Flashcards in Pediatric Anesthesia Deck (49)
Name the components of Tetrology of Fallot.
1- Overriding aorta
2- right ventricular hypertrophy
3- Pulmonary artery stenosis
What syndrome is highly associated with Tetrology of Fallot?
What are two coexisting diseases that have a high concordance with malignant hyperthermia?
Central core disease and King-Denborough syndrome
How does pyloric stenosis present?
- Presents between 2-6 weeks of age
- Males > females
- olive-shaped mass between the midline and RUQ
- gastric obstruction leads to projectile, nonbilious vomiting and electrolyte imbalance.
- a hypochloremic, hypokalemic, metabolic alkalosis with compensatory respiratory acidosis.
- with further fluid loss, prerenal azothemia may lead to severe dehydration, hypovolemic shock, and metabolic acidosis. Hypoglycemia may be present due to malnutrition.
- Treatment is a pyloromyotomy.
- Non-emergent surgery --> resuscitate with fluids and electrolytes. Aspirate stomach contents with OG tube prior to induction to minimize the risk of pulmonary aspiration --> MUST do RSI.
Preoperative fasting recommendations in infants and children:
- clear liquids
- breast milk
- infant formula or light meal
- clear liquids- 2 hours
- breast milk- 4 hours
- infant formula or light meal- 6 hours
- solids- 8 hours
Differences in respiratory physiology in children vs adults:
- oxygen consumption
- alveolar ventilation
- closing capacity
- total lung capacity
- tidal volume
- oxygen consumption and alveolar ventilation are twice as high in infancy than in adulthood
- closing capacity is approximately half of TLC in infancy
- FRC and TLC are unchanged throughout life
Infant's laryngeal anatomy
- infant's larynx is more cephalad (superiorly) in the neck at the level of C3-4 vs C4-5, making airway obstruction by the relatively larger tongue more likely
- narrowest part of the infant airway is at the level of the cricoid cartilage as opposed to the rima glottidis in adults
- epiglottis of an infant is narrower and stiffer than that of an adult and omega-shaped and angled more posteriorly
Describe the Pierre-Robin sequence.
- glossoptosis (the abnormal posterior displacement or retraction of the tongue)
- cleft palate
Patients with this syndrome may result in airway obstruction and difficult intubation due to a small anterior mandibular space, contributing to airway obstruction between the tongue and posterior pharyngeal wall.
Describe the AGPAR score.
T or F: elective surgery should be postponed whenever possible until after 54-60 weeks postconceptual age, at which point respiratory control is mature and no special measures need be taken in the otherwise healthy ex-premie.
True- a minimum of 12 hours of monitoring is recommended for ex-preterm infants
Describe omphalocele vs gastroschisis.
Omphalocele- twice as common as gastroschisis and occurs more frequently in premature infants. Associated with cardiac, GI, GU, Beckwith-Wiedeman syndrome. Small bowel are in a sac.
Gastroschisis- results from occlusion of the omphalomeseneric artery during gestation. No covering of the organs and a surgical emergency.
Describe congenital diaphragmatic hernia.
Usually left-sided, morbidity and mortality result from pulmonary hypoplasia and associated pulmonary vascular disease.
Gentle ventilation strategies that preserve spontaneous ventilation with low inspiratory pressure support (< 25 cm H2O) minimize lung distention and barotrauma and correlate with improved survival.
Permissive hypercapnia is considered acceptable as long as the pH remains greater than 7.25 and PaCO2 is less than 60 mm Hg.
What is the induction agent of choice in a patient with Tetrology of Fallot? Why?
In tetrology of Fallot, you want to make sure that you don't drop preload with induction. Cyanosis occurs as a result of right to left shunting across the VSD. The degree of cyanosis is dependent on the degree of shunting which depends on systemic vascular resistance.
Ketamine maintains SVR and is the induction agent of choice in tetrology.
For a child with a recent URI, proceed with the case if:
1- no thick secretions or fever
2- LMA or mask ventilation is planned
3- patient is not wheezing
T or F: airway reativity following a URI is increased for 4-6 weeks.
T- the incidence of bronchospasm, laryngospasm, hypoxia, atelectasis, and post-intubation croup is increased in patients with URIs, but this doesn't impact morbidity. These problems are greatly increased with intubation and less with LMA and mask.
Formula for calculating ETT size
(age/4) + 4
Formula for calculating ETT depth
(age/2) + 12
(kg/5) + 12
3 x diameter of ETT
Describe post-intubation croup? What is the treatment?
