OB Anesthesia Flashcards
What are the causes of early changes in the pregnant woman?
Effects of progesterone, estrogen and prostaglandins
Increased metabolism demands of the fetus, placenta and uterus
What is the major cause of changes later in pregnancy?
Caused my mechanical displacement by the uterus
What cardiovascular changes are seen during pregnancy/
CO increases by 40%
HR increases
Blood flow increases to major organs
What organs does blood flow increase during pregnancy?
Uterus
Kidneys
Breast
Skin
What do ninety percent of pregnant develop?
Systolic ejection murmur, not pathologic unless greater than class III
What causes CO to increase during pregnancy?
Increase in chamber volume and increase in size of the ventricular wall
Why is there an increased risk of intravascular injection with regional anesthesia in pregnant women?
The extradural veins are distended
How do local anesthetic requirements change during pregnancy?
Decrease LA by 30%
Why does the both the SBP and DBP decrease slightly in the second trimester?
Due to decrease SVR, will return to baseline in third trimester
Why might EKG changes be seen during pregnancy?
The size of the heart increase by 12% and the heart is displaced up to the left and rotates laterally
What type of EKG changes may been seen with pregnancy?
Left axis deviation and ST & T wave changes in lead III
How is blood volume affected with pregnancy?
40-50% increase in plasma volume with an increased volume of distribution
Why might a pregnant patients labs show a low HH?
Hemodilution from a smaller change in blood components than plasma volume
How is clotting affected during pregnancy?
Fibrinogen and Factors VII, IX and X increase markedly
Increased in platelet count
After the second trimester, what can cause a decrease in CO?
Aortocaval compression, when the uterus compresses the aorta and IVC
What position is known to cause aortocaval compression?
The supine position
What can prolonged aortocaval compression cause?
Supine hypotension syndrome
How does supine hypotension syndrome affect the fetus?
Decreased uterine blood flow can result in fetal acidosis during labor
What are symptoms of supine hypotension syndrome?
N/V
Diaphoresis
Possible changes in cerebration
Fetal bradycardia
If a pregnant patient reports nausea while in the supine position what should be assumed?
HoTN and the provider should treat immediately
How should supine hypotension syndrome be treated?
Left uterine displacement:
Wedge under right hip
Tilting OR tabel 15-30 degrees to the left
Using a mechanical uterine displacing device
What is the thought to cause a decrease in airway resistance in the pregnant patient?
Progesterone mediated relaxation of bronchial musculature
Why do pregnant women often complain about having a stuffy nose?
Vascular engorgement of the nasopharynx, larynx, trachea and bronchi
Vocal cord changes and difficulty breathing through the nose
What is the compensatory mechanism for the diaphragm being displaced?
Increased in transverse and AP chest diameters and rib flaring due to hormonal ligament loosening effects
How much does the placenta displace the diaphragm?
4-6cm upward
What lung volumes are affected by the displacement of the diaphragm?
20% decrease in ERV, RV and FRC
However TV increased 35-50%
What position is affects the most by the decrease in chest wall compliance?
Lithotomy position
Why is a pregnant women’s PaCO2 lower than normal?
50% increase in minute ventilation
How much does O2 consumption increase in a pregnant woman?
O2 consumption increases by 20% however labor increases O2 consumption by 60%
What is the rule of thumb for choosing an ETT for a pregnant woman?
Smaller size needed 6.0-6.5
Why might the anesthetic provider choose to do a mask induction on a pregnant woman?
Inhalation induction faster due to increased MV and decreased RV
Why do pregnant women experience heart burn more frequently?
Stomach and intestines are displaced cephalic which increases intragastric pressure Stomach is more vertically positioned Angle of GE junction is changed Relaxation of the LES Delayed gastric emptying
At what point during pregnancy is a woman considered a full stomach?
All women after 14 weeks
What precautions should be taken if GA is required for the pregnant patient?
Avoid positive presse ventilation with mask anesthesia
Use RSI with cricoid pressure
What medications can be given pre-op to prevent aspiration on induction?
Bicitra
Reglan
H2 blocker
How does pregnancy affect the kidneys?
Increases the kidney size and causes the renal pelvis and ureters to dilate
How much does GFR and renal plasma blood flow increase during pregnancy?
50-60%
Why is it normal for the pregnant woman to have mild glycosuria and proteinuria?
Renal tubule reabsorption is decreased
Why do pregnant women often experience a relative fasting hypoglycemia?
Insulin secretion is enhanced and the needs of the fetus are met first
What is a normal pregnant FBG?
70mg/dL
When do signs of hypoglycemia begin to occur?
At 40mg/dL
Why might the provider give less succinylcholine if GA is required for delivery?
Serum cholinesterase levels decrease by 25-30%, lowest being 7 days post-partum
How is MAC affected by pregnancy?
