Pediatric Anesthesia Pearls Flashcards
Cardiac Output is dependent on what in the pediatric patient?
HR dependent
What happens to the FRC in pediatrics?
Reduced FRC bc of reduced lung compliance & an increased chest wall compliance which yields a low residual volume at expiration. Can lead to rapid desaturation during apnea. Can lead to atelectasis & hypoxemia
Describe the left ventricle on pediatrics.
Non-compliant left ventricle leading to a FIXED stroke volume. CO extremely dependent on HR
What are the 6 main pharamacological differences in pediatrics to adults.
- Immature hepatic biotransformation
- Decreased blood protein for drug binding
- More rapid rise in FA/Fi = more rapid inhalational induction & emergence
- Increased MAC
- Large Vd for H2O Soluble Meds
- Immature NMJ
Larynx is more cephalad in pediatrics placing the glottis at what level?
C4
Obligatory nose breathers up to what age?
5 mo
What is the narrowest part of the pediatric airway up to age 5?
Cricoid Cartilage
Pediatrics can become bradycardic quickly for many causes. List some
Anesthesia, hypoxia, vagal, increased sensitivity to volatile agents & bradycardia
How to neonates attempt to regulate temperature?
Heat production is metabolized by brown fat. Neonates CANNOT shiver.
How do volatile agents affect temperature regulation in neonates?
Can inhibit thermogenesis from brown fat
Name some effects heat loss/ hypothermia have on peds
Can delay wake ups d/t decreased conduction velocity of the CNS, can cause cardiac irritability, respiratory depression, increased pulmonary vascular resistance, and alter response to medications
What nerve is responsible for inducing laryngospasm?
SUPERIOR laryngeal nerve (SLN)
IM SUX dose to treat laryngospasm
4-6 mg/kg
IV SUX dose to treat laryngsopasm
20mg IVP or 0.5-1 mg/kg
What breathing system is most efficient for spontaneous breathing in pediatrics & why?
Mapelson A because FGF can = minute ventilation thereby preventing rebreathing
In controlled ventilation, what does the minute ventilation need to be in a Mapleson A to prevent rebreathing?
3x
How does a Mapleson A turn into a Mapleson D?
Take the APL valve which is closest to the patient in Mapleson A, and move the APL valve toward the reservoir bag
What is the difference between a Mapleson D & a bain circuit?
Bain circuit is a mapelson D but has corrugated tubing for heat conservation. Caution, it can kink.
What position do you place pediatric patients in for transport & PACU?
Recovery position
What ages is postop croup most common?
1-4 yo
What are 2 meds you can give to help with postop croup?
Decadron 0.25-0.5 mg/kg
Racemic EPI 0.25
What does capillary refill provide us in the pediatric patient?
Estimate of cardiac output & intravascular volume
At what age is the pediatric HR the highest average?
8-30 days
What does the anacrotic limb of an A-line waveform tell us?
The rate of increase in pressure which relates to myocardial contractility. (More upright = increased contractility)
What does the Area Under the Curve of an A-line waveform tell us?
Pulse pressure & Stroke Volume
What does systolic time of an A-line waveform tell us?
Myocardial O2 consumption
What does diastolic time of an A-line waveform tell us?
Myocardial O2 supply
What does a short systolic time indicate?
Hypovolemia & high SVR
Marked respiratory swing in A-line indicates?
Hypovolemia, pericardial effusion + high intra-thoracic pressure (constricting heart), airway obstruction
What does a slow systolic time indicate?
Poor myocardial contractility
What percent of CO is renal blood flow (RBF)
25%
At what age is renal blood flow 1/2 that of an adult?
6mo-1yr
At what age is renal blood flow comparable/normal to adults?
3 yo
At what systolic BP are the kidneys autoregulated at?
80-180 mmHg systolic
What does nitric oxide work on in the kidneys and how?
Renal vascular tone with natural vasodilating effects
What structure in the kidneys slowly filtrates albumin?
Lamina rara interna
What structure of the kidneys slowly filters lactoperoxidase?
Lamina rara externa
What is GFR driven by?
Hydrostatic pressures
What is the largest site of the nephron for absorption?
PCT
What is the major function of the PCT of the nephron?
Sodium reabsorption
What percent of GFR is responsible for absorption in the PCT?
~50-60%
What major metabolic components play a major role of the PCT?
Na/K Pump & ATP & ANG II
Where is filtered sodium reabsorbed in the nephron?
Loop of Henle
Ascending & Descending
Where is passive solute & H20 reabsorbed in the nephron?
Descending Limb of LOH
Where is Na & Cl reabsorbed in excess of H2O in the nephron?
Thick Ascending Limb of LOH
What creates the countercurrent mutliplier mechanism of the nephron/renal system?
Tubular fluid leaving LOH is HYPOtonic (100-200 mOsm/L) + the interstitium is HYPERtonic
What components make up the countercurrent multiplier mechanism of the renal system?
LOH, cortical collecting tubules, medullary collecting tubes, respective capillaries
Where does Na reabsorption occur against a steep gradient? What is this related to?
