Comparison of atracurium-induced neuromuscular block in rectus abdominis and hand muscles of man.

We have compared neuromuscular block in the rectus abdominis and the hand muscles in 11 adult patients. Atracurium 0.5 mg kg-1 was administered by single bolus and anaesthesia maintained with isoflurane and nitrous oxide in oxygen. Train-of-four (TOF) stimulation was applied to the 10th intercostal space in the anterior axillary line and to the ulnar nerve at the wrist. Electromyographic (EMG) responses were recorded over the rectus abdominis and hypothenar muscles. Neuromuscular block had a significantly faster onset in the rectus abdominis (mean 1.6 (SEM 0.2) min) than in the hand (2.4 (0.3) min) (P less than 0.001). Recovery occurred more rapidly in the rectus abdominis: time to 25% TOF recovery was 39 (3) min at rectus abdominis and 51 (4) min at the hand (P less than 0.001). Time to 75% TOF recovery was 56 (4) min at rectus abdominis and 72 (6) min at the hand (P less than 0.001).

Comparison of double-burst and train-of-four stimulation to assess neuromuscular blockade in children.

Double-burst stimulation (DBS), a new technique to evaluate neuromuscular function, consists of two 50-Hz trains of 60-ms duration and 750 ms apart. DBS was compared with train-of-four (TOF) stimulation in 21 children aged 3-10 yr, during halothane anesthesia. On one arm the ulnar nerve was stimulated supramaximally with TOF stimulation every 12 s and the force of the evoked contraction of the adductor pollicis measured with an FTO3 force transducer and recorded on paper. Atracurium (0.4-0.5 mg.kg-1) was administered. During recovery from neuromuscular blockade, TOF stimulation was interrupted periodically and DBS substituted. The same stimulation patterns were applied to the ulnar nerve of the other arm simultaneously, and the clinical anesthesiologist was asked to estimate the degree of fade with both. There was good correlation between the measured TOF ratio (ratio of fourth to first response) and DBS ratio (ratio of second to first response). The TOF and DBS ratios above which fade could no longer be appreciated manually were (mean +/- SEM) 0.44 +/- 0.03 and 0.67 +/- 0.04 (P = 0.0002). Corresponding ranges were 0.3-0.8 for TOF and 0.4-0.9 for DBS, but DBS fade was always apparent if TOF fade could be detected. Therefore, in children, DBS is more sensitive than is TOF stimulation for the clinical assessment of recovery from neuromuscular blockade.

Pretreatment with non-depolarizing neuromuscular blocking agents and suxamethonium-induced increases in resting jaw tension in children.

We have studied the effect of prior administration of non-depolarizing neuromuscular blocking drugs on suxamethonium-induced increases in masseter muscle tension in 21 children aged 3-10 yr, anaesthetized with nitrous oxide and halothane using supramaximal stimulation of the ulnar nerve and the nerve to masseter. Resting tension and isometric force of contraction were measured in the adductor pollicis and masseter muscles. A sub-paralysing dose of tubocurarine 0.05 mg kg-1, a paralysing dose of atracurium 0.5 mg kg-1 or saline was given, followed 3 min later by suxamethonium 1 mg kg-1. Onset times of suxamethonium and atracurium block were shorter in the masseter than in the adductor pollicis muscle. When preceded by a sub-paralysing dose of tubocurarine, suxamethonium produced an increase in masseter tension (47 (SEM 15) g) similar to that produced by suxamethonium alone (59 (13) g). Prior administration of a paralysing dose of atracurium almost abolished this increase in tension (2.5 (2.5) g) (P less than 0.05 vs saline). The tension increase in adductor pollicis was 0, 3.2 (2.2) and 5.9 (1.1) g in the atracurium, tubocurarine and saline groups, respectively. Tubocurarine and atracurium prevented muscle fasciculations in all patients. It was concluded that increased muscle tone is a normal response to suxamethonium and is greater in the masseter than adductor pollicis. Sub-paralysing doses of non-depolarizing neuromuscular blockers have little effect, in contrast with paralysing doses. This suggests that the effect is mediated via postsynaptic receptors.

