OB Flashcards
How does pregnancy affect minute ventilation? Why? What changes are seen?
It is increased by up to 50% due to increased progesterone
Vt increases by 40%
RR increases by 10%
How does pregnancy affect the mothers blood gas? How does mom compensate for this?
Due to progesterone, she is slightly respiratory alkalotic
Renal eliminates excess bicarb which normalizes the blood’s pH
Moms;
pH?
PaO2?
PaCO2?
HCO3?
pH - no change
PaO2 - increased
PaCO2 - decreased
HCO3 - Decreased
How does pregnancy affect mom’s oxyhemoglobin dissociation curve?
Shifts it to the right - offloads O2 to the fetus
How does pregnancy affect the lung volumes and capacities?
FRC is reduced due to baby pushing up on lungs. ERV decreases more than RV
How does cardiac output change during pregnancy?
Increases by 40% - uterus receives 10% of the cardiac output
How does cardiac output change during the stages of labor?
1st - Increased by 20%
2nd - Increased by 50%
3rd - Increased by 80%
When does CO return to baseline after delivery?
Pre labor values - 24 hours
Pre pregnancy values - 2 weeks
How does BP change during pregnancy?
Net effect due to an increase in blood volume and decrease in SVR
How does SVR change during pregnancy?
Progesterone causes Increased nitric oxide which leads to vasodilation
+
Decreased response to angiotensin and NE
<15% in SVR
<30% in PVR
What is aortocaval compression? Who is at risk?
Gravid uterus compresses the vena cava and aorta in the supine position
This leads to decreased CO and compromises fetal profusion
Sign and symptom - LOC
How is aortocaval compression treated?
Displace the uterus away by elevating the right torso by 15 degrees
How does intravascular fluid volume change during pregnancy?
It increases by 35%
Plasma volume increases by 45% and RBC’s increase by 20%
Which clotting factors are increased during pregnancy?
Increased clotting factors 1, 7, 8, 9, 10, 12
Which clotting factors are decreased during pregnancy ?
11 and 13
What happens to fibrin during pregnancy ?
Decreases
Protein S and C during pregnancy?
Protein S decreaseS
Protein C - no change
What happens to MAC during pregnancy ? Why?
Decreases by 30-40% due to progesterone
How does pregnancy affect gastric volume and pH? Why?
Increases volume and decreases pH (more acidic)
Due to increased gastrin
How does pregnancy affect gastric emptying?
Before labor - no change
After labor - slowed
What is normal uterine blood flow? During pregnancy ?
Normal - 100mL/min
Pregnancy - 700mL/min or 10% of cardiac output
Does the uterus autoregulate?
It does not autoregulate there it is dependent on MAP, CO, and uterine vascular resistance
What conditions can reduce uterine blood flow?
Anything that causes decreased perfusion;
-Sympathectomy
-Hemorrhage
-Aortocaval compression
Anything that causes increased resistance;
-Uterine contraction
-Hypertension that increases UVR
Which law determines which drugs will pass through the placenta?
Ficks Law of diffusion
Drug characteristics that favor placental transfer?
-Low molecular weight <500 Daltons
-High lipid solubility
-Nonionized
-Nonpolar
What is stage 1 of labor?
Beginning of contractions to full cervical dilation
What is stage 2 of labor?
Full dilation to delivery of the fetus
What is stage 3 of labor?
Delivery of the placenta
How does uncontrolled pain affect the mother and fetus?
- Increased catecholamines which leads to HTN and reduced uterine blood flow
-Maternal hyperventilation which leads to a left shift and reduced O2 delivery
Which type of pain is felt during stage 1? Where?
Lower uterine segment and the cervix
T10-S1 posterior nerve roots
Which type of pain is felt during stage 2? Where?
Vagina, perineum, and pelvic floor
S2-S4 posterior nerve roots
What is the afferent pathway during stage 1 of labor? Which segments?
Visceral c fibers hypogastric plexus
Dull, cramping, diffuse
T10-L1
What is the afferent pathway during stage 2 of labor? Which segments?
Pudendal nerve
Sharp, localized
S2-S4
Regional technique for Stage 1?
-Neuraxial
-Paravertebral lumbar sympathetic block
-Paracervical block
Regional technique for Stage 2 of labor?
