SESSION TITLE: Mechanical Ventilation Poster Discussion
SESSION TYPE: Original Investigation Poster Discussion
PRESENTED ON: Tuesday, October 27, 2015 at 02:45 PM - 04:15 PM
PURPOSE: Patients with ARDS are stratified using PaO2/FiO2 ratio and supported with low tidal volume mechanical ventilation. We hypothesized those patients with acute respiratory failure (ARF) supported with non-invasive ventilation (NIV) can be risk-stratified using SpO2/FiO2 ratio, and can be treated using a low tidal volume strategy for better outcomes.
METHODS: A prospective, observational study of consecutive patients requiring NIV during a nine month period. Patients were categorized depending on SpO2/FiO2 (S/F) and tidal volume to ideal body weight ratio (TV/IBW). Generalized linear models were employed to examine the association between S/F and TV/IBW with the outcomes of inpatient death, 28-day mortality, intubation, ICU admission, 30-day readmission, and hospital length of stay (LOS).
RESULTS: Among 1,957 patients using NIV, 647 patients met inclusion criteria. 54% were female, with an average age of 64 years and BMI of 34 with Charlson Comorbidity Index of 4.4 (SD=2.8). The inpatient mortality was 7%, 28- day mortality 10%, ICU admission 35%, intubation 13%, and 30-day readmission 19%, with an average LOS 7 days. The S/F groups were divided into severe <200 (14%), moderate 200-300 (54%), and mild >300 (32%). Severe hypoxia was associated with increased odds of inpatient mortality (OR=16.5, 95% CI: 4.6-59.3), intubation (OR=6.3, 95% CI: 3.0-13.3), ICU admission (OR=3.5, 95% CI: 2.0-6.1), 28 day mortality (OR=14.0, 95% CI: 4.9 40.0) and LOS (RR=1.2, 95% CI: >1.0-1.5). TV/IBW groups included those with a value within one standard deviation of the mean (6.95-11.75 ml/kg, 67%) and groups outside those values (<6.95 ml/kg, 16%; >11.75 ml/kg, 16%). A TV/IBW <6.95 ml/kg was associated with increased odds of intubation (OR=1.9, 95% CI: 1.1-3.4) and increased LOS (RR=1.3, 95% CI: 1.1-1.5). A TV/IBW >11.75 ml/kg decreased risk of prolonged LOS (RR=0.8, 95% CI: 0.7-0.9). The results of TV/IBW were independent of the effect of S/F ratio.
CONCLUSIONS: In our cohort of patients with ARF managed with NIV, patients with severe hypoxia were at highest risk for ICU admission, intubation, length of stay and mortality. TV/IBW <6.95 ml/kg was associated with higher odds of intubation and an increased risk of length of stay.
CLINICAL IMPLICATIONS: Severe hypoxia as assessed by the SpO2/FiO2 is associated with higher mortality in patients with ARF treated with NIV irrespective of the etiology. Employing higher driving pressures on NIV to generate higher TV/IBW may be beneficial but needs to be studied in a randomized clinical trial.
DISCLOSURE: The following authors have nothing to disclose: Adam Hayek, Vincent Scott, Peter Yau, Eileen Stock, Alejandro Arroliga, Shekhar Ghamande
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