Pulse Ox Last Line of Defense

In his July President’s Update,¹ 2005 ASA President Eugene P. Sinclair, M.D., wrote: “Consider the fact that pulse oximetry was adopted by ASA [in 1990] as a standard of care because logic indicated that its use would reduce the incidence of brain injury, cardiac arrest and death.” We were struck that perhaps many do not appreciate the mechanism by which beat-to-beat monitoring of pO₂ has reduced hypoxic complications — not because it directly monitors oxygenation, but because it indirectly monitors ventilation.

In fact the prevention of hypoxemia (separate from ventilatory insufficiency) via SpO₂ monitoring has been shown for the most part to confer no benefit in the operating room for routine cases, wherein hypoxemia is common, yet patients suffer no sequelae. In 20,802 surgical patients,² oximetry monitoring was associated with a 19-fold increase in the incidence of diagnosed hypoxemia, yet a reduction in the overall rate of postoperative complications was not observed. Other studies,^3-4 even in children, reached the same conclusion. A Cochrane review⁵ confirmed detection of hypoxemia and related events but found no evidence that pulse oximetry affects the outcome of anesthesia. This is likely because in routine surgical patients who have no major pulmonary disease, as long as the lungs are ventilated, adequate oxygenation will occur. In fact the original primary impetus for pulse oximetry was to prevent catastrophic unrecognized esophageal intubation (prolonged lack of pulmonary ventilation), not to monitor oxygenation, per se. In earlier eras, moderate hypoxemia was undoubtedly rampant, yet patients did not die by the thousands or have hypoxic damage, even from anesthesia performed using deliberate hypoxic gas mixtures.⁶

Certainly anesthesiologists respond universally to desaturation by first checking the patient’s ventilatory status. Does it matter, then, whether or not they understand the true function of the pulse oximeter and how they are using it?

The proof that it does lies in the failure of anesthesiologists and other clinicians to deliberately use pulse oximetry as a ventilatory monitor in nonintubated patients in clinical situations where ventilatory insufficiency (as opposed to hypoxemia) poses the primary threat to life. This failure is demonstrated by the indiscriminant use of supplemental oxygen in such settings — as advocated for example by Mychaskiw⁷— thereby eliminating the only current means of monitoring ventilatory sufficiency in a quantitatively accurate manner.

Pulse oximetry is our last line of defense in avoiding ventilation mishaps and resulting catastrophic outcomes. Failure to appreciate and act on its role as such compromises the clinician’s ability to do the number-one thing that anesthesiologists must do, which is make sure that the green gas is getting to the lungs through a patent airway.

Leo I. Stemp, M.D.
Springfield, Massachusetts

Michael A. Ramsay, M.D.
Dallas, Texas

References:
1. Sinclair EP. Awareness — A personal viewpoint. ASA President’s Update. July 12, 2005; 8(1).
2. Moller JT, Johannessen NW, Espersen K, et al. Randomized evaluation of pulse oximetry in 20,802 patients: II. Perioperative events and postoperative complications. Anesthesiology. 1993; 78:445-453.
3. Mlinaric J, Nincevic N, Kostov D, Gnjatovic D. Pulse oximetry and capnometry in the prevention of perioperative morbidity and mortality [Serbo-Croatian]. Lijec Vjesn. 1997; 119:113-116.
4. Cote CJ, Goldstein EA, Cote MA, Hoaglin DC, Ryan JF. A single-blind study of pulse oximetry in children. Anesthesiology. 1988; 68:184-188.
5. Pedersen T, Pedersen P, Moller AM. Pulse oximetry for perioperative monitoring. Cochrane Database Syst Rev. 2001; (2):CD002013.
6. Erickson JC. A focus on history. ASA Newsl. 2001; 65(9):25-26.
7. Mychaskiw G, Badr AE. Case series or uncontrolled clinical study? Anesthesiology. 2005; 102:106.

