Opioid Analgesics
Opioids are natural and synthetic substances related to opium derived from poppies.6,7 Heroin, first synthetically derived from morphine in the 1870s, is abused by injection, inhalation, or smoking.6 Opioids (i.e., codeine, fentanyl, hydrocodone, hydromorphone, methadone, morphine, oxycodone, and oxymorphone) are used to treat acute and chronic pain. Pain relief occurs from the opioids’ effect primarily on the opioid receptors (mu, kappa, delta) in the CNS. Over the past two decades, opioids have been more widely used for the treatment of not only acute pain but also chronic pain.7 Illicit use of prescription opioids has increased as well, and opioids are only second to marijuana in substances used for nonmedical purposes.1 Tolerance to these drugs and a cross-tolerance with opioid analgesics develops over time. Use of continuous opioids after 2 to 10 days can cause a physical dependence and precipitate acute withdrawal symptoms.7
Individuals with a history of substance abuse may be treated for addiction with methadone (pure mu-agonist opioid), buprenorphine (partial opioid agonist), or naltrexone (a mu antagonist).8 For these individuals, a care plan should be developed before surgery. Patients receiving methadone should continue to do so in the perioperative setting.9 Multiple recommendations exist for the treatment of the patient on buprenorphine therapy. If the surgery is not emergent, the most common approach is to wean the buprenorphine at least 72 hours before surgery, replace with methadone, and restart buprenorphine after the surgical recovery. If buprenorphine is not discontinued, increased opioid dosing will be necessary to provide adequate pain relief due to the partial agonist effect of buprenorphine.10 Naltrexone which can be delivered either orally (daily) or intramuscularly (monthly) blocks the opioid receptors. Oral naltrexone should be discontinued 72 hours prior to surgery and intramuscular injection discontinued one month prior to surgery. If emergent surgery is necessary, one may have to use10-20 times the usual dose of opioids to effectively overcome the antagonism from naltrexone.8
CNS effects of opioids are mental status changes and respiratory depression. Heroin overdose can cause noncardiogenic pulmonary edema.6 Cardiovascular effects can be a result of injection use of opioids, which can lead to endocarditis. Methadone has been associated with electrocardiogram prolonged QTc and increased risk of torsades de pointes.6 Signs of opioid withdrawal include mydriasis, piloerection, sweating, increase in pulse and blood pressure, diarrhea, abdominal cramping, and diffuse bone and muscle pain. The patient may also experience increased irritability, anxiety, and insomnia.11 Acute opiate withdrawal is not dangerous to life because it usually is not associated with seizures or delirium.
Nursing Care
Perianesthesia nursing care of a patient taking prescription opioid analgesics, methadone, buprenorphine, or heroin focuses on monitoring for effects of opioid overdose or acute withdrawal (abstinence) syndrome. Individuals who use opioids on a regular basis or those actively using heroin are at risk for withdrawal symptoms during the perioperative period and may require higher doses of opioid analgesics both to control the pain and to prevent withdrawal.9 Treatment for acute opiate withdrawal is administration of any opioid analgesic. Interventions to treat withdrawal symptoms such as the use of clonidine and benzodiazepines9 will most likely not be done during the acute postoperative phase. The perianesthesia nurse must use caution in the coadministration of opioids and benzodiazepines due to the risk of oversedation.
If a patient is suspected of opioid dependence, opioid antagonists such as naloxone (Narcan) should not be administered unless absolutely necessary for respiratory depression because withdrawal syndrome can be precipitated. No attempt should be made to induce opioid withdrawal of the patient who is actively dependent during the postanesthesia care unit period.9,12 Multimodal analgesia including nonsteroidal antiinflammatory drugs, acetaminophen, gabapentinoids, and local anesthetics is the foundation of acute pain management.10,12,13 The use of multimodal analgesia is especially important for individuals with histories of substance use disorder, those on maintenance therapy, and those on chronic opioids who may not achieve effective pain management with opioid monotherapy.
Central Nervous System Depressants
Alcohol has been used for longer than recorded history and is second only to the use of caffeine.14 At lower blood levels, alcohol is a CNS depressant, and at higher blood levels, it is a sedative hypnotic and may increase the frequency of apneic episodes.14 Used as one of the first anesthetics, alcohol can produce anesthesia, respiratory depression, and hypotension.15 Alcohol causes disinhibition, which can cause talkativeness and increased confidence but in some individuals can evoke violent behavior.14
Individuals under the influence of alcohol may be at increased risk for aspiration due to impaired airway reflexes and decreased gastric motility. Previously, it was thought that persons with chronic alcohol abuse may require higher anesthetics, but no large-scale studies have demonstrated that there are different anesthetic needs. However, in those with alcoholic liver disease, there may be alterations in drug metabolism that could affect responses to anesthesia and analgesia. Patients under the influence of alcohol may be uncooperative during emergence from anesthesia.16
Alcoholism can cause liver cirrhosis, which causes abnormal hepatic circulation. Individuals with cirrhosis may have coagulopathies, gastrointestinal bleeding from esophageal varices, and renal insufficiency. These individuals may be hypoxic due to hepatopulmonary syndrome and pulmonary hypertension. Patients with cirrhosis are high surgical risks. Mortality is most often due to hemorrhage, sepsis, and hepatorenal syndrome. Due to decreased hepatic blood flow caused by anesthetic agents, the hepatic system can be even more compromised.9
Nursing Care
In the perianesthesia setting, nurses must assess for alcohol abuse and withdrawal syndrome and treat appropriately.9,17 The revised Clinical Institute Withdrawal assessment of alcohol scale (CIWA-aR) can help nurses recognize and respond to patients’ alcohol withdrawal.18 Withdrawal from alcohol starts 6 to 24 hours after the last drink. 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 signs and symptoms of this syndrome usually disappear within 48 hours without treatment.9
Severe withdrawal syndrome should be suspected if the patient experiences restlessness, disorientation, tremulousness, and hallucinations. In addition, symptoms such as diaphoresis, hyperpyrexia, tachycardia, and hypertension are seen because of activation of the sympathetic nervous system.17 Seizures occur about 24 hours after the last drink. Delirium can occur between 24 and 36 hours after the last drink.17
Life-threatening delirium tremens, which is rare (mortality less than 1%), is a combination of delirium with symptoms such as tachycardia, fever, hyperthermia, and tremor that generally does not appear until about 72 to 96 hours after the last drink.17 Although this may not be of immediate concern in the perianesthesia setting, some patients may be in this window of time, and thus the perianesthesia nurse should recognize and be able to treat this serious condition.
