CHEMICAL DEPENDENCE

Drug addiction has long been an occupational hazard in the practice of medicine. In the late 19th century, Merck and Company began producing cocaine hydrochloride for commercial use. It was initially touted by Freud and others as a cure for alcoholism and morphine addiction, as well as an agent to increase endurance. ^[139] In 1884, Sir William Halstead (1852–1922) successfully injected cocaine into a sensory nerve trunk to create the first regional anesthetic, a discovery that not only revolutionized the practice of surgery but also marked the beginning of his lifelong struggle with drug addiction.^[140]

William Halstead attended Yale University and was captain of the football team before enrolling in Columbia University College of Physicians and Surgeons. After graduation in 1877, he studied medicine abroad before returning to the United States, where he eventually became one of the founding members of the Johns Hopkins University School of Medicine. His contributions to modern-day surgery are legendary. He is responsible for the introduction of antiseptic technique, surgical gloves, and vascular clamps into the practice of surgery. He performed the first total mastectomy for cancer and described the first hernia repair. Throughout his career, Halstead was addicted to morphine. His addiction was known at the time to close friends and colleagues, who tried in vain to help him overcome his habit. At the peak of his career he is said to have used in excess of 180 mg/day, and despite numerous attempts to quit, he was believed to be addicted until the time of his death in 1922. By all accounts, Halstead became addicted to morphine in his effort to cure his addiction to cocaine.^[140]

William Halstead's addiction to cocaine and morphine illustrates a number of characteristics that are often associated with drug addiction in anesthesiologists today. He was academically accomplished, his addiction began early in his career, he was a polydrug abuser, his addiction began with an element of curiosity, he had easy access to potent drugs, his addiction was initially discovered by friends, and his colleagues at work were the last to know.

The abuse potential of the psychotropic drugs used in the practice of anesthesia is well documented.^[141] Potent psychoactive drugs are readily available and familiar to anesthesiologists in the course of their daily practice. Even the inhaled drugs nitrous oxide and vapor anesthetics pose an abuse potential to health care workers with easy access to them. Zacny and Galinkin reported a case of an Air Force pharmacist court-marshaled during the 1991 Gulf War for abusing isoflurane. Not surprisingly, vapor anesthetics are abused when other more familiar drugs are not available. The National Household Survey on Drug Abuse estimates the recreational use of nitrous oxide and vapor anesthetics to be 2.2% and 0.3%, respectively, in the population older than 12 years. No doubt, familiarity and availability contribute to the recent reports of abuse of propofol by anesthesia caregivers. Although abuse of ketamine by anesthesiologists is not new, its recent increased recreational use at rave parties may contribute to increased occupational abuse in the future.^[141]

Today, drug abuse is a well-recognized occupational hazard in medical practice, and guidelines have been published to aid in its recognition and intervention. The goal of intervention is rehabilitation and eventual reentry into medical practice. This section provides information about chemical dependence in anesthesiologists and the steps required to help a colleague or yourself.

The Disease

The terminology in this section is based on recommendations of experts in the field of substance abuse.^[142] Addiction is the compulsive continued use of a substance

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A growing body of scientific evidence indicates that addiction is a chronic, relapsing disease resulting from the long-term effects of drugs on the brain.^[143] Acceptance of this fact is crucial for those dealing with chemically dependent physicians and other addicts. By considering an impaired colleague to be ill rather than an object of disdain, one will be better equipped to provide the initial guidance that the impaired physician needs.

During the 1980s, independent genetic, neurophysiologic, and biochemical observations demonstrated the complex etiology of addiction to drugs. For example, alcoholism is four times more common in the offspring of alcoholics than in appropriate controls and is related more to genetic than to environmental influences.^{[144] [145]} Familial transmission of drug addiction has also been documented.^[146] Alcoholics metabolize their drug of choice differently from nonalcoholics.^[147] In inbred strains of alcoholic rats, condensation products that form between alcohol metabolites and catecholamine precursors fit opiate receptors. Similar compounds in humans may be responsible for the opiate-like euphoria that some alcoholics report. ^[148]

It has been discovered that essentially all drugs of abuse work through a single pathway in the brain. The mesolimbic reward system, which extends from the ventral tegmentum to the nucleus accumbens with projections to other areas of the brain, is not only activated by drugs of abuse but is also irreparably altered by chronic exposure to these drugs. The molecular, structural, cellular, and functional changes that result from continued drug abuse are thought to be responsible for the relapses that frequently follow periods of abstinence. At the outset, drug abuse is a voluntary event. However, once these neural changes have begun to develop, it becomes an addiction that is characterized by compulsive, irrational drug-seeking behavior. A detailed presentation of these neurologic responses to chronic drug use, including upregulation of central cyclic adenosine monophosphate pathways in the locus caeruleus and the nucleus accumbens, alterations in drug receptor-G protein coupling, changes in gene expression, and modification of central neurotransmission, is beyond the scope of this chapter. The interested reader is encouraged to read several informative review articles, all of which appear in a single issue of Science. ^{[142] [149] [150] [151]}