MAC decreases by 25-40%, don’t have to give as much agent to achieve the desired effect
Why do pregnant women have a longer elimination half life?
Due to increased volume of distribution
How long does a pregnant woman experience altered drug responses?
Until 3 months post-partum
What are the two functions of the placenta?
Transport and Endocrine function
How does the placenta facilitate in transport?
Delivers nutrients and oxygenated blood and removes waste products
What are the endocrine functions of the placenta?
Synthesis and secretes progesterone and estrogens and takes function over from the ovaries
At term, how much CO is required for appropriate uterine blood flow?
Accounts for 10% of CO
How much uterine blood flow participates in placental exchange?
80%
What determines uterine blood flow?
Directly dependent on uterine perfusion pressure (MAP) and number and size of spiral arteries
Not autoregulated
What structure delivers 50% of uterine blood flow to the placenta bed?
Umbilical artery
What are causes of decreases in uterine blood flow?
Uterine contractions, hypertonus, HoTN/HTN, aortocaval compression and drugs that affect BP
How does the fetus receive oxygenated blood if their lungs are not functional?
Maternal blood bypasses the lungs and utilized two cardia shunts to deliver oxygenated blood?
What are the two cardiac shunts in fetal circulation?
Foramen Ovale
Ductus Arteriosis
How does fetal Hgb affect the oxyHgb dissociation curve?
Shifts the curve to the left, enhances placental oxygen uptake
What structure delivers oxygenated blood from the placenta to the fetus?
Umbilical vein
What is the average O2 sat of blood delivered via the umbilical vein?
80%
What is the average O2 sat of blood once it enters the ductus venosus?
O2 sat is 67%
What is the function of the umbilical arteries?
Two vessels that take deoxygenated blood from the descending aorta to the placenta
What can cause persistent fetal circulation after birth?
Hypoxemia and acidosis
What is the treatment for persistent fetal circulation?
Prostaglandins (for vasodilation of the pulmonary vasculature) and Mechanical ventilation
What are the five mechanisms for placental transfer?
Passive diffusion Active transport Facilitated diffusion Filtration Pinocytosis
What is the function of passive diffusion in placental transfer?
Dependent on concentration gradient and is the principle mode of drug transfer
O2, CO2, drugs and eletrolytes
What is the function of active transport in placental transfer?
Requires carrier system and energy
Amino acids and water soluble vitamins
What is the function of facilitated diffusion in placental transfer?
Also dependent on concentration gradient
Glucose
What is the function of filtration in placental transfer?
Dependent on hydrostatic or pressure gradient
Water and some solids
What is the function of pinocytosis in placental transfer?
Immunoglobulins, proteins and macromolecules
What factors determine drug concentration in the uterine artery?
Drug dose, rout of administration, maternal metabolism and excretion, maternal protein binding and maternal pH and drug pKa
What factors determine drug concentration if the umbilical artery?
Umbilical venous concentration, fetal pH, fetal protein and tissue binding, fetal hepatic metabolism and renal excretion
What drug properties affect the rate of placental transfer?
Lipid solubility
Molecular weight
Ionization
How does lipid solubility affect placental transfer?
Highly lipid soluble substances readily cross the placenta
How does molecular weight affect placental transfer?
Smaller molecules cross the placenta more easily
How does ionization affect placental transfer?
Highly ionized drugs are not going to cross as easily
What is ion trapping?
Occurs when unionized drugs cross the placenta, there they dissociate and the ionized portions will be trapped on the fetal side
What drugs frequently cause ion trapping?
Think local anesthetics
How can a provider administer a drug to mom but decrease the amount transferred to the fetus?
Administer the dug just before uterine contractions
What ethnicity and sex have the highest rate of RDS after delivery?
Young white males
What teratogenesis is associated with benzodiazepine use?
Cleft lip and palate
What teratogenesis is associated with nitrous oxide use?
Neurologic changes and hematologic changes similar to pernicious anemia
What teratogenesis is associated with cocaine?
GI and GU anomalies
When is optimal time for elective surgery during pregnancy?
The second trimester
What does the letter G represent when looking at a pregnant patient’s chart?
Gravida, meaning the number of pregnancies
What does the letter P indicate when looking at a pregnant patient’s chart?
Parity
What does the first number indicate after the letter P in a pregnant patient’s chart?
The number of term pregnancies
What does the second number indicate after the letter P in a pregnant patient’s chart?
Pre-term pregnancies (20-37 weeks)
What does the third number indicate after the letter P in a pregnant patient’s chart?
Spontaneous and elective abortions (
What does the fourth number indicate after the letter P in a pregnant patient’s chart?
Living children
What is considered the first trimeter of pregnancy?
Week 0-14 weeks
When does maternal drug intake begin to affect the fetus?
Does not affect fetus until implantation has occurred
What are the most common complaints in the first trimester of pregnancy?
Fatigue and Nausea
What is thought to cause fatigue in the first trimester?
