Pediatric Part 3
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Persistent Pulmonary HTN is a problem of which age??
Problem of term and preterm infants (first 3 days of life)
What is the pathophysiology of persistent pulmonary HTN?
- Pulmonary circulation sensitive to pH, ↑oxygen, and nitric oxide.
- Hypoxia, acidosis, and inflammatory mediators →↑pulmonary artery pressure (pathologic).
- Characterized by extension of smooth muscle into distal respiratory units.
- Causing an increase in PVR
- Vasoconstriction of pulmonary vascular bed → right to left shunt through the FO and DA.
- ↑PVR→↓ Pulm Blood Flow, ↑ Flow through DA. LA pressure < RA pressure and FO opens.
What are the causes and treatment of persistent pulmonary HTN?
- May be primary or secondary: results from meconium aspiration, sepsis, pneumonia, respiratory distress, CDH.
- Treatment is goal directed: includes surfactant and ventilatory techniques
What is meconium aspiration?
- Fetal Hypoxia → ↑ in muscles of distal respiratory units.
- Chronic fetal hypoxia → passage of meconium in utero.
- Meconium mixes with amniotic fluid.
- Meconium aspiration may be a marker of fetal hypoxia in the third trimester.
- Differs from meconium at birth.
- Can be fatal despite treatment modalities.
- Routine oral suctioning vs. tracheal suctioning. (high vs. low APGAR scores)
What is bronchopulmonary dysplasia and what patient population does it occur in?
- Inflammation and scarring of lung parenchyma and small airways.
- Often results from long term ventilation of premature infants treated for RDS.
- Occurs in Very premature infants and low birth weight infants (500g – 1 kg.)
Low weight infants who require vent support during the first 3 days of life have an ___% chance of developing BPD.
What is bronchopulmonary dysplasia characterized by?
- Characterized by ↑ airway reactivity; ↓ lung compliance; VQ mismatch, hypoxia, and tachypnea.
- ↑ O2 consumption by 25%.
What are the anesthetic considerations for bronchopulmonary dysplasia?
- Maintain PaO2 > 55 O2 sat > 94%.
- Use ETT one size smaller.
- Intubate deep.
Respiratory distress syndrome is responsible for __-__% of deaths in preterm neonates.
What is the pathophysiology of respiratory distress syndrome?
- Progressive impairment of gas exchange at alveolar level due to deficient production and secretion of surfactant.
- Right to Left shunting, arterial hypoxia, and metabolic acidosis.
Mature level of surfactant are not present until ___ weeks gestational age.
What are the s/s of respiratory distress syndrome?
- Tachypnea, intercostal and substernal retractions, nasal flaring, cyanosis. (within minutes after birth)
- Apnea and irregular respirations may be a sign of fatigue—failure. (require immediate intervention)
- Diagnosed with chest radiograph, clinical course and blood gas analysis.
How do we care for patients with respiratory distress syndrome?
- Infants with severe cases; PaO2 < 50 on 70%- 100% O2 therapy require mechanical ventilation.
- Maintain PaO2 55-70 mmHg; PaCO2 45-65 mmHg; pH 7.25-7.45.
- Risk of pneumothorax due to barotrauma. (watch for sudden drop in PaO2.)
- Maintain HCT of 40%Use Albumin for hypotension. (careful hydration)
What is the definition of apnea? What different types are there?
- Cessation of breathing that lasts 20 seconds or longer or is accompanied by bradycardia or cyanosis.
- Idiopathic apnea of prematurity.
- May be obstructive, central, or mixed.
- Obstructive-- Neck flexion, pharyngeal instability, nasal obstruction
- Central– Immature respiratory control mechanism
What is the onset of apnea usually??
Onset is usually 2 to 7th day of life.
Why do we give oxygen therapy for apnea?
Oxygen therapy– improves CO2 sensitivity, ↓ hypoxic respiratory depression, decreases periodic breathing, and enhances diaphragmatic strength
What anesthetic considerations do we have for apnea in pediatrics?
- Keep HCT at 40%
- Anesthetics (inhaled or IV) affect the control of breathing. (12 hours post surgery).
- Regional anesthesia with no sedation reduces but does not eliminate risk of apnea.
