Pediatric Anesthesia Week 2 Flash Cards
What is the normal hemoglobin and hematocrit (H&H) for a neonate?
Hemoglobin: 18- 19 grams/dL
Hematocrit: 60 %
At birth, what is the percentage of hemoglobin is fetal hemoglobin?
50- 70%
How does fetal hemoglobin (HgbF) different from adult hemoglobin (HgBA)? How does it affect its Oxyhemoglobin Dissociation Curve?
Fetal hemoglobin (HgBF) has a higher affinity for oxygen, picking up more oxygen, but does not deliver it to the tissues. HgBF holds on to O2 not delivering it to the tissues, thus SHIFTING curve TO THE LEFT
At what age does H&H change in infants? How?
Around 2- 3 months. H&H DECLINE steadily. Hemoglobin declines to 9- 11 grams/dL and HgBF is largely replaced with HgBA
When does HgBA start to increase? At what level? At what age does HgBA normalize?
- After 3 months
- HgBA: 12- 13 grams/dL
- Usually at or around puberty
How does a preterm neonate’s H&H transition from HgBF to HgBA? Or does it?
It occurs EARLIER and has a more PRONOUNCED DECREASE in hemoglobin
How much does a preterm neonates hemoglobin decrease when transitioning from HgBF to HgBA?
Decreases to about 7- 8 grams/dL
How does a preterm neonate’s drop in hemoglobin affect its Oxyhemoglobin Dissociation Curve?
Despite the reduction of HgB, the O2 delivery to the tissue may not be compromised due to the curve SHIFT TO THE RIGHT (more HgBA)
At what age does hemoglobin “normalize” (comparable to full-term neonates) in preterm neonates?
At or about 1 YEAR of AGE
Is the Oxyhemoglobin Dissociation Curve of a newborn shifted to the LEFT or RIGHT? Why?
- LEFT (more HgBF vs HgBA)
- HgBF does not bind with 2, 3 DPG, shifting the curve to the LEFT
How is HgBF beneficial to a fetus?
Allows the loading of more O2 at lower fetal O2 partial pressures (fetal arterial PO2 of 20- 30 mmHg)
What happens to the Oxyhemoglobin Dissociation Curve during the first few months of life? Why?
- It TRANSITIONS to a SHIFT TO THE RIGHT
- As HgBF is replaced by adult HgBA (2-3 or 3-4 months) decreasing levels of 2, 3 DPG increasing the infants P50 enhancing O2 delivery, shifting curve TO THE RIGHT
What are the Dubowitz & Ballard scoring system?
- A means of estimating GESTATIONAL AGE
- Dubowitz: external score using physical characteristics with neurologic score
- Ballard: uses simplified scoring criteria
When are the systems MOST ACCURATE? When are they not?
- 30- 42 hours AFTER delivery
- In very small, preterm neonates
What is the most accurate means of assessing gestational age?
By measuring the CROWN-RUMP LENGTH OF THE FETUS during the FIRST TRIMESTER during ultrasound
What is the hemoglobin concentration at 2 weeks? 2- 3 months of age? 2 years of age?
- 2 weeks: 13- 19 grams/dL (100 ml of blood)
- 2- 3 months: LESS than 10- 11 grams/dL
- 2 years: LESS than 12.5 grams/dL
What is the NORMAL range for hemoglobin level in a FULL-TERM newborn?
14 to 19 grams/dL
What happens to the Hgb of a FULL-TERM newborn after birth? What happens to the hematocrit?
- It transitions from HgBF to HgBA and at 2-3 months (9th to 12th week) it “bottoms out” to a minimum of 10 to 11 grams/dL
- Hematocrit drops from 60% to around 33%
When does hemoglobin levels START to stabilize in a FULL-TERM newborn?
Usually after the 3rd month (12th week) until about 2 years of age
When does hemoglobin normalize to adult levels? What are normal adult hemoglobin levels?
- Begin to rise after 2 year of age and normalize at puberty
- Adult HgB: 14.0- 15.5 grams/dL
How does a hemoglobin levels differ in the PRETERM vs the FULL-TERM neonate?
- In PRETERM, HgB transitions EARLIER and DECREASE MORE (around 7 to 8 grams/dL by 4 to 8 weeks)
- PRETERM neonate’s transition catch up to their FULL-TERM counterparts at or around 1 year of age
What is the minimum hemoglobin concentration necessary before O2 carrying capacity is jeopardized in a neonate? An infant older than 3 months?
- Neonate: LESS THAN 13 grams/dL
- Infant > 3 months: LESS THAN 10 grams/dL
A 3 month old infant, scheduled for surgery, has a HgB of 10.5 grams/dL. What action should be taken?
Continue with the surgery as it is > 10 grams/dL and the infant is 3 months of age (normal: 10- 11 grams/dL)
During pre-op of a 6 month old infant, you note physiologic anemia. What is the likely cause?
Most likely a FORMER PREMATURE INFANT (ex-premie). They tend to remain anemic because of poor nutrition and delayed hematopoiesis, induced by earlier transfusions
*Tend to catch up with full-terms at 1 year of age
In fetal circulation, PVR is ________ and SVR is _________.
- Increased
- Decreased
In fetal circulation, the Foramen Ovale connects the ________ with the _________. Shunting blood from ________ to _________.
- Right Atrium
- Left Atrium
- Right
- Left
How does the Foramen Ovale naturally close?
The transition of pressure with the SVR increase and PVR decrease changes the direction of shunt from fetal R to L shunt to a normal L to R shunt, thus closing the flap over the Foramen Ovale
What factors close the Ductus Arteriosis and Foramen Ovale?
- PRESSURE CHANGES within the two circulations and REDUCED levels of PROSTAGLANDINS
- DECREASE in PVR w/ CONSTRICTION of Ductus Arteriosis s/t Oxygenation
- Increase in pulmonary blood flow
What factors may cause a neonate/infant to return to fetal circulation?
- Preterm neonates/infants
- Metabolic derangement (asphyxia, sepsis, meconium aspiration, congenital diaphragmatic hernia)
What 4 factors precipitate persistant fetal circulation in neonates?
- Hypoxemia
- Acidosis
- Pneumonia
- Hypothermia
What is the pathologic mechanism common in persistent fetal circulation?
Increased pulmonary vascular resistance (PVR) leading to R to L shunting
What does ASD stand for? What is it?
- Atrial Septal Defect
- “Hole” within the atrial septum (between RA and LA)