Abstract: After 30 patients of epidural bforking vein assisted with pethedine. Phenergan and meprobam-ate were observed, three of them were kept normal in SpO2 and PETCO2, but others in SpO2 were descended (P0.01): (93. 24 ± 4. 13) % with Pethedine and Phenergan; (93.40±1.14) % with Pedsdine, phenergan andmeprobamate. After operation, SpO2 in the formal two were retumed norma, but still low in the latter: (94.50±1.64) % (P 0.01). Affer assisted with the drugs, PETCO2 were obviously higher. 5.79 ± 0.69kPa in the formal two and 6.88 ± 1.48 kPa in the latter of which three drugs had been used together. The Paients didn' tbreathe well even with oxygen inhalation unil the operatio ended. Thus, it is suggested tha the patients of suchcase be assisted with face mask to avoid the occme of hypereatwa.