Sodium nitroprusside infusion after bidirectional superior cavopulmonary connection: preserved cerebral blood flow velocity and systemic oxygenation.
OBJECTIVE
Systemic hypertension is common in patients after bidirectional superior cavopulmonary connection. It can be treated with a vasodilator, such as sodium nitroprusside. However, it is possible that systemic hypertension is necessary to maintain cerebral blood flow in the face of cerebral venous hypertension. Furthermore, bidirectional superior cavopulmonary connection places the cerebral and pulmonary vascular beds in series. Thus treatment of systemic hypertension by lowering blood pressure might decrease cerebral blood flow, pulmonary blood flow, and systemic oxygen levels. The aim of the current study was to determine the effects of sodium nitroprusside on cerebral blood flow velocity and systemic oxygenation in patients after bidirectional superior cavopulmonary connection.


METHODS
This is a prospective patient-controlled study of 9 patients (median age, 7 months; age range, 4 to 12 months) undergoing bidirectional superior cavopulmonary connection. Patients were studied in the intensive care unit within 6 hours of surgical intervention while sedated, paralyzed, and mechanically ventilated. Sodium nitroprusside was infused to achieve a decrease in mean systemic blood pressure of approximately 20%. Cerebral blood flow velocity was measured by means of transcranial Doppler ultrasonography of the middle cerebral artery.


RESULTS
During sodium nitroprusside infusion, mean systemic blood pressure decreased (from 69 +/- 6 mm Hg at baseline to 58 +/- 6 mm Hg, P <.05). However, there was no accompanying change in 2 indicators of cerebral blood flow: blood flow velocity in the middle cerebral artery and arteriovenous oxygen saturation difference across the upper body. Both arterial Po(2) and systemic oxygen saturation were also preserved during sodium nitroprusside infusion.


CONCLUSIONS
Sodium nitroprusside decreases systemic blood pressure in patients after bidirectional superior cavopulmonary connection. This decrease occurs without accompanying changes in cerebral blood flow velocity or systemic oxygen levels. These findings suggest that cerebral and pulmonary blood flows are preserved during sodium nitroprusside infusion. Sodium nitroprusside appears to be an appropriate agent for the treatment of systemic hypertension after bidirectional superior cavopulmonary connection.
Simsic
Janet M
JM
Division of Pediatrics, Medical University of South Carolina, Charleston, USA. simsicj@kidsheart.com
Bradley
Scott M
SM
Mulvihill
Denise M
DM
D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005260:Female; D018610:Heart Bypass, Right; D006330:Heart Defects, Congenital / Q000097:blood / Q000503:physiopathology / Q000628:therapy; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007223:Infant; D007229:Infant Welfare; D007262:Infusions, Intravenous; D008297:Male; D009599:Nitroprusside / Q000627:therapeutic use*; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D016896:Treatment Outcome
D000959:Antihypertensive Agents; D009599:Nitroprusside; D010100:Oxygen