Does the use of large ventilator tidal volume increase the incidence of postoperative complications?

The use of large tidal volumes (LTV) (10–15 ml/kg) for mechanical ventilation (MV) of patients with ARDS has been shown to be detrimental. Whether or not the use of LTV for postoperative mechanical ventilation increases the risk of pulmonary complications, pneumonia, and consequent mortality from pulmonary causes is unknown. We performed this study with the hypothesis that postoperative patients receiving MV with large tidal volume would have an increased incidence of pulmonary complications and mortality. Postoperative abdominal and thoracic surgical patients receiving either 9 ml/kg or 14 ml/kg tidal volumes for mechanical ventilation were studied. Those with pre-existing atelectasis, pneumonia or ARDS were excluded. The patients were managed in the SICU and were weaned and extubated according to standard practice. Extubated patients who later required reintubation were not placed on study tidal volumes. Data collection included patient demographics, surgical diagnoses, operations, preoperative chest X-ray results, the size of tidal volume, duration of MV, incidence of pulmonary complications, and patient outcome. The data was analyzed using SPSS statistical soft ware. One hundred and two patients were studied: 52 males and 50 females. Their mean age was 55.4 years.

The operative procedures included major elective abdominal surgery, aortic reconstruction, emergency abdominal surgery, and esophageal resections. Eighty patients had normal preoperative chest X-ray. Twenty-two patients had COPD or other chronic pulmonary conditions. Sixty-nine patients had no postoperative pulmonary complications. Pneumonia developed in 31(30.4%) patients, pulmonary edema in one, and pleural effusion in another. Thirteen of 102 patients (12.7%) died. Fifty-eight patients received 9 ml/kg and 44 received 14 ml/kg tidal volume. Their characteristics are shown in the Table.

Table

Two patients in the 9 ml/kg group and one patient in the 14 ml/kg group died from pneumonia. One of eight patients in the 9 ml/kg group and four of seven patients in the 14 ml/kg group died from septic shock due to gangrene or perforation of the GI tract with peritonitis.

Conclusion

The use of large tidal volume for postoperative mechanical ventilation does not increase postoperative complications or mortality.