Ventilation Practices in Subarachnoid Hemorrhage

Authors: Jonathan D Marhong Niall D Ferguson Jeffrey M Singh

Publish Date: 2014/07/15

Volume: 21, Issue: 2, Pages: 178-185

PDF Link

Abstract

Acute respiratory distress syndrome ARDS is common following aneurysmal subarachnoid hemorrhage SAH but the influence of mechanical ventilator settings on its development is unclear We sought to determine adherence to lung protective thresholds in ventilated patients with SAH and describe the association between ventilator settings and subsequent development of ARDSWe conducted a retrospective cohort study of consecutive patients receiving mechanical ventilation within 72 h of SAH at a single academic center Ventilator settings and blood gas data were collected twice daily for the first 7 days of ventilation along with ICU and hospital outcomes Lung protective ventilation was defined as follows tidal volume ≤8 mL/kg of predicted body weight positive endexpiratory pressure PEEP ≥5 cm H2O and peak or plateau pressure ≤30 cm H2O The development of ARDS was ascertained retrospectively by PaO2/FiO2 ≤300 with new bilateral lung opacities on chest Xray within one day of hypoxemiaWe identified 62 patients who underwent early mechanical ventilation following SAH PS and Continuous Positive Airway Pressure were common ventilator modes with a median tidal volume of 78 mL/kg interquartile range 68–88 median peak pressure of 14 cm H2O IQR 12–17 and median PEEP of 5 cm H2O IQR 5–6 Adherence to tidal volumes ≤8 mL/kg was seen in 64  of all observations and peak pressures 30 cm H2O were 94  of all observations All three lung protective criteria were seen in 58  of all observations Thirtyone patients 50  were determined to have ARDS ARDS patients were more frequently ventilated with a peak pressure 30 cm H2O 113  of ARDS ventilation days vs 0  of nonARDS ventilation days p  001 Initial tidal volume was not associated with subsequent development of ARDS in univariate p = 06 or multivariate analysis p = 049 Only the number of ARDS risk factors was independently associated with the development of ARDS Adjusted Odds Ratio 28 per additional risk factor 95  CI 12–65Patients with SAH requiring mechanical ventilation frequently breathe spontaneously generating tidal volumes above usual protective thresholds regardless of meeting ARDS criteria In patients with SAH the presence of an additional ARDS risk factor should prompt close screening for the development of ARDS and consideration of adjustment of ventilator settings to meet lung protective thresholds

Keywords: