Programmed, intermittent boluses versus continuous infusion to the sciatic nerve - a non-inferiority randomized, controlled trial.

BACKGROUND: Trials comparing programmed, intermittent boluses (PIB) and continuous infusion in catheter-based nerve blocks found no analgesic differences. However, as these trials used equal doses of local anesthetic (LA), the time of action of each bolus was not accounted for. Therefore, the dose-sparing benefits of PIB may have been overlooked. We compared the analgesic effect of boluses administered in intervals resembling the time of action of each bolus with continuous infusion. We hypothesized that PIB provided non-inferior analgesia despite consuming less LA. METHODS: Eighty-one patients undergoing fore- and midfoot surgery receiving a catheter-based sciatic nerve block were randomized to ropivacaine 0.2% as PIB of 10 ml every 8th hour or as continuous infusion, 6 ml h-1 . All participants could also receive boluses of 10 ml every 4th hour as needed. A non-inferiority randomized controlled design was used. Primary outcome was pain (VAS, 0-100 mm) for 72 h using area under curve (AUC) calculation. We assumed a linear relationship between mean VAS and AUC-VAS and used a non-inferiority margin of VAS = 20 mm, corresponding to AUC-VAS = 1440 mm h. RESULTS: Mean difference in AUC-VAS was -416 mm h (95% CI -1076 to 244; p = .217) between continuous infusion (mean AUC-VAS 1206 mm h) and PIB (mean AUC-VAS 1621 mm h), establishing non-inferiority. Mean total LA consumption was significantly larger for continuous infusion compared to PIB ((468 ml (95% CI 458 to 478) vs. 136 ml (95% CI 123 to 148); p < 0.0001)). CONCLUSIONS: PIB provided non-inferior analgesia compared to continuous infusion for 72 postoperative hours despite using significantly less LA.

Surgical preparation and draping prior to induction of total intravenous anaesthesia.

INTRODUCTION: Day surgery is increasing, making efforts to improve safe and effective patient turnover of importance. We hypothesised that the introduction of a simple protocol, dictating that anaesthesia should be induced only immediately prior to surgical incision (after surgical preparations) would lead to reduced duration of anaesthesia and postanaesthesia care unit (PACU) stay. METHODS: This was a retrospective, single-centre, procedure-specific, explorative feasibility study of patients undergoing anterior cruciate ligament surgery. Timestamps were collected from the electronic patient records within a three-month period before and after introduction of the protocol at the Copenhagen University Hospital, Bispebjerg and Frederiksberg. Clinical outcomes were assessed using the PACU score, based on the modified Aldrete discharge criteria. RESULTS: A total of 44 patients were included in the after-, and 74 in the before-new-protocol group. The protocol was feasible in 44/59 patients (75%). The duration of anaesthesia was significantly reduced: 113 (± 26) versus 135 (± 32), mean difference 22 (11-33) minutes, p less-than 0.001. The duration of the PACU stay was significantly reduced: 103 (± 54) versus 80 (± 35), mean difference 23 (6-40) minutes, p = 0.01. No difference was observed in clinical outcomes. CONCLUSIONS: A simple protocol by which total intravenous anaesthesia was induced immediately prior to surgical incision was feasible, reduced the duration of anaesthesia and yielded a significant reduction in the PACU stay. Further studies with a randomised design are needed to confirm these preliminary findings. FUNDING: departmental only. TRIAL REGISTRATION: not relevant.

Response to succinylcholine in patients carrying the K-variant of the butyrylcholinesterase gene.

BACKGROUND: Succinylcholine is usually metabolized quickly by the butyrylcholinesterase enzyme (BChE) but genetic variants of BChE may prolong the duration of action. The Kalow (K) variant is the most common mutation in the butyrylcholinesterase gene (BCHE), being present in 25% of Caucasians. The significance of the K-variant for the duration of action of succinylcholine has not been well studied. Our hypothesis was that the duration of action of succinylcholine would be prolonged in patients heterozygous for the K-variant genotype compared with the normal genotype (wild-type). METHODS: We included 70 adult surgical patients who received succinylcholine 1 mg/kg for rapid sequence induction. Neuromuscular monitoring was performed using ulnar nerve stimulation and acceleromyography. Duration of action of succinylcholine was defined as the time to 90% recovery of first twitch in train-of-four (T(1) 90%), BChE activity was determined, and the presence of BCHE K and A (atypical) variants were determined using DNA analysis. RESULTS: The wild-type BCHE was present in 38 patients, and 21 were heterozygous for the K-variant. Mean (SD) T(1) 90% in patients heterozygous for the K-variant, 11.6 (3.5) minutes, was longer than in patients with the wild-type genotype, 9.5 (2.7) minutes (P = 0.023), with a mean (95% confidence interval) difference of 2.1 (0.3-4.0) minutes. Patients heterozygous for the K-variant had a BChE activity of 5978 U/L compared with 7703 U/L in the wild-type group (P = 0.0045). CONCLUSION: We conclude that the mean duration of action of succinylcholine is prolonged for the patient heterozygous for the K-variant allele by at most 4 minutes relative to the wild-type, but this difference is small relative to the wide variability and overlap in recovery times among all patients.