The development of ventilator-associated pneumonia does not change aspects of mechanical ventilation.
OBJECTIVE
To evaluate whether the development of ventilator-associated pneumonia (VAP) is associated with changes in ventilation parameters.


METHODS
Matched case-control study.


METHODS
Mixed intensive care unit of a university hospital.


METHODS
From a large database we selected 33 patients with VAP, diagnosed with quantitative cultures of bronchoscopically obtained specimens. In addition, 33 other mechanically ventilated patients who did not develop VAP were selected (controls). Patients with VAP and controls were matched on seven variables representing severity of illness: duration of ventilation until matching, diagnosis on admission, renal function, liver function, preceding infection, preceding surgery and immunosuppressive therapy. Each patient with VAP was matched to a single control. Variables regarding type and mode of ventilation and interpretation of chest radiographs were not included in the matching procedure.


RESULTS
Characteristics of mechanical ventilation (mode of ventilation, tidal volume, expired minute ventilation, peak airway pressures, mean airway pressures, level of positive end-expiratory pressure, arterial oxygen tension(PaO2)/fractional inspired oxygen (FIO2) ratio), were compared on the day of diagnosis of VAP (or matching for controls) and 2 and 4 days before. Although there was a significant difference in PaO2/FIO2 ratios between cases and controls on the day of diagnosis of VAP, the change in PaO2/FIO2 ratios during the days of study were not statistically different between patients developing VAP and controls. No significant differences were found for any of the other variables of ventilation at any of the three time points studied, nor were there significant differences in changes of these parameters within individual patients.


CONCLUSIONS
Characteristics and parameters of mechanical ventilation are not influenced by the development of VAP. It is, therefore, unlikely that these variables are useful in the diagnostic work-up of VAP.
Dennesen
P J
PJ
Department of Medical Microbiology, University Hospital Maastricht, The Netherlands. den@globalxs.nl
Van der Ven
A J
AJ
Van der Geest
S
S
Ramsay
G
G
Bonten
M J
MJ
D016022:Case-Control Studies; D006801:Humans; D009426:Netherlands / Q000453:epidemiology; D011014:Pneumonia / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods*; D015656:Respiratory Mechanics; D012307:Risk Factors; D018709:Statistics, Nonparametric