Obstetrics (part 1) Flashcards
EBL in a pregnant woman
90cc/kg
Twin gestation EBV
105cc/kg
Blood volume is _____ in pregnancy.
Blood volume increased in pregnancy….calculations used for C/S, esp. will affect ongoing blood loss
Blood loss for different delivery types
Average blood loss vaginal delivery is 400-500cc
Average blood loss C/S 800-1000cc
Average blood loss twins by C/S-1000cc
Blood volume gradually returns to normal by _____ post partum
6-9 weeks
Why do pregnant women have physiologic anemia?
Intravascular fluid volume: increased 35%
….relative anemia of pregnancy due to increase of 55% in plasma volume and the erythrocyte volume increases 30%
Most common cause of PPH is ____.
uterine atony
PPH occurs in 1-5% of all deliveries
Late in pregnancy uterine artery blood flow is _____.
500-700cc/min and approx 15% of cardiac output
New/updated definition of PPH
Cumulative blood loss greater than or =1000cc
OR
Bleeding associated with signs/symptoms of hypovolemia within 24hrs of birth process
Uterine atony (first line med and second line med)
FIRST LINE = Oxytocin(30 units in 500cc LR)-lowdose/infusion
SECOND LINE = Methylergonovine .2mg IM –Ergot Alkaloid
contraindicated with hypertension or preeclampsia
Hemabate = ____. Used for?
(prostaglandin F2-alpha) 250mcg IM or endometrially for uterine atony
Misoprostol(Cytotec) = ___. used for?
prostaglandin PGE1analogue—off label rectally
used for uterine atony
could also be used sublingually
Oxytocin Hormone use
Used to induce or augment labor process
FIRST LINE drug for Uterine Tone and minimizing blood loss after delivery
FDA alerts for oxytocin
FDA high alert black box during labor for “medical indications”
SE: hypotension, tachy, flushing, emesis,
myocardial ischemia
High alert medication (InstSafeMedPractice)
Oxytocin Rule of 3s
Low dose RULE OF 3s for CESAREAN SECTION by Lawrence Tsen
3 units IV loading dose over 30 seconds/ assess at 3 minute intervals….. Give 3 IU units rescue dose…. Then 3 total doses of oxytocin initial plus 2 rescue
30IU/L at 100cc/hr
Initial 3 units is for effective Uterine contractions for laboring and nonlaboring women….
Study of Elective c/s delivery cases
(rule of 3s vs continuous “wide open” infusion)
TXA for PPH
Tranexamic acid –give within 3 hours
Lysine analogue
Prevents fibrinolysis
Competitively blocks plasminogen and plasmin
TXA dosing for PPH
TXA half life is 2-3 hours with normal renal fxn
1 gram in 100cc over 10min
1 gram in 250cc over 8hr infusion
Fibrinogen importance in pregnancy
Low is MOST predictive variable for EARLY Hemorrhage
Goal is greater than 200mg/dl
GIVE EARLY!!!!
What are the determinants of placental transfer?
Principally by DIFFUSION from maternal to fetal circulation
Concentration gradients
Maternal protein binding
Molecular weight
Lipid solubility
Degree of ionization
What are the qualities of a drug that passes RAPIDLY to the placenta?
Low protein binding
<500 molec weight
High lipid solubility
Minimal ionization
What are the qualities of a drug that passes SLOWLY to the placenta?
High protein binding
>1000 molec weight
Low lipid solubility
Maximal ionization
Benzodiazepines and the placenta
Benzodiazepines readily cross placenta/ May affect beat to beat variability
Opioids and the placenta
Opioids rapidly cross-Narcan available for neonatal respiratory depression
Ketamine and the placenta
Ketamine readily crosses, but in low doses does not cause neonatal depression
Which drugs do NOT cross the placenta?
