Introduction
Materials and methods
Patients and setting
Primary exposure and covariates
Missing data
Outcomes
Statistical analysis
Results
Cohort characteristics
Characteristic
|
Overall
|
Non-survivors
|
Survivors
|
---|---|---|---|
(n = 170)
|
(n = 95)
|
(n = 75)
| |
Demographics
| |||
Age, years | 60 ± 16 | 59 ± 17 | 63 ± 15 |
Male sex | 89 (52%) | 54 (61%) | 35 (40%) |
Arrest characteristics
| |||
Out-of-hospital arrest | 96 (56%) | 58 (61%) | 38 (51%) |
Initial rhythm VT/VF | 64 (38%) | 31 (33%) | 33 (44%) |
Therapeutic hypothermia used | 113 (66%) | 76 (80%) | 37 (49%) |
Pittsburgh cardiac arrest category | |||
1 | 28 (16%) | 9 (9%) | 19 (25%) |
2 | 63 (37%) | 26 (27%) | 37 (49%) |
3 | 32 (19%) | 19 (20%) | 13 (17%) |
4 | 47 (28%) | 41 (43%) | 6 (8%) |
Baseline physiologic and ventilator data
| |||
First PaO2:FiO2 ratio | 241 ± 137 | 249 ± 129 | 231 ± 146 |
Dynamic compliance, mL/cm H2O | 29 ± 12 | 29 ± 12 | 28 ± 13 |
Initial SOFA-respiratory score | |||
0 | 26 (15%) | 13 (14%) | 13 (17%) |
1 | 33 (19%) | 24 (25%) | 9 (12%) |
2 | 33 (19%) | 17 (18%) | 16 (21%) |
3 | 46 (27%) | 26 (27%) | 20 (27%) |
4 | 32 (19%) | 15 (16%) | 17 (23%) |
Initial SOFA-cardiovascular score | |||
0 | 76 (45%) | 33 (35%) | 43 (57%) |
1 | 18 (11%) | 8 (8%) | 10 (13%) |
2 | 10 (6%) | 9 (9%) | 1 (1%) |
3 | 31 (18%) | 22 (23%) | 9 (12%) |
4 | 25 (21%) | 23 (24%) | 12 (16%) |
Cumulative vasopressor index | 1.4 ± 1.9 | 1.7 ± 1.9 | 1.1 ± 1.9 |
Time to first FiO2 wean, h | 6.3 ± 6.4 | 6.8 ± 6.9 | 5.8 ± 5.6 |
Number of FiO2 changes in 24 h | 2.5 ± 1.5 | 2.5 ± 1.6 | 2.6 ± 1.4 |
Outcome
|
Overall cohort
|
---|---|
(n = 170)
| |
Change in SOFA-respiratory score | |
0 to 24 h | −0.3 (1.5) |
0 to 48 h | −0.7 (1.4) |
0 to 72 h | −0.9 (1.5) |
Change in lung compliance, ml/cmH2O | |
0 to 24 h | 0.5 (13.9) |
0 to 48 h | 3.8 (18.4) |
0 to 72 h | 4.9 (21.0) |
Discharge CPC | |
1 | 8 (5%) |
2 | 1 (1%) |
3 | 58 (34%) |
4 | 7 (4%) |
5 | 94 (56%) |
Survival to hospital discharge | 75 (44%) |
Baseline predictor
|
B coefficient (95% CI)
|
P
-value
|
---|---|---|
Age | −0.035 (−0.069 to −0.001) | 0.04 |
Male sex | 0.438 (−0.658 to 1.535) | 0.43 |
Out-of-hospital arrest | 0.304 (−0.802 to 1.410) | 0.59 |
Arrest rhythm VT/VF | 1.306 (0.191 to 2.421) | 0.02 |
Received TH | 0.355 (−0.806 to 1.516) | 0.55 |
PCAC | ||
1 | Reference | Reference |
2 | −0.246 (−1.823 to 1.332) | 0.76 |
3 | 2.346 (0.548 to 4.143) | 0.01 |
4 | 0.441 (−1.217 to 2.100) | 0.60 |
First P:F ratio per 25 | −0.262 (−0.354 to −0.170) | <0.001 |
Initial pulmonary compliance | 0.010 (−0.035 to 0.054) | 0.67 |
Initial SOFA-respiratory score | ||
0 | Reference | Reference |
1 | 1.246 (−0.481 to 2.973) | 0.16 |
2 | 1.703 (−0.024 to 3.430) | 0.05 |
3 | 3.431 (1.815 to 5.047) | <0.001 |
4 | 4.279 (2.540 to 6.018) | <0.001 |
Initial SOFA-cardiovascular score | ||
0 | Reference | Reference |
1 | −1.190 (−3.040 to 0.660) | 0.21 |
2 | 0.145 (−2.230 to 2.519) | 0.90 |
3 | 1.092 (−2.230 to 2.600) | 0.15 |
4 | 1.245 (−0.197 to 2.686) | 0.09 |
Initial cardiovascular index | 0.346 (0.061 to 0.630) | 0.02 |
Time to first FiO2 wean | 0.012 (−0.074 to 0.099) | 0.78 |
Number of FiO2 changes in 24 h | −0.076 (−0.436 to 0.283) | 0.68 |
Pulmonary dysfunction
Predictor
|
Unadjusted odds ratio* (95% CI)
|
P
-value
|
---|---|---|
FiO2 AUC | 0.93 (0.86 to 1.02) | 0.11 |
Age | 1.00 (0.98 to 1.02) | 0.86 |
