J.Jpn. Surg. Soc.. 59(13): 2048-2060, 1959

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PULMOCIRCULATORY FUNCTION DURING SPINAL ANESTHESIA PART I. INFLUENCE ON THE RESPIRATORY FUNCTION

By means of metabulator the respiratory function during spinal anesthesia was clinically studied with hyperbaric and hypobaric anesthetics and the spinal anesthesia perfomed at a high level was compared to that at a low level. The results obtained were as follows :
1. The differences in the decreases of blood pressure and oxygen consumption were insignificant between the two anesthesias. However, the influence was greater in the high level anesthesia than in the low level anesthesia.
2. In both anesthesias, owing to peripheral paralysis of the respiratory muscles, the pulmonary ventilation decreased. The decrease was especially marked in the spinal anesthesia at an extra-high level when paralysis extended to the cervical cord.
3. During the usual spinal anesthesia with a hyperbaric solution, in which paralysis was confined to the cord lower than D₃, it was found that the oxygen equivalent was decreased and that the respiratory efficiency was maintained relatively fairly.
4. When an isobaric anesthetic was used, as compared with a hyperbaric anesthetic, the decrease in pulmonary ventilation was usually slight because of the compensatory function of the diaphragma. However, the oxygen intake was found to be not efficient, because an increase in oxygen equivalent was accompanied.
5. When the inspiratory reserve volume was compared between both solutions, the decrease was more marked with an isobaric solution than with a hyperbaric. Furthermore, the decrease was greater in the high level spinal anesthesia than in the low level spinal anesthesia.
6. With both solutions the expiratory reserve volume was markedly decreased and the relaxation of the abdominal musles, one of the features of the spinal anesthesia, was presented.
7. Pressor agents diminished oxygen equivalent in the cases in whom it had beer increased and substantially improved the efficiency of respiration.
8. To the respiratory disturbance during spinal anesthesia the supply of sufficient oxygen by assisted respiration with mask and bag was more reasonabl than the treatment with central excitants such as Theraptique and others.
(author's abstract)

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