Table 2. Blood gas and oxygenation variables (mean ± standard deviation) in six Beagle dogs before (baseline: BL) and during an infusion of saline as control (C), remifentanil at incremented doses of 0.15 (T1), 0.60 (T2) and 2.40 (T3) μg/kg/min (R), dexmedetomidine at 0.5 μg/kg/hr (D), or the combination of remifentanil and dexmedetomidine (RD) under sevoflurane anesthesia equipotent to 1.5 times of minimum alveolar concentration.
| Variable | Treatment | BL | T1 | T2 | T3 |
|---|---|---|---|---|---|
| pHa | C | 7.39 ± 0.02 | 7.37 ± 0.02 | 7.39 ± 0.01 | 7.38 ± 0.02 |
| R | 7.37 ± 0.03 | 7.37 ± 0.03 | 7.38 ± 0.04 | 7.35 ± 0.04 | |
| D | 7.37 ± 0.03 | 7.38 ± 0.02 | 7.39 ± 0.05 | 7.37 ± 0.03 | |
| RD | 7.37 ± 0.02 | 7.35 ± 0.04 | 7.34 ± 0.04 | 7.32 ± 0.04a) | |
| PaO2 (mmHg) | C | 562 ± 39 | 561 ± 47 | 564 ± 48 | 570 ± 47 |
| R | 560 ± 25 | 558 ± 30 | 559 ± 71 | 562 ± 35 | |
| D | 575 ± 40 | 578 ± 17 | 595 ± 23 | 573 ± 31 | |
| RD | 550 ± 45 | 571 ± 42 | 564 ± 40 | 559 ± 36 | |
| PaCO2 (mmHg) | C | 39.2 ± 3.7 | 39.8 ± 2.0 | 38.2 ± 2.5 | 38.3 ± 3.1 |
| R | 39.5 ± 3.3 | 40.0 ± 3.0 | 38.2 ± 5.9 | 39.8 ± 3.4 | |
| D | 39.3 ± 2.1 | 38.5 ± 1.2 | 37.0 ± 3.3 | 36.7 ± 2.2 | |
| RD | 40.7 ± 1.2 | 41.2 ± 3.3 | 41.2 ± 2.8 | 40.3 ± 2.3 | |
| HCO3− (mEq/l) | C | 22.7 ± 1.6 | 22.3 ± 1.0 | 22.2 ± 1.0 | 22.1 ± 1.4 |
| R | 22.2 ± 1.1 | 22.2 ± 1.1 | 21.4 ± 1.7 | 21.0 ± 1.2a) | |
| D | 22.2 ± 1.3 | 21.9 ± 0.9 | 21.4 ± 0.8 | 20.7 ± 1.3 | |
| RD | 22.6 ± 1.3 | 22.0 ± 1.5 | 21.5 ± 1.4 | 20.1 ± 2.1a) | |
| Base excess (mEq/l) | C | –2.3 ± 1.6 | –2.9 ± 1.2 | –2.8 ± 0.9 | –3.0 ± 1.4 |
| R | –3.0 ± 1.1 | –3.1 ± 1.3 | –3.8 ± 1.4 | –4.7 ± 1.5a) | |
| D | –3.1 ± 1.7 | –3.2 ± 1.2 | –3.6 ± 1.4 | –5.0 ± 2.5 | |
| RD | –2.8 ± 1.7 | –3.6 ± 2.0 | –4.2 ± 1.8 | –6.1 ± 2.7a) | |
| pHmv | C | 7.33 ± 0.02 | 7.32 ± 0.02 | 7.34 ± 0.02 | 7.33 ± 0.02 |
| R | 7.33 ± 0.02 | 7.32 ± 0.02 | 7.32 ± 0.04 | 7.32 ± 0.04 | |
| D | 7.33 ± 0.02 | 7.33 ± 0.03 | 7.33 ± 0.03 | 7.31 ± 0.04 | |
| RD | 7.32 ± 0.02 | 7.31 ± 0.06 | 7.30 ± 0.04 | 7.29 ± 0.05 | |
| PmvO2 (mmHg) | C | 63.7 ± 3.2 | 64.3 ± 1.5 | 66.0 ± 5.1 | 68.2 ± 5.5cd) |
| R | 67.5 ± 5.6 | 62.3 ± 3.9 | 61.8 ± 9.1 | 58.0 ± 8.0b) | |
| D | 65.5 ± 2.7 | 58.0 ± 4.5a) | 56.7 ± 5.4a) | 56.7 ± 6.1ab) | |
