Objective: To compare the response to dobutamine (DOB) of systemic, pulmonary, renal and mesenteric hemodynamics in healthy newborn piglets. Methods: Superior mesenteric artery (SMA) and left renal artery (RA) ultrasonic flow probes and a sheath were implanted into 16, 1-3 d old piglets. 2 d later, a thermodilution catheter was floated into the pulmonary artery (PA). SMA and RA flow (f), systemic arterial pressure (SAP), PA pressure and Cardiac Index (Q) were measured in awake animals. Vascular resistances (vr) were calculated. DOB doses of 5, 10, 20 and 50 μg/kg/min were used in random order for 30 min each. Results: Mean (SD) *= p<0.05 cf control. †=p<0.05 cf 5 μg/kg.min SVR fell with DOB but PVR was not affected. SMA blood flow and vascular resistance were unchanged at any dose. Table

Table 1
Full size table

Conclusion: Increasing DOB dosage causes progressively increasing Q with increasing heart rate but no increase in stroke volume, during 30 minute infusions. Increasing dose increases PAP. DOB causes systemic but not pulmonary vasodilatation leading to progressively falling SAP/PAP ratio. RAvr increases with high dose DOB.

The use of DOB for infants with pulmonary hypertension should be reassessed.