Obstetrics

Question 1

The Pregnant Patient

Considerations:

Answer 1

The Pregnant Patient

Considerations:

1. Anatomic and physiologic changes of pregnancy
2. Airway challenges:
   
   • Increased risk of difficult airway - friable & edematous
   • Rapid desaturation with apnea
   • Increased risk of aspiration
3. Prone to aortocaval compression
   
   • Requiring LLD positioning
4. Two patients - mother and fetus
5. Reduced MAC for volatile anesthetics

Question 2

Pregnancy Induced Hypertension/Pre-eclampsia

Considerations:

Answer 2

Pregnancy Induced Hypertension/Pre-eclampsia

Considerations:

1. Pregnant patient
2. Multisystem disease, main factors can include:
   
   1. Airway:
      
      • Increased friability & edema; even more difficult than baseline pregnant pt
   2. CNS:
      
      • Severe H/A
      • Cerebral edema, increased ICP
      • Seizures
      • Intracranial hemorrhage
   3. CV:
      
      • HTN; Increased SVR and potential for hypertensive crisis
      • Volume contraction
      • Hyperdynamic LV, potential for LV failure
      • Exaggerated pressor response
   4. Pulm:
      
      • Pulmonary edema
   5. GU:
      
      • Oliguria, ATN
   6. Heme:
      
      • Hyper- or hypo-coagulable
      • Thrombocytopenia
      • Potential for hemolysis and DIC
   7. Uteroplacental insufficiency
3. Antihypertensive therapy
4. Anticonvulsant therapy
5. Increased risk of fetal complications: IUGR, placental abruption, and premature delivery
   
   • MgSO4 for neuroprotection if gestational age < 32
   • Steroids if gestational age between 24 and 34 weeks

Question 3

PIH:

Pre-op Assessment: P/E

Answer 3

PIH:

Pre-op Assessment:

History:

1. Headache, visual changes, seizures?
2. Dyspnea?
3. Easy bruising, mucosal bleeding?
4. Anticonvulsant/antihypertensive use?

P/E

1. Vitals - including O₂ saturation (pulm edema)
2. Airway examination - anticipate difficulty 2^o to edema
3. CNS - mental status (altered?), focused neuro exam looking at pupilary size and reactivity, reflexes (hyperreflexia - sz, ICH, watch for hyporeflexia if on MgSO₄ therapy), movement of all limbs looking for focal neurological deficits
4. Hemodynamic status
   
   • Assess intravascular volume status: Orthostatic vitals (sitting & supine), JVP, capillary refill, gross temperature of the extremities, urine output
   • Assess for generalized edema
5. Resp - Auscultate lung fields for crackles, rales, rhonchi to r/o pulmonary edema
6. Coagulation status - bruises, petechiae, oozing around IV sites
7. GI - gently palpate the right upper quadrant for tenderness (liver involvement, subcapsular hematoma)

Question 4

PIH:

Pre-op Assessment: Investigations:

Answer 4

PIH:

Pre-op Assessment: Investigations:

Labs:

• Heme:
  
  • T & S, may crossmatch units
  • CBC, peripheral smear, LDH
  • Coags if plt <100,000: INR, PTT, fibrinogen
• Renal:
  
  • U/A, urine protein:creatinine ratio
  • Lytes, creatinine, BUN
• Hepatic: Transaminases, albumin
• Placenta: NST

Imaging:

• CXR (pulm edema), ECG
• If severe symptoms, or signs of heart failure or pulmonary edema, consider ECHO
• If neurological signs of ?stroke: CT heat
• NST: Looks for signs of decreased placental perfusion (decreased variability, bradycardia)
• Umbilical artery doppler assessment
• If mother stable, consider BPP

​

Question 5

PIH

Anesthetic Plan: 1) Optimization:

Answer 5

PIH

Anesthetic Plan: 1) Optimization:

• Antihypertensive Rx if BP> 160/110
  
  • Goal: SBP 120 - 160 mmHg
  • Goal DBP 80to 105 mmHg
  • Labetalol 20mg IV, then 20-40mmHg q10mins (max 220mg)
  • Hydralazine 5mg IV q20mins, max 20mg IV
  • If emergent, sodium nitroprusside 0.25 - 5.0 mcg/kg/min IV infusion (art line mandatory. Fetal risk of cyanide poisonning minimized if infused for <4h and dose <2mcg/kg/min)
• Seizure prophylaxis: MgSO₄
  • Loading dose: 4 to 6g over 20 to 30 mins
  • Maintenance infusion: 1 to 2g/hr
• Betamethasone to women between the gestational ages of 24 and 34 weeks
• Aspiration prophylaxis: Sodium citrate 30mL, ranitidine 50mL IV, metoclopramide 10mg IV
• Ensure replete intravascular volume: Consider fluid bolus prior to neuraxial technique, but BE CAREFUL as risk of volume expansion, dangerous if pulm/cerebral edema.

