Table 2.
Median values and ranges of each oximetry index and response pattern counts
| Cerebral oximetry index (n = 10) | |||||
| Dose | Baseline | Hypovolemia | Fluid resuscitation | ||
| Phenylephrine | SNP | Phenylephrine | Phenylephrine | SNP | |
| 0.5 | 0.05 (− 0.83 to 0.89) | 0.76 (0.10 to 0.97) | 0.36 (− 0.30 to 0.77) | 0.15 (− 0.51 to 0.85) | 0.77 (− 0.28 to 0.98) |
| 1 | − 0.41 (− 0.81 to 0.86) | 0.27 (− 0.20 to 0.97) | 0.27 (− 0.19 to 0.76)ǁ | 0.10 (− 0.42 to 0.67) | 0.70 (0.03 to 0.96) |
| 2 | − 0.21 (− 0.88 to 0.63) | 0.81 (0.34 to 0.96) | 0.12 (− 0.76 to 0.86) | − 0.03 (− 0.88 to 0.72) | 0.91 (0.31 to 0.96) |
| 5 | − 0.66 (− 0.93 to 0.92) | 0.93 (0.00 to 0.98)† | − 0.31 (− 0.87 to 0.71) | − 0.31 (− 0.85 to 0.79) | 0.95 (0.87 to 0.98)† |
| Response pattern counts (Pressure-passive/intact autoregulation/paradoxical response) | |||||
| 0.5 | 3/4/3 | 7/3/0 | 5/5/0 | 4/5/1 | 8/2/0 |
| 1 | 1/3/6 | 4/6/0 | 4/6/0 | 3/5/2 | 7/3/0 |
| 2 | 1/5/4 | 9/1/0 | 3/3/4 | 1/6/3 | 9/1/0 |
| 5 | 1/2/7 | 9/1/0 | 2/3/5 | 1/5/4 | 10/0/0 |
| Thoracic spinal cord oximetry index (n = 10) | |||||
| Dose | Baseline | Hypovolemia | Fluid resuscitation | ||
| Phenylephrine | SNP | Phenylephrine | Phenylephrine | SNP | |
| 0.5 | 0.44 (− 0.87 to 0.91) | 0.89 (0.76 to 0.96) | 0.75 (0.00 to 0.93) | 0.12 (− 0.82 to 0.79) | 0.89 (0.47 to 0.94) |
| 1 | 0.49 (− 0.85 to 0.86) | 0.80 (− 0.32 to 0.93) | 0.44 (− 0.24 to 0.92) | 0.25 (− 0.72 to 0.57) | 0.72 (− 0.50 to 0.89) |
| 2 | 0.57 (− 0.78 to 0.96) | 0.82 (0.25 to 0.89) | 0.78 (− 0.38 to 0.91) | 0.55 (− 0.64 to 0.87) | 0.83 (− 0.41 to 0.90) |
| 5 | 0.29 (− 0.57 to 0.82) | 0.80 (0.23 to 0.93) | 0.53 (0.06 to 0.87) | − 0.11 (− 0.85 to 0.60) | 0.84 (0.57 to 0.96) |
| Response pattern counts (Pressure-passive/intact autoregulation/paradoxical response) | |||||
| 0.5 | 6/3/1 | 10/0/0 | 8/2/0 | 4/4/2 | 10/0/0 |
| 1 | 5/2/3 | 8/2/0 | 6/4/0 | 2/6/2 | 9/0/1 |
| 2 | 7/1/2 | 9/1/0 | 7/2/1 | 7/2/1 | 9/0/1 |
| 5 | 5/4/1 | 9/1/0 | 6/4/0 | 3/3/4 | 10/0/0 |
| Lumbar spinal cord oximetry index (n = 9) | |||||
| Dose | Baseline | Hypovolemia | Fluid resuscitation | ||
| Phenylephrine | SNP | Phenylephrine | Phenylephrine | SNP | |
| 0.5 | 0.46 (− 0.88 to 0.92) | 0.86 (0.51 to 0.96) | 0.59 (0.12 to 0.80) | − 0.04 (− 0.19 to 0.68) | 0.87 (0.44 to 0.93) |
| 1 | 0.22 (− 0.87 to 0.83) | 0.45 (− 0.47 to 0.88)* | 0.46 (− 0.32 to 0.92) | 0.00 (− 0.34 to 0.58) | 0.68 (0.31 to 0.84) |
| 2 | 0.45 (− 0.90 to 0.97) | 0.80 (0.54 to 0.89) | 0.68 (− 0.39 to 0.92) | 0.45 (− 0.87 to 0.91) | 0.87 (0.61 to 0.94) |
| 5 | − 0.11 (− 0.99 to 0.63) | 0.75 (0.53 to 0.85) | 0.36 (− 0.33 to 0.97) | 0.02 (− 0.87 to 0.43) | 0.85 (0.65 to 0.97) |
| Response pattern counts (pressure-passive/intact autoregulation/paradoxical response) | |||||
| 0.5 | 5/2/2 | 9/0/0 | 6/3/0 | 4/5/0 | 9/0/0 |
| 1 | 4/2/3 | 5/3/1 | 5/4/0 | 2/7/0 | 8/1/0 |
| 2 | 7/1/1 | 9/0/0 | 6/2/1 | 5/3/1 | 9/0/0 |
| 5 | 2/5/2 | 9/0/0 | 5/4/0 | 2/4/3 | 9/0/0 |
Dose each vasoactive drug infusion dose (μg kg−1 min−1), SNP sodium nitroprusside. Response patterns were defined as follows: an oximetry index > 0.36 was defined as pressure-passive, an oximetry index between − 0.36 and 0.36 was defined as intact autoregulation, and an oximetry index < − 0.36 was defined as a paradoxical response
*P < 0.05 versus 0.5 μg kg−1 min−1; †P < 0.05 versus 1 μg kg−1 min−1; ǁP < 0.05 versus the same dose of phenylephrine infusion in the baseline condition