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The future of driving pressure: a primary goal for mechanical ventilation?

ABSTRACT: Background:Management of patients with acute respiratory distress syndrome (ARDS) remains supportive with lung protective mechanical ventilation. In this article, we discuss the physiological concept of driving pressure, current data, ongoing trials, and future directions needed to clarify the role of driving pressure in patients with ARDS. Body:Driving pressure is the plateau airway pressure minus PEEP. It can also be expressed as the ratio of tidal volume to respiratory system compliance, indicating the decreased functional size of the lung observed in patients with ARDS (i.e., baby lung). Driving pressure as a strong predictor of mortality in patients with ARDS is supported by a post hoc analysis of previous randomized controlled trials and a subsequent meta-analysis. Importantly, the meta-analysis suggested targeting driving pressure below 13-15 cmH2O. Ongoing clinical trials of driving pressure in patients with ARDS focus mainly on physiological rather than clinical outcome but will provide important insights for the design of future clinical trials. Conclusion:Currently, no definite clinical recommendations on the routine use of driving pressure in patients with ARDS can be made, as the available data are hypothesis-generating. Randomized controlled trials are needed to evaluate the efficacy of a driving pressure-based ventilation strategy.

SUBMITTER: Aoyama H

PROVIDER: S-EPMC6172758 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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The future of driving pressure: a primary goal for mechanical ventilation?

Aoyama Hiroko H Yamada Yoshitsugu Y Fan Eddy E

Journal of intensive care 20181004

<h4>Background</h4>Management of patients with acute respiratory distress syndrome (ARDS) remains supportive with lung protective mechanical ventilation. In this article, we discuss the physiological concept of driving pressure, current data, ongoing trials, and future directions needed to clarify the role of driving pressure in patients with ARDS.<h4>Body</h4>Driving pressure is the plateau airway pressure minus PEEP. It can also be expressed as the ratio of tidal volume to respiratory system c ...[more]

PMID: 30305906

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Project description:BackgroundOutcome prediction in critically ill patients under invasive ventilation remains extremely challenging. The driving pressure (ΔP) and the mechanical power of ventilation (MP) are associated with patient-centered outcomes like mortality and duration of ventilation. The objective of this study was to assess the predictive validity for mortality of the ΔP and the MP at 24 h after start of invasive ventilation.MethodsThis is a post hoc analysis of an observational study in intensive care unit patients, restricted to critically ill patients receiving invasive ventilation for at least 24 h. The two exposures of interest were the modified ΔP and the MP at 24 h after start of invasive ventilation. The primary outcome was 90-day mortality; secondary outcomes were ICU and hospital mortality. The predictive validity was measured as incremental 90-day mortality beyond that predicted by the Acute Physiology, Age and Chronic Health Evaluation (APACHE) IV score and the Simplified Acute Physiology Score (SAPS) II.ResultsThe analysis included 839 patients with a 90-day mortality of 42%. The median modified ΔP at 24 h was 15 [interquartile range 12 to 19] cm H2O; the median MP at 24 h was 206 [interquartile range 145 to 298] 10-3 J/min/kg predicted body weight (PBW). Both parameters were associated with 90-day mortality (odds ratio (OR) for 1 cm H2O increase in the modified ΔP, 1.05 [95% confidence interval (CI) 1.03 to 1.08]; P < 0.001; OR for 100 10-3 J/min/kg PBW increase in the MP, 1.20 [95% CI 1.09 to 1.33]; P < 0.001). Area under the ROC for 90-day mortality of the modified ΔP and the MP were 0.70 [95% CI 0.66 to 0.74] and 0.69 [95% CI 0.65 to 0.73], which was neither different from that of the APACHE IV score nor that of the SAPS II.ConclusionsIn adult patients under invasive ventilation, the modified ΔP and the MP at 24 h are associated with 90 day mortality. Neither the modified ΔP nor the MP at 24 h has predictive validity beyond the APACHE IV score and the SAPS II.

