文档介绍：Neonatal Physiology and Anesthesia
Elena Brasoveanu, MD
Boston University
March 2, 2006
Pediatric Anesthesia
Origin in the 1930’s at Toronto Hospital for Sick Children when Robson described techniques only for children
Recognized subspecialty starting with 1946 when Robert Smith became director of anesthesia at Boston Children’s Hospital
Now, approximately 49 fellowship programs
Aspects of the Neonatal Physiology
The neonatal oxygen consumption is approximately 6 ml/kg/min versus 3 ml/kg/min in the adult
Even under normal circumstances the immature cardiac and respiratory systems must function near maximum to support this metabolic demand.
Respiratory Physiology
The respiratory system is not fully developed at birth and continues through early childhood.
Airways fully developed at 16 wks of gestation
Alveolarize at 24-28 wks plete maturation at 8 - 10 .
Respiratory Physiology (cont’d)
Increasing respiratory rate rather than tidal volume is more efficient to increase alveolar ventilation
The diaphragm is the primary respiratory muscle – has fewer high-oxidative muscle fibers and is less resistant to fatigue than the adult diaphragm
Respiratory Physiology (cont’d)
Awake FRC is similar, when normalized to body weight, to that of an adult
FRC declines during anesthesia bined with hypoventilation and increased consumption causes a rapid desaturation
Respiratory Physiology (cont’d)
Central apnea- self limited in newborns, approximately 5 seconds
Apnea of prematurity – 20 seconds or associated with desaturation episodes and bradycardia
Resolves at 50- 55 weeks gestational age.
Respiratory Physiology (cont’d)
Chest wall development
Ribs oriented parallel and unable to increase the thoracic volume during inspiration
At 2 ., associated with standing and walking, ribs are oriented oblique
Cartilaginous structure with inward movement during inspiration
Developmental Changes of the Rib Cage
Reproduced from - R. S. Litman: Pediatric Anesthesia – The Requis