiogram showed bigeminy, but this resolved each time the seemingly stiff lungs were 'hyperventilated,' which suggested tracheal intubation. Several anesthesiologists were called to examine the patient; half thought the tube was in the trachea, and half thought the tube was in the esophagus. This experience is consistent with other reports suggesting that observation and auscultation of the chest and abdomen is not always a reliable way to differentiate tracheal from esophageal intubation. (1,7) The patient's course did not improve, until she began to breathe spontaneously, at which time it became clear that her esophagus was intubated. Because of persistent ventricular dysrhythmias, even when she was fully awake, her surgery was postponed. I am convinced that a capnograph would have facilitated early identification of the esophageal intubation and would have led to a different (and improved!) anesthetic course for this patient.

I take the position of postponement in this debate because I believe that the situation of being without a capnograph can be avoided. As anesthesiologists and anesthetists, we arrive in the operating room with not only a primary anesthetic plan, but backup plans as well. If regional anesthesia fails, we use general anesthesia. If the patient's blood pressure doesn't tolerate volatile agents, we may switch to a narcotic-based anesthetic or use vasoactive drugs. In the same manner, by prospectively developing a plan addressing failure of the carbon dioxide monitor, its failure need not postpone an elective surgery.

First, periodic checking, calibration, and other routine maintenance procedures should be followed according to schedules recommended by the capnograph manufacturer. Service should be performed only by appropriately certified individuals. Routine maintenance will keep the instrument in good working order and should reduce unscheduled down time.

The exact nature of the plan will differ for each institution depending on what " of instrument is used for respiratory carbon dioxide measurement: single-station infrared, Raman, or photo acoustic spectrometers or multi-station mass spectrometer. At the University of Florida, two multi-station mass spectrometers are the primary carbon dioxide measurement systems. Each serves approximately 10 anesthetizing locations. On one system, we have installed optional infrared C02 analyzers ('Life Watch') that monitor airway C02 when the mass spectrometer is servicing other stations. Thus, should the mass spectrometer fail, the infrared analyzers continue to provide C02 analysis. If the infrared analyzer in a particular anesthetizing location fails, the mass spectrometer continues to provide C02 analysis. The other mass spectrometer, an older unit, cannot be configured with the individual station infrared C02 analyzers. The rooms it serves are equipped with single-station infrared C02 capnographs. Thus, with isolated failure of either the mass spectrometer or the single-station capnograph, C02 analysis continues with the other system.

Institutions using single-station capnographs at each anestheting location should consider having one or more extra capnographs available as backups. If I were purchasing a capnograph today, I would seek a vendor offering a rapid response to my calls for service, and one who would provide a loaner instrument if my capnograph could not be fixed immediately. Lastly, if I were unable to acquire one or more capnographs as backup units, I would keep a supply of chemical C02 indicators on hand. While not providing all of the diagnostic capabilities of capnographs, these devices do allow the clinician to identify the presence and persistence of C02 in the exhaled gas, which I consider

the most important application for C02 monitoring. For patients at risk of developing problems readily diagnosed with the capnograph (for example, those susceptible to malignant hyperthermia, or undergoing craniotomy in the sitting position), I would insist on a capnograph, because I would be interested in monitoring for acute changes in exhaled carbon dioxide that cannot be easily detected with the chemical C02 indicators.

Most anesthetics usually can be completed safely without a capnograph, leading some to question its routine application in anesthesia. (8,9) Prospectively, we do not know when the capnograph will be needed or when it will make a significant difference in the patient's course.

Consider this analogy: You are boarding a jet airliner and as you pass the open cockpit door, you overhear the captain say, "Well, the radar is definitely out and can't be fixed but the weather is reported dear all the way and I think we can navigate and make it OK!" Do you want to ride that airplane at that moment?

Dr. Good is from the University of Florida and has been actively involved with studies on the quality and application of capnography.


