Volume 1, No. 1 • Spring 1986

Is There Minimal Essential Monitoring??

I.S. Gravenstein, M.D.

WHAT MONRMRING did Dr. W.T.C. Morton use during the first surgical operation under ether anesthesia October 16, 1846? (Also, what were his malpractice insurance premiums?)

Groups Publish Conventions

Physicians and nurses who devote their work to the practice of anesthesia have one common goal, namely to make anesthesia as safe for their patients as humanly possible. Despite these efforts the occasional disaster occurs and a patient suffers harm. Whenever this happens, an agonizing search begins: what could have been done to prevent the problem.

Of all the many steps that have been recommended to make anesthesia safe, few are universally accepted; indeed the measures urged by some for adoption as essential safety precautions are considered by others as being not all that helpful. For example, the esophageal (or precordial) stethoscope has been praised as being a wonderful monitor. It requires no electricity and is therefore immune to power outages and electrical artifacts. It allows the anesthetist to listen without interruption to heart sounds and breath sounds. Thus it becomes a monitor that alerts the anesthetist to the cardiac standstill as well as the disconnected ventilator. Indeed, it can help with more subtle diagnoses, such as the muffled cardiac sounds of a depressed heart or the wheezes of bronchospasm.

How could anyone denigrate the esophageal or precordial stethoscope? The critics love to recount stories in which the anesthetist failed to notice that breath and heart sounds had suddenly disappeared when the tube from chest to ear was furtively clamped. So what good is a monitor that depends solely on the attention of a human being who can be distracted or can become so inured to a monotonous sound that he no longer notices when the sound vanishes?

Clinical examples

Let us ask if we can identify monitors American anesthetists would agree on calling essential. Let us define as essential any monitor that would cause us to cancel an elective case should neither the monitor nor an equivalent be available. Let us also agree to focus on simple, short anesthetics in healthy patients. For example, imagine a general anesthetic needed for the placement of myringotomy tubes in a six year old boy, or a saddle block in a healthy 20 year-old man in lithotomy position for a hemorrhoidectomy.

A skilled anesthesiologist or anesthetist must be present in the operating room. Beyond that the question becomes more difficult to answer because now we have options. Those who insist on watching an ECG monitor and recording the arterial blood pressure might be challenged by others who say that a precordial stethoscope and a pulse oximeter could adequately replace the ECG and blood pressure monitor in healthy, young patients. Some might insist on monitoring the temperature, others would be satisfied with having a thermometer available should clinical suspicion call for a temperature measurement. Some insist on an oxygen analyzer in the breathing circuit, others are prepared to omit one when they use a Bain circuit. When the patient is awake, some believe that verbal communication maintained with the patient is as good a monitor as any, because an alert patient clearly demonstrates good cerebral perfusion and oxygenation. So where should the line be drawn? Should it be left to the judgment of every individual anesthetist?

Current Recommendations

While the majority of us still practice as we have been taught and as our clinical experience dictates, others have formed groups and in laborious discussions have developed monitoring conventions to which they plan to adhere. There are, for instance, the “Guidelines for Patient Care in Anesthesiology” developed and endorsed by the Arizona Society of Anesthesiologists, dated February 23, 1985. These recommend for patients undergoing general anesthesia:

1) Oxygen analyzer with low concentration alarm in the circuit.

2) Low pressure alarm on the anesthesia ventilator if used during the course of the anesthetic.

3) Two of the following three modalities.-

a) intermittent or continuous blood pressure monitoring

b) continuous electrocardiographic display

c) precordial esophageal stethoscope-

The Department of Anesthesia of the Harvard Medical School adopted on March 25, 1985 and revised on July 3, 1985 its “Standards of Practice 1; Minimal Monitoring” which include for preplanned anesthetics administered in designated anesthetizing locations where not clinically impractical.

Blood Pressure and Heart Rate

Every patient receiving general anesthesia, regional anesthesia, or monitored intravenous anesthesia shall have arrival blood pressure and heart rate measured at least every five minutes where not clinically impractical.


Every patient shall have the electrocardiogram continuously displayed from the induction or institution of anesthesia until preparing to leave the anesthetizing location, where not clinically impractical.

Continuous Monitoring

During every administration of general anesthesia, the anesthetist shall employ methods of continuously monitoring the patient’s ventilation and circulation. The methods shall include, for ventilation and circulation each, at least one of the following or the equivalent.

For ventilation-palpation or observation of the reservoir breathing bag, auscultation of breath sounds, monitoring of respiratory gases such as end-tidal CO, or monitoring expiratory flow.

For circulation-palpation ofa pulse, auscultation of heart sounds, monitoring of a tracing of in&a-a,rtetial pressure, pulse plethysmography, or ultrasound peripheral pulse monitoring.

Breathing System Disconnect Monitoring

When ventilation is controlled by an automatic mechanimi ventilator, them shall be in continuous use a device that is capable of detecting disconnection of any component of the breathing system. ne device must give an audible signal when its alarm threshold is exceeded.

Oxygen Analyzer

During every administration of general anesthesia using an anesthesia machine, the concentration of oxygen in the patient breathing system will be measured by a functioning oxygen analyzer with a low concentration limit alarm in use.

Ability to Measure Temperature

During every administration of general anesthesia there shall be readily available a means to measure the patient’s temperature.

More recently another group with representatives from industry and anesthesia, the Anesthesia Safety Consortium, drafted a set of recommendations designed to reduce the incidence of problems related to inadequate oxygenation of patients. The monitors that were recommended included: 1) an in-circuit oxygen analyzer with low alarm 2) capnography 3) means for the measurement oft the patient’s oxgenation 4) means for the detection of undesirable airway pressure, both high and low.

What will you do clinically?

Let us now return to our patients and ask again, what monitors should we demand for our patients to have general anesthesia or a saddle block? We can answer the question with assurance if we are willing to embrace one or the other set of conventions. But which one? We will search in vain for scientific evidence demonstrating that this or that convention will indeed improve the lot of our average patient. Nevertheless, such conventions prepared by recognized experts, published by widely respected groups and obviously drawn up with the best of intentions of improving the safety of anesthesia will assume a life of their own. Ignoring such conventions will cause critics to ask whether applying those conventions could possibly hurt and whether they might not indeed help? And once we have to admit that they might, in fact, be helpful in reducing adverse incidents in anesthesia, we have taken the first step toward adopting them ourselves.

With the publication of these first conventions, we are entering a new phase in anesthesia. Can we expect the formulation and adoption of national conventions? It is too early to predict in detail the practices and monitors that are going to be included in such a national effort. But many assume that for the first time we will have minimal essentials that will influence our practice.

On the one hand, we will see much more uniformity in the practice of anesthesia. On the other, for the first time them will be occasions when we will say, sorry, I have to delay this case until this monitor has been repaired. Of course, there will have to be alternatives in emergencies or in clinical circumstances where one or the other convention cannot be met. But we will be expected to justify and document deviations from the conventions.

It is a fair bet that the monitoring modalities mentioned in the first guidelines published by the Arizona group, the standards of the Harvard Department, and the recommendations of the Patient Safety Consortium are going to come under close scrutiny for inclusion in any list of minimal essentials. The Anesthesia Patient Safety Foundation will closely examine proposed monitoring conventions and it will also tap the enormous clinical experience represented by the thousands of anesthesiologists and nurse anesthetists who practice in the United States. Therefore, the Foundation needs to hear from you! Please write and tell us your ideas on how to make anesthesia as safe as possible for the patients entrusted to our care.

I.S. Gravenstein, M.D.

For the Executive Committee

Anesthesia Patient Safety Foundation