Evaluation of the effect of saline flush on the time of onset and duration of action following bolus dose of rocuronium

Abstract

Background: Circulatory factors modify the onset time of neuromuscular-blocking drugs. Therefore, we hypothesized that a bolus of saline flush immediately after rocuronium administration would shorten the onset time without influencing the duration of the rocuronium effect. Methods: A total of 84 patients were randomly allocated to either the control or saline flush group. Anesthesia was induced with propofol and fentanyl and maintained with isoflurane <1% and all patients received 0.6 mg/kg rocuronium in 10 mL of normal saline. In the saline flush group, 20 mL normal saline was immediately infused after rocuronium administration. Neuromuscular blockade was assessed using TOF-WATCH device at the adductor pollicis muscle using stimulation of ulnar nerve. The neuromuscular indices recorded were latent onset time, onset time, and clinical duration of bolus dose of rocuronium. Results: The measured latent onset time and onset time were significantly shorter within the saline flush group than the control group (P < 0.001). In addition, the clinical duration was significantly prolonged within the saline flush group (P < 0.001). Conclusion: A 20-mL saline flush administered immediately after slow intravenous 0.6 mg/kg rocuronium shortens the onset time and prolongs the clinical duration of neuromuscular blockade.