Michel Baurain

Visual Evaluation of Residual Curarization in Anesthetized Patients Using One Hundred-hertz, Five-second Tetanic Stimulation at the Adductor Pollicis Muscle

We were looking for a clinical test to indicate a train-of-four (TOF) ratio of approximately 0.9. We compared the adductor pollicis muscle (AP) visually evaluated response to ulnar nerve 100-Hz, 5-s tetanus (RF100 Hz) with the measured AP TOF ratio in 30 ASA physical status I or II adult anesthetized (propofol, sufentanil, N2O/O2) patients. After the induction of anesthesia, the left ulnar nerve was stimulated at the wrist (single twitch and TOF) and the resultant isometric force was measured. When TOF was assessed, the independent investigators, unaware of the left AP-measured TOF ratios, visually evaluated the presence or absence of AP fading elicited by right ulnar nerve 100-Hz, 5-s tetanus. The 30 patients were randomly allocated to receive either 0.5 mg/kg atracurium (n = 15) or 0.1 mg/kg vecuronium (n = 15). The neuromuscular blockade was allowed to resolve spontaneously. A multiple logistic regression analysis was performed by computing the 771 visual observations. The probabilities of success of 100-Hz, 5-s tetanus to detect TOF ratios of 0.8, 0.85, and 0.9 were 99%, 96%, and 67%, respectively. The sensitivity and specificity of 100-Hz, 5-s tetanus as an indicator of TOF ratios of 0.85 and 0.9 are 100% and 75%, 54% and 67%, respectively. We conclude that RF100 Hz visual assessment seems to be highly sensitive in evaluating residual paralysis, as the absence of RF100 Hz visual fading at the AP is compatible with a TOF ratio >0.85. Implications: After the administration of muscle relaxants, the absence of visual fading at the adductor pollicis, elicited in anesthetized patients by 100-Hz, 5-s tetanus, is compatible with a train-of four ratio >0.85. Therefore, clinical observation of fading after 100-Hz, 5-s tetanus seems to be a highly sensitive test in evaluating residual paralysis. (Anesth Analg 1998;87:185-9)

Conditions to optimise the reversal action of neostigmine upon a vecuronium-induced neuromuscular block.

Background: Since neostigmine was introduced for reversal of neuromuscular block, there has been controversy about the optimum dose for antagonizing neuromuscular block. The purpose of this study was to characterise recovery of neuromuscular transmission following a vecuronium‐induced block 15 min after neostigmine administration using different stimulation patterns, and to determine the effects of different doses of neostigmine given at various pre‐reversal twitch heights.

Remifentanil patient-controlled analgesia effect-site target-controlled infusion compared with morphine patient-controlled analgesia for treatment of acute pain after uterine artery embolization

BACKGROUND Post-procedural pain control after uterine artery embolization (UAE) of urethral leiomyomata remains a major problem. METHODS This double-blind, randomized study tested the possibility to obtain a quicker onset of analgesia by using effect-compartment controlled remifentanil patient-controlled analgesia (remifentanil TCI-PCA) than by using i.v. morphine PCA. Both systems were connected to an i.v. catheter. Active drug or matching placebo administration was activated by a single push-button. Pain was assessed using a numerical rating scale (NRS) from 0 to 10. RESULTS NRS values were lower in the remifentanil group (with a possible difference from two to seven points on the scale) during the initial 4 h post-embolization. After the fourth hour, the NRS values were identical between the groups. No major respiratory or haemodynamic side-effect was observed. CONCLUSIONS Remifentanil PCA-TCI with a slow and progressive adapted algorithm without any associated premedication or co-medication is feasible in young healthy women undergoing UAE.

