Off-pump coronary bypass surgery adversely affects alveolar gas exchange.

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 60 +/- 10 years. The mean EUROScore was 3.8 +/- 2.9. 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.

Monitoring of fibrinolysis parameters during myocardial revascularization according to type of procedure.

The aim of the study was to assess the effect of cardiothoracic surgery on the dynamics of plasminogen, D-dimers and plasminogen activator inhibitor (PAI-I) during the first 24 h after surgery. The study included 14 patients operated with (on-pump) and 14 without (off-pump) the use of extracorporeal circulation (ECC). Blood sampling was carried out on induction of anesthesia (timepoint 1), on introduction of heparin (point 2) and protamine (point 3), at the end of surgery (point 4), and the next morning (point 5). Relative to point 1, the utilization of plasminogen at point 2 was 24% and 17% in the on-pump and off-pump groups, respectively (p=0.001 both). Increased D-dimer concentration from the baseline was more pronounced in the on-pump group (p=0.001). At point 5, D-dimer concentrations were comparable in both groups and different from baseline levels. PAI-I activity showed within-group differences from baseline at point 5 in the off-pump group (p=0.001), and at points 3 and 5 in the on-pump group (p=0.002 and 0.001, respectively). At point 5, the activity of PAI-I was comparable in both groups, yielding p=0.001 vs. baseline. Fibrinolysis was more pronounced and more dynamic in the on-pump group due to activation of the systemic inflammatory response induced by the use of ECC. In the off-pump group, fibrinolysis was a normal physiological response to the surgical procedure.