Abstract

Objectives: To compare change in lung volume (ΔV_L)using respiratory inductive plethysmography (RIP), time to recover pre-suction lung volume (t_rec) and the cardiorespiratory disturbances associated with open suction (OS) and closed suction (CS) in ventilated infants. Design: Randomised blinded cross-over trial. Setting: Neonatal intensive care unit. Patients: Thirty neonates, 20 receiving SIMV and 10 HFOV (four receiving muscle relaxant). Interventions: OS and CS were performed, in a random order, on each infant using a 6FG catheter at -19kPa for 6s and repeated after one minute. Outcome measures: ΔV_L, oxygen saturation (SpO₂) and heart rate were continuously recorded from two minutes before until five minutes after suction. Lowest values were identified during 60s after suction. Results: There were variations in all parameters during CS and OS. During SIMV no differences were found between OS and CS for maximum ΔV_L or t_rec; mean (95%CI) difference of 3.5 mL/kg (-2.8, 9.7) and 4s (-5, 13) respectively. During HFOV t_rec was longer during OS by 13s [0, 27]) but there was no difference in the maximum ΔV_L of 0.1 mV [-0.02, 0.22]). A small reduction in SpO₂ with CS in the SIMV group mean difference 6% [2.1, 9.8]) was the only significant difference in physiological measurements. Conclusions: Both OS and CS produced transient variable reductions in heart rate and SpO₂. During SIMV there was no difference between OS and CS in ΔV_L or t_rec. During HFOV there was no difference in loss of lung volume but a slightly longer time to recover after OS.