Obstetrics Flashcards
The only respiratory parameter that does not increase or decrease during pregnancy ?
Vial capacity
Thromboxane A2 levels in preeclampsia?
DUE TO DYSFUNCTIONAL ENDOTHELIAL CELLS:
Increased thromboxane A2
+
Decreased prostaglandin I2 (prostacyclin)
=
vasoconstricted state
(Often treated with aspirin bc as a cyclooxygenase inhibitor —> thromboxane production is decreased)
pathogenesis of late decelerations?
uteroplacental insufficiency –> decreased oxygen delivery to placenta and fetus –> activation of fetal chemoreceptors –> fetal VAGAL activity stimulated (parasympathetic nervous system)
Ritodrine and terbutaline mechanism of action
Tocolytics: beta-2 > beta-1 agonists —> ATP —> cAMP —> DECR calcium —> impaired contractility —> smooth muscle relaxation
Side effects: tachycardia (beta 1 stimulation), hypotension (blood v relaxation), hyperglycemia, hypOkalemia, PULMONARY EDEMA
Late decelerations signify?
Uteroplacental insufficiency: gradual decrease of fetal heart rate AFTER peak of uterine contraction
Variable decelerations signify?
Cord compression: ABRUPT decrease in fetal heart rate NOT associated with uterine contractions
Early decelerations signify?
Fetal head compression: GRADUAL decrease in fetal heart rate that correlates with peak of uterine contraction
What is fetal scalp pH < 7.20 suggests?
Fetal acidosis
A negative fetal fibronectin test suggests?
Risk of preterm labor < 1% for one week
Most common cause of early post-partum hemorrhage?
Uterine stony (BIG/SICK/TIRED uterus)
Normal umbilical artery blood gas?
7.25/50/20
20-30-40-50 (Ua O2 - Uv O2 - Uv CO2 - Ua CO2)
Normal umbilical vein blood gas?
7.35/40/30
20-30-40-50 (Ua O2 - Uv O2 - Uv CO2 - Ua CO2)
Coagulation factors that DECREASE during pregnancy?
Most INCREASE! Fibrinogen nearly doubles.
INCREASED resistance to activated Protein C
INCREASED RBC mass
INCREASED plasma volume
Factors that DECREASE: XI, XIII, ATIII, tPA, Protein S, and platelet count
“tHINGS” that don’t cross the placenta?
Heparin
Insulin
Non-depolarizers
Glycopyrrolate
Sux
Phenylephrine
First stage of labor mediated by which dermatomes?
T10-L1: paracervical and hypogastric plexus (visceral sensation from uterus and cervix)
Second stage of labor mediated by which dermatomes?
T12-L1 (hypogastric plexus) and S2-S4 (pudendal nerve): somatic sensation from perineum and vaginal stretch
Cervical dilation to 10 centimeters is which stage of labor?
First stage
10 centimeters to delivery of baby is what stage of labor?
Second
Neuroaxial adjunct with kappa opioid agonism and local anesthetic properties?
Meperidine: extends duration of analgesia and strengthens degree of sensory/motor blockade
Blood gas in non-pregnant person versus pregnancy?
Non-pregnant: 7.4/40/100/24
Pregnant: 7.44/30/107/21
Driver for increased minute ventilation in pregnancy?
Progesterone —> TV increased more than RR
closing capacity and FRC in pregnancy?
CC>FRC especially in supine position or under GA —> leads to increased atelectasis and decreased PaO2 in a setting of INCREASED O2 consumption —> rapid desaturations
Protective factors against PDPH?
Increased age (>60)
Obesity
Men
Saline LOR technique (versus air)
Dermatome coverage needed for cerclage placement?
Cervix: T8-S4
Vagina: T10-L1
Perineum: S2-S4
What type of anesthesia preferred if “bulging membranes” during labor?
General
Normal p50 for Hb?
27 mmHg
Maternal P50 for Hb?
30 mm Hg (right shift)
Fetal p50 for hemoglobin?
19-21 mmHg (left shift)
After how many weeks in pregnancy does risk of aspiration become significant?
18 weeks
Preferred mode of anesthesia for retained placenta?
none to minimal bleeding: IV/sublingual nitroglycerin -OR- regional with minimal sedation
hemorrhaging: general anesthesia
Mode of anesthesia when uterine inversion is needed?
1st line = low-dose IV/sublingual nitroglycerin
volatiles if 1st line fails
this is a surgical EMERGENCY - must be manually reversed before cervical ring closes upon uterine fundus
Mechanism of increased atrial natriuretic peptide in response to oxytocin?
oxytocin structurally similar to vasopressin –> at doses >5 units, urine output is decreased –> volume overload sensed by atria –> atrial natriuretic peptide released –> natriuresis –> hyponatremia
Magnesium competitively inhibits which pain receptor?
NMDA
treatment for magnesium toxicity?
calcium
APGAR score requiring immediate resuscitation?
0-3
APGAR score requiring close observation and more advanced care?
4-7