Physostigmine reversal of antihistamine-induced excitement and depression

Anesthetic Management of Narcolepsy Patients During Surgery: A Systematic Review

BACKGROUND

Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness, sleep paralysis, and/or hypnagogic/hypnopompic hallucinations, and in some cases cataplexy. The response to anesthetic medications and possible interactions in narcolepsy patients is unclear in the perioperative period. In this systematic review, we aim to evaluate the current evidence on the perioperative outcomes and anesthetic considerations in narcolepsy patients.

METHODS

Electronic literature search of Medline, Medline in-process, Embase, Cochrane Database of Systematic Reviews databases, international conference proceedings, and abstracts was conducted in November 2015 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols guideline. A total of 3757 articles were screened using a 2-stage strategy (title-abstract followed by full text). We included case studies/series, cohort studies, and randomized controlled trials of narcolepsy patients undergoing surgical procedures under anesthesia or sedation. Preoperative narcolepsy symptoms and sleep study data, anesthetic technique, and perioperative complications were extracted. Screening of articles, data extraction, and compilation were conducted by 2 independent reviewers and any conflict was resolved by the senior author.

RESULTS

A total of 19 studies including 16 case reports and 3 case series were included and evaluated. The majority of these patients received general anesthesia, whereas a small percentage of patients received regional anesthesia. Reported complications of narcolepsy patients undergoing surgeries were mainly related to autonomic dysregulation, or worsening of narcolepsy symptoms intra/postoperatively. Narcolepsy symptoms worsened only in those patient populations where the preoperative medications were either discontinued or reduced (mainly in obstetric patients). In narcolepsy patients, use of depth of anesthesia monitoring and total intravenous technique may have some advantage in terms of safety profile. Several patients undergoing neurosurgery involving the hypothalamus or third or four ventricles developed new-onset narcolepsy.

CONCLUSIONS

We found a paucity of prospective clinical trials in this patient population, as most of the studies were case reports or observational studies. Continuation of preoperative medications, depth of anesthesia monitoring, use of multimodal analgesia with short-acting agents and regional anesthesia techniques were associated with favorable outcomes. Obstetric patients may be at greater risk for worsening narcolepsy symptoms, possibly related to a reduction or discontinuation of medications. For neurosurgical procedures involving the hypothalamus or third and fourth ventricle, postoperative considerations should include monitoring for symptoms of narcolepsy. Future studies are needed to better define perioperative risks associated with anesthesia and surgery in this population of patients.

Psychiatric side effects of medications prescribed in internal medicine

Several pharmacological treatments used in internal medicine can induce psychiatric side effects (PSEs) that mimic diagnoses seen in psychiatry. PSEs may occur upon withdrawal or intoxication, and also at usual therapeutic doses. Drugs that may lead to depressive, anxious, or psychotic syndromes include corticosteroids, isotretinoin, levo-dopar mefloquine, interferon-a, and anabolic steroids, as well as some over-the-counter medications. PSEs are often difficult to diagnose and can be very harmful to patients. PSEs are discussed in this review, as well as diagnostic clues to facilitate their identification.

Effects of cholinomimetics on cocaine-induced hypotension and apneusis at a ventral brainstem cardiorespiratory control site

The current study was undertaken to evaluate the effects of cholinomimetic drugs on cocaine-induced central cardiorespiratory depression. Cats anesthetized by urethane (2.0 g/kg) were subjected to topical application at the caudal ventrolateral medullary surface (cVMS) of cocaine and two cholinomimetic pretreatment drugs. The following drug regimens were tested: 37 mM cocaine 1) given alone; 2) given 5 min after 2.7 mM carbachol pretreatment; and 3) given 5 min after 3.6 mM physostigmine pretreatment. In 7 of 11 cats, pretreatment with physostigmine decreased the incidence of cocaine-induced apneusis and hypoventilation significantly (p < 0.05); these animals showed no significant change in the mean arterial blood pressure during the 5-min pretreatment before administration of cocaine. In 4 of 11 cats, the physostigmine pretreatment produced a significant decrease in mean arterial blood pressure followed by lethal cardiorespiratory arrest when cocaine was administered. Pretreatment with carbachol resulted in cardiorespiratory responses which were not significantly different from those produced by cocaine alone. In anesthetized cats not exhibiting hypotensive responses to physostigmine, pretreatment may ameliorate cocaine-induced respiratory failure by ventral brainstem control mechanisms.

