Timing of Low Tidal Volume Ventilation and Intensive Care Unit Mortality in Acute Respiratory Distress Syndrome. A Prospective Cohort Study

Abstract

Rationale: Reducing tidal volume decreases mortality in acute respiratory distress syndrome (ARDS). However, the effect of the timing of low tidal volume ventilation is not well understood.Objectives: To evaluate the association of intensive care unit (ICU) mortality with initial tidal volume and with tidal volume change over time.Methods: Multivariable, time-varying Cox regression analysis of a multisite, prospective study of 482 patients with ARDS with 11,558 twice-daily tidal volume assessments (evaluated in milliliter per kilogram of predicted body weight [PBW]) and daily assessment of other mortality predictors.Measurements and Main Results: An increase of 1 ml/kg PBW in initial tidal volume was associated with a 23% increase in ICU mortality risk (adjusted hazard ratio, 1.23; 95% confidence interval [CI], 1.06-1.44; P = 0.008). Moreover, a 1 ml/kg PBW increase in subsequent tidal volumes compared with the initial tidal volume was associated with a 15% increase in mortality risk (adjusted hazard ratio, 1.15; 95% CI, 1.02-1.29; P = 0.019). Compared with a prototypical patient receiving 8 days with a tidal volume of 6 ml/kg PBW, the absolute increase in ICU mortality (95% CI) of receiving 10 and 8 ml/kg PBW, respectively, across all 8 days was 7.2% (3.0-13.0%) and 2.7% (1.2-4.6%). In scenarios with variation in tidal volume over the 8-day period, mortality was higher when a larger volume was used earlier.Conclusions: Higher tidal volumes shortly after ARDS onset were associated with a greater risk of ICU mortality compared with subsequent tidal volumes. Timely recognition of ARDS and adherence to low tidal volume ventilation is important for reducing mortality. Clinical trial registered with www.clinicaltrials.gov (NCT 00300248).

Should Early Prone Positioning Be a Standard of Care in ARDS With Refractory Hypoxemia?

“…53,54 A recent report indicated that an initial failure to recognize ARDS followed by transition to lung-protective mechanical ventilation increased mortality between 2.7 and 7.2%, depending on the size of the tidal volume used. 55 Before widespread implementation of prone positioning protocols, providers should ensure that best-practice lung-protective ventilation is being provided for their patients with ARDS.…”

Should a Portable Ventilator Be Used in All In-Hospital Transports?

“…15,16 Protective ventilation strategies incorporating the use of low tidal volumes and limiting airway pressures reduce the risk of ventilator-induced lung injury in all intubated patients at risk of injury and should be adopted as standard of care. 17 The need to transport should not excuse noncompliance to these strategies, and as demonstrated, control of pressures and volumes during manual ventilation is simply not possible even under controlled conditions.…”

“…Inappropriate tidal volumes have been identified as an independent risk factor contributing to increased mortality and length of hospital stay, 16,43 and hyperoxia, for even short periods, has been shown to worsen outcomes and increase mortality in select patient populations. 25 With hospital reimbursement tied directly to patient outcomes, minimizing risks while improving patient safety is a financial necessity.…”

Recruitment Maneuvers and PEEP Titration

“…Subsequent studies have confirmed a survival benefit for low V T ventilation. 5,6 Some studies have reported regional overdistention even with P plat Ͻ30 cm H 2 O, suggesting that there might not be a safe P plat . 7,8 Thus, the lungs should be ventilated with P plat as low as possible.…”