Opioid analgesics

Opioid analgesics cause strong psychological dependence. Physical dependence is manifested by the withdrawal syndrome of autonomic storm and CNS irritability. A strong tolerance for these drugs and a cross tolerance with other drugs of the same classification of opioid analgesics develop. Studies indicate that in people who are chronically addicted to opioid analgesics such as morphine, the minimum alveolar concentration of inhalation anesthetics (see Chapter 20) is increased, which indicates that a cross tolerance with general inhalation anesthetics may exist.^7,8

Heroin, an opioid analgesic that is derived from morphine, is degraded in the body to morphine approximately 30 minutes after injection. The most common problem associated with the use of heroin and other opioid analgesics is pulmonary edema; other dysfunctions include superficial bacterial infections, adrenal insufficiency, bacterial endocarditis, liver disease, urinary abnormalities (proteinuria and glycosuria), and false-positive serology. In addition, approximately 30% of the persons dependent on opiates have positive results on the Venereal Disease Research Laboratory test for syphilis, but approximately 25% of these results are true positive when checked with the Treponema immobilization test.

Perianesthesia nursing care of a patient who is dependent on an opiate, such as heroin dependency, focuses on monitoring the patient for complications.³ Monitoring for the withdrawal (abstinence) syndrome is the foremost concern. The abstinence syndrome after dependence on an opiate occurs in two phases. The acute phase occurs during the first few days. The protracted phase, which is not readily treatable, can persist for as long as 2 to 6 months. The acute opiate abstinence phase is not dangerous to life because it usually is not associated with convulsions and delirium. Instead, the symptoms are anxiety, nervousness, jittery behavior, anorexia, rhinorrhea, hypotension, muscle twitching, insomnia, sweating, pupillary dilation, gooseflesh, nausea, and vomiting. Symptoms during the protracted phase include those of the acute phase, along with convulsions and delirium. Treatment for the acute opiate abstinence phase is accomplished with any opioid analgesic; reports indicate that clonidine has proved to be most effective in attenuating the symptoms. New research indicates that dexmedetomidine may also be effective in attenuating the symptoms. Treatment for the protracted phase focuses on protection of the patient and abatement of the symptoms shown by the patient. If a patient is suspected of dependence on an opiate, opioid antagonists such as naloxone (Narcan) should not be administered because the withdrawal syndrome can be precipitated. No attempt should be made at withdrawal of the patient who is actively dependent on an opiate during the postanesthesia care unit (PACU) period. Liberal use of morphine or methadone in the PACU appears to be satisfactory. Patients who are formerly dependent on opioids should not receive opioids; analgesics such as pentazocine (Talwin) and butorphanol (Stadol) should be used in their place. Nonsteroidal antiinflammatory drugs may also be considered in a multimodal approach for these patients.⁶

General central nervous system depressants

The patient dependent on a barbiturate may appear only nervous and anxious before surgery; however, the patient should be monitored after surgery for anxiety, tremors, and hallucinations. These symptoms usually develop on the second or third postoperative day and can be treated with a barbiturate until acute illness has passed. These patients also appear to have an increased tolerance to anesthesia and therefore have an increased chance of anesthetic toxicity.

The dependency rate of persons taking benzodiazepine compounds has increased significantly during the last decade. The benzodiazepine drug is usually taken in combination with marijuana or alcohol to obtain a high. Chronic intoxication has been reported with the use of these compounds. The benzodiazepine that produces the most dependency is diazepam (Valium); however, midazolam (Versed) will soon rank at the same level as diazepam. These drugs are becoming popular because of their rapid onset of action coupled with their pleasure-giving effects. The pharmacologic effects of the benzodiazepines are similar to those of the barbiturates.⁹ This classification of drugs is somewhat addictive and includes withdrawal syndromes.

For treatment of mild to moderate overdoses of benzodiazepines, the drug physostigmine in an adult dosage of 1 to 2 mg given intravenously can be used. Flumazenil (Romazicon), is a true benzodiazepine receptor antagonist with longer action and fewer side effects. The usual adult dose is 0.1 to 0.2 mg given intravenously. As with naloxone for patient dependence on an opioid, flumazenil must be used with caution with patients who are benzodiazepine dependent. More specifically, reversal of benzodiazepine dependence is associated with precipitating the withdrawal syndrome, including seizures (see Chapter 21).

Alcoholism has long been widespread, but it is difficult to define. An alcoholic, for the purposes of this discussion, is a person who is excessively dependent on alcohol and who has developed a noticeable degree of mental, physical, psychologic, or pathologic disorders. Alcohol was the first anesthetic; it can produce anesthesia, respiratory depression, and hypotension. Alcoholic dependency has been linked to complications during the perianesthesia phase including alcohol withdrawal syndrome, increased infections, acute respiratory distress syndrome, cardiovascular complications, and secondary hemorrhage.⁶

Alcohol affects many of the body’s major systems.¹⁰ Cirrhosis of the liver is common in the later stages of alcoholism. This knowledge is of importance to the perianesthesia nurse because the liver detoxifies many drugs administered during the perioperative period (see Chapter 16). Hepatic cirrhosis can produce significant alterations in pulmonary and cardiovascular functions. Hyperventilation and arterial oxygen desaturation are common findings caused by an increase in shunting of blood away from areas in the lung where diffusion of oxygen occurs. Concomitant with this is an increase in blood volume that can lead to cardiac hypertrophy and eventually to congestive heart failure. Fluid balance is affected by the presence of alcohol, because alcohol exhibits antidiuretic effects by inhibiting the release of antidiuretic hormone. Alcoholic cirrhosis (Laënnec’s cirrhosis) is also associated with portal vein hypertension, renal failure, hypoglycemia, duodenal ulcer, esophageal varices, and hepatic encephalopathy.

The alcoholic, in comparison with the nonalcoholic, usually requires a larger amount of sodium thiopental for induction and a higher concentration of anesthetic agents during surgery. Prediction of the time or the character of emergence from anesthesia is difficult in the alcoholic patient. This patient may be anxious and may have a stormy emergence and postoperative phase.

During the PACU phase, the alcoholic patient should be monitored for withdrawal symptoms. The minor alcohol withdrawal syndrome is characterized by symptoms such as tremulousness, insomnia, and irritability. Because of autonomic nervous system imbalance, signs such as tachycardia, hypertension, and cardiac dysrhythmias are often observed. The minor alcohol withdrawal syndrome can occur within 6 to 8 hours after abstinence by the alcoholic patient. The signs and symptoms of this syndrome usually disappear within 48 hours without treatment.