Obstetrics Flashcards
Risk Factors for Placental Abruption
HTN, increased maternal age, increased BMI, smoking, cocaine, external trauma
Effects of pregnancy on Respiratory function
- Capillary engorgement in mucosa (begins 1st trimester)
- Increases minute ventilation, tidal volume, O2 consumption
- PaCO2 decreases to ~30mmHg
- Increase in pH to ~7.44
- Decrease FRC by fifth month
**Inhalational induction occurs more rapidly 2/2 alveolar hyperventilation and decreased FRC
Effects of pregnancy on Cardiovascular system
- CO increases (highest in immediate post-partum period)
- Stroke Volume and Heart Rate increases
- SVR decreases
- CVP remains unchanged
- Aortocaval compression begins at 20 weeks
Effects of pregnancy on the GI system
- No alteration of gastric emptying or gastric fluid volume
- Gastric motility decreased during active labor (nrml pre-labor)
- Decreased lower esophageal sphincter tone (d/t increased progesterone level)
- Increased risk of aspiration (decreased LES tone and increased difficult intubation risk)
- Distortion of gastric anatomy 2/2 growing uterus
- Increased gastric acidity
- Increased heartburn/reflux
**Pregnant patients after 1st trimester should always be considered to have full stomach
Effects of pregnancy on Hematologic System
- Intravascular fluid volume increase
- Plasma volume increase
- RBC volume increase (less than plasma volume = physiologic anemia)
- Increased Factors 1 (fibrinogen), 7, 8, 9, 10, 12
- Increased plasminogen, fibrin, fibrinopeptide A
- Decreased Factors 11 and 13
- Unchanged Factors 2 and 5
- Unchanged platelet count
Absolute Contraindications to Neuraxial Anesthesia
- Patient refusal or inability to cooperate
- Uncorrected maternal hypovolemia or hypovolemic shock
- Infection at site of needle insertion
- Frank coagulopathy
- Recent pharmacologic anticoagulation
- Mass lesion causing increased ICP
- Providers’ lack of experience in technique
- Lack of appropriate monitoring or resuscitative equipment
Relative contraindications of Neuraxial Anesthesia
- Maternal systemic infection
- Neurologic disease
- Severe stenotic heart lesion
- Isolated blood coagulation test abnormalities
What is Preeclampsia?
Multiorgan disease characterized by HTN (SBP >140, DBP > 90) along with proteinuria (>300 mg, 1+ on urine dip stick) or end-organ dysfunction (thrombocytopenia (< 100,000), elevated LFTs, elevated Cr (>1.1), pulmonary edema, or new onset cerebral/visual disturbances) AFTER the 20th week of gestation
What is Preeclampsia with Severe Features?
- BP: SBP >160, DBP > 110
- Thrombocytopenia: < 100,000
- Serum Cr > 1.1
- Pulmonary edema
- New onset Cerebral or Visual disturbances
- Impaired liver function (Increased LFTs, severe, persistent RUQ or epigastric pain)
Complications associated with Preeclampsia
- DIC
- CHF w/ pulmonary edema
- Oligohydramnios
- Intracranial hemorrhage
- leading cause of maternal death
- Small for gestational age
- Acute kidney injury
- Rupture of liver
- Cerebrovascular accident
- Septic shock
Therapeutic range of Magnesium
Serum Levels and Signs of Magnesium toxicity
Therapeutic range: 4-6 mEq/L
Toxicity range:
- Loss of Deep Tendon Reflex: 7 mEq/L
- Prolonged PQ interval and widening QRS: 7-10 mEq/L
- Respiratory Depression: 10 mEq/L
- Cardiac arrest and Asystole: 25 mEq/L
Conditions mandating immediate delivery in Preeclamptic women (regardless of gestational age)
- Severe HTN that is unresponsive to antihypertensive meds
- HELLP syndrome
- Epigastric or RUQ pain unresponsive to analgesics
- Persistent headache or other neurologic sequelae of preeclampsia (seizures, stroke)
- New or worsening renal dysfunction (incl. severe oliguria)
- Pulmonary edema
- Evidence of deteriorating fetal status
Management of Eclampsia
- Turn patient to left side, apply jaw thrust
- Administer oxygen
- Apply pulsox and monitor
- Secure IV access
- Check BP at frequent intervals
- Monitor ECG
- Secure airway with aspiration precautions if necessary
- Administer magnesium sulfate
- Deliver baby expeditiously after maternal stabilization
Sensory level of analgesia for labor and delivery
First stage of labor: T10-L1
Second stage of labor: S2-S4
Treatment of abnormal fetal heart rate pattern w/ maternal HoTN after neuraxial placement
- Administer oxygen with face mask
- Left uterine displacement
- Administer IV fluids
- Elevation of lower extremities to facilitate venous return
- Administer phenylephrine or ephedrine
Management and Signs/Symptoms of of Total Spinal Anesthesia (High Spinal)
S/S: agitation, dyspnea, difficulty speaking
Management:
- Avoid aortocaval compression
- Administer 100% oxygen
- Provide positive pressure ventilation
- preferably via ETT
- Monitor BP, ECG recording, and fetal HR
- Support maternal circulation w/ IV fluids and vasopressors (Epic if needed)
General Anesthesia technique in Preeclamptic patient
- Aspiration prophylaxis
- oral non particulate (sodium citrate)
- H2 blocker (famotidine)
- metoclopramide
- Consider placement of arterial catheter before induction
- Prepare for difficult airway
- video laryngoscope
- Preoxygenation and denitrogenation w/ 100% oxygen through face mask
- Induction of anesthesia w/ cricoid pressure and either propofol and/or etomidate
- Succinylcholine (1.5 mg/kg)
7 Smaller ETT b/c airway edema - Continue magnesium sulfate administration intra-op and post-op
- potentiates both depolarizing and nondepolarizing NMDB
- Administer volatile anesthetic until delivery
- Consider adding nitrous oxide and reduce volatile to 0.5-0.75 MAC after delivery to reduce uterine atony and bleeding
What are the determinants of fetal oxygenation?
