Methods: A total of 25 patients (ASA I-II) who were planned to undergo operation due to chronic thromboembolic pulmonary hypertension were included in the study. Patients were divided into two groups (group 1 and group 2). Inhaled nitric oxide at 20 ppm was given to patients in group 1 (n=13) and group 2 (n=12) after induction. Pulmonary artery (PA) pressure, central venous pressure, heart rate, systolic arterial pressure, PA wedge pressure, cardiac index, and pulmonary vascular resistance (PVR) were recorded at minutes 10 (T₁) and 30 (T₂), after perfusion (T₃), and while sternal closure (T₄).

Results: In group 1 and group 2, PA mean systolic and diastolic pressures, and PVR were significantly lower compared to the initial period (T₀) (p<0.05). In group 1, cardiac index was significantly higher in T₁, T₂, T₃, and T₄ compared to T₀ (p<0.05). Mean PA pressure in both groups was statistically significantly lower than the initial value. While no difference was observed in both groups between T0 and T₁ periods, mean PA pressure was statistically significantly lower in other periods in group 1 (p=0.008). In group 1, mean PA pressure was significantly lower in T₁, T₂, T₃, and T₄ periods with respect to baseline value. In group 2, while a significant reduction was detected in T₁ period compared to baseline value, a significant reduction was detected in T₃ and T₄ periods compared to T₁ period (p=0.04). Although no significant differences were observed in PVR between the groups during T₀ and T₁ periods, PVR was significantly lower in group 1 in T₂, T₃, and T₄ periods (p=0.03).

Conclusion: We suggest that iNO is one of the most appropriate pulmonary vasodilator agents due to its pharmacological properties without causing adverse hemodynamic changes in thrombendarterectomy operations for chronic pulmonary hypertension patients.