Peds 2 Flashcards
Describe the events of bilirubin creation and metabolism starting with hemoglobin breakdown
♣ Hemoglobin broken down into heme and globin
♣ Heme then broken down into iron and protoporphyrin
♣ Protoporphyrin converted into unconjugataed bilirubin (water insoluble)
♣ UCB binds to albumin to be brought to the liver
♣ Liver conjugates UCB into CB (water soluble)
• UDP glucuronyl transferase (UGT) is the enzyme in the hepatocytes that conjugates bilirubin
♣ CB dumped into bile canaliculi to be sent to the gallbladder
Causes of elevated unconjugated bilirubin (broad categories)
- Increased bilirubin production
- Impaired bilirubin uptake and storage
- Decreased UDP-GT activity
Causes of increased bilirubin production
- Hemolytic anemia
- Sickle cell disease
- Hematoma breakdown
Causes of impaired bilirubin uptake and storage
- Viral hepatitis
- Drugs
Causes of decreased UDP-GT activity
- Gilbert syndrome
- Crigler Najjar syndrome
- Neonatal physiologic jaundice
Causes of elevated conjugated bilirubin (general categories)
- Impaired transport of bilirubin
- Biliary epithelial damage
- Intrahepatic biliary obstruction
- Extrahepatic biliary obstruction
Causes of impaired transport of bilirubin
- Dubin Johnson syndrome
- Rotor syndrome
Causes of biliary epithelial damage
- Hepatitis
- Cirrhosis
- Liver failure
Causes of extrahepatic biliary obstruction
- Pancreatic neoplasms
- Pancreatitis
- Cholangiocarcinoma
- Choledocholithiasis
Describe physiologic jaundice of the newborn
- Newborn livers have low UGT activity (enzyme that conjugates bili), leading to increased UCB
- Too much UCB can deposit in the brain kernicterus
- Treatment = Phototherapy – makes UCB water soluble
Describe physiologic jaundice of the newborn
- Newborn livers have low UGT activity (enzyme that conjugates bili), leading to increased UCB
- Too much UCB can deposit in the brain kernicterus
- Treatment = Phototherapy – makes UCB water soluble
Most common hemolytic causes of hyperbilirubinemia
- ABO or Rh incompatibility
- Sepsis
- Membrane disease
- Enzyme defects (G6PD or pyruvate kinase deficiency(
- Hemoglobinopathies (sickle cell, thalassemia)
What is breast milk jaundice
Thought to be due to human milk causing increase of intestinal absorption of bilirubin
Describe breastfeeding failure jaundice
Decreased intake causes slower bilirubin elimination and increased intrahepatic circulation
Describe why high bilirubin is dangerous
UCB can cross the BBB and cause cell death by apoptosis and necrosis
Describe major features of kernicterus
- Choreoathetoid cerebral palsy
- Significant hearing loss due to auditory neuropathy
- Gaze abnormalities, especially limitation of upward gaze.
- Dental enamel dysplasia
What is acute bilirubin encephalopathy (ABE)
Usually occurs before kernicterus
3 phases:
- Sleepy but arousable with possible hypotonia
- febrile, lethargic, irritable, hypertonia
- apnea, inability to feed, seizures, coma
How does G6PD deficiency cause hyperbilirubinemia
♣ Glutathione neutralizes H2O2 but becomes oxidized in the process
♣ NADPH needed to reduce glutathione
In G6PD, no NADPH created in order to reduce glutathione, which is needed to protect RBCs from oxidative damage
What is haptoglobin
Protein that carries Hb to the spleen
Will have decreased serum haptoglobin in hemolysis
How does pyruvate kinase deficiency cause hyperbilirubinemia
♣ Glycolytic enzyme deficiency = inability to generate ATP
♣ Cannot maintain Na+/K+ ATPase = RBC swelling and lysis
Describe neurostorming
Following TBI, caused by increased stress response (corticoids and catecholamines)
Symptoms can include alterations in level of consciousness, increased posturing, dystonia, hypertension, hyperthermia, tachycardia, tachypnea, diaphoresis, and agitation
What is refeeding syndrome
he refeeding syndrome is defined as the clinical complications that can occur as a result of fluid and electrolyte shifts during aggressive nutritional rehabilitation of malnourished patients
