Obstetric Anesthesia Flashcards
What is the leading cause of postpartum hemorrhage?
Uterine atony
It is also the most common indication for peripartum blood transfusion.
Some of its causes are: Polyhydramnios, multiple gestations, chorioamnionitis, use of tocolytic therapy (which relaxes the uterine muscle)
Define preeclampsia (and what defines the severe type)
It is hypertension occurring after 20 weeks gestation or in the early postpartum period and returning to normal within 3 months after delivery or onset after 20 weeks gestation.
Classic triad: hypertension, proteinuria, and edema
Severe form: SBP >/= 160 mmHg, DBP >/= 110 mmHg, urinary protein > 0.5 g/24 hr, and urine dipstick 3+ or 4+
Severe form symptoms: headaches, visual disturbances, epigastric pain, RUQ abdominal pain, pulmonary edema, HELLP syndrome, or cyanosis
What factors increase the risk for postural puncture headaches?
Thin patients
Age of late teens to early 20s
A low opening pressure at the time of lumbar puncture
A history of migraines or tension headaches
What cardiac signs/symptoms should warrant further investigation in a pregnant patient?
Syncope Chest pain Severe arrhythmias Systolic murmur > grade 3 Diastolic murmur
What are normal cardiac signs/symptoms in a pregnant patient?
Soft systolic murmur
A wide loud split first heart sound
Development of a S3 heart sound
SOB palpitations dizziness edema poor exercise tolerance
What happens to serum cholinesterase activity during pregnancy?
Serum cholinesterase activity DECREASES 30% during pregnancy and remains depressed during the postpartum period.
What happens to arterial carbon dioxide tension during pregnancy?
Due to the increase in minute ventilation, there is a compensatory respiratory alkalosis which is evident on arterial blood gases as a DECREASE in arterial carbon dioxide tension
What happens to tidal volume, minute ventilation, functional residual capacity (FRC), expiratory reserve volume (ERV), Inspiratory reserve volume (IRV), closing volume, and vital capacity (VC) during pregnancy?
Tidal volume - INCREASES
Minute ventilation - INCREASES due mostly to an increase in TV
FRC - DECREASES
ERV - DECREASES
IRV - INCREASED
Closing volume - NO CHANGE
VC- UNCHANGED
What effect does Ephedrine have on fetal beat-to-beat variability
Ephedrine increases fetal beat-to-beat variability
What factors may decrease fetal beat-to-beat variability?
Sleep
Fetal hypoxia
Acidosis
Narcotics (i.e. fentanyl and meperidine)
What happens to renal function during pregnancy?
GFR rises by almost 50% as a result of the increase in cardiac output
Creatinine clearance also increases substantially from 100 mL/min in the non pregnant state to 150 mL/min in the pregnant state
What level of anesthesia is necessary to achieve with an epidural for a routine vaginal delivery? For a c-section?
Vaginal delivery: T10
C-section: T4
What spinal levels are associated with the first stage of labor? Second stage?
First stage of labor, pain fibers originate from T10-L1 associated with progressive cervical dilation and stretching of the lower uterine segment.
Second stage of labor: pudendal nerve S2-4 associated with dissension of the vaginal vault and perineum as the baby is delivered.
What medical conditions increase the risk of placental abruption?
Chronic hypertension Pregnancy-induced hypertension Pre-eclampsia Maternal cocaine use Excessive alcohol intake Smoking Prior history of abruption
How does a patient with placental abruption present?
Vaginal bleeding and uterine tenderness
What medical problem presents as painless vaginal bleeding in a parturient?
Placenta previa
What level of anesthesia is necessary to achieve with regional anesthesia in a C-section?
T4 level, which provides analgesia for the mother and abdominal muscle relaxation which makes it easier for the delivery
What drugs can produce thrombocytopenia and lupus syndrome in neonates when used in preeclampsia?
Hydralazine