‘Hey, Anesthesia’ Moniker a Sure Sign of Our Importance

First of all, Dr. Bacon, I enjoy your ASA NEWSLETTER pieces, but I would like to offer you a contrarian position about the November 2005 “From the Crow’s Nest” just to hear your take on my opinion.

I think that we continue to give up ground that we neither need to give up nor should give up to our other professional colleagues. The fact that anesthesiologists in some settings are referred to generically rather than by name is simply an indication that we offer broad, rather than narrow, clinical coverage. Sure, a surgeon will never be referred to as “Hey, Surgery!,” but that is because any given surgeon has a current scope of practice that extends about two feet in front of his/her face. And that is as it should be. A surgeon needs to attend to the patient and to the surgery to the exclusion of almost all else. Other than the rare circumstance when one surgeon requests emergency aid from another surgeon during a case, they could not care less about what else is happening in the rest of the hospital unless it impinges on their schedule. We, on the other hand, do care. We are the glue that holds the whole place together. We are the fire department that puts out the blazes, wherever or whenever they occur. We are the antiterrorism teams who quietly prevent the problems in the first place and remain nameless and faceless in the process.

In our own domains (not on call), most O.R. nurses and surgeons do know us by name. Face-to-face familiarity is probably the greatest justification for having subspecialization and divisional boundaries. I think we are more often “Dr. Bacon” and less often “Anesthesia.” But even when we are not, it is not necessarily inimical to our mission or our value to our patients and our hospitals.
When it hits the fan in an O.R., the call goes out for “Anesthesia!” not for “Dr. _______” (surgeon). Generic? Sure. So is a call for the Marines.

James R. Munis, M.D., Ph.D.
Byron, Minnesota

Nonanesthesiologist Providers are NOT Safe!

John P. Abenstein, M.D., wrote an excellent article titled “Anesthesia is NOT Safe” in the December 2005 issue of ASA NEWSLETTER. Although I agree with most of what he is saying, I do not believe his facilitatory conclusions could be more incorrect.

I believe that Dr. Abenstein eloquently stated that extensive training, experience and understanding of pathophysiology and pharmacology is required to even become an anesthesiologist. Yet I cannot agree that we have erred in any fashion by proclaiming the advances in the safety of the practice of anesthesiology.

I cannot quote a research source, but I think everyone will agree that the advances in open heart surgery have tremendously decreased the incidence of mortality when performing CABGs over the last 30-35 years. However, this does not mean that a dermatologist should start performing open heart surgery on patients who were referred to him to have an evaluation of a “skin rash.”

Two other salient points emphasized in the article are extremely troublesome to me. The first is the belief that the anesthesiologist should only intervene in the “difficult” sedation cases. The expectation that an anesthesiologist should intervene in the difficult case is not only unfair but is a fiscal impracticality. Doing only the difficult cases will not only ensure that your malpractice premiums will rise but that you assuredly will not have the funds to pay the increase. Secondly, to embrace the concept that we, as anesthesiologists, having spent a four-year residency program often working 80-90 hours/week, can now give weekend seminars to “credential” physicians who are not anesthesia-trained to administer propofol sedation is nothing short of ludicrous. This is very similar to expecting plastic surgeons to give a weekend course to credential all the anesthesiologists to perform liposuction and botox injections or the vascular surgeons to have a Saturday seminar for all physicians to be credentialed to perform arterial angioplasties and perform high-vein ligations.

I do agree that a comprehensive review should be in place in locations where anesthetics are administered with prospective parameters triggering case review. I also support the assertion that monitoring parameters should be set by the anesthesiology department. The involvement of an anesthesiologist, except to intervene during an emergency, should stop at this point if anesthesia personnel are not participating in the case.

If we as anesthesiologists acquiesce to the request that we credential nonanesthesia personnel to perform propofol sedation, then we also need to band together and all participate in a class action lawsuit against all of our anesthesiology residency programs because they masterfully deceived us into believing it took four years of rigorous training to learn physiology, pharmacology and airway management techniques that can easily be mastered in a weekend seminar. (I know that I am being facetious, but I think it clarifies my point.)

