Therapy Lung open ventilation study group - Ventilation Strategy Using Low Tidal Volumes, Recruitment Maneuvers, and High Positive End-Expiratory Pressure for Acute Lung Injury and Acute Respiratory Distress Syndrome: A Randomized Controlled Trial
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Summary
Posted By:	AMIT KANSAL
E-Mail:	akan95@gmail.com
Posted Date:	06/09/08
Title:	Lung open ventilation study group - Ventilation Strategy Using Low Tidal Volumes, Recruitment Maneuvers, and High Positive End-Expiratory Pressure for Acute Lung Injury and Acute Respiratory Distress Syndrome: A Randomized Controlled Trial
Authors:	Meade et alJAMA. 2008 Meade MO, Cook DJ, Guyatt GH, Slutsky AS, Arabi YM, Cooper DJ, Davies AR, Hand LE, Zhou Q, Thabane L, Austin P, Lapinsky S, Baxter A, Russell J, Skrobik Y, Ronco JJ, Stewart TE; Lung Open Ventilation Study Investigators.
Reference:	JAMA. 2008 Feb 13;299(6):637-45.
Link:	Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract:	Context: Low-tidal-volume ventilation reduces mortality in critically ill patients with acute lung injury and acute respiratory distress syndrome. Instituting additional strategies to open collapsed lung tissue may further reduce mortality. Objective: To compare an established low-tidal-volume ventilation strategy with an experimental strategy based on the original “open-lung approach,” combining low tidal volume, lung recruitment maneuvers, and high positive-end–expiratory pressure. Design and Setting: Randomized controlled trial with concealed allocation and blinded data analysis conducted between August 2000 and March 2006 in 30 intensive care units in Canada, Australia, and Saudi Arabia. Patients: Nine hundred eighty-three consecutive patients with acute lung injury and a ratio of arterial oxygen tension to inspired oxygen fraction not exceeding 250. Interventions: The control strategy included target tidal volumes of 6 mL/kg of predicted body weight, plateau airway pressures not exceeding 30 cm H2O, and conventional levels of positive end-expiratory pressure (n = 508). The experimental strategy included target tidal volumes of 6 mL/kg of predicted body weight, plateau pressures not exceeding 40 cm H2O, recruitment maneuvers, and higher positive end-expiratory pressures (n = 475). Main Outcome Measure: All-cause hospital mortality. Results: Eighty-five percent of the 983 study patients met criteria for acute respiratory distress syndrome at enrollment. Tidal volumes remained similar in the 2 groups, and mean positive end-expiratory pressures were 14.6 (SD, 3.4) cm H2O in the experimental group vs 9.8 (SD, 2.7) cm H2O among controls during the first 72 hours (P < .001). All-cause hospital mortality rates were 36.4% and 40.4%, respectively (relative risk [RR], 0.90; 95% confidence interval [CI], 0.77–1.05; P = .19). Barotrauma rates were 11.2% and 9.1% (RR, 1.21; 95% CI, 0.83–1.75; P = .33). The experimental group had lower rates of refractory hypoxemia (4.6% vs 10.2%; RR, 0.54; 95% CI, 0.34–0.86; P = .01), death with refractory hypoxemia (4.2% vs 8.9%; RR, 0.56; 95% CI, 0.34–0.93; P = .03), and previously defined eligible use of rescue therapies (5.1% vs 9.3%; RR, 0.61; 95% CI, 0.38–0.99; P = .045). Conclusions: For patients with acute lung injury and acute respiratory distress syndrome, a multifaceted protocolized ventilation strategy designed to recruit and open the lung resulted in no significant difference in all-cause hospital mortality or barotrauma compared with an established low-tidal-volume protocolized ventilation strategy. This “open-lung” strategy did appear to improve secondary end points related to hypoxemia and use of rescue therapies.
Are the Results Valid?
1. Was the assignment of patients to treatments randomized? ( Was allocation concealment maintained?)
	Yes, allocation concealment was maintained by use of a central computerized telephone system. Randomization was stratified by site and used permuted blocks of variable size.
2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?
2a. Was followup complete?
	Yes. Only two patients (one from each arm) were excluded from the ITT analysis. Both due to withdrawal of consent.
2b. Were patients analyzed in the groups to which they were randomized?
	Yes.
3. Were patients, health workers, and study personnel blind to treatment?
	Data analysts conducted the primary analysis blinded to treatment group.
4. Were the groups similar at the start of the trial?
	Yes. Table 3 demonstrates good balance.
5. Aside from the experimental intervention, were the groups treated equally?
	Table 5 demonstrates similar co-interventions in both arms.
What are the Results?
1. How large was the treatment effect?
	No significant difference in all-cause hospital mortality (36 % vs 40%, RR 0.90 0.90; 95% confidence interval [CI], 0.77-1.05; P = .19). No significant difference in rates of barotrauma & duration of mechanical ventilation. Improved secondary end points related to lower rates of refractory hypoxemia in the experimental group (4.6% vs 10.2%; RR, 0.54; 95% CI, 0.34-0.86; P = .01), reduced death with refractory hypoxemia (4.2% vs 8.9%; RR, 0.56; 95% CI, 0.34-0.93; P = .03), and previously defined lower eligible use of rescue therapies (5.1% vs 9.3%; RR, 0.61; 95% CI, 0.38-0.99; P = .045). A subgroup analysis was conducted to investigate interaction between severity of disease (defined by quartiles of PaO2/fiO2) & treatment effect - No interaction was found.
2. How precise was the estimate of the treatment effect?
	Reported above.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care?
	Yes. Standard ICU patients with ALI (85% were ARDS) due to direct as well as indirect injuries. Excluded severe chronic lung diseases.
2. Were all clinically important outcomes considered?
	YES. Barotrauma/ duration of mechanical ventilation - no difference. 22% Patients recieving recruitment maneuver had adverse events, pg 643(81 patients out of 366 recieving recruitment maneuver - total 475 patients in that group). Patients in experimental strategy recieved more iv fluids, probably more hemodynamic instability.
3. Are the likely treatment benefits worth the potential harms and costs?
	This very well conducted trial(still underpowered -- not a definitive –ve trial) shows improved surrogate end-points with use of Open lung ventilation without mortality benefit and with increased risk of adverse events. This approach to ventilation could be reserved for refractory ARDS patients only (when I am looking towards rescue therapies!), after optimising the fluid status and be very watchful of cardiovascular and hypoxic adverse events. This approach should not be used without adequate expertise.
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