Pediatric Anesthesia Exam 2
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. What would you like to do?
1.25 mg/kg PO
Lasts 3-6 hours
Tagamet is not useful if given ___ hours before surgery
4 hours. Needs one hour to take effect. Tagamet induces the CYP 450 enzyme
induces gastric emptying by antagonizing dopamine.
directly works on chemoreceptor trigger zone for antiemetic effect
100-150 mcg/kg q 6 hours
Zofran class and advantages
Class- serotonergic antagonist (5HT3)
Advantages- prevents N/V and decreases severity of existing N/V
Which two of the following drugs are tertiary amides?
Scoplamine, atropine, robinol, aspirin
Scop and atropine. They can cross the BBB.
IM dose of Succinylcholine
3mg/kg in infants
1.5-2 mg/kg in children
Which anticholinergic is the most effective antisialogogue?
What do you do if your patient goes into cardiac arrest from hyperkalemia?
- 1. hyperventilate
- 2. give 2-4 mg/kg calcium choloride
- 3. give dextrose 0.5 g/kg with insulin 0.1 unit/kg
- 4. give kayexelate 1-2 grams/kg
shorter acting in peds than in adutls
nimbex mode of elimination
pH and temp dependent
Vec and Roc mode of elimination
hepatic and renal
< 1 year= 0.07 to 0.1 mg/kg
children= 0.1 mg/kg
considered long acting in peds
1.2 mg/kg for RSI
Used for cardiac surgery for HR support
What are children more susceptible to with inadequate NMB reversal?
Hypoxemia and CO2 retention
Which muscle is the best indicator of diaphragm function when considering reversal?
adductor pollicis. It is more sensitive to NMB than the diaphragm, so if the adductor pollicis shows a TOF of 4, we can be confident that the diaphragm is functional. The diaphragm is one of the last muscles to be affected by NMB and one of the first to come back.
What is the principle factor in determining lung compliance?
When I say compliance, you say
Volume increases throughout childhood, and is the principle determining factor for compliance
The highest negative pressure generated for a neonate is
70 cm H2O.
Adults is 100 cm H2O
Law of LaPlace
Neonates cannot suck in big volumes of air b/c their airways collapse b/c of the relatively increased tension
Functional residual capacity
The volume of air that remains in the lungs at the end of each normal expiration
The FRC of an infant is set by an automatic stopping of exhalation at a long volume in excess of the relaxation volume. They have a prolonged expiration constant.
Specific airway resistance
the reciprocal of resistance (1/R)
smaller airways=higher resistance
is higher in preterm infants and decreases thru the 1st 5 years of life
At what age do the number of alveoli increase exponentially?
5 years old.
Significantly decreased resistance.
peripheral chemoreceptors in carotid and aortic bodies
PaCO2 and pH
central chemoreceptors in the medulla oblongata
Tracheal compliance in newborns is ____ that of adults
Importance in possibility of tracheal collapse during inspiration and expiration
What neural circuit group in the ventrolateral medulla are thought to be the respiratory rhythm center generators?
pre-Botzinger complex and retrotrapezoid nucleus/parafacial respiratory group
when does the vast majority of alveolar formation occur?
How many terminal sacs does the neonatal lung have at birth typically?
10-20 milling terminal air sacs
Changes in what elicits an acute decrease in pulmonary blood flow?
Describe the pressure changes that causes functional closure of the left to right one-way flap valve across the foramen ovale?
- increased left atrial pressure
- decreased right atrial pressure
List four respiratory issues that are especially important to the pediatric popluation
- 1. upper respiratory tract infections
- 2. Reactive airway disease/asthma
- 3. Ventilatory problems relating to prematurity
- 4. Congenital diesases
Name four interventions that may relieve laryngospasm
- 1. jaw thrust
- 2. positive pressure
- 3. IV lidocaine
- 4. IV succinylcholine (this WILL work)
Where is the smallest part of the pediatric trachea?
Often times it is below the cords b/c the pediatric trachea tends to taper in diameter
(the underdeveloped cricoid cartilage)
What cervical level does the pediatric larynx lie?
C 3- C 4
Glottic opening in a preterm infant is at what cervical level?
Glottic opening in a full term infant is at what level?
Glottic opening in an adult is at what cervical level?
Factors that make pediatric airways different from adults include?
- Relatively larger tounge
- angled vocal cords
- differently shaped epiglottis (ohmega)
- funnel shaped larynx
What are the age parameters for uncuffed ETT use?
< 8 years old
A tight fitting ETT may cause edema and trouble upon extubation
If radius is halved, resistance increases 16 times
- Normal infant tracheal radius is 4 mm
- Adults is 8 mm
Infants have 16 times the resistance to air movement than adults to start with. Edema and secretions are not tolerated well.
