Anesthetic Considerations in Pregnant Patients with Pulmonary Disorders

Abstract

The neuraxial blocks vary in distribution and intensity, depending on the clinical requirements. For example, the afferent pain signals for the first stage of labor (cervical dilation) enter the spinal cord through the T10 to L1 spinal nerve roots (Figure 8.1). In the second stage of labor, additional afferent pain signals arrive via the S2 to S4 spinal nerve roots. Therefore, the ideal neuraxial labor analgesic would be distributed at and below the T10 dermatome, which corresponds to the umbilicus. Based on empiric observations, patient comfort during a cesarean delivery requires an anesthetic neuraxial block that extends cephalad to at least the T4 dermatome, which corresponds to the nipple line. Analgesic and anesthetic blocks differ in the intensity of sensory and motor effects. An analgesic block is characterized by a sensation of light touch when a sharp object is lightly applied to the block area. In contrast, an anesthetic block is ‘‘more dense’’ and characterized by the absence of sensation when a sharp object is lightly applied to the block area. Based on distribution and intensity, a neuraxial anesthetic for cesarean delivery is more likely to have an impact on pulmonary function compared to a neuraxial labor analgesic. Whenever it is clinically feasible, most anesthesiologists and patients prefer neuraxial over general anesthesia in obstetrics, to maximize safety and birth experience satisfaction. For example, general anesthesia for cesarean delivery is usually limited to those situations where neuraxial anesthesia is contraindicated (Table 8.1), or when