Acute Respiratory Distress Syndrome Diagnosis after Coronary Artery Bypass: Comparison between Diagnostic Criteria and Clinical Picture

Acute Respiratory Distress Syndrome (ARDS) is a potential complication of cardiac surgery, given that patients undergoing CABG frequently have hypoxemia and pulmonary dysfunction during initial hours after surgery. Thus, ARDS criteria in these patients are more likely to be positive while these criteria may not match the patient`s clinical picture. We aimed to investigate frequency of rapid onset hypoxemia in Pressure of Arterial Oxygen to Fractional Inspired Oxygen Concentration (PaO2/FiO2) less than 200 and diffuse pulmonary infiltrates as two diagnostic criteria forwards and compared these criteria with the clinical picture of the patients after Coronary Artery Bypass Graft (CABG) in this study. The study was prospective case series which carried out in about six months. All patients admitted to intensive care unit of Tehran Heart Center, who had undergone CABG on cardiopulmonary pump (CPB) recruited in the study. After considering inclusion criteria, age, sex, duration of intubation, arterial blood gas and chest radiography, on 24 hours and 48 hours after admission to the ICU were recorded. Then, patients with rapid onset of hypoxemia (PaO2/FiO2≤200mmHg) and diffuse pulmonary infiltrates and without sign or symptoms of obvious heart failure (probable positive ARDS cases) criteria were recorded and comparison between these probable positive cases with clinician`s clinical diagnosis (blinded to the study) was performed. In this study, a total of 300 patients after on-pump coronary artery bypass surgery were included. Postoperatively, 2 (0.66 %) in the 24 hours and 4 (1.33%) patients in 48 hours after surgery were positive for the two ARDS criteria according to the checklists, but; nobody had saved persistently ARDS criteria persistently during 48 hours after surgery. At the same time, clinician did not report any case of ARDS among 300 patients. In this study patients with ARDS criteria had no significant differences in age (P.value=0.937) and sex (P.value=0.533). Duration of intubation in patients with ARDS (14.26 ± 4.25 hours) in the first 48 hours was higher but not statistically different from the group without ARDS (11.60 ± 5.45 hours) (P.value=0.236). ARDS diagnosis based on rapid onset of hypoxemia (PaO2/FiO2≤200 mmHg) and diffuse pulmonary infiltrates and without signs or symptoms of obvious heart failure criteria in patients undergoing CABG could lead to overdiagnosis or misdiagnosis in less than 24 hours follow up. We recommend following patients for more than 24 hours and revise the current ARDS criteria for CABG patients.