Obstetrics Flashcards
How does the airway change in the parturient?
Increased mallampati score
Diff intubation is 8x higher
Glottic opening is narrowed (smaller tube)
Datta handle (shorter) is useful
Tissue in nasapharynx is friable
Increased airway edema
What hormone relaxes the ligaments in the rib cage?
Relaxin
How is the lung affected in the parturient?
Decreased FRC
Increased O2 consumption ~ onset of hypoxemia is quick
Airway closure during tidal breathing.
Which hormone is a resp stimulant?
Progesterone
What is the ABG for a parturient?
pH ~ normal
PaCO2 ~ decreased (30ish)
PaO2 ~ ^ 105ish
HCO3 ~ decreased (20ish)
How does the OxyHgb dissociation curve shift?
Increase in P50 > shift to the right
***facilitates transfer of O2 to fetus
How does minute vent change in the parturient?
Increase in tidal volume
Increase in resp rate
**overall increase in minute ventilation
How do lung capacities change in the parturient?
TLC ~ decreased
VC ~ no change
FRC ~deceased
Expiratory reserve ~ decreased
Residual volume ~ decreased
Closing capacity ~ no change
How does the oxygen consumption change for the parturient?
Term: 20%
First stage of labor: 40%
Second stage of labor: 75%
How does O2 consumption change for the parturient?
Increases 20%
How does cardiac output change for the parturient?
Increased by 40%
HR ~ ^
SV ~ ^
***CO during labor is different
1st stage: 20%
2nd stage: 50%
3 stage: 80% (auto transfusion from placenta)
How does BP change for the parturient?
MAP ~ no change
SBP ~ no change
DBP ~ decreased
Increased in volume + decrease in SVR = net effect
How does vascular resistance change in the parturient?
Decreased SVR and PVR
***progesterone increases nitric oxide
(They have a decreased response to angiotensin and NE!!)
How do filling pressure change for the parturient?
No change due to compensatory vascular changes
How does the cardiac axis change in the parturient?
Left deviation
At what point should we displace the parturient mother’s right torso to relieve aortocaval compression?
2nd or 3rd trimester
How does the intravascular fluid change for the parturient?
Increased by 35%
- increased plasma
- increase RBCs
**this prepares mom for hemorrhage with labor
How does the hematological system change for the parturient?
Pregnancy causes HYPER-COAGULABLE state
Clotting factors: increased (1, 7, 8, 9, 10, 12)
Decreased antithrombin
Decreased protein S
Increased fibrin breakdown
Decreased 11 and 13
What is the bottom line for the parturient and her hematological state?
Mom makes more clot, BUT she also breaks it down faster
what are the neurological changes with pregnancy?
Decreased MAC
Increased sensitivity to local anesthetics ~ decreased epidural space and increased epidural vein volume
What are the GI changes in the parturient?
Increased gastric volume
Decreased gastric pH
Decreased sphincter tone
Decreased gastric emptying (after labor begins)
How is the renal system affected in the parturient?
Increased GFR (blood volume)
Increased creatinine clearance (blood volume)
Increased glucose in urine (d/t increased GFR)
**decreased creatinine and BUN (d/t increased creatinine clearance) obvs!!
What is uterine blood flow?
700-900 mL/min
How does preganancy affect serum albumin?
Decreases
How does pregnancy affect pseudocholinesterase?
Decreases (but not meaningful for sux)
Is uterine blood flow autoregulates?
NO!! Dependent on maternal MAP, CO, and uterine vascular resistance
What % of cardiac output is uterine blood flow in the parturient?
10%
What does new research say about neo for pregnant moms?
It’s just as good as ephedrine with LESS fetal acidosis
What type of meds can easily transfer via the placenta?
Local ansthetics
IV anesthetics
Volatile anesthetics
Opioids
Benzos
Atropine
Beta-blockers
Mag
What types of meds can’t transfer the placenta?
NMB
Heparin
Insulin
Glyco
When does the first stage of labor begin/end?
Begins: cervical dilation
Ends: full cervical dilation (10 cm)
**divided into latent and active phase
When does the second stage of labor begin?
