[Ultrasound control of local anaesthetic location after TAP block performed using landmark-based technique: a cohort study]. / Contrôle échographique du site d'injection lors de la réalisation d'un TAP bloc à l'aveugle : une étude ouverte de cohorte.

OBJECTIVE: TAP is a regional anaesthetic technique where local anaesthesic (LA) is injected between the internal oblique and the transversus abdominis muscles in order to block intercostal nerves. The technique originally described, is based on the identification of the lumbar triangle of Petit as the area where to insert the needle before the LA injection. We performed a study to determine, using ultrasonography, the actual location of the LA when TAP block was performed using landmark-based technique. STUDY DESIGN: Prospective and observational study. METHODS: Fifty-two patients scheduled for ileostomy closure surgery under general anaesthesia received a TAP block (20 mL 0.75% ropivacaine) based on standard anatomical landmarks technique. Ultrasonography was used immediately after the block to determine the LA placement. Failed blocks were considered when the patient required intravenous morphine in the immediate postoperative period for pain localised at the operative site. RESULTS: LA solution was injected in the right place in 14 cases out of 52. Only one of these patient received morphine in the postoperative period. In the remaining 38 blocks, the LA was administered in adjacent anatomical structures and 25 failed. Two injections in the peritoneum were observed. CONCLUSION: The localization of LA after the TAP block being performed by landmark-based techniques is highly variable. In the majority of patients, the LA was injected in adjacent anatomical structures with unpredictable block results. This may promote the use of ultrasound-guided technique to perform the TAP block.

Duration of the pharmacodynamic interaction between pancuronium and mivacurium.

The aim of this study was to determine for how long the duration of action of increments of mivacurium can be influenced by previous pancuronium administration. Fifteen patients, ASA I or II, undergoing general anaesthesia for major abdominal surgery were investigated. The post-tetanic count (PTC) was measured at the adductor pollicis muscle. Pancuronium 0.1 mg kg-1 was injected first. At recovery of the 10th response of the PTC (PTC10), a second dose of pancuronium was injected (0.02 mg kg-1). On recovery to PTC10, a bolus of mivacurium (0.04 mg kg-1) was given and regularly repeated at recovery of PTC10 until the end of surgery. The mean duration of the second dose of pancuronium was 53 min (SD 13 min) and of the first dose of mivacurium, 66 min (SD 14 min) (P < 0.01). The duration of action of further mivacurium boluses decreased significantly until the fifth dose. It took 222 minutes (95% confidence interval 190, 253 min) after the second pancuronium dose before the duration of action of mivacurium returned to normal values and became constant and predictable.