Table 3. Primary and Secondary Outcomes.
| Outcomes | No. of events/total (%) | Absolute difference (95% CI) | P valuea | |
|---|---|---|---|---|
| Low tidal volume (n = 614) | Conventional tidal volume (n = 592) | |||
| Primary outcome | ||||
| Composite respiratory complications within 7 d | 231/608 (38.0) | 232/590 (39.3) | −1.3 (−6.8 to 4.2)b | .64 |
| Components of the primary outcome | ||||
| Atelectasisc | 150/608 (24.7) | 147/591 (24.9) | −0.2 (−5.1 to 4.7)b | .93 |
| Respiratory failured | 103/612 (16.8) | 109/590 (18.5) | −1.6 (−6.0 to 2.7)b | .45 |
| Pleural effusion | 67/611 (11.0) | 69/590 (11.7) | −0.7 (−4.3 to 2.9)b | .69 |
| Pneumonia | 19/610 (3.1) | 22/591 (3.7) | −0.6 (−2.7 to 1.5)b | .56 |
| Unplanned noninvasive or invasive ventilation | 15/612 (2.5) | 14/591 (2.4) | 0.1 (−1.7 to 1.9)b | .92 |
| Pulmonary congestion | 10/612 (1.6) | 14/591 (2.4) | −0.7 (−2.4 to 0.9)b | .36 |
| Bronchospasm | 5/612 (0.8) | 5/590 (0.8) | −0.0 (−1.1 to 1.1)b | .95 |
| Pneumothorax | 2/611 (0.3) | 0/591 (0.0) | 0.3 (−0.1 to 0.8)b | .26 |
| Secondary outcomes | ||||
| Composite respiratory complications during hospital stay | 237/598 (39.6) | 239/579 (41.3) | −1.6 (−7.2 to 4.0)b | .56 |
| Pulmonary embolism | 5/595 (0.8) | 6/573 (1.0) | −0.2 (−1.4 to 1.0)b | .71 |
| Acute respiratory distress syndrome | 3/594 (0.5) | 0/574 (0.0) | 0.5 (−0.1 to 1.1)b | |
| Systemic inflammatory response syndrome | 6/612 (1.0) | 13/591 (2.2) | −1.2 (−2.8 to 0.2)b | .09 |
| Sepsis | 20/612 (3.3) | 13/591 (2.2) | 1.1 (−0.8 to 3.0)b | .26 |
| Acute kidney injurye | 36/420 (8.6) | 42/394 (10.7) | −2.1 (−6.2 to 2.0)b | .31 |
| Risk | 24/36 (66.7) | 32/42 (76.2) | ||
| Injury | 8/36 (22.2) | 4/42 (9.5) | ||
| Failure | 4/36 (11.1) | 6/42 (14.3) | ||
| Wound infection | 11/597 (1.8) | 10/575 (1.7) | 0.1 (−1.5 to 1.7)b | .89 |
| Intraoperative need of vasopressor | 518/600 (86.3) | 511/584 (87.5) | −1.2 (−5.0 to 2.7)b | .55 |
| Unplanned ICU admission | 30/595 (5.0) | 25/577 (4.3) | 0.7 (−1.7 to 3.2)b | .56 |
| Need for rapid response team call | 67/612 (10.9) | 63/591 (10.7) | 0.3 (−3.2 to 3.8)f | .87 |
| Length of stay, d | ||||
| ICU, mean (SD) | 0.5 (1.3) | 0.6 (3.5) | −0.1 (−0.4 to 0.2)f | .84 |
| Hospital, mean (SD) | 8.3 (8.6) | 7.9 (10.6) | 0.4 (−0.6 to 1.6)f | .40 |
| In-hospital mortality, No. (%) | 8 (1.3) | 7 (1.2) | 0.1 (−1.2 to 1.4)f | .85 |
Abbreviation: ICU, intensive care unit.
Calculated using the χ2 test for categorical variables or from a generalized linear model considering an inverse Gaussian distribution for the continuous variables.
Risk difference from a generalized linear model considering a binomial distribution with an identity link.
Defined as lung opacification with a shift of the mediastinum, hilum, or hemidiaphragm toward the affected area and compensatory overinflation in the adjacent nonatelectatic lung.
Defined as postoperative partial pressure of oxygen <60 mm Hg on room air, a partial pressure of oxygen/fraction of inspired oxygen ratio <300 mm Hg, or arterial oxygen saturation measured by pulse oximetry <90% and requiring oxygen therapy.
Classified in 3 categories according to stage of kidney injury. Risk is defined as an increase in creatinine 1.5 times baseline level; injury, an increase in creatinine 2 times baseline level; and failure, an increase in creatinine 3 times baseline level or an increase in creatinine of ≥0.5 mg/dL if baseline creatinine was ≥4 mg/dL.
Mean difference from a generalized linear model considering a Gaussian distribution.