Begin: with full cervical dilation
Ends: the delivery of the newborn
**pain in the perineum begins here!
When does the third stage of labor begin/end?
Begin: delivery of the newborn
End: delivery of the placenta
What do the cervical dilation in the latent phase?
Latent phase ends when cervix is 2-3 cm dilated
What is the cervical dilation in the active phase?
Active phase occurs when cervix is 3-10 cm dilated
When is a laboring mom considered a full stomach?
Always!!!
When can a laboring mother who is healthy drink?
Moderate amount of clear liquids throughout labor
When can a laboring mother who is healthy eat food?
Up until a neuraxial block is placed
Does an epidural prolong first stage of labor?
NO!
Does an epidural increase the need for a c-section?
NO!
Where is the pain located in the first stage of labor?
T10-L1
Lower uterine segment and the cervix
Where is the pain located during the second stage of labor?
S2-S4
In addition of pain from vagina, perineum, and pelvic floor
Neuraxial techniques must be extended to cover S2-S4 range
What are appropriate regional techniques for the first stage of labor? I.e. T10-L1
Epidural
Paravertebral lumbar block
Paracervical block (high risk of fetal bradycardia)
What are appropriate anesthetic techniques for the second stage of labor? S2-S4
Neuraxial or Pudendal nerve block
What are some consequences of uncontrolled pain?
Increased maternal catecholamines > hypertension and reduced uterine blood flow
Maternal hyperventilation > alkalosis > leftward shift > decreased delivery of O2 to the fetus
What is the most common CSE approach?
“Needle through the needle”
What is the epidural volume extension technique?
Injection of saline into the epidural space immediately after the local anesthetic is administered into the subarachnoid space
*compresses subarachnoid space ~ enhances rostral spread
Does Nitrous 50/50 (50% O2) affect uterine contractility?
It doesn’t!
Which local anesthetic reduces the efficacies of epidural morphine?
2-Chloroprocaine ~ antagonizes Mu and kappa receptors
What is a pure S-enantiomer of Bupivacaine?
Levobupivacaine
Less CV toxicity (not available in US though) :(
Which local anesthetic is useful in emergency c/s when epidural is ALREADY in place?
2-Chloroprocaine
Min. Placental transfer
Why is lidocaine not popular for labor analgesia?
Very strong motor block, BUT it’s great for C/S
Which enantiomer of Bupivacaine is associated with cardio toxicity?
R-enantiomer.
0.75% contraindicated via epidural due to risk of toxicity!
What 3 things do neuraxial opioids have!
No loss of proprioception
No Sympathectomy
Do not impair mom’s ability to push
Which opioid has local anesthetic properties?
Meperidine
What are the three main ways a patient can develop a total spinal?
An epidural dose is injected into the subarachnoid space
An epidural dose is injected into the subdural space
A single shot spinal after a failed epidural block
Which accidental epidural catheter placement will neither a test dose or catheter aspiration rule out?
SubDURAL injection!
Rare but possible
With a subdural injection, how long will it take for the patient to experience symptoms?
10-25 mins
What is the tx for a high spinal?
Vasopressors
IVF
Left uterine displacement
Leg elevation
Intubation if patient is unable to protect airway!
What is a normal fetal HR?
110-160
What is a bradycardia fetal heart rate?
< 110
Maternal: Hypoxemia
Drugs that decrease uteri placental perfusion
Fetal: asphyxia, acidosis
What is a tachycardic fetal rate?
> 160
Maternal: fever, chorioamnionitis, atropine, ephedrine, and terbutaline
Fetal: hypoxemia, arrhythmias
What are early decelerations related to?
Head compression (no risk for fetal hypoxemia)
What are late decelerations associated with?
Uteroplacental insufficiency
(Maternal hypotension, hypovolemia, acidosis, preeclampsia)
*risk for fetal hypoxemia
What are variable decelerations associated with?
Umbilical cord compression
*Risk for fetal hypoxemia
What is the mnemonic VEAL CHOP
Variable decels ~ Cord compression
Early decels ~ Head compression
Accelerations ~ Ok/ give O2
Late decels ~ Placental insufficiency
In a category 3 patient (assessing for fetal heart rate), what are some findings?
