Anesthesia for Obstetrics and Gynecology - Maternal Physiology in Pregnancy (Table 32.1)
- Capillary engorgement of the mucosa may occur throughout the respiratory tract, beginning early in the first trimester and increasing throughout pregnancy. Historically, a 6.0- to 6.5-mm (inner diameter) endotracheal tube has been recommended for intubation to decrease the possibility of airway trauma. However, the use of larger tubes may be possible in most patients should it be required. Fluid retention may lead to an enlarged tongue that may explain the increased prevalence of Mallampati class 3 and 4 airways in term parturients compared to the general population. Additionally, the airway exam may change during the course of labor resulting in a further increase in the airway class. Lastly, because of mucosal engorgement, nasotracheal intubation may cause epistaxis and is best avoided in pregnant women.
- Minute ventilation increases by 45% to support the higher oxygen requirements of the mother and fetus and is driven by a proportional increase in tidal volume. As the pregnancy progresses, elevation of the diaphragm from the gravid uterus leads to 20% decrease in maternal functional residual capacity. The resultant decrease in oxygen reserve mandates adequate preoxygenation prior to induction of general anesthesia.
There's more to see -- the rest of this topic is available only to subscribers.