Low BP, Low BG and physiologic anemia
What is considered the second trimester of pregnancy?
12-28 weeks
When is fetal movement usually felt?
15-18 weeks
Secretion of which hormone is thought to cause pelvic widening and gait changes?
Relaxin secretion induces biochemical changes in the cervix and ligaments loosen
When does a fetus become viable?
Greater than 24 weeks
How is the spine affected in the second trimester of pregnancy?
Lumbar lordosis increases progressively
What is considered the third trimester of pregnancy?
29-42 weeks
How might a practitioner determine gestational age once in the third trimester?
Fundal height
How much weight does the baby gain in the last month of pregnancy?
1/2 a pound per week in the last month
What is considered fetal tachycardia?
HR greater than 160bpm in term infants
What is considered fetal bradycardia?
HR less than 120bpm
What is the single best indicator of fetal well being?
Variability in fetal HR
What is considered short term variability?
Difference between 2-3 adjacent beats
What is considered long term variability?
Denotes the rough sign waves that occur 3-6 times per minute with variation of at least 6bpm
What is variability thought to indicate in a fetus?
An intact CNS regulatory mechanism
What are early decelerations associated with?
Head compression
What is considered a deceleration?
Decrease in HR low the fetal HF baseline
When looking at fetal surveillance what does an early deceleration look like on the strip?
Mirror image, the peak of the deceleration occurs with the peak of the contraction
What is the thought to cause the deceleration with uterine contractions?
Vagal discharge when the head is compressed by the contraction
What do variable decelerations indicate?
Cord compression
What is thought to cause variable decelerations when the cord is compressed?
Lack of O2, the decomposition of cerebral blood flow and O2 delivery result in a loss of fetal HR variability
What type of fetus will variability be absent?
Ancephalic fetus, why HR variability suggest the integrity of the CNS
What do late decelerations indicate?
Placental insufficiency
How might a late deceleration look on fetal surveillance?
Deceleration shifted to the right of the contraction, the lowest point of the deceleration occurs after the peak of the contraction
What is thought to cause the bradycardia in late decelerations?
O2 level in the fetal blood triggers the chemoreceptors to cause a reflex constriction of blood vessels in non vital peripheral areas so blood can be diverted to vital organs, causes HTN and stimulates baroreceptor mediated vagal response
Why are late deceleration after the contraction?
The compensatory process takes time before a result is seen
What occurs in stage 1 of labor?
Latent 0-4cm
Active 4-10cm
Transition time periods
What occurs in stage 2 of labor?
Delivery
What occurs in stage 3 of labor?
Delivery of placenta
Why might the epidural dosing change when a pregnant patient reaches the transitional stage of labor?
The pain changes from visceral to somatic
What tool can be used to determine normal labor progression?
Freidman’s Labor curves
According to Freidman’s labor curves, what is the normal amount of time it take a pregnant patient to dilate 4cm?
0-4cm takes about 8hrs
According to Freidman’s labor curves, what is the normal amount of time it take a pregnant patient to dilate from 4-10cm?
4cm hits active labor, dilate 3cm/hr until 10cm is reached
What drug is often used to augment labor?
Pitocin
What are the most common risks of using Pitocin?
Uterine rupture
Antidiuretic affect –> water toxicity
Hyper stimulation leading to fetal distress
What is a normal labor presentation of the fetus?
OA, occiput anterior
What presentation is the fetus in if it comes out face up?
OP, occiput posterior
What structures of the fetus allow for head compression as it descends in the labor canal?
Fontanels
What is a VBAC delivery?
Vaginal birth after c-section
What is a major risk factor of VBAC deliveries?
Uterine rupture
What type of uterine incisions are not allowed to have VBACs?
If it was a vertical incision
Why might a provider choose not to give a VBAC an epidural?
The patient would not know if she ruptured her uterus
How often is some form of resuscitation required at birth for the newborn?
25%
Why might newborn resuscitation be required?
Maternal reasons
Fetal reasons
Delivery difficulties
What determines resuscitation needs of a newborn?
Apgar scores
What are the five parameters of Apgar scores?
HR RR Muscle tone Response to stimulation Skin color
What is the range of Apgar scores?
0-10
Each of the five components receive a score from 0-2
When are Apgar scores assigned?
1, 5 and 10 minutes of life
What determines CO in the infant?
HR dependent, stroke volume is fixed by a noncompliant poorly developed left ventricle
What is the primary cause of cardiac arrest in neonates and infants?
Hypoxemia
What airway pressures should be used when giving breaths to a neonate that had a normal delivery?
15-20cmH2O
What airway pressure should be used on the initial breath after delivery on a neonate?
30-40cmH2O
What airway pressure should be used when giving breaths to a neonate that has diseased lungs?
20-40cmH2O
When should a provider initiate rescue breaths on a neonate?
