Physiological Considerations of Pregnancy
Anesthetic Considerations
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Airway
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Potentially more difficult laryngoscopy & intubation due to increased tissue edema & friability
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↑ Risk reflux & aspiration, especially after 20 weeks GA & even more during labor
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Respiratory
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↑ minute ventilation (50%), ↑ oxygen consumption (20%)
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↓ functional residual capacity (20%), at risk of rapid desaturation
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PaCO2 ~30
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Cardiovascular
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Supine hypotension can occur due to aorto-caval compression
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↑ Cardiac output, reaching a 40–50% ↑ by the third trimester. The largest increase occurs immediately after delivery. HR ↑ by 15-25%
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↓ Blood pressure due to ↓ in SVR
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Hematological
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Physiologic anemia of pregnancy due to disproportionate ↑ in plasma volume (45% at term) compared with erythrocyte volume (20% at term)
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Platelets usually normal unless gestational thrombocytopenia or other platelet disorders
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