Rescue Therapies in Patients with Refractory Hypoxemia

1. Rescue Therapies in Patients with Refractory Hypoxemia Moreno Franco, Pablo M.D; Rachmale, Sonal M.D; Gregory, Wilson, R. R. T; Shifang, Ding M.D.; Anas Alsara, M.D. ; Li, Guangxi M.D Mentor: Ognjen Gajic, M.D

2. Rationale • Refractory hypoxemia (RH) represents a subgroup of acute hypoxemic respiratory failure patients who have failed conventional mechanical ventilation (MV) strategies and often need rescue therapies • Rescue therapies include High Frequency Oscillation (HFO), ECMO (Extracorporeal Membrane Oxygenation), inhaled vasodilators (nitric oxide-iNO and inhaled prostacyclin- iPGI), and prone positioning

3. Hypothesis • Use of rescue therapies is associated with improved hospital mortality

4. Methods • Cohort study • Adult ICU patients requiring mechanical ventilation from 2005 to 2009 • Baseline demographics, risk factors, severity of illness and outcomes were abstracted • Multivariate logistic regression analysis used to evaluate the association between rescue therapies and hospital mortality

5. Study Subjects Selection • First identified all patients with a P/F ratio<175 on at least 2 occasions • Then we identified PEEP values within 2 hour range of first ABG with P/F ratio < 175.

6. Study Subjects Selection • After calculating 2-component LIS, those with LIS < 3 were excluded • Tidal Volume and Plateau pressures within 2 hour range of first ABG with P/F ratio<175 • After calculating 3-component LIS, those with LIS < 3 were excluded

7. Study Subjects Selection • CXR done within 24 hours of first ABG with P/F ratio < 175 were independently reviewed • Applying the University of Washington Chest Radiograph Reading Protocol, number of quadrant score was obtained (From 1-4) (http://depts.washington.edu/kclip/protocols.html)

8. All ICU Patients Age>18 years from January 1st 2005-December 31 2009 n=65,831 No research authorization n=2,184 Eligible Patients n=63,647 Mechanically Ventilated Patients P/F ratio ≤175 on at least 2 occasions * No n=60,826 Yes n=2,821 LIS Score ≥3 on at least 1 occasion Refractory Hypoxemia No n=1,995 Yes n=826 First Instance of LIS Score ≥ 3 Identified as Time Zero “Refractory Hypoxemia” *Hypoxemia Score ≥3 on 2 occasions

9. Results

10. Chart 1. Distribution of Rescue Therapies used in Patients with Refractory Hypoxemia. • 92 (11%) patients received at least one of the above rescue therapies HFO only was used in 47, prone positioning in 29, iNO in 14, iPGI in 20 and ECMO in 10 patients.

12. Table 3. Multivariate Logistic Regression Analysis for Mortality with the Use of Rescue Therapies After adjusting by APACHE III and initial oxygenation index, rescue therapy did not improve hospital mortality.

13. Conclusion • No difference in hospital mortality with use of RT in this population • RT were used in a minority of patients with RH • They were preferred for younger patients and worse hypoxemia • RT were associated with longer ICU and hospital stay

14. Special Thanks to: • Gregory, Wilson, R. R. T • Li, Guangxi M.D • Gajic, Ognjen M.D

15. Ongoing research • We have now gathered data from 2005-2010 and we are working on: • Prognostic Model for Hospital Mortality in RH • Propensity Scores for mortality with by various rescue therapies.

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