Occurs secondary to airway swelling. Edema is self-limited, but impossible to know if it will get worse or better, so it is good treat with racemic epinephrine.
Racemic epinephrine helps to decrease swelling immediately by constricting exposed vessels.
What causes laryngospasm? What is the treatment?
Laryngospasm occurs secondary to superior laryngeal nerve stimulation, thought to be secondary to secretions falling on the glottis during the hyperarousal phase of volatile anesthesia. Treatment is positive pressure ventilation.
Case study: "A child in the ED, sitting forward, drooling, in respiratory distress." X-ray demonstrates the thumb sign. What is your clinical diagnosis? How do you manage the ariway if the patient ate 6 hours ago?
Epiglottitis. Caused by H. influenzae, but the incidence is greatly decreased given that there is a vaccine for this.
This is an airway emergency, especially with signs of respiratory distress. Airway algorithm is as follows:
1- do not delay intubation for definitive diagnosis
2- call ENT for backup
3- bring patient to OR where backup emergency airway equipment is available.
4- avoid significant sedation, as can lead to airway obstruction.
5- Inhalational induction or awake fiberoptic preferred. Pt should be in semi-recumbent position.
What is croup?
Inflammation of the larynx, trachea, and bronchi, which at the narrowest part of the airwa (just below the glottis), nearly occludes air movement. Leads to stridor, hoarseness, and barking cough.
Most cases are due to parainfluenza virus.
Treatment is with racemic epinephrine.
What are triggering agents for malignant hyperthermia?
Halogenated volatiles and Sch
T or F: massiter muscle spasm is a reason to cancel surgery.
In pediatric patients, MMS after sux administration may be the beginning signs of MH. Do a halothane caffeine contracture test. Can observe for 24 hours or, if pt has susceptibility, can administer dantrolene.
What is a highly sensitive test for MH?
Halothane caffeine contracture test
T or F: MH can occur both intraoperatively and postoperatively. Consensus is to observe the patient for 6 hours.
When preparing an anesthetic machine for a malignant hyperthermia patient, what 4 things should you do?
1- flush the machine with 10L/min oxygen for 20 min
2- replace fresh outlet gas hose
3- replace CO2 absorbent and canister
4- replace the circle system
T or F: both thiopental and pancuronium can raise the triggering threshold for MH.
True- in this sense, they are protective against MH.
T or F: hypocalcemia can increase the risk of laryngospasm.
True- tetany, the involuntary contraction of muscles, is a common sign of hypocalcemia
Digeorge syndrome and CATCH-22
Cardiac (tetrology of fallot)
All due to deletion on chromosome 22
What are the most commons yndromes associated with Pierre-Robin sequence?
Stickler syndrome, velocardiofacial syndrome, and Treacher-Collins Syndrome
In a child with congenital lobar emphysema, what is a preferred induction method?
The primary concern is managing the airway in an infant with pre-existing respiratory compromise without making the respiratory distress worse. Use inhalational agents and maintain spontaneous ventilation. PPV may cause more respiratory compromise. Nitrous oxide is contraindicated.
Patients with congenital lobar emphysema will have decreased breath sounds and hyperresonance on physical exam. A CXR will reveal hyper-inflation.
T or F: a total spinal block in a patient receiving a caudal manifests itself as apnea and immobility with no change in heart rate or blood pressure.
True- total spinal anesthesia will present as respiratory insufficiency rather than as hypotension because of the lack of sympathetic tone in infants. Consequently, the first indication of a high spinal is falling oxygen saturation rather than a falling blood pressure.
Conditions that place neonates at risk for reversion to fetal circulation include:
- meconium aspiration
- diaphragmatic hernia
T or F: the administration of IV caffeine is a therapeutic option in the treatment of the prevention of apnea in a premature infant and postoperatively. Side effects include tachyarrhythmias and irritability.
What percentage of fetal cardiac output travels through the patent ductus arteriosus? Through the foramen ovale?
foramen ovale- 33%
When is high frequency ventilatory oscillation used?
High-frequency ventilation is a technique that may optimize ventilation while minimizing gastric distension by minimizing the peak inspiratory pressure. It has been used for many years in pediatric and neonatal respiratory disorders, notably in the ventilation of tracheo-esophageal fistula patients. High-frequency ventilation usually provided as high-frequency oscillatory ventilation (HFOV) attempts to provide adequate gas exchange for patients with severe respiratory compromise while minimizing the risk of ventilator-induced lung injury.
