Neonatal resuscitation: Improving the outcome (Proceedings)
Average reported neonatal mortality rates (greatest during the first week of life) vary, ranging from 9-26%. Prudent veterinary intervention in the prenatal, parturient and postpartum periods can increase neonatal survival by controlling or eliminating factors contributing to puppy morbidity and mortality. Poor prepartum condition of the dam, dystocia, congenital malformations, genetic defects, injury, environmental exposure, malnutrition, parasitism and infectious disease all contribute to neonatal morbidity and mortality. Optimal husbandry impacts neonatal survival favorably by managing labor and delivery to reduce stillbirths, controlling parasitism and reducing infectious disease, preventing injury and environmental exposure, and optimizing nutrition of the dam and neonates. Proper genetic screening for selection of breeders minimizes inherited congenital defects. The neonatal period can be divided into the prepartum (prenatal) period, parturition, and the postpartum neonatal period, we will focus on the latter here.
Immediate Post Partum Resuscitation
Optimal neonatal resuscitation following birth (if the dam fails to do so) or caesarean section involves the same "A-B-C's" as any cardiopulmonary resuscitation. First, prompt clearing of airways ("A") by gentle suction with a bulb syringe, and drying and stimulation of the neonate to promote respiration ("B"), and avoid chilling are performed. Neonates should not be swung to clear airways as described in the veterinary literature, because of the potential for cerebral hemorrhage from concussion. The use of doxapram as a respiratory stimulant is unlikely to improve hypoxemia associated with hypoventilation, and is not recommended. Spontaneous breathing and vocalization at birth are positively associated with survival through 7 days of age. Intervention for resuscitation of neonates following vaginal delivery should take place if the dam's actions fail to stimulate respiration, vocalization and movement within one minute of birth.Cardiopulmonary resuscitation for neonates who fail to breathe spontaneously is challenging yet potentially rewarding. Ventilatory support should include constant flow O2 delivery by facemask. If this is ineffective after one minute, positive pressure with a snugly fitting mask or endotracheal intubation and rebreathing bag (using a 2-mm endotracheal tube or a 12 to 16- gauge intravenous catheter) is advised. Anecdotal success with Jen Chung acupuncture point stimulation has been claimed when a 25-gauge needle is inserted into the nasal philtrum at the base of the nares and rotated when bone is contacted. Cardiac stimulation ("C") should follow ventilation support, as myocardial hypoxemia is the most common cause of bradycardia or asystole. Direct trans-thoracic cardiac compressions are advised as the first step; epinephrine is the drug of choice for cardiac arrest/standstill (0.2 mg/kg administered best by the intravenous or intraosseous route). Venous access in the neonate is challenging, the single umbilical vein is one possibility. The proximal humerus, proximal femur and proximomedial tibia offer intraosseous sites for drug administration. Atropine is currently not advised in neonatal resuscitation. The mechanism of bradycardia is hypoxemia-induced myocardial depression rather than vagal mediation, and anticholinergic induced tachycardia can actually exacerbate myocardial oxygen deficits.
Beyond The Abc's
Chilled neonates can fail to respond to resuscitation. Loss of body temperature occurs rapidly when a neonate is damp. Keeping the neonate warm is important during resuscitation and in the immediate post partum period. During resuscitation, placing the chilled neonate's trunk into a warm water bath (95 - 99°F) can improve response. Working under a heat lamp or within a Bair hugger warming device is helpful. Post resuscitation, neonates should be placed in a warm box (a styrofoam picnic box with ventilation holes is ideal) with warm bedding until they can be left with their dam.