OB I Flashcards
Risk factors in OB?
- Advanced maternal age
- african american race
- maternal obesity
- cesarean delivery
What is the big piece of advice Allen said in class that is always important for OB?
Always have the room prepped!
- Anesthesia services must be readily available continuously
- c-section should be started within 30 min of recognition of need
- most deahts occur during or after csection, 2x the risks compared to toher surgeries
- all patients are full stomach and are at risk for aspiration
When is RSI, application of cricoid pressure with ETT insertion necessary?
anything after 12 weeks
What is the “hallmark of successful anesthetic management of the pregnant woman”
Recognition of these changes and appropriate adaptation of anesthetic techqniques to account for them
What hormones contribute to some of the altered maternal physiology?
gastrin, relaxin, estrogen, progesteron, progestins?
- Hormonal produciton by the ovaries and placenta alters maternal physiology
- gastrin: increases gastric volume and lower pH
- Relaxan: causes relaxation of the ligamentous attachments of hte lower ribs widening, promotes lordosis, increase incidence carpal tunnel syndrome
- estrogen: nasal stuffiness, epistaxis, increase plasma renin activity, increase Na absorption and water rentetion (RAAS), increase stoke volume
- Progesterone: respiratory stimulant, smooht muscle relaxant- intestinal contractile inhibior, delays gallbladder motility, increase aldosterone (increase plasma volume)
- progestins: reduces lower esophageal sphincter tone, increase reflux
What is the mean weight gain in pregnancy? What contributes to the weight gain?
- Mean weight gain is 12 kg (26 lbs)
- uters= 1 kg
- amniotic fluid= 1kg
- fetus and placenta= 4 kg
- increase blood voluem and interstitial fluid= 2 kg
- deposition of new fat + protein= 4 kg
- 1st trimester= 1-2 kg
- 2nd and 3rd trimester= 5-6 kg increase in each
- obesity- recommended gain is less
- increase risk for adverse preganncy outcome and c-section
Recommended weight gain if BMI <18.5?
18.5-24.9?
25-29.9?
>30?
-
<18.5= 12.7-18.2 kg (28- 40 lb)
- ( RATE OF 0.45 KG/WK (1lb/week))
-
18.5-24.9= 11.4- 15.9 kg (25-35 lb)
- (rate of 0.45 kg/wk (1lb/week))
-
25-29.9= 6.8- 11.4 kg (15-25 lb)
- (rate of .27 kg/week (0.6 lb/week)
-
>30= 5-9.1 kg (11-20 lb)
- (rate of 0.23 kg /week (0.5lb/week)
CV changes in pregnancy?
- Heart size increase–> increased blood vol and increase force of contraction
- increase CO 50%
- svr decrease d/t progesterone (as well as PVR)
- HR, SV, LVEDV all up
- eccentric LV hypertrophy
- heart shift up and to the left d/t elevation of diaphragm
- accentuation of first heart sound (S1)
- Systolic ejection murmur is common
- possible S3 &S4 - no clinical relevance
- leftward displacement of PMI
- Mitral, tricuspid and pulmonic valves dilate
- aortic insufficiency would be pathologic!
- CVP, PAD and PCWP all stay normal!!!
When does maternal CO reach max value? In pregnancy or postpartum?
postpartum
What are hemodynamics like during peurperium?
peurperium= period immediately following deliver)
- CO and SV increase up to 75% of predelivery values and 150% above prepreganncy baseline
- during the next hour, CO decrease to 30% above pre-delivery (d/t decrease SV and HR)
- CO returns ot prepregnancy levels in about 2 weeks postpartum
- HR
- falls rapidly after delivery
- back to normal in about 2 weeks postpartum
- SV
- remains above prelabor values for 48 hours then begins declining
- studies ahve shownt hat anatomic (LV wall thickening) and funcitonal changes of the heart durign pregnancy are fully reversible
When is maternal cardiac output the greatest?
immediately following stage 2
What is BP affected by during pregnancy?
