Obstetrics Flashcards
(33 cards)
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)