Project description:BackgroundDuring passive mechanical ventilation, the driving pressure of the respiratory system is an important mediator of ventilator-induced lung injury. Monitoring of driving pressure during assisted ventilation, similar to controlled ventilation, could be a tool to identify patients at risk of ventilator-induced lung injury. The aim of this study was to describe driving pressure over time and to identify whether and when high driving pressure occurs in critically ill patients during assisted ventilation.MethodsSixty-two patients fulfilling criteria for assisted ventilation were prospectively studied. Patients were included when the treating physician selected proportional assist ventilation (PAV+), a mode that estimates respiratory system compliance. In these patients, continuous recordings of all ventilator parameters were obtained for up to 72 h. Driving pressure was calculated as tidal volume-to-respiratory system compliance ratio. The distribution of driving pressure and tidal volume values over time was examined, and periods of sustained high driving pressure (≥ 15 cmH2O) and of stable compliance were identified and analyzed.ResultsThe analysis included 3200 h of ventilation, consisting of 8.8 million samples. For most (95%) of the time, driving pressure was < 15 cmH2O and tidal volume < 11 mL/kg (of ideal body weight). In most patients, high driving pressure was observed for short periods of time (median 2.5 min). Prolonged periods of high driving pressure were observed in five patients (8%). During the 661 periods of stable compliance, high driving pressure combined with a tidal volume ≥ 8 mL/kg was observed only in 11 cases (1.6%) pertaining to four patients. High driving pressure occurred almost exclusively when respiratory system compliance was low, and compliance above 30 mL/cmH2O excluded the presence of high driving pressure with 90% sensitivity and specificity.ConclusionsIn critically ill patients fulfilling criteria for assisted ventilation, and ventilated in PAV+ mode, sustained high driving pressure occurred in a small, yet not negligible number of patients. The presence of sustained high driving pressure was not associated with high tidal volume, but occurred almost exclusively when compliance was below 30 mL/cmH2O.

Project description:Driving pressure (?Prs) across the respiratory system is suggested as the strongest predictor of hospital mortality in patients with acute respiratory distress syndrome (ARDS). We wonder whether this result is related to the range of tidal volume (VT). Therefore, we investigated ?Prs in two trials in which strict lung-protective mechanical ventilation was applied in ARDS. Our working hypothesis was that ?Prs is a risk factor for mortality just like compliance (Crs) or plateau pressure (Pplat,rs) of the respiratory system.We performed secondary analysis of data from 787 ARDS patients enrolled in two independent randomized controlled trials evaluating distinct adjunctive techniques while they were ventilated as in the low VT arm of the ARDSnet trial. For this study, we used VT, positive end-expiratory pressure (PEEP), Pplat,rs, Crs, ?Prs, and respiratory rate recorded 24 hours after randomization, and compared them between survivors and nonsurvivors at day 90. Patients were followed for 90 days after inclusion. Cox proportional hazard modeling was used for mortality at day 90. If colinearity between ?Prs, Crs, and Pplat,rs was verified, specific Cox models were used for each of them.Both trials enrolled 805 patients of whom 787 had day-1 data available, and 533 of these survived. In the univariate analysis, ?Prs averaged 13.7?±?3.7 and 12.8?±?3.7 cmH2O (P?=?0.002) in nonsurvivors and survivors, respectively. Colinearity between ?Prs, Crs and Pplat,rs, which was expected as these variables are mathematically coupled, was statistically significant. Hazard ratios from the Cox models for day-90 mortality were 1.05 (1.02-1.08) (P?=?0.005), 1.05 (1.01-1.08) (P?=?0.008) and 0.985 (0.972-0.985) (P?=?0.029) for ?Prs, Pplat,rs and Crs, respectively. PEEP and VT were not associated with death in any model.When ventilating patients with low VT, ?Prs is a risk factor for death in ARDS patients, as is Pplat,rs or Crs. As our data originated from trials from which most ARDS patients were excluded due to strict inclusion and exclusion criteria, these findings must be validated in independent observational studies in patients ventilated with a lung protective strategy.Clinicaltrials.gov NCT00299650 . Registered 6 March 2006 for the Acurasys trial. Clinicaltrials.gov NCT00527813 . Registered 10 September 2007 for the Proseva trial.

