Dose-related effects of succinylcholine on the adductor pollicis and masséter muscles in children

Abstract

This study was performed to determine the effects of various doses of succinylcholine on resting tension and evoked twitch height at the masseter and adductor pollicis muscles in children. Twenty patients, aged 3-10 yr, ASA physical status I or II, were randomly assigned to receive succinylcholine 0.15, 0.25, 0.50 or 1.00 mg.kg-1, during halothane-nitrous oxide anaesthesia. Supramaximal train-of-four stimulation was applied simultaneously to the ulnar nerve and the nerve to the masseter. Transducers recorded force at the jaw and the thumb. Maximum blockade of the first twitch (T1) and maximum resting tension change were measured. Potency of succinylcholine at the two muscles was estimated by linear regression of the logit transformation of T1 versus log dose. The relationship between resting tension change and log dose was established by linear regression. The masseter muscle was more sensitive to succinylcholine than the adductor pollicis with an ED95 of 0.28 +/- 0.02 (mean +/- SEM) vs 0.44 +/- 0.05 mg.kg-1 (P less than 0.05). Onset of neuromuscular blockade was faster at the masseter, and recovery occurred simultaneously in both muscles. A dose-related increase in resting tension was observed in both muscles, but its magnitude was five times greater at the masseter. With succinylcholine, 1 mg.kg-1, this increase was 51.6 +/- 16.8 g at the masseter and 9.1 +/- 2.3 g at the adductor pollicis. Tension returned to baseline within 1-2 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adverse Effects of Depolarising Neuromuscular Blocking Agents

“…Measurements were made after the establishment of peripheral neuromuscular blockade. This response as a variation of normal has been confirmed by other authors (Plumley et al 1990). This has also been demonstrated in children anaesthetised with enflurane (VanDerSpek et al 1988) and isoflurane ( Van-DerSpek et al 1990).…”

Variants of malignant hyperthermia. Special problems for the paediatric anaesthesiologist

“…Leary & Ellis (1990) measured the 'resistance' of the masseter muscles following various doses of suc-cinylcholine in adult patients using a unique myotonometer and also found a 'myotonic' response in the majority of patients. Plumley et al (1990) using a different transducer measured masseter muscle tension and also found that succinylcholine produces a dose-related increase in resting tension. The increase in resting tension appears to be a normal physiological action of succinylcholine.…”

The place of suxamethonium in pediatric anesthesia

“…Often, this increase in tension is not noticed. But it has been shown to be dose related (41). In extreme cases, it is impossible to intubate the trachea because the mouth cannot be easily opened after i.v.…”