[Residual neuromuscular blockades. Clinical consequences, frequency and avoidance strategies]

Even after administration in routine clinical dosages, muscle relaxants can lead to long-lasting residual blockades which increase the risk of severe postoperative pulmonary complications. Even without the additional effects from analgetics, sedatives or anaesthetics, a partial neuromuscular blockade, which cannot reliably be avoided either by the anaesthetist alone or by the additional use of nerve stimulators (train-of-four [TOF] ratio 0.5-0.9), can cause reductions in the vital capacity and the hypoxic breathing response, as well as obstruction of the upper airway and disruption of pharangeal function. The extent of neuromuscular recovery after an operation depends on the muscle relaxant used, the duration of administration, the anaesthetic technique and possible accompanying illnesses of the patient. It must basically be assumed that residual neuromuscular blockades are more frequent after administration of slow acting muscle relaxants such as pancuronium, than after the use of medium or rapid acting substances. If the course of a neuromuscular blockade is continually monitored during the whole anaesthetic procedure using the TOF ratio and not only occasionally at the end, a TOF ratio of 1 measured with an acceleromyograph (e.g. TOF-watch) promises an adequate neuromuscular recovery from the effects of muscle relaxants.