Patients affected by severe lung failure need a gentler form of mechanical breathing

Petrucci N, Iacovelli W

Published Online:

April 15, 2009

Critically ill patients affected by severe acute respiratory failure need air to be pumped into their lungs (mechanical ventilation) to survive. Mechanical support buys time for the lungs to heal. Nevertheless, 40 to 50% still die. Several studies suggested that mechanical breathing can also cause lung damage and bleeding. A new lung-protective way of mechanical ventilation was tested in large trials. This systematic review shows that protective ventilation can decrease death in the short term, but the effects in the long term are uncertain or unknown.

Abstract (click to read)

Background:

Patients with acute respiratory distress syndrome and acute lung injury require mechanical ventilatory support. Acute respiratory distress syndrome and acute lung injury are further complicated by ventilator-induced lung injury. Lung-protective ventilation strategies may lead to improved survival.

Objectives:

To assess the effects of ventilation with lower tidal volume on morbidity and mortality in patients aged 16 years or older affected by acute respiratory distress syndrome and acute lung injury. A secondary objective was to determine whether the comparison between low and conventional tidal volume was different if a plateau airway pressure of greater than 30 to 35 cmH20 was used.

Search strategy:

In our original review, we searched databases from inception until 2003. In this updated review, we searched The Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library 2006, Issue 3). We updated our search of MEDLINE, EMBASE, CINAHL and the Web of Science from 2003 to 2006. We also updated our search of intensive care journals and conference proceedings; databases of ongoing research, reference lists and 'grey literature' from 2003 to 2006.

Selection criteria:

We included randomized controlled trials comparing ventilation using either lower tidal volume (Vt) or low airway driving pressure (plateau pressure 30 cm H2O or less), resulting in tidal volume of 7 ml/kg or less versus ventilation that uses Vt in the range of 10 to 15 ml/kg, in adults (16 years old or older).

Data collection and analysis:

We independently assessed trial quality and extracted data. Wherever appropriate, results were pooled. We applied fixed- and random-effects models.

Main results:

We found one new study in this update for a total of six trials, involving 1297 patients, which were eligible for inclusion. Mortality at day 28 was significantly reduced by lung-protective ventilation: relative risk (RR) 0.74 (95% confidence interval (CI) 0.61 to 0.88); hospital mortality was reduced: RR 0.80 (95% CI 0.69 to 0.92); overall mortality was not significantly different if a plateau pressure less than or equal to 31 cm H2O in control group was used: RR 1.13 (95% CI 0.88 to 1.45). There was insufficient evidence about morbidity and long term outcomes.

Authors' conclusions:

Clinical heterogeneity, such as different lengths of follow up and higher plateau pressure in control arms in two trials, make the interpretation of the combined results difficult. Mortality is significantly reduced at day 28 and at the end of hospital stay. The effects on long-term mortality are unknown, although the possibility of a clinically relevant benefit cannot be excluded.

This record should be cited as:

Petrucci N, Iacovelli W. Lung protective ventilation strategy for the acute respiratory distress syndrome. Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD003844. DOI: 10.1002/14651858.CD003844.pub3

Assessed as up to date:

November 15, 2006

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Primary Review Group:

Anaesthesia Group

Health topics:

Anaesthesia & pain control > Post-anaesthetic unit/intensive care unit > Respiratory care

Anaesthesia & pain control > Ventilation in peri-anaesthetic/critical care

Lungs & airways > Ventilation in peri-anaesthetic/critical care

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Patients affected by severe lung failure need a gentler form of mechanical breathing

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