Table 1 Baseline data for all subjects at the time of cardiac arrest
| Â | All subjects | Hypocapnia | Normocapnia | Hypercapnia |
|---|---|---|---|---|
n = 75 | n = 11 | n = 47 | n = 17 | |
Age (years (SD)) | 66 (16) | 71 (16) | 66 (16) | 62 (15) |
Female gender (n (%)) | 33 (44) | 7 (64) | 18 (38) | 8 (47) |
Pre-existing comorbidities (n (%)) | Â | Â | Â | Â |
 diabetes | 33 (44) | 4 (36) | 23 (49) | 6 (35) |
 known coronary artery disease | 18 (24) | 6 (55) | 8 (17) | 4 (24) |
 hypertension | 44 (59) | 9 (82) | 29 (62) | 6 (35) |
 malignancy | 17 (23) | 3 (27) | 11 (23) | 3 (18) |
 renal insufficiency | 16 (21) | 4 (36) | 10 (21) | 2 (12) |
 pulmonary disease | 22 (29) | 3 (27) | 11 (23) | 8 (47) |
 cerebral vascular disease | 2 (3) | 0 | 2 (4) | 0 |
 congestive heart failure | 10 (13) | 1 (9) | 6 (13) | 3 (18) |
Charlson comorbidity score [33] (median (IQR)) | 2 (1 to 4) | 3 (2 to 4) | 2 (1 to 4) | 2 (1 to 6) |
Arrest location (n (%)) | Â | Â | Â | Â |
 Out-of-hospital | 11 (15) | 0 | 6 (13) | 5 (29) |
 In-hospital | 64 (85) | 11 (100) | 41 (87) | 12 (71) |
Initial arrest rhythm (n (%)) | Â | Â | Â | Â |
 PEA/asystole | 56 (75) | 7 (64) | 35 (74) | 14 (82) |
 VF/VT | 19 (25) | 4 (36) | 12 (26) | 3 (18) |
CPR duration > 20 minutes (n (%)) | 9 (12) | 0 | 4 (9) | 5 (29) |