E. V. Suborov, E. A. Postnikova, A. A. Kapinos, V. V. Kuzkov, A. A. Smetkin, M. Yu. Kirov

Use of microstream capnography and alveolar recruitment during off-pump coronary artery bypass grafting

The aim of the study was to investigate changes in EtCO₂ and its correlation with PaCO₂, and cardiac function during off-pump coronary artery bypass grafting (OPCAB) and to evaluate whether the recruitment maneuver was effective in improving gas exchange after OPCAB. Twenty adult patients scheduled for elective OPCAB were enrolled in a prospective randomized study. Anesthesia was maintained with midazolam, propofol, and fentanyl. After OPCAB, the patients were randomized to a control group receiving conventional ventilation (n = 10) or to a RM group (n = 10) having ventilation and RM. RM was performed at min 15 after transfer to an ICU, by increasing airway pressure to 40 cm H₂O for 40 sec subsequently adjusting PEEP to a level of 2 cm H₂O above the lower inflection point of the pressure-volume curve. The measurements included hemodynamics, microstream capnography, respiratory parameters, and blood gasses. The baseline EtCO₂ correlated with PaCO₂ and cardiac index in both groups (r = 0.7 and 0.81, respectively; p < 0.05). In the control group, OPCAB was followed by a rise in PaCO₂ and worsening of arterial oxygenation (p < 0.05). After recruitment, EtCO2 increased transiently whereas PaO₂/FiO₂ returned to the baseline level. There was a moderate correlation between EtCO₂ and PaCO₂ before and after RM (r = 0.7 and 0.8, respectively; p < 0.05). The Bland-Altman analysis has shown that the difference between PaCO₂ and EtCO₂ was 1.9±11.4 mm Hg (M±2SD). Thus, during OPCAB, EtCO₂ measured by microstream capnography correlated well with PaCO₂ and cardiac function. The use of RM after OPCAB increases CO₂ elimination and improves arterial oxygenation.

Key words:  capnography, microstream; alveolar mobilization; aortocoronary bypass surgery

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