Table 2.
Blood variables from isoflurane-anesthetized horses (n = 5) breathing 50% or maximal oxygen concentrations
| Parameter | FiO2 | -5 min | 15 min | 30 min | 60 min | 90 min | 120 min | 150 min | 180 min | +10 min | Stand + 30 min |
|---|---|---|---|---|---|---|---|---|---|---|---|
| pHa | 50% | 7.446 ± 0.016 | 7.448 ± 0.014 | 7.461 ± 0.011 | 7.429 ± 0.008 | 7.409 ± 0.014 | 7.414 ± 0.016 | 7.424 ± 0.012 | 7.412 ± 0.016 | 7.375 ± 0.022 | 7.425 ± 0.011 |
| >95% | 7.428 ± 0.013 | 7.461 ± 0.031 | 7.437 ± 0.032 | 7.424 ± 0.027 | 7.431 ± 0.021 | 7.424 ± 0.018 | 7.432 ± 0.014 | 7.441 ± 0.017 | 7.386 ± 0.031 | 7.438 ± 0.005 | |
| PaO2 (kPa) | 50% | 12.06 ± 0.92 | 12.15 ± 1.24b | 12.55 ± 0.98b | 13.73 ± 01.16b | 13.48 ± 1.39b | 12.55 ± 1.54 | 10.89 ± 1.43 | 10.29 ± 1.48 | 5.60 ± 0.24 | 12.00 ± 0.35 |
| >95% | 12.07 ± 0.53 | 36.03 ± 4.02a,b | 32.13 ± 4.78a,b | 36.47 ± 5.93a,b | 34.18 ± 5.24a,b | 31.37 ± 6.32a | 29.20 ± 6.12 | 28.61 ± 6.34 | 5.92 ± 0.37 | 10.39 ± 1.07 | |
| Arterial Hb (g/dL) | 50% | 13.2 ± 1.7 | 12.4 ± 0.4 | 12.0 ± 0.5 | 14.1 ± 0.2 | 13.8 ± 0.2 | 13.5 ± 0.5 | 13.0 ± 0.7 | 12.8 ± 0.5 | 12.6 ± 0.3 | 11.8 ± 0.5 |
| >95% | 12.0 ± 0.5 | 11.9 ± 0.4 | 13.0 ± 0.6 | 13.7 ± 0.8 | 13.7 ± 0.3 | 13.6 ± 0.4 | 13.7 ± 0.7 | 13.3 ± 0.7 | 12.2 ± 0.6 | 11.5 ± 0.3 | |
| PaCO2 (kPa) | 50% | 4.84 ± 0.38 | 4.79 ± 0.30 | 4.63 ± 0.20 | 5.08 ± 0.08 | 5.53 ± 0.36 | 5.26 ± 0.25 | 5.11 ± 0.10 | 5.52 ± 0.32 | 6.76 ± 0.53a | 5.59 ± 0.23 |
| >95% | 5.36 ± 0.23 | 4.57 ± 0.45 | 5.25 ± 0.37 | 5.37 ± 0.38 | 5.39 ± 0.31 | 5.51 ± 0.16 | 5.57 ± 0.18 | 5.42 ± 0.26 | 6.70 ± 0.76 | 5.76 ± 0.20 | |
| PaHCO3 (mmol/L) | 50% | 26 ± 1 | 26 ± 0 | 26 ± 1 | 26 ± 0 | 26 ± 1 | 25 ± 1 | 25 ± 1 | 26 ± 1 | 27 ± 1 | 27 ± 1 |
| >95% | 27 ± 1 | 25 ± 1 | 27 ± 1 | 26 ± 1 | 27 ± 0 | 27 ± 1 | 28 ± 1 | 28 ± 1 | 28 ± 0 | 29 ± 1 | |
| SaO2 (%) | 50% | 96.3 ± 0.5 | 95.8 ± 0.8 | 96.4 ± 0.4 | 96.4 ± 0.5 | 96.2 ± 0.4 | 95.6 ± 0.9 | 94.7 ± 1.3 | 93.4 ± 1.8 | 81.5 ± 1.7a | 96.5 ± 0.2 |
| >95% | 96.8 ± 0.3 | 97.8 ± 0.1 | 97.6 ± 0.1 | 97.6 ± 0.2 | 97.6 ± 0.1 | 97.5 ± 0.2 | 97.4 ± 0.3 | 97.0 ± 0.7 | 84.0 ± 2.2a | 95.1 ± 0.9 | |
| pHv | 50% | 7.402 ± 0.010 | 7.418 ± 0.011 | 7.433 ± 0.008 | 7.408 ± 0.008 | 7.400 ± 0.011 | 7.398 ± 0.011 | 7.397 ± 0.013 | 7.392 ± 0.012 | 7.347 ± 0.015 | 7.387 ± 0.008 |
| >95% | 7.399 ± 0.006 | 7.422 ± 0.027 | 7.408 ± 0.027 | 7.401 ± 0.024 | 7.397 ± 0.020 | 7.398 ± 0.016 | 7.402 ± 0.015 | 7.407 ± 0.016 | 7.352 ± 0.019 | 7.397 ± 0.004 | |
| PvO2 (kPa) | 50% | 4.44 ± 0.41 | 4.44 ± 0.09 | 4.61 ± 0.12 | 5.55 ± 0.22 | 5.64 ± 0.14 | 5.34 ± 0.27 | 4.95 ± 0.33 | 4.85 ± 0.29 | 3.72 ± 0.18 | 3.74 ± 0.21 |
| >95% | 4.11 ± 0.10 | 4.96 ± 0.11 | 5.08 ± 0.16 | 5.88 ± 0.34a | 5.79 ± 0.43a | 5.71 ± 0.48a | 5.43 ± 0.35 | 5.32 ± 0.34 | 3.73 ± 0.19 | 3.59 ± 0.26 | |
| VLactate (mmol/L) | 50% | 0.5 ± 0 | 1.1 ± 0.1 | 1.2 ± 0.1 | 1.3 ± 0.1 | 1.4 ± 0.1a | 1.4 ± 0.1a | 1.5 ± 0.1a | 1.5 ± 0.1a | 1.4 ± 0.1a | 1.1 ± 0.2 |
| >95% | 0.5 ± 0.1 | 1.2 ± 0.1 | 1.4 ± 0.1 | 1.4 ± 0.1a | 1.3 ± 0.1 | 1.4 ± 0.1 | 1.5 ± 0.1a | 1.5 ± 0.1a | 1.4 ± 0.1a | 1.2 ± 0.5 |
Data are presented as mean ± standard error of the mean. pHa, arterial pH; PaO2, arterial partial pressure of oxygen; Arterial Hb, arterial hemoglobin; PaCO2, arterial partial pressure of carbon dioxide; PaHCO3, arterial bicarbonate; SaO2, arterial oxygen saturation; pHv, venous pH; PvO2, venous partial pressure of oxygen; vLactate, venous lactate. Time points: -5, 15, 30, 60, 90, 120, 150, and 180 represent min prior to and after induction of anesthesia; +10 min represents 10 min after disconnection from the anesthesia machine; and Stand +30 min represents 30 min after the horses stood in recovery.
a Within a treatment, value is significantly different than the -5 min value for this variable.
b Within this time point, value is significantly different than other treatment