In conclusion, ASA should not now condone credentialing of nonanesthesia personnel to administer propofol sedation, but it should instead protect its members by issuing an immediate national condemnation to its endorsement. (We, as anesthesiologists, see it as a patient care issue [as it should be seen], but it truly is a greed issue for insurance companies and freestanding GI centers.) The primary reason we should not facilitate credentialing is because if we participate in the credentialing process, then we will have shared liability when we are called for the consciously sedated patient who “miraculously” had a respiratory arrest after a credentialed nonanesthesia physician administered propofol to the patient following our sedation guidelines and now the patient will most likely suffer from an irreversible anoxic brain injury regardless of what heroic efforts we perform to save his/her life after we arrive.
 
Keith M. McLendon, M.D.
Marietta, Georgia

Response to Dr. McLendon From Dr. Abenstein

I would like to thank Dr. McLendon for his thoughtful letter concerning my recent ASA NEWSLETTER article “Anesthesia is NOT Safe.” I would like to clarify several points. First, I agree that we have not erred in proclaiming the tremendous improvement in perioperative safety secondary to advances in the medical specialty of anesthesiology. Unfortunately our message has not always been clearly understood by those outside of our specialty. Many physicians and nonphysicians have interpreted our pronouncements as “anesthetic drugs are safe and easy to use.” Nothing could be further from the truth.

Secondly, in no way am I advocating that anesthesiologists should only intervene in “difficult” sedation cases, although I think it is important that we recognize that we cannot provide all procedural sedation. It seems reasonable that sedation with a small dose of midazolam or morphine during a superficial procedure does not often require the services of an anesthesiologist. I do think we have a responsibility, as members of the medical profession, to delineate which patients and/or procedures generally require the services of an anesthesiologist. In addition we also have the responsibility to assist our colleagues and institutions in developing policies and procedures to identify and intervene in those patients undergoing procedures requiring sedation who now require the care of an anesthesiologist.

No matter how finely tuned a preprocedural screening process, some patients will respond to sedation in unpredictable ways, and some procedures will go down unexpected paths. When this occurs, care rendered by an anesthesiologist is absolutely required. Whether or not we were involved in the case from the beginning, if our services are required to rescue a patient, I believe that we have an ethical responsibility to intervene.

It is the responsibility of medical facilities, not the department of anesthesiology, to credential and privilege their medical staff. Anesthesiologists can assist their respective organizations in developing appropriate credentialing and privileging guidelines for procedural sedation, including which medications are and are not appropriately administered by nonanesthesiologists, but it is the facility and not the anesthesiologists that bears this burden. As was noted in my article, the ASA House of Delegates approved credentialing guidelines for moderate sedation by nonanesthesiologists. The House was very clear in rejecting deep sedation. These guidelines are recommended for use by medical organizations. It would, in my view, be inappropriate for anesthesiologists to take on the responsibility of “signing off” on the privileging of individual nonanesthesioligists to administer procedural sedation.

It is perfectly reasonable for anesthesiologists to participate in the continuing medical education (CME) of physicians and allied health personnel in the appropriate and inappropriate use of procedural sedation. This is no different from cardiologists providing CME to anesthesiologists in the use of transesophageal echocardiology. Our participation in such CME will improve the quality of patient care and increase the involvement of anesthesiologists in the care of patients receiving procedural sedation.

Finally, I have to disagree with the issue of propofol. Although this medication has its own unique pharmacodynamic problems, specifically its rather narrow therapeutic range and a lack of a reversal agent, the issue is the depth of sedation/anesthesia and not the drug(s) utilized. One can get into just as much trouble with diazepam and meperidine as one can with propofol. It is imperative that the medical specialty of anesthesiology continues to engage this issue in order to decrease the incidence of oversedation and its related complications during procedures and to develop policies and procedures to increase the involvement of anesthesiologists in the care of these patients.

John P. Abenstein, M.D.
Vice-Speaker of the House of Delegates
Oronoco, Minnesota