Treatments to control the withdrawal symptoms include sedation with benzodiazepines such as diazepam, chlordiazepoxide, and lorazepam,9 which can also prevent seizures and delirium. Antiseizure medications may also be utilized in addition to benzodiazepines as adjuncts. Beta-blockers such as propranolol or alpha-adrenergic agents such as clonidine may be utilized for autonomic manifestations. Thiamine replacement is essential as patients with alcohol abuse are often deficient in this vitamin, which can lead to Wernicke-Korsakoff syndrome, which is a neurologic emergency.17
Special considerations need to be given to patients who may be receiving naltrexone either daily or as a monthly depot for alcohol abuse. If alcohol abuse is suspected during the nursing assessment, the nurse should also assess if the patient is receiving naltrexone treatment. Naltrexone, an opioid antagonist, will block the effects of opioids commonly used to treat postoperative pain. Those patients taking oral naltrexone should discontinue it 3 days before surgery. Those who receive the monthly depot injection should wait a month before an elective surgery. For those patients who have an emergent surgery, higher doses of opioids may need to be given, and acute pain management should include nonopioid analgesics.9
Central Nervous System Sedative Hypnotics
Medications in this class include barbiturates, benzodiazepines, nonbenzodiazepine sedative hypnotics (sleep aids), muscle relaxants, and anticonvulsant medications, all of which decrease CNS activity. Although barbiturates were the first preparations in this class, they are not as widely used as benzodiazepines.19 In 2010, more than 400,000 visits to the emergency room were related to the use of benzodiazepines, which is only second to the misuse of opioids. A high percentage of overdose deaths from prescription drug abuse involve opioids with benzodiazepines.1
Complications during surgery in patients taking benzodiazepines are not widely reported.20 Patients who take benzodiazepines intermittently may experience withdrawal effects. However, long-term benzodiazepine treatment may put patients at risk for life-threatening acute withdrawal manifested as grand mal seizures, which may be precipitated 24 to 48 hours after discontinuation.19
Nursing Care
The perianesthesia nurse must assess for signs of benzodiazepine overdose as well as withdrawal. Overdose symptoms are similar to those seen in patients with alcohol abuse such as incoordination and speech slurring that can progress to coma. Managing overdose first involves airway protection. Flumazenil (Romazicon), a benzodiazepine receptor antagonist, is the reversal agent for benzodiazepine overdose. However, it must be used with caution in patients who are benzodiazepine-dependent as reversal of benzodiazepines is associated with precipitating the withdrawal syndrome including seizures.21 Signs of withdrawal can include the constellation of symptoms seen in alcohol withdrawal: tachycardia, hypertension, anxiety, insomnia, diarrhea, nausea, and more seriously, seizures.21 If a patient is going through withdrawal, benzodiazepines should not be discontinued in the acute perianesthesia setting. The nurse should notify the attending clinician if withdrawal is suspected to ensure that the patient does not experience serious effects such as seizures.
Central Nervous System Sympathomimetics
CNS sympathomimetics include natural alkaloids such as cocaine, ephedra, and khat as well as synthetic compounds such as “bath salts,” methamphetamine, methylphenidate (i.e., Ritalin) and amphetamines. These stimulants inhibit the reuptake of the catecholamines: norepinephrine and dopamine.22 Although cocaine is used legally as a topical or local anesthetic, it is most commonly used illicitly in the form of smoking, inhalation, or injection. Cocaine can contain many contaminants that can cause side effects. Ephedra or the synthetic ephedrine also cause a stimulating effect and lead to cardiovascular and CNS effects. Khat, a stimulant plant, has been used socially such as caffeine in East Africa. Methamphetamine is produced in home laboratories using over-the-counter pseudoephedrine and thus there are now more controls on its purchase at pharmacies.22 Synthetic illicit or over-the-counter stimulant preparations known as “bath salts” have had a dramatic rise in abuse. Prescription stimulants such as methylphenidate or amphetamines are used for treatment of attention deficit disorder but are also drugs of abuse.
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