Table 2.
Hemodynamic parameters and selected results from blood gas analyses during the measurement of cerebrovascular autoregulation (CVA)
| No early hypercapnia (n = 27) | Early hypercapnia (n = 39) | |
|---|---|---|
| Measurement periods = 47 | Measurement periods = 70 | |
| Time with impaired CVA (%) | 27.45 ± 18.51 | 22.95 ± 18.75 |
| Duration of measurement (min) | 77 ± 12 | 77 ± 15 |
| Time with impaired CVA (min) | 21 ± 15 | 18 ± 15 |
| Cerebral oxygenation index COx | 0.11 ± 0.15 | 0.06 ± 0.18 |
| Regional cerebral oxygen saturation rSO2 (%) | 59.81 ± 12.03 | 67.32 ± 10.20 |
| Mean arterial blood pressure (mmHg) | 76.34 ± 10.84 | 74.85 ± 9.12 |
| Heart rate (bpm) | 81.25 ± 18.80 | 90.45 ± 19.10 |
| Body temperature (°C) | 37.1 ± 0.8 | 37.1 ± 0.9 |
| Hemoglobin (mg dl−1) | 9.20 ± 1.42 | 9.79 ± 1.63 |
| PaO2/FiO2 ratio | 152.55 ± 57.16 | 151.38 ± 75.27 |
| Mean PaO2 (mmHg) | 80.6 ± 18.4 | 85.9 ± 16.4 |
| Mean PaCO2 (mmHg)a | 45.2 ± 11.1 | 47.7 ± 9.6 |
| Hypocapnia (< 35 mmHg)b | 8 (17) | 3 (4.3) |
| Normocapnia (35–50 mmHg)b | 28 (59.6) | 43 (61.4) |
| Hypercapnia (> 50 mmHg)b | 11 (23.4) | 24 (34.3) |
| pH | 7.41 ± 0.08 | 7.39 ± 0.09 |
| Lactate (mmol/L) | 1.6 ± 0.9 | 2.3 ± 2.5 |
| Δ PaCO2 (mmHg)c | 1.29 ± 1.76 | 1.79 ± 3.23 |
| Δ pHc | 0.01 ± 0.02 | 0.01 ± 0.02 |
| Δ PaO2/FiO2 ratio (mmHg)c | 8.20 ± 12.86 | 9.86 ± 19.73 |
| Isoflurane (ml/h) | 6.5 ± 4.5 | 6.8 ± 4.1 |
| Isoflurane (end-tidal concentration in %) | 1.1 ± 0.4 | 1.2 ± 0.3 |
| From ARDS diagnosis until first CVA measurement | ||
| Time from ARDS diagnosis to first measurement (days) | 4 ± 4 | 2 ± 2 |
| Mean PaCO2 (mmHg) | 41.6 ± 8.6 | 47.8 ± 17.9 |
| PaCO2 variabilityd (mmHg) | 32.1 ± 40.3 | 115.1 ± 168.8 |
| From first until second CVA measurement | ||
| Time from ARDS diagnosis to second measurement (days) | 8 ± 3 | 5 ± 3 |
| Mean PaCO2 (mmHg) | 49.2 ± 10.9 | 49.0 ± 7.3 |
| PaCO2 variabilityd (mmHg) | 68.6 ± 65.2 | 57.8 ± 50.2 |
Mean values from monitoring episodes 1 and 2, stratified by the presence of early hypercapnia. Data are given in n (%) or mean ± SD
COx cerebral oxygenation index as a surrogate of cerebrovascular autoregulation
a“Mean PaCO2” refers to the statistical mean of two blood gas analyses during one CVA monitoring episode
bPaCO2 was categorized as “hypocapnia”, “normocapnia”, and “hypercapnia” during each measurement period
cΔ values refer to the mean difference between the first and the second CVA measurement in one study participant
dCalculated as the variance