| RD | 65.7 ± 2.7 | 56.2 ± 6.6b) | 57.8 ± 4.6 | 53.3 ± 3.0ab) | |
| SmvO2 (%) | C | 87.6 ± 1.5 | 88.0 ± 0.7 | 88.5 ± 2.0 | 89.4 ± 2.0 |
| R | 89.1 ± 2.4 | 86.8 ± 2.3 | 85.9 ± 4.1 | 83.6 ± 5.5 | |
| D | 88.5 ± 1.2 | 84.2 ± 3.0a) | 83.1 ± 4.3a) | 82.9 ± 5.2 | |
| RD | 88.5 ± 1.3 | 82.6 ± 4.8b) | 84.1 ± 3.0 | 80.9 ± 2.3ab) | |
| Hct (%) | C | 32.3 ± 3.4 | 32.5 ± 3.8 | 32.2 ± 3.5 | 31.8 ± 4.0 |
| R | 32.8 ± 3.2 | 30.2 ± 0.4d) | 31.2 ± 2.6d) | 30.5 ± 3.3d) | |
| D | 32.5 ± 3.4 | 36.2 ± 2.9ac) | 37.2 ± 3.1ac) | 38.2 ± 3.0abc) | |
| RD | 32.5 ± 2.4 | 35.8 ± 3.3ac) | 37.0 ± 3.7c) | 37.8 ± 4.5c) | |
| Hb (g/dl) | C | 10.4 ± 0.8 | 10.8 ± 1.3 | 11.1 ± 1.3 | 11.2 ± 2.0 |
| R | 10.5 ± 0.8 | 10.1 ± 0.3d) | 10.3 ± 0.8d) | 10.3 ± 1.3 | |
| D | 10.8 ± 1.2 | 12.1 ± 1.2ac) | 12.5 ± 1.0ac) | 12.7 ± 1.1a) | |
| RD | 10.9 ± 0.6 | 12.0 ± 1.1c) | 12.3 ± 1.3c) | 12.5 ± 1.5 | |
| DO2I (ml/min/m2) | C | 443 ± 60 | 461 ± 48 | 479 ± 86 | 505 ± 90 |
| R | 481 ± 70 | 451 ± 79 | 484 ± 179 | 443 ± 192 | |
| D | 488 ± 41 | 404 ± 64 | 417 ± 76 | 437 ± 95 | |
| RD | 484 ± 75 | 378 ± 77 | 386 ± 104 | 357 ± 135 | |
| VO2I (ml/min/m2) | C | 91.5 ± 11.5 | 92.7 ± 11.2 | 91.9 ± 14.0 | 92.5 ± 11.4 |
| R | 99.2 ± 14.9 | 92.0 ± 10.5 | 102.5 ± 17.9 | 100.8 ± 19.5 | |
| D | 96.4 ± 8.8 | 92.0 ± 7.6 | 96.4 ± 10.1 | 97.9 ± 14.5 | |
| RD | 92.8 ± 12.9 | 90.0 ± 10.5 | 85.3 ± 11.0 | 85.3 ± 28.1 | |
| O2ER (%) | C | 20.7 ± 1.5 | 20.1 ± 1.0 | 19.4 ± 2.9 | 18.7 ± 2.9 |
| R | 19.1 ± 2.2 | 20.8 ± 3.4 | 22.2 ± 3.8 | 24.5 ± 5.3 | |
| D | 19.8 ± 1.1 | 23.1 ± 2.4 | 24.0 ± 3.7 | 23.8 ± 4.6 | |
| RD | 19.3 ± 1.3 | 24.5 ± 4.6 | 22.8 ± 3.4 | 24.3 ± 4.5 | |
pHa, arterial blood pH; PaO2, arterial blood oxygen partial pressure; PaCO2, arterial blood carbon dioxide partial pressure; HCO3−, arterial bicarbonate; pHmv, mixed venous blood pH; PmvO2, mixed venous blood oxygen partial pressure; SmvO2, mixed venous hemoglobin saturation; Hct, Hematocrit; Hb, Hemoglobin; DO2I, oxygen delivery index; VO2I, oxygen consumption index; O2ER, oxygen extraction. a) Significantly differ from respective baseline value (P<0.05); b) significantly differ from C treatment at this time point (P<0.05); c) significantly differ from R treatment at this time point (P<0.05); d) significantly differ from D treatment at this time point (P<0.05).