This month in Pediatric Anesthesia, Andre Wolf presents a review of a common case in WAC's practice, ductal ligation in the very low birth weight infant. While this anesthetic could be described as "plug and play" there are multiple hazards that stand between optimal and sub-optimal outcome for the child. Wolf describes the current understanding in a succinct and easily retained format.

Oxygenation, both hyper and hypo, is critical in the NICU population. Of concern is the effect of hyperoxia on retinopathy, intraventricular hemorrhage (IVH), and periventricular leukodystrophy (PVL). Ultimately, the task becomes balancing the risk of hypoxia versus neurodevelopmental impairment associated with hyperoxia. Data is mixed in this area. If oxygenation is defined as low in saturations ranging 85-95% and high in the range of 91-95%, lower levels of retinopathy and improved neurodevelopment are found at 18 months of age in the low saturation groups while carrying a higher mortality rate in this same group. The issue of bronchopulmonary dysplasia (BPD) is addressed as well. Briefly stated, lower oxygen levels are generally associated with lower rates of BPD. Interestingly, BPD data is gathered from infants revived at blue baby births with either 30% or 90% oxygen. If this brief intervention yields a noticeable difference in lung development, it stands to reason that our anesthetic may influence outcome in a similar fashion, however brief our interaction with the child.

Pain management is a second area of concern in these children. Lack of pain control manifests as negative nitrogen balance and increased postoperative complication rate.
Fentanyl is widely used in this arena given concern for volatile anesthetic mediated neuronal apoptosis as well as its positive hemodynamic profile. Regimens of high bolus dosing (100 mcg/kg) are compared to intermediate bolus (25 mcg/kg) and low bolus with infusion (10-25 mcg/kg + 5-10 mcg/kg/hour) dosing. 25 mcg/kg is described as blunting negative physiologic consequences of surgery while 10-25 mcg/kg with infusion is noted to blunt hemodynamic response but not described as favorably as 25 mcg/kg. High dose (100 mcg/kg) is noted to yield hemodynamic instability.

The final issue this document will discuss is Wolf's writing on near-infrared spectroscopy (NIRS). This monitor, currently used in adult cardiac surgery at WMC, employs technology very similar to pulse oximetry to measure oxygenation at the superficial cortex of the patient. It is generally regarded as a summaritive monitor of oxygen delivery in the neonate. If oxygen delivery greatly exceeds utilization, NIRS approaches 100%, if utilization exceeds supply NIRS approaches 0%. The tool itself resembles a BIS monitor and is no more invasive. This is an emerging technology in the neonatal arena with great promise but as yet limited objective support for its use.

Additional topics are covered by Wolf such as glucose homeostasis and carbon dioxide management. These topics can be viewed at your leisure.

Wolf touches on a big picture issue in neonatal anesthesia, that of the role of anesthesia in the neonatal population. Commonly our role is described as a necessary evil. Under this thought process, anesthesia is necessary for very ill children in very short bursts of time and as such is best when it is least involved. Consequently, The anesthetic becomes similar to a firecracker, simple and inelegant. Wolf questions this premise. He notes that everything about neonatology is carefully measured and deliberated toward the goal of achieving a homeostatic environment as conducive to proper development as the mother's womb. Why should the requirement for anesthesia necessitate a departure from this standard? The best anesthetic is one that seamlessly provides for a surgical intervention that promotes healing. God and nature can achieve this goal with beauty and grace. We mere mortals must labor to do the same, constantly appraising and improving our practice until we meet that standard.