ANESTHESIA FOR NEUROSURGERY IN CHILDREN AND INFANTS

Abstract

Summary L ittle is known about physiology of the cerebral circulation in the newborn and infant human. Data must be extrapolated from current knowledge of the physiology of human adults and animals. While normal newborn infants probably autoregulate CBF in response to changes in MAP, the autoregulatory limits are undefined; their cerebral circulation is less responsive to hypocapnia than that of adults. Surgery and anesthesia induce considerable emotional stress on both parents and children. So, the pediatric anesthesiologist the physiologic well-being of patients. In addition, the assessment and documentation of neurologic impairment and risk of intraoperative complication must be addressed. One of the central importance in the preoperative assessment is for anesthesiologist to determine whether elevated ICP is present, to assess whether a risk for regurgitation and aspiration exists, and to anticipate what surgical positioning will be required and to know its impact on anesthetic management. Premeditation is generally withheld from children undergoing neurosurgery. Sedatives and opioids should never be administered to an unmonitored patient. Also, induction of general anesthesia should be planned to minimize the risk of inducing sustained, life threatening intracranial hypertension. Anesthesia in these children should be induced with intravenous agent to minimize the risk of aspiration and reduce ICP. The general principles of fluid management for neurosurgical anesthesia are (1) to maintain normovolemia and (2) to avoid reduction of serum osmolarity. The first principle is a derivative of the concept presented earlier that it is an general idea to maintain a normal MAP in patient undergoing most neurosurgical procedures. Maintaining normovolemia is simply one element of maintaining a normal MAP, the second principle is a derivative of the common observation that lowering serum osmolarity results in edema of both normal and abnormal brain. In general, intravenous anesthetic, analgesic sedative agents except Ketamine are associated with parallel reduction in CBF and cerebral metabolic rate (CMR) and have no adverse effect on intracranial compliance. Also, all the volatile agents cause dose dependent cerebral vasodilatation which affected by other administered drugs and the physiologic status of patients. Nitrous oxide (N2O) is also a cerebral vasodilator, the CBF effect of which is greatest when it is administered as a sole agent, least when it administered against a background of narcotic, Propofol, benzodiazepines and intermediate when administered in conjunction with volatile agents. Nonetheless, experience dictates that both N2O and volatile agents, the later usually in sub-MAC concentrations, administered in components of a balanced anesthetic technique in combination with narcotics, can be used in most elective and many emergency neurosurgical procedures. Exceptions are rare. Methods of treating postoperative pain in children include the use of systemic analgesic and local anesthetic agent. The systemic analgesic can be divided into non opioids and opioids. The none opioids analgesic for mild or moderate pain and the opioids for sever pain.children are sensitive to opioids for severe pain. Children are sensitive to opioids and doses should be reduced accordingly. They should not e given to children less than 5 Kg. Local anesthetic techniques by local wound infiltration with bupivacaine 0.25% at the conclusion of surgery is very effective and is extremely simple and safe. It reduces the need for additional measure.