The influence of atropine dose on recovery from vecuronium-induced neuromuscular blockade

To determine whether the dose of atropine affects the rate of neostigmine-induced recovery from vecuronium-induced neuromuscular blockade, the authors monitored isometric adductor pollicis mechanical activity in 36 anesthetized (thiopental, fentanyl, nitrous oxide) adult patients (ASA physical status 1 or 2). Once surgery was completed and twitch height had spontaneously regained 25% of its initial value, the patients were randomly allocated into three groups (A10, A15, A20; n = 12 in each group) according to the dose of atropine (10, 15, or 20 micrograms/kg) that was mixed with 40 micrograms/kg neostigmine. Twitch height, train-of-four, and 50- and 100-Hz tetanic fade were recorded for 15 min after the administration of the reversal agents. No significant differences were found among the three groups in the final twitch height (95% +/- 2%), train-of-four (87% +/- 1%, 88% +/- 2%, 89% +/- 1%), and 50-Hz tetanic fade (90% +/- 1%, 94% +/- 1%, 93% +/- 1%) (mean +/- SEM). Fifteen minutes after reversal, fade in response to 100-Hz tetanus was statistically greater in the A10 group than in the two other groups (70% +/- 3% of control versus 84% +/- 4% and 81% +/- 2%) (mean +/- SEM, P less than 0.05). The present results demonstrate that larger doses of atropine facilitate neostigmines reversal of vecuronium neuromuscular blockade. The clinical implications of the differences observed in this study remain to be determined.

EVOLUTION OF VECURONIUM REQUIREMENTS FOR STABLE MECHANICAL EFFECT - COMPARISON WITH OR WITHOUT PREVIOUS SUCCINYLCHOLINE ADMINISTRATION

To evaluate possible interactions between residual succinylcholine and vecuronium, the amount of vecuronium required to maintain the twitch height (TH) at 10% of its initial value was measured over a 90-min period by the on-demand infusion method in two series of 15 adult patients (ASA class I-II). One group, the vecuronium treatment (V) group, received 70 μg-kg−1 of vecuronium and the on-demand infusion. The second group, the succinylcho-line-vecuronium treatment group (SV), was given 30 μg-kg−1 of vecuronium and on-demand infusion 5 min after the complete recovery of TH after administration of 1 mg-kg−1 of succinylcholine. During the first 10 min, the amount of vecuronium required to maintain TH at 10% of its control was significantly greater in the group given V than in the group given SV, 15122 ± 856 (mean ± SEM) vs 9851 ± 486 μg m 2-hr 1(P < 0.001). Thereafter, the amount of vecuronium required to maintain TH at 10% of control urns similar: 2808 ± 275 and 3068 ± 206 μg m 2-hr−1. When the infusion of vecuronium was stopped after 90 min, the time required for spontaneous recovery from 25 to 75% of control TH levels was similar: 20.1 ± 3.3 min in the group given V and 18.9 ±2.5 min in the group given SV (not significant). We conclude that after a vecuronium on-demand infusion of long duration (lasting more than 90 min), previous succinylcholine administration does not interfere with late vecuronium requirements and the spontaneous rate of recovery of TH.

Influence and relative sensitivities of 50-Hz and 100-Hz tetanic stimuli on subsequent tetanic fade ratios in patients receiving vecuronium.