All Neuromuscular blocking agents
Glycopyrrolate
Insulin
Heparin
Weight gain with pregnancy
Uterus 1kg
Fetus and placenta 4kg
Blood volume/fluid 4kg
Additional Fat 3kg
(Normal weight pt with BMI 18.5-24.9) is recommended total weight gain of 25-35lb
Overweight definition
Overweight
BMI 25-29.9 kg/m2
6.8-11.3 kg
(15-25 pounds)
___ pregnant women are obese – and BMI rates
Half of pregnant women are overweight or obese
C/S rates:
BMI 29 or less= 20%
BMI 35-39= 47%
Obesity and risks
Obesity-INCREASED RISK OF COMPLICATIONS
Gest DM
HTN/PEC
Fetal Macrosomia
Premature labor
Stillborn/anomalies
Infection w C/S- 2 abx
Off spring of obese mothers are at increased risk of childhood and adult obesity
Obesity related insulin resistance and inflammatory pathways linked to development of PEC
Obesity labor times
Labor duration nulliparas increased .3 hours for each 10kg increment in maternal weight
Failed induction rate twice as likely
C/Section rate BMI greater than 60kg/m2— 69%
Obese women and C/S -ABX and closure of subQ layer (reduce wound disruption)
Obesity & maternal morbidity and mortality
Normal BMI 143/10,000 women; Class 3 obesity (BMI 40 or higher…) 203/10,000 women
Hemorrhage require transfusion, serious cardiac respiratory hematologic, thrombus, embolism, sepsis shock, hepatic renal failure, uterine rupture
Cardiac changes with pregnancy - HR and SVR
Heart rate only increased 15%
LVH
SVR decreased 20% at term
Cardiac Output
Cardiac output increased 40% above non pregnant levels mostly due to 30% increase in stroke volume
Greatest increase in CO?
Immediately after delivery of placenta
Cardiac output increases 60%-80% above pre-labor values
CO returns to non pregnant value 2 weeks postpartum
CO increased mostly due to INCREASE in stroke volume… uterine contraction 300-500cc
Peripheral Circulation - SVR
Normally no change in Systolic BP
SVR is decreased by 20%
Supine Hypotensive Syndrome
Watch for supine hypotension syndrome in about 10% of patients at term…ie decreased venous return due to compression of the IVC by gravid uterus
Use left uterine displacement(LUD)!!!!
Ideal vasopressor??
ASA practice guidelines for OB anesthesia….both ephedrine and phenylephrine are acceptable agents for treating hypotension during neuraxial anesthesia.
Respiratory Changes - MV
Minute ventilation increased 50% d/t progesterone (also relaxes bronchial smooth muscle)
Respiratory Changes - TV
TV increased 40%
Respiratory Changes - RR
Resp rate increased 10%
Respiratory Changes - ERV
ERV decreased 20%
Respiratory Changes - RV
Residual volume decreased 20%
Respiratory Changes - FRC
FRC decreased 20%
Respiratory Changes - Thoracic cage
Thoracic cage increased diameter
Further Resp - TLC
Minimal/No change in VC or TLC
Further Resp - MAC requirement
Changes in anesthetic depth with GA is faster in pregnancy (decreased MAC)
Further Resp - O2 consumption
Increased oxygen consumption by 20%
Oxyhemoglobin Dissociation Curve
Left shift of oxyhemoglobin dissociation curve (fetal hemoglobin)
Respiratory alkalosis….Increased affinity for fetal hemoglobin/holds onto oxygen shift left for fetal hemoglobin diss curve….
Right shift of oxyhemoglobin dissociation curve (maternal term hemoglobin)
Maternal P50 increases from 26 to 30mmhg at term(maternal O2 diss curve shifts to RIGHT to offload Oxygen to fetus….)
Progesterone
- Increases minute ventilation
- Bronchial smooth muscle relaxed
- Hyperventilation in active labor worsens respiratory alkalosis
- Maternal P50 shift from 26-30mmHg at term so shift to right to “offload oxygen to fetus”
Resp Summary
Tidal volume increased
Slight increase in respiratory rate
FRC decreased 20%
Increased minute ventilation at term
Minute ventilation increases 100%-200% with 1st / 2nd stages of labor
FRC normal 2 weeks post partum
Airway Changes
- Capillary engorgement
- Mucosa is very friable
- Increased risk of bleeding
- Smaller size cuffed ETT (size 6-7)
- Preoxygenate!!!!!!!!!!! Increased oxygen consumption + Decreased FRC
- Engorgement of mucosa even greater in Preeclampsia (PEC)!!!
- Mallampati worsens after labor
Airway pearls - intubation and ACLS
Incidence of failed intubation = 8-10X higher parturient than the NON pregnant patient
“O2-prop-sux-tube”
FIRST THINK RSI
For ACLS cardiac arrest: intubation attempts per experienced laryngoscopist. Bleeding and airway edema.
