Anesthesia in neuromuscular disorders. Part 1: introduction

Abstract

Disorders of skeletal muscle and peripheral nervous system are collectively called neuromuscular disorders (NMD). Important for anesthesia is that these disorders show various symptoms and have a high risk during general anesthesia. Especially administration of succinylcholine and volatile anaesthetics may cause problems. Under special circumstances opioids, nondepolarising muscle relaxants and intravenous anaesthetics can interfere with this kind of disorder, too. Complications during and after anaesthesia may result in malignant hyperthermia, malignant hyperthermia-like reactions and primary or secondary changes relating to the underlying NMD. These include cardiac and respiratory problems, dysautonomia as well as hypothermia or hyperthermia. Thus the perioperative management must be determined individually to assure the best possible safety for each patient. Preoperative examination such as ECG, echocardiography, respiratory function test including arterial blood-gas analysis, x-ray of the thorax, neurological status, and extended serum chemistry (such as CK and myoglobin) needs to be done. For premedication no drugs suppressing respiratory function should be administered. Regional anesthesia should be used whenever possible, especially in patients with respiratory and cardiac problems. The dosage of all recommended drugs should be as low as possible. Volatile anaesthetics should not be administered in the majority of NMD and succinylcholine is contraindicated, with the exception of myasthenia gravis. Additionally to the usual intraoperative monitoring, the invasive measurement of blood pressure allows frequent blood-gas analysis. It is obligate to monitor neuromuscular function and body temperature. During recovery special attention should be paid to maintain normal body temperature and electrolytes and acid-base status. The discharge of the patient from the recovery area to the normal ward should be performed only after respiratory function is normalized.