Effect of bilateral superficial parasternal intercostal block on intraoperative hemodynamics and oxygenation status in patients undergoing cardiac surgery via median sternotomy

The superficial parasternal intercostal block (SPIPB) has been used as a component of multimodal analgesia (MMA) in cardiac surgery. However, the impact of SPIPB on intraoperative hemodynamics and oxygenation status in patients remains insufficiently studied. Aim. To evaluate intraoperative changes in hemodynamics and oxygenation status in cardiac surgery patients using bilateral superficial parasternal intercostal block as a component of multimodal analgesia. Materials and methods. The study included 107 patients (mean age 60.3 ± 11.1 years) undergoing cardiac surgery with median sternotomy under cardiopulmonary bypass (CPB). Patients were allocated to two groups according to the MMA protocol: group 1 (n = 76) received fentanyl, paracetamol, lidocaine, and ketorolac; group 2 (n = 31) received bilateral SPIPB with paracetamol, lidocaine, and ketorolac, with fentanyl administered on demand. Systemic and central hemodynamic parameters were compared between the groups; oxygen delivery index (DO2I) and oxygen consumption index (VO2I) were calculated; and the use of vasoactive / inotropic agents was analyzed. Statistical processing was performed using Statistica and Microsoft Excel 2013. Results. At baseline, mean arterial pressure (MAP) and heart rate (HR) did not differ significantly between the groups (MAP: 92.6 ± 11.3 mmHg vs 83.7 ± 12.3 mmHg; HR: 75.0 ± 10.5 bpm vs 69.0 ± 13.8 bpm). At the sternotomy stage, systolic arterial pressure and HR decreased in group 2 (106.0 [102.0; 123.0] mmHg and 62.0 [54.0; 70.0] bpm) and increased in group 1 (132.0 [127.5; 138.5] mmHg and 84.5 [76.0; 91.0] bpm), respectively (p < 0.001). At the end of the operation, HR did not differ between the two study groups (p = 0.307), whereas systolic arterial pressure was lower in group 2 (p = 0.0057). At stages 4–7, MAP and HR values in group 1 exceeded those in group 2 by an average of 3–17 mmHg and 8–14 bpm (p < 0.001). Dopamine and/or noradrenaline were used less frequently in group 2, although doses did not differ significantly. After SPIPB, a non-significant decrease in stroke volume, cardiac output, and cardiac index was observed in group 2 (approximately 1.2-fold), whereas these parameters increased approximately 1.1-fold in group 1. Left ventricular ejection fraction was numerically but not significantly higher in group 2 after block placement (59.0 [48.0; 67.0] % vs 55.5 [48.0; 64.0] %, p = 0.549), and significantly higher at the end of surgery (72.0 [65.0; 76.0] % vs 67.0 [56.0; 71.5] %, p = 0.0005). DO2I in group 2 was higher than in group 1 at baseline (p = 0.001) but did not differ between groups at the end of surgery (p = 0.759). VO2I was comparable between groups before CPB (117.0 [113.0; 134.0] vs 114.0 [102.0; 143.0] ml·m-2·min-1, p = 0.533) and after CPB (108.0 [96.5.0; 110.0] vs 101.0 [84.0; 126.0] ml·m-2·min-1, p = 0.207). Conclusions. Bilateral SPIPB effectively prevents arterial hypertension and tachycardia at the sternotomy stage; however, its hemodynamic effect diminishes by the end of surgery. The block does not significantly affect the oxygen delivery or consumption indices in patients undergoing cardiac surgery via median sternotomy.