Apnea or HR
What rate should the provider gives rescue breaths to a neonate?
40-60bpm
When should a newborn be intubated?
Prolonged bag and mask ventilation
Ineffective bag and mask ventilation
Tracheal suctioning
Severe prematurity
What is an appropriate ETT size for a newborn that is greater than 3000g
4.0 ETT
What is an appropriate ETT size for a newborn that is 2000-3000g
3.5 ETT
What is an appropriate ETT size for a newborn that is 1000-2000g
3.0 ETT
What is an appropriate ETT size for a newborn that is less than 1000g
2.5 ETT
What features of the newborn make intubation challenging?
Karge occiput can make intubation difficult, consider shoulder roll
When are chest compressions indicated in the newborn?
If after 15-30 seconds of positive pressure ventilation with 100% FiO2
HR
What is the ratio of compressions to breaths in neonatal resuscitation?
5:1
Compression rate is 10/min
What should the provider do if meconium is present at delivery?
Oral and nasopharyngeal suctioning when the infants head is delivered
How can the provider prevent meconium aspiration?
Limit stimulation and prevent crying
After the neonate is delivered, what interventions are done if meconium aspiration is suspected?
The infant is immediately intubated and suctioned
What is an ectopic pregnancy?
Implantation of a fertilized egg outside the uterine cavity
Where can an ectopic pregnancy occur?
Fallopian tubes Cervix Ovary Cornual region of the uterus Abdominal cavity
Where is the most common place for an ectopic pregnancy to occur?
The fallopian tube
What are risk factors for an ectopic pregnancy?
History of PID Previous ectopic pregnancy Hx tubal surgery Fertility drugs IUD
What are potential complications of an ectopic pregnancy?
Rupture of pelvic organ or structure
Massive hemorrhage
Infertility
Maternal death
When can methotrexate be given to treat and ectopic pregnancy?
Fetus must be less than 3.5cm
What intervention can be done for an incompetent cervix?
Cervical cerclage
What is intrauterine growth restriction?
Growth of the fetus is inhibited by a hostile intrauterine environment
What can cause a hostile uterine environment?
Maternal causes-HTN, DM, drug use
Placental causes
What are characteristics of IUGR?
Birth weight less than 10th percentile
Asymmetrical growth
Oligohydramnios
Fundal height greater than or equal to 3cm from expected
What is thought to cause intrauterine growth restriction?
Nutrition and gas exchange to the fetus is diminished, causing nutritional stores to be depleted
The blood flow is redistributed to vital organs
What are fetal complications of IUGR?
Intolerance of labor Still birth/fetal demise Temperature instability Thrombocytopenia NEC Renal failure
Why does the fetus with IUGR develop NEC and renal failure?
Preferential blood flow away from GI tract and kidneys
What can decrease the risk of breech presentation?
Incidence decreases with increasing gestational age
What are the three types of breech position?
Frank
Complete
Incomplete
Describe the Frank breech presentation.
Hips flexed with legs straight up
Describe the complete breech presentation.
Sitting indian style
Describe the incomplete breech presentation.
Feet or knees presenting
If a fetus is in the breech position how might this child be delivered?
Vaginal trial of labor
Elective C-section
External cephalic version
What conditions must be present to do a vaginal trial of labor for a breech fetus?
Fetal weight less than 3600gms
Adequate maternal pelvis
Fetal head flexed
Frank or complete breech
What are potential labor complications with a breech fetus?
Failure to progress
Umbilical cord prolapse
Fetal head entrapment
Increased maternal and fetal morbidity and mortality
What are the four types of malpresentation?
Face
Brow
Breech
Shoulder/transverse
What drugs should be available after a multiple gestation birth?
Pitocin
Methergine
Hemabate
What is considered premature rupture of membranes?
Rupture of membranes prior to 37 weeks gestation
What are complications associated with PROM?
Chorioamnionitis
Pre term labor
Fetal pulmonary hypoplasia
Umbilical cord prolapse
What is considered preterm labor?
Contractions with cervical dilation/effacement at 20-37 weeks gestation
What can contribute to preterm labor?
Infection, uterine distention, uterine anomalies, cervical compromise, placental abruption and uteroplacental insufficiency
What are possible treatment options for preterm labor?
Delivery
Tocolysis
What tocolytic agents can be used to stop preterm labor?
MgSO4
Indomethacin
Ritodrine and Terbutaline
Nifedipine
What is the mechanism of action of MgSO4 in preventing preterm labor?
Calcium channel blocker
What is the mechanism of action of Indomethacin in preventing preterm labor?
PGE inhibitor
What is the mechanism of action of Ritodrine and Terbutaline in preventing preterm labor?
Beta Sympathemomimetics
What is the mechanism of action of Nifedipine in preventing preterm labor?
Calcium channel blocker
What are complications associated with treatment of preterm labor with MgSO4?