-Neuraxial
-Pudendal nerve block
Describe the needle through the needle for CSE
- Epidural needle identifies epidural space
- Spinal needle is placed through epidural needle and then LA is injected
- Spinal needle is removed
- Epidural catheter is placed
Bupivacaine vs ropivacaine; Which one is a racemic mixture?
Bupivacaine
Bupivacaine vs ropivacaine; Which one has more CV toxicity?
Bupivacaine
Bupivacaine vs ropivacaine; Which one has increased block?
Bupivacaine
Bupivacaine vs ropivacaine; Which one has low placental transfer?
Bupivacaine
Benefits of ropivacaine?
Decreased potency, CV toxicity, motor block
When giving Bupivacaine, what symptom occurs before seizures?
CV toxicity
When can chloroprocaine be used for labor?
How is chloroprocaine metabolized?
Pseudocholinesterase
How does chloroprocaine affect opioids?
Antagonizes the mu and kappa - reduces the efficacy of epidural morphine
What is one risk of chloroprocaine ?
Arachnoiditis due to preservatives
What happens if the an epidural is placed in a subdural space?
10-25 minutes the patient will experience a high block because of how small the space is, the volume spreads high
What is the treatment for a total spinal ?
Vasopressors
IVF
Left uterine displacement
Elevation of legs
Intubation
How might a total spinal occur? Injected into what space?
Subarachnoid space
Subdural space
Single shot spinal after failed epidural
What is the normal fetal heart rate?
110-160
What type of decelerations are of concerned?
Late and variable
What are early decelerations? Risk to fetal hypoxemia?
Head compression from uterine contraction
No risk of fetal hypoxemia
What are late decelerations? Risk to fetal hypoxemia?
Placental insufficiency (compressed vessels)
-Baby heart rate drops AFTER contraction
-Occurs with each contraction
What are variable decelerations? Risk to fetal hypoxemia?
Cord compression
- No consistent pattern between contractions and fetal HR
- Cord compression causes baroreceptor mediated reduction in FHR
How is premature delivery defined as?
Before 37 weeks or less than 259 days from last cycle
Complications of premature delivery ?
-Respiratory distress syndrome
-Intraventricular hemorrhage
-NEC
-Hypoglycemia
-Hypocalcemia
-Hyperbilirubinemia
How do steroids affect delivery? How long till they take effect?
18 hours with peak benefit at 48 hours
They hasten fetal lung maturity
How do tocolytic agents affect delivery ?
They stop labor and provide a bridge that allows steroids to work
What other drug is given along with tocolytic agents? To prevent what?
Antibiotic agents for chorioamnionitis
When are steroids usually given by?
Before 33 weeks
How do beta-2 agonists affect labor? What are side effects?
Prevent uterine contraction
-Hypokalemia from an intracellular K shift
-Beta-2 can cross placenta, causing increase in FHR
-Hyperglycemia
What is mom at risk for when given beta-2 agonists for preterm labor?
Hyperglycemia
Hypokalemia
Side effects of hypermagnesemia ?
Apnea
Hypotension
Skeletal muscle weakness
CNS depression
Reduced responsiveness to ephedrine and phenyl
How is hypermagnesemia treated?
Supportive
Diuretics
IV calcium
Where is oxytocin made and stored?
Hypothalamus and stored in the post pituitary gland
Side effects of oxytocin?
Water retention
Hyponatremia
Hypotension
Reflex tachycardia
Coronary vasoconstriction
What is methergine? Dose? Route? Side effects?
Erogt alkaloid
0.2mg IM (not IV)
Significant vasoconstriction, HTN, and cerebral hemorrhage
What is the most common cause of maternal death?
Failure to secure the airway
Pros to a general anesthetic?
Faster time to baby out
Secured airway
Greater hemodynamic stability
What type of aspiration prophylaxis should a patient receive scheduled for a cesarean?
Sodium citrate to neutralized acid
H2 antagonist to reduce secretion
Gastrokininetic agent that increases emptying and improves LES tone
When are pregnant women considered full stomach?
18-20 weeks
Require RSI
When and why should NSAIDS be avoided?
After the first trimester - inhibits prostaglandins
May close ductus arteriosus
HTN chart
When are moms at risk for seizures when related to HTN?
With eclampsia
When is protein in the urine when related to HTN?
Preeclampsia and eclampsia
What is the classic triad of preeclampsia ?
HTN after 20 weeks
Proteinuria
Generalized edema is no longer a requirement
What does thromboxane A2 do?
