OB Flashcards
For OB patients, you want to make sure to have this type of cart
Difficult Airway
When is there the greatest cardiac demand on parturients?
During and right after delivery.
When are parturients at greatest risk for myocardial ischemia?
During and right after delivery, because this is the period of greatest cardiac demand
A parturient is considered a full stomach after ____ weeks
12
Why are pregnant women at risk for gallstones?
Everything in the GI tract slows down, causing stasis.
A fetus is considered acidotic if pH is
7.2
Fetal bradycardia is considered
Normal amount of variability for a fetal HR
5-25bpm
Normal fetal HR
110-160
This can cause fetal bradycardia
Maternal hypotension, maternal hypoxemia, uterine contractions/hyperstimulation, vagal head compression, umbilical cord compression.
Treat with fluids, positioning, and oxygen, stop oxytocin.
CO returns to normal ___ weeks post-partum
4 weeks
HR will increase by ____, CO increases by ____, and SV increases by _____
HR 23-30%
CO by 30-50%
SV by 20-50%
BP changes
SVR decreases by 20%, but SBP is unchanged. This is probably due to the increase in CO. MAP however, decreases slightly.
What can cause hypotension in parturients?
Supine positioning
Induction agents
Sympathetic blockade from regional blocks
Treatment of maternal hypotension
Positioning, fluids, O2, TED stockings, Ephedrine & Phenylephrine
Compression of IVC vs. aorta
IVC compression causes a decrease in venous return, CO, and thus causes hypotension.
Aortic compression is usually not associated with s/s, but does decrease uteroplacental perfusion
Plasma volume increases by __%, but RBC volume only increases by ___
50%
30%
Coagulation in parturients
Clotting factors increase (in preparation of delivery). Plts remain the same or decrease slightly.
Plasma cholinesterases in parturients (increase/decrease)
decrease.
Will have prolonged duration of sux!
EBL for vaginal delivery
500cc
EBL for c-section
800 - 1000 cc
1500 cc for hysterectomy
Regional anesthesia is not advised if plt counts are below
70,000
When should you suspect a PE?
parturients are at risk for PE because their coagulation factors have increased. PE should be suspected if mother has SOB, chest pain, coughing up blood, arrhythmias, pain or tenderness in legs.
We want mothers to ambulate early and wear compression stocking!!
Respiratory changes in parturients
Decrease in FRC (20%)
Small airways close faster
Increased WOB
O2 demand increases by 30% (increase in TV by 50%, RR also increases)
The dissociation curve will shift to the
right
Effects of progesterone on respirations
Tells resp center to increase respirations
Sensitizes the resp center to CO2 (increases MV to drive maternal PaCO2 to 30-32, causing a compensated respiratory alkalosis with excretion of bicarb)
Chest muscle relaxation, allowing the chest wall to expand more easily
ABG of pregnant women
Remember that they have increased sensitivity to CO2 d/t progesterone, so they have an increased MV. This results in a compensated respiratory alkalosis, normal pH, low pCO2, and low bicarb
Why is it important for parturients to have oxygen?
Increased oxygen consumption, decreased FRC, and decreased CO when supine
Why is hypoventilation in parturients so bad?
It decreases O2 availability to fetus, also, mothers can quickly develop acidosis, causing BVs to constrict, decreasing flow uteroplacental flow
Will IAs have a faster or slower effect on parturients?
Faster
d/t increase in MV
Choice of ETT size in parturients
6.0-7.0
Generall err on the smaller side, because they may have edematous airways
Clinical implication of full stomach past 12 weeks rule
Bicitra given to all laboring women
Reglan
H2 Antagonists (Ranitidine, Famotidine)
GI changes
Stomach displaced upward & 45° to the right & displaces the intra-abdominal segment of the esophagus into the thorax → ↓ tone of the lower esophagus → ↑ incidence of reflux
Mechanical obstruction to outflow through pylorus → ↑ gastric volume
↑ gastric acidity (placental derived gastrin mediated)
Esophageal peristalsis & intestinal transit slowed → ↑ gastric volume
Labor pains and opioids delay gastric emptying and promote emesis
CNS changes
Increase in endorphine (higher pain threshold)
Increased sensitivity to IAs, LAs, and opioids (decreased anesthetic requirements)
MAC requirements decrease by ___% in parturients
40%
Renal Changes
Increase in RBF and GFR d/t increased CO
Increased creatinine clearance – because of this, lower serum BUN/Cr & uric acid values
increased excretion of glucose and bicarb (compensation for resp alkalosis)
Formula for Uterine Blood Flow
(Uterine arterial BP - Uterine Venous BP) / (Uterine vascular resistance)
Normal uterine blood flow at term
500-700cc/min
Why is maternal hypotension such a big deal?
