[Effect of potent analgesics on the ventilatory CO2 response and on the mouth occlusion pressure (author's transl)].

The depressant effects of four potent analgesics on the respiration were studied in 9 healthy young persons by determining the CO2 response (Read's method) and the mouth occlusion pressure (Whitelaw's method) before and after administration of the drugs and with or without interposition of additional inspiratory resistance (Rin). The analgesics tested were: Mr. 1268 = M1; pentazocine = M2; tramadol = M3; Mr. 1353 = M4. M1 and M2 induced a marked reduction in the ventilatory CO2 response (56.2 per cent +/- 21.8 for M1 and 53.8 per cent +/- 17.1 for M2). Interposition of Rin reduced the response to 43.9 per cent +/- 15.5 and 41.7 per cent +/- 17.3 respectively of the normal value. The occlusion pressure fell to 54.3 +/- 17 and 49.4 per cent +!- 22.2 respectively. After interposition of Rin the values were reduced 89 per cent +/- 27.3 and 79.9 +/- 29 respectively from the original value of 152.2 +!- 34.6. Administration of M3 or M4 did not significantly affect either the CO2 response or the occlusion pressure, nor had interposition of Rin any effect. M1 and M2 also induced changes in the ratio central stimulus P100/resultant flow (VT/Ti), viz.: M1 +/- SD: 77.1 per cent +/- 7.1; M2 +/- SD: 77.3 +/- 14.1. M3 and M4 had no significant effect M3 = 92.3 per cent +/- 9.1; M4 = 93.9 per cent +/- 13.3). The data indicate that the two methods make it possible to quantify that the two methods make it possible to quantify the respiratory depression induced by drugs and to differentiate between central respiratory depression and additional impairment of respiratory mechanics.