Pain microcomputer system (PMS)

S119 EFFECT OF CHEMICAL SYMPATHECTOMY AND PGE INFUSION EVALUATED 138 Po BY P E R C U T A N E O U S OXYGEN T E N S I O N IN H Y P E R B A R I C OXYGEN CHAMBER Tuesday T.FUJITA, Y.KITANI. Dept. Anesthesiology, Gunma University Hospital, Maebashi, Gunma, JAPAN Aim of Investigation: Percutaneous oxygen tension(tcPo2) reflects tissue blood supply and it would evaluate the effect of sympathetic block for ischemic limbs. Because of thickness of skin, especially in lower limbs, it is, however, not always reliable in ambient room air. Therefore authors investigated tcPo2 in graded increments of inhaled oxygen tension from 150 to iSOOtorr in hyperbaric oxygen chamber. Methods: 32 cases with ischemic feet underwent lumbar chemical sympathectomy with 5% p h e n o l - g l y c e r i n by authors. On the sites of lowest temperature in thermogram, polarographic oxygen sensors, Dr~ger-Hellinge's Oxymonitor SM361 were applied. During increased inhaled oxygen tension from 150 to 1500torr, continuous tePo2 was measured before and after chemical sympathectomy. Further during infusion of PGEI 60gamma/hr the measurement was repeated. Results: Under the maximum inhaled oxygen tension of 1500tort, tcPo2 reached to 880torr in the mean for six healthy limbs, and it increased from 180 to 424torr before and after chemical sympathectomy. PGEI improved it to 643torr. There is obserw~d a linear correlation of increments of tePo2 for graded increase of inhaled oxygen tension when sympathetic block induced revascularization. Conclusion: It is reported all locations of tcPo2 less than 20torr should be amputated, however, even if ischemic pain relieved by our chemical sympathectomy, tcPo2 exhibited variable values in room air. Authors proclaim our new evaluation method and our sympathetic block supplemented by PCEI infusion precluded amputation. (PGEl:Prostaglandin El)

CRYOANALGESIA: THE RESPONSE TO ALTER,a, T I O N OF 139 Po TEMPERATURE A N D FREEZE CYCLE. P . J . D . Evans "1, 2, J.W. Tuesday Lloyd 1, C . J . Green *2. 1 Oxford Regional Pain Relief Unit, Ablngdon, Oxon, U . K . 2 Division of Comparative Medicine, MRC Clinical Research Centre, Harrow, Middlesex, U . K . Aim: This study explored the effects of altering both the temperature to which a nerve was frozen and the time and frequency of freezing on the period taken for nerve regeneration. Method: Male rats were anaesthetised and the left sciatic nerve was exposed. Four centlmetres proximal to the paw a cryolesion was produced using a Spembly BMS 40cryosurgical unit. The application of cold was for one or three minutes and in half the rats the freeze was repeated following an interval of two minutes. The cryoprobe temperature was controlled so that in each of the four main groups lesions were produced at specific temperatures between 0°C and -60°C. The return of motor and sensory function was monitored. Results: The production of the cryoleslon caused complete loss of function in the limb. The return of motor activity to the thigh was first noticed at 25 days (mean,) whilst return of power and reappearance of a response to a painful stimulus in the paw was noticed after 43 days (mean.) There was no differential effect and the findings were consistent with an axonal growth rate of 1 mm/day. The time taken for nerve regeneration was independent of both the duration of freezing and the application of a repeat freeze thaw cycle. The temperature attained by the nerve was important. Where it remained above -20°C the results were unpredictable. Below this temperature the interrupt ion was prolonged and not further influenced by reducing the tempo erature to -60 C.