- Ex-premature infants with history of apnea are not well suited for outpatient surgery.
Name the Right to Left cardiac shunts
ASD, VSD (25%), PDA, endocardial cushion defect (trisomy 21).
Name the Left to Right cardiac shunts
TOF (10%), Pulmonary atresia, Tricuspid atresia, Ebstein’s anomaly.
What is the anesthetic management for patients with congenital heart defects?
- Avoid drops in SVR
- Maintain intravascular volume
- Beta blockade to control Heart rate.
- R>L shunting may slow induction of inhalation agents
- Avoid acidosis
- Maintain normal airway pressuress
- Consider Ketamine/ narcotic anesthetic
What is the pathophysiology that occurs when L to R shunting??
- Defects connecting arterial & venous circulation
- SVR > PVR → ↑ PBF
- ↑ pulmonary blood flow → pulmonary congestion → CHF → ↑ susceptibility to Resp. Tract Infection
- Long standing L-R shunts → PHT
- (PVR > SVR → R-L shunt → Eisenmenger’s syndrome)
What happens with R to L shunting??
- Defect between R and L heart
- Resistance to pulmonary blood flow → ↓ PBF → hypoxemia and cyanosis
When does the PDA usually close?
- PDA beyond the fourth day of life is abnormal.
- Most PDA close 24 to 48 hrs post birth. (frequently fails to close in premature infants).
Treatment for PDA is surgical closure done percutaneously and with low mortality. What are the risks associated with this surgery and what is the medical option?
- Risk can be ICH, infection, recurrent laryngeal nerve paralysis (infants born <28 weeks)
- Medical treatment with COX II inhibitors (Indocin)
What are the anesthetic considerations for PDA?
- Abx to prevent endocarditis
- VA may decrease L to R shunting.
- Positive pressure ventilation is well tolerated
- Consider nipride post op if SVR is elevated
What is necrotizing enterocolitis and what is it caused by?
- Characterized by ulceration and necrosis of the small bowel and colon
- Unknown cause; likely multifactoral
What are the s/s of necrotizing enterocolitis?
- Feeding intolerance, abdominal distention, and bloody stools are the most common initial signs.
- Intestinal obstruction, perforation, and sepsis may follow
what is the treatment for necrotizing enterocolitis?
Treatment consists of withholding enteral feeding, nasogastric decompression, intravenous fluids, hemodynamic support, administration of appropriate antibiotics, and surgical exploration if an acute abdomen with free air is evident.
What are the anesthesia implications for necrotizing enterocolitis?
- Pts are hypovolemic with metabolic acidosis
- Metabolic/ fluid and electrolyte deficiencies
- May require fluid ( colloid and crystalloid) resuscitation. Blood products.
- Careful induction or awake intubation
- Caution with anesthetics that depress cardiac function
- Mechanical ventilation post op.
What is hypertrophic pyloric stenosis and how do we treat it?
- HPS interferes with emptying of gastric contents
- Persistent vomiting→hypochloric metabolic alkalosis
- Renal compensation ↑ excretion of NaCO3 →
- paradoxic aciduria
- Correction of metabolic alkalosis requires hydration with a NaCl solution and K.
- Do not use LR
What are the anesthetic implications for hypertrophic pyloric stenosis?
- Surgery should be postponed until fluid and electrolyte abnormalities have been corrected.
- Empty stomach
- High risk of aspiration
- Muscle relaxation
- ↑ Risk for respiratory depression post op due to persistent metabolic or CSF alkalosis.
Hyperbilirubinemia (jaundice)- usually a benign problem in __% of neonates in first week of life. (___% in premature neonates)
What is kernicterus?
- Kernicterus is a neurological disorder caused by toxic effects of unconjugated bilirubin in the brain stem nuclei and basal ganglia.
- (Due to the same problem as hyperbilirubinemia but more severe)
What are the s/s of kernicterus?
- Symptoms may mirror sepsis, asphyxia, hypoglycemia, ICH in first 2 to 5 days of life.
- Lethargy and poor feeding may progress to diminished deep tendon reflexes and hypo/hypertonia.
What are the anesthesia implications for kernicterus?
