Analgesic interaction between ondansetron and acetaminophen after tonsillectomy in children: the Paratron randomized, controlled trial.

BACKGROUND: The mechanism of action of acetaminophen remains unclear. One hypothesis involves an interaction with the serotoninergic system. Antagonists to serotonin (5-HT)3 receptors (setrons) have antiemetic properties. Therefore, co-administration of acetaminophen and a setron could lead to a decrease or a loss of acetaminophen analgesic effects. The aim of this study was to demonstrate such an interaction. METHODS: Paratron is a prospective, randomized, controlled, double-blind, parallel group trial. All children aged 2-7 years (n = 69) scheduled for a tonsillectomy ± adenoidectomy received intraoperative acetaminophen with ondansetron or droperidol. Pain scores [Children's Hospital of Eastern Ontario Pain Scale (CHEOPS)], morphine consumption and the incidence of post-operative nausea and vomiting (PONV) were measured for 24 h following surgery. RESULTS: Pain scores were not different at all times between the groups but median morphine consumption (µg) in recovery was 322.5 [interquartile range (IQR) 0.0-500.0] and 0 (IQR 0-0) in the ondansetron (n = 35) and droperidol (n = 34) groups, respectively (p = 0.004). The percentages of patients who received morphine titration were 57.1% and 20.6% in the ondansetron and droperidol groups, respectively (p = 0.008). No significant difference was found for PONV. CONCLUSIONS: An interaction between acetaminophen and ondansetron is suggested, with children receiving three times more morphine during pain titration in the recovery room. More studies are necessary to evaluate whether this finding is clinically relevant enough to preclude the simultaneous perioperative administration of both drugs in the future.

[Use of isoflurane in a closed-circuit. Economic advantages]. / Utilisation de l'isoflurane en circuit fermé. Avantages économiques.

The present study was designed to assess whether isoflurane requirement was significantly affected by fresh gas flow in a closed-circuit system. Sixty patients scheduled for orthopaedic procedures were randomly assigned into three groups. In group A (n = 20), anaesthesia was conducted with a fresh gas flow of 482.5 +/- 186.6 ml X min-1, corresponding to the patient's metabolic demand. In group B (n = 20), the fresh gas flow was 2000 ml X min-1. In group C (n = 20), it was adjusted to the ventilation minute, i.e. 7145 +/- 986 ml X min-1. Artificial ventilation was conducted using a tidal volume of 10 ml X kg-1 and a rate of 10 to 12 c X min-1. Anaesthesia was induced after 10 min denitrogenation with fentanyl (4 micrograms X kg-1), thiopentone (4 mg X kg-1) and vecuronium (0.1 mg X kg-1). FIO2 was then brought to 0.5 in nitrous oxide and was monitored continuously using a polarographic oxymeter. Liquid isoflurane was injected in the expiratory limb of the circuit using an electrical syringe driver. Alveolar concentration of isoflurane was set at 0.92 vol. % according to Lowe and Ernst. Statistical analysis was carried out using Student's test for means. Anaesthesia lasted 138 +/- 88.3 min in group A, 125.5 +/- 45.1 min in group B and 146.5 +/- 50 min in group C, no difference being significant.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prolonged brachial plexus block with bupivacaine]. / Bloc prolongé du plexus brachial à la bupivacaïne.

A prolonged brachial plexus block with bupivacaine hydrochloride is described. Anaesthesia was induced with 40 ml of a solution made of equal parts of 0.50% bupivacaine hydrochloride and distilled water. Reversal of the motor block began 24 h later. Total recovery was observed 30 h after the onset of anaesthesia. Neurotoxicity of bupivacaine hydrochloride was known to be weak and could not explain the increased length of the block. The dilution of 0.50% bupivacaine hydrochloride resulted in a very low osmolality (141 mosm X kg-1 vs 242 mosm X kg-1 for 0.25% bupivacaine hydrochloride commercial solution). Whether this low osmolality caused nerve lesions was unknown. Postoperative exploration revealed a bilateral slowing down of conduction in the brachial plexus of this 73 year old patient. The importance of this finding could not be assessed.