Objective: : To determine whether infrared tympanic thermometry (ITT) measurements more accurately reflect core body temperatures than axillary, forehead, or rectal measurements during fever cycles in children.
Design: : Prospective cohort study.
Setting: : Pediatric and cardiac intensive care units at a tertiary care children's hospital.
Patients: : Critically ill children <7 yrs of age with indwelling bladder catheters.
Interventions: : Simultaneous temperatures were recorded during both febrile and nonfebrile periods using ITT, indwelling bladder (core), axillary, forehead, and indwelling rectal measurements in 36 children.
Measurements and main results: : Overall ITT measurements were 0.03 +/- 1.43 degrees F less than core temperature measurements. In comparison, rectal, forehead, and axillary measurements averaged 0.62 +/- 1.44, 0.56 +/- 1.81, and 1.25 +/- 1.73 degrees F less than core temperature measurements. ITT measurements had better agreement with core measurements during increasing and decreasing temperature cycles. Receiver operating characteristic analysis performed on increasing and decreasing temperature cycle data revealed that ITT measurements performed well, with an area under the curve of 0.855 (95% confidence interval, 0.797-0.913) in comparison with rectal measurement area under the curve of 0.777 (95% confidence interval, 0.701-0.853), forehead measurement area under the curve of 0.710 (95% confidence interval, 0.715-0.888), and axillary measurement area under the curve of 0.664 (95% confidence interval, 0.579-0.750).
Conclusions: : ITT measurements more accurately reflect core temperatures than any other measurement site during febrile and nonfebrile periods in children. ITT measurements are a reproducible and relatively noninvasive substitute for bladder or rectal measurements in febrile children.