The high larynx position and position of the tongue
results in poor coordination between the respiratory efforts and oropharyngeal motor/sensory input that is immature
Presence of Upper respiratory infection may preclude:
- post-intubation subglottic edema
Snoring or noisy breathing indicates:
upper airway obstruction or OSA
inspiratory stridor may be heard with:
- subglottic narrowing
- laryngeal web
- extrathoracic foreign body
- extra thoracic tracheal comression
hoarse voice may indicate:
- vocal cord palsy
Treat with bronchodilator
Repeated pneumonias indicate
- incompetent larynx (aspiration)
- cyctic fibrosis
- TE fistula
- immune supression
- congenital heart disease
Expiratory sound is
may indicate lower airway disease
What is the biggest mistake committed by SRNAs in pediatric airway maintence?
Improper mask technique. Obstruction by improper placement of hand around soft tissue below jawline.
KEEP YOUR HAND ON THE BAG
Why should you consider avoiding nasal trumpets in children?
Hypertrophied adenoid trauma can lead to significant bleeding
What is an appropriate intervention to make during the alignment phase in preparation for endotracheal intubation?
infants and children < 6 years old benefit from no placement of a pillow or sheet beneath the occiput for best visualization because they have proportionally bigger heads than persons > 6 years old
What can you do to treat post-extubation croup?
humidified mist and racemic epinephrine
ETT size for neonate to 6 months
3 to 3.5
ETT size for 6 months to 1 year old
3.5 to 4.0
ETT size for 1-2 years
ETT size for > 2 years old
age in years + 16 divided by 4
What is the peak inspiratory pressure for an appropriate leak with proper ett size
20-35 cm H2O PIP
What is the cause 90% of the time for laryngotracheal subglottic stenosis?
endotracheal intubation, especially for a long time
Name three advantages for use of LMA
- 1. no increase in IOP
- 2. allows for oxygenation & ventilation
- 3. can use in asthma patients
LMA is like swallowing a mask. It does nothing for laryngospasm
Ideal LMA cuff position
- Superior- base of tongue
- Lateral - piriform recess
- Inferior- upper esophageal sphincter
LMA size for neonate/infant up to 5 kg
LMA size for infants 5-10 kg
LMA size for infants/children 10-20 kg
LMA size for children /small adults 30-50 kg
LMA size for adolescents/adults 50-70 kg
LMA size for large adolescents/adults 70-100 kg
LMA size for children 20-30 kg
Name contraindications for LMA use
- decreased peristalsis
- pharyngeal pathology
- pharyngeal obstruction
- restrictive airway disease requiring high pressures to ventilate
- any surgical procedure other than supine
- anticipated surgical time > 2 hours
Ketamine IV dose
0.25-0.5 mg/kg q 2 minutes, titrate to effect
When I say ketamine, you think
- NMDA receptors
- maintains spontaneous breathing
What can you give with ketamine to decrease the psychomimetic emergence reactions?
anticholinergic (robinol or scop) + benzodiazepine (versed)
Why do we not use cetacaine in patients less than 40 kg?
Because it's associated with methhemogobinemia and is difficult to titrate
disorder characterized by the presence of a higher than normal level of methemoglobin (metHb, i.e., ferric [Fe3+] rather than ferrous [Fe2+] haemoglobin) in the blood. Methemoglobin is a form of hemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen. However, the ferric iron has an increased affinity for bound oxygen. The binding of oxygen to methemoglobin results in an increased affinity of oxygen to the three other heme sites (that are still ferrous) within the same tetrameric hemoglobin unit. This leads to an overall reduced ability of the red blood cell to release oxygen to tissues, with the associated oxygen–hemoglobin dissociation curve therefore shifted to the left. When methemoglobin concentration is elevated in red blood cells, tissue hypoxia can occur.
Criteria for extubation:
- Pt must be fully awake
- Have adequate ventilatory effort
- Be fully reversed
What can you give if airway edema is suspected?
decadron 0.5 mg/kg IV
What can you do if you can't ventilate and suspect a subglottic or glottic obstruction?
Percutaneous Needle Cricothyrotomy
Vagal response with alveoli overinflation
Term infant Hgb, HCT, WBC, PT/INR
16.8 g/dL, 55 %, 18000 mmcubed, 13 seconds
One year old HGB, HCt, WBC, PT/INR
12 g/dL, 36 %, 10,000 mm cubed, 11 seconds
What risks are magnified in the setting of operative blood loss and anemia?
- postoperative apnea
When to transfuse FFP
- Documented congenital or acquired coagulationfactor deficiency where a specific factor is unavailable
- Acquired coagulopathy secondary to massive transfusion
- Immediate reversal of warfarinDIC, TTP
When to transfuse Cryoprecipitate
- Anticipated bleeding in von Willebrand disease unresponsive to DDAVP
- Acquired hypofibrinogemia associated with massive transfusion
Clinical signs of hemolytic anemia
Subdivisions of hemolytic anemia's
- 1. RBC membrane defects (ex. hereditary spherocytosis)
- 2. enzymatic defects (ex. G6PD deficiency)
- 3. qualitative and quantitative defects (ex. sickle cell and thalassemia)
What is the most common cause of inherited chronic hemolysis in North America and northern Europe
Classic triad of symptoms with hereditary spherocytosis
Diagnosis from RBC smear and central pallor of RBC spherocytes
Gold standard of hereditary spherocytosis diagnosis
Osmotic fragility test
produces age-related results and must be preformed by experienced lab technicians
When I say protein, you say
Colloid osmotic pressure
- Albumin- large protein
- Hetastarch- large carbohydrate
G6PD deficiency diagnosis
- Heinz bodies
- normocytic anemia
Presenting signs= anemia and jaundice
What other conditions do G6PD emulate?
