Left ventricular-arterial coupling is associated with prolonged mechanical ventilation in severe post-cardiac surgery patients: an observational study

Background: Weaning post-cardiac surgery patients from mechanical ventilation (MV) poses a big challenge to these patients. Optimized left ventricular-arterial coupling (VAC) may be crucial for reducing the MV duration of these patients. However, there is no research exploring the relationship between VAC and the duration of MV. We performed this study to investigate the relationship between left ventricular-arterial coupling (VAC) and prolonged mechanical ventilation (MV) in severe post-cardiac surgery patients.

Methods: This was a single-center retrospective study of 56 severe post-cardiac surgery patients from January 2015 to December 2017 at the Department of Critical Care Medicine of Peking Union Medical College Hospital. Patients were divided into two groups according to the duration of MV (PMV group: prolonged mechanical ventilation group, MV > 6 days; Non-PMV group: non-prolonged mechanical ventilation group, MV ≤ 6 days). Hemodynamics and tissue perfusion data were collected or calculated at admission (T0) and 48 h after admission (T1) to the ICU.

Results: In terms of hemodynamic and tissue perfusion data, there were no differences between the two groups at admission (T0). Compared with the non-prolonged MV group after 48 h in the ICU (T1), the prolonged MV group had significantly higher values for heart rate (108 ± 13 vs 97 ± 12, P = 0.018), lactate (2.42 ± 1.24 vs.1.46 ± 0.58, P < 0.001), and Ea/Ees (5.93 ± 1.81 vs. 4.05 ± 1.20, P < 0.001). Increased Ea/Ees (odds ratio, 7.305; 95% CI, 1.181-45.168; P = 0.032) and lactate at T1 (odds ratio, 17.796; 95% CI, 1.377-229.988; P = 0.027) were independently associated with prolonged MV. There was a significant relationship between Ea/Ees_T1 and the duration of MV (r = 0.512, P < 0.01). The area under the receiver operating characteristic (AUC) of the left VAC for predicting prolonged MV was 0.801, and the cutoff value for Ea/Ees was 5.12, with 65.0% sensitivity and 90.0% specificity.

Conclusions: Left ventricular-arterial coupling was associated with prolonged mechanical ventilation in severe post-cardiac surgery patients. The assessment and optimization of left VAC might be helpful in reducing duration of MV in these patients.