We studied the possible effects of repetitive (1-min interval) 50- and 100-Hz tetanic stimuli on 50-Hz and 100-Hz tetanic fade ratios (RF50HZ and RF100HZ). We also evaluated the sensitivity of the recorded responses to these two tests to assess residual neuromuscular block (isometric adductor pollicis mechanical activity), either during spontaneous recovery, or 15 min after neostigmine administration, in 22 adult anesthetized (thiopental, fentanyl, N2 O/O2) patients receiving vecuronium. Two 50-Hz and two 100-Hz, 5-s duration, tetanic stimulations were randomly assessed at 1-min intervals: in a spontaneous (SPO) group (n = 11), when train-of-four (TOF) ratio spontaneously regained 0.7, and in a neostigmine (NEO) group (n = 11), 15 min after 40 micro gram/kg neostigmine was given intravenously at 25% return of control twitch tension. In the SPO group, when TOF ratio was 0.7, RF50HZ was 0.92 +/- 0.01 before and after subsequent tetanic stimulation, while RF100HZ was 0.48 +/- 0.05 and 0.47 +/- 0.05, respectively (not significant [NS]). In the NEO group, when TOF ratio was approximately 0.9, RF50HZ was 0.93 +/- 0.01 before and after subsequent tetanic stimulation, while RF100HZ was 0.80 +/- 0.02 and 0.78 +/- 0.02, respectively (NS). From patient to patient, both RF50HZ and RF100 (HZ) were also identical. In conclusion, in patients receiving vecuronium, 1) 5-s, 50- and 100-Hz tetanic stimuli may be repeated without changes at 1-min intervals and, 2) in contrast to RF50HZ, recorded RF100HZ enables one to determine residual neuromuscular block during spontaneous recovery (P < 0.001) such as after neostigmine reversal (P < 0.05). (Anesth Analg 1996;82:139-42)

Impairment of the antagonism of vecuronium‐induced paralysis and intra‐operative disopyramide administration

A 63‐year‐old male was admitted to hospital for a cholecystectomy, vagotomy and gastro‐enterostomy. Muscle paralysis was induced with 70 μg/kg vecuronium, followed by increments of 20 μg/kg when the initial twitch height returned to 2.5% of control. The patient received 3 doses of 10 mg disopyramide intravenously, on account of supraventricular ectopic beats, followed by an infusion of 2.5 mg/hour. Paralysis was reversed using 0.75 mg atropine and 2.5 mg neostigmine once the twitch height had returned spontaneously to 2.5% of its initial value. Fifteen minutes later, twitch height had returned to control value and the train‐of‐four was above 85%, but the responses to tetanic stimulation at 100 Hz and 50 Hz remained severely depressed (10% and 45%, respectively). The patients trachea was extubated after 20 minutes, but residual fade was still observed. This impairment of neuromuscular transmission, detected only with high frequency stimulation, was present with a measured concomitant plasma level of disopyramide of 5.1 μg/ml.

L'atracurium chez le sujet âgé

The effects of age on the pharmacodynamics of atracurium have been studied in twenty-four consenting adult patients undergoing elective surgery. They were divided in three groups according to their age (x±sem) : group 1 (n=8; 26±3 yr), group 2 (n=8; 53±2 yr) and group 3 (n=8; 76±2 yr). Anaesthesia was induced with methohexitone (1 mg · kg−1) and fentanyl (5 μg · kg−1), and maintained with 66 % N2O plus fentanyl on demand. Ventilation was controlled and adjusted to produce normocapnia. The isometric contraction of the adductor pollicis muscle in response to supramaximal cubital nerve stimulation delivered at 0.1 Hz was measured with a force displacement transducer. A loading dose of atracurium (0.3 mg · kg−1) was given before tracheal intubation. Thereafter, twitch height (TH) was maintained at 10 % of its baseline reading by adjusting the flow of a Harvard syringe containing 0.5 mg · ml−1 of atracurium in saline. The amount of atracurium required to maintain a stable twitch height, calculated for a 60 min period, was 14.7±1 mg · m−2 · h−1 for group 1, 13.6±1.5 mg · m−2 · BSA−1 for group 2 and 15±2.1 mg · m−2 · BSA−1 for group 3. At the end of the infusion period, the TH25–75 recovery rates were not statistically different in the three groups: 15.4±1.9 min for group 1, 14.8±1.1 min for group 2 and 14.5±1.6 min for group 3. The absence of age-related alteration of atracurium requirement and paralysis recovery rates suggested that the « physiologicaldecrease in elimination processes occuring with ageing is compensated by the auto-decomposition of the drug by the « Hofmann eliminationand/or by aspecific plasma hydrolysis. The present results underlined the interest for old patients of a molecule whose plasma elimination is not primarily dependent on renal and hepatic functions.