Plt aggregation
Vasoconstriction
Increased uterine activity
Decreased uterineplacental blood flow
What does prostacyclin do?
Increases uteroplacental blood flow
Decreases BP
Decreases uterine activity
Decreases platelet aggregation
What happens to the balance of prostacyclin to thromboxane in preeclampsia ?
Too much thromboxane which causes vasoconstriction
Mild vs Severe preeclampsia; BP?
Severe > 160/110
Mild vs Severe preeclampsia; urine total?
Mild - >500mL
Severe < 500mL
Mild vs Severe preeclampsia; pulmonary edema, cyanosis, headache, visual impairment, epigastric pain?
ALL SEVERE
Mild vs Severe preeclampsia; proteinuria?
Mild <5g/24 hours
Severe >5g/24 hours
How much magnesium should be given for seizure prophylaxis for preeclampsia ?
Load 4g over 10 minutes
Infusion of 1g an hour
How should an anesthetic be tailored for preeclampsia?
-Balanced fluids
-Monitor Plt
-Higher incidence of airway swelling
How does increased magnesium affect NMB?
Exhibit an increased sensitivity to them
How does magnesium affect postpartum hemorrhage?
Increases it due to magnesium relaxing the uterus
Is neuraxial anesthesia okay with preeclampsia?
Yes - recommended
How do preeclamptic patients respond to sympathomimetics and methergine
?
exaggerated response
What is HELLP syndrome?
Hemolysis
Elevated liver enzymes
Low Plt
5-10 of preeclampsia patients
Epigastric pain and upper abdominal pain
What is the definitive treatment for HELLP and preeclampsia?
Delivery of baby
Considerations if mom is a cocaine user?
Mom will have tons of NE in the synaptic cleft which increases SNS tone
Increases risk of abortion, rupture, premature labor
Careful with beta blockers
Need to monitor Plt
What is placenta accreta, increta, percreta
-uterine contractility is impaired
A- attaches to myometrium
I- Invades myometrium
P - Extends beyond uterus
GA or neuraxial for abnormal placental implantation?
Both safe but GA preferred
Possible massive blood loss
What is placenta previa? Main sign?
Placenta attached to the lower uterine segment
Covers cervical OS
Painless vaginal bleeding
What conditions are associated with increased risk for placenta previa?
Previous c sections and multiple births
What are risk factors for placental abruption?
PIH
Preeclampsia
Chronic HTN
Cocaine
Smoking
Excessive alcohol
Most common cause of postpartum hemorrhage?
Uterine atony which increased by;
Multiple fetus’s
Multiple gestations
Polyhydramnios
Prolonged oxytocin
What medication can be given with retained placental fragments?
IV nitroglycerine
What is the treatment for uterine atony?
Uterine massage
Oxytocin
Ergot alkaloids
Intrauterine balloon
What is the APGAR score?
Used to assess newborn at 1 and 5 minutes
Normal: 8-10
Moderate distress: 4-7
Impending demise: 0-3
APGAR chart
What is the best indicator of ventilation during neonatal resuscitation?
Resolution of bradycardia
Dosage for epi on a newborn?
1:10,000
10-30mcg/kg IV
0.05-0.1mg/kg intrathecal
Dosage for volume expanders in newborns
PRBCs
NS
LR
10ml/kg over 10 minutes
Vital sign chart for kids
Why is the neonates minute ventilation higher than adults?
They consume twice as much O2
Metabolically more efficient to increase rate than tidal volume
How is TV calculated for NB?
It’s the same
6ml/kg
What is the primary determinant of blood pressure in the neonate?
HR
Frank-Starling is underdeveloped
SNS vs PNS in neonate?
SNS in less mature than PNS which is why stressful situations may cause bradycardia
Baroreceptor reflex in neonate?
Poorly developed, fails to increase heart rate in hypovolemia
How do infants breathe up to months of age?
Through their nose
Tongue size in infant compared to adult?
Much larger
Neck size in infant compared to adult?
Shorter neck
Epiglottis size in infant compared to adult?
Infant have a stiffer, longer and U shaped epiglottis
Vocal cord position in infant?
Anterior slant
Larynx in adult vs infant?
Adult - C5-C6
Infant C3-C4
Normal at 5 years old
Narrowest opening in infant and adult?
