The effect of a bellows leak in an Ohmeda 7810 ventilator on room contamination, inspired oxygen, airway pressure, and tidal volume.
We investigated the effect of a small bellows leak (bellows full at end-expiration) on inspired oxygen fraction (Fio(2)), exhaled tidal volume (Vt), airway pressure, and room contamination in an oxygen-driven anesthesia ventilator (Ohmeda 7810, Madison, WI). CO(2) concentration at the ventilator exhalation valve, Fio(2), Vt, and airway pressure were measured (n = 3) while ventilating a CO(2)-producing test lung at 8 breaths/min and an inspiratory/expiratory ratio of 1:2, with and without a bellows leak (4-mm-long tear). Set Vt was 400, 600, 800, and 1000 mL. Fresh gas flow (FGF) was 0.3 L/min O(2) and (a) 5.0 L/min air, (b) 2.0 L/min air, and (c) 0.2 L/min nitrogen. There was no clinical difference in Fio(2), Vt, PIP (peak inspiratory pressure) and PEEP (positive end-expiratory pressure), with and without a 4-mm bellows tear, at all FGFs and Vt settings. CO(2) at the ventilator exhalation valve was always nonzero with a bellows leak, indicating that CO(2)-laden circuit gas was contaminating the drive gas via the bellows leak. A 4-mm bellows tear in an Ohmeda 7810 ventilator allows anesthetic gases to contaminate ambient air but does not cause clinically significant changes in Fio(2), exhaled Vt, PIP, or PEEP.
Lampotang
Samsun
S
Department of Anesthesiology, University of Florida, Gainesville, FL, USA. slampotang@anest.ufl.edu
Sanchez
Justin C
JC
Chen
Baixi
B
Gravenstein
Nikolaus
N
D000399:Air Pressure; D002245:Carbon Dioxide / Q000032:analysis; D003627:Data Interpretation, Statistical; D004866:Equipment Contamination; D004868:Equipment Failure; D010100:Oxygen / Q000032:analysis*; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology*; D013990:Tidal Volume / Q000502:physiology*; D012122:Ventilators, Mechanical
D002245:Carbon Dioxide; D010100:Oxygen