Unilateral Ventilation on Cardiopulmonary Bypass During Cardiac Surgery

The aeration score of each lung is the sum of the aeration scores determined in each of six lung quadrants in each lung, which can range from 0 (normal ventilation) to 3 (atelectasis/consolidation).

Number of Kerley B lines in both lungs determined by chest x-ray where stage 1 (no Kerley B lines) reflects best outcome, stage 2 (Kerley B lines become visible) indicates interstitial edema, and stage 3 (increased number of Kerley B lines also in non-dependent areas and partially obscured in dependent parts of the lung) are a sign of alveolar edema.

Severity assessment will be semi-quantitative with 0 = no effusion, 1 = small effusion (with blunting of the basal lung segments and the costophrenic angle), 2 = moderate effusion (fluid extents to the mid-hemithorax creating a "meniscus sign"), and 3 = massive effusion (the whole lung appears opaque with displacement of the heart to the contralateral side if located unilaterally).

Global inhomogeneity is calculated as the sum of the absolute differences between the median value of tidal variation and every single pixel value, divided by the sum of all impedance values, to normalize the calculated values. A GI index closer to 0 represents highly homogeneous (even) ventilation. Higher values (i.e., > 0.5) indicate that some parts of the lung are over-distended while others are poorly aerated or collapsed (atelectasis).

The Horowitz index (HI) is calculated by diving arterial oxygen partial pressure determined in the blood gas by the fraction of inspired oxygen. It will be assessed after each blood gas check and the lowest HI during one day will be entered for further statistical analysis. The degree of impaired lung function will be determined as follows: HI > 300 mmHg (healthy lung function), HI between 201-300 mmHg (mild lung injury), HI between 101-200 mmHg (moderately severely impaired lung function), and HI < 100 mmHg (severe lung injury, ARDS).

Static lung compliance of the ventilated and the non-ventilated lung will be determined twice for each patient. Static compliance in healthy adults ranges between 60 and 100 mL/cm H₂O. Values below 50 mL/cm H₂O would be considered abnormally low.

Serum levels for HSP70, MMP-8, MMP-9, TIMP-1, and Lipocalin-2 will be determined in patients' blood samples, with normal values ranging from 0.2-3 ng/mL for HSP70, 0.3-1.2 ng/mL for MMP-8, 14-100 ng/mL for MMP-9, 80-150 ng/mL for TIMP-1, and 20-130 ng/mL for Lipocalin-2, respectively.

The duration from transfer to the intensive care unit until discharge to a step-down unit and the duration of hospitalization of the patient will be determined in days.

It will be recorded if the patient has been discharged from the hospital alive.

The hours between arrival of the intubated patient on the intensive care unit until extubation will be determined.

Any complication that poses a risk for the patient occurring during the hospital stay and having been documented in the patient's file will be retrieved by carefully reviewing the files and recorded.