Background
Objectives
Methods/design
Trial design
Participants
Eligibility criteria | |
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Inclusion criteria • Age ≥18 years • Ability to provide informed consent • Elective cardiac surgery • Surgical intervention performed with CPB, aortic cross-clamping and cardioplegic arrest • Valvular surgery, coronary surgery, surgery on the ascending aorta, combined cardiac surgery • Median sternotomy and bi-pulmonary ventilation | Exclusion criteria • Patient’s refusal • Nonelective cardiac surgery • Previous cardiac surgery • Anticipated circulatory arrest, aortic endoprothesis, TAVI, Mitraclip • Thoracotomic approach, with one lung ventilation • Patients with BMI >30 [24] • Patients with end-stage chronic kidney disease (defined as need for dialysis) • Patients with known respiratory diseases (ongoing respiratory infections, asthma, COPD, OSAS) • Patients already intubated before arrival in operating theatre • Pneumonia in the previous 30 days • Previous pulmonary resection • Patients with a preoperative oxygen saturation <90%, or PaO2 < 60 mmHg without supplemental oxygen, or a PaO2/FiO2 ratio <300, or PaCO2 > 45 mmHg • Patients with hepatic disease, defined as elevated liver enzymes (higher than two reference intervals) • Patients with pulmonary hypertension (defined as preoperative estimated systolic pulmonary artery pressure >45 mmHg) |
Endpoints
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Readmission to the ICU for RF
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The global incidence of PPCs after cardiac surgery (see Table 2 for complete definition)Table 2Definition of postoperative pulmonary complications (PPCs)ComplicationDefinitionRespiratory insufficiencyAt least one of the following criteria:• SpO2 < 90%• PaO2/FiO2 < 300• PaCO2 > 45 mmHg• Dyspnea with respiratory distress or use of accessory musclesRespiratory infectionEvidence of new pulmonary infiltrates on chest radiograph plus at least two of the following Johanson criteria:• Body temperature >38 °C or <35.5 °C• White blood cell count >12,000 mm3 or <4000 mm3• Purulent sputum• Presence of a new or evolving infiltrate on chest radiograph within 7 days after surgeryPleural effusionEvidence of new hazy opacity of onehemithorax with preserved vascular shadows on the supine radiograph, or posterior costophrenic angle blunting on a lateral chest radiograph, or evidence of a new hypo-anechoic area between visceral and parietal pleura on chest ultrasonographyAtelectasisEvidence on chest radiography of new parenchymal thickening surrounded by hyperinflated lungAspiration pneumonitisInhalation of gastric content in the perioperative period with subsequent acute lung injuryBronchospasmNew expiratory wheezing responsive to treatment with bronchodilatorsPneumothoraxPresence of air within the pleural space detected with chest radiograph or loss of lung sliding of gliding sign on ultrasonographic lung examination
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Need for re-intubation
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Need for noninvasive ventilation
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Duration of mechanical ventilation
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Length of the ICU and hospital stay
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Cardiovascular complications
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Short-term and long-term mortality
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Postoperative infections
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Postoperative residual curarization (PORC): measured with a Train of Four (TOF) and defined as a “need for pharmacological reversal”
Interventions (randomization and treatment protocol)
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First arm. No mechanical ventilation during CPB: patient will be disconnected from the respiratory circuit
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Second arm. Patients will receive CPAP with PEEP of 5 mmH2O and FiO2 < 80%. To perform CPAP the ventilator will be set in manual/spontaneous mode, with a flow of 1–2 L/min and the adjustable pressure valve (APL) set at 5 cmH2O. The actual pressure will be checked with a pressure gauge integrated in the ventilator and a pressure gauge connected to the proximal end of the endotracheal tube
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Third arm. Patients will be ventilated with a respiratory rate of 5 acts/min, with tidal volume (TV) of 2–3 mL/Kg of ideal body weight (IBW) and PEEP of 3–5 cmH2O
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Tidal volume (TV) = 6–8 ml/Kg of IBW [22]
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PEEP = 5 cmH2O
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FiO2 < 80%
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I:E = 1:2 (inspiration:expiration ratio)