The uterine vascular bed lacks autoregulation!!!! Maternal UBF is dependent on BP and CO
Factors that increase uterine vascular resistance, and thus decrease UBF
Oxytocin, contractions, ketamine, abruptio placentae, and severe HTN)
Drug transfer across the placenta depends on
MW Size Lipid Solubility Maternal drug concentration Maternal and fetal pH (more non-onized means more transfer) Low protein binding
What is the single best non-invasive indicator of fetal well-being??? **
Fetal HR variability
Should be between 5-25bpm
Signals an intact CNS and normal cardiac function
Causes of fetal tachycardia
FHR > 160
Chronic fetal distress
Fetal hypoxia
Maternal Fever
Hyperthyroidism
Parasympatholytic medications (atropine, etc)
Sympathomimetic medications (epi, ephedrine, terbutaline)
Fetal bradycardia is a FHR
110
Causes of loss of variability
drug effect - general anesthetics, opioids, hypnotics, ethanol, mag sulfate
fetal sleep
fetal distress - CNS depression (hypoxia, asphyxia, neuro abnormalities)
Early decels
Develop with uterine contraction (it mirrors them).
Head compression from contraction causing increased vagal tone.
Shape uniform, HR changes mild
These decels are transient and well tolerated by the fetus.
If treatment needed - Atropine cause it’s a vegal response (giving supplemental O2 will not fix anything)
Late decels
Non-reassuring pattern - represent uteroplacental insufficiency + fetal compromise / fetal hypoxia
r/t decreased uterine blood flow, hypotension, uterine hyperstimulation
Begin AFTER onset of uterine contraction (20 sec or more later).
May be caused by CNS or myocardial ischemia or fetal hypoxia.
This is an ominous sign!!
Treatment: Materal OXYGEN, Check Mom’s BP- Ephedrine if necessary (improves blood flow to baby); LUD or position change; IV fluids; Suggest “stop Pitocin” to decrease uterine tone; C-SECTION, C-SECTION, C-SECTION STAT is often the definitive treatment.
Variable Decels
Most common pattern observed in the intrapartum period. Represent intermittent compression of the umbilical cord (sometimes head compression) - Baroreflex-mediated response to compression of umbilical cord
Variable (non-uniform) in shape and timing/onset, short in duration, and nadir (lowest point) occurs within 30 seconds of onset.
If the compressions are frequent or prolonged, it could result in fetal asphyxia (if consistent/sustained FHR 60 sec. and/or where subsequent loss of variability occurs)
Treatment: position change
Intrauterine resuscitation
treatment of fetal distress
1) Supplemental oxygen
2) LUD or knee-to-chest positioning
3) Rapid fluid infusion
4) Check maternal vital signs, and treat hypotension with pressors
5) Stop oxytocin if it was being given, and begin tocolysis with terbutaline or NTG
6) Assess level of blockade for spinal/epidural (stop?)
7) Amnioinfusion (inserting fluid in the uterine cavity to decrease cord compression)
8) C-section
Opioids in the laboring woman
They are commonly given, although data suggests that they provide limited analgesia.
1) Meperidine (Demerol) 25-50mg is traditionally the most common. However, the metabolite normeperidine can linger in the fetal circulation, and cause depression.
Opioids also have unwanted SE, such as N/V, resp depression, sedation, orthostatic hypotension, and neonatal depression.
2) PCAs of fentanyl or remifentanil may be used.
3) Agonist/antagonists such as butorphenol and nalbuphine are also used. –> Benefit of decreased N/V and ceiling effect of respiratory depression. Nalbuphine (Nubain) has less dysphoria than butorphenol.