Adult - Glottis
Infant - Cricoid * possibly glottis now
Best position for intubating; adult vs infant
Adult - Sniffing
Infant- head on bed with shoulder roll
Normal RR of infant?
35
Normal O2 consumption; Adult vs Infant?
Adult - 3.5 mL/kg/min
Infant - 6 mL/kg/min
Normal alveolar ventilation; Adult vs Infant?
Adult - 60ml/kg/min
Infant - 130ml/kg/min
Why do neonates desaturate faster?
Increased consumption and demand
Slightly smaller FRC
Why is an inhalation induction faster?
Smaller FRC and greater alveolar ventilation
What are type 1 muscle fibers? Type 2?
1- Slow twitch which are built for endurance and don’t fatigue?
2- Fast twitch for heavy work and tire easily
Why are neonates at risk for respiratory fatigue and respiratory failure?
Smaller number of type 1 so they fatigue faster
Compare and contrast Lung volumes
Which lung volumes are decreased in infants when compares to adults?
Infants have decreased FRC, vital capacity, and total lung volumes
Which lung volumes are increased in infants when compares to adults?
Infants have increased RV and closing capacity
Which lung volume remains unchanged?
Tidal volume
ABG of newborn
How does pH, PaO2, and PaCO2 changes during the first 24 hours for the baby
pH. 7.2 goes to 7.35
PaO2 50 goes to 70
PaCO2 50 goes to 30
How does hypoxemia affect a newborn? When does this change?
Respiratory control doesn’t mature till 44 weeks
Hypoxemia depresses ventilation till this is matured
What level does Fetal Hgb have? What is normal ?
F - 19
Adult - 26.5
Does fetal have a higher or lower affinity for oxygen?
Higher due to having 2 gamma chains instead of beta chains
2,3 DPG binds to beta chains
Indications for FFP in neonate?
Reversal of Warfarin
Correction of bleeding with elevated PT or PTT
Correction of bleeding if >1 blood volume has been replaced
What is the dose of FFP for a neonate?
10-20 ml/kg
When are Plt recommended for neonate? Dose?
Plt < 50,000
1 pack / 10kg
What happens to body temp during massive transfusion?
Hypothermia
What happens to pH during massive transfusion?
Alkalosis due to citrate metabolism in the liver
What happens to BG during massive transfusion?
Hyperglycemia due to dextrose being added in
What happens calcium during massive transfusion?
Hypocalcemia due to binding of citrate
What happens to potassium during massive transfusion?
Hyperkalemia due to older blood
How can you decrease the risk of hyperkalemia in a neonate receiving blood?
Using washed or fresh cells under 7 days
What happens to Hgb and Hct levels from birth to 12 months
Start higher then drop to below normal at 3 months then slowly come to adult levels
Estimated blood volumes? Neonate, infant, >1
neonate - 90 ml/kg
Infant - 80 ml/kg
1> year 70 ml/kg
Max EBL
When does GFR achieve maturation?
8-24 months
Infants are sensitive to dehydration and fluid overload because of this
Distribution of water
Signs of dehydration in neonate?
-Sunken anterior fontanel
- Weight loss
-Dry mucus membranes
-No tears
-Decreased skin turgor
-Lethargy
-Irritable
-Increased Hct
How should NPO fluid be replaced?
1st hour - 50%
2nd hour - 25%
3rd hour - 25%
Fluid replacement due to third spacing in neonates?
Minor; 3-4ml/kg/hr
Moderate 5-6ml/kg/hr
Major 7-10ml/kg/hr
Is glucose solutions recommended for neonates?
NO
only in prematurity, moms with diabetes, less than 48 hours old, children with diabetes
What is a normal cardiac output of a newborn? What does this mean for drugs?
200ml/kg/min
Drugs are delivered and removed at a faster rate
When do plasma levels level out for newborns?
6 months
<6 months, need less of the medication that is protein bound
How do MAC requirements change with age?
Premature - less than neonate
Neonate - less than infant
Infant 1-6 months- higher than an adult
Infant 2-3 months highest level
MAC requirements for Sevo?
0 days to 6 months - higher
6 months to 12-year-old…lower than infant but higher than adult
Dose for succ?
2mg/kg IV
4mg IM
Fastest approach for succ?
Intralingual via submental
What happens if a child receives a second dose of succ?
May cause bradycardia or asystole
If an infant laryngospasm and can’t receive succ due to MH, what drug is given?
