ON THE PREVENTION OF THE BLOOD PRESSURE FALL DURING SPINAL ANESTHESIA IN THE RABBIT

When local anesthetics are introduced into the subarachnoid space to produce spinal anesthesia a fall in the blood pressure occurs, the extent of which depends largely upon the amount and type of anesthetic used and the technique of injection. Blood pressures of 50 mm. Hg and below have been recorded frequently (1, 2). The vasoconstrictor drug ephedrine has been used extensively as an adjuvant to spinal anesthesia since it was intro-duced for this purpose in 1927 simultaneously by Ockerblad and Dillon (3) and by Rudolf and Graham (4). It has been found to prevent the more severe falls in blood pressure. Holder (5) reported 151 cases in which he used ephedrine fifteen minutes before the spinal injection obtaining an aver-age fall in blood pressure of 12.8 mm. Hg ascompared with an average fall of 37.5 mm. Hg in a similar series of untreated cases. Lundy and Essex (6) found that 3 mgm. per kilogram was effective in raising a lowered pres-sure after spinal anesthesia in dogs. Lorhan and Oliverio (7) have recently reported promising results with neosynephrine. Epinephrine and pitressi