Project description:BackgroundMechanical power (MP) is the energy delivered to the respiratory system over time during mechanical ventilation. Our aim was to compare the currently available methods to calculate MP during volume- and pressure-controlled ventilation, comparing different equations with the geometric reference method, to understand whether the easier to use surrogate formulas were suitable for the everyday clinical practice. This would warrant a more widespread use of mechanical power to promote lung protection.MethodsForty respiratory failure patients, sedated and paralyzed for clinical reasons, were ventilated in volume-controlled ventilation, at two inspiratory flows (30 and 60 L/min), and pressure-controlled ventilation with a similar tidal volume. Mechanical power was computed both with the geometric method, as the area between the inspiratory limb of the airway pressure and the volume, and with two algebraic methods, a comprehensive and a surrogate formula.ResultsThe bias between the MP computed by the geometric method and by the comprehensive algebraic method during volume-controlled ventilation was respectively 0.053 (0.77, - 0.81) J/min and - 0.4 (0.70, - 1.50) J/min at low and high flows (r2 = 0.96 and 0.97, p < 0.01). The MP measured and computed by the two methods were highly correlated (r2 = 0.95 and 0.94, p < 0.01) with a bias of - 0.0074 (0.91, - 0.93) and - 1.0 (0.45, - 2.52) J/min at high-low flows. During pressure-controlled ventilation, the bias between the MP measured and the one calculated with the comprehensive and simplified methods was correlated (r2 = 0.81, 0.94, p < 0.01) with mean differences of - 0.001 (2.05, - 2.05) and - 0.81 (2.11, - 0.48) J/min.ConclusionsBoth for volume-controlled and pressure-controlled ventilation, the surrogate formulas approximate the reference method well enough to warrant their use in the everyday clinical practice. Given that these formulas require nothing more than the variables already displayed by the intensive care ventilator, a more widespread use of mechanical power should be encouraged to promote lung protection against ventilator-induced lung injury.

Project description:BackgroundSurvival of patients with acute lung injury or the acute respiratory distress syndrome (ARDS) has been improved by ventilation with small tidal volumes and the use of positive end-expiratory pressure (PEEP); however, the optimal level of PEEP has been difficult to determine. In this pilot study, we estimated transpulmonary pressure with the use of esophageal balloon catheters. We reasoned that the use of pleural-pressure measurements, despite the technical limitations to the accuracy of such measurements, would enable us to find a PEEP value that could maintain oxygenation while preventing lung injury due to repeated alveolar collapse or overdistention.MethodsWe randomly assigned patients with acute lung injury or ARDS to undergo mechanical ventilation with PEEP adjusted according to measurements of esophageal pressure (the esophageal-pressure-guided group) or according to the Acute Respiratory Distress Syndrome Network standard-of-care recommendations (the control group). The primary end point was improvement in oxygenation. The secondary end points included respiratory-system compliance and patient outcomes.ResultsThe study reached its stopping criterion and was terminated after 61 patients had been enrolled. The ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen at 72 hours was 88 mm Hg higher in the esophageal-pressure-guided group than in the control group (95% confidence interval, 78.1 to 98.3; P=0.002). This effect was persistent over the entire follow-up time (at 24, 48, and 72 hours; P=0.001 by repeated-measures analysis of variance). Respiratory-system compliance was also significantly better at 24, 48, and 72 hours in the esophageal-pressure-guided group (P=0.01 by repeated-measures analysis of variance).ConclusionsAs compared with the current standard of care, a ventilator strategy using esophageal pressures to estimate the transpulmonary pressure significantly improves oxygenation and compliance. Multicenter clinical trials are needed to determine whether this approach should be widely adopted. (ClinicalTrials.gov number, NCT00127491.)

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The future of driving pressure: a primary goal for mechanical ventilation?

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The future of driving pressure: a primary goal for mechanical ventilation?

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