Case 59 - abdominal wall defects Flashcards
What is the difference between an omphalocele and gastroschisis?
Omphalocele
Etiology
- failure of gut migration from yolk sac to abdominal cavity (in early fetal life)
- yolk sac = umbilical vesicle is a membranous sac attached to an embryo
Location
- base of umbilial cord
- covered by peritoneum, bowel is morphologically and functionally normal
Associated diseases
- assoc with congenital anomalies: cardiac, craniofacial, urologic defects
- Beckwith-Wiedemann syndrome = macroglossia, hypoglycemia, mental retardation
What is the difference between an omphalocele and gastroschisis?
gastroschisis
Etiology
- occlusion of omphalomesenteric aretery –> leads to atrophy of abdominal wall
Location
- to the right of umbilicus
-
no peritoneal covering
- risk of infection and extracellular fluid loss 2/2 evaporation
- abdominal viscera herniated
- bowel -> edematous, inflammed, functionally ABNORMAL
- medical emergency
associated disease
- no congenital anomalies associated with it
What are pre-op concerns for these two defects?
1) Pre-op goals
- exposed viscera –> reduce fluid losses, prevent infection, hypothermia, and trauma
- warm moistened sterile dressing to exposed viscera, isolate defect with sterile clear plastic bag (minimize temp and fluid losses)
2) congenital anomalies
* look for cardiac and urologic problems (ophalocele)
3) IV access
- aertial line - blood sampling
- CVC - fluid management and rapid fluid bolus
- consier albumin for intravasc volume expansion (crystalloid can lead to further gut edema)
4) electorlyte
- replete electrolyte
- correct electrolyte and dehydration pre-op
how would you induce a neonate with abdominal wall defect?
1) Warm OR room, place forced air warming blanked on OR table
* prevent temprature and fluid loss 2/2 evaporation
2) place standard ASA monitors
3) awake gastric decompression
- pre-treat with atropine
- prevent distension and aspiratoin
4) prepare for RSI with cricoid pressure
- IV induction agent - prop vs etom depending on volume status
-
pre-treat with atropine (immature sympathetic system)
- bradycarida during suctioning, laryngoscopy, intubation, Sux admin, and hypoxia
- muscle relaxant
- Sux vs Roc
5) intubate
- miller 0 or 1 blade, 3.0 cuffed tube
- air leak of 20-30 ch H2o is desirable
after you induce the neonate with an abdominal wall defect, how will you manage the anesthsia?
1) maintaineance anesthesia
- volatile or IV agents (propofol)
- Avoid N2O - can diffuse into intestine and dilate bowel (2/2 nitrogen failing to enter circulation)
2) muscle relaxation
* required for surgery –> allows for surgical closure of defect
3) Normovolemia
- fluid losses = mainteance, replace third space losses, replace blood loss
- maintenance = 4+2+1 method
- third space loss = at least 8 - 15 mL/kg/hr
4) Blood loss
- 3:1 crystalloid to each mL of blood loss
- 1:1 transfuse 1 mL of blood for each mL of blood loss
5) frequent assessment of volume status
* UOP, vital signs, frequet lab draws, clinical exam
How do you calculate maximum allowable blood loss?
MABL = [(HcTs - HcTl) / HcTs] x EBV
EBV
- pre term - 100 ml/kg
- full term - 90 ml/kg
- infant - 80 ml/kg
Is the surgical treatment for gastroschisi and omphalocele important for post-op concerns?
- surgical tx is either primary or staged closure
Primary closure
- small repair –> possible extubation at end
- large repair + primary closure -> remain intubated and mech vent post-op. Allow tissues to heal
-
Tight primary closure
- associated with increased intraabdominal pressure (> 20 mmHg)
- increase peak airway pressure
- decrease kidney perfusion –> dec UOP
- compression of IVC = dec venous return = dec BP
Staged closure
- prosthetic silo over exposed viscera.
- reduce viscera into abdominal cavity every 2-3 days so abdominal cavity can accomodate it without increasing intraabdominal pressure
- once viscera is reduced, neonate brought to OR for closure of abdominal defect
