RESPIRATORY FUNCTION DURING CERVICAL AND THORACIC EXTRADURAL ANALGESIA IN PATIENTS WITH NORMAL LUNGS

Lung volumes, expired gas volumes, tests of ventilatory capacityand blood-gas tensions were measured in women before and afterinduction of cervical or thoracic extradural analgesia using2% mepivacaine. Inspiratory capacity, vital capacity, totallung capacity and FEV₁, all decreased significantly 30 min afterboth cervical and thoracic extradural blocks. The changes observedduring cervical block were significantly greater than thoseobserved during thoracic extradural analgesia. Expiratory reservevolume and functional residual capacity decreased significantlyafter thoracic cxtradural block, but did not change after cervicalextradural block. Reduction in expired minute volume was observedin the two groups. Pa_co2 and alveolar-arterial oxygen tensiondifference increased, and Pa_co2 decreased significantly 25 minafter both blocks. These results demonstrate that pulmonaryventilation is slightly impaired by the two blocks and to thesame degree, but ventilatory reserve and capacity are markedlyimpaired by cervical extradural block. ^* Present address: Department of Anesthesiology, Shimane MedicalCollege and Hospital, Izumo City, Shimane-Ken, Japan.