1. Caplan RA, Posner K, Ward RI, Cheney FW. Adverse respiratory events in anesthesia: a closed claim analysis. Anesthesiology 72:828-833,1990.

2. Eichhorn JH. Prevention of intraoperative anesthesia accidents and related severe injury through safety monitoring. Anesthesiology 70:572-577,1989.

3. Cooper 18, Newbower RS, Kitz RI. An analysis of major errors and equipment failures in anesthesia management: consideration for prevention and detection. Anesthesiology 60.34-42,1984.

4. Cote CJ, Szyfelbein SK, Goudsouzian NB, Welch JP. lntraoperative events diagnosed by expired carbon dioxide monitoring in children. Can Anaesth Soc j 33:315-320, 1986.

5. Tinker JH, Dull DL, Caplan RA, Ward RI, Cheney FW. Role of monitoring devices in prevention of anesthetic mishaps: a Closed Claims Analysis. Anesthesiology 71:541,1989.

6. Good ML. Capnography: uses, interpretations and pitfalls. In Barash PG, Deutsch S and Tinker J, Editors. ASA Refresher Courses in Anesthesiology, Vol. 18, Philadelphia, 1991, Lippincott.

7. Birmingham PK, Cheney FW, Ward RI. Esophageal intubation: a review of detection techniques. Anesth Analg 65:886,1986.

8. Keats AS. Anesthesia mortality in perspective. Anesth Analg. 71:113-119,1990.

9. Orkin FK Practice standards: The Midas touch or the emperor's new clothes? Anesthesiology 70:567-571,1989.

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Experience is the Best Teacher:

by David M. Gaba, M.D., and Steven K. Howard, M.D.

In a previous edition of the Anesthesia Patient Safety Foundation Newsletter we requested that you report interesting safety-related events. The goal of this column is to advance safety by collecting event reports from anesthesia providers, analyzing the reports, and informing the anesthesia community about these occurrences and the lessons to be learned from them. The reports we have received to date have each been instructive.

"What harm can there be in giving a little potassium?"

A staff anesthesiologist at a university medical center was concurrently supervising two cases, each with an anesthesia resident. One case involved a patient undergoing resection of a cerebral AVM which had been proceeding uneventfully for 12 hours. The resident told the attending that he wanted to administer some potassium (K+) because the last serum K+ was 2.1 mEq/1. The staff commented that the hypokalemia was due, in part, to the hyperventilation which was in routine use for this neurosurgical case. The resident acknowledged this effect but argued that the diuresis produced by the routine administration of mannitol had increased urinary K+ losses, and besides, '...what harm can there be in giving a little potassium?' The staff anesthesiologist left the decision up to the resident and went to the next room to check on his other case.

About an hour later the case was taken over by the on-call resident after a hand-over from the original resident who informed his colleague that he had given 40 mEq of potassium about an hour before. Shortly after the hand-over, the attending returned to check on the case. He found the resident reaching up under the drapes. The resident said that the arterial trace had dampened and that he was checking to see if there was a kink. The staff looked at the monitor, found that the ECG, arterial, pulmonary artery, and central venous pressure tracings were all flat, and that the end-tidal C02 had dropped markedly. The surgeons were informed that the patient's heart had arrested and CPR was initiated.

Because the staff anesthesiologist suspected that the arrest was secondary to iatrogenic hyperkalemia, he insisted that all bags of IV solution be taken down and replaced with freshly opened bags of saline. After approximately six minutes of CPR the cardiac rhythm became sinus tachycardia with good arterial perfusion. A serum K+ drawn after the resuscitation showed a K+ of 9.2 mEq/l! The surgeons completed the procedure expeditiously and the patient was taken to the ICU in barbiturate coma. The patient subsequently did well with no deficit linked to the intraoperative arrest.

