Dataset Information

Respiratory effects of lung recruitment maneuvers depend on the recruitment-to-inflation ratio in patients with COVID-19-related acute respiratory distress syndrome.

ABSTRACT:

Background

In the context of acute respiratory distress syndrome (ARDS), the response to lung recruitment maneuvers (LRMs) varies considerably from one patient to another and so is difficult to predict. The aim of the study was to determine whether or not the recruitment-to-inflation (R/I) ratio could differentiate between patients according to the change in lung mechanics during the LRM.

Methods

We evaluated the changes in gas exchange and respiratory mechanics induced by a stepwise LRM at a constant driving pressure of 15 cmH₂O during pressure-controlled ventilation. We assessed lung recruitability by measuring the R/I ratio. Patients were dichotomized with regard to the median R/I ratio.

Results

We included 30 patients with moderate-to-severe ARDS and a median [interquartile range] R/I ratio of 0.62 [0.42-0.83]. After the LRM, patients with high recruitability (R/I ratio ≥ 0.62) presented an improvement in the P_aO₂/F_iO₂ ratio, due to significant increase in respiratory system compliance (33 [27-42] vs. 42 [35-60] mL/cmH₂O; p < 0.001). In low recruitability patients (R/I < 0.62), the increase in P_aO₂/F_iO₂ ratio was associated with a significant decrease in pulse pressure as a surrogate of cardiac output (70 [55-85] vs. 50 [51-67] mmHg; p = 0.01) but not with a significant change in respiratory system compliance (33 [24-47] vs. 35 [25-47] mL/cmH₂O; p = 0.74).

Conclusion

After the LRM, patients with high recruitability presented a significant increase in respiratory system compliance (indicating a gain in ventilated area), while those with low recruitability presented a decrease in pulse pressure suggesting a drop in cardiac output and therefore in intrapulmonary shunt.

SUBMITTER: Zerbib Y

PROVIDER: S-EPMC8727044 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ObjectiveGlobal lung stress varies considerably with low tidal volume ventilation for acute respiratory distress syndrome. High stress despite low tidal volumes may worsen lung injury and increase risk of death. No widely available parameter exists to assess global lung stress. We aimed to determine whether the volume delivered during a recruitment maneuver (V(RM)) is inversely associated with lung stress and mortality in acute respiratory distress syndrome.DesignSubstudy of an acute respiratory distress syndrome clinical trial on esophageal pressure-guided positive end-expiratory pressure titration.SettingU.S. academic medical center.PatientsForty-two patients with acute respiratory distress syndrome in whom airflow, airway pressure, and esophageal pressure were recorded during the recruitment maneuver.InterventionsA single recruitment maneuver was performed before initiating protocol-directed ventilator management. Recruitment maneuvers consisted of a 30-second breath hold at 40 cm H2O airway pressure under heavy sedation or paralysis. V(RM) was calculated by integrating the flow-time waveform during the maneuver. End-inspiratory stress was defined as the transpulmonary (airway minus esophageal) pressure during end-inspiratory pause of a tidal breath and tidal stress as the transpulmonary pressure difference between end-inspiratory and end-expiratory pauses.Measurements and main resultsV(RM) ranged between 7.4 and 34.7 mL/kg predicted body weight. Lower V(RM) predicted high end-inspiratory and tidal lung stress (end-inspiratory: β = -0.449; 95% CI, -0.664 to -0.234; p < 0.001; tidal: β = -0.267; 95% CI, -0.423 to -0.111; p = 0.001). After adjusting for PaO2/FIO2 and either driving pressure, tidal volume, or plateau pressure and positive end-expiratory pressure, V(RM) remained independently associated with both end-inspiratory and tidal stress. In unadjusted analysis, low V(RM) predicted increased risk of death (odds ratio, 0.85; 95% CI, 0.72-1.00; p = 0.026). V(RM) remained significantly associated with mortality after adjusting for study arm (odds ratio, 0.84; 95% CI, 0.71-1.00; p = 0.022).ConclusionsLow V(RM) independently predicts high lung stress and may predict risk of death in patients with acute respiratory distress syndrome.

Project description:BackgroundRecruitment manoeuvres involve transient elevations in airway pressure applied during mechanical ventilation to open ('recruit') collapsed lung units and increase the number of alveoli participating in tidal ventilation. Recruitment manoeuvres are often used to treat patients in intensive care who have acute respiratory distress syndrome (ARDS), but the effect of this treatment on clinical outcomes has not been well established. This systematic review is an update of a Cochrane review originally published in 2009.ObjectivesOur primary objective was to determine the effects of recruitment manoeuvres on mortality in adults with acute respiratory distress syndrome.Our secondary objective was to determine, in the same population, the effects of recruitment manoeuvres on oxygenation and adverse events (e.g. rate of barotrauma).Search methodsFor this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OVID), Embase (OVID), the Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCO), Latin American and Caribbean Health Sciences (LILACS) and the International Standard Randomized Controlled Trial Number (ISRCTN) registry from inception to August 2016.Selection criteriaWe included randomized controlled trials (RCTs) of adults who were mechanically ventilated that compared recruitment manoeuvres versus standard care for patients given a diagnosis of ARDS.Data collection and analysisTwo review authors independently assessed trial quality and extracted data. We contacted study authors for additional information.Main resultsTen trials met the inclusion criteria for this review (n = 1658 participants). We found five trials to be at low risk of bias and five to be at moderate risk of bias. Six of the trials included recruitment manoeuvres as part of an open lung ventilation strategy that was different from control ventilation in aspects other than the recruitment manoeuvre (such as mode of ventilation, higher positive end-expiratory pressure (PEEP) titration and lower tidal volume or plateau pressure). Six studies reported mortality outcomes. Pooled data from five trials (1370 participants) showed a reduction in intensive care unit (ICU) mortality (risk ratio (RR) 0.83, 95% confidence interval (CI) 0.72 to 0.97, P = 0.02, low-quality evidence), pooled data from five trials (1450 participants) showed no difference in 28-day mortality (RR 0.86, 95% CI 0.74 to 1.01, P = 0.06, low-quality evidence) and pooled data from four trials (1313 participants) showed no difference in in-hospital mortality (RR 0.88, 95% CI 0.77 to 1.01, P = 0.07, low-quality evidence). Data revealed no differences in risk of barotrauma (RR 1.09, 95% CI 0.78 to 1.53, P = 0.60, seven studies, 1508 participants, moderate-quality evidence).Authors' conclusionsWe identified significant clinical heterogeneity in the 10 included trials. Results are based upon the findings of several (five) trials that included an "open lung ventilation strategy", whereby the intervention group differed from the control group in aspects other than the recruitment manoeuvre (including co-interventions such as higher PEEP, different modes of ventilation and higher plateau pressure), making interpretation of the results difficult. A ventilation strategy that included recruitment manoeuvres in participants with ARDS reduced intensive care unit mortality without increasing the risk of barotrauma but had no effect on 28-day and hospital mortality. We downgraded the quality of the evidence to low, as most of the included trials provided co-interventions as part of an open lung ventilation strategy, and this might have influenced results of the outcome.