No more than 2 attempts at either DL or videolaryngoscopy before insertion of a supraglottic airway
Supraglottic airway is preferred rescue strategy after failed intubation difficult airway algorithm-cricothyroidotomy
Risk Factors c/s GA
- Increased BMI
- Mallampati score III or IV
- Small hyoid to mentum distance
- Limited jaw protrusion
- Limited mouth opening
- Cervical spine limitations
SCR Project
(SCORE)
30 institutions USA. 1K-10Kdeliveries per institution (2004-2009)
257,000 parturients; 5,000 GA with NO aspiration
1 in 533 general anesthetics…resulted in Failed INTUBATION
2014: 31.3% of deliveries were via c/section
94.4% neuraxial anesthetics for c/s
5.6% general anesthetics for c/s
Failed neuraxial anesthetics for cesarean delivery of 1.7%
SCORE project: High Neuraxial block-risk factors
This is the most common serious
**“anesthesia related” complication*
Obesity
Spinal after failed epidural anesthetic
58 out of 85 anesthetic related complications gives 1 in 4,336 incidence
___ was the mode of delivery of __% with cardiac arrest?
Cesarean section was the mode of delivery of 88% of those who had cardiac arrest
32.6% of those with cardiac arrest survived …12 of 14 who survived full recovery.
GI Effects from Progesterone
Decreased LES tone
(lower esophageal sphincter tone)
GI effects from Estrogen
Decreases LES tone
Prolonged gastric emptying?
WOMEN IN LABOR –> RSI
GI Changes
Displaced pylorus upward and backward lower esophageal sphincter tone
Onset of uterine contractions gastric emptying is “SLOWED IN LABOR”
ALWAYS TREAT AS FULL STOMACH
GI Meds with labor
- Metoclopramide: context of C/S decreases incidence of Nausea AND Vomiting
- Sodium citrate/ nonparticulate
- H2 receptor antagonist: Pepcid does not affect ph of gastric fluid already in the stomach
ASA Guidelines - GI
Clear liquids by laboring patients without additional risk factors is acceptable
Risk factors: morbid obesity, diabetes, known difficult airway etc.
(Gastric emptying studies found emptying is not delayed with pregnancy) /risk factors
Think ph meds for aspiration prophylaxis
NPO Status
All laboring patients considered full stomach…planned RSI in emergent C/S
For elective C/S want NPO solids for 6hrs and clear liquids for 2 hours
ALL AT RISK for aspiration
Liver changes
Overall hepatic function and blood flow is unchanged
**Mild decrease in serum albumin **due to increase in plasma volume
Watch for HELLP syndrome
Hypercoagulable State - Factors
Fibrinogen (Factor I), Factor VII, VIII, IX, X and XII are increased at term relative to nonpregnant state
[1, 7, 9, 10, and 12 cause I suck with roman numerals]
Protein S
Decreased levels of Protein S
Hypercoagulable State changes purpose & thromboembolism risk
Physiologic changes to minimize intraoperative blood loss
6 fold increase risk of thromboembolism pregnancy and postpartum period –> Venodyne boots for C/S
Renal - progesterone
Progesterone leads to dilation of renal calyx, pelvis
Renal blood flow
Renal blood flow and GFR are increased 50% by 4th month of pregnancy
BUN & Creatinine
Decreased BUN and Creatinine
(.6-.8mg/dL normal for term parturient)
Cortisol
increased
Pain
increased pain threshold
Glycosuria
not necessarily abnormal
Insulin resistance?
Relative
UTI’s?
Impaired tubular reabsorption of glucose=more UTIs
Plasma Cholinesterase
Plasma cholinesterase activity is decreased by 25%-30% at term (not much clinical significance)normal by 6 wks post partum
Stages of Labor
First stage-onset of regular contractions
Second stage-begins with complete cervical dilation(10cm)
Third Stage- from delivery of baby to placenta is expelled
Pain with Labor - Visceral
Visceral is caused by uterine contactions and dilation of the cervix= FIRST STAGE
Afferent viscera first stage impulses from uterus and cervix…sympathetic n.s. T10 –L1
Pain with Labor - Somatic
Somatic pain-stretching of the vagina and perineum as fetus descends=SECOND STAGE
Late first stage and second stage of labor somatic pain receptors via pudendal nerve S2-S4
Pain review
1st stage T10-L1
2nd stage S2-S4
Labor epidurals do not prolong 2nd stage of labor when inserted at appropriate time
ASA Guidelines for L&D
Basic airway equipment =immed
FOS/Code cart=easily accessible
Cardiac arrest manual LUD=C/S within 5 minutes/PMCD
GA vs. Regional
Difficult airway algorithm-airway eval!!!
