ANES 1302 Alcohol and Illicit Drugs

Preoperative Evaluation and Assessment

Alcohol and Illicit Drugs

  • Table 28-4: Effect of Acute and Chronic Substance Abuse on Anesthetic Requirements

    Substances Evaluated for Anesthetic Requirements

    1. Opioids: Highly effective analgesics that can lead to sedation and respiratory depression. They act primarily on the mu-opioid receptors in the central nervous system (CNS), altering pain perception. Common opioids include morphine, fentanyl, and oxycodone. They typically increase required anesthetic doses due to their effects on respiratory drive and airway reflexes.

    2. Barbiturates: These are CNS depressants that enhance the activity of gamma-aminobutyric acid (GABA), leading to sedation and anesthesia. They can decrease the threshold for seizures and are less commonly used today due to the availability of safer agents. Their effect can necessitate adjustments in anesthetic dosage, particularly in patients with a history of chronic use.

    3. Alcohol: Chronic alcohol use can lead to tolerance, requiring higher doses of anesthetics. Additionally, acute intake can cause significant interactions with anesthetic agents, increasing the risk of complications such as aspiration and endocrine disorders. Preoperative evaluation must assess alcohol consumption levels and consider supplementation with thiamine to prevent Wernicke's encephalopathy.

    4. Marijuana: Known for its psychoactive effects due to tetrahydrocannabinol (THC), marijuana can complicate perioperative management. It may affect cardiovascular function and interact with various anesthetics, potentially increasing the required doses.

    5. Benzodiazepines: These drugs, commonly used for anxiety and sedation, can potentiate the effects of other CNS depressants, necessitating careful dosage adjustments. They achieve their effect through modulation of GABA receptors.

    6. Amphetamines: Stimulants that increase the release of norepinephrine and dopamine, amphetamines can lead to increased heart rate and blood pressure, which must be monitored during anesthesia. Chronic use may lead to tolerance and significant cardiovascular effects.

    7. Cocaine: A potent stimulant that can cause altered cardiovascular dynamics, cocaine may increase myocardial oxygen demand while simultaneously decreasing myocardial blood flow. It is critical to consider this in anesthetic planning due to potential arrhythmias.

    8. Phencyclidine (PCP): Known for its dissociative anesthetic properties, PCP can complicate anesthesia due to its unpredictable effects on consciousness and movement. Its administration may lead to severe agitation postoperatively, requiring careful management.

    • Impact Classification:

      • 1: Increases required anesthetic dose

      • T: Associated with marked sympathetic stimulation

      • 0: No effect

      • ?: Unknown.

  • Opioid Administration:

    • Dilates venous capacitance and arteriolar vessels, causing modest reduction in arterial pressure.

    • Reduces heart rate without depressing left ventricular (LV) function or cardiac output.

    • Mechanism: Bind to mu2 receptors affecting respiratory drive and airway reflexes.

    • Side Effects: Potential for respiratory depression, sedation, and constipation, necessitating careful monitoring during administration.

Ongoing Effects of Alcohol and Illicit Drugs

Acute and Chronic Effects

  • CNS:

    • Toxicity leads to problems with consciousness, cognition, sleep disorders, and mental health issues (i.e., Wernicke-Korsakoff syndrome, dementia).

  • CVS:

    • Arrhythmias, alcohol-induced cardiomyopathy, and hypertension.

  • GI/HPB:

    • GERD, esophagitis, ulcers, and cirrhosis leading to various gastrointestinal issues.

  • Hematologic Effects:

    • Anemia, reduced WBC, and clotting factors due to bone marrow suppression.

  • Pulmonary Effects:

    • Increased risk of aspiration and compromised immune responses.

  • Anesthetic Considerations:

    • Preoperative: evaluation of CVS and CNS; supplementation of thiamine, folic acid, etc. to prevent complications.

    • Labs to check liver function and electrolytes.

    • Intraoperative: Assess risk for delayed gastric emptying.

Metabolism of Substances

Key Pathways

  • Two main pathways involved in the metabolism of substances:

    • Catechol-O-methyltransferase (COMT) catalyzed methylation.

    • Conjugation processes post-degradation (glycine conjugation).

Major Acute Syndromes

  • Exertional Hyperpyrexia & Rhabdomyolysis:

    • Includes symptoms like muscle rigidity and impaired consciousness, leading to multi-organ failure.

  • Serotonin Syndrome:

    • Presents with confusion, excess sweating, cardiovascular instability, and possible death due to hyperthermia.

  • Hyponatremia & Cerebral Edema:

    • Caused by excessive water intake and may lead to severe neurological impairment.