International journal of obstetric anesthesia
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Recently, various authors have noticed and studied the phenomenon of ST segment depression during cesarean section. We have undertaken a review of the various postulated etiologies including venous air emboli, hormonal influences, autonomic nervous system influences tachycardia, postural influences, hypokalemia, hyperventilation, and myocardial ischemia. It appears that ST segment depression during cesarean section is almost certainly a multifactorial phenomenon. ⋯ Venous air emboli, hypokalemia, and hyperventilation probably have a minimal role. The sympatholysis produced by regional anesthesia is of unclear significance. It is important to note the apparent lack of morbidity associated with these changes.
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In a study of the factors involved in the occasional failure of continuous obstetric epidural blockade, contrast injections through epidural catheters and radiographic screening were undertaken in 35 postpartum patients. The two major causes of inadequate block were found to be transforaminal escape of the catheter tip, and persistent unilateral block associated with an obstructive barrier in the epidural space. Recommendations for overcoming these problems are discussed.