Negative pressure versus loss of resistance technique for interpleural block

BACKGROUND: Loss of resistance is a commonly practiced technique among the trainees. But, for performing interpleural block (IPB), negative-pressure identification techniques have been popularized. This study was designed to evaluate the two techniques in trainee anaesthetists. METHODS: Sixty American society of anaesthesiologist (ASA) grade 1 and 2 women scheduled for elective breast surgeries under general anaesthesia were recruited for the study. The patients were randomly assigned to receive IPB (25 mL of 0.5% bupivacaine with adrenaline 5 mg/mL) with either loss of resistance technique (group LR, n=45) or the negative-pressure technique (group NP, n=45). The success rate and ease of performance was evaluated by the number of attempts and time taken. RESULTS: Higher first attempt success rate was observed in group LR (90%) when compared with group NP (80%), with a significantly shorter mean time to successful identification of interpleural space in the group LR (5 min) than in the group NP (5.8 min), P<0.01log rank test. All patients had satisfactory IPB and the median numbers of segments blocked were 7 (5–9) and 6 (5–7) in groups LR and NP, respectively. No significant complications were observed in any of the patients. CONCLUSION: Both techniques are safe and effective, but the loss of resistance technique is associated with a higher first attempt success rate performed in a shorter time by trainee anaesthetists.