NEONATAL RESUSCITATION POSTRESUSCITATION

THE IMMEDIATE POSTRESUSCITATION PERIOD
Maintenance of airway and ventilation
The goal of delivery room management is to stabilize the airway and assure effective oxygenation and ventilation. Once initial lung recruitment is obtained, it is essential to avoid overdistension. Breaths delivered by bag-mask ventilation may be difficult to control and may result in overdistension and consequent pneumothorax or pneumomediastinum. Additionally, the unheated nonhumidified oxygen can quickly cool the infant via the large surface area of the lungs, resulting in hypothermia. Therefore, mechanical ventilation should be initiated as soon as possible once the infant is stabilized.

Although the ideal mode of assisted ventilation is controversial, it is essential to provide adequate positive end-expiratory pressure to prevent atelectasis, while at the same time preventing overinflation.

Once the appropriate functional residual capacity is obtained, it is essential to use the lowest support possible to allow for adequate oxygenation and ventilation. Oxygen saturations should be monitored continually and arterial blood gas analyses performed as needed during the initial stabilization period. Saturations should be maintained in the 90-96% range for the term infant and 88-92% in the preterm infant after the initial stabilization.

Fluid and electrolyte management
In utero, nutrients are provided in their basic form. Glucose is the major energy substrate of the fetus. Fetal glucose uptake parallels maternal blood glucose concentration. The liver, heart, and brain receive the greatest cardiac output and, therefore, the greatest amount of glucose. The fetus uses glucose, lactate, and amino acids to store fuels that are used during transition. Neonates must develop a homeostatic balance between energy requirements and the supply of substrate as they move from the constant glucose supply of fetal life to the normal intermittent variations in the availability of glucose and other fuels. With the clamping of the cord, the maternal glucose supply is cut off. A fall in blood glucose during the first 2-6 hours of life occurs in healthy newborns. The blood glucose usually reaches a nadir and stabilizes at 50-60 mg/dL.

The immediate goal of fluid and electrolyte support following resuscitation is to maintain an appropriate intravascular volume and to provide glucose homeostasis and electrolyte balance. The neonatal cardiovascular system is very sensitive to preload, requiring adequate intravascular volume to maintain adequate cardiac output. Therefore, expansion of intravascular volume with appropriate solutions (eg, isotonic sodium chloride solution) often is considered in the neonate with inadequate blood pressure or perfusion.

Additionally, as discussed in previous sections, hypoglycemia may occur rapidly in critically ill or premature infants. Blood glucose determinations should be performed as soon as possible and a continuous infusion of glucose should be started at 4-6 mg/kg/min for those infants who are not able to tolerate enteral feedings. Dextrose boluses should be limited to symptomatic infants because they may result in transient hyperosmolarity and rebound hypoglycemia. Electrolytes, such as sodium, potassium, and chloride, should not be added initially because the fluid shifts from other body compartments allow for adequate electrolyte supply until adequate renal function is documented.

The practitioner should monitor the weight, clinical hydration status, urine output, and serum sodium concentrations closely because inappropriate fluid overload or restriction can lead to increased mortality and morbidity. Taking the infant's environment into account when calculating fluid requirements is very important. Fluid rates may be started at 60-80 mL/kg/d for the infant in a humidified incubator, while fluid rates may be much higher for the infant in a dry radiant warmer environment.

Preparation for transport
Preparation of the infant for transfer to a remote nursery for subsequent care requires several considerations. First, it is important to complete all the routine care that is required of newborn infants. These basics of care may be neglected in the rush to prepare the infant for transport, with potentially disastrous results. Following resuscitation, care must be taken to secure all lines, tubes, catheters, and leads for transport. Monitoring in the transport environment is only possible with functioning leads in place, which is frequently difficult. Rapid and complete documentation of the resuscitation and subsequent therapies also is required for future caretakers.