J Anesthesia for the pregnant patient undergoing a nonobstetric procedure
1. Introduction
b) Approximately 42% of procedures occur in the first trimester, 35% during the second, and 23% during the third.
c) Acute abdominal problems are most common, with appendectomy ranking first followed by cholecystectomy.
2. Preoperative assessment
a) Aortocaval compression becomes clinically relevant from approximately 20 weeks of gestation. It can be relieved by a left lateral tilt of 15 degrees, which is therefore essential in all pregnant patients in the supine position after 20 weeks.
b) There may be delay in the onset of the classical symptoms and signs of hypovolemia because of the increase in blood volume along with a resting tachycardia.
c) Pregnancy is a hypercoagulable state with an increase in most clotting factors. The platelet count may fall, but there is actually an increase in production and consumption.
d) Pregnancy is a significant risk factor for thromboembolism; therefore, thromboprophylaxis is essential in the postoperative period when the risk is further increased by immobility and the hypercatabolic state.
e) Airway management may be challenging during pregnancy. Bag-mask ventilation may be more difficult because of increased soft tissue in the neck. Laryngoscopy can be hindered by weight gain and breast engorgement. Increased edema of the vocal cords because of increased capillary permeability can hinder intubation and increase the risk of bleeding.
f) Increased maternal oxygen consumption and reduced functional residual capacity results in rapid oxygen desaturation during attempts at intubation.
i) It is recommended that from 16 weeks’ gestation, patients undergoing general anesthesia should be given prophylaxis against aspiration pneumonitis. This usually includes a nonparticulate antacid such as sodium citrate 0.3 M 30 mL and an H2 receptor antagonist (e.g., ranitidine 150 mg orally or 50 mg intravenously).
k) At the end of the procedure, the patient should be extubated fully awake in the lateral position.
3. Perioperative management
a) Fetal safety
(1) Prevention of fetal asphyxia
(a) One of the most serious risks to the fetus during maternal surgery is intrauterine asphyxia. This must be avoided by maintaining maternal oxygenation and hemodynamic stability.