Neonatal Surgical Emergencies

Educational Objectives

The goal of this program is to improve awareness of the different types of neonatal surgical emergencies and the anesthetic management of these emergencies during. After implementing the program, the clinician will be better able to:

1. Identify 8 congenital anomalies that may present in newborns during surgery.
2. Discuss the recommended anesthetic procedure for each congenital anomaly in newborns.
3. Identify the recommended anesthetic drugs for newborns who present with a congenital anomaly.
4. Discuss the levels and management of dehydration in newborns.

Summary

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Introduction: will discuss 8 different congenital anomalies which may present in operating room (OR): congenital diaphragmatic hernia, tracheoesophageal fistula, lobar emphysema, necrotizing enterocolitis, omphalocele, gastroschisis, myelomeningocele, and pyloric stenosis

Congenital Diaphragmatic Hernia

Overview: defect in diaphragm; occurs about 7 to 10 weeks gestation while diaphragm is forming; 90% are Bochdalek hernia and most on left side; 9% of these hernias are called Morgagni hernias and occur in anterior region of diaphragm; only 1% are central defects; at this time in gestation, lungs, and possibly other organs in chest, are compressed by bowel; result is pulmonary hypoplasia and pulmonary hypertension (because blood vessels do not develop)

Associated anomalies: congenital heart defects occur in 20% to 40% of cases, chromosomal defects in about 10%, (specifically trisomy 13, 18, 12, 15 and DiGeorge syndrome), malrotation of gut in 40%, and genitourinary anomalies; one particular group of defects is known as Cantrell’s Pentalogy which is congenital diaphragmatic hernia with omphalocele, sternal cleft, ectopia cordis, and intracardiac defects, such as ventricular septal defect (VSD)

In utero surgery: from antenatal diagnosis; improves the ultimate clinical outcome; includes tracheal plugging and ex utero intrapartum treatment (EXIT procedure)

Primary physiology: extremely stunted lung growth with decreased alveoli and decreased type II cells; therefore, less surfactant in affected lung; pulmonary blood flow to affected lung is diminished due to hypoplasia of pulmonary vasculature; results in persistent fetal circulation and right-to-left shunting through patent foramen ovale (PFO); patent ductus arteriosis (PDA) may occur (particularly in early newborn period); 3 possible presentations

First presentation: severe respiratory distress associated with severe hypoplasia of lung; child presents with tachypnea, tachycardia, and cyanosis at birth; abdomen is scaphoid because most abdominal contents are actually in chest, most commonly left side; may be mediastinal shift due to mass effect

Second presentation: sudden deterioration in child’s status after honeymoon period and unrecognized presence of diaphragmatic hernia; key is correction of hypoxemia and pulmonary hypertension if identified and reversible

Third presentation: delayed onset with feeding difficulties, pneumonia, and bowel obstruction 24 hours later; associated with good prognosis

Survival: has increased dramatically; now about 75%; 80% if no extracorporeal membrane oxygenation (ECMO) is needed or other anomalies are present and child has normal birth weight and good Apgar scores; however, if anomalies are associated with diaphragmatic hernia, survival may only reach 20%

Lung management: use small tidal volumes, avoid overdistension of the hypoplastic lung (with worst complication being pneumothorax in good lung, which is potentially devastating), use of higher positive end-expiratory pressure (PEEP), and permissive hypercapnia; degree of pulmonary hypertension basically determines survival; if pulmonary vascular resistance normalizes within first 3 weeks or so after delivery, then child is likely to have good recovery; airway secured without mask ventilation; endotracheal tube inserted with intermittent mandatory ventilation after an IV induction with low airway pressures and PEEP

Anesthetics: muscle relaxants very effective in facilitating ventilation; primary anesthetic is opioids; high-dose opioids very effective in reducing stress response, reducing pulmonary hypertension, and preventing persistent fetal circulation during surgical stimulation; important to recognize that with return of chest contents to abdominal cavity, the abdominal cavity may be under increased pressure; pressure on the diaphragm reduces compliance of good lung; therefore, postoperative ventilation should be anticipated in these children; survival improved if infant stabilized for 24 to 72 hours before coming to OR, in contrast to previous surgical strategy where child is transferred directly from delivery room to OR

