A new system for assessing atelectasis on chest x-ray after sternotomy for cardiac surgery

Background: Pulmonary atelectasis is common following sternotomy for cardiac surgery. The degree of atelectasis present on chest x-ray has been used to assess efficacy of interventions designed to reduce atelectasis, however radiological atelectasis scoring systems used may exaggerate the clinical effect of atelectasis in these patients. We have produced an alternative scoring system that seeks to correct this problem and this study aimed to evaluate this. Methods: Following ethics approval we retrospectively selected 50 consecutive patients admitted to the intensive care unit following cardiac surgery. Electronic copies of chest x-ray taken on return to the intensive care unit, on day 1 and day 3 postoperative were obtained and corresponding details of oxygenation were collected from patient records. Anonymised chest x-ray’s were scored, using both the old and new scoring system, by a radiologist blinded to the clinical data. Chest x-ray scores were compared with oxygenation indices at the time of chest x-ray. Day 1 scores were also assessed for their ability to reflect day 3 oxygenation indices and supplemental oxygen requirement. Results: The new score demonstrated better ability to detect atelectasis on chest x-ray and better specificity than the old score when comparing the chest x-ray findings with the clinical oxygenation status of the patients. The new score also performed better at predicting day 3 oxygenation status from the day 1 chest x-ray. Conclusions: This new scoring method performed better as an outcome measure for atelectasis in studies of patients following cardiac surgery. It may also better identify patients who require ongoing administration of supplemental oxygen on postoperative day 3.