Question 6

PIH

Anesthetic Plan: 2) Options:

Answer 6

PIH

Anesthetic Plan: 2) Options:

Vaginal delivery: Epidural preferred

• To attenuated hypertension caused by pain
• May want to avoid epi in epidural solution
• Contraindications: Coagulopathy, plts < 70,000, signs of high ICP

C-section: Neuraxial preferred

• If no contraindications (above)
• Caution with spinal: rapid onset of sympathetic blockade may cause profound hypotension but little evidence for this. Pre-bolus IV fluid.
• GA if neuraxial contraindicated, poor maternal condition with CV/Pulm deterioration, or possibly severe fetal distress with anticipated easy airway

Question 7

PIH

How would you proceed with the anesthetic? : Set Up

Answer 7

PIH

How would you proceed with the anesthetic? : Set Up

Meds:

• Uppers and downers both important, but:
  
  • Uppers moreso with neuraxial - esp spinal - b/c BP could drop: Phenyl, ephedrine
  • Downers: esp. with GA b/c can have htn-ive crisis on induction and emergence: Labetalol, hydralazine, nitroprusside

Lines:

• Large bore IV access x2 (higher risk of PPH)
• Standard CAS monitors and 5-lead ECG
• Pre-induction art line
• Consider central line if pulmonary edema, severe cardiac disease

Airway:

• Preparations for difficult airway: variety of sizes of styletted ETTs esp. smaller tubes, difficult airway cart, adjuncts such as video laryngoscope and LMAs
• (AFOI if indicated)

Fetus:

• FHR monitoring

Other monitoring:

• Foley catheter
• Nerve stimulator

Question 8

PIH:

How would you proceed with the anesthetic?

Answer 8

PIH:

How would you proceed with the anesthetic?

If GA:

Induction:

• Consider AFOI if difficulty expected
• If not, RSI
• Prevent hypertensive response to laryngoscopy:
  
  • Fentanyl 3mcg/kg
  • Propofol 2mg/kg
  • Succinylcholine 1.5mg/kg
  • Labetalol 1mg/kg IV
  • Nitroprusside infusion started at 0.5mcg/kg/min
  • Lidocaine - I think it could lower the sz threshold, no would not give

Maintenance:

• Recognizing that pregnancy lowers MAC by 30% for inhalational agents:
• MAC 0.8 volatile until delivery
• At delivery, decrease volatile and add nitrous oxide
• Keep hemodynamics stable, avoiding HTN with nitroprusside infusion and anti-hypertensives mentionned earlier
• Recognize that there is an increased risk of hemorrhage at delivery which may lead to dramatic hypotension
• Keep Mg infusion running if it was onboard pre-op

Emergence:

• Long-acting opioid: dilaudid 2 to 3 mg then titrating more to RR prior to emergence
• If no hypotension intraop, give labetalol 10mg IV prior to emergence, titrate more as needed to keep SBP <160, DBP <105 as anesthetics turned off
• Vigilant monitoring of BP; ensure no hypertension
• Ensure pt is awake before removing ETT (increased aspiration risk)

Disposition:

• Risk of pulmonary edema after delivery due to previous IV hydration; consider diuresis
• Consider ICU as still at risk for severe complications, will need ongoing anti-hypertensive Rx and MgSO₄

Question 9

PIH: Potential Conflicts:

Answer 9

PIH: Potential Conflicts:

• Don’t use MgSO₄ in patients with myasthenia gravis; can precipitate myasthenic crisis
• Don’t use labetalol in patients with CHF or severe asthma or COPD
• Could use esmolol but be careful - causes fetal bradycardia, expect it
• Preeclampsia vs. fetal distress:
  
  • Approach depends on if difficult airway - AFOI?

Question 10

Eclampsia:

How would you manage it?

Answer 10

Eclampsia:

How would you manage it?

1. ​Immediate goals:

• Stop convulsions - diazepam
• Establish patent airway - turn pt to left, jaw thrust and O2 by facemask until sz stops, then BMV or assist-BMV if breathing starts
• Establish IV access, get vitals
• Anti-hypertensive Rx - labetalol or hydralazine
• MgSO₄ for further sz prevention
• Induction or augmentation of labour - in the absence of other indications, vaginal delivery is preferred

Also:

• Continuous FHR monitoring
• In eclampsia, get coags regardless of plt count

Question 11

Eclampsia:

What are your anesthetic options?

Answer 11

Eclampsia:

What are your anesthetic options?

• If the seizure has stopped and there are no recurrent seizures, and no other signs of increased ICP, you can do neuraxial anesthesia as long as coagulation OK.
• If pt is actively seizing, GA:
  
  • Technique similar to neuroanesthesia for high ICP
  • Fentanyl 4mcg/kg
  • Propofol 2mg/kg
  • Rocuronium 1.2mg/kg (potentiated by Mg)
  • Elevate head
  • Avoid hypoxemia, hypercarbia, hyperglycemia and hyperthermia (insert temp probe)