Paediatric anaesthesia
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Ensuring adequate oxygenation of the developing brain is the cornerstone of neonatal critical care. Despite decades of clinical research dedicated to this issue of paramount importance, our knowledge and understanding regarding the physiology and pathophysiology of neonatal cerebral blood flow are still rudimentary. This review primarily focuses on currently available human clinical and experimental data on cerebral blood flow and autoregulation in the preterm and term infant. ⋯ Technical and ethical difficulties to conduct such trials leave us with a near complete lack of knowledge on how pharmacological and surgical interventions impact on cerebral autoregulation. The ensemble of these works argues for the necessity of highly individualized care by taking advantage of continuous bedside monitoring of cerebral circulation. They also point to the urgent need for further studies addressing the exciting but difficult issue of cerebral blood flow autoregulation in the neonate.
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This review article focuses on neonatal respiratory physiology, mechanical ventilation of the neonate and changes induced by anesthesia and surgery. Optimal ventilation techniques for preterm and term neonates are discussed. In summary, neonates are at high risk for respiratory complications during anesthesia, which can be explained by their characteristic respiratory physiology. ⋯ Ventilatory strategies should ideally include application of an 'open lung strategy' as well avoidance of inappropriately high VT and excessive oxygen administration. In critically ill and unstable neonates, for example, extremely low-birthweight infants surgery in the neonatal intensive care unit might be an appropriate alternative to the operating theater. Best respiratory management of neonates during anesthesia is a team effort that should involve a joint multidisciplinary approach of anesthetists, pediatric surgeons, cardiologists, and neonatologists to reduce complications and optimize outcomes in this vulnerable population.
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Both coagulopathy and abnormal thrombosis can complicate the anesthetic and surgical management of neonatal patients; however, the patterns of bleeding and thrombosis in neonates differ from those in adults or older children. Severe coagulopathic bleeding most commonly occurs during heart surgery and almost certainly contributes to morbidity and mortality in this population. Such severe bleeding is rare during other surgery; the exception is babies presenting to the operating room with established coagulopathy secondary to severe sepsis. ⋯ This review will discuss important differences between the coagulation system of neonates and older patients and how these relate to newer models of coagulation. The emphasis will be on issues likely to impact on perioperative care. In particular, the management of severe bleeding, the manipulation of coagulation during heart surgery, and the management of coagulopathy in septic neonates will be discussed in detail.
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The physiology of the neonate is ideally suited to the transition to extrauterine life followed by a period of rapid growth and development. Intravenous fluids and electrolytes should be prescribed with care in the neonate. Sodium and water requirements in the first few days of life are low and should be increased after the postnatal diuresis. ⋯ More studies are required to guide fluid management in neonates, particularly in those with sepsis or undergoing surgery. A balanced salt solution such as Hartmann's or Plasmalyte should be used to replace losses during surgery (and blood or coagulation factors as indicated). Excessive fluid administration during surgery should be avoided.
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Paediatric anaesthesia · Jan 2014
ReviewLimitations and vulnerabilities of the neonatal cardiovascular system: considerations for anesthetic management.
Development of the cardiovascular system through the last trimester of pregnancy and the subsequent neonatal period is profound. Morphological changes within the myocardium make the heart vulnerable to challenges such as fluid shifts and anesthetic drugs. ⋯ There is now a better understanding of the limitations of blood pressure homeostasis in the neonate and the potential consequences of marginal hypoperfusion. This article highlights some of these vulnerabilities particularly as they relate to anesthesia and surgery in the very young.