Optimization: optimize ventilation to maintain oxygenation and acceptable level of hypercapnia (whether intermittent mandatory ventilation, high-frequency oscillation, or even ECMO); optimize acid-base balance; if PCO₂ ≥ 60 millimeters of mercury (mmHg) and preductal saturation <70%, may decide to use high-frequency oscillation; if pulmonary hypertension is identified and not responsive to any therapeutic interventions, then nitric oxide should be considered; finally, once baseline ultrasound of head is performed, ECMO may be considered to stabilize child; surgical approach may be laparoscopic, thoracoscopic, or open in either case; thoracoscopic surgery generally avoided due to hypercapnia associated with insufflating CO₂ into chest (depends on child’s specific condition); fentanyl-paralysis approach is stress-free anesthetic; preferred, as inhalational agents may cause hypotension, but more importantly may not achieve desired concentration due to persistent fetal circulation and right-to-left shunting; avoid nitrous oxide; administer oxygen-air gas mixture with optimal ventilation at low peak pressures and PEEP; thermal regulation is critical in all neonates; forced air warming device should be used; if necessary warm room accordingly

Tracheoesophageal Fistula

Overview: defect usually diagnosed by inability to pass gastric tube at birth or, in some cases, due to feeding difficulties and aspiration pneumonia; associated anomalies, particularly esophageal atresia, occur in 30% to 50% of cases; anomalies associated with tracheoesophageal (TE) fistula include prematurity in 30% to 40%, congenital heart defect in 22% such as VSD, atrial septal defect (ASD), or Tetralogy of Fallot; other gastrointestinal abnormalities in 24%, such as duodenal or ileal atresia and malrotation, and genitourinary anomalies in 24%; up to 25% of children with TE fistula have 3 or more components of VACTERL (vertebral anomalies, imperforate anus, congenital heart disease, TE fistula, renal anomalies, and limb, specifically radial anomalies); before coming to surgery, imperative to perform echocardiogram as ASD-VSD combinations, such as atrioventricular canal and hypoplastic left heart syndrome, have been reported

Survival: depends on presence of congenital heart defect and birth weight; anticipate 95% to 98% survival for infant with TE fistula born >1500 grams (g) with no congenital heart defect; 60% to 80% survival when <1500 g or with major congenital heart defect; finally, 20% to 50% survival in infants born <1500 g and with major congenital heart defect

Defects: Type C most common defect in TE fistula; defined as proximal esophageal atresia and distal TE fistula; occurs in 80% of TE fistulas; second most common defect is proximal esophageal atresia with no connection between distal esophagus and tracheobronchial tree

Anesthesia: infants with TE fistula nursed in reverse Trendelenburg or lateral decubitus position before surgery; drain upper pouch by instilling oral or nasal gastric tube; surgery may be delayed in infants for the following: small for gestational age or preterm, pneumonia, sepsis, and other anomalies that require staging; when swallowed air or air that tracks across fistula occurs, gastric decompression may be required before surgical correction; central venous pressure (CVP), although used, rarely needed in full-term infants

Repairs: primary repair usually ideal approach; staged repair may be needed if gap between proximal and distal atretic pieces of esophagus is too large to bridge; increasingly, rigid bronchoscopy is performed to identify location of fistula and to confirm only one fistula (there was a case where two fistulas were present and not recognized before one of them was ligated)

Anesthetic management: several choices in TE fistula; either awake intubation with topical local anesthetic and light sedation or IV induction with propofol with or without muscle relaxant; finally, classic inhalation induction

Classic inhalation induction: traditionally, insert tracheal tube into right mainstem bronchus and withdraw it with bevel facing left to detect left lung ventilation; tape immediately when left chest auscultation is positive; then, turn bevel anterior to prevent ventilation of fistula — verifyied fiberoptically; gentle ventilation may be assisted until chest open and stomach confirmed not to be inflating; if stomach begins to inflate, then open chest and suture immediately across fistula to prevent further occurrences; oxygen saturation indicates whether tube is endobronchial at any point; presence of end-tidal CO₂ will confirm adequacy of ventilation

Endotracheal tube: important to secure endotracheal tube so not displaced; again, if gastric inflation occurs, block fistula usually with ligature to fistula; in some cases, if inflation occurs and compromises ventilation, endotracheal tube taping can be undone and advanced into right long to stop gastric inflation until ventilation managed; if concern preoperatively that gastric inflation is likely to occur, Fogarty catheter may be inserted, followed with fiberoptic bronchoscopy into left lung, inflated to prevent stomach inflation (this depends on level of fistula between trachea and esophagus); after ligation of fistula, lung should be recruited, particularly to ensure that there is bilateral air entry and that correct tissue was ligated with ligature; surgeons often request endotracheal tube be removed at end of surgery; perioperative analgesia may be confirmed with either caudal epidural catheter or local infiltration of intercostal nerves on side of surgery

