An approach to using central pupils as a clinical sign to assess depth of anesthesia in infants undergoing fundus examination with inhalation of sevoflurane.

STUDY

OBJECTIVE

To determine whether depth of anesthesia correlates with central pupils in outpatient infants undergoing fundus examination during general anesthesia.

DESIGN

Prospective, clinical comparison study.

SETTING

Outpatient operating room of a university-affiliated hospital.

PATIENTS: Premature infants with corrected gestational ages of 44 - 64weeks, who met the criteria for screening for eye examination for retinopathy.

INTERVENTIONS: Body movement and central pupils were used as clinical signs. Patients were assigned to one of two groups: the body movement group (Group M) and the central pupils group (Group C). Anesthesia was induced with inhalation of 6% sevoflurane, and time to loss of movement was recorded as the induction time. Following induction, the inspired concentration of sevoflurane was adjusted to the maintenance concentration. The up-and-down method was used to determine the subsequent concentration. The initial maintenance concentration was 3% in both groups. In Group M, no movement response was recorded as (+) while movement response was recorded as (-). The gradient of increase or decrease was 0.5%. If the preceding subject did not move, the sevoflurane maintenance concentration was decreased by 0.5%. In Group C, the central pupils were recorded as (+) and non-central pupils were recorded as (-). The method used to determine the sevoflurane concentration given to premature infants in Group C was the same as in Group M.

MEASUREMENT: Induction time, anesthesia duration, and time to recovery after anesthesia were recorded. The presence of purposeful movement and central pupils were recorded in both groups.

MAIN RESULT: 27 pediatric outpatients completed the investigation in Group M, and the effective inhalation concentrations in 5650% of patients (EIC50) value of sevoflurane was 3.0%. Thirty-one patients completed the investigation in Group C, and the EIC50 value of sevoflurane was 3.4%. The pediatric outpatients with central fixation of the pupils did not move during the examination.

CONCLUSION

Central pupils are a reliable clinical indicator to assess adequate anesthetic depth in preterm infants during sevoflurane anesthesia.