- anemia of infancy
- chronic hemolytic anemia
hemolysis in the presence of various oxidative stressors
WHY do premies have lower plasma oncotic pressure?
immature liver development
With increased sodium and water,
blood volume increases
with sodium and water excretion,
blood volume decreases
What primarily regulates serum osmolality?
- Renal concentrating ability
What part of the hypothalamus releases ADH to be carried to the neurohypophysis for release?
supraoptic and paraventricular nuclei
Angiotension II supports BP by: (3 ways)
- 1. Direct vasoconstriction
- 2. increased sodium and water retention (decreased GFR)
- 3. Stimulation of aldosterone secretion
At what week gestation does renal development begin?
The total # of nephrons are present at 38 weeks, and renal blood flow is 1/3 of normal
At birth, newborns have limited urine concentrating ability. What is the urine osmolality in a newborn?
Half that of an adult (1300-1400)
At year one, what are the GFR and renal blood flow compared to an adults'?
Why is hyponatremia common in the neonate?
With excess sodium loss in the urine, maintenance requirements for sodium are greater.
Why are fluid requirements high in the neonate?
- Neonates require:
- Large volumes of urine to excrete high solute concentrations
- High surface area to volume ratio
- High evaporative loss
What is the best measure of blood volume?
Lean body mass
Name the circulating blood volume ratios for premies, < 6 months, 6mo-2 years, and 2-12 years:
90ml/kg, 80 ml/kg, 75ml/kg, 72 ml/kg
90, 80, 75, 72
intracellular or extracellular water % is higher in the infant and child than the adult?
Extracellular is higher in kiddos
Why do children need to fast before surgery?
To minimize gastric contents and thus decrease risk of aspiration
The period of vulnerability is longer with inhalataional induction than IV, but is not absent with IV induction
How long before surgery can clear liquids be given to children?
This has been shown to stimulate peristalsis and reduce gastric volume and acidity.
What parameters can you assess when determining fluid volume status?
- Capillary refill
- Blood pressure
- Oxygen saturation pleth variation
- Urine Output
Minimal insensible (incisional) loss
Moderate insensible (incisional) loss
Large insensible (incisional) loss
What glucose level must be maintained to avoid neurological injury?
> 45 mg/dL
Signs and symptoms of hypoglycemia
- temperature instability
What do you give for hypoglycemia that cannot be treated orally?
2-4 ml/kg D10W followed by 4-6 ml/kg/min with BG checks q 30 minutes
When would you want an IV before induction?
GERD, trauma, full stomach, anticipated difficult airway
Which are better for rapid infusion? Longer or shorter catheters?
Shorter because longer increases resistance to flow
Complications of IO placement
- compartment syndrome
- damage to growth plates
- catheter is more easily dislodged
- onset of drugs is unpredictible
Why are isotonic fluids preferred for intraop administration?
- Most intraop losses are isotonic
- Hypotonic soln may decrease serum osmolality and cause electrolyte imbalance and fluid shifts
- Plasma volume expansion is necessary b/c loss of vascular tone d/t anesthesia
- Increases in ADH result in H2O retention in excess of sodium retention= dilutional hyponatremia
What can occur if you give 3% HTS too fast?
central pontine myelonlysis
S/S of dehydration
slow cap refill, poor skin elasticity, absent tears with crying, sunken anterior fontanelle, irritability, dry mucous membranes
Dehydration correction emergent phase
20-30 ml/kg isotonic crystalloid/colloid bolus
Dehydration correction repletion phase 1
25-50 ml/kg over 6-8 hours
Dehydration correction repletion phase 2
remainder of deficit of 24-48 hours
What dictates the treatment for hypernatremia?
neurologic status determines treatment
What may accompany acute hypernatremia?
What should you watch for during treatment for hypernatremia?
apnea, seizures, and CVR compromise
What can you give if acute hyperkalemia manifests in the OR?
Calcium Chloride- it antagonizes the cardiac effects.
At what level do we consider K to be low?
urinary dilution with plasma hypo-osmolality
Too much ADH
- hyponatremia <135 mEq/l
- serum osmolality , 280 mOmol/l
- urine osmolality > 100mOmol/l
How do we treat SIADH
- free water restriction
- Sodium replacement
decreased secretion of OR renal insensitivity to ADH
Too little ADH
What would you like to do?
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