Neonatal Lobar Emphysema

Overview: rare defect usually involves upper or middle lobes of left lung; associated with congenital heart disease in about 35% of cases and appears on x-ray as hyperaerated portion of lungs; rule out other defects before confirming diagnosis; gastric tube should be inserted and child nursed upright; all of the following may occur if emphysema greatly distends lung — progressive respiratory failure, unilateral expansion of thorax, atelectasis of contralateral lung, and mediastinal shift

Management: may require bronchoscopy with oxygen, atropine and sevoflurane; after diagnosis is confirmed, secure airway for surgery either with inhalation induction or awake; avoid nitrous oxide in all cases; maintain spontaneous respiration to avoid overdistension of affected lung or, at least, support ventilation and tolerate permissive hypercapnia until sections of lung isolated; alternately, if lobar emphysema appears to expand and present ventilation problem, endobronchial intubation of contralateral lung or use of endobronchial blocker in left lung may isolate lung lesion until removal; when chest is open and lobe isolated, add positive pressure ventilation

Necrotizing Enterocolitis

Overview: infectious complication occuring in 90% of cases in premature newborns; occurs sporadically and incidence common in premature infants <750 g; mortality not insignificant, ranging from 20% to 50%, and if surgeons must be involved, mortality closer to 50%; occurs in post-birth asphyxia with respiratory distress syndrome and in newborns born in shock

Pathophysiology: intestinal mucosal injury usually at site of defect in ileocolic region; occurs secondary to bowel ischemia; perforation and peritonitis may ensue; child may become extremely ill, septic with fluid and electrolyte disorder, endotoxic, and with coagulopathy secondary to thrombocytopenia; mucosal injury likely result of reduced mesenteric blood flow with fetal asphyxia, PDA ligation, heart failure, arrhythmia, cardiorespiratory distress, or hypoxemia

Three stages: stage I is apnea, bradycardia, lethargy, abdominal distention and vomiting; stage II, features of stage I plus pneumatosis intestinalis, which is seen on x-ray; stage III, features from stages I and II and repeated bradycardia, hypotension, acidosis, disseminated intravascular coagulation (DIC), and anuria

Treatment: supportive — nothing by mouth, decompress bowels, aggressively manage fluids, administer blood for anemia and coagulation problems, possibly total parenteral nutrition (TPN), and possibly antibiotics for any known or potential infections; surgery indicated for bowel perforations in stages II and III; be sure to appreciate needs of premature child — a septic and acidotic child in shock or coagulopathy — and aggressively administer inotropes and blood products

Anesthesia: appropriate treatment for premature infant with blood products including platelets; management of sepsis and hypotension with antibiotics, dopamine, and possibly epinephrine infusions

Surgery: when required, patients quite unstable (possibly already on high frequency ventilation to oxygenate and clear CO₂); therefore, surgery often occurs in Neonatal Intensive Care Unit (NICU); newborns are preterm; correctly placed tube confirmed with chest x-ray; goal is to provide adequate surgical conditions by providing dose of opioid to block stress response and paralyze infant; 10 to 15 mcg/kg intravenous (IV) fentanyl should be sufficient in child with raised intraabdominal pressure to maintain stable vital signs once child adequately resuscitated; need IV access and, if necessary, arterial blood gases to confirm adequacy of oxygenation, ventilation; before opening abdomen, warm fluids; blood, calcium (if a massive transfusion is needed), coagulation factors, and platelets should be on hand; greatest impact of surgery on child’s vital signs with opening of abdomen; after that challenge has been met, then remainder of anesthetic fairly straightforward

Omphalocele and Gastroschisis

Overview: anterior abdominal wall defects; occur sporadically, not genetically or ethnically related; detected on ultrasound as early as 10 to 14 weeks gestation; abdominal contents — small and large bowel, stomach, and possibly liver (in 1/3 or more of cases) — herniate through anterior abdominal wall possibly into 4 to 12 cm sack; in omphalocele, umbilical cord continues with apex of sack

Anomalies of omphalocele: 50% to 75% have associated anomalies: 30% have chromosomal defects, 30% premature, 25% malrotation and other gastrointestinal (GI) anomalies, and 10% congenital heart disease; most common syndrome is Beckwith-Wiedemann syndrome (includes triad of omphalocele, macroglossia and hypoglycemia); other defects include prune belly syndrome and trisomy 13, 15, 18, and 21; another interesting association is Cantrell’s Pentalogy (associated with sternal abnormalities, diaphragmatic hernia, ectopic and anomalous heart and gene defects on the X, 25-26 chromosome)

