Neuromuscular Blockade Monitoring

Monitoring neuromuscular blockade involves two steps: stimulation of a motor nerve and assessment of the muscular response. In theatre, medical personnel mainly use visual and tactile assessment of the degree of neuromuscular blockade because of the relative convenience of this method. Several different patterns of stimulation, such as single twitch and train of four (TOF), have been developed to try to improve the sensitivity of monitoring. Tetanic stimulation is applied before the tetanic count. It is used to assess when there is profound block such that there are no twitches on TOF. Neuromuscular blocking drugs (NMBDs) cause paralysis of all voluntary muscles in the body, but some are more sensitive than others. Commonly monitored nerves in theatre are: facial nerve, ulnar nerve and posterior tibial nerve. In order of decreasing sensitivity: eyes, facial muscles, neck, extremities, limbs, abdominal, muscles, glottis, and intercostal muscles.