Respiratory/CNS depression
Cardiac conduction block
What are complications associated with treatment of preterm labor with Indomethacin?
Bronchospasm (do not give to mother with asthma)
Bleeding, fetal NEC and IVH
What are complications associated with treatment of preterm labor with Ritodrine and Terbutaline?
Cardiac arrythmias or ischemia
CHF
What tocolytic agent is not typically the standard of care?
Nifedipine
What drugs can be given to accelerate fetal lung maturity?
Glucocorticoids, however must give 12hrs to be effective
What occurs in a pregnant woman who experiences abruptio placenta?
Premature separation of the placenta from the uterus
What condition is often confused with placental abruption?
Placenta previa
What is typically the clinical presentation of abruptio placenta?
Moderate to severe abdominal pain
Vaginal bleeding
Uterine contractions or hypertonus/tenderness
Fetal distress
When placental abruption occurs who is more at risk?
Fetal then maternal death
What is placenta previa?
Placental implantation over the cervical os
Why type of delivery is not possible if placenta previa is present?
Vaginal delivery
What are the four types of placenta previa?
Complete
Partial
Marfinal
Low-lying
Describe complete placenta previa.
Placenta completely covers the cervical os
Describe partial placenta previa.
Placental edge partially covers os
Describe marginal placenta previa.
Placental edge approaches cervical os
Describe low-lying placenta previa.
Located at lower half or third of uterus
What is the hallmark symptom of placenta previa?
Painless vaginal bleeding in the second or third trimester
What is the treatment for placenta previa?
Strict bedrest
Pelvic rest
Fluid resuscitation and Transfusion PRN
Tocolysis
What types of placenta previa can vaginal delivery be considered?
Marginal or partial previa with minimal bleeding
What are the tree types of abnormal placental attachment?
Placenta accrete
Placenta increta
Placenta percreta
What is placenta accrete?
Attaches directly to the myometrium
What is placenta increta?
Placenta invades the myometrium
What is placenta percreta?
Penetrates the myometrium, the worst to have
What are typically the causes of uterine rupture?
Can occur along a uterine scar
More common in multiparas
Possibly from forceps delivery or inappropriate use of pitocin
What is considered a postpartum hemorrhage?
Any bleeding that can or does result in hemodynamic instability
EBL greater than 1000mL with vaginal delivery and a 10% decrease in Hct from prenatal value
What is the most common cause of postpartum hemorrhage?
Uterine atony
What does a normal uterus do after delivery in order to avoid hemorrhage?
Contractions of the uterus compress the severed spiral arteries and venous sinuses at the placental detachment site
What are treatments for uterine atony?
Uterine massage
Have the patient empty the bladder
Pitocin infusion, Methergine, Hemabate
Why should pitocin never be given directly in an IV?
Can cause peripheral vasodilation, tachycardia and HoTN
Why should Methergine only be given IM?
Can cause HTN, vasoconstriction and increased PA pressures
What medication should not be given for uterine atony if the patient has a history of asthma?
Hemebate, it can cause bronchospasm, V/Q mismatch and hypoxemia
What is uterine version?
Occurs when the uterus flips, most common in multiparious patients
What symptoms are associated with uterine inversion?
Bradycardia due to a vagal response
Excessive hemorrhage
How should a uterine inversion be treated?
Treat blood loss
Give uterine relaxants Inhaled anesthetics, NGT and terbutaline)
Immediate uterine replacement
What is an amniotic fluid embolism?
Rare obstetric emergency in which amniotic fluid, fetal cells, hair or other debris enter the maternal circulation causing cardiopulmonary collapse
What is the pathology of an amniotic fluid embolus?
Amniotic fluid and fetal cells enter the maternal circulation
Pulmonary vessels are obstructed resulting in vasospasm, pulmonary HTN and hypoxia
What are the end organ effects of amniotic fluid embolus?
Left heart failure, decreased CO
ARDS develops
What are the classic symptoms of an amniotic embolus?
Acute shortness of breath and cough
Severe HoTN
What is the treatment of an amniotic fluid embolus?
Treatment is supportive: O2, hemodynamic, coagulopathy, steroids and CPR
What is the mortality rate of amniotic fluid embolus?
80%
When might DIC occur during pregnancy?
DIC usually occurs secondary to another disease process
shock, infection, abruptio placenta, amniotic fluid embolus, IUFD and pre-eclampsia
What causes DIC?
An imbalance between clot forming and clot lysing systems in the blood
What two labs should specifically be checked if a patient is thought to be in DIC?
Decreased fibrinogen and Elevated D-dimer and FDP/FSP
What is a hydatidiform mole?
Placental hyper proliferation without fetal tissue
What are symptoms of a hydatidiform mole?
Vaginal bleeding, hyperemesis, hyperthyroidism, absence of FHT, pre-eclampsia and ovarian cysts
What lab findings may indicate hydatidiform mole?
