Neonatal Emergencies

Educational Objectives

The goal of this program is to improve the management of neonatal emergencies. After hearing and assimilating this program, the clinician will be better able to:

1. Characterize abnormalities of fetal development that lead to emergent conditions in neonates.

2. Optimize the perioperative treatment of neonates with emergent surgical conditions.

Summary

Fetal circulation: umbilical vein transports oxygenated blood to baby; arteries carry deoxygenated blood away; blood returning to baby bypasses liver through ductus venosus, travels to right atrium, passes through patent foramen ovale, and becomes systemic; mother (not fetal lungs) provides oxygenation; at birth, lungs expand, pulmonary vascular resistance decreases, and foramen ovale and ductus venosus close

Transition of circulation: from parallel fetal to series adult circulation; transition impeded by acidosis, hypothermia, and decreased 2,3-diphosphoglycerate; failed transition can result in demise or severe neurologic injury

Challenges for intubation: anatomic challenges include large tongue relative to airway and higher airway; vocal cords located at C3; cricoid narrowest part of airway and slanted; babies breathe within range close to closing volume; sedation can depress ventilation below closing volume and cause atelectasis; desaturation frequent during rapid-sequence induction

Intraventricular hemorrhage: neonates at increased risk; can cause hypotension; most common cause of cerebral palsy; many factors contribute to risk; anterior fontanelle closes at 16 to 18 mo; posterior closes at about 8 wk; severe intraoperative hypotension often caused by intracranial bleeding; fontanelle can become tense; contributing factors include hypoxia, hypercarbia, and changes in blood pressure, venous pressure, or hemoglobin level

Hemoglobin F: produced during fetal development; persists for ≈6 mo; has higher affinity for oxygen compared with adult form

Postoperative apnea: infants <55 wk gestation considered to be at increased risk for postoperative apnea; speaker uses spinal anesthesia in high-risk children

Oxygen toxicity: administration of oxygen unproven as primary cause of neoproliferation of retinal vessels; speaker avoids exposing babies to oxygen because of uncertainty

Neurotoxicity of anesthetics: sevoflurane shown to cause abnormal apoptosis and deposition of amyloid protein in brains of animals; Davidson et al compared children who received inhalational general anesthesia with children who did not and found no difference in cognitive testing at age 2 yr

Heart: sympathetic system attenuated in neonates; parasympathetic system dominant; heart rate high and stroke volume fixed; only ≈33% of total myocytes present at birth, so heart rate important; β-receptors immature

Congenital diaphragmatic hernia: bowel present in chest at time of birth; confounding factors include prematurity and associated clinical anomalies; scaphoid abdomen often present; hypoxic pulmonary vasoconstriction does not occur; oxygen saturation often low; types include herniation at foramen of Bochdalek (largest) and Morgagni hernia (anteromedial defect); lungs immature; compression leads to pulmonary hypertension mixed with normal pulmonary pressure; formation of muscle in diaphragm incomplete; treatment — early intubation required; decompress stomach to remove fluid from chest; avoid barotrauma and pneumothorax; protective ventilation — tolerate hypercarbia if oxygenation adequate; accept oxygen saturation of 85%; maintain low pressure; use high-frequency oscillation with nitric oxide for sicker babies; administer surfactant; reserve extracorporeal membrane oxygenation as last resort; anesthetic technique — depends on size of defect and respiratory status of baby; for small defects, attempt to extubate, use light narcotic, and avoid nitrous oxide; for larger defects, maintain intubation; multimodal therapies available for management of pain in children aged <1 yr; postoperative care — depends on level of pulmonary hypertension and amount of pulmonary hypoplasia; heart muscle mass and cavity attenuated

Omphalocele: during normal development, abdominal contents leave abdomen at age 5 to 10 wk and later return; with omphalocele, contents fail to return and become covered with membrane called amnion; amnion protects baby from loss of fluid and infection; umbilical cord located at apex of sac; associated anomalies include Beckwith-Wiedemann syndrome, mental retardation, hypoglycemia, congenital heart disease, large tongue, and intestinal atresia, stenosis, and malrotation; intubation often challenging; treatment — gradually attempt to return bowel to abdominal cavity; baby may not tolerate pressure in abdomen; babies usually intubated, so narcotics used to eliminate pain