Afterwards, the staff and the residents were able to reconstruct the chain of events. The first resident elected to administer 40 mEq of KCl diluted in 100 ml of saline using a buretrol "minidrip" infusion set (60 drops = I ml) piggybacked into an infusion port on a blood pump peripheral IV set (See Figure). The buretrol was hung at a higher level than the peripheral IV which was running at a 'keep open' rate for the entire case. After the 100 ml of potassium-containing solution had dripped in, the infusion set was removed before the on-call resident took over the case. When the on-call resident opened the IVs to give some volume, a bolus of K+ (residing in the blood pump IV set and the remaining lactated Ringer's solution) was inadvertently administered.

The report states that the hospital has since formulated rules that K+ will not be administered intravenously unless its flow rate is controlled by a mechanical infusion device (pump or drip controller).

Analysts' Comments

The main culprit in this case was the administration of a drug into a large volume IV component with a slow rate of IV flow. In addition, the buretrol was hung at a higher level than the main IV which resulted in a 'reservoir' of drug that was rapidly infused when the IV was opened. Note that the hospital's new policy, while sensible for other reasons, would not necessarily prevent a recurrence of this event, since the potassium containing solution could still be administered into the "reservoir" by a mechanical device. A better policy change might be to require all piggybacked drugs to be infused using ports which are as close to the patient as possible and with adequate flow of the carrier solution to ensure the drug reaches the patient in a timely fashion.

There are other interesting issues raised by this case. When the cardiac arrest unexpectedly occurred, the resident's initial reaction was to assume that the arterial wave form had dampened due to a mechanical artifact without verifying that the patient was OK. The persistent attribution of abnormalities to artifacts in the face of abundant evidence to the contrary is a type of error the psychologists call a 'fixation error". Whenever seeing an abnormality, the "burden of proof' is on the anesthetist to prove that the patient is OK before assuming it's an artifact. In this case, feeling a pulse, listening for heart sounds, or looking at the ECG, filling pressures, and capnogram would each have demonstrated that the 'damped" arterial tracing was a real and lethal finding.

It is not clear in this case whether a more thorough hand-over between the residents would have helped avoid this complication, although it is possible that the on-call resident might have realized that administering the KCl in the proximal portion of the IV set could result in a reservoir effect.

Regardless, complete transfer of information about a case is imperative for safe patient care whenever a change of personnel takes place.

A final word about potassium. Unlike many drugs, for which the inadvertent administration of a few n-d would be inconvenient, the administration of potassium can be immediately lethal. Extraordinary care should be used however it is administered.

Perhaps this case answers the question: "What harm can there be in giving a little potassium?'

Dr. Gaba, Associate Professor of Anesthesia at Stanford University Medical Center and a Staff Anesthesoiologist at the Palo Alto Veterans Affairs Medical Center, is Secretary of the APSF. Dr. Howard is a Clinical Instructor of Anesthesia at Stanford University Medical Center and a Staff Anesthesiologist at the Palo Alto Veterans Affairs Medical Center.

Figure 1. IV set as described in the case report. The level of the buretrol is higher than the peripheral IV solution allowing for retrograde flow and a reservoir of potassium containing solution in the IV set. Potassium level in the remaining LR was measured at 9 mEq/l.

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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.

Joseph W. Pepper, Ph.D., President of Ohmeda, is a member of the Committee on Technology.

Allen Ream, M.D., Stanford University, is now a member of the Committee on Education and Training.

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

Also, Robert Caplan, M.D. is now chairman of the Committee on Liason because former chairman Casey Blitt, M.D. has become APSF Treasurer.

Lastly, the Editor sincerely regrets omitting the by-line crediting Jeffrey B. Cooper, Ph.D. with authoring the article 'ICPAMM Session Focuses on Anesthesia Crisis Management' in the Spring APSF Newsletter. Dr. Cooper's frequent contributions to this publication are much appreciated.

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; 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. Eichhom, M.D. Editor, APSF Newsletter

Department of Anesthesiology

University of Mississippi Medical Center

2500 North State Street

Jackson, MS 39216-4505

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