Gastroschisis: distinct from omphalocele — defect to right of umbilicus and much smaller, about 2 to 5 cm; herniated bowel (usually, but sometimes other abdominal contents may follow) not covered with any sack or in any fluid; results in bowel becoming twisted or dried out; may be loss of fluid, and loss of heat; may lead to more serious feeding and absorption problems than in omphalocele; suggested that gastroschisis may result from in utero exposure to acetaminophen, aspirin, and/or pseudoephedrine taken by mother

Management of omphalocele and gastroschisis: depends on size of defect; primary closure is preferable, reduces risk of infection and GI dysfunction, particularly with gastroschisis; however, returning large herniated abdominal contents to small abdomen may raise intra-abdominal pressure, such that peak inspiratory pressure is excessive; venous return, cardiac output, and renal function are compromised; therefore, transduce either intragastric pressure or central venous pressure as metric to determine whether primary repair and return of abdominal contents can be undertaken in one step; if peak pressure, measured by either contractile deceleration point (CDP) or intragastric pressure, is transduced <20 mmHg, then child likely will tolerate primary repair; if not, secondary closure may be undertaken — involves application of silo pouch, followed by staged reduction in pouch until abdominal contents accommodated without compromising perfusion and ventilation

Large defects: may be painted with sulfadiazine compound and left to epithelialize over weeks or months (possibly unable to return to abdominal cavity, particularly if child is extremely premature)

Management of child: includes adequate hydration, balanced salt solution, monitoring intragastric pressure during repair, ensuring adequate ventilation and oxygenation, glucose level, and temperature control; infants with gastroschisis almost always receive TPN in preoperative period — important to maintain glucose component of TPN during surgery to avoid accidental occurrence of hypoglycemia

Myelomeningocele

Overview: open neural tube defect containing spinal cord and other neural tissue, dura, and some paravertebral tissue; if spinal cord not included, simple meningocele; associated with folic acid deficiency; to lessen occurrence, women who anticipate becoming pregnant should begin folic acid before planned conception; aggressive use of multivitamins and folic acid during preconception period has reduced frequency of myelomeningocele in the population; defect is failure of neural tube to close and occurs about 4 weeks gestation (reason why folic acid preventative management strategy should begin before conception)

Diagnosis: antenatal diagnosis of neural tube defect confirmed with serum alpha-fetoprotein test; ultrasound confirms defect

Associations: can be with hydrocephalus, Chiari malformation, possible agenesis of corpus callosum, abnormal cerebral gyrations, and vertebral anomalies; in most cases, lesion in lumbar region, but may occur farther up in spinal column

Clinical manifestations: include paralysis of lower extremities, sensory loss, bladder and bowel dysfunction, and hydrocephalus

Surgery: before surgery, infants nursed in prone position to protect neural tissue; generally, close defects surgically within 48 hours of birth to minimize infection risk; infants present with IV in place; airway may be secured with IV induction either in left lateral decubitus position or supine position with padding around defect and spine to protect from compression; if defect in lumbar region, regular oral endotracheal tube may be used; if defect in thoracic or occipital region, then nasotracheal tube or reinforced tube may be required due to unusual position for surgery; once airway secured, place child in prone position and support chest to ensure free abdomen and easy ventilation; if small defect, often closed directly once neural tissue freed; in contrast, large defect may require plastic surgery to perform rotational flap in skin to cover defect; in most cases, blood not required for this surgery

Anesthesia: consists of general endotracheal anesthesia, inhalational agent, and small dose of opioids (many infants do not have sensation at and below myelomeningocele)

Pyloric Stenosis

Overview: usually occurs in firstborn males (male-to-female sex ratio of 5:1), white more commonly than black infants, and may be associated with smoking by mother; infants often 2 to 7 weeks of age and may be preterm; substantial hypertrophy of muscularis pyloric layer with palpable olive-shaped mass in right-upper quadrant (also demonstrable on ultrasound); child suddenly vomits in projectile manner (note — not simply spitting up, but vomiting that travels for several inches out of child’s mouth) and associated with dehydration and loss of hydrochloric acid, hydrogen ions from stomach, sodium, and chloride; results in hypochloremic metabolic alkalosis; acid-base disturbance depends on how long vomiting continued before child was brought for medical evaluation; due to persistent vomiting, kidneys produce aldosterone, retain sodium, and expel potassium and hydrogen ions in urine (may lead to paradoxical aciduria); with persistent vomiting and inadequate care, dehydration may ensue and metabolic acidosis develop