Reversal of orphenadrine-induced ventricular tachycardia with physostigmine

A 3-year-old boy developed confusion, generalized tonic-clonic seizures, and sustained ventricular tachycardia following ingestion of an unknown quantity of orphenadrine (Norflex). Although refractory to precordial thump, synchronous cardioversion, and lidocaine, the ventricular tachycardia was reversed by intravenous administration of the tertiary acetylcholinesterase inhibitor physostigmine. We discuss the underlying physiology and manifestations of anticholinergic overdose, the specific manifestations of orphenadrine overdose, and the current recommendations regarding the utilization and toxicity of physostigmine in the treatment of anticholinergic syndromes and orphenadrine intoxication.

Disinhibitory reactions to benzodiazepines: a review

This article reviews some of the important aspects of benzodiazepine-induced disinhibitory reactions. Although reactions of this type are relatively rare, they may sometimes manifest themselves in aggressive behavior accompanied by suicidal or homicidal tendencies. It appears that these reactions occur more commonly in younger patients, although the elderly (above 65 years) may also be at risk. Many mechanisms have been postulated, but none truly explain how these reactions arise. The concept that central cholinergic mechanisms may play a role, however, remains attractive and stems primarily from physostigmine's ability to successfully reverse this type of reaction. The potential role of the benzodiazepine antagonists, eg, flumazenil, in reversing disinhibitory reactions is also discussed. Apart from patients who previously exhibited poor impulse control, there are no reliable indicators for recognizing potential candidates for this type of reaction. To minimize the occurrence of disinhibitory reactions, some guidelines, which include the avoidance of certain drug combinations, the use of low doses of benzodiazepines, slow incremental intravenous administration, and good rapport with patients, are presented.

Physostigmine reversal of drug-induced paradoxical excitement

Paradoxical excitement associated with intravenous conscious-sedation in a patient undergoing dental surgery was successfully reversed with 1.0 mg physostigmine. Physostigmine is felt to have exerted this effect by 2 mechanisms: the re-establishment of homeostasis in the CNS via augmented cholinergic pathways with the net result being thalamacocortical excitation, and cholinergically-mediated increase in cerebral blood flow increasing the rate of redistribution of the intravenous sedative agents used. The most commonly encountered side-effects of physostigmine used to reverse parodoxical excitement, emergence delirium, or prolonged narcosis are bradycardia, nausea, and/or vomiting. The incidence of these side-effects is low in doses, below 2.0 mg/70 kg. body weight.

Clinical symptomatology of diphenhydramine overdose: an evaluation of 136 cases in 1982 to 1985

In West Germany, the antihistaminic diphenhydramine is marketed as a non-prescription hypnotic. Results of toxicological screening in cases of drug overdose indicate that poisoning with diphenhydramine represents a substantial part (4.5%) of the total number of intoxications. A total of 136 cases of diphenhydramine poisoning in 1982-1985 were evaluated with respect to age, ingested dose, plasma level, and clinical symptomatology. All patients had taken diphenhydramine with suicidal intent. Two-thirds of the patients were aged 14-30 years. In about 50% of the cases, between 6 and 40 times a therapeutic dose was ingested. Diphenhydramine plasma levels showed a wide range (0.1-4.7/micrograms/ml) due to differences in ingested dose and time between ingestion and admission to hospital. Impaired consciousness was the most common symptom. Psychotic behavior similar to catatonic stupor--often combined with anxiety--was highly specific for diphenhydramine poisoning. Further symptoms included hallucinations, mydriasis, tachycardia, and less frequently diplopia, respiratory insufficiency, and seizures. Primary treatment included gastric lavage, administration of activated charcoal and sodium sulfate. In one case, hemodialysis and ultrafiltration were performed which had only limited effect on diphenhydramine plasma elimination kinetics. This patient died of diphenhydramine overdose and extreme hypothermia. All intoxications except the one mentioned before had an uncomplicated clinical course. In vitro experiments indicate that diphenhydramine may be almost completely removed from the plasma compartment by hemoperfusion. Routine analysis of urine samples in diphenhydramine overdose led to the identification of 4 previously unknown metabolites and artifacts of diphenhydramine.

Diphenhydramine-induced toxic psychosis

A 24-year-old man presented to the emergency department with acute anticholinergic symptoms, hallucinations, and bizarre behavior following a large ingestion of diphenhydramine (Benadryl). Because of the large number of nonprescription preparations containing this antihistamine, similar ingestions are becoming increasingly frequent. Minor anticholinergic side effects associated with diphenhydramine are general medical knowledge. The effects of overdosage are less well known. The clinical presentation of toxic psychosis, its differential diagnosis, and its subsequent treatment are discussed.

Toxic psychosis with antihistamines reversed by physostigmine

A case of toxic psychosis due to antihistamine poisoning is described. The reversal of this state by physostigmine supports the contention that it is caused by an anticholinergic syndrome. The management of antihistamine poisoning is discussed.