Gases for laboring pain
1) Entonox - 50/50 mix of nitrous and O2
2) Sevoflurane
Stages of Labor and Blocks Needed
1st
- Beginning of painful contractions to full dilation
- Longest Stage
- Mostly visceral pain
- T10-L1 innervation
2nd
- Complete dilation to delivery
- Most painful stage (somatic pain)
- L2-S4 innervation
3rd
- From delivery of baby to delivery of placenta
Midazolam in laboring women
Low doses .5-1mg to provide anxiolysis, but make sure they remember the delivery
Epidural catheter is inserted __-__cm into epidural space for parturients
4-6cm
Normal population is 2-3cm
LA of choice for emergency c-section
Chlorprocaine (d/t highly rapid onset)
Rules for epidurals
Want to be at least 4cm dilated BP every 2 min Inserted bellow L2 (so go L3 or lower) Test dose between contractions Always aspirate before each dose Fluid load with 500cc crystalloids before induction
CSE is great option for women, but carries increased risk of
non-reassuring FHR patterns and fetal bradycardia
Treatment for PDPH
Bedrest Caffeine Hydration OTC analgesics Epidural blood patch
Most common reasons for having a c-section
Previous c-section Cephalopelvic Disproportion (CPD) Failure to progress Malpresentation Prematurity Non-reassuring fetal status
This is the preferred muscle relaxant for c-section under general anesthesia
Sux (guessing d/t short duration) and need for RSI
If can’t use sux, rocuronium is a suitable alternative
Induction agent of choice if the mother is having a hypotensive crisis
Ketamine 1-1.5mg/kg
Time between incision of the uterus and delivery of the fetus MUST be less than ___ minutes
3
Optimal dose of bupivacaine for spinals for C/S
12mg
Provides block for 1.5-2 hours
Need this levels spinal block for C/S
T4
How to prevent hypotension with spinal blockade
2L crystalloid
LUD
Pressors
What is the first line pressor for parturients?
Ephedrine
Top causes of maternal death related to anesthesia
#1 Airway problems #2 LA toxicity
PIH definition
Pregnancy Induced HTN
BP > 140-90 or BP > 30 points SBP from baseline or >15 points DBP from baseline
Severe HTN in 160/110
PIH can cause
Cerebral hemorrhage, abruptio placentae, liver and renal failure, DIC
Risk factors for PIH
Primiparity Multiple gestation Chronic HTN African Americans Chronic Renal Disease Obesity Diabetes Family history of pre-eclampsia
These should all make logical sense
What is preeclampsia?
A hypertensive disorder. New onset of HTN that develops after 20 weeks gestation, along with proteinuria.
HTN without proteinuria is just PIH.
Symptoms associated with preeclampsia, and other disorders it can lead to
Associated with vasoconstriction (causes HTN), edema (proteinuria), hypovolemia, coagulation abnormalities, and poor organ perfusion.
Can lead to cerebral bleeds, pulmonary edema, hepatic rupture, and HELLP syndrome. May experience epigastric pain if there is liver involvement.
Mild vs. severe preeclampsia
Mild
- BP > 140-90 or BP > 30 points SBP from baseline or >15 points DBP from baseline
- Proteinuria > 500mg/day
SEVERE
- BP > 160/110
- Proteinuria > 5g/day
- CNS changes, blurred vision
- Hepatic involvement/epigastric pain
- Pulmonary edema
What is eclampsia?
Defined as preeclampsia with seizures.
This is a life threatening emergency
Treatment of eclampsia
O2 (A,B,C’s), LUD, IV access, Magnesium Sulfate, Antihypertensives, fluid balance, coag studies
Goal of treatment of preeclampsia
1) control of HTN
2) prevention of seizures
3) delivery of fetus (definitive treatment)
Control HTN (need a-line) - labetalol, hydralazine - goal DBP
Magnesium Sulfate
Drug of choice for hyperreflexia, and precention/control of seizures related to preeclampsia and eclampsia
Causes relaxation of vascular, bronchial, and uterine smooth muscle**
decreases cerebral irritability &prevents/treats seizures
Vasodilator - hypotension
Mild sedative
Potentiates NDMRs
Crosses the placenta (causes neonatal hypotonia and resp depression)
Dose of Mag Sulfate therapy
Bolus 4g over 10 min
Then maintenance of 1g/hr
Mag Sulfate effects can be reversed with
Calcium
Calcium Gluconate 1g
or Calcium Chloride 300mg
Paralytic of choice for those on Mag Sulfate therapy
Sux 1mg/kg
NEVER give defasciculating dose prior
If giving NDMRs, recognize that mag will potentiate these, and give only 1/3 to 1/2 of the normal maintenance dose
Pressors for those on mag therapy
Decreases the response of alpha agonists, so neo and ephedrine won’t work great. But ephedrine is preferred to neo.
