Persistent P Plateau Pressure Elevation Versus Sporadic: Which Is a Better Indicator of Mortality?

ABSTRACT

INTRODUCTION: ARDS net trial recommends keeping low tidal volumes (6-8 cc/IBW) and plateau pressures less than 30 cm H20. However, it is not well studied if sporadic elevation or continuous elevation of plateau pressures results in poor outcomes. We hypothesize that persistent elevation of p plat for >24 hrs. or > 6 times (measured 4 hrs. apart) continuously is associated with increased mortality. METHOD(S) Retrospective chart review of patients admitted with COVID-19 during the surge of August to September 2021 at Houston Methodist Baytown hospital. Inclusion Criteria- COVID-19 patients with respiratory failure, ards and intubated. Plateau pressures are recorded every 4 hrs. Data obtained from EPIC ICU flowsheet. Persistent elevation was defined as all the plateau pressures measured for > 24 hrs. and are continuously elevated. Exclusion criteria - patients admitted to ICU with cardiac arrest, patients who are covid negative and covid positive, but no ARDS are excluded. Tidal volume recorded is when the first highest p plateau pressure was documented. Descriptive statistics and t-tests were used to interpret the results. RESULT(S) Out of a total of 48 patients, only 12 patients survived, and 36 patients died. Mortality rate- 75%. Survivors vs. non survivors average Age(y) 42 vs.55 (p< 0.05), Tidal volume 5.98 ml/PBW vs.6.03 ml/PBW (p=0.105), Normal elastance 4.06 vs. 4.07(p=0.44), Delta P 22 vs.23(p=0.27) and ventilatory ratio 84 vs. 98(p< 0.05) were calculated during maximum plateau pressures. In patients with continuous p plat >30, 29 (85%) patients died and 5 (15%) survived. OR- 5.8 (P< 0.05). Out of the 5 patients that survived 2 went on ECMO. Intermittent p plat elevation was noted in 11 out of 14 patients who did not have continuous p plat elevation. CONCLUSION(S) Ventilatory ratio, a simple index of impaired ventilation and physiological dead space was higher in nonsurvivors compared with survivors. Continuous p plat elevation for more than 24 hrs. that is resistant to intervention might be an indirect indicator of worsening lung ventilation and increasing mortality. Rather than a single-time daily measurement of variables like delta P or p plateau pressure multiple measurements and trends might be helpful to prognosticate patients that might have poor outcomes and indicate worsening lung function.