A comparison of analgesic efficacy between oblique subcostal transversus abdominis plane block and intravenous morphine for laparascopic cholecystectomy. A prospective randomized controlled trial. CK Chen et al. Korean J Anesthesiol. 2013 Jun;64(6):511-516
The ultrasound-guided oblique subcostal transversus abdominis plane (OSTAP) block provides a wider area of sensory block to the anterior abdominal wall than the classical posterior approach. We compared the intra-operative analgesic efcacy of OSTAP block with conventional intravenous (IV) morphine during laparoscopic cholecystectomy.
Forty adult patients undergoing laparoscopic cholecystectomy under standard general anesthesia, were randomly assigned for either bilateral OSTAP block using 1.5 mg/kg ropivacaine on each side (n = 20) or IV morphine 0.1 mg/kg (n = 20). The intra-operative pulse rate, systolic and diastolic blood pressure and mean arterial blood pressure were monitored every fve minutes. Repetitive boluses of IV fentanyl 0.5 μg/kg were given as rescue analgesia when any of the above-mentioned parameters rose more than 15% from the baseline values. Time to extubation was documented. Additional boluses of IV morphine 0.05 mg/kg were administered in the recovery room if the recorded visual analogue score (VAS) was more than 4. Nausea and vomiting score, as well as sedation score were recorded.
The morphine group required more rescue fentanyl as compared to the OSTAP block group but the difference was not significant statistically. Time to extubation was significantly shorter in the OSTAP block group (mean [SD] 10.4 [2.60] vs 12.4 [2.54] min; P = 0.021). Both methods provided excellent analgesia and did not difer in postoperative morphine requirements. No between-group diferences in sedation score and incidence of nausea and vomiting were demonstrated.
Ultrasound-guided OSTAP block has an important role as part of balanced anesthesia. It is as efficacious as IV morphine in providing effective analgesia during laparoscopic cholecystectomy.
This was a simple concept, exploring analgesia options in day case abdominal surgery. The trial aimed to promote theatre efficiency through early extubation and faster recovery. It was also devised to reduce the rates of chronic pain from abdominal surgery.
Anaesthetists and patients were fairly randomised and all efforts made to prevent bias by blinding both patients and investigators. All patients were accounted for and the two groups similar and treated equally aside from the experimental intervention.
The sample size is relatively small. Perhaps the dose in the Morphine arm was generous for the nature of surgery. The TAP blocks were all performed by the same anaesthetist, skilled at performing the procedure. It only looked at patients undergoing laparoscopic cholecystectomy and not other abdominal surgeries. Statistically values quoted as significant, but no mention of confidence intervals.
Would it change my practice?
For routine day case lap. Cholecystectomies, probably not. I personally do not use Morphine, so it would be interesting to see a comparison with Fentanyl as primary systemic analgesia.
The time for perform the block is also operator-dependant, and surgeons patience is paramount.
Further work would be needed to assess incidence of pain at 6-months.
Summary by Dr Raj Shah