What is HELLP syndrome?
Severe form of preeclampsia characterized by
Hemolytic anemia Elevated Liver enzymes and Low Platelet counts
Can be mild or be so severe that it causes multiorgan failure
S/S of HELLP syndrome
Hallmark sign is hemolytic anemia!!
Epigastric pain is the most common initial symptom (90%)
Malaise (90%)
N/V (50%)
Risks of vaginal birth after cesarean
1% change uterine rupture–> emergency for both mother and fetus
Uterine infections
May need blood transfusion
Risk of an emergency c-section
How to relax the uterus
Sevoflurane
Nitroglycerin 50-100mcg
Multiple gestations is associated with
Abnormal fetal positions
PIH
Premature labor
Increased risk of potpartum hemorrhage d/t uterine atony
Higher anesthesia morbidity (more aortocaval compression, even lower FRC, high risk for spinals and epidurals)
Definition of preterm labor
Regular uterine contractions that occur between 20-37 weeks of age.
This is the leading cause of perinatal morbidity and mortality***
Fetus at high risk for resp issues and intracraniall hemorrhage (d/t soft intracranial vault)
Treatment for premature labor
Bedrest FHR monitoring Check for PROM Tocolytic agents --> CCBs (nifedipine) --> NSAIDs (indomethacin and ketorolac) --> B2 agonists (Terbutaline) --> Mag sulfate Steroids for surfactant production
Affects of NSAIDs on the fetus
Constriction of ductus arteriosus, pulmonary HTN, renal dysfunction, intraventricular hemorrhage
EBL for C/S with hysterectomy
1500cc
Treatment of postpartum hemorrhage
- Volume replacement (more concerned with fluid than necessarily giving blood)
- Blood (give type-specific but uncrossmatched if an emergency)
- Drugs
- -> Oxytocin
- -> Ergot alkaloids (methergin & ergocitrate)
- -> Prostaglandins
- Embolization of uterine/ovarian arteries
- Hysterectomy
Placenta previa is characterized by
Painless, bright red, vaginal bleeding
Anesthesia management for placenta previa
Prepare for high blood loss
- Aggressive fluids (may need central line)
- Foley
- May need a-line
- Large bore IVs
- Be ready in the OR for either regional or GA. Have both set up and ready to go!
- Do regional if stable
- If unstable, do GETA with RSI using ketamine or etomidate
Characteristics of abruptio placentae
Painful, dark, clotted, vaginal bleeding
Bleeding may be underestimated because blood may be concealed behind the placenta
Maternal mortality high (2-11%), and fetal mortality is even higher (50%).
What is placenta accreta?
Abnormally adherent placenta to the uterus
Placenta vera- adhered to the myometrium with invasion of the uterine muscle
Placenta increta- invasion into the myometrium
Placenta percreta- invasion through the myometrium, and into the surrounding structures of the uterine serosa and pelvis
First sign of uterine inversion
Hypotension! There is blood loss, but the fundus of the uterus is blocking it’s exit through the vajay. Therefore, the first thing you will see is hypotension.
Dose of NTG for uterine relaxation
1mcg/kg
Usually 50-200mcg
Amniotic Fluid Embolism
1) Acts as an embolus and get can lodged in places
2) Body recognizes it as foreign, resulting in an anaphylactic/anaphylactoid reaction
- –> Clinically looks like PE + anaphylaxis –> this is why mortality rate is so high (60-80%)
In morbidly obese patients, LA volume should be (increased/decreased)
Decreased (less space in the epidural space)
If a parturient requires non-OB surgery, this is the most vulnerable time for them to have it
3-8 weeks gestation, because there is lots of growth and development occurring.
Regional is always best option! Minimizes exposure to systemic anesthetic medications
Parturients often present for these non-OB surgeries
Cholecystectomies and appendectomies
Avoid these known teratogens especially in the first semester
N2O and benzos
– benzos linked to cleft lip/palate
FHR monitoring isn’t needed if fetus is less than ___ weeks
20 (no chance of viability even if emergency occurs)
