1. discuss the underlying pathophysiology of selected neonatal emergencies, 2. explain the anesthetic implications and 3. describe safe anesthetic plans for each.
Preoperative Evaluation
• Maternal and perinatal history
• Recreational drug use
• Birth history
• Minimum labs: glucose and CBC • Look for associated anomalies
• Cardiac and respiratory status
• Metabolic and electrolyte imbalance • Hydration status • Coagulation profile • IV access
Pyloric Stenosis
Pyloric Stenosis
Most common GI obstructive anomaly in neonates
Hypertrophy of the muscular layer of the pylorus
A medical emergency but not a true surgical emergency Incidence: 1 – 3 :1,000 live births 2 - 5x more common in first born, M > F (4:1)
Pyloric Stenosis
Etiology : unknown
? acquired condition with hereditary
predisposition Symptoms are apparent between 2nd-6th wk of life
Presents with nonbilious projectile vomiting, signs of dehydration, jaundice (2%)
Pyloric Stenosis
Physical Exam visible gastric peristalsis palpable “olive-shaped” mass to the right of the epigastric area signs of dehydration
Labs: CBC ABG
serum electrolytes BUN
EKG
Pyloric Stenosis
Diagnosis
history and physical exam abdominal ultrasound upper GI series with barium contrast not recommended pathological pyloric wall thickness ≥ 4 mm pyloric length of > 16 cm
20 - 40 mEq/L
replacement: LR, albumin, normal saline
• Correction of electrolyte imbalance
• Prevention of aspiration : NGT
Pyloric Stenosis
Surgical Management Pyloromyotomy definitive treatment open or laparoscopic Lab indices for safe anesthesia serum Cl >100 mEq/L HCO3 < 28 mEq/L
Pyloric Stenosis
Anesthetic Concerns • pulmonary aspiration • severe dehydration
• metabolic alkalosis
Pyloric Stenosis
Intraoperative Management
Monitors : ASA standard
Decompress the stomach
GA: Induction: controversial awake intubation rapid sequence IV induction and intubation with cricoid pressure inhalation induction with cricoid pressure ± muscle relaxant
Pyloric Stenosis Intraoperative Management
Cook-Sather, 1998 (CHOP)
• prospective, nonrandomized study • awake vs paralyzed intubation (RSI and MRSI) • faster and more successful tracheal intubation with muscle paralysis • awake intubation does not protect from bradycardia and desaturation
Pyloric Stenosis
Intraoperative Management
Maintenance
IV narcotics: rarely needed inhalational agents
Postop pain relief
acetaminophen 30-40 mg/kg PR caudal epidural LA infiltration of surgical incision
Congenital Diaphragmatic Hernia
a problem unresolved
Congenital Diaphragmatic Hernia
Herniation of abdominal viscera into the thorax Result from failure of the pleuroperitoneal canal to close at ~ 8th wk of gestation or early
return of midgut to the peritoneal cavity
Most challenging and frustrating of all neonatal surgical emergencies
Congenital Diaphragmatic Hernia 50% mortality regardless of the method of treatment Incidence: 1:2,000-5,000 live births
M<F 1:1.8, frequently full term
Etiology: unknown no genetic factors have been implicated Antenatal history: polyhydramnios
• Postductal SpO2 ignored unless pH is
< 7.20 or pCO2 > 65
Congenital Diaphragmatic Hernia Bohn (1986) reevaluation of the traditional “mad dash” surgical strategy
recommended 24 – 48 hrs medical stabilization
assessment of efficacy of delayed approach
infants unresponsive to initial therapy will fail to survive with surgery or any other treatment including ECMO
Congenital Diaphragmatic Hernia
The Relationship Between PaCO2 and Ventilation Parameters in Predicting Survival in CHD • Arterial CO2 accurately reflects the degree of lung development
• Poor survival in the presence of severe pulmonary hypoplasia
• CO2 retention and severe preductal shunting have 90% mortality
Bohn, DJ, et al J of Pedia Surg 19: 666-671, 1884
Congenital Diaphragmatic Hernia
nomogram: to predict the degree of pulmonary hypoplasia in the infants and chance of survival used the preop PaCO2 and an index of ventilation (Vi) If PaCO2 < 40 and Vi < 1000: survival almost universal If PaCO2 > 40 and Vi > 1000: death virtually inevitable ٭Vi = mean airway pressure x respiratory rate
Congenital Diaphragmatic Hernia
Relationship of Alveolar-arterial Oxygen Tension Difference in Diaphragmatic Hernia in the Newborn
A-aDO2 on 100% O2 < 400 mmHg: usually survive 400 - 500 mmHg: intermediate chance > 500 mmHg: unlikely to survive
Harrington J, et al Anesthesiology 56: 473-476, 1982
Congenital Diaphragmatic Hernia
