Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation.
OBJECTIVE
Although ventilation with small tidal volumes is recommended in patients with established acute lung injury, most others receive highly variable tidal volume aimed in part at normalizing arterial blood gas values. We tested the hypothesis that acute lung injury, which develops after the initiation of mechanical ventilation, is associated with known risk factors for ventilator-induced lung injury such as ventilation with large tidal volume.


METHODS
Retrospective cohort study.


METHODS
Four intensive care units in a tertiary referral center.


METHODS
Patients who received invasive mechanical ventilation for > or = 48 hrs between January and December 2001.


METHODS
None.


RESULTS
The main outcome of interest, acute lung injury, was assessed by independent review of daily digital chest radiographs and arterial blood gases. Ventilator settings, hemodynamics, and acute lung injury risk factors were extracted from the Acute Physiology and Chronic Health Evaluation III database and the patients' medical records. Of 332 patients who did not have acute lung injury from the outset, 80 patients (24%) developed acute lung injury within the first 5 days of mechanical ventilation. When expressed per predicted body weight, women were ventilated with larger tidal volume than men (mean 11.4 vs. 10.4 mL/kg predicted body weight, p <.001) and tended to develop acute lung injury more often (29% vs. 20%, p =.068). In a multivariate analysis, the main risk factors associated with the development of acute lung injury were the use of large tidal volume (odds ratio 1.3 for each mL above 6 mL/kg predicted body weight, p <.001), transfusion of blood products (odds ratio, 3.0; p < 0.001), acidemia (pH < 7.35; odds ratio, 2.0; p =.032) and a history of restrictive lung disease (odds ratio, 3.6; p =.044).


CONCLUSIONS
The association between the initial tidal volume and the development of acute lung injury suggests that ventilator-associated lung injury may be an important cause of this syndrome. Height and gender should be considered when setting up the ventilator. Strong consideration should be given to limiting large tidal volume, not only in patients with established acute lung injury but also in patients at risk for acute lung injury.
Gajic
Ognjen
O
Division of Pulmonary and Critical Care Medicine, Mayo Clinic Rochester, MN, USA.
Dara
Saqib I
SI
Mendez
Jose L
JL
Adesanya
Adebola O
AO
Festic
Emir
E
Caples
Sean M
SM
Rana
Rimki
R
St  Sauver
Jennifer L
JL
Lymp
James F
JF
Afessa
Bekele
B
Hubmayr
Rolf D
RD
D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D015999:Multivariate Analysis; D017063:Outcome Assessment, Health Care; D012044:Regression Analysis; D012121:Respiration, Artificial / Q000009:adverse effects*; D012128:Respiratory Distress Syndrome / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D012189:Retrospective Studies; D012307:Risk Factors; D013990:Tidal Volume