LMA use- think rescue only
Fewer GA/ trend for more regionals
20% Intralipid fat emulsion/LA Toxicity
ASRA guidelines for anticoagulated pts
Infection prevention
mainly safer because more expertise with use of AIRWAY DEVICES
Heparin recs & neuraxial
indivdual heparin dose of SQ Heparin 7500-10000 U BID or a daily dose of <= 20,000 U
We suggest neuraxial block occur 12 hours after SC Heparin administration and assessment of coag status-new recommendation for higher dose UGH thromboprophylaxis in the pregnant patient…
ABSOLUTE Contraindications to Regional
Patient refusal
Infection at site of injection
Clinical bleeding
Ongoing anticoagulation
Severe uncorrected hypovolemia
Severe aortic/mitral stenosis
Increased ICP
Relative Contraindications
Hypovolemia
Thrombocytopenia
Hemorrhage
Fetal status
Severe spinal deformity
Preexisting neurological deficit
Indications for C/S
- 35% Prior C/S
- 30% CPD/Dystocia
- 12% Breech
- 9% Non reassuring fetal tracing
- 14% other:
- Placenta Previa, Suspected Accreta
-HIV mother, active genital herpes
-previous classical incision
-previous uterine surgery
-macrosomia, twins, PEC with SEVERE sxns ( etc/eclampsia)
VEAL CHOP
Non-Reassuring Fetal Status
Persistent LATE decelerations
Uteroplacental insufficiency
Category III tracings are predictive of abnormal fetal acid base status.
* Absent baseline fetal heart rate variability AND any one of the following:
* Recurrent Late Decelerations
* Recurrent Variable Decelerations
* Bradycardia or sinusoidal pattern
Pathophys of Preeclampsia
Vascular dysfunction of placenta
Abnormal prostaglandin metabolism
Thromboxane A2-potent vasoconstrictor
Platelet aggregation
Inflammatory evidence- increased cytokine levels
Risk factor PEC in past pregnancy
Definitive goal is “delivery of placenta”!
PEC symptoms(ACOG laymen)
Headache
SOB
Eye sight changes-spots / blurry vision
Pain upper abdomen or shoulder
Edema face and/or hands
N/V 2nd half of pregnancy
Sudden weight gain
(higher risk long term –health risk- heart attack/ stroke/kidney dz/htn)
(Old term PIH)–Preeclampsia
- Age <20 or >35 (extremes of age)
- Nulliparity as well as Twins/triplets
- Family hx of preeclampsia
- sister/mother - genetic risk
- paternal antigen father fetus - if male has previously fathered a preeclampic pregnancy
- previous pregnancy with preeclampsia
- Incidence 6-8% of all pregnancies
- Type I or Type 2 DM, Obesity, lupus, IVF
- Chronic HTN renal dz or both
(ACOG 2013)
PEC prevention
- Low dose aspirin (controversial 81-150mg/day)
- Greatest benefit to women at moderate or high risk
- Low dose ASA reduces frequency of PEC as well as adverse outcome
- Preterm birth/ growth restriction
- Decreases thromboxane synthesis
- Modulates inflammation
HTN with pregnancy - chronic
BP >140/90 on two separate measurements
>4 hours apart
Gest age <20 wks
Gestational HTN
Same criteria for BP
Gest age>20wks
WITHOUT proteinuria…
And resolves by 12 wk PP
Preeclampsia WITHOUT severe features
BP>140/90 on two separate measurements
>4 hours apart
Gestational age >20 weeks
AND…..
PROTEINURIA
Greater than or equal to 300mg protein in 24 hour urine collection
Or P:C Protein to creatinine ratio greater than or equal to 0.3mg/dl
Preeclampsia WITH SEVERE features
- BP>160/110 on two separate measurements at least 4 hours apart/Gestational age >20wks
- Proteinuria NOT essential
- ANY END ORGAN DYSFUNCTION—-YES!!