Roc - only nondepolarizer that can be given IM
What is the most common congenital defect of the esophagus? Which class?
Esophageal atresia Type C
How is Esophageal atresia diagnosed? What does this mean?
Prevents fetus from swallowing amniotic fluid and causes increased amniotic fluid (polyhydramnios)
Unable to pass gastric tube after birth
What is VACTERL?
25-50% of patients with TEF have other anomalies
V - Vertebral defects
A Imperforated anus
C Cardiac anomalies
T TEF
E Esophageal atresia
R Renal Dysplasia
L Limb anomalies
If a patient has a type C TEF, where should the tip of the ETT be ?
Below the fistula and above the carina
If it’s above the fistula then gas will go into the stomach
How should intubation go with a patient that has TEF?
-Head up with suction
-Awake or inhalation with spontaneous breathing
- Place G tube and open to air
-Avoid positive pressure
-Precordial doppler on left side of chest —listening for r mainstem which will cause rapid desaturation
Why are neonates at risk for respiratory distress syndrome?
Might not produce enough surfactant which allows small alveoli to collapse and large alveoli to expand
Creates a V/Q mismatch and lead to hypoxemia
What test can be done in utero to assess lung development?
Amniocentesis - looking for the ratio of lecithin to sphingomyelin
L/S ratio > 2 is good
L/S ratio < 2 is bad
Where is the preductal pulse ox placed? Where is the postductal pulse ox?
Pre - Upper RE
Post- LE (either side)
What is suggested if a patient has a difference between pre and postductal values?
Pulm HTN
R-L cardiac shunt
Return of fetal circulation via the PDA
What does it mean if a patient has a hernia at the foramen of Bochdalek ?
Congenital diaphragmatic hernia which allows abdominal contents to enter the thoracic cavity
Usually on left side
S&S of congenital diaphragmatic hernia?
Sunken (scaphoid) abdomen and likely have respiratory distress
others;
Barrel chest
Cardiac displacement
Fluid filled segments
How is a patient with a diaphragmatic hernia managed?
Keep PIP <30
Avoid PVR (hypoxia, acidosis, hypothermia)
A pulse ox can be on LE and can warn of increased intra-abdominal pressure
Treatment for omphalocele? What other diseases may be present?
Surgery but less urgent
Trisomy 21
Cardiac defects
Beckwith-Wiedemann syndrome
Treatment for gastroschisis? What causes it? What are patients at risk for?
Prematurity
Surgery within 24 hours
Risk for fluid and heat loss
Need 150-300 ml/kg/day
What may occur when omphalocele or gastroschisis are closed?
Possible increased abdominal pressures which may lead to decreased systemic perfusion
May close in stages
Monitor SpO2 on LE
How and when does pyloric stenosis present? More common in males or females?
Olive shape mass above xiphoid process
Infants with non-bilious projectile vomiting
2-12 weeks of life
More common in males
Electrolyte balances with pyloric stenosis? Na, K, Cl, pH?
Vomiting depletes water and causes
Hyponatremia
Hypokalemia
Hypochloremia
Metabolic alkalosis
Anesthetic management for pyloric stenosis?
MEDICAL emergency (not surgical)
Stabilize electrolytes
Full stomach
Drop OG/NG
Liberal fluids
May be apneic postoperative due to pH remaining alkalotic
What is NEC and who is at risk?
Necrotizing enterocolitis at the terminal ileum and proximal colon
Early feeding is impaired and leads to bacterial growth and infection
Risk for bowel perforation
Premature babies are at highest risk
How is NEC treated?
Medically unless there is a bowel perforation which can lead to short gut syndrome if removed
What is retinopathy of prematurity (ROP)?
Phase 1 - inhibited growth of retinal vessels
Phase 2 - overgrowth of abnormal vessels with fibrous bands
Risk factors for ROP?
Premature/low birth weight
Hyperoxia
Mechanical ventilation
Blood transfusion
Sepsis
Vit E deficiency
How does FiO2 affect ROP?
Until retinal maturation is complete, FiO2 should be titrated between 89-94%
What is apoptosis and which anesthetics can cause this?
Programmed cell death
ALL except for opioids, xenon, and precedex
What is baby at risk for if mom is hyperglycemic?
Baby is at risk for hypoglycemia after birth due no longer having mom’s glucose supply but having baby’s insulin still circulating