Hcg levels greater than 10,000 Anemia Snow storm on US Possible coagulopathy Possible lung mets on CXR
What is the treatment for a hydatidiform mole?
D&E
Start oxytocin at beginning of procedure
What are potential complications of a hyddatidiform mole?
Uterine perforation, Hemorrhage, Iatrogenic pulmonary edema, DIC and trophoblastic embolism
What end organ effects can result if iatrogenic pulmonary edema develops due to s hydatidiform mole?
HF, hyperthyroidism, dilutional anemia and pulmonary artery blockage
Where can an epidural be dosed for visceral pain in the first stages of labor?
T10-L1
Where should an epidural be dosed when the laboring patient transitions to second stage of labor and the pain changes from visceral to somatic?
Dose down to S2-S4
What are the goals for pain relief in the laboring patient?
Decreased sense of uterine contraction and fetal descent
Preservation of pressure sensation to facilitate expulsive efforts
Minimal motor block to improve effectiveness of expulsive efforts
What makes NO2 effective in brief analgesia during labor?
Increased sensitivity
What block can be done for pain relief in stage one of labor?
Paracervical block
What block can be done for pain relief in stage two of labor?
Peudundal block
What is a complication of a paracervical block that will need to be monitored for when administering?
Profound bradycardia
What IV analgesic are preferred in the laboring patient?
Stadol and Nubain
What is the mechanism of action of most epidural adjuvants?
Alpha 2 agonists with activate inhibitory pathways
What CV effects do epidural/intrathecal analgesics have on the pregnant patient?
Veno and arteriodilation, decreased venous return and decreased after load
HoTN with reflex tachycardia
Bradycardia (T4) with high block
If prolonged HoTN occurs with epidural placement what can happen to the fetus?
Acidemia
What is the primary concern of the fetus when opioids are given to mom?
Primary concern is sedation and respiratory depression from opioids
What opioid is unsatisfactory for the second stage of labor when administered intrathecally?
Morphine
What are side effects associated with intrathecal opioids?
Respiratory depression
Urticaria
Nausea and vomiting
Urinary retention
What are intrathecal opioids are most commonly used for the pregnant patient?
Fentanyl
Sufenta
Duramorph
Meperidine
Which opioids have the fastest onset when given intrathecally?
Fentanyl and Sufenta
Which intrathecal opioid has the highest incidence of nausea and motor blockade?
Meperidine
What are the benefits of using LA with opioids for laboring analgesia?
No weakening of maternal power, no alteration of maternal assumes and no depression of the passenger
What is the most frequent combination of LA with opioids in the laboring patient?
Isobaric bupivicaine 2.5mg with 20-25mcg Fentanyl or 10-15 of sufenta
How much LA is required for a saddle block?
Lidocaine 30-35mg
Tetracaine 3mg
Bupivacaine 7.5mg
Which LA isn’t used in the labor patient due to its high likelihood of ion trapping?
Mepivacaine
What is the benefits of using a vasoconstrictor in intrathecal anesthesia?
Potentiates lidocaine and tetracaine, use with caution in maternal HTN
What determines epidural level and duration?
Dose, volume and concentration of LA
Presence or absence of epinephrine
What opioids can be used for a laboring epidural?
Fentanyl
Sufenta
Duramorph
What is typically the rule of thumb of onset and duration of LA for epidural anesthesia?
The faster the onset, the shorter the duration
What is a segmental block?
Intermittent injections to isolate specific segments
What are the benefits of utilizing a complete epidural block compared to a segmental block?
More stable depth of analgesia
Lower risk of complete spinal wth continuous
Lower incidence of HoTN
Low risk of blood concentrations if migration of catheter occurs
What level block should be achieved before initiating continuous epidural infusion?
T10-L1
How often should the provider check on the patient an epidural has been placed?
Always check level carefully for the first 30min then hourly rounds on the patient to ascertain VS and level of block
What intervention should be completed immediately if a patient complains of nausea after an epidural has been placed?
Treat for HoTN immediately
How can an epidural affect labor?
Can slow or stop progression
Disrupt uteroplacental perfusion secondary to HoTN
Fetal hypoxia/asphyxia
When should the provider advance the epidural catheter in order to avoid intravascular placement?
Thread catheter in between contractions
What are characteristics of a PDPHA?
It is positional (worse when sitting up), frontal to occiput, visual disturbances, nausea and time
What are treatments for a PDPHA?
Bedrest
Fluids
Caffeine
Epidural blood patch
What neurological complication can be caused from exertional effort of labor causing spinal root compression?
Prolapsed intervertebral disk
What neurological complication can be seen during labor if the patient develops foot drop, hypothesis of foot and calf, and quadriceps weakness?
L4-L5 compression from descending head or use of forceps
What neurological complication can be sen during/after labor if the patient develops knee problems and quadriceps paralysis?
