Introduction
Methods
Patient population and initial stabilization
Monitoring
Study protocol
Statistical analysis
Results
Demographic data
Ventilation parameters
n = 11 | A Baseline | B Minute ventilation | C Moderate hyperventilation | D 50 min of moderate hyperventilation | E Return to baseline |
---|---|---|---|---|---|
etCO2 (kPa) | 5.0 (0.7) | 4.3 (0.6)* | 4.2 (0.6)*§ | 4.0 (0.7)*§ | 4.7 (0.7)*§¶Ŧ |
MV (L/min) | 6.9 (1.4) | 8.6 (1.6)* | 8.7 (1.7)* | 8.4 (1.5)* | 6.8 (1.4)§¶Ŧ |
pH | 7.37 (0.09) | 7.45 (0.02)* | 7.46 (0.03)*¶ | 7.41 (0.03)¶Ŧ | |
PaCO2 (kPa) | 5.0 (0.2) | 4.3 (0.2)* | 4.1 (0.4)*¶ | 4.7 (0.4)*¶Ŧ | |
PaO2 (kPa) | 17.2 (1.5) | 17.9 (1.9) | 18.8 (2.3)*¶ | 17.4 (1.2)Ŧ |
Effects of hyperventilation on systemic and cerebral hemodynamics
n = 11 | A Baseline | B Minute ventilation | C Moderate hyperventilation | D 50 min of moderate hyperventilation | E Return to baseline |
---|---|---|---|---|---|
HR (beats/min) | 72 (16) | 72 (17) | 71 (17) | 71 (17) | 66 (16) |
MAP (mmHg) | 92 (10) | 92 (10) | 93 (12) | 90 (10) | 94 (13) |
ICP (mmHg) | 16 (6) | 8 (5)* | 8 (6)* | 10 (7)* | 14 (6)§¶Ŧ |
CPP (mmHg) | 77 (9) | 84 (9)* | 85 (10)* | 81 (14) | 80 (11)§¶ |
PbrO2 (mmHg) | 32 (10) | 33 (9) | 33 (10) | 30 (8)§¶ | 30 (8)§ |
Effects of hyperventilation on mean flow velocity and PI in the middle cerebral artery
n = 11 | A Baseline | C Moderate hyperventilation | D 50 min of moderate hyperventilation | E Return to baseline |
---|---|---|---|---|
CBFV right (cm/s) | 81 (23) | 69 (21)* | 71 (20)* | 77 (28) |
CBFV left (cm/s) | 80 (22) | 66 (17)* | 63 (15)* | 75 (24)¶Ŧ |
PSV right (cm/s) | 136 (37) | 117 (34)* | 120 (33)* | 129 (42) |
PSV left (cm/s) | 131 (35) | 110 (25)* | 107 (24)* | 126 (37)¶Ŧ |
EDV right (cm/s) | 56 (20) | 45 (16)* | 46 (16)* | 51 (22)¶ |
EDV left (cm/s) | 54 (16) | 43 (13)* | 41 (11)* | 52 (17)¶Ŧ |
PI right | 1.03 (0.17) | 1.08 (0.16) | 1.05 (0.23) | 1.05 (0.17) |
PI left | 0.96 (0.15) | 1.06 (0.10) | 1.07 (0.14)* | 1.02 (0.14) |
Brain tissue oxygen tension and cerebral metabolism
n = 9 | Baseline (A − 1 h) | 1 h after moderate hyperventilation for 50 min (D + 1 h) | 2 h after moderate hyperventilation for 50 min (D + 2 h) |
---|---|---|---|
Brain glucose (mmol/L) | 1.5 (1.0)Φ | 1.4 (0.7) | 1.4 (0.7) |
Brain lactate (mmol/L) | 3.3 (1.0)Φ | 3.5 (1.3) | 3.4 (1.4) |
Brain pyruvate (μmol/L) | 101.4 (38.3)Φ | 99.6 (39.5) | 97.3 (44.7)Φ |
LP ratio | 34.2 (8.2)Φ | 39.0 (17.7) | 37.5 (11.4)Φ |