- Caution with solutions containing benzyl alcohol. (vecurnoium has this once reconstituted)
- Avoid or correct hyperoxia, acidosis, and hyperosmolarity
Fetal Hgb- (HgF) ___% fetal hemoglobin at birth.Largely replaced by Adult Hgb at _-_ months
What are the normal Hemoglobin levels in pediatric patients?
- Preterm = 13-15 g/dl
- Neonate = 17g/dl
- 3 months = 10-11
- 2-5 years = 12.5-13g/dl
- > 5-10 years = 14g/dl
What is retinopathy of prematurity?
- Fibrovascular proliferation overlying the retina
- Associated with premature infants less than 1000Gms
- Hyperoxia is believed to major contributor (Prolonged oxygen therapy).
- Retinal detachment and blindness
What are the anesthetic considerations for retinopathy of permaturity?
- Maintain PaO2 50-80 mHg: PaCO2 35-45 mmHg: O2 sat 89%-94%
- Infants undergoing peripheral retinal ablation have an increased risk of both apnea and bradycardia 1 to 3 days post op.
What are the 4 types of intracranial hemorrhage and which is the most important?
- 4 Types: Subdural, primary subarachnoid, Intercellular, Intraventricular Hemorrhage (IVH)
- IVH is most important type
Intercranial hemorrhage occurs in __-___% of LBWI < 1250 Gms.
What are the anesthetic implications for intracranial hemorrhage?
- Maintain normal BP and avoid large swings.
- Slow volume expansion.
- Correct metabolic imbalances.
- Normal Blood pressure is at low end of autoregulatory limit.
What is the most common metabolic problem in newborns?
What causes hypoglycemia in babies?
- Inadequate glycogen stores and deficient gluconeogenesis are important factors.
- Incidence of symptomatic hypoglycemia is highest in SGA infants
What is the onset and s/s of hypoglycemia?
- Onset is 4 hours to 1 week after birth.
- S/S irritability, Apnea, cyanotic spells, seizures, hypotonia, lethargy.
- Serum glucose rarely < 25-45 mg/dl.
- No absolute established level.
- CNS s/s seen at < 20 mg/dl in PI; < 30 in term infants (for first 72 hours).
What are the anesthetic considerations for hypoglycemia?
- Use glucose containing solutions to correct LBG D5 0.2NS solution. 4ml/kg/hour.
- Caution with resultant hyperglycemia in stressed infants.
- Fluid deficits and third space losses corrected with non glucose containing fluids.
- Serum glucose in excess of 125 mg/dl can result in osmotic diuresis and dehydration.
Who is at risk for hypocalcemia?
- High risk for LBW infants, and premature infants, infants of insulin dependent diabetic mothers, and asphyxia during delivery.
- Late hypocalcemia usually due to ingestion of cow’s milk, maternal hypercalcemia, and DiGeorge syndrome.
What are the s/s of hypcalcemia?
- S/S most common cause of neonatal seizures.
- Also causes irritability, ↑skeletal muscle twitching, tremors, and hypotension
How do we diagnose hypocalcemia?
Dx’d by serum Ca < 8mg/dL in term infants and< 7mg/dL in preterm neonates or serum ionized Ca of < 4.4
How do we treat hypocalcemia?
- Treat immediately with IV calcium (gluconate or chloride)
- Most commonly treated with100 mg/ml of ca gluconate with 9mg of elemental calcium.
- Must replete using cardiac monitor with atropine available.
What is pyloric stenosis?
- Palpable “olive” in RUQ
- Hypertrophy of esophageal sphincter
What are the s/s of pyloric stenosis and treatment??
- s/s – projectile vomiting, met. Alkalosis progressing to met. acidosis, hypokalemia, hypovolemia, hypochloremia, hyponatremia
- Tx: Pyloromyotomy
What are the anesthetic implications for pyloric stenosis?
- Correct metabolic and fluid imbalance
- NGT to suction prior to induction
- Awake intubation and IV induction
- Use normal saline with K+
- Extubate fully awake
What is a type C tracheal esophageal fistula?
- Type C – combination of upper esophagus that ends in a blind pouch and a lower esophagus that connects to the trachea
- Type C is most common (90%) as breathing causes gastric distention and feeding leads to choking and asp. Pneumonia
What does VATER stand for???