- Thrombocytopenia (<100k)
- renal insufficiency (serum CR>1.1mg/dl)
- LFT 2x normal
- pulmonary edema
- new H/A or visual sxns
- RUQ or epigastric pain sign of liver involvement
HELLP syndrome
Ranges from mild condition to severe multisystem organ failure
Hemolysis (abnormal blood smear)
Increased Liver enzymes AST>70U/L and LDH>600U/L
Platelet <100,000mm3
Clinical application: What is platelet count before regional?
Key points HELLP
20% of patients with preeclampsia with severe features will develop HELLP
DELIVER ASAP
Watch trend of platelets (?epid removal) - don’t remove until rechecking PLT count
Platelets usually return to normal 72hr post delivery
Preeclampsia goals
Control HTN- 1st line labetalol/hydralazine nifedipine(oral)
Prevention of seizures -Magnesium Sulfate
Eclampsia = seizure
Delivery of fetus
Blunt hemodynamic response intubation
Magnesium Sulfate
Agent of choice SZ control pre-eclamptic(PEC)
Raises seizure threshold
Also used for preterm labor
Hypotension
Maintain infusion during C/S +24hr after delivery
Potentiates action of both nondepolarizers and depolarizing muscle relaxants
careful reversal
Magnesium Sulfate for PEC
Initial loading dose is 4 Gm MgSO4 IV over 10 minutes then maintenance infusion of 1-2 Gm/hr
(Some load dose with 6 Gm MgSO4)
Want serum range 4-6 meq/L (SSH)
Toxicity 10cc of 10% calcium gluconate
Narrow therapeutic index….5-10meq/L with EKG changes prolonged PR widened QRS…. 10 meq/L decreased deep tendon reflexes….15 meq/l respiratory arrest
Magnesium Sulfate - Toxicity
think therapeutic range Magnesium 4-6 meq/L ( Apex Magnesium range 2.1-2.9 mmol/L)
SE: feel weak/blurred vision/nausea/ hot/diminished deep tendon reflexes/////////
Avoid 6-10 meq/L EKG changes = prolonged PR/wide QRS, HYPOTENSION
10 meq/L LOSS OF deep “TENDON” reflexes
15 meq/l range is respiratory arrest… cardiac arrest
Magnesium affects uterine tone so higher risk of PPH
PEC-DELAYED presentation
SEE Handout
Triage in ER -less than 6 weeks post partum
Stabilize/ OB consult/Labs fibrinogen liver fxn type and screen / strict I and O
Initial IV Mag sulfate load dose or IM if no IV
AntiHTN meds: Labetalol IV or PO if no access
Hydralazine IV
Immediate release oral nifedipine
C/S
Scheduled
Urgent within 30 minutes
STAT
Repeat Airway evaluation must be performed prior to GA
Dosing of Regional and Pregnant Patient
Engorgement of epidural veins as intraabdominal pressure increases
Reduces volume of CSF in subarachnoid space
Facilitates spread of local anesthetic
Decrease dose requirements of local anesthetics for epidural/spinal by 30-50%
Distance threaded for Epidurals
5cm…
Remember platelet trend prior to removing epidural in suspected low platelet patient scenario….??? Think do you want to repeat platelet count prior to removal?
OB Epidural hematoma epidural abcess very RARE- 1:200,000- 1:250,000(SOAP 2018)… Symptoms hematoma rapidly preogressive neurologic deficits muscle weakness back pain sensory deficit and urinary retention Risk factors hematoma are hard to tell but defects of coagulation and multiple attempts at placement/ Also think STAT MRI AND NEUROSURGEON CONSULT
Labor Epidurals
.25 % Bupivacaine or .125% Bupivacaine
More motor block with Xylocaine 1.5%
PCEA with 1mg/cc of Bupiv+2.5mcg/cc of Fentanyl at 8-10cc/hr with 6cc bolus/6min lockout/60cc 4 hour limit
6/6/60
ALWAYS aspirate before injecting Bolus
“AMIDE” Local Anesthetics
Awareness of platelet trend removal cath?
