Bohner 2002.
| Methods | Study was done in the hospitals of Heinrich‐Heine University, Germany | |
| Participants | Adults undergoing midline laparotomy for elective vascular surgery; abdominal aortic aneurysm surgery; and surgery of visceral, renal and iliac arteries or thrombectomy of IVC Excluded were emergency surgery, thoracoabdominal surgery or retroperitoneal approach Participants were randomly assigned to 2 groups with use of a random list: Control group: 105 participants; age, years: 64.5 ± 11.3; male/female: 82:23; BMI: 25.0 ± 3.3 Intervention group: 99 participants; age, years: 64.1 ± 12.3; male/female: 84:15; BMI: 25.4 ± 3.5 All participants received similar fluid regimen, analgesic routine and medications All participants were extubated soon after surgery and were admitted to intermediate care unit or intensive care unit |
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| Interventions | Control group: Oxygen was administered at ambient pressure via a non‐occlusive face mask, including mouth and nose or nose cannulas to keep oxygen saturation > 95%; FiO2 was adjusted to achieve this Intervention group: received prophylactic nCPAP. nCPAP mask was placed on admission to the unit, using a high gas flow source and a standard PEEP valve set at 10 cm H2O. FiO2 was adjusted to keep SpO2 > 95% and to keep nCPAP mask on for at least 12 hours |
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| Outcomes | Duration of intervention: 14.0 ± 4.3 hours Duration of follow‐up: longer than 7 days All‐cause mortality: control group, 0/105: intervention group, 4/99 Major respiratory complications as defined in individual studies Significant atelectasis: none reported Pneumonia: control group, 5/105: intervention group, 2/99 Respiratory failure: none reported Severe hypoxia: control group, 17/105: intervention group, 5/99 Severe delirium: control group, 12/105: intervention group, 6/99 Need for tracheal intubation and invasive ventilation: control group, 5/105: intervention group, 1/99 Readmission to ICU/IMC: control group, 14/105: intervention group, 6/99 Length of stay in hospital: control group, 11.81 ± 18.61 days: intervention group, 9.45 ± 6.79 days Cardiovascular complications (myocardial infarction, unstable angina, acute cardiac failure, arrhythmia): Cardiac arrest: control group, 2/105: intervention group, 1/99 Other postoperative complications (wound infection, anastomotic leak, renal failure): Renal failure: control group, 3/105: intervention group, 3/99 Adverse effects of the intervention (pulmonary aspiration, upper airway or facial injury): Nose ulcers: control group, 0/105: intervention group, 4/99 |
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| Notes | BMI = body mass index FiO2 = Inspired oxygen fraction IVC = inferior vena cava nCPAP = nasal CPAP PEEP = positive end‐expiratory pressure ICU = intensive care unit IMC = intermediate care unit No response to email |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Randomization using a random list |
| Allocation concealment (selection bias) | Unclear risk | Randomization using a random list, but no description of allocation concealment |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Anaesthesiologist at the operation site did not receive any information about the results of randomization; no evidence of anyone else being blinded |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Not described in the text |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Dropouts described because 9/99 participants did not want to continue with nCPAP after 5.75 ± 4.80 hours |
| Selective reporting (reporting bias) | Low risk | No evidence of selective reporting in text |
| Other bias | Unclear risk | None reported |