- age- increase age causing higher BP
- Position- left lateral position is when mom’s BP will be lowest
- parity- nulliparous have higher BP than someone that has had previous children
- Systolic, diastolic and MAP- should decrease, with diastolic decreasing the most
What is aortocaval compression?
- Decrease BP, decrease CO and impairment of UPBF (uteroplacental blood flow) caused by compression of great vessel (highest compression supince)
- Tx- left uterin deplacement (tilt mom to left via IV bag, blanket, etc)
- IV fluids
- vasopressors (ephedrine too)
- Aortocaval syndrome will cause increase in venous pressure in lower limbs
- there is collateral flow via the epidural venous plexus
What is a supine hypotensive syndrome?
- Up to 15% of term patients experience compression of the aorta when lying supine–> bradycardia and hypotension
- may take several minutes for instabilities to occur
- bradycardia is often preceded by tachycardia
- results form profound decrease in venous return
- 10-20% in SV and CO
- supine position should be avoided after 20 weeks
What is uteroplacental blood flow?
- UBF= (uterine arterial- uterine venous pressure)/ uterine vascular resistance
- UBF @ term= 500-700 mL/min
- uterine blood flow will decrease whenever perfusion pressure decreases or uterine vascular resistance increases. the uterine vascular bed lacks autoregulation because uterine arteries max dilated
- unable to dilate futher in time of hypotension/trauma
- therefore, UBF dependent on maternal BP and CO
- if mom’s BP is low, then placenta isn’t getting oxygenated enough
- no autoregulation in placenta!
What characteristics of drugs causes high rates of placental transfer?
- Low molecular weight
- small molecules
- poorly ionized- non ionized
- high lipid solubility
- low protein binding
Which anesthesia drugs have significant placenta transfer?
- IV anesthetic
- VA
- Opioids
- Benzo
- beta blocker
- magnesium
Which drugs have no transfer across placenta?
- NMB
- glycopyrrolate (robinol)
- heparin
- insulin
Respiratory changes in OB patient?
- Despite mutiple naatomic and physiologic changes during pregnancy, lung function is only slightly impacted
- AP and transver diameters increase by 2 cm
- thoracic cage circumference
- increase 5-7 cm
- vertical measurement of chest
- decrease 4 cm from the elevation of the diaphragm
- elastin causes changes
- capillary engorgmenet
- oral, nasal and larynx mucosa
- increase in nose bleeds (d/t engorgement)
- estogen related
- oral, nasal and larynx mucosa
How are lung volumes affected during pregnancy?
- TLC- down 5%
- VC- no change
- IC - increas 15%
- IRV- increase 5%
- TV- increase 45%
- FRC- decrease 20%
- ERV- decrease 25%
- RV- decrease 15%

What makes up inspiratory capacity (IC)
What makes up Functional Residual Capacity (FRC)
What makes up TLC?
IC= IRV +TV (inspriatory reserve volume and tidal volume)
FRC= ERV + RV (expiratory reseve volume + residual volume)
TLC= IC + FRC
Would we expect Pao2 to be higher in pregnancy or non pregannt?
PaCO2?
Denitrogeination achieved faster in pregnancy or non pregnant?
PAO2- higher in pregnant
PACO2- higher in non pregnant
Denitrogeination- faster in pregnancy
Other respiratory changes noted?
Why changes?
Minute ventilation?
- Dyspnea is common (75% of women)
- Increased respiratory drive
- decreased PaCO2 (causes respiratory alkalosis)
- Increased oxygen consumption from enlarging uterus and fetus
- larger pulmonary blood volume
- anemia
- nasal congestion
- minute ventilation- increase d/t progesterone
- 70-140% (1st stage of labor)
- 120-200% 2nd stage labor
What b/g state is comon pregnancy?
respiratory alkalosis