***significant threat to fetal oxygenation!
Bradycardia
Absent baseline variability
Recurrent late decelerations
Recurrent variable decelerations
SINUSOIDAL pattern.
Does someone who is trained in fetal monitoring must monitor and document fetal status before and after any anesthetic procedure?
Yes
What is the leading cause of perinatal morbidity and mortality?
Premature delivery
What are the main complications (to the fetus) with a premature delivery?
Resp distress
Intraventricular hemorrhage
NEC
Hypoglycemia
Hypocalcemia
Hyperbilirubinemia
What are tocolytics used for?
To ultimately delay labor by suppressing uterine contractions (up to 24-48 hours).
**they provide a bridge that allows the corticosteroids time to work
How do beta-2 agonists affect premature labor?
Beta 2 stimulation increases intracellular cAMP ~ this turns off myosin light chain kinase > results in uterine RELAXATION
What are the side effects of Beta-2 Agonists used during premature labor?
Beta-2 agonists:
Hyperglycemia ~ baby at risk for hypo!
Fetal tachycardia
Hypokalemia
How does Magnesium affect premature labor? MOA
Calcium antagonist ~ relaxes smooth muscle by turning off myosin light-chain kinase in the vascular, airway, and uterus. Also hyperpolarizes membranes I’m excitable tissue
What is a normal mg level?
2 mg/dL
At what mg level would you have drowsiness and lethargy?
5ish
At what mg level would you have loss of deep tendon reflexes, hypotension and somnolence?
10ish mg/dL
at what mg level do you have resp depression , apnea, and cardiac arrest/block?
> 12 mg/dL
How does mg affect NMB?
Potentiates skeletal muscle weakness
What are the treatments to HYPERmagnesemia?
Support
Diuretics (excretion of mg)
IV calcium gluconate
How do calcium channel blocks affect premature delivery?
Block influx of Ca into uterine muscle > reduces Ca release from SR > relaxes muscle
What is the first-line CCB used for premature labor?
Nifedipine
What is premature delivery?
Delivery < 37 weeks or less than 259 days
What is the dose of methergine?
0.2 mg
IT SHOULD ALWAYS BE GIVEN IM
**IV admin is associated with severe HTN
What is oxytocin?
Uterotonic that is synthesized in the paraventricular nuclei of the hypothalamus.
***stored and released from posterior pituitary
What are the clinical uses of oxytocin?
Induction
Uterine hypotonia
Hemorrhage
When is oxytocin administered during a C/S?
After delivery of placenta
What are the side effects of oxytocin?
Water retention (similar to ADH), Hyponatremia, hypotension, reflex tachycardia, and coronary vasoconstriction
***rapid IV can cause cardiovascular collapse
What is methergine?
Ergot Alkaloid
Second line uterotonic!
IV administration can cause significant vasoconstriction, HTN and cerebral hemorrhage
What is Prostaglandin F2 (Hemabate or Carboprost)?
Third line uterotonic
Dose: 250 mcg IM or injected into uterus
What are the side effects of prostaglandin F2?
Hemabate!
Bronchospasm, N&V, hypotension, hypertension
In what conditions is a general anesthetic more appropriate that a regional technique for C/S?
Maternal hemorrhage
Fetal distress
Coagulopathy
Pt refusal of regional
Contraindications to regional
What are the benefits of general anesthesia?
Fast onset
Secured airway
Greater Hemodynamic stability
What are the downsides of general anesthetia for a C/S?
Difficult mask
Difficult intubation
Risk of aspiration
Potential MH
Neonatal resp and CNS depression
What is the most common cause of maternal death in a parturient undergoing C/S?
Failure to manage the airway
What is the triple prophylaxis given for parturients undergoing a C/S?
Sodium citrate
H2 receptor antagonist (ranitidine)
Gastrokinectic agent (Reglan)
What is the recommended time frame between uterine incision and delivery?
3 minutes.
