“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.