- Blood flow (maternal and fetal placental)
- Maternal blood oxygen capacity
- Maternal and fetal blood oxygen affinity
- Placental oxygen diffusion capacity and oxygen consumption
What are the determinants of uterine blood flow?
Ohm's law:
Uterine Blood Flow =
(uterine artery pressure -uterine venous p.)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
uterine artery resistance
-Uterine blood flow is directly related to maternal CO since uterine vessels DON’T autoregulate
What is normal FHR with beat to beat variability?
FHR 110 - 160
Beat-to-Beat variability: 6-25 beats per min
Early Decelerations
Vagal response to Head compression
Late Decelerations
Uteroplacental insufficiency
Variable Decelerations
Reflect fetal blood pressure changes d/t umbilical cord compression or changes in fetal oxygenation
Why are pregnant patients at increased risk of aspiration?
- Decreased lower esophageal sphincter tone
- Increased risk of difficult intubation
(Gastric fluid volume and Gastric emptying is the same as non-pregnant patients in pts not in active labor)
What are the hemodynamic goals of Intraoperative management of pregnant patients with Mitral/Aortic Valve Stenosis?
- Avoid tachycardia
- Maintain sinus rhythm
- Avoid marked decrease in SVR
- Avoid marked increase in blood volume
- Avoid increase in SVR
ACLS in pregnancy
- High-quality chest compressions and oxygenation
- Manual left lateral uterine displacement
- Defibrillation if rhythm is shockable
- if no ROSC w/in 4 minutes, perimortum C-section is advised
**IV access above level of diaphragm b/c compression of IVC
Main concerns w/ nonobstetric surgery in pregnant patients
Baby:
- Premature delivery
- Spontaneous abortion
- Premature labor
- Perinatal morbidity and mortality
Mom:
- Failed intubation
- Increased risk of aspiration
- Faster intake of anesthetics/decreased MAC for volatiles
- Supine hypotensive syndrome (aortocaval compression)
- *Nonurgent surgeries should be performed in 2nd trimester
- preterm contractions and spontaneous abortions are least likely
What factors influence fetal oxygenations?
Maternal oxygen tension, oxygen saturation, hemoglobin content, oxygen affinity, and uteroplacental perfusion
What premeds should be given to pregnant patients before non-obstetric surgery?
- Verbal anxiolytics, reassurance, and support
- If necessary, Benzos are ok
- Glycopyrrolate as vagolytic and antisialagogue
- Nonparticulate antacid (Sodium citrate)
- H2-receptor antagonist (Famotidine)
Effects of pregnancy on Nervous System
- Decreased MAC of inhaled anesthetics (30-40%)
- Increased sensitivity to local anesthetics
- Decreased volume of epidural anesthetics required 2/2 engorgement of epidural veins
- Also increased risk of intravascular injection
Technique for inducing GA for pregnant patient undergoing non-obstetric surgery
- Apply standard ASA monitors, ensure free flowing IV, use left uterine displacement, consider blood glucose monitoring for long procedures
- Pre-oxygenate for 3 minutes to endure denitrogenation
- Induce with RSI w/ cricoid pressure
- Maintain appropriate maternal oxygenation and normotensive BP to ensure uteroplacental perfusion
- Avoid hyper/hypoventilation
- Maintenance w/ volatile, fentanyl/morphine, non depolarizing NMB
- Reverse w/ Sugammadex or Neostigmine/Atropine
- Extubate trachea when patient is awake and regained laryngeal reflexes
What affect does GA have on FHR
Decrease in beat-to-beat variability
- 2/2 inhalation agents, opioids, and induction agents
When is it recommended to administer glucocorticoids for preterm delivery?
24-34 weeks
