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44134 - AGE AND SPONTANEOUS RESPIRATION WITH REMIFENTANIL

¹ BC Children’s Hospital, Vancouver, BC, Canada
² BC Children’s Hospital
³ BC Children’s Hospital
⁴ BC Children’s Hospital
⁵ BC Children’s Hospital

Abstract

INTRODUCTION:

Maintaining spontaneous ventilation in children, using total intravenous anesthesia, is often desirable, particularly for airway endoscopy. Spontaneous respiration with remifentanil has been reported in adults and children under sevoflurane anesthesia [1, 2]. We evaluated the effect of age on the dose of remifentanil tolerated during spontaneous respiration with anesthesia maintained using infusions of propofol and remifentanil.

METHODS:

Local IRB approval was obtained for this study. Forty-five children scheduled for strabismus surgery were divided by age into 3 groups (Group I: 6 months – 3 years, Group II: 3 years – 6 years and Group III: 6 years – 9 years). The propofol infusion was titrated using State Entropy as a pharmacodynamic end point and remifentanil infused, using a modified up-and-down method, with respiratory rate depression as a pharmacodynamic end point. A respiratory rate of just greater than 10, stable for 10 minutes, determined the final remifentanil infusion rate. The group mean was estimated from the final remifentanil infusion rate tolerated (RD50).

RESULTS:

The RD50 of groups I, II and III were 0.192 (0.08), 0.095 (0.04) and 0.075 (0.03) mcg kg-1min-1 respectively. Pairwise comparisons between the groups for the rate of remifentanil tolerated revealed a statistically significant increase in the RD50 in children less than 3 years of age compared to older children in groups II and III (p<0.001). The relationship between remifentanil dose and age, weight or height was not linear.

DISCUSSION:

Younger children, especially those aged less than 3 years, are more tolerant to the respiratory rate depressant effect of remifentanil. Total intravenous anesthesia with spontaneous ventilation is readily achieved in younger children and infants.

REFERENCES:

[1] Br J Anaesth 1998; 80: 509–11;[Abstract/Free Full Text]

[2] Paediatr Anaesth 2005; 15: 115–21[Medline]