INTRAOPERATIVE PAIN MANAGEMENT NEWBORN
Category: Pediatric Surgery
Abstract : INTRAOPERATIVE PAIN MANAGEMENT To a large extent, management of the surgical stress response in neonates can be accomplished with the same pharmacologic interventions that characterize anesthetic care of other surgical patients. Volatile anesthetic agents remain the most common means of providing anesthesia and analgesia intraoperatively. This is probably because they meet, at least to some deg
INTRAOPERATIVE PAIN MANAGEMENT
To a large extent, management of the surgical stress response in neonates can be accomplished with the same pharmacologic interventions that characterize anesthetic care of other surgical patients. Volatile anesthetic agents remain the most common means of providing anesthesia and analgesia intraoperatively.
This is probably because they meet, at least to some degree, each of the criteria required for a complete anesthetic, including some degree of hypnosis, amnesia, analgesia, and muscle relaxation. Anand demonstrated that blood levels of hormonal and metabolic indicators of the stress response were lower in neonates who received volatile anesthetics during surgery. Furthermore, clinical stability of neonates during and after surgery was improved by adequate administration of volatile anesthetic agents intraoperatively.
The relative potency of each volatile anesthetic agent is measured in terms of the minimum alveolar concentration (MAC) of an inhaled anesthetic agent at which 50% of patients do not have skeletal muscle movement in response to surgical incision or another noxious stimulus. The patient's age appears to influence the MAC of a given volatile anesthetic, and MAC is higher in infants than in any other age group. MAC may be 15-25% lower in neonates than in infants and is even lower in premature neonates.
Volatile anesthetic agents are potent myocardial depressants and vasodilators. Consequently, systolic blood pressure and mean arterial blood pressure may decrease when these agents are administered. In some neonates, other analgesic agents may be used to decrease volatile anesthetic agent requirements intraoperatively, thereby avoiding some of the hemodynamic changes that may occur with volatile anesthetic administration. In fact, surgical anesthesia can be accomplished without the use of any volatile anesthetic agents.
Narcotics are not complete anesthetic agents; they do not provide muscle relaxation or amnesia, which are essential functions of complete anesthetics. However, they are potent analgesic medications. Administration of these agents intraoperatively may be associated with less of a decrease in blood pressure in neonates than might occur with volatile anesthetic administration. Furthermore, narcotics are useful adjuncts to anesthetics based on volatile agents because they can reduce the volatile agent requirement, thereby reducing any hemodynamic lability.
Narcotic-based anesthetics are commonly used during cardiovascular procedures in neonates. Physicians should note that the pharmacokinetics of narcotics administered to neonates differs from that of older infants, children, and adolescents. Neonates have a lower clearance, greater volume of distribution, longer elimination half-life, and higher plasma concentration after narcotic boluses than older patients. Consequently, the postoperative disposition of neonates may be affected when narcotics are used intraoperatively. Narcotics commonly used for intraoperative analgesia in neonates include morphine, fentanyl, sufentanil, and remifentanil. Ketamine, a phencyclidine derivative, produces amnesia and intense analgesia.
This drug affects opioid receptors and N-methyl-D-aspartate (NDMA) receptors, as well as voltage-sensitive calcium ion channels as it induces its analgesic effects. Ketamine actually stimulates the cardiovascular system and thus is frequently associated with increases in both systolic and mean arterial blood pressure, as well as heart rate, when administered intraoperatively. While ketamine may not be associated with increased blood pressure in preterm neonates, it is certainly associated with smaller decreases in mean arterial pressure and systolic blood pressure than the other analgesic medications commonly used intraoperatively.
Beneficial effects of ketamine include production of bronchodilation and less depression of ventilation. Adverse effects that may occur in neonates include increased salivary and tracheobronchial secretion production, cerebral vasodilation, and apnea in neonates with increased intracranial pressure.
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