Ultrasound-guided perineural circumferential median nerve block with and without prior dextrose 5% hydrodissection: a prospective randomized double-blinded noninferiority trial.

BACKGROUND: Ultrasound-guided perineural peripheral nerve block using a hydrodissection technique may reduce the risk of accidental intravascular local anesthetic (LA) injection. In this prospective randomized double-blind study, we tested the hypothesis that median nerve block effectiveness is not reduced when circumferential perineural hydrodissection with dextrose 5% in water (D5W) precedes LA injection. METHODS: Patients scheduled for hand surgery were randomized to receive an ultrasound-guided median nerve block at the elbow to achieve circumferential perineural spread with either 6 mL of D5W followed by 6 mL of LA (lidocaine 1.5% with epinephrine 1:200,000) (D5W-LA group) or with 6 mL of LA alone (LA group). The primary outcome was onset time of successful anesthesia defined by a complete abolition of light touch sensation for the index finger. RESULTS: Data from 95 patients were analyzed: 43 in the D5W-LA group and 52 in the LA group. Noninferiority tests were significant (all P < 0.05) for a critical limit of 7 minutes between D5W-LA and LA groups for onset time of the primary criterion, light touch block at index finger (mean ± SD, respectively: 23.9 ± 7.4 and 22.0 ± 7.9 minutes; 95% confidence interval [CI], -5.9 to 2.1 minutes), and for cold block at index fingertip, sensory blocks at thenar eminence, and motor block. Success rate at 30 minutes (defined as complete abolition for cold and light touch at index finger) was noted in 100% and 98.1% (95% CI, -6% to 10%) and 95.2% and 96.2% (95% CI, -13% to 9%) of patients for the D5W-LA and the LA groups. CONCLUSION: Performing an ultrasound-guided perineural circumferential hydrodissection with D5W into which LA is injected leaves nerve block outcome unchanged. The assumption that this procedure may reduce the risk of intravascular injection and systemic toxicity remains to be demonstrated.

Partitioning of exhaled NO in ventilated patients undergoing cardiac surgery.

The change in exhaled NO after cardio-pulmonary bypass remains controversial. The aims were to determine whether exhaled NO sources (alveolar or bronchial) are modified after bypass, and whether mechanical ventilation (MV) settings during bypass modify exhaled NO changes. Thirty-two patients were divided into three groups: without MV during bypass and positive end-expiratory pressure (PEEP) (n=12), dead space MV without PEEP (n=10) and dead space MV with PEEP (n=10). Alveolar NO concentration and bronchial NO flux were calculated before and 1h after surgery using a two-compartment model of NO exchange developed in spontaneous breathing patients. Whereas a significant decrease in bronchial NO was found after bypass in the two groups without PEEP during bypass, this decrease was not observed in patients with dead space ventilation with PEEP. Alveolar NO was not significantly modified whatever the ventilation settings. In conclusion, the impairment of bronchial NO seemed related to airway closure since dead space mechanical ventilation with PEEP prevented its decrease.

Effects of nonsteroidal antiinflammatory drugs on patient-controlled analgesia morphine side effects: meta-analysis of randomized controlled trials.

Nonsteroidal antiinflammatory drugs (NSAIDs) are commonly combined with intravenous morphine patient-controlled analgesia to relieve postoperative pain. NSAIDs have a documented 30-50% sparing effect on morphine consumption. However, most of the studies have not demonstrated a decrease in morphine adverse effects. A meta-analysis of randomized controlled trials was performed to evaluate the risk of morphine adverse effects in patients treated with NSAIDs. Twenty-two prospective, randomized, double-blind studies including 2,307 patients were selected. NSAIDs decreased significantly postoperative nausea and vomiting by 30%, nausea alone by 12%, vomiting alone by 32% and sedation by 29%. A regression analysis yielded findings indicating that morphine consumption was positively correlated with the incidence of nausea and vomiting. Pruritus, urinary retention, and respiratory depression were not significantly decreased by NSAIDs.