Obstetrical Anesthesia - Physiologic Changes in Pregnancy:
System
Changes
Cardiovascular
Increased cardiac output
Decreased systemic vascular resistance
Aortocaval compression – hypotension called by compression of the IVC by the gravid uterus
- As early as 13-16wks, more common closer to term
- Treat with left uterine displacement
Respiratory
Decreased functional residual capacity, results in rapid desaturations
Increased minute and alveolar ventilation
Increased O2 consumption
Decreased PaCO2, increased PaO2
Increased risk of airway edema, especially during labour
GI
Delayed gastric emptying during labour leads to increased risk of aspiration
Decreased lower esophageal sphincter tone
Hematologic
Increased total blood volume
Increase fibrinogen
Decreased anticoagulant activity and impaired fibrinolysis
Decreased platelet count
Decreased cholinesterase activity
Drug Response
Decreased inhalational anesthetic requirements with increased progesterone levels during pregnancy
Decreased local anesthetic requirements
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