- (vertebral defects, anal atresia, tracheo-esophageal fistula, radial
What are the anesthetic considerations for VATER syndrome?
- Frequent suctioning for copious secretions
- Patients are often dehydrated and malnourished
- Avoid positive pressure ventilation and require awake intubation-PPV will causes abdominal distention
- Keep spontaneously breathing with minimal assist until fistula is ligated (100% O2)
- Most important is placement of ET between fistula and carina
What is a congenital diaphragmatic hernia? How often does this happen?
- Gut can herniate into the thorax during fetal development.
- Incidence of CDH is 1 in 5,000 live births
Which side is more common in congenital diaphragmatic hernias?
Left sided herniation is most common type (90%)
What are the hallmark signs of congenital diaphragmatic hernias?
- Hallmarks include hypoxia, a scaphoid abdomen, evidence of bowel in the thorax
- Pulmonary hypoplasia and malrotation of intestines are almost always present
- Often accompanied by PH; and is associated with 40 – 50% mortality
What is the cardiopulmonary compromise in congenital diaphragmatic hernia due to?
d/t pulmonary hypoplasia and hypertension rather than the massive effect of herniated viscera.
What are the anesthetic implications for diaphragmatic congenital hernias?
- NGT placed to alleviate gastric distention/avoid high ventilation pressures
- Awake intubation often without muscle relaxants
- Inspiratory pressures should be less than 30 cm H2O
- Sudden fall in lung compliance, blood pressure or oxygenation may signal a contralateral pneumothorax
- Caution with expansion of ipsilateral lung following surgical decompression
- Anesthetic maintained w/low concentrations of volatiles or opioids.
- Use MR as tolerated
What are the common associated abnormalities with T21??
- CDH (40% of patients, Endocardial cushion defects and VSD), subglottic stenosis, tracheal esophageal fistula, chronic pulmonary infections, and seizures
- Often premature and SGA
What are the anesthetic considerations for T21?
- Often difficult airways, especially during infancy
- Typically use smaller ETTs
- Respiratory complications (stridor and apnea) are common
- Neck flexion may result in A/O dislocation
- Caution with air in IV due to possibility of right to left shunts
Pierre Robin Sequence, how is it genetically passed on??
- Occurs in 1/8500 births
- Autosomal recessive
What are the associated abnormalities with Pierre Robin Sequence?
- Mandibular hypoplasia, micrognathia, cleft palate, retraction of inferior dental arch, glossptosis
- Severe respiratory and feeding difficulties
- Associated with OSA, otitis media, hearing loss, speech defect, ocular anomalies, cardiac defects, musculoskeletal (syndactyly, club feet), CNS delay, GU defects)
What is Treacher Collins syndrome?
- Mandibulofacial dysotosis
- Cheek bone and jaw bone underdeveloped
- External ear anomalies, drooping lower eyelid, unilateral absent thumb
- Respiratory difficulties
- Underdeveloped jaw causes tongue to be positioned further back in throat (smaller airway)
- Associated with OSA, hearing loss, dry eye
- Anticipate difficult intubation & Awake extubation.
What is Metabolic Beckwith-Wiedemann Syndrome
- 50% born prematurly.
- Autosomal dominant
- Macroglossia, Exomphalos, Gigantism
- Associated with mental retardation, organomegaly, abdominal wall defect, pre- and postnatal overgrowth, neonatal hypoglycemia, earlobe pits, Wilms tumor, omphalocele.
- Manage Polycythemia and hypoglycemia.
What are the three features of Klippel-Feil syndrome??
- Short neck
- Restricted mobility of c-spine
- Low hairline
Fusion at C2-C3 is most common in Klippel-Feil Syndrome, what are the three types???
- Type I- massive fusion of many cervical and thoracic segments.
- Type II- Fusion at one or two interspaces.
- Type III- Includes both cervical and thoracic or lumbar segments.
What are the anesthesia implications for Klippel-Feil Syndrome?
- Awake fiberoptic intubation.
- Unstable upper cervical spine (A-C junction).
- Limited neck mobility.Prone to neurologic damage.
- May involve other anomalies: VSD, craniofacial anomalies, Limb deficiencies.