Acid Base Balance and Blood Gases in Prognosis and Therapy of CHD High Mortality pH < 7.0 pCO2 >60 mmHg pO2 < 50 mmHg
Boix-Ochoa J, et al J Pediatric Surg 9:49-57, 1974
Congenital Diaphragmatic Hernia
Indications of Surgical Repair • Reversal of ductal shunting • O2 index of < 40 • Arterial pCO2 maintainable under 40 mmHg • Hemodynamic stability
Congenital Diaphragmatic Hernia
Preoperative Preparation
• Look for associated anomalies
• Labs: CBC, electrolytes, ABG, glucose,
blood type and crossmatch
Intraoperative Management Monitors: ASA standard invasive : arterial line ± CVP foley catheter * 2 pulse oximeters: preductal and postductal
* precordial stethoscope on the right axilla
NGT to decompress the stomach Adequate IV access
Congenital Diaphragmatic Hernia
Intraoperative Management Induction awake intubation rapid sequence IV induction and intubation with assisted or controlled ventilation * avoid mask ventilation or PPV before intubation Supine position, left subcostal incision
Congenital Diaphragmatic Hernia
Intraoperative
Maintenance of anesthesia
volatile agents + IV narcotics + muscle relaxants
TIVA avoid nitrous oxide avoid increase in PVR leading to R→L shunting: hypoxia, acidosis, hypothermia, pain
treat metabolic acidosis
replace significant blood loss
Postoperative Care
Ventilatory support Close fluid management Hemodynamic monitoring
“Honeymoon Period” followed by deterioration
increase abdominal pressure
impaired peripheral and visceral perfusion
limited diaphragmatic excursion worsening of pulmonary compliance
Congenital Diaphragmatic Hernia
Management of PPHN
• Minimize ETT suctioning • Vasodilators : rarely effective
tolazoline nitroglycerin isoproterenol SNP PGE1
• Inhaled nitric oxide
endothelium - derived relaxing factor (EDRF) selective pulmonary vasodilation rapidly metabolized has not been shown to improve survival
Congenital Diaphragmatic Hernia
Extracorporeal Membrane Oxygenation (ECMO) • Use: controversial • Allows the lungs to develop & restructure • Expensive • improved survival in neonates with > 80% mortality
Congenital Diaphragmatic Hernia
Criteria for ECMO • Gestational age ≥ 34 wks • Reversible disease process present • Weight ≥ 2000 grams • Predicted mortality ≥ 80% estimated by oxygenation index of > 40
FiO2 x mean airway pressure x 100
PaO2
Congenital Diaphragmatic Hernia
Contraindications
Gestational age < 34 wks Weight < 2000 grams Preexisting intracranial hemorrhage (≥ grade II) Aggressive respiratory treatment > 1 wk Congenital heart disease Congenital or neurological abnormality incompatible with good outcome
TracheoEsophageal Fistula (TEF)
Tracheoesophageal Fistula
Incidence: 1:4000 live births
M > F (25:3) 10-40% are preterm
Antenatal history: polyhydramnios (60%)
Etiology: failure in mesenchymal separation of upper foregut
Preoperative Preparation 24-48 hr medical stabilization Antibiotics: ampicillin and gentamicin Ensure availability of blood in the OR Optimize volume status and metabolic state Intubation preferably in the operating room under controlled situation
Tracheoesophageal Fistula
Intraoperative Management
Main Concern
oxygenation and ventilation
securing the airway
Monitors
ASA standard
± invasive : arterial line
* precordial stethoscope in the L axillary area
Tracheoesophageal Fistula
Intraoperative Management
Anesthetic Technique • “classic approach”
GA without muscle paralysis
• combined light GA + epidural (Bosenberg)
• GA with muscle paralysis
Tracheoesophageal Fistula
Intraoperative Management
Induction • awake intubation • rapid sequence IV induction • inhalation induction spontaneous ventilation without muscle relaxant
Tracheoesophageal Fistula
Intraoperative Management
Assessment of ETT position
Goal: ETT just above the carina and just below the fistula • Right mainstem intubation and withdraw ETT until bilateral breath sounds • Left mainstem intubation: poorly tolerated due to insufficient pulmonary reserve
Tracheoesophageal Fistula Intraoperative Management • If g-tube present, place end of g-tube under water seal: ETT above fistula → (+) bubbles
• Connect capnograph to
g-tube: (+) ETCO2 if ETT above the fistula • ? rigid bronchoscopy - not proven
Tracheoesophageal Fistula
Intraoperative Management
Berry FA, Anesthetic Management of Difficult and Routine Pediatric Patients, 2nd Ed. 1990
Tracheoesophageal Fistula
Intraoperative Management
Beware of gastric distention
gentle positive pressure ventilation
gastrostomy: open if present
TEF + RDS combination
now what???!!
