Anesthesia: Going Under Safely

by Food and Drug Administration (FDA)

The scene is a northern California teaching hospital. The patient is 65 years old and weighs 154 pounds. He is to undergo a mastoidectomy — an operation to remove part or all of the rear of the temporal bone, located behind the ear. He has a history of mild to moderate chronic obstructive pulmonary disease, he suffers from chest pains with moderate exertion, and has high blood pressure. He takes nadolol, a drug that reduces heart rate and cardiac output, and hydrochlorothiazide, a diuretic, to lower his blood pressure.

A preoperative physical examination uncovered nothing abnormal. The anesthesiologist learned the patient uses alcohol only moderately, does not smoke, and is taking no antidepressants or other drugs that might interfere with the way the body processes anesthetics. The patient has no history of adverse reactions to any anesthesia and no observable physical problems that might interfere with the anesthesiologist's work, such as a receding chin or a thick neck — both of which can lead to difficulty in inserting the breathing tubes used in general anesthesia.

The anesthesiologist is a second-year resident. Based on what she has learned about this patient and the planned operation, she has selected the anesthetic drugs and technique she plans to use and has gone over it all with her instructor.

The equipment she is about to use to administer the anesthetic and support the patient's life and vital functions during the procedure is now checked out. It includes an anesthesia gas machine and a ventilator — a machine that will pump oxygen and anesthesia gases to the patient's lungs through an endotracheal tube placed in the patient's windpipe with the aid of a laryngoscope — a tubular instrument used to look into the interior of the larynx.

There is a mass spectrometer, a device that detects and analyzes the volume and composition of gases the patient breathes in and out; a monitor to measure heart rate and rhythm; and a blood pressure monitor, the traditional sphygmomanometer with its pressure cuff for the arm. There is a monitor for the patient's temperature. Its probe will be positioned in the patient's esophagus. Another instrument, a pulse oximeter, calculates and displays the oxygen content in the blood through a sensor placed on a finger or clipped to an earlobe. A capnograph will measure exhaled carbon dioxide. It will warn if the patient is not ventilating adequately as well as give an immediate indication of accidental disconnection of breathing tubes.

Poles are in place to support bottles filled with intravenous fluids. Flexible pipes to the wall of the room carry oxygen and nitrous oxide gas to the anesthesia gas machine from a hospital central supply. Backup tanks of the gases are attached to the machine, should the central supply fail. Also nearby is an anesthesia supply cart that contains all necessary drugs, plus the ones the anesthesiologist hopes will not be necessary but keeps ready for an emergency during the operation. (For more on the types of drugs used in anesthesia, see "Anesthesia: A Long Way from Biting Bullets" in the June 1984 FDA Consumer and "Gases Are Drugs, Too" in the May 1982 FDA Consumer.

The checkout has taken perhaps 15 minutes and ends about the time the patient is wheeled into the operating suite. The resident again takes the patient's vital signs. Blood pressure, read from the cuff now inflated around his arm, displaces 145 millimeters of mercury when his heart pumps and 95 mm when it relaxes (a blood pressure reading of 145/95). His heart is beating 75 times a minute.

The Pace Quickens

The resident-anesthesiologist now picks up the pace of her work. She inserts an intravenous line into the patient's arm and goes on to administer sodium thiopental (a fast-acting barbiturate) to induce sleep and a narcotic (such as fentanyl) to block pain. The patient also is briefly paralyzed with another drug (such as succinylcholine chloride), to make it easier to insert the breathing tube.

After again checking vital signs and determining the patient is unconscious and relaxed, the resident will soon begin to guide an endotracheal tube into his windpipe. She turns valves that control the flow of gases — oxygen and nitrous oxide to support life, and halothane, enflurane or isoflurane to deepen the anesthesia, maintain amnesia, and eliminate pain. The anesthetic also depresses respiration and reflexes and may lower blood pressure.

As the operation gets under way, the resident's eyes and hands are in nearly constant motion, checking vital signs, touching dials, tapping hoses, and touching the patient. Her mind becomes full of the sound of the ventilator breathing for the patient. She strives to be "in tune" with the patient — vigilant for any measurable or intuitive warning that something is going wrong. His life is in her hands.

30 Million Times a Year

Similar scenes play out around the clock in hospitals across the United States as wounds are repaired, physical deformities or abnormalities are corrected, diseases are managed, and organs are repaired or replaced. People also are being "put to sleep," or given regional or local anesthetics when they are more appropriate, in clinics and the offices of medical and dental specialists. This all adds up to as many as 30 million anesthesia procedures each year, according to the American Society of Anesthesiologists. Most are near-routine work for the 30,000 professional anesthetists, including anesthesiologists (physicians specifically trained in this field) and nurse anesthetists (registered nurses who are nationally certified in anesthesiology). Their tools include approximately 36,000 anesthesia machines. The basic cost of each device is about $50,000.

Of the 30 million times a year someone undergoes anesthesia in surgery, the overwhelming majority of the patients will have an uneventful experience.

The safety record for modern anesthesia is remarkable. Over the past 20 years it is generally estimated the death rate ran between 1 and 5 deaths per 10,000 anesthetics given. More recently, however, there is evidence the anesthetic death rate in the western world may be as low as 1 per 200,000 or more anesthetics given, according to Ellison Pierce Jr., M.D., of the Harvard Medical School, who also is head of the Anesthesia Patient Safety Foundation, Park Ridge, Ill.

Cooperating for Safety

The Food and Drug Administration works closely with medical professionals and medical device manufacturers to reduce the risk involved in anesthesia. FDA's Center for Devices and Radiological Health regulates the manufacturers of anesthesia machines, ventilators, breathing systems, and other machines used in anesthesiology. FDA's Center for Drug Evaluation and Research reviews and approves drugs as safe and effective. FDA also has an important role in promoting the safe use of medical devices through education. FDA produces educational documents and audiovisual materials and conducts conferences and workshops, addressing the needs of health professionals, consumers, patients and manufacturers. As part of this process, FDA has been working with health professionals and device manufacturers to solve problems involving unsafe or ineffective use of anesthesia equipment.

"We realize that device safety and effectiveness are not achieved if medical device users make mistakes in their proper operation," Joseph S. Arcarese, director of the CDRH Office of Training and Assistance told the Regulatory Affairs Professionals Society at its 12th annual meeting in Alexandria, Va., in September of 1988.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.