Evaluation of Anesthesia Case: Failure to Maintain a Patent Airway
The practice of anesthesiology is broad in scope extending from the control of pain and consciousness in the operating room or elsewhere to the control of pain generally in the hospital or even in the outpatient setting. In the operating room, the anesthesiologist, in addition to having an extensive monitoring role, has independent responsibility for evaluating and supporting cardiopulmonary function. Because of their monitoring functions, anesthesiologists, as a rule, document their activities contemporaneously and more thoroughly than any healthcare provider other than perhaps the critical care nurse. In addition, because errors in the administration of anesthesia can result in catastrophic injuries (which were often preventable) the specialty has evolved more thorough and rigid guidelines than most medical specialties. Anesthesiologists have also benefited from the advent of safeguards such as continuous pulse oximetry and continuous mean arterial pressure and blood pressure monitoring systems. Notwithstanding the rigid guidelines and all the technologic advances, there are still serious preventable injuries, which occur and are entirely the responsibility of anesthesiologists. The one which I choose to address in this article will be airway management.
A completely healthy human being cannot survive more than a few minutes of apnea (absent ventilation) without suffering serious injury and in some cases severe brain damage or death. Nevertheless, at the beginning of every surgical procedure where inhalation anesthesia is to be employed, there is an intentional period of apnea artificially induced by the administration of paralytic drugs to enable the anesthesiologist to pass a tube through the oral pharynx into the trachea in order to secure the patient’s airway for the administration of assisted ventilation and inhalation anesthesia. Sometimes when the patient’s spontaneous ventilation have been intentionally eliminated by the use of paralytic drugs, there is difficulty in securing the airway and the anesthesiologist then experiences what most anesthesiologists regard as their worst nightmare (though it is truly a greater nightmare for the patient’s family). A patient’s ability to self ventilate has been eliminated intentionally and routinely. An airway cannot be passed or an airway is passed but a patient cannot be ventilated through the airway. The patient cannot self ventilate because of the paralytic agent. The patients dies. Alternatively, the patient is successfully ventilated ultimately but suffers severe brain damage because of the interval of apnea. The patient then subsequently either dies or is left in a comatose state.
In 1993, the American Society of Anesthesiologist’s Task Force on management of a difficult airway, promulgated practice guidelines for the management of the difficult airway which were published in the Journal of Anesthesiology, 78:597 (1993). First and foremost, it is the anesthesiologist’s responsibility during the course of a pre-operative anesthesia evaluation to assess the likelihood that a difficult airway will be encountered. Prior records are to be examined and a careful history is to be taken. There is a wide array of frequently encountered physical anomalies, which can be assessed and identified during the course of the pre-anesthesia evaluation. For a patient in whom a difficult intubation is anticipated, a specific strategy must be developed for how the difficult airway will be managed. One alternative, when a difficult airway is anticipated prior to a surgical procedure, is to not perform the surgical procedure or to perform it under regional or other form of anesthesia. In Pennsylvania a patient’s consent to anesthesia, where the patient has a difficult airway, cannot be informed consent, if the patient is not made aware of the hazards of proceeding with the surgery in the face of a difficult airway. In one of every ten thousand inhalation anesthesias an intubation effort fails and a patient cannot be ventilated and dies. For a patient with a difficult airway, the risk is a thousand times greater.
If the surgery is to be done under inhalation anesthetic, notwithstanding the risk, short-acting paralytic agents are to be given and the patient is to be pre-oxygenated to such an extent, they are easily (like a pearl diver) able to survive without harm a prolonged period of apnea. They can then await the return of their own spontaneous respiratory function after the short-acting paralytic agent has been metabolized. Awake intubation can also be attempted where the intubation is conducted without the use of paralytic drugs. Whatever method is employed initially, the anesthesiologist must be prepared before the procedure begins to deal with the possibility that awake intubation will be unsuccessful or that spontaneous ventilation will not effectively be restored. In teaching hospitals an experienced bronchoscopist must be immediately available for the placement of a tube by fiber optic bronchoscopic guidance. Transtracheal jet ventilation should be available so that a patient can be ventilated through a needle inserted through the cricoid cartilage into the trachea. It is important to remember that securing an airway surgically is not an effective viable alternative in most cases.
Though there are cases, to be sure, where well-prepared anesthesiologists observing every precaution have encountered an airway that could not be secured and ventilation that could not be recovered, it is in the opinion of this author most often the case that the loss of a patient before the commencement of surgery because of a failure to secure an airway is the result of the failure to have properly identified that a difficult airway existed or the failure to have properly prepared for a difficult airway in accordance with the accepted guidelines of recognized authorities in the field. For general reference on this subject look to Anesthesia, Editor, Ronald D. Miller, 5th Edition 2000, Complications in Anesthesiology, Editors Gravenstein and Kirby, 2nd Edition 1996, Clinical Anesthesia, Editors Burak, Cullen, Stoetling, 3rd Edition, 1997, and Anesthesia for Obstetrics, Editors Shnider and Levinson, 3rd Edition, 1993.