Epidural for C/S
Epidurals for C/SOxygen /Monitors/ LUD
T4 level
15-25cc of 2%Xylo with Epi 1:200k (SSH)
May add sodium bicarbonate 4.2% for quicker onset (2cc to 20cc)
Increase in time of onset vs spinal
Rarely 3% Chloroprocaine…faster onset….ester….short DOA-think 45 min redose
Epidural during C/S
Oxygen/ Monitors/ LUD
Pressors often used: ephedrine / phenylephrine
Timeout/ Antibiotics
AFTER CORD CLAMPING --> oxytocin gtt (30u in 500cc)
2 mg EPIDURAL Duramorph(PF)
Awareness of platelet trend removal cath?
Spinal Anesthesia for C/S
Elective C/S
Repeat C/S
Approx 1.4-1.6 cc of .75% Bupivacaine with Dextrose (may adjust for patient’s height or previous record available)
.15mg Duramorph(PF) +10mcg Fentanyl
Consider Epinephrine in spinal dosing
Neo 80mcg/cc or Ephedrine 5-10mg doses incrementally…Some use IM Ephedrine 25mg …..Epi if Tubal ligation/hysterectomy possible. Fentanyl increases intensity and duration of block
Spinal Level
T4 level
Fast onset
Hypotension
Cardioaccelerator
Pain relief Duramorph
Denser block than epidural for c/s
SPINAL Opioids = post op resp - FENTANYL
Lipophilic
Quick onset
Improves sensory blockade
10mcg for spinal
SPINAL Opioids = post op resp - MORPHINE PF
Hydrophilic
Postop pain relief up to 12-24 hours
.15mg for spinal
Spinal for C/S during
Oxygen/Monitors/LUD
PRELOAD and Pressors often used:
-Ephedrine/Phenylephrine
Time out/Antibiotics
After cord clamping oxytocin(30u in 500cc)
Time runs out on spinal….
Options: Narcotic IV, Ketamine
Convert to GA
Consider combined spinal/epidural from the beginning!!!!
OB: RSI FOR GA
metoclopramide/Sodium Bicitrate/H2 Blocker?
4-5 breaths of 100% Oxygen/LUD/EKG SAT BP monitors
TIME OUT/Antibiotics/ Drapes up…surgeon+equipment
RSI – “prop-sux-tube”/Cricoid Pressure just before onset of LOC
GLIDESCOPE vs direct laryngoscopy—think!
Propofol/ Ketamine + Succinylcholine + ETT -6.5 smaller
GA in progress C/S
Non depol?
Inhal at half MAC
50%O2 + 50% N2O
After delayed cord clamp: Oxytocin gtt
70% N20 decrease Inhalation
Reverse neuromuscular blockade?/narcotic
Be aware with magnesium and reversal!!
OGT/ Extubate awake
Review of anesthesia related maternal deaths over 18 yr period showed airway factors occurred during emergence and recovery and not during induction of general anesthesia. NGT “bloody mess” use OGT
Muscle Relaxation
Inhalation agent
Succinylcholine may last slightly longer
Sensitivity to Non depolarizers with patient on Magnesium Sulfate
Summary Pharmacology
Uterine atony medications - see handout
TXA-lysine analogue-prevents fibrinolysis
RSI- Think “Prop, Sux, Tube”
Suggamadex- binds to and encapsulates progesterone-Early pregnancy-advise AGAINST
Suggamadex-At term-Avoid or use with caution as inform effects on lactation unknown- see document SOAP website 4/22/19
Magnesium is for SEIZURE prevention
Summary-General Anesthesia
- Combination Decreased FRC and Increased Minute Ventilation –> accelerates uptake
- MAC decreased 40% for inhalation anesthetics at term
- PREOXYGENATE!
- RAPID DESATURATION!
- RSI with Cricoid pressure(smaller ETT)
- OGT
- ?muscle relaxation
Post Partum Depression and more
Individualize care- speak up!10-15% of adult mothers have depressive symptoms lasting more than 6 months…
Suicide hotline is 988
HOMICIDE:* HOMICIDE is leading cause of death during pregnancy* and 42 days exceeding pregnancy
3.62 homicides per 100,000 live births among females pregnant or one yr post partum
16 times higher than nonpregnant nonpostpartum females.
Nonobstetric surgery during pregnancy
.5-2% of all pregnancies
Think care plans- how would you manage?
Most common types…
What about elective surgery? When?
Which trimester is best for non-elective surgery that cannot be postponed?
What is normal FHR? Variability?
>23 wks monitor FHR for end organ perfusion