gastrostomy under local anesthesia fogarty embolectomy catheter
Tracheoesophageal Fistula
Intraoperative Management
Lateral decubitus position Posterolateral thoracotomy Maintenance of Anesthesia Narcotic technique Inhalation technique + regional anesthesia ? Use of nitrous oxide
Tracheoesophageal Fistula
Intraoperative Management
Surgical repair
• ligation of fistula
check air leak in suture line • esophageal repair identify the pouch placement of feeding tube • chest tube placement and closure of thoracic cavity
Tracheoesophageal Fistula
Intraoperative Management
Intraoperative problems • Endobronchial intubation • Intubation of fistula • Obstruction of ETT
• V/Q mismatch
lateral decubitus position
nondependent lung retraction
• Vagal response to tracheal manipulation • Return to transitional circulation and shunting
Tracheoesophageal Fistula
Postoperative Management
Early extubation desirable
caution: disruption of surgical repair with
reintubation Postop Pain Management 1. IV narcotics 2. epidural infusion: 0.1% bupivacaine + fentanyl 0.5 mcg/ml at 01.-0.2 ml/kg/hr 3. rectal Tylenol + LA infiltration of incision
Tracheoesophageal Fistula
Main Cause of Mortality associated anomalies
survival rates 85-90% Long Term Complications
GE reflux
anastomotic stricture
tracheomalacia
Abdominal Wall Defects
Gastroschisis
Omphalocoele
Gastroschisis Greek word for “belly cleft” Evisceration of gut through a 2-3 cm defect in the anterior abdominal wall lateral to the umbilicus, usually on the right
Absence of covering or sac
chemical peritonitis infection
ECF loss
heat loss
Incidence: 1:15,000-30,000 live births
Gastroschisis
Gastroschisis
Etiology
exact cause unknown Theories • intrauterine occlusion of omphalomesenteric artery → ischemia and atrophy of abdominal muscles • early fetal rupture of an omphalocoele
Gastroschisis
• rupture of umbilical cord at the site
of the resorbed right umbilical vein
• ? Maternal: smoking, ETOH,
Omphalocoele
External herniation of abdominal viscera into the base of the umbilical cord through a central defect Defect: small or large Umbilical cord is inserted into the apex of the lesion Presence of covering or sac (amnion and peritoneum) Incidence: 1-5,000-10,000 live births
Omphalocoele
Omphalocoele
Etiology
• incomplete return of the gut to the abdominal cavity due to an abdominal lateral fold defect • Failure of migration and fusion of cranial, caudal and/or lateral folds of the embryonic disc at ~ 3rd wk of gestation
Omphalocoele
Cranial Fold : Pentalogy of Cantrell Epigastric omphalocoele Sternum cleft
• Heat loss : neutral thermal environment • Difficulties of surgical closure • Associated congenital anomalies & prematurity
Abdominal Wall Defects
Preoperative Management
• Infection and postop nutrition • Postoperative ventilation • Airway • Metabolic status
• Aspiration precautions
• Direct trauma to herniated organ
Abdominal Wall Defects
Preoperative Management
Lab workup CBC Electrolytes and Glucose ABG
Ancillary Procedures
CXR
Echocardiography
Abdominal Wall Defects
Intraoperative Management Premedication: ± atropine IV access: 2 large bore IVs preferably above the diaphragm Monitors: ASA standard : 2 pulse oximeters
invasive: arterial line
± CVP foley catheter intraop airway pressures
Abdominal Wall Defects
Intraoperative Management
Choice of Anesthesia
general anesthesia spinal (reported) in selected patients
Induction
decompress the stomach rapid sequence IV induction with cricoid pressure or inhalation induction and intubation or awake intubation
Abdominal Wall Defects
Intraoperative Management
Maintenance of Anesthesia
• Opiate technique or judicious use of
inhalational agents • Avoid nitrous oxide • Adjust FiO2: PaO2 50-70 mmHg SpO2 97-98% term
Staged Reduction
• Dacron reinforced silastic silo
• Gradual reduction over 1- 2 weeks • Ketamine or opioid ± muscle relaxant in intubated patients or • Titration of ketamine 0.5 -1 mg/kg IV with spontaneous breathing unintubated infants • Final closure in the OR
Abdominal Wall Defects Intraoperative Management
Silo closure
Abdominal Wall Defects
Intraoperative Management
To extubate or not to extubate?