DCT & Aldosterone
Where are K & H ions secreted in the nephron?
DCT
Where in the nephron is Bicarbonate formed?
DCT
Where in the nephron are acidic components converted to urine?
DCT
What stimulates the release & increase in Renin?
Decreased intravascular volume
Functions of Angiotensin II
- Increases sympathetic tone which increases HR, peripheral vascular resistance, and BP
- Increase/stimulates release of Aldosterone. Increases distal Na reabsorption (DCT), decreases urinary Na excretion, increases IV volume
- Increases proximal Na reabsorption at the PCT.
- Increases glomerular Efferent arteriolar resistance which increases the filtration fraction and increases Na reabsorption at the PCT.
- Increases thirst sensation and thus water consumption
- Increases cardiac contractility
What pediatric body compartment contains the most water?
Muscle @ ~75%
What fluid accounts for the majority of total body water (TBW)? & what percent? What percent accounts for total body weight?
- Intracellular fluid (ICF) @ 2/3 of TBW
- 30-40% of total body weight
What electrolytes are most abundant of the intracellular fluid?
Potassium, Phosphate, Magnesium
What makes up 1/3 of total body water and what does it contain?
Extracellular fluid (ECF). Plasma accounts for 10%.
Blood cells, PLTs, proteins
What is the estimated blood volume (EBV) of an infant?
80 mL/kg
What age range do pediatrics have maximal concentration ability (mOsm/kg) of the nephron and the same as an adult level?
1-3 yo
When is the nephron fully matured in the pediatric population?
By 36 weeks gestation
What contributes to the decreased ability to concentrate urine in infants?
Immature PCT & DCT
Slow response to mineralcorticoids
What are 2 fluid therapy concepts related to low birth weights?
Large heat loss & large insensible losses
What fluid concept contributes to rapid dehydration of pediatrics even though they do not manifest quickly?
Pediatric total body water is greater than their total body weight (higher ratio)
What intravenous fluid should be considered in pediatric patients for early caloric supplementation?
D5W
What is the blood replacement ratio in peds?
1:1
What is the crystalloid replacement ratio in peds?
3:1
Treatment of hyponatremia in peds? Restrictions & goals of raising Na concentrations?
3% NaCl
1. Only raise Na concentrations by 1 mEq/L/hr
2. Can be raised by 4-8 mEq/L if seizing
3. GOAL: 15-20 mEq/L in 48 hours
Ramifications of correcting hyponatremia too rapidly (5)
- Demyelinating lesions of pons (central pontine myelinolysis)
- Pulmonary Edema
- Hypokalemia bc increased Na and K is inverse
- Hyperchloremic metabolic acidosis (hydrogen ions)
- Transient hypotension bleeding (r/t prolonged PT & PTT)
What 2 components drive Central Diabetes Insipidus?
Hypothalamus or Pituitary
Polyuria w/ urine osmo < plasma osmo
Central DI
Diagnosis of central DI
Increase in urine osmo after administration of ADH
What are 2 medications & their doses used to treat Central DI?
- SQ or IM Vasopressin (5-10 units, q4-6hr)
- IN DDAVP (10-40 mcg/day) & has long duration (12-24h)
Medications that could result in Nephrogenic DI in pediatric patients?
Amphotericin, lithium, mannitol, ifosfamide, demeclocycline
Hallmark of nephrogenic diabetes insipidus?
Kidneys fail to respond to ADH
What is the primary cation in ICF making up 90%? How does it play in gradients?
Potassium. Gradient essential to maintain transmembrane potential
Where is 85% of potassium reabsorbed in the nephron?
PCT & Thick limb of LOH (where lasix works)
What are the “7 L’s (low) that are S/S of hypokalemia?
- Lethargic
- Low, shallow respirations… failure
- Lethal cardiac dysrhythmias (ST depression, shallow T wave, projecting U-wave)
- Lots of urine
- Leg cramps
- Limp muscles
- Low BP
What does the acronym “DITCH” stand for in hypokalemia because your body is trying to DITCH potassium?
- Drugs: loop diuretics, laxatives, glucocorticoids/hydrocortisone
- Inadequate consumption of K
- Too much water intake
- Cushing’s syndrome (causes kidneys to excrete K)
- Heavy fluid loss (NGT, V/D, wound drainage)
What are the 3 mechanism action names of the 3 classes of drugs for hyperkalemia treatment?
Membrane stabilizers, shifters, excreters
What are membrane stabilizers used in the treatment of hyperkalemia?
Calcium gluconate
Hypertonic Saline 3%
What are shifters used in treatment of hyperkalemia?
Short acting insulin (regular/humalin or novalin)
Albuterol
What are excreters used in the treatment of hyperkalemia?
Furosemide
Sodium Bicarbonate
Sodium Polystyrene Sulfonate
Which diuretic has the longest duration of action, where does it work, what is the MOA?
Spironolactone (Aldactone), DCT & collecting duct, competitive inhibitor of aldosterone
What is the MOA of furosemide?
Inhibits chloride reabsorption