Typical settings during HFOV include FIO2, frequency, amplitude, inspiratory time (as a ratio of inspiratory to expiratory time), inspiratory bias gas flow rate. Tidal volume is traditionally very low (most commonly less than the anatomic dead space) and is neither monitored nor set on the ventilator.
T or F: A healthy term neonate reaches the lowest hemoglobin at 8–12 weeks of postnatal age (48–52 weeks postconceptual age)
The hypoxemia of the fetus in utero is a strong stimulus for erythropoietin (EPO) production, which in turn stimulates erythropoiesis. Consequently, relative polycythemia develops in the fetus—the mean value for hemoglobin concentration in umbilical cord blood at the time of birth in a healthy term neonate is 16.8 g/dL
At birth, the increase in PaO2 results in a significant increase in arterial oxygen content. The resolution of hypoxemia results in a dramatic reduction in EPO levels and erythropoiesis. Decreased production of new red blood cells (containing adult hemoglobin, HbA, as opposed to fetal hemoglobin, HbF) combined with shortened red blood cell survival (80–100 days for a term neonate vs 120 days for an adult) results in a progressive decrease in hemoglobin concentration. Normally the nadir for hemoglobin is reached at approximately 8–12 weeks and the lowest normal value is approximately 8–9 g/dL
Describe a patent ductus arteriosus.
A congenital disorder of the neonatal heart whereby the ductus arteriosus fails to close. In utero, the DA functions to shunt blood from the RV away from the lungs, thereby sending oxygenated blood to the remainder of the neonate's body.
After birth, the aortic pressure exceeds the right ventricular pressure, so a left to right shunt is formed unless the PDA closes.
T or F: the timing of clamping the umbilical cord has several positive effects on the premature neonate.
True- these include higher hematocrit, fewer transfusions, and decreased risk of IVH.
Delayed clamping of the umbilical cord has no impact on APGAR scores.
What are the mean heart rates for neonates of the following ages:
< 24 hours
1 week to 1 month
< 24 hours: 120 bpm
1-7 days: 135 bpm
1 week to 1 month: 160 bpm
3-12 months: 140 bpm
What agent can you give to maintain a patent ductus arteriosus? What agent can you give to close a patent ductus arteriosus?
To maintain a PDA: give prostaglandin
To close a PDA: give indomethacin
Normal physiologic variables for a neonate: HR, BP, RR
Heart rate of 120 to 160 beats/min
Blood pressure range from 65 to 85 mm Hg systolic and 45 to 55 mm Hg diastolic
Respiratory rate of 40 to 60 breaths/min
Studies on normal term newborns demonstrate that in the majority of neonates oxyhemoglobin saturation as measured by pulse oximetry is less than 90% for the first 5 minutes after delivery. By the first or second day after birth, the expected room air PaO2 for a healthy neonate is approximately 60 to 90 mm Hg; this would translate into a room air oxygen saturation value of approximately 88% to 95%.
What is Klippel-Feil syndrome and why important from an anesthetic perspective?
- triad of short neck, low posterior hair line, and congenital spinal fusion causing limited neck mobility.
- Fused segments of the cervical spine in patients with this syndrome promote hypermobility at unfused spine segments, increasing the risk of neurologic compromise during neck manipulation.
T or F: The serum glucose in an otherwise healthy 2-day-old neonate would be expected to range from 50 to 90 mg/dL. Treatment for hypoglycemia in a neonate should be strongly considered for glucose values less than 40 mg/dL.
T or F: Neonates have an increased proportion of hemoglobin F, which contributes to the elevated hemoglobin value at birth. The hemoglobin value in an otherwise healthy 2-day-old neonate would be expected to range from 15 to 20 g/dL.
T or F: Neonates are unable to fully concentrate urine, which results in a loss of sodium. This phenomenon, combined with a reduced muscle mass, contributes to a lower serum creatinine level than in adults. The serum creatinine in an otherwise healthy 2-day-old neonate would be expected to be less than 0.8 mg/dL.
T or F: Neonates are expected to have a normal platelet count compared with adults. The platelet count in an otherwise healthy 2-day-old neonate would be expected to range from 250 to 450 x 103/mm3.
Mean heart rate:
a) neonate < 24 hours old
b) 1-7 days
c) 1 week - 1 month
d) 3-12 months
a) 120 bpm
b) 135 bpm
c) 160 bpm
d) 140 bpm