Pyloric Stenosis
26/12/10
FANZCA Part II Notes
CK Notes
OHOA page 796
Pyloric Stenosis is a medial emergency that requires urgent fluid resuscitation and resolution
of biochemical abnormalities. Definitive surgical treatment can then be undertaken to restore
enteral nutrition.
CLINICAL FEATURES
-
commoner in first born males
80% males
10% are premature
projectile vomiting in neonate (not billous)
2-8 weeks
dehydration
weight loss
hyperaldosteronism with paradoxical aciduria
visible peristalsis and olive sized mass in epigastrium
confirmed on US
associated pathology: cleft palate, GORD
PATHOPHYSIOLOGY AND BIOCHEMISTRY
- develops:
1.
2.
3.
4.
5.
6.
hypochloraemia
metabolic alkalosis
hyponatraemia
hypokalaemia
initially, alkaline urine -> later, acidic urine
dehydration
HYPOCHLORAEMIA
- loss of chloride in vomitus
METABOLIC ALKALOSIS
- loss of H+ in vomitus
- decreased secretion of pancreatic HCO3- increased HCO3- presented to distal tubule and eliminated producing an alkaline urine
HYPONATRAEMIA
- loss of Na+ in vomitus
- decreased absorption of Na+
Jeremy Fernando (2010)
- loss of Na+ in urine until kidney adjusts to increased HCO3- load
- activation of rennin-AG-ALD system to off set this and restore Na+ and H2O
HYPOKALAEMIA
- K+ loss in vomitus
- activation of rennin-AG-ALD system with produces loss of K+ in urine
- with extreme K+ loss in urine -> it gets reabsorbed in distal tubule with loss of H+
worsening metabolic alkalosis and producing and acidic urine
DEHYDRATION
- in ability to absorb enteral fluid and vomiting
- activation of rennin-AG-ALD system + ADH
PARADOXICAL ACIDURIA
- in order to prevent hypokalaemia
MANAGEMENT
Fluid resuscitation
Fluid resuscitation determined by weight and degree of dehydration assessed clinically (tissue
turgor, pulse, fontanelle, CR centrally, peripheral perfusion, respiratory rate)
- IV boluses of normal saline or colloid (4% albumin) – 10-20mL/kg to restore circulating
volume
- maintenance @ 4mL/kg/hr with 5% dextrose with 0.45% normal saline and 20mmoL KCl
- fluid therapy should be titrated to clinical variable including urine output (2mL/kg/hr)
- need a lot of K+ once they pee
Laboratory criteria by which patient is sufficiently resuscitated for surgery
- ideally biochemical abnormalities would be normal before surgery however, variable
associated with adequate resuscitation and resolution of metabolic alkalosis include:
-
serum Cl- of at least 105mmol/L
serum HCO3- (normal)
urinary Cl- of >20mmol/L
urinary K+
urinary Na+
Intraoperative
- operation = splitting of the pylorus muscle longitudinally down to the mucosa
(myomectomy)
- risk of pulmonary aspiration from gastric outflow obstruction
- aspirate N/G and don’t remove as will help to decompress stomach from vigourous
ventilation
Jeremy Fernando (2010)
-
RSI or use of NDNMBD
fentanyl 1mcg/kg
paracetamol suppository 30-40mg/kg
bupivacaine infiltration
extubate awake and in left lateral position
Postoperative
-
remove N/G
feed within 6 hours
give maintenance IVF until feeding established
use apnoea alarm overnight
Jeremy Fernando (2010)