The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Gary O. Martin, Ronald E. Dechert, Jessica A. Cusac, Carl F. Haas; Respiratory Care, University of Michigan, Ann Arbor, MI

BACKGROUND: Limiting VT and ventilating pressure has become critical in managing patients with ALI/ARDS. Current ARDSnet protocol suggests a VT of 6 ml/kg of predicted body weight (PBW) while limiting plateau pressure (Pplat) to 30 cmH2O. A VT up to 8 ml/kg/PBW is allowed for asynchrony provided Pplat is maintained. A concern is that without careful monitoring, pressure ventilation VT’s may be more variable and exceed recommendations. We sought to characterize our ARDS ventilation management and to determine compliance with providing initial lung protective ventilation (LPV) using volume or pressure ventilation. METHODS: A retrospective review of a ventilator management database was performed on all patients meeting AECC definition of ALI/ARDS during 2011. Data included PaO2/FiO2 at ALI/ARDS onset, age and the following on the first full day of ventilation: mode of ventilation, peak pressure (Ppeak), Pplat, VT in mL/kg PBW, PaCO2 and pH. We defined LPV as a Pplat < 30 cm H2O with a VT < 8 mL/kg PBW. To assess LPV, Pplat was used for the volume modes and Ppeak as a surrogate for Pplat in pressure modes. Each patient was classified into one of four groups based upon their initial VT:pressure (P) relationship (lowVT/low P, low VT/high P, high VT/low P, high VT/high P). The information was analyzed using SPSS software. RESULTS: 160 patients met ALI/ARDS criteria; 94 (59%) were ventilated with a volume mode and 66 (41%) with pressure. The volume group was older (53.3 vs. 46.8 yr), had a higher PaO2/FiO2 (148 vs. 112); a lower Ppeak (27.5 vs. 33.7 cm H2O), PEEP (8.9 vs. 14.9 cm H2O), PaCO2 (38 vs. 49 mmHg); and a similar VT (7.2 vs. 7.1) and pH (7.39 vs. 7.38). To assess LPV use, pressure data was missing from 1 pressure (P) and 42 volume (V) patients, leaving 117 patients (65 P, 52 V). The 52 volume patients were similar to the original 94 in all measures. The % of patients in the 4 VT/P groups are: 1) lowVT/low P: 69 vs. 17%, 2) low VT/high P: 10 vs. 60%, 3) high VT/low P: 19 vs. 11%, and 4) high VT/high P: 2 vs. 12%. LIMITATIONS: It was a retrospective review with only the initial day of ventilation assessed. CONCLUSION: More patients were ventilated with volumes and pressures aligned with a protective strategy when using volume ventilation. There appears to be a tendency to use a higher pressure during pressure ventilation, in spite of VT’s > 8 ml/kg/PBW. Further investigation as a quality improvement project is warranted. Sponsored Research - None