Gastroschisis: occurs later during fetal development than formation of omphalocele; interruption of omphalomesenteric artery leads to ischemia and atrophy of abdominal wall; abdominal contents herniate through defect; umbilical cord located laterally; associated with few anomalies; bowel without membrane irritates uterine wall and may induce premature labor; treatment — typically, cesarean delivery; protection of bowel; speaker administers 20 mL/kg boluses of fluid (optimal amount unclear); avoid sodium chloride (resuscitative doses can cause hyperchloremic acidosis); hyperchloremia causes intense vasoconstriction in kidney; operative management — avoid nitrous oxide; use Foley catheter when possible to guide fluid management; place pulse oximeter on foot to monitor compression of aorta and iliac vessels; measure intragastric pressure; primary closure limited to gastric pressure <20 cm H2O; postoperative management — maintain intubation; pulmonary hypoplasia possible; surgical silo may alter lung; increased intra-abdominal pressure decreases flow of blood to kidneys, which triggers release of renin; activation of renin-angiotensin-aldosterone system common; monitor bowel and arterial pressure; if arterial line necessary, use smallest catheter possible

Tracheoesophageal fistula: 87% consist of blind upper esophageal pouch, with lower esophagus connecting to trachea; associated with anomalies (hepatobiliary anomalies most common); clinical signs include polyhydramnios, inability to place nasogastric tube, choking during feeding, aspiration pneumonia, and dehydration; gastrostomy performed only to protect pulmonary system; anesthetic management — use inhalational induction with spontaneous breathing; airway potentially challenging; intubate deep into one major bronchus, then pull back until both lungs moving; avoid ventilation of fistula; distance from carina to fistula very narrow

Meningomyelocele: caused by failure of neural tube to close during fourth week of gestation; usually identified by ultrasonography; involves meninges and neural components; highly associated with allergy to latex; risk for infection and dehydration high; place patient in prone position, with saline-soaked dressing; anesthetic management — intubate patient in lateral position or in supine position with mass supported in doughnut

Model for End-stage Liver Disease (MELD) score: child with biliary atresia will develop cirrhosis; some parents delay treatment so child’s condition worsens and rank on list for transplantation improves; MELD score in 30s indicates likelihood of death within weeks; 40s indicate urgent need for transplantation; 50s indicates ≈1 wk to live; postoperative analgesia — some children aged 3 days form memory of pain; treatment of pain essential; regional anesthesia beneficial (typically caudal or epidural); kits available for children aged 1 day or older; caudal dose 1 mL/kg, and lumbar dose 0.5 mL/kg; rate of failure 15%; bandages impregnated with antibiotics and narcotics effective; bupivacaine — speaker has observed seizures after use; toxicity more apparent than in adults, likely because dose excessive; intravenous infusion of lipid emulsion (Intralipid) — to avoid local anesthetic systemic toxicity (LAST), administer dose of 2 mL/kg

Readings

Anand KJ: Pharmacological approaches to the management of pain in the neonatal intensive care unit. J Perinatol 2007 May;27 Suppl 1:S4-S11; Broemling N et al: Anesthetic management of congenital tracheoesophageal fistula. Paediatr Anaesth 2011 Nov;21(11):1092-9; Davidson AJ et al: Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomised controlled trial. Lancet 2016 Jan 16;387(10015):239-50; Davis PJ et al: Smith’s Anesthesia for Infants and Children, Eighth Edition. Philadelphia: Mosby; 2011; Finnemore A et al: Physiology of the fetal and transitional circulation. Semin Fetal Neonatal Med 2015 Aug;20(4):210-6; Goonasekera C et al: Mortality following congenital diaphragmatic hernia repair: the role of anesthesia. Paediatr Anaesth 2016 Dec;26(12):1197-201; Mhamane R et al: Delayed primary repair of giant omphalocele: anesthesia challenges. Paediatr Anaesth 2012 Sep;22(9):935-6.

Disclosures

For this program, members of the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Scher was recorded at the 30th Annual Conference: Challenges for Clinicians, held December 2-4, 2016 in Chicago, IL, and presented by the University of Chicago, Department of Anesthesia and Critical Care. For information about upcoming CME opportunities presented by the University of Chicago, please visit cme.uchicago.edu. The Audio Digest Foundation thanks the speakers and sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

AN590801

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.