Abstract
Background:
APRV is a mode of ventilation designed to manage patients with refractory hypoxemia, particularly when other modes of ventilation fail. Despite its potential benefit, there is limited research that has evaluated the best initial settings, leading to confusion and doubts about the mode amongst practitioners. The purpose of this study was to determine if APRV is currently implemented according to established protocols.
Methods:
A retrospective chart review from patients admitted to ICUs at a 496-bed university-affiliated institution in San Antonio, between 2017 and 2019. This study was approved by the institutional IRB. The four main APRV parameters (Phigh, Plow, Thigh, Tlow) were documented and compared to current recommendations.
Results:
The mean age of the 11 patients selected for the study was 53 years (± 12.1). Most patients (63%) and were transitioned to APRV from PRV and were on APRV for an average of 30 hours (1-130). These patients had a mean PaO2 of 91.7 (± 42.5) mm Hg, FIO2 of 77.5% (± 20.9%), P/F ratio 110.2 (± 92.0), OI 26.2 (± 24.2), PIP of 27.5 cm H2O (± 9.32), PEEP of 14.2 cm H2O (± 4.9), and MAP 21.5 (± 9.0). Pplat was not recorded in the majority of patients prior to APRV. The mean values for APRV parameters obtained were P High 29.8 cm H2O (± 4.4; range 18-37), P low 3.13 cm H2O (± 1.57; range 0-15), T High: 4.11 s (± 0.72; range 3.0-5.2), and T Low: 0.59 s (± 0.18; range 0.3-1.0). Ventilator settings on APRV were maintained prior to switching back to conventional modes except mead pressures were and FIO2 were 10% lower. The oxygenation improved dramatically with a mean PaO2 of 178 and the OI decreasing almost 50% (26.2 vs 14.4). These improvements in PaO2 and OI did not reach statistical difference (P = .06 and .08, respectively). The use of the APRV mode was discontinued due to of improved oxygenation in two patients, worsening of ventilation in one patient, a worsening overall condition in one patient, and no documented reasons in the remaining seven patients.
Conclusions:
When selected, most APRV parameters were set in a similar fashion to recommended protocols. APRV was associated with improvement in oxygenation. A larger number of patients and evaluation at different institutions is necessary to evaluate how consistently suggested protocols are utilized and if a similar oxygenation response is attained.
ABG values before and while on APRV View all access options for this article.
pH
PaCO2
PaO2
HCO3-
BE
SaO2
Prior to APRV
7.30
54.3
91
26.5
-.2
90.4
While on APRV
7.37
48.7
162
28
2.5
94.8
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