Original scientific paper
Off-Pump Coronary Bypass Surgery Adversely affects Alveolar Gas Exchange
Hrvoje Gašparović
Daniel Unić
Željko Sutlić
Ino Husedžinović
Bojan Biočina
Igor Rudež
Nada Nikić
Ivan Jelić
Abstract
While the introduction of off-pump myocardial revascularization (OPCAB) has initially shown promise in reducing
respiratory complications inherent to conventional coronary surgery, it has failed to eradicate them. Our study focused
on quantifying the lactate release from the lungs and the dysfunction at the level of the alveolar-capillary membrane precipitated
by OPCAB at different time points after the insult. Furthermore, we aimed to determine the impact of pulmonary
lactate production on systemic lactic acid concentrations. The study was conducted in a prospective observational
fashion. Forty consecutive patients undergoing OPCAB were analyzed. The mean patient age was 6010 years. The mean
EUROScore was 3.82.9. The alveolar-arterial O2 gradient increased from 19 range 9 to 30 to 26 range 20 to 34 kPa
(P<0.001) and remained elevated up to 6 hours after surgery. It rapidly declined again by 18 hours postoperatively. The
observed increase in the pulmonary lactate release (PLR) from a baseline value of 0.022 range –0.074 to 0.066 to 0.089
range 0.016 to 0.209 mmol/min/m2 at six hours postoperatively did not reach statistical significance (P=0.105). The
systemic arterial lactate (LS) concentration increased from 0.94 range 0.78 to 1.06 to 1.39 range 0.97 to 2.81 mmol/L
(P<0.001). The venoarterial pCO2 difference showed no significant change in comparison to baseline values. The mortality
in the studied group was 2.5% (1/40). The pulmonary lactate production showed a statistically significant correlation
with the systemic lactate concentration (R=0.46; P=0.003). Pulmonary injury following off pump myocardial revascularization
was evidenced by a prompt increase in the alveolar-arterial oxygen gradient. The alveolar-arterial O2 gradient
correlated with the duration of mechanical ventilation.
Keywords
off pump coronary artery bypass; lung injury; lactate; alveolar-arterial oxygen gradient
Hrčak ID:
23769
URI
Publication date:
8.5.2008.
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