Document Type : Original Article
Authors
1 Department of Anesthesia, Amrita School of Medicine, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, India
2 Respiratory Therapy Unit, Department of Anesthesia
Abstract
Objective: Fluids are administered to optimize hemodynamics during off-pump coronary artery
bypass grafting (CABG), which may lead to a positive fluid balance and increased lung water,
lung congestion, hypoxemia, prolonged mechanical ventilation, and longer hospital stays. Lung
ultrasound can assess extravascular lung water and help titrate diuretics and fluids, thus preventing
hypoxemia. The primary objective of this study was to study the correlation between B-line scores
measured by lung ultrasound and the PaO2/FiO2 ratio (the ratio of arterial partial pressure of oxygen
to fractional inspired oxygen) after off-pump CABG.
Methods: Forty off-pump CABG patients were included in this prospective observational study in a
tertiary care center from 2022 to 2023. The correlation coefficient from an earlier study was used to
calculate the sample size. A four-sector lung ultrasound was utilized for B-line scoring. B-line scores
and PaO2/FiO2 ratios were recorded at three time points: before the surgery commenced and at 24
and 48 hours post-operation. The fluid balance was calculated at 24 and 48 hours post-operation.
Pearson correlation coefficient was used to evaluate the correlation between B-line scores and fluid
balance with oxygenation, and its significance was assessed through a linear regression test.
Results: The PaO2/FiO2 ratio and B-line scores exhibited a statistically significant moderate negative
correlation at 24 hours post-surgery (r=-0.44; SD=-0.66, 95% CI=-0.66, -0.15; P=0.004) and a B-line
score exceeding 8 was associated with the lowest PaO2/FiO2 ratio. However, fluid balance and PaO2/FiO2
ratios revealed no correlation at 24 or 48 hours post-surgery. Additionally, fluid balance and
B-line scores demonstrated a moderate positive correlation after 48 hours but no correlation at 24
hours post-surgery.
Conclusion: B-line scores always negatively correlated with PaO2/FiO2ratios, and scores greater
than eight corresponded to the lowest ratio.
Keywords
- Coronary artery bypass
- Lung ultrasound
- Extravascular lung water
- Fluid therapy
- Hypoxia
- Diuretics
- Partial pressure
Main Subjects
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