The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

INITIAL NPPV SETTINGS MAY BE A USEFUL PREDICTOR OF OUTCOMES.

Carol T. Spada1, Paul F. Nuccio1, Gerald L. Weinhouse2, Rikesh Gandhi3, Po-Shun Lee2



Introduction: Noninvasive Positive Pressure Ventilation (NPPV) has been a valuable modality in the management of patients with acute respiratory failure. Multiple studies have shown it to be a preferred treatment option for patients with chronic obstructive pulmonary disease (COPD); however, the utility of NPPV for other causes of hypoxemic respiratory failure is less clear. Many variables may impact outcomes of patients receiving NPPV. We therefore conducted a prospective observational study on patients with acute respiratory failure managed by NPPV.

Methods: Patients receiving NPPV (BiPAP Vision System, Respironics) admitted to the medical intensive care units (ICU) at the Brigham & Women's Hospital are identified and recruited for this prospective observational study. Each patient's height is recorded as per standard protocol and is used to calculate predicted body weight (PBW). Respiratory mechanics and NPPV settings are recorded every 4 hours until the discontinuation of NPPV for up to 24 hours. Tidal Volume (VT) delivered is expressed as ml/PBW kg. Outcomes analyzed include clinical improvement post NPPV, and worsening respiratory status as reflected by oxygen saturation/FiO2 (S/F). Interim analysis carried out for the first 83 patients are presented here. Mann-Whiney U test was used to compare two variables.

Results: Of the 83 patients included, there were 40 males and 43 females, with an average age of 59. Preliminary findings showed that certain parameters may have a predictive value for discriminating patients with clinical improvement managed by NPPV. In our study, those parameters included FiO2, IPAP, and minute ventilation (MV). Compared to those who did not improve with NPPV, patients with clinical improvement have significantly lower initial mean FiO2 (0.58 vs. 0.7, p=0.02), and tend to have lower initial mean IPAP (11.5cm H2O vs. 13.1cm H2O, p=0.06) and MV (12.6 L vs. 15.4 L, p=0.1).

Conclusion: Critically ill patients who require more ventilatory assistance may not respond to NPPV support. Based on our results, recommendations could be made to consider early intubation for those patients who have higher oxygenation and/or ventilation requirements. Further study is warranted in this area.