The hemodynamic effects of phenoxybenzamine in neonates, infants, and children.

STUDY OBJECTIVES: To evaluate the hemodynamic effects of the long-acting, alpha-adrenergic blocker, phenoxybenzamine, in children of different age groups. DESIGN: Retrospective chart review. SETTING: Tertiary-care, congenital cardiac surgery center. MEASUREMENTS: The data of 75 pediatric patients who received phenoxybenzamine while undergoing surgical repair of congenital heart defects on cardiopulmonary bypass (CPB) were studied. Patients were selected in three age groups: younger than one month (n = 25), one to 12 months (n = 25), and one to 5 years (n = 25). All patients received a full dose of phenoxybenzamine 1 mg/kg. Demographics, CPB duration, mean arterial pressure on CPB, mean flow on CPB (normalized to body surface area), and central-to-peripheral temperature gradients were recorded. Systemic vascular resistance index (SVRI) was calculated. MAIN RESULTS: Cardiopulmonary bypass duration was significantly longer in the age group of younger than 1 mo than in the older groups. Mean CPB flow/body surface area was similar in all children (3.45 +/- 0.9, 3.74 +/- 0.69, and 3.48 +/- 0.59 L/min/m2, respectively; P < 0.28). However, mean SVRI was significantly lower in children younger than 1 mo (997.3 +/- 233, 1196.9 +/- 394, and 1168.83 +/- 227 dynes/cm2m5; P < 0.04). Temperature gradient was significantly narrower in patients younger than one month than those who were one to 12 months and one to 5 years at the end of cooling (0.90 degrees C +/- 0.1 degrees C, 1.04 degrees C +/- 3.61 degrees C, 1.4 degrees C +/- 3.07 degrees C; P < 0.001) at end-rewarming and termination of CPB (4.58 degrees C +/- 2.36 degrees C, 6.23 degrees C +/- 4.17 degrees C, 7.32 degrees C +/- 3.46 degrees C; P < 0.02). Multivariate analysis showed that patient age was a significant variable affecting response to phenoxybenzamine, after adjusting for duration of CPB (P = 0.31), mean hematocrit on CPB (P = 0.86), and core cooling temperature (P = 0.34). CONCLUSION: The effect of phenoxybenzamine on SVRI, cooling, and rewarming on CPB varies with age as shown by more profound vasodilatation and narrower temperature gradients.

Comparison of phenoxybenzamine to sodium nitroprusside in infants undergoing surgery.

OBJECTIVES: The purpose of this study was to compare the effects of a direct-acting arterial dilator, sodium nitroprusside, to an alpha-adrenergic receptor blocker, phenoxybenzamine, in infants with congenital heart defects undergoing cardiac repairs on cardiopulmonary bypass. DESIGN: A prospective, multicenter, observational study. SETTING: Tertiary care center. PARTICIPANTS: Sixty infants scheduled for elective congenital cardiac surgery repair requiring cardiopulmonary bypass. INTERVENTIONS: Patients received either sodium nitroprusside 2 to 5 microg/kg/min infusion intraoperatively and in the intensive care unit (n=30 patients) or received phenoxybenzamine 1 mg/kg slowly intravenously at the onset of cardiopulmonary bypass (n=30 patients). MEASUREMENT AND MAIN RESULTS: Despite similar mean arterial pressures during cardiopulmonary bypass in both groups, infants who received phenoxybenzamine had a significantly higher flow compared with those who received sodium nitroprusside (180+/-4.8 v 73+/-5.12 mL/kg/min, p<0.0001). Base deficit was significantly larger in the sodium nitroprusside group compared with the phenoxybenzamine group intraoperatively and postoperatively (3.4+/-0.5 v 1.3+/-0.5 mEq/L, p<0.05). The core-to-peripheral temperature gradient was significantly larger in the sodium nitroprusside group compared with the phenoxybenzamine group intra- and postoperatively at all points studied. In the intensive care unit, the left atrial pressure was significantly higher in the sodium nitroprusside group compared with the phenoxybenzamine group (9+/-0.4 v 7+/-0.4 mmHg, p

Effectiveness of a circulating-water warming garment in rewarming after pediatric cardiac surgery using hypothermic cardiopulmonary bypass.

OBJECTIVE: To evaluate the effectiveness and safety of the ALLON 2001 microprocessor-based thermoregulation system in pediatric patients undergoing cardiac surgery requiring hypothermic cardiopulmonary bypass compared with the routine thermal care. DESIGN: Prospective randomized clinical study. SETTING: Single tertiary academic medical center. PARTICIPANTS: Infants (0-1 year) who underwent congenital heart surgery requiring hypothermic cardiopulmonary bypass (n = 18). Patients with open wounds and/or patients treated with an investigational drug or device within 30 days of surgery were excluded. INTERVENTIONS: Randomized use of thermoregulation system (warming garment, n = 9) or routine thermal care (control, n = 9) after separating from cardiopulmonary bypass until the arrival to the pediatric intensive care unit (PICU). MEASUREMENTS AND MAIN RESULTS: There were no statistically significant differences in the demographic data, cardiopulmonary bypass time, operating room time, incidence of deep hypothermic circulatory arrest, and cooling temperature between the groups. The nasopharyngeal temperature was significantly higher in the warming garment group after separation from cardiopulmonary bypass. Nasopharyngeal temperature at 20 minutes was 36.5 degrees C versus 35.01 degrees C (p = 0.0047), at 40 minutes was 36.98 degrees C versus 35.30 degrees C (p = 0.034), and at admission to the PICU was 36.09 degrees C versus 35.31 degrees C (p = not significant). There was no difference in the core-to-peripheral temperature gradient (nasopharyngeal-to-skin temperature) between the 2 study groups at any time point. No adverse events related to the use of the warming garment thermoregulation system were observed. CONCLUSION: The investigated thermoregulation system was effective in preventing the after-drop of temperature that occurs after cardiopulmonary bypass in small infants compared with routine warming methods.