Anesthesia blocks nonshivering thermogenesis in the neonatal XXXX .

@entity3727 @entity1508 @entity43160 @entity26 @entity95 @entity3810 @entity6305 @entity3575 @entity912
Nonshivering thermogenesis (NST) is a normal physiological response of the neonate to cold exposure, characterized by increased blood flow to metabolically active brown fat stores. It is standard practice during neonatal surgery to warm the ambient environment in order to avoid consuming vital energy stores. While NST has been well-studied in the neonate, the response during anesthesia and @entity912 has not been fully characterized. @entity95 pups (aged 1 to 7 days) were randomized into several groups. The experimental groups consisted of animals mechanically ventilated and administered either @entity43160 , @entity6305 , curare, @entity3575 , @entity3810 ( @entity3727 ), or @entity1508 . The controls were spontaneously breathing animals. @entity26 consumption (VO2), an index of metabolic activity, was measured at thermoneutrality (39 degrees C) and after cold exposure (25 degrees C). Control and @entity43160 animals had a significant increase in VO2 in response to cold exposure. The increase in VO2 was not noted in animals that received curare, @entity6305 , @entity3575 , @entity3727 , or @entity1508 . To test the effect of anesthetic withdrawal during cold exposure on VO2, additional series of animals were studied. One group received continuous @entity1508 throughout the period of cold exposure; the other had cessation of the @entity1508 during cold exposure. Both groups were rewarmed subsequently. The animals that had withdrawal of @entity1508 during cold exposure had a marked and significant increase in VO2 compared with the control group (continuous @entity1508 ). VO2 returned to near-baseline levels upon rewarming. The authors conclude that many commonly used anesthetic and paralyzing agents inhibit the thermogenic response to cold exposure. However, cessation of anesthesia ( @entity1508 ) in a cold environment results in a marked increase in metabolic activity.