Jaw muscle tension after succinylcholine in children undergoing strabismus surgery.

The increases in tension at the masseter and adductor pollicis muscles following succinylcholine, 1 mg.kg-1, during halothane anaesthesia were measured in eight children, 3-10 yr, with strabismus. The results were compared with those obtained in a control group of general surgical patients. Supramaximal train-of-four (TOF) stimulation was applied to the ulnar nerve and the nerve to the masseter simultaneously. Jaw closure was measured by a force transducer system. In all patients, succinylcholine caused an increase in resting tone at the jaw and at the thumb. In the strabismus group, the magnitude of this increase was 55.7 +/- 23.2 g, mean +/- SD, at the jaw and 11.3 +/- 5.6 g at the thumb. This was not significantly different from the values obtained in controls, 45.3 +/- 33.4 g and 7.9 +/- 4.2 g, respectively. The duration of the phenomenon was 1-2 min in both muscles studied, and was not statistically different in the strabismus group. Time to complete neuromuscular blockade was significantly faster at the masseter, 31 +/- 6 sec--control groups; 39 +/- 11 sec--strabismus group, than at adductor pollicis, 61 +/- 34 sec--control groups; 75 +/- 28 sec--strabismus group (P less than 0.05 and 0.013 respectively). It is concluded that succinylcholine causes similar increases in jaw tension and comparable degrees of neuromuscular blockade in patients undergoing strabismus surgery as in other children.

Potency of atracurium on masseter and adductor pollicis muscles in children.

The sensitivity of the masseter to atracurium was measured in ten children aged 3-10 yr undergoing elective surgery, and compared with that of the adductor pollicis. During nitrous oxide-halothane anaesthesia and mechanical ventilation, supramaximal nerve stimulation was applied to the ulnar nerve at the elbow and to the nerve to the masseter, at a point inferior to the zygomatic arch, anterior to the mandibular condyle. Jaw closure was measured by a force displacement transducer system attached to an oral airway and connected to a metal frame fixed to the operating table 10 cm caudad to the chin. Cumulative dose-response curves for atracurium were obtained by the injection of doses followed by an infusion to compensate for elimination. The mean ED50s and ED95s were similar at the masseter and the adductor pollicis. At the masseter, these were 0.150 +/- 0.013, mean +/- SEM, mg.kg-1 and 0.254 +/- 0.021 mg.kg-1, respectively. At the adductor pollicis, corresponding values were 0.145 +/- 0.009 mg.kg-1, and 0.259 +/- 0.016 mg.kg-1. However, this relationship was not constant in every patient, and in some patients the masseter was much more sensitive than the adductor pollicis. The time from injection of the first dose of atracurium to maximum blockade was 2.5 +/- 0.2 min at the masseter and 3.2 +/- 0.2 min at the adductor pollicis (P less than 0.05). It is concluded that when atracurium is administered to paediatric patients, neuromuscular blockade is usually of the same intensity at each muscle but occurs sooner at the masseter than at the adductor pollicis.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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)

Jaw muscle tension after succinychloline in children undergoing strabismus surgery.

The increases in tension at the masseter and adductor pollicis muscles following succinylcholine, 1 mg · kg-1, during halothane anaesthesia were measured in eight children, 3-10 yr, with strabismus. The results were compared with those obtained in a control group of general surgical patients. Supramaximal train-of-four (TOF) stimulation was applied to the ulnar nerve and the nerve to the masseter simultaneously. Jaw closure was measured by a force transducer system. In all patients, succinylcholine caused an increase in resting tone at the jaw and at the thumb. In the strabismus group, the magnitude of this increase was 55.7 ±23.2 g, mean ±SD, at the jaw and 11.3 ±5.6 g at the thumb. This was not significantly different from the values obtained in controls, 45.3 ±33.4 g and 7.9 ±4.2 g, respectively. The duration of the phenomenon was 1-2 min in both muscles studied, and was not statistically different in the strabismus group. Time to complete neuromuscular blockade was significantly faster at the masseter, 31 ±6 sec -control groups; 39 ±11 sec -strabismus group, than at adductor pollicis, 61 ±34 sec -control groups; 75 ±28 sec -strabismus group (P < 0.05 and 0.013 respectively). It is concluded that succinylcholine causes similar increases in jaw tension and comparable degrees of neuromuscular blockade in patients undergoing strabismus surgery as in other children.