Femoral nerve L2-4 injured from lithotomy position
What neurological injury can be seen during labor that may cause transient numbness of thigh?
LFC L2-L3 injured during lithotomy and c-section
What neurological injury can be seen during labor that causes pain that radiates from gluteal to foot and inability to flex the leg?
Sciatic nerve L4-S3 can be injured during lithotomy
What neurological injury can be seen during labor that can cause weakness or paralysis of thigh adductors?
Obturator L2-L4 injured with lithotomy position
What neurological injury can be seen during labor that contributes to the loss of ability to assume the erect position with foot drop?
Common Peroneal Nerve L4-S2 injured during lithotomy position due to prolonged compression of lateral aspect of knee
What neurological injury can be seen during labor that causes a loss of sensation over the medial aspect of the foot and anterimedial aspect of the lower portion of the leg?
Saphenous Nerve L2-L4 injured during lithotomy position
What is the goal level of blockade for a patient undergoing a c-section?
T4 Level
What anesthetic techniques can be preformed for a patient undergoing a c-section?
Regional: subarachnoid or epidural
GA
What complication can occur when laying a patient flat for a c-section?
Aortocaval compression, left uterine displacement
What is the most common LA used in spinal anesthesia for a c-section?
0.75% bupivacaine in 8.5% dextrose
less than 65 minutes 1.4mL (10.5mg)
Greater than 65min 1.6mL (12mg)
What are complications associated with spinal anesthesia for a c-section?
Post dural puncture headache Total Spinal Anesthesia LAST Neurological injury Respiratory depression
What is typically the LA of choice for epidural anesthesia?
Bupivacaine 0.5%, dose 5mL at a time, 20mL usually gives a T4 level
What medication can aid in speed of onset?
NaBicarb to increase speed of onset, give 5mL aliquots
What percentage of Lidocaine is used for epidural anesthesia?
2% compared to 5% used in spinal anesthesia
What LA can be given if onset of epidural is needed quickly?
Chloroprocaine 3%
Why is it essential that the provider uses 0.5% Bupivacaine as opposed to 0.75% for epidural anesthesia?
Cardiac toxicity especially in pregnant individuals
Why might a lot of providers avoid using 2-chloroprocaine for laboring epidurals?
There used to be a preservative that caused arachnoiditis
Why its a caudal block used very often for a laboring patient?
Accidental placement of needle in the baby’s head
Why is maternal awareness so common in GA?
Midazolam is not given due to effects on fetus
What are complications associated with GA in the pregnant patient?
Maternal aspiration
Maternal awareness
Airway management
Why do pregnant women desaturate more quickly?
Increased O2 consumption and decreased FRC
What is gestational diabetes?
During pregnancy, maternal glucose levels are low at 70-120mg/dL as the fetus continuously draws from maternal supplies
What is the goal in treatment of gestational diabetes?
To replicate theses low maternal glucose levels
What is significant about glucose and insulins regulation from mom to baby?
Glucose crosses the placenta, but insulin does not
How does GDM affect the fetus?
Mothers blood brings more glucose to the fetus
Fetus makes more insulin to handle the extra glucose
Extra glucose is stored as fat and fetus become larger than normal
What is GDM often associated with?
Birth defects and structural malformations, CV being most common
What birth trauma may occur from GDM?
Shoulder dystocia and Brachial plexus injury
What are fetal complications from GDM?
RDS since lung maturity is delayed Fetal demise Hyperbilirubinema Hypoglycemia for excessive insulin production when receiving maternal glucose (potential for seizures, coma and brain damage) Childhood/adolescent obesity
What complication can affect mom in GDM?
Miscarriage
HTN
Pre-eclampsia
C-section
How is GDM diagnosed?
Screen all patients less than 28 weeks gestation:
1hr glucose challenge
3hr glucose tolerance is 1hr is abnormal
How is GDM treated?
Supplemental folic acid (decreases neural tube defect)
Tight glucose control, especially 3rd trimester
Intensive fetal surveillance
What are the two types of GDM?
Diet controlled diabetics
Insulin dependent diabetics
How are GDMA1 patients managed in labor?
No glucose containing IVF
How are GDMA2 patients managed during labor?
Ascu checks Q1-2hrs, sliding scale coverage
May require insulin infusion, .5-1u/hr with D5LR at 100mL/hr
What are the four categories of HTN associated with pregnancy?
Gestational HTN
Pre-eclampsia
Chronic HTN
Chronic HTN with superimposed pre-eclampsia
What is pre-eclampsia?
Occurs after the 20th weeks of pregnancy
Triad of symptoms:
Labile HTN
Proteinuria
Non-dependent edemaWhat differentiate pre-eclampsia from eclampsia?
Once seizure activity results the patient is now said to have eclampsia
What is considered HTN for pre-eclampsia?