Male sex | 1.11 (0.62 to 2.00) | 0.72 |
Out-of-hospital arrest | 2.02 (1.11 to 3.67) | 0.02 |
Arrest rhythm VT/VF | 1.09 (0.78 to 2.00) | 0.78 |
Received TH | 2.74 (1.43 to 5.25) | <0.01 |
PCAC | ||
1 | Reference | Reference |
2 | 2.24 (0.88 to 5.70) | 0.09 |
3 | 0.87 (0.32 to 2.42) | 0.80 |
4 | 2.58 (0.97 to 6.84) | 0.06 |
Initial pulmonary compliance | 0.98 (0.95 to 1.01) | 0.24 |
Initial SOFA-cardiovascular score | ||
0 | Reference | Reference |
1 | 0.71 (0.27 to 1.85) | 0.48 |
2 | 1.88 (0.50 to 7.04) | 0.35 |
3 | 2.11 (0.93 to 4.77) | 0.07 |
4 | 1.02 (0.47 to 2.24) | 0.96 |
Initial CVI | 1.04 (0.90 to 1.20) | 0.62 |
Time to first FiO2 wean | 0.99 (0.95 to 1.03) | 0.67 |
Number of FiO2 changes in 24 h | 0.82 (0.68 to 0.99) | 0.04 |
Secondary outcomes
Baseline predictor
|
Odds ratio (OR)
|
P
-value
|
---|---|---|
Unadjusted OR (95% CI)
| ||
FiO2 AUC | 0.90 (0.82 to 0.98) | 0.02 |
Age | 1.02 (1.00 to 1.04) | 0.10 |
Male sex | 0.66 (0.19 to 1.22) | 0.19 |
Out-of-hospital arrest | 0.66 (0.36 to 1.21) | 0.18 |
Arrest rhythm VT/VF | 1.62 (0.87 to 3.03) | 0.13 |
Received TH | 0.24 (0.13 to 0.48) | <0.001 |
PCAC | ||
1 | Reference | Reference |
2 | 0.67 (0.26 to 1.72) | 0.41 |
3 | 0.32 (0.11 to 0.94) | 0.04 |
4 | 0.07 (0.02 to 0.22) | <0.001 |
First P:F ratio | 1.00 (1.00 to 1.00) | 0.38 |
Initial pulmonary compliance | 0.99 (0.97 to 1.02) | 0.68 |
Initial SOFA-respiratory score | 0.23 | |
0 | Reference | Reference |
1 | 0.38 (0.13 to 1.11) | 0.08 |
2 | 0.94 (0.34 to 2.63) | 0.91 |
3 | 0.77 (0.29 to 2.02) | 0.59 |
4 | 1.13 (0.40 to 3.19) | 0.81 |
Initial SOFA-cardiovascular score | <0.01 | |
0 | Reference | Reference |
1 | 0.95 (0.34 to 2.70) | 0.94 |
2 | 0.09 (0.01 to 0.71) | 0.02 |
3 | 0.31 (0.13 to 0.77) | 0.01 |
4 | 0.40 (0.17 to 0.92) | 0.03 |
Initial CVI | 0.82 (0.69 to 0.98) | 0.03 |
Time to first vent wean | 1.04 (1.00 to 1.10) | 0.08 |
Number of vent weans in 24 h | 0.79 (0.64 to 0.98) | 0.03 |
Adjusted OR (95% CI)
| ||
FiO2 AUC | 0.86 (0.76 to 0.97) | 0.02 |
Age | 1.01 (0.98 to 1.04) | 0.38 |
Male sex | 0.52 (0.23 to 1.18) | 0.12 |
Out-of-hospital arrest | 1.48 (0.52 to 4.23) | 0.46 |
Arrest rhythm VT/VF | 1.53 (0.62 to 3.77) | 0.35 |
Received TH | 0.19 (0.07 to 0.58) | <0.01 |
PCAC | ||
1 | Reference | Reference |
2 | 1.25 (0.33 to 4.79) | 0.74 |
3 | 0.91 (0.24 to 3.51) | 0.89 |
4 | 0.13 (0.03 to 0.58) | <0.01 |
Initial SOFA-cardiovascular score | ||
0 | Reference | Reference |
1 | 0.62 (0.14 to 2.69) | 0.52 |
2 | 0.05 (0.00 to 0.71) | 0.03 |
3 | 0.23 (0.04 to 1.31) | 0.10 |
4 | 0.12 (0.01 to 1.73) | 0.12 |
Initial CVI | 1.29 (0.73 to 2.26) | 0.38 |
Time to first vent wean | 0.78 (0.95 to 1.10) | 0.13 |
Number of vent weans in 24 h | 1.03 (0.58 to 1.07) | 0.49 |
Propensity score-adjusted analysis
Discussion
Conclusion
Key messages
-
Post-arrest patients are often exposed to 100% oxygen during cardiopulmonary resuscitation and the post-arrest period, raising concern for the potential for pulmonary oxygen toxicity.
-
This study suggests that higher oxygen exposure is not associated with subsequent pulmonary dysfunction after cardiac arrest.
-
At extreme levels, high oxygen exposure was associated with decreased survival to discharge, probably related to worsened neurological injury.
-
We suggest avoiding prolonged exposure to a FiO2 > 0.75 in the early post-arrest period unless necessary to prevent hypoxia.