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

This study was performed to détérmine the effects of various doses of succinylcholine on resting tension and evoked twitch height at the masséter and adductor pollicis muscles in children. Twenty patients, aged 3-10yr, 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 masséter. 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 masséter 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 < 0.05). Onset of neuromuscular blockade was faster at the masséter, 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 masséter. With succinylcholine, 1 mg · kg-1, this increase was 51.6 ± 16.8 g at the masséter and 9.1 ± 2.3 g at the adductor pollicis. Tension returned to baseline within 1-2 min. It is concluded that in children (1) succinylcholine produces dose-related changes in resting tension; (2) this effect, although quantitatively important at the masséter, is not restricted to that muscle; and (3) relatively small doses of succinylcholine are required to block neuromuscular transmission at the jaw.

Cardiovascular responses to tracheal intubation: a comparison of direct laryngoscopy and fibreoptic intubation.

The cardiovascular responses to tracheal intubation using a fibreoptic bronchoscope or Macintosh laryngoscope were compared in twenty in-patients and twenty day-stay patients. Within these groups patients were randomly allocated to direct laryngoscopic or fibreoptic bronchoscopic intubation. Arterial blood pressure, heart rate and arterial oxygen saturation were recorded before induction and at one-minute intervals until four minutes after intubation. In both groups both laryngoscopic and bronchoscopic intubation resulted in a significant rise in blood pressure and heart rate. At no stage was there a significant difference in mean blood pressure in either group, or in heart rate in the day-stay patients, between the different methods of intubation. In the in-patients mean heart rate was significantly higher in those patients intubated with the bronchoscope at three and four minutes after intubation. Time taken for intubation was significantly longer in those patients intubated with the bronchoscope. In no patient did the arterial oxygen saturation fall below 98%.

Ischaemic pain in Buerger's disease. Report of a female patient receiving long-term local analgesia.

A female patient with Buerger's disease developed severe ischaemic pain in her left index finger which was refractory to several therapeutic measures. A silastic catheter inserted in the region of the median nerve at the elbow was topped up intermittently with local anaesthetic for 6 weeks and effected excellent analgesia. The catheter was removed when the pain had abated, and the finger tip later amputated.

The new generation gelatins. A review of their history, manufacture and properties.

Gelatin solutions of various kinds have been used as intravenous infusions since the First World War and belong to a heterogeneous group of fluids which tend to maintain the colloid osmotic pressure. They are produced by the breakdown of bovine collagen to yield solutions with a range of molecular weights. Anaphylactoid reactions are a rare but well-recognised complication of their use. The solutions help to fill a hiatus that exists between crystalloids and blood products.

Naloxone does not reverse ethanol analgesia in man.

The effects of intravenously administered ethanol and morphine on pain threshold, reaction time, motor skills and short-term memory were investigated, and the ability of naloxone to reverse any changes was studied. Morphine (loading dose 0.2 mg/kg with an infusion of 0.004 mg/kg per min) and ethanol (loading dose 0.75 ml/kg with an infusion of 0.0025 ml/kg per min) produced a similar increase in pain threshold of 6.3 (s.e.m. = 1.5, n = 8) pain units and 7.7 (s.e.m. = 1.9, n = 8) pain units, respectively. Naloxone 0.015 mg/kg produced a significant reduction in pain threshold in the morphine group, but not in the ethanol group, and there was a significant difference between the groups following naloxone (P less than 0.05, t-test, 7 d.f.). Ethanol produced a significantly greater deterioration in motor skills than did morphine (P less than 0.05, t-test, 7 d.f.) and performance in both groups was improved following naloxone (P less than 0.05, t-test, 7 d.f.). There was no significant change in the other modalities studied. It is concluded that the reversal of ethanol effects by naloxone is probably due to a non-specific analeptic action rather than blockade of opioid receptors.