Learning objectives
- Describe the major physiological changes during pregnancy
- Describe the anesthetic implications of the physiological changes during pregnancy
Background
- Every major organ system is affected by substantial physiological changes during pregnancy
- Many of these changes significantly affect the pharmacokinetic and pharmacodynamic properties of different therapeutic agents, including anesthetics
- Understanding these changes and their effects is essential to optimize therapy and anesthesia in obstetric patients
Physiological changes
Anesthetic implications
Cardiovascular | Uterine perfusion not autoregulated |
Hypotension common under regional and general anesthesia | |
Supine hypotensive syndrome requires left lateral tilt | |
Respiratory | Potential hypoxemia in the supine and Trendelenburg positions |
Breathing more diaphragmatic than thoracic | |
Difficult laryngoscopy and intubation; bleeding during attempts | |
Central nervous system | More extensive local anesthetic spread |
Hematological | Dilutional anemia |
Thromboembolic complications | |
Edema, decreased protein binding of drugs | |
Gastrointestinal | Increased aspiration risk |
Antacid prophylaxis, RSI after 18 weeks gestation | |
Renal | Normal urea and creatinine may mask impaired renal function |
Glycosuria and proteinuria |
Suggested reading
- Costantine M. Physiologic and pharmacokinetic changes in pregnancy. Frontiers in Pharmacology. 2014;5.
- Nejdlova M, Johnson T. Anaesthesia for non-obstetric procedures during pregnancy. Continuing Education in Anaesthesia Critical Care & Pain. 2012;12(4):203-6.
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