Acute effect of sildenafil on central hemodynamics in mechanically ventilated patients with WHO group III pulmonary hypertension and right ventricular failure necessitating administration of dobutamine

Background/ObjectivesSildenafil decreases pulmonary vascular resistance index (PVRI), in patients with pulmonary hypertension (PH). We investigated sildenafils' effects on central hemodynamics of mechanically ventilated patients with WHO group-III PH and RV failure necessitating dobutamine administration.MethodsProspective non-controlled study involving 12 (9 males, 59 ± 4 years old), patients with the above characteristics. All patients in phase-1 (days 1-2) received dobutamine (5 μg/kg/min IV). During phase-2 (days 3-6), sildenafil was started via nasogastric tube (80 mg/day) and dobutamine discontinuation was attempted. Patients were designated responders or non-responders based on whether dobutamine could be stopped or not. Phase-3 lasted from day 7 to day of weaning from mechanical ventilation; or if weaning failed, until day 20 following admission (end-of-study). Invasive and echocardiographic parameters were repeatedly recorded throughout the study.ResultsSignificantly changed parameters (P < 0.025) from baseline to phase-1, -2 and -3 (%change of mean ratios), in responders (n = 7) included among others PVRI (− 40%, − 51%, − 42%), RV stroke work index (RVSWI: 43%, 79%, 41%) and cardiac index (49%, 54%, 48%), which also differed significantly from non-responders (N = 5). In phases-1 and -3 non-responders had not significant changes, in phase-2 PVRI (27%) and RVSWI (− 22%) changed significantly. In contrast to non-responders, all responders were weaned from mechanical ventilation until the end-of-study (P < 0.025).ConclusionsSildenafil may improve central hemodynamics and RV function indices in ventilated patients with WHO group-III PH and RV failure requiring dobutamine infusion, when they respond favorably to the latter. Accordingly, an adequate RV systolic reserve may be mandatory for sildenafil to exert its actions.