Effect of low tidal volume ventilation on atelectasis in patients during general anesthesia: a computed tomographic scan.

STUDY OBJECTIVE: To determine whether low tidal ventilation in patients without lung injury results in an increase in the amount of atelectasis and a further impairment of gas exchange during general anesthesia.

DESIGN: Randomized, single-blind study.

SETTING: University hospital.

PATIENTS: 16 adult, ASA physical status I and II patients, who were scheduled for elective excision of intracranial lesion.

INTERVENTIONS: Patients were randomly allocated to one of two groups: traditional tidal volume (V(T)) ventilation group (V(T), 10 mL/kg) and low V(T) ventilation group (V(T), 6 mL/kg) after the first computed tomographic (CT) scan.

MEASUREMENTS AND MAIN RESULTS: Atelectasis, as determined by CT and arterial blood gas analysis, was measured before induction, after tracheal intubation, and at the end of operation. After tracheal intubation, CT scan showed atelectasis in both groups. The mean atelectasis area was 4.25 +/- 2.05 cm(2) (3.32% +/- 1.94%) in the traditional V(T) ventilation group and 5.56 +/- 3.21 cm(2) (4.19% +/- 2.31%) in the low V(T) ventilation group. At the end of operation, there was no significant increase in the amount of atelectasis within the two groups. Arterial blood gas analysis showed no differences after tracheal intubation or at the end of operation in either group.

CONCLUSION: Ventilation using low V(T)s does not cause more pulmonary collapse than mechanical ventilation using standard V(T)s.