Obstetrical anesthesia Flashcards
Case fatality rate of general anesthesia in pregnant women over neuraxial anesthesia?
17%
Preeclampsia is considered severe if accompanied with? (3)
- Proteinuria
- Severe hypertension
- End-organ damage
Leading cause of maternal mortality worldwide?
Antepartal hemorrhage
Leading non-obstetric cause of maternal mortality?
Heart disease
3 most common heart conditions related to pregnancy changes:
- PACs
- Paroxsymal SVTs
- Ventricular arrhythmias
How many degrees of tilt for left lateral decubitus?
15
What hormone induces increase in minute ventilation?
Progesterone
Reduction of partial carbon dioxide pressure by? mmHg
And increase of oxygen by?
32 mmHg
106 mmHg
What causes development of hypoxemia during periods of apnea? (2)
- Decreased FRC
2. Increased metabolic rate
What predisposes toward hyperglycemia and ketosis? (2)
- HPL
2. Cortisol
Describe the Fick principle and where is it used?
Q/t = KA (Cm-Cf)/D
Q/t: rate of diffusion K: constant A: surface area Cm: free drug (maternal) Cf: free drug (fetal) D: thickness of diffusion barrier
3 principles that drugs can cross placenta easily
- Smaller (<500 Da)
- More lipid soluble
- More ionized
There is only one drug that is metabolized in the fetal blood so rapidly that even in acidosis, substantial accumulation in the fetus is avoided.
2-chlorprocaine
True or false?
Elimination half-life is prolonged in the newborns due to a greater volume of distribution of the drug
True
A drug which has been implicated as a possible cause of neonatal jaundice because of its high affinity for fetal eruthrocyte membranes may lead to a decrease in filterability and deformability, redering them more prone to hemolysis.
Bupivacaine
Pain during labor are carried by what type of fibers?
Visceral afferent type C fibers
During the first stage of labor, pain is referred to what range of segments?
T10 - L1
During the late first and second stages of labor, additional pain impulses from distention of the vaginal vault and perineum are carried by the pudendal nerves composed of what range of segments?
S2 to S4
3 most frequently chosen methods for relieving pain of parturition?
- Psychoprophylaxis
- Systemic medication
- Regional anesthesia
Meperidine side effects on the FHR (2)
- Decreased beat to beat variability
2. Mild tachycardia
Most common complication of central neuraxial block?
Hypotension
Prolonged time of the 2nd stage of labor for how many hours in nulliparous? multiparous?
3 hour
2 hours
Effective epidural anesthesia may be achieved by blocking sengments? range
T10 to L1
Analgesia volumes for
1. Bupivacaine or Ropivacaine (0.125%)
Maintenance (8 to 12 mL/hr) concentrations
- Bupivacaine
- Ropivacaine
- 5 to 10 mL
- (0.0625% to 0.1%)
- (0.08 to 0.15%)
Most commonly used inhalational agent for analgesia during labor
Nitrous oxide 50%
Most commonly used local anesthesia for spinal block
Bupivacaine 0.75% (12.5 to 13.5 mL)
Surgical anesthesia for 90 to 120 minutes
Intrathecal morphine will provide anesthesia fro how many hours?
12 to 18 hours
In denitrogenation, how many breaths must be performed to prevent hypoxemia?
4 breaths with 100% O2
Cause of epigastric pain in preeclampsia
Subcapsular hemorrhage of the liver
Mainstay of anticonvulsant therapy in eclampsia
Magnesium sulfate (LD: 4g in 20% solution in 5 mins) (MD: 1 to 2 g/H)
Most commonly used vasodilator in preeclampsia
Hydralazine
Ideal in the treatment of hypertensive emergencies
Nitroprusside
Leading cause of cesarean hysterectomy
Placenta accreta
Predisposing factors to uterine atony (8)
- Multiple gestation
- Labor induction
- CS
- Polyhydramnios
- Chorioamnionitis
- Retained products of conception
- Hpn disorders of pregnancy
- Antepartal hemorrhage
Cardiac decompensation in patients with heart disease commonly occurs during (3)
- 3rd trimester of pregnancy
- Labor and delivery
- Immediate post partum period
- Condition which occurs when uncorrected, left to right shunt results in pulmonary hypertension, which when severe, reverses flow to a right to left shunt.
- What anesthetic plan is suitable for cesarean delivery?
- Eisenmenger’s syndrome
2. General anesthesia
_______ which occurs in 10% of pregnant women, occurs because the supine position leads to vena cava occlusion and thus decreased preload to the heart, resulting in lowered cardiac output and blood pressure, tachycardia, maternal mental status changes, nausea, and presyncope.
Supine hypotensive syndrome
What hormone causes the increase in minute ventilation?
Progesterone
Ventilation returns to normal within?
1-3 weeks
What hormone decreases the tone of the LES during pregnancy?
Progesterone
RSI is recommended starting what how many weeks AOG?
20 weeks
What nerve increases susceptibility to lidocaine block?
Median nerve
Drugs cross biologic membranes by simple diffusion, the rate of which is determined by what principle?
Fick = Q/t = KA(Cm − Cf )/D
where Q/t is the rate of diffusion, K is the diffusion constant, A is the surface area available for exchange, Cm is the concentration of free drug in maternal blood, Cf is the concentration of free drug in fetal blood, and D is the thickness of the diffusion barrier
- smaller molecular size (<500)
- more lipid soluble
- Less ionized
What sizeof molecules can cross the placenta?