Anything beyond that increases the risk of fetal acidosis
What is the best trimester for surgery in the pregnant patient?
2nd trimester
When is teratogenicity the highest?
During organogenesis (day 13-60)
At what gestation are pregnant women considered a “full stomach”?
18-20
When should the antiemetics prior to a C/S be given?
Sodium citrate ~ 30 mins
H2 antagonist ~ 1 hours
Gastric prokinetic ~ 1 hour before induction
Why should you avoid NSAIDs after the first trimester?
The potentially close the ductus arteriosus
When considering obstetric HTN disorders, what is chronic HTN?
Occurs before 20 weeks gestation and do NOT return to normal after delivery.
When considering obstetric HTN disorders, what is gestational HTN?
Occurs after 20 wks
Proteinuria does NOT occur
**Patient returns to normotensive state
When considering obstetric HTN disorders, what is preeclampsia?
HTN ( mild > 140/90 or severe > 160/110) that develops AFTER 29 weeks
+ proteinuria
(Or if the patient has any of the following:)
RUQ pain
CNS symptoms (headache)
Fetal growth restriction
Thrombocytopenia
Elevated serum liver enzymes
When does severe preeclampsia occur?
BP > 160/110
When does eclampsia occur?
When the mother with preeclampsia develops seizures
What does a healthy placenta produce in equal amounts? What does a patient with preeclampsia produce instead?
Healthy: thromboxane = prostacyclin
Preeclampsia: thromboxane > prostacyclin
What are some key complications associated with preeclampsia?
Heart failure
Pulmonary edema
Intracranial hemorrhage
Cerebral edema
DIC
Proteinuria
What is the definite treatment for preeclampsia and eclampsia?
Delivery of the fetus and placenta
with preeclampsia, when are the risks for pulmonary HTN and stroke the highest?
Postpartum period
What is HELLP syndrome?
Hemolysis
Elevated-Liver enzymes
Low- Platelet
What is the definitely treatment for HELLP syndrome?
Delivery of the fetus
What is cocaine abuse associated with?
Low platelet count
What is placenta previa?
Placenta covers the cervical os
What is placenta accrete?
Placenta attaches to the surface of the myometrium
What is placenta increta?
Placenta that invades the myometrium
What is placenta percreta?
Placenta extends beyond the uterus
What is the mnemonic for the categories of placenta previa?
“PAIN in the Pussy” in increasing severity
Previa: first ~ just covers is
Accreta ~ myometrium surface
Increta ~ invades “inside” myometrium
Percreta ~ goes beyond the “pussy”
What is associated with PAINLESS bleeding?
Placenta previa
Will probs require a c-section
What is placental abruption?
PAINFUL bleeding
Placenta has separated from the uterine wall.
***can result in maternal hemorrhage!!!
Risk factors: HTN, preeclampsia, PIH, cocaine, smoking, ETOH
Will need C/S
What is the most common cause of postpartum hemorrhage?
Uterine atony
What are the risk factors to uterine atony?
Multiparity
Multiple gestation
Polyhydramnios
Prolonged oxytocin infusion
What medications is used for the retrieval of retained placenta/placenta fragments?
IV nitroglycerin
What 3 things is DIC associated with in the parturient?
Amniotic fluid embolism
Placenta abruption
Intrauterine demise
What are the apgar score for fetal heart rate?
0 ~ none
1 ~ < 100
2 ~ > 100
What are the apgar score for resp rate?
0 ~ absent
1 ~ slow, irregular
2~ normal, crying
What are the apgar score for muscle tone?
0 ~ limp
1 ~ some flexion
2~ active motion
What are the apgar score for reflex irritability?
0 ~ absent
1 ~ grimace
2 ~ cough, sneeze, cry
What are the apgar score for color?
0 ~ pale, blue
1~ pink body, blue extremities
2~ completely pink!
What is a normal fetal resp rate?
30-60
What is a normal fetal HR?
120-160
What is a NORMAL SpO2 after delivery?
60%
***it should rise to 90% after 10 mins
What is the BEST indicator of adequate ventilation?
Resolution of bradycardia
