Antagonisten in der Anästhesie

Zusammenfassung

Die einfache Verfügbarkeit von Antagonisten darf nicht zum sorglosen Umgang mit Agonisten verleiten. Besonders für Opiat- und Benzodiazepinantagonisten muß wegen der unter Umständen schwerwiegenden Nebenwirkungen eine saubere Indikation gestellt werden. Für die Antagonisierung der neuromuskulären Blocker kann die Indikationsstellung großzügig gefaßt werden. Die Dosis aller Antagonisten muß in Abhängigkeit von der beobachteten Wirkung titriert werden. Die Antagonisierung ersetzt nicht die Überwachung des Patienten. Im Rettungswesen ist die Gabe der Antagonisten nur ausnahmsweise sinnvoll. Hier hat die Sicherstellung der Vitalfunktionen Priorität.

Summary

In modern anaesthesia various antagonists are used. They provide efficient tools to facilitate better control of pharmacological effects and side effects of drugs routinely used in anaesthesia. Naloxone is a competitive antagonist of opioids without any intrinsic activity. It counteracts respiratory depression, pruritus, sedation and analgesia caused by opioids. It is fast-acting with a duration of action of 45 to 90 min. Several investigators have reported severe side effects of naloxone including hypertension, tachyarrhythmias, left heart failure and cardiac arrest, and hence the use of naloxone must be carefully considered in every single patient. Flumazenil is a competitive antagonist of benzodiazepines. It is a remarkably safe drug and very effective to terminate all benzodiazepine effects in anaesthesia and intensive-care patients. Serious complications caused by flumazenil have been reported in patients receiving benzodiazepines in the treatment of seizure disorders and in patients with mixed intoxications. Neostigmine is one of several antagonists of neuromuscular blocking agents. Its side effects include bradycardia, increased bronchial secretions and increased peristalsis. Indication depends on the results of neuromuscular monitoring. Physostigmine is an unspecific antagonist of the central anticholinergic syndrome, an acute psychosis that may be caused by numerous drugs used in anaesthesia. Generally, antagonists should be carefully titrated. In emergency medicine the use of these antagonists is not recommended; the primary goal is to restore vital functions.