Cardiovascular effects of rectal methohexital in children.

STUDY OBJECTIVE

To define the cardiovascular effects of rectal methohexital in children with normal cardiac function.

DESIGN

Cardiovascular evaluation of each patient was performed before and after medication. Each patient's predrug results were used as control measurements for comparison with measurements made after methohexital administration.

SETTING

Inpatient operating room induction area in a privately endowed philanthropic children's hospital.

PATIENTS

Forty-seven children age 35 +/- 22 months (mean +/- SD) scheduled for elective orthopedic or plastic surgery, free of cardiac or pulmonary disease, and receiving no medication with central nervous system activity.

INTERVENTIONS

Control measurements of heart rate (HR), blood pressure (BP), and echocardiographic evaluations were obtained on the day before scheduled surgery. Repeat measurements were performed after the onset of methohexital-induced sleep. The time span of the measurements was designed to include the period of peak plasma methohexital concentration. In the preoperative holding area, 30 mg/kg of a 10% methohexital solution was administered rectally. If sleep did not occur in 15 minutes, an additional 15 mg/kg was given.

MEASUREMENTS AND MAIN RESULTS

HR increased markedly after rectal methohexital [126 +/- 23 beats per minute (bpm) to 144 +/- 21 bpm, p less than 0.001], and stroke volume (SV) decreased (24 +/- 9 ml to 21 +/- 8 ml, p less than 0.01). There were no significant changes in BP or cardiac index. The shortening fraction and ejection fraction remained within the normal range for this age-group.

CONCLUSIONS

Rectal methohexital induces sleep in healthy pediatric patients with minimal cardiovascular side effects. The primary effects are increased HR and decreased SV.