Clinical features of refeeding syndrome
●Hypophosphatemia (*hallmark) - lack of phosphate (ATP) leads to tissue hypoxia, causing myocardial dysfunction and respiratory distress
●Hypokalemia
●Vitamin (eg, thiamine) deficiencies
●Congestive heart failure
●Peripheral edema
●Rhabdomyolysis
●Seizures
●Hemolysis
Describe difference between acetylcholinesterase inhibitor toxicity and direct cholinomimetic toxicity
Unlike direct acting cholinomimetics, acetylcholinesterase inhibitors effect nicotinic receptors in addition to muscarinic receptors
Clinically = flaccid paralysis + DUMBBELS
Describe DUMBBELS sx of ACh inhibitor toxicity
D = diarrhea U = urination M = miosis B = bronchospasm B = bradycardia L = lacrimation S = salivation
MOA of Pralidoxime
Used to treat PERIPHERAL effects of ACh inhibitor toxicity
Regenerates ACh esterase at muscarinic and nicotinic receptors (reverses paralysis as well)
MOA of Atropine
Treats both PERIPHERAL and CENTRAL effects of AChI toxicity on MUSCARINIC receptors
But does not reverse nicotinic effects, so does not fix paralysis
What are the 5 components of apgar score
HR, RR, muscle tone, reflex irritability, color
What do you do if meconium is present in a vigorous newborn
Bulb syringe or large-bore suction to clear airway
What do you do if meconium is present in a nonvigorous newborn
Intubate and direct suction of trachea before many breaths occur to reduce change of meconium aspiration
Diagnose: newborn born with scaphoid abdomen, cyanosis, and respiratory distress
diaphragmatic hernia
Tx of newborn with respiratory distress in setting of diaphragmatic hernia
Endotracheal intubation
Bag-mask ventilation will also push gas into bowel, which is in the chest cavity, causing further respiratory compromise
Next step in neonatal rescusitation if HR remains < 60 beats/min despite positive pressure ventilation
Chest compressions
Next step if chest compressions fail
Drug therapy (usually epinephrine)
What is choanal atresia and its presentation
Obliteration or blocking of posterior nasal aperture (aka nose is not connected to oropharynx)
Presents as baby who can breathe when crying but has respiratory distress when stops. Infants are obligate nose breathers but can breathe through their mouths when crying
Tx of choanal atresia
Intubation to bypass obstruction until surgical repair can be completed
Describe pathogenesis of infant of a diabetic mother
♣ In response to maternal hyperglycemia, fetal hyperinsulinism begins
♣ Fetal insulin production causes increased glycogen production which is deposited in fetal liver, heart, kidneys, and skeletal muscle
♣ After delivery and removal from high-sugar in utero environment, the infant’s hyperinsulinism can cause hypoglycemia
Clinical features of infant of a diabetic mother
♣ Hypoglycemia – seizures, jittery, apnea
♣ Spinal bifida / neural tube defect
♣ Shoulder dystocia, brachial plexus injury (due to large infant being squeezed during delivery)
♣ Hypertrophic cardiomyopathy (due to glycogen deposition)
♣ Hyaline membrane disease, respiratory distress syndrome
♣ Polycythemia
♣ Hyperbilirubinemia, hypocalcemia, hypomagenesia
♣ Renal vein thrombosis
♣ Caudal regression syndrome
What causes Respiratory distress syndrome in infant of DM mother
♣ insulin interferes with cortisol’s ability to induce surfactant production
What causes hypertrophic cardiomyopathy in infant of DM mother
♣ Fetal insulin production causes increased glycogen production which is deposited in fetal heart
What causes polycythemia in infant of DM mother
Due to increased fetal oxygen requirement because of enlarged fetus
What causes hyperbilirubinemia in infant of DM mother
due to polycythemia
What causes renal vein thormbosis in infant of DM mother
due to polycythemia
Tx of newborn of DM mother with glucose < 40 and NO sx of hypoglycemia
♣ If no sx of hypoglycemia, the infant is refed and glucose re-measured 30 min after feeding
Tx of newborn of DM mother with glucose < 40 and + sx of hypoglycemia
Requires IV glucose
