Respiratory and Circulatory Changes During Spinal Anesthesia

Respiratory paralysis is the usual cause of immediate death from spinal anesthesia. Three mechanisms, or combinations of these, may be involved: Direct action on the medullary respiratory centers by diffusion of the drug to the fourth ventricle in paralytic concentrations. The observations of Koster and Kasman 1 and of Johnston and Henderson,2who demonstrated experimentally that excessively high concentrations are required to bring about this effect, indicate that this type can probably be excluded from serious consideration. Ascending block of the intercostal and phrenic nerves. This type of paralysis is unquestionably preventable and is secondary either to (a) ignorance of, or inexperience in, the technical aspects of the procedure, or to (b) unsuccessful attempts to produce a selective sensory nerve block of the neck and upper thoracic regions. Insufficient nutrient flow of blood through the central respiratory mechanism secondary to cardiovascular depression. Cardiovascular depression in some degree is attendant on