Question

Spinal anesthesia to a T4 level would be expected to cause

A. A decrease in dead space
B. An increase in Pa co2
C. Dyspnea due to hypoxemia
D. A decrement in active exhalation
E. Impairment in diaphragmatic function

Answer 1

Spinal anesthesia at the T4 level would most likely cause impairment in diaphragmatic function, as it may affect the chest wall and intercostal muscles which are necessary for efficient breathing.

Step-by-step explanation:

Spinal anesthesia to a T4 level could be expected to cause an impairment in diaphragmatic function. This is because the nerves that control the diaphragm originate from the C3 to C5 levels of the spinal cord, and while T4 level anesthesia may not directly impact these nerves, it could potentially affect the chest wall and intercostal muscles crucial for effective respiration. Consequently, paralysis at and below the T4 level could compromise the contribution of these muscles to breathing, reducing the efficiency of deep breaths and possibly causing dyspnea. However, it would not typically cause an increase in physiological dead space or PaCO2, nor would it significantly alter intrapleural pressure to prevent inhalation or directly slow expiration, as the primary function of active exhalation is not mediated by the diaphragm.