Table 1 Characteristics and blood gas changes in 98 patients undergoing apnea test
From: The effect of incorporating an arterial pH target during apnea test for brain death determination
Variable | All patients (n = 98) | Positive AT (n = 89) | Inconclusive AT (n = 9) | P value |
|---|---|---|---|---|
Age (years), mean (±SD) | 50 (± 16) | 50 (± 16) | 52 (± 18) | 0.80 |
Female, n (%) | 54 (55) | 47 (53) | 7 (89) | 0.18 |
Primary etiology of BD, n (%) | ||||
 HIBI | 41 (42) | 35 (40) | 6 (67) | 0.31 |
 Nontraumatic ICH | 29 (30) | 29 (33) | 1 (11) | 0.26 |
 HIBI + Nontraumatic ICH | 3 (3) | 3 (3) | 0 | 1 |
 AIS | 11 (11) | 9 (10) | 2 (22) | 0.27 |
 TBI | 9 (9) | 9 (10) | 0 | 1 |
 Other cerebral edema | 5 (5) | 4 (4) | 1 (11) | 0.39 |
  Malignancy | 0 | 2 | 0 |  |
  Status epilepticus | 0 | 1 | 0 |  |
  Lupus cerebritis | 0 | 0 | 1 |  |
  Hemodialysis | 0 | 1 | 0 |  |
Duration between clinical exams (hours), mean (±SD) | 7 (± 9) | 6 (± 9) | 18 (± 11) | 0.03 |
Mean BP at the beginning of AT (mm Hg), mean (±SD) | ||||
 SBP | 127 (± 28) | 128 (± 28) | 113 (± 31) | 0.49 |
 DBP | 72 (± 16) | 73 (± 16) | 65 (± 17) | 0.50 |
 MAP | 90 ± 18 | 91 (± 18) | 81 (± 21) | 0.50 |
Temperature (°C), mean (±SD) | 36.9 ± 0.6 | 36.9 (± 0.7) | 36.9 (± 0.3) | 0.79 |
Vasopressor support, n (%) | 78 (80) | 71 (80) | 7 (78) | 1 |
Pre-AT blood gas (mm Hg), mean (±SD) | ||||
 pH | 7.38 ± 0.06 | 7.38 ± 0.06 | 7.37 ± 0.04 | 0.66 |
 PaO2 | 242 ± 130 | 246 ± 130 | 187 ± 127 | 0.37 |
 PaCO2 | 39 ± 5 | 39 ± 5 | 37 ± 5 | 0.37 |
Post-AT blood gas (mm Hg), mean (±SD) | ||||
 pH | 7.17 ± 0.07 | 7.17 ± 0.07 | 7.24 ± 0.04 | 0.01 |
 PaO2 | 234 ± 125 | 145 ± 120 | 47 ± 17 | < 0.01 |
 PaCO2 | 72 ± 13 | 73 ± 12 | 55 ± 9 | 0.01 |
Reasons for inconclusive test, n (%) | ||||
 Inadequate CO2 rise | 4 (4) | NA | 4 (44) |  |
 Inability to complete the test due to complication | 4 (4) | NA | 4 (44) |  |
 Unclear | 1 (1) | NA | 1 (11) |  |
Ancillary studies, total n (%) | 49 | 38 | 11 | < 0.01 |
 TCD | 18 (37) | 16 (42) | 2 (18) | 0.18 |
 SPECT | 14 (29) | 11 (29) | 3 (27) | 1 |
 EEG | 15 (30) | 10 (26) | 5 (45) | 0.28 |
 CTA | 2 (4) | 1 (3) | 1 (9) | 0.40 |