Predicting the efficacy of convection warming in anaesthetized children

Abstract

(i) Although the effectiveness of this warming technique is influenced by patient/procedure characteristics, these do not predict normothermia (uncertainty +/-28 min). Effectiveness is independent of simple thermal measures. (ii) Previously described measures of vasoconstriction are not valid in children. (iii) Our model shows children's thermal properties change with their T(core). However, key factors are unknown for an individual and our model does not predict heating efficacy. (iv) To minimize the risk of hyperthermia, we recommend continuous measurement of T(core) during convection heating. The device air temperature should be turned to medium (38 degrees C) as T(core) approaches 37 degrees C.

Is there thermal benefit from preoperative warming in children?

“…Given the spread of ages and weights in our study, it might be anticipated that morphology should influence both heat gain and loss more than it did, particularly because, compared to adults, high cutaneous thermal losses have been observed in children under anesthesia (12). However, we observed the same outcome in a previous study on T core behavior during convection warming (21). In that study, we found standard morphological indices had an error of ±28 min in predicting time to regain lost heat.…”

The effect of convective heating on evaporative heat loss in anesthetized children

“…The warmed children were heated by our previously described convective technique using a Bair Hugger set at 43°C (Bair Hugger; Arizant Healthcare Inc., Eden Prairie, MN, USA). This temperature was reduced as core temperature approached normothermia – although they remained convectively warmed.…”

“…Mean room RH was 52%. Descriptions of the accuracy of these measurements can be found in our prior publications . Data that were collected on various time periods, anthropometry, demographics, temperature, and RH are listed in Table .…”

“…Children with increased BMIs do not necessarily have a higher body fat and, because we did not measure body composition, we have reported the effect of EWL for three Cp's reflecting a range of body compositions : lean (3.65), mid (3.47), and obese (2.61).…”

“…The widely used technique of convective warming is effective in maintaining core temperature ( T core ) under general anesthesia (GA) . Evaporative heat loss (EHL) has been quoted at 10–24% total heat loss under thermoneutral conditions .…”