ECHOCARDIOGRAPHIC ESTIMATION OF PULMONARY CAPILLARY WEDGE PRESSURE LEVELS IN MECHANICALLY VENTILATED VERSUS SPONTANEOUSLY BREATHING PATIENTS WITH PULMONARY CONTUSIONS

Abstract

Pulmonary contusions mediated immunological lung injury characterized with interstitial involvement, as well as therapeutically applied positive pressures over the already damaged alveoli could lead to elevation of the pressures inside pulmonary circulation. Fifty patients were included in the study and divided into two groups, whereby 26 were mechanically ventilated while 24 were spontaneously breathing patients. In all patients Pulmonary Capillary Wedge Pressure (PCWP) was measured non-invasively using echocardiography. Measurements of Left Atrial Pressure (LAP) were made 24 hours after admission, on the 7th and 14th day of admission in the ICU. PCWP was calculated using the LAP values and the Nagueh formula (LAPx1.24+1.98). Lung ultrasound was used for the measurement of severity of the lung injury according to the BLUE Protocol. Mean values for PCWP were calculated in both groups and the difference was examined using the Student T Test. It was found that the values for PCWP did not differ significantly between the groups when measured 24 hours and 7 days after admission and mechanical ventilation initiation (t = -0.11 and 1.13 for value for p 0.45 and 0.13),but were significantly higher in mechanically ventilated patients after 14 days of mechanical ventilation commencement (mean 10.52 vs. 7.88, t=1.89 for p of 0.03). Lung injury in patients with pulmonary contusions, as well as inflammation during the process of damage and repair, involves interstitial changes which can lead to affection of small pulmonary vessels as well. Therapeutically applied positive pressure ventilation and alveolar distension could impair blood flow through small pulmonary capillaries and vessels. When both combined, they can lead to elevation of small circulation pressures. Mechanical ventilation in patients with pulmonary contusions is associated with higher PCWP after 14 days of positive pressure ventilation in comparison to spontaneously breathing patients. Duration of mechanical ventilation is associated with higher levels of PCWP.