The effects of age on maintenance of intense neuromuscular block with rocuronium

BACKGROUND

Increasing age is associated with a longer duration of action of neuromuscular block. The aim of this study was to determine the influence of ageing on the recovery of the post-tetanic count (PTC) from rocuronium-induced neuromuscular block.

METHODS

Twenty-two younger (20-60 years) and 22 older (> 70 years) patients were enrolled in this study. After induction of anaesthesia with fentanyl and propofol, all patients initially received 1 mg/kg rocuronium and neuromuscular block were evaluated by contractions of the adductor pollicis muscle to ulnar nerve train-of-four stimulation using an acceleromyograph. Subsequently, intense rocuronium-induced block was determined every 6 min using the PTC during 1.0-1.5% sevoflurane and remifentanil anaesthesia. When the first response to the PTC stimulus was detected, 0.2 mg/kg rocuronium was additionally administered, and again, spontaneous recovery of neuromuscular function was monitored until the first response to the PTC reappeared.

RESULTS

Median values (range) of the times from the administration of 1 mg/kg and 0.2 mg/kg rocuronium until recovery of the first detectable PTC were significantly longer in the older [51.0 (27-100) min, P < 0.0001 and 30.0 (12-66) min, P = 0.0036, respectively] than the younger patients [31.5 (21-45) min and 18.0 (12-36) min, respectively].

CONCLUSION

The times from rocuronium injection to reappearance of the first response to PTC stimulation are approximately twofold longer and more variable in older than younger patients. Hence, the dosing interval of rocuronium should be adjusted using neuromuscular monitoring when maintaining intense neuromuscular block, especially in older patients.

Correlation between cardiac output and reversibility of rocuronium-induced moderate neuromuscular block with sugammadex

BACKGROUND

The aim of this study was to evaluate the correlation between cardiac output (CO) and reversibility of rocuronium-induced moderate neuromuscular block with sugammadex in elderly patients.

METHODS

Fifty elderly (≥ 65 years) patients were enrolled in this study. During 1.0-1.5% end-tidal sevoflurane and remifentanil anaesthesia, contraction of the adductor pollicis muscle in response to ulnar nerve stimulation was acceleromyographically quantified. All patients initially received 1 mg/kg rocuronium followed by 0.2 mg/kg whenever the second twitch T2 of the train-of-four (TOF) response reappeared. CO was measured throughout the study using a FloTrac™/Vigileo™ monitor. After completion of surgery and at the reappearance of T2, the time required for a bolus dose of 2 mg/kg sugammadex to facilitate recovery to a TOF ratio of 0.9 was recorded, and its correlation with CO was analysed.

RESULTS

Adequate recovery of neuromuscular block was achieved after sugammadex in all patients. Mean CO at the time of reversal with sugammadex was 5.3 l/min (1.3), and recovery time to a TOF ratio of 0.9 was 173.4 s (54.8). A statistically significant inverse correlation was seen between the time to recovery to a TOF ratio of 0.9 and CO [reversal time (s) = -27.7·CO + 298.7, R(2)  = 0.461, P < 0.0001].

CONCLUSIONS

The time to reach a TOF ratio of 0.9 following sugammadex is dependent on CO in elderly patients.

Influence of smoking and CYP2C19 genotypes on H. pylori eradication success

CYP2C19 polymorphisms and smoking influence the efficacy of H. pylori eradication therapy, but interaction between the two have hitherto not been examined. A total of 142 H. pylori-positive patients who received triple drug therapy with lansoprazole, amoxicillin and clarithromycin were categorized into three groups with regard to diplotypes of CYP2C19: homozygous extensive metabolizer (homEM), heterozygous EM (hetEM), and poor metabolizer (PM). The overall success rate was 61.3%. Smoking was an independent risk factor of eradication failure (OR 2.81, 95% CI 1.14-6.91), whereas CYP2C19 polymorphisms were less influential. Among non-smokers, the homEM and hetEM groups showed worse eradication rates (58.5 and 67.3%) relative to PM (76.2%) as expected; however, an opposite trend was observed among smokers (homEM 50.0%, hetEM 46.7%, PM 20.0%), indicating possible interactions with CYP2C19 polymorphisms. Smoking has a greater influence on H. pylori eradication than the CYP2C19 genotype. Interaction between smoking and CYP2C19 should be examined in the future.

Effect of histamine on adrenal 17-hydroxycorticoid secretion in unanesthetized dogs

Dogs with previously sectioned dorsal spinal roots (T11-L3) were used in experiments for collecting the adrenal venous blood without anesthetizing or evoking any pain. Intravenous injection of histamine in doses of 0.05–1.0 mg/kg body wt. was demonstrated to produce a marked acceleration of 17-hydroxycorticoid secretion. The time courses of changes in the secretion rate after injection of varying doses of histamine are compared.

Effect of ether anesthesia on 17-hydroxy-corticosteroid secretion in dogs

In dogs with previously cut dorsal spinal roots (T11-L3), adrenal venous blood was collected without anesthetic or pain. Ether was then inhaled for 30–60 minutes. During and after ether inhalation, adrenal venous blood was again collected and the plasma was analyzed for 17-hydroxycorticosteroids (17-OHCS). The mean preinhalation control secretion rate of 17-OHCS by one adrenal was 0.10 (0.06–0.20) µg/kg/min. During ether inhalation it increased to 0.34–1.2 µg/kg/min. Thirty to sixty minutes after the end of ether inhalation the secretion rate increased to a maximum of 0.79–1.8 µg/kg/min. and then decreased.

SEPARATION BY ETHANOL OF COMMON AND SOMATIC ANTIGENS OF ENTEROBACTERIACEAE

Suzuki, T. (Children's Hospital, Buffalo, N.Y.), E. A. Gorzynski, and E. Neter. Separation by ethanol of common and somatic antigens of Enterobacteriaceae. J. Bacteriol. 88:1240-1243. 1964.-Ethanol in a concentration of 85% permits separation from crude culture supernatant fluids of the common enterobacterial antigen and the O antigen, the former being ethanol-soluble, the latter being ethanol-insoluble. The evidence was obtained in hemagglutination, hemolysis, and hemagglutination-inhibition tests. In contrast to the crude antigens obtained from enteric bacteria other than Escherichia coli O14, the ethanol-soluble fraction is immunogenic in the rabbit upon intravenous injection, and antibodies against the common antigen are produced in relatively high titers. Aqueous mixtures of ethanol-soluble and -insoluble fractions engender antibodies against the common antigen in titers significantly lower than those stimulated by the soluble fraction alone. Ethanol-treated whole antigen fails to stimulate antibody formation against this antigen. These results suggest the presence of an inhibitor in the ethanol-insoluble fraction.