SBP > 140mmHg
DBP >90mmHg
This must occur on two separate readings greater than 6hrs apart
What is considered proteinuria for pre-eclampsia?
Greater than 300mg protein in 24hrs
Greater than 2+ protein on dip stick
What is thought to cause pre-eclampsia?
Unknown, however theory that it is related to decreased placental perfusion and uteroplacental ischemia
How would uteroplacental ischemia contribute to causing pre-eclampsia?
Uteroplacental ischemia leads to production and release of biochemical mediators into the maternal circulation
Biochemical mediators cause: arteriolar constriction and vasospasm, vascular endothelial dysfunction
What are CV effects of pre-eclampsia?
Labile HTN
Vascular leakage of fluid and protein
Decreased colloid osmotic pressure
Decreased intravascular volume
EdemaWhat is considered severe pre-eclampsia?
SBP >160mmHg
DBP > 110mmHg
How does pre-eclampsia affect the pulmonary system?
Upper airway edema and if severe enough can lead to pulmonary edema
What effects does pre-eclampsia have on the blood?
Hypercoagulable
Hemoconcentrated
DIC
What is the most common complication of pre-eclampsia on the hematologic system?
Thrombocytopenia
How does pre-eclampsia affect the kidneys?
Proteinuria
Low urine output
Decrease uric acid clearance
What effects does severe pre-eclampsia have on the kidneys?
Oliguria and Renal failure
How does pre-eclampsia affect the liver?
Impairs function resulting in elevated LFTs
What are complications to the liver from severe pre-eclampsia?
Swelling of the liver capsule
Liver necrosis
Sub capsular hematoma
What symptom is usually associated with swelling of the liver capsule?
Epigastric pain often felt in the left upper quadrant
Why should epinephrine be avoided in epidurals for patients with pre-eclampsia?
Can cause vasoconstriction or increase the patients BP even more making their condition worse
What are CNS effects of pre-eclampsia?
HA and Hyperreflexia
What CNS effects are often associated with severe pre-eclampsia?
Visual disturbances
Cerebral edema
Cerebral hemorrhage
Maternal death
How can severe pre-eclampsia affect placental perfusion?
Cause infarction or abruption
What is the definitive treatment for pre-eclampsia?
Delivery of the fetus and placenta
How should we expect pre-eclamptic patients to be medically managed?
Control of HTN
Anticonvulsant prophylaxis
Maintenance of renal function
Determining fetal lung maturation
What drugs can be used to treat pre-eclamptic HTN?
Magnesium sulfate
Hydrazine
Labetalol
What drugs can be given to pre-eclamptic patients for seizure prophylaxis?
Phenytoin
Midazolam/Diazepam
Nifedipine
Nitropresside
What is the anticonvulsant of choice in women with pre-eclampsia?
Magnesium sulfate
What are the effects of MgSO4 on eclamptic seizures?
Antagonizes the calcium channels in smooth muscle cells
Vasodilates ans increases uterine blood flow
Decreases Ach release at the neuromuscular junction
What are therapeutic serum levels of MgSO4 on therapy for seizure prophylaxis?
4-8mEq/L
What are adverse affects of MgSO4 use?
Respiratory depression
CNS depression
Cardiac conduction block
What are signs of MgSO4 toxicity?
Respirations less than 12
Absent deep tendon reflexes
Skeletal muscle weakness
What is the treatment of MgSO4 toxicity?
10-20mL of 10% calcium gluconate
How should the provider consider dosing paralytics if a patient requires GA for an emergent delivery on MgSO4?
Decrease NMBAs, MgSO4 decreases endplate sensitivity to Ach motor end plate release
Why might a patient be placed on a uterotonic drug while on MgSO4 for seizure prophylaxis?
MgSO4 decreases uterine tone
What is the goal of HTN treatment in the pre-eclamptic patient?
DBP 90-100mmHg
What is the antihypertensive of choice in patients with pre-eclampsia?
Hydrazine, it vasodilates arterioles and increases HR, increasing CO and improving placental blood flow
When do majority of eclamptic seizures occur?
Occur prior to delivery
25% prior to the onset of labor
50% occur during labor
What are typically the characteristics of seizures by eclamptic patients?
Tonic-clonic, lasting 60-70sec, followed by a post-ictal phase
Why is GETA usually elected for emergent delivery after an eclamptic seizure?
Thrombocytopenia/coagulopathy contraindicated regional anesthesia
Airway is secured
When might vertical transmission of HIV occur from mother to child?
Prenatally
Intrapartum (most common)
Breastfeeding
What are the two routes of fetal HIV infection prenatally?
Hematological across the placenta
Across the amniotic membranes
When does most vertical HIV transmission occur?
During delivery, contact with maternal blood and cervicovaginal secretions
Transmission rate increases with time and amount of neonatal exposure
What is the delivery method of choice to prevent HIV transmission?
Elective c-section prior to ROM
