Pulmonary abnormalities after cardiac surgery are better explained by atelectasis than by increased permeability oedema

Abstract

After cardiac surgery, mild pulmonary oedema is relatively common, even in the absence of high filling pressures, and is mainly attributable to a low COP, irrespective of increased permeability in about one-half of patients. It may prolong mechanical ventilation at EVLW > 10 ml/kg. However, pulmonary radiographic and ventilatory abnormalities may result, at least in part, from atelectasis rather than increased permeability oedema.

Minimally invasive aortic valve replacement reduces atelectasis in cardiac intensive care

“…In patients with radiographic evidence of atelectasis, the positive end-expiratory pressure and inspiratory oxygen fraction to maintain oxygenation need to be higher than in patients without radiographic evidence of atelectasis (7). Impairment of lung function can persist for one week after the operation (8).…”

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

“…Conversely, supine position, surgery and CPB led to elevations in VDE (Fig. 3), suggesting a substantial enlargement of the volume of the not ventilated but perfused alveoli due to persistent atelectasis after the CPB (33,34).…”

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

“…One study found that hypoxaemia was not present in most patients who had demonstrated atelectasis, with only 4% being unable to maintain an arterial oxygen tension of 13.3kPa [14] while another reports that the presence of atelectasis coincided with a requirement for higher positive end expiratory pressure (PEEP) and FiO 2 necessary to maintain oxygenation [17]. In this study it was found that the day 1 m-RAS was a good predictor of an S/F ratio of below 445 which would identify patients on supplemental oxygen therapy or those who had an SpO 2 <94% on day 3.…”