Levels of dehydration: in infancy, 3 levels (mild, moderate, or severe) of dehydration reflected by amount of body weight lost; mild state refers to 5% loss in body weight (about 50 cc/kg) with poor skin turgor and dry mouth; moderate state refers to 10% loss in body weight with poor skin turgor and dry mouth, and also includes tachycardia, sunken fontanelle, and oliguria; severe state refers to about 15% loss in body weight loss (150 cc/kg) with all listed previous signs as well as sunken eyes, hypotension, and anuria

Management: not surgical emergency, but medical emergency with resuscitation of child for dehydration and electrolyte imbalance; resuscitation takes 24 to 48 hours to achieve normal fluid and electrolyte concentrations; however, trigger point for referring to surgery by pediatricians and primary care providers has resulted in shortened interval of vomiting; many enter hospital minimally dehydrated and with normal electrolytes; for surgery — if normal fluid and electrolyte concentrations and fluid resuscitated — administer atropine, then insert orogastric tube and suction stomach in supine position, left decubitus position, and right decubitus position; note — high amount of fluid can accumulate in child who recently had or still has standard orogastric tube in place; give child 20 mL/kg boluses of balanced salt solution if any evidence of dehydration until fluid resuscitation achieved; once urine output continues, potassium may be resumed in IV; when electrolytes and glucose concentrations are normal in bloodstream, child may proceed for surgery; criteria for proceeding based on the electrolytes: chloride of >88 mEq/L, potassium >3.2 mEq/L, sodium >132 mEq/L, and bicarbonate <30 mEq/L (to ensure no metabolic alkalotic state from chronic vomiting); fluid status should reflect normal vital signs and urine output of 1-2 mL/kg/hr; reminder — reinsert or insert orogastric tube and empty stomach after IV atropine, preoxygenate child, and then perform modified rapid sequence induction with propofol and muscle relaxant

Muscle relaxant: choice depends on situation; in females, use succinylcholine due to rarity of undiagnosed myopathies and hypotonia; alternately, use rocuronium or cisatracurium, which spontaneously degrades, recognizing that sugammadex reverses muscle relaxants; many surgeons complete pyloromyotomy in about 20 minutes and very difficult to reverse large dose of rocuronium in that time period

Opioid: alternately, give very small dose of opioid and large dose of propofol to intubate without muscle relaxant; associated problems are that opioid may delay emergence, as children often have very little pain after surgery

Surgery: routinely use desflurane as maintenance inhalational agent because it has most rapid pharmacokinetics in terms of washout; avoid cricoid pressure in infants because force of only 15 Newton of force may distort cricoid ring and make intubation difficult; once tube is placed, ventilate lungs and use 60% nitrous oxide and desflurane for open pyloromyotomy; after performing pyloromyotomy, surgeons often request insufflation of air into orogastric tube to distend stomach and test for leak; managed by using 60 cc syringe or 40 cc syringe and stopcock attached to end of orogastric tube; again, very little pain after open or laparoscopically conducted surgery

Perioperative: acetaminophen usually sufficient for perioperative pain management; in completely awake infants, extubate in recovery position and continue IV balanced salt solution until infant tolerant of oral feeds and ready for release from hospital

Readings

Becke K et al: Choosing wisely in pediatric anesthesia: an interpretation from the German Scientific Working Group of Paediatric Anaesthesia (WAKKA). Paediatr Anaesth 2018;28(7):588-96; Bojanic K et al: Congenital diaphragmatic hernia: outcomes of neonates treated at Mayo Clinic with and without extracorporeal membrane oxygenation. Paediatr Anaesth 2017;27(3):314-21; Oakes M et al: Advances in prenatal and perinatal diagnosis and management of gastroschisis. Semin Pediatr Surg2018;27(5):289-99; Rogers IM: Pyloric stenosis of infancy-the anaesthetic challenge. J Clin Anesth Manag 2017;2(1). doi:10.16966/2470-9956.124; Zani A et al: Intraoperative acidosis and hypercapnia during thoracoscopic repair of congenital diaphragmatic hernia and esophageal atresia/tracheoesophageal fistula. Paediatr Anaesth 2017;27(8):841-8.

Disclosures

For this activity, the faculty and planning committee reported nothing to disclose.

Acknowledgements

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:

ANBR190151

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.