What are the 4 things in Tetralogy of Fallot?
- Right ventricular outflow obstruction
- Over-riding Aorta
- Right ventricular hypertrophy (25% have pulmonary stenosis)
When do Tetralogy of Fallot patients start to see symptoms?
- Neonate deteriorate when PDA starts to close. (and they cry)
- Prostaglandin may be used to keep PDA open
What are the anesthetic implications for Tetralogy of Fallot?
- Keep SVR up, maintain intravascular volume, beta blockade to decrease HR
- R>L shunting may slow induction of inhalation of agents
- Avoid acidosis, increases in PVR and excessive airway pressures
- Consider Ketamine and narcotic anesthetics
What causes acute epiglottitis?
Bacterial infection associated with fever (Haemophilus influenza) lasts 2 – 4 days; Tx-ampicillin
What are the s/s of acute epiglottitis?
- Characterized by Supra-Glottic Edema
- Drooling, difficulty swallowing, lethargy, tachypnea, cyanosis, acidosis, dehydration; best sitting forward
- Causes difficulty swallowing progressing to complete airway obstruction; may proceed to airway emergency. Intubate.
What are the anesthetic implications for acute epiglottitis?
- Intubate in OR if possible or ER in emergency
- No paralysis, may need emergency trach
- Half to 2x smaller ETT tube with cuff leak < 20 cm H2O
- Intubated for 48 – 62 hours, extubate when leak demonstrated
What is Croup (Laryngotracheobronchitis):
- Characterized by sub-glottic edema developing slowly over time in children with URI
- Rarely requires intubation
- Barking cough, stridor, rhinorrhea (less obstruction than epiglottitis)
What is the cause and treatment of croup?
- Usually viral infection with low grade fever in children 3 months to 3 years
- Treatment is racemic epi, nebs, humidified air/O2
- Watch for rebound edema
What kids are at risk for OSA?
- craniofacial abnormalities
- neuromuscular disorders
- adenotonsillar hypertrophy
Apnea index is a measurement of severity of OSA. Basically measuring the apneic events or respiratory disturbances in 1hr of sleep. What is the mild, moderate and severe?
- Mild OSA patient would have 1-5 events/hr. Moderate would be 5-10/hr.
- Severe would be greater than 10/hr.
Which kids are at risk for post-op complications (in the apnea slides)???
- 1) age younger than 3 years;
- (2) abnormal coagulation values;
- (3) evidence of OSA;
- (4) systemic disorders (metabolic diseases)
- (5) presence of craniofacial or other airway abnormalities;
- (6) peritonsillar abscess
- (7) Social and logistical challenges (smoking parents, sleeping w/allergens, etc.)
What anesthesia considerations do we have for the patient with OSA?
- Higher sensitivity to the respiratory depressant effects of narcotics. (Upregulated Mu receptors due to minor hypoxic events, and response to carbon dioxide.)
- Narrowed upper airway
- Propensity to upper airway collapse.
What do we do in the pre-op assessment for OSA?
- History and exam.
- Consult ENT or pulmonolgy for severe cases.
- Optimal preop condition.
- 23 hour admit or ICU postoperatively
What do we do for intra-op mangement of OSA?
- Non narcotic meds ( toradol, Acetaminophen PR)
- Short acting narcotics
- Regional or local anesthesia for post op pain.
- Dexamethasone (0.0625 mg/kg - 0.15 mg/kg)
We need to evaluate the patients condition at home whether you’ll do the procedure at that facility. What types of things would we be considering?
- Kids w/cardiac dysfunction or cor pulmonale needing ICU and ventilation places the patient at increased perioperative risk.
- Children that live long distances from an adequate health care facility or have home conditions not consistent w/observation may not be able to do ambulatory surgery or be able to return quickly to a medical facility.
Apnea can be mixed, central, or obstructive. ___-____% of apnea tends to be mixed (central and obstructive) but _____ apnea is usually a shorter duration.
50-75%; but central is usually a shorter duration
Hct less than ___% is a risk for apnea irrespective of post-conceptual age or post gestational age.
Infants under ___ weeks post conceptual age are most at risk for apnea. Most will postpone non essential surgery on any infant until __ weeks post conceptual age.
60; 52 weeks
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