< 500 Da
What is the first fetal organ perfused by the umbilicous blood?
Liver
Because of this unique pattern of fetal circulation, continuous administration of anesthetic concentrations of nitrous oxide during elective cesarean sections caused newborn depression only if the induction-to-delivery interval exceeded?
halothane, enflurane,and isoflurane?
5 to 10 minutes
1 minute
What metabolite in meperidine causes neonatal depression?
Normeperidine
A nerve derived from the lower sacral nerve roots
(S2 to S4), supply the vaginal vault, perineum, rectum, and parts of the bladder
Pudendal nerve
Blockade of what dermatome is necessary for cesarean section?
T4
The most common complications of neuraxial anesthesia is?(2)
Hypotension
Decreased uteroplacental perfusion
Leading cause of maternal death related to anesthesia
Inability to intubate the trachea and provide effective ventilation
Usual blood loss during cearean delivery is?
750 to 1,000 mL
How much coloading should you give (crystalloids)?
Colloids?
1,000 to 1,500 mL
500 mL
Amount of caffeine IV and oral to decrease PDPH?
IV: 500 mg
Oral: 300 mg
Amount of blood patch to decrease PDPH?
20 mL
Most symptoms of pre-eclampsia may result from an imbalance between?
Prostacyclin and thromboxane
______is central to the development of preeclampsia and occurs as a result of reduced placental perfusion and a production and release of substances (possibly ____ )
Endothelial injury
Lipid preoxidases
Placental ischemia results in a release of uterine ___and an increase in ______?
renin and angiotensin
In preeclampsia, there is believed to to have a decreased production of ____, secreted in the trophoblast, which normally would balance the hypertensive effects of the renin–angiotensin system.
Prostaglandin E
The mainstay of anticonvulsant therapy is?
magnesium sulfate
intravenous loading dose of 4 g in a 20% solution over 5 minutes
Most commonly used vasodilator in preeclampsia?
Hydralazine
A condition when extravasated blood dissects between the myometrial fibers
Couvelaire uterus
Stillbirth likely occurs when placental separation is at how many %?
> 50%
Pulmonary hypertension has a mean pulmonary pressure over ____ at rest or ___ with exercise.
25 mmHg
30 mmHg
Maternal mortality from primary pulmonary hypertension is due to?
Right heart failure
Cardiomyopathy of pregnancy is?
Left ventricular failure
Left ventricular failure with
25%
MI in pregnancy: artery usually affected?
Left anterior descending artery
Guidelines for management of pregnant diabetics focus on?
Glycemic control
A blood sugar of _____ is desirable and insulin therapy is needed if fasting blood sugar levels are _____
60 to 120 mg/dL
>100 mg/dL
Preterm infants with breech presentation are usually delivered by cesarean as are very lowbirth-weight infants (<1,500 g). If neuraxial anesthesia is used, _____ should be available for uterine relaxation.
If vaginal delivery occurs with a breech infant and there is head entrapment, _______ may be needed for uterine relaxation.
nitroglycerin
general anesthesia or nitroglycerin
There is compelling interest to prevent vertical transmission of HIV from the mother to the fetus. The risk of intrauterine infection is: %
4.4 %
Intrapartum transmission accounts for ___ % of the risk of peripartum transmission and the remainder is through _________.
60%
breastfeeding
_____is the most commonly abused substance in pregnancy.
Smoking
Smoking is protective in the development of what condition in pregnancy?
Preeclampsia
How much alcohol consumption does the mother take to develop fetal alcohol syndrome?
> 3 oz of absolute alcohol per day
Neurobehavioral deficit and IUGR have been demonstrated in infants of moderate drinkers (___ oz/day)
102
‘Electric fetal monitoring: During the active
phase, contractions should occur every ____ minutes, with peak intrauterine pressures of _____ mmHg and resting pressures of _____ mmHg.
2 to 3 minutes
50 to 80 mm Hg
5 to 20 mm Hg
Normally, contractions occur at a rate of ______ in ____ minutes.
five contractions in 10 minutes
To rule out esophageal atresia, a suction catheter is inserted into the stomach. Gastric contents are aspirated; volume in excess of ___ mL after vaginal delivery and ___ mL after cesarean delivery may result from an abnormality of the upper gastrointestinal tract.
12 mL
20 mL
The 2 most common indications for EXIT procedure?
- Large fetal neck masses
2. Reversal of tracheal occlusion
The most frequent nonobstetric procedures are (4)
- excision of ovarian cysts
- appendectomy
- breast biopsy
- surgery related to trauma
Teratogenic effect of high doses of diazepam
Cleft palate
A fall in maternal mean arterial pressure >___ mm Hg decreases uterine blood flow.
25
Placental transfer is accomplished by
- Simple diffusion
- Active transport
- Bulk flow
- Facilitated diffusion
- Breaks in the chorionic membrane
What are most commonly used for obstetric
epidural analgesia local anesthetic?
Bupivacaine (most common)
Ropivacaine
What is the safest of the commonly used local anesthetics for labor.
Chloroprocaine
The therapeutic range of magnesium sulfate is?
4 to 8 mEq/L
With hypomagnesemia, deep tendon reflexes are absent at what range?
10 mEq/L
With hypomagnesemia, sinoatrial block and
respiratory paralysis occur when concentrations are at?
15 mEq/L
With hypomagnesemia, cardiac arrest occurs at?
25 mEq/L
Magnesium toxicity is treated with?
Calcium
What is the most common coagulopathy in preeclampsia?
Thrombocytopenia