Anesthesia for Addict Patients

Abstract

Opium poppies are believed to have been first grown in the region near modern-day Iraq as early as 3400 B.C. Opium was used primarily as an analgesic and anesthetic, but medical use did not become widespread until the development of the hypodermic needle in the early 1800s Prescription opioid analgesic abuse is the fastest growing form of drug abuse in the US.Abused prescription opioids include hydrocodone (Vicodin, Lortab), oxycodone (Percocet, OxyContin), hydromorphone (Dilaudid), fentanyl (Duragesic, Fentora), and others. Drug addiction is a chronically relapsing disorder characterized by compulsion to seek and take drug(s) regardless of the adverse consequences that may ensue Addiction develops as a result of interactions between the availability, cost, and pharmacology of a drug of abuse, environmental and psychosocial factors (e.g., occupation, peer group), genetic predisposition, comorbid psychiatric disorders, and drug exposure. Addiction has a highly variable clinical course. Initial drug use is voluntary behavior, and most users do not develop drug-dependence. However, repetitive drug exposure in a susceptible individual appears to cause fundamental changes in central nervous system function that produce the disease. Experimental evidence suggests that genetic predisposition to addiction may be related to alterations in neurocircuitry that enhance sensitivity to the reinforcing effects of drugs of abuse, thus overwhelming cognitive control of behavior Opioid receptors are a group of G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. Opiate receptors are distributed widely in the brain, and are found in the spinal cord and digestive tract Opioid Agonists, the most widely used opioid analgesics are the pure agonists, and all of these are relatively selective for µ opioid receptors. Opioid antagonists act as competitive antagonist at all opioid receptors, but it has greatest affinity for µ receptors. Small doses of naloxone reliably reverse or prevent the effects of pure opioid agonists and most mixed agonist–antagonists. The block is reversible and competitive, so it can be overcome by additional agonist The Agonist–antagonist opioids are synthetic and semisynthetic analgesics that are structurally related to morphine. All these compounds produce some degree of competitive antagonism to morphine and the other pure agonists. Anesthesia providers have a greater risk for becoming addicted than other physicians because they have ready access to drugs that they personally can either administer to patients or divert for their own abuse. Chronic hypoxemia and reactive pulmonary arterial vasoconstriction resulting from interstitial fibrosis may also contribute to the development of pulmonary hypertension or cor pulmonale under these conditions. Bullous emphysema has been reported as another chronic complication of talc granulomatosis in intravenous opioid abusers.Septic pulmonary embolism is a frequent complication of injection drug abuse that may occur as a result of thrombophlebitis at the injection site or more commonly, tricuspid valve endocarditis. Mycotic aneurysms also occur as a consequence of seeding of the pulmonary vasculature with septic thromboemboli, and rupture of a pulmonary mycotic aneurysm may cause life-threatening hemoptysis. Anesthetic requirements for substance abusers vary depending on whether the drug exposure is acute or chronic. Elective procedures should be postponed for acutely intoxicated patients and those with signs of withdrawal. Regional anesthetics should be considered when possible. For general anesthesia, a technique primarily relying on a volatile inhalational agent may be preferable so that anesthetic depth can be readily adjusted according to individual need.