• Size of patient
• Intraoperative events • Prematurity • Associated pathology • Hemodynamic status • Magnitude of the abdominal defect • Type of repair
Abdominal Wall Defects
Postoperative Management
NICU Postop ventilation in most neonates for 24-48 hrs Fluid requirements may remain high Prolonged postop ileus: TPN or PPN
Prevent infection: higher with silo
Watch for circulatory compromise cyanotic lower limbs Postop HTN due to ↓ renal perfusion and activation of renin-angiotensin-aldosterone
Abdominal Wall Defects
Early Postoperative Complications
• Necrotizing enterocolitis
• Renal insufficiency
• Pneumonia
• Abdominal wall breakdown
• PDA
• GE reflux
Necrotizing Enterocolitis (NEC)
Necrotizing Enterocolitis (NEC)
Life-threatening intestinal inflammation or injury Caused by bacterial invasion of previously
injured or ischemic bowel wall
Incidence: 5 -10% in infants <1500g birth
weight
Mortality rate: 10 - 30%
Necrotizing Enterocolitis (NEC)
Single most important factor
PREMATURITY
Can occur in:
premature infants
LBW infants
Full term infants
fed and unfed infants
Necrotizing Enterocolitis (NEC)
Other factors ischemia bacterial infection GI endotoxemia
enteral feeding
use of hyperosmolar formula congenital heart disease hx of umbilical arterial catheterization hx of exchange transfusion
Necrotizing Enterocolitis (NEC)
Early signs
↑ gastric residuals with feedings temperature instability poor feeding bilious vomiting lethargy
mucoid or bloody stool
apnea and bradycardia
Necrotizing Enterocolitis
Late Signs Hemodynamic instability Anemia
Thrombocytopenia
Coagulopathy, DIC
Prerenal azotemia
Metabolic acidosis
Necrotizing Enterocolitis (NEC)
Physical Exam distended and tender abdomen Labs: CBC electrolytes and glucose platelets and coagulation profile
DIC profile
ABG
Necrotizing Enterocolitis (NEC)
Abdominal X-ray
• signs of bowel obstruction • ileus with edematous bowel
• Pneumatosis intestinalis
or intramural air (arrow)
• portal vein air
• pneumoperitoneum
Necrotizing Enterocolitis (NEC)
Medical Management
initial treatment, for 7-10 days
75% successful Surgical Treatment
10 - 50% mortality
Necrotizing Enterocolitis (NEC)
Medical Management
• No enteral feedings for 10-14 days • NGT on intermittent suction • Hydration and correction of electrolytes • Ventilatory support • Antibiotics • Blood and platelet transfusion if needed
Summary
• Almost all neonatal surgical “emergencies” are really “urgencies”
• Immaturity of organ system in neonates
alters pharmacology and physiology • Thorough preop assessment is required in all neonates • One anomaly mandates a search for others
• Murmurs necessitate a cardiology consult
• Successful perioperative outcome depends on open communication and teamwork between neonatologist, anesthesiologist and surgeon • Initial resuscitation of neonatal surgical candidates includes:
airway protection adequate IV access fluid resuscitation temperature stabilization gastric decompression administration of antibiotics identify associated anomalies
Omphalocoele
Embryology Failure of the midgut to return to the abdominal cavity by the 10th wk of gestation