Table 2.
Data on cardiopulmonary resuscitation (CPR) process received by patients with a cardiac arrest outside hospital: 233 patients during run-in phase of trial* and 1586 during evaluable period
| Run-in period (n=233) | Evaluable period | Difference of feedback-on from feedback-off | ||||
|---|---|---|---|---|---|---|
| Feedback-off (n=771) | Feedback-on (n=815) | Cluster adjusted difference (95% CI) | P value | |||
| Data for all available minutes | ||||||
| Minutes of data recorded: | ||||||
| Mean (SE) | 5.5 (0.3) | 5.6 (0.1) | 5.5 (0.1) | 0.1 (−0.2 to 0.5) | 0.481 | |
| Median (IQR) | 5 (0–10) | 6 (0–10) | 6 (0–10) | |||
| No of compressions/minute: | n=166 | n=570 | n=604 | |||
| Mean (SE) | 102.9 (1.6) | 108.0 (0.7) | 103.1 (0.5) | −4.7 (−6.4 to −3.0) | <0.001 | |
| Median (IQR) | 106 (93–116) | 109 (99–117) | 103 (96–110) | |||
| CPR fraction (%): | n=166 | n=570 | n=604 | |||
| Mean (SE) | 60.3 (1) | 64.0 (1) | 65.9 (1) | 1.9 (0.4 to 3.4) | 0.016 | |
| Median (IQR) | 61 (51–71) | 65 (56–73) | 67 (59–74) | |||
| Compression depth (mm): | n=86 | n=467 | n=529 | |||
| Mean (SE) | 34.3 (1.0) | 37.8 (0.4) | 39.6 (0.4) | 1.6 (0.5 to 2.7) | 0.005 | |
| Median (IQR) | 34 (27–42) | 37 (32–44) | 40 (35–44) | |||
| Compressions with incomplete release (%): | n=86 | n=467 | n=529 | |||
| Mean (SE) | 25.3 (2) | 14.6 (1) | 10.4 (1) | −3.4 (−5.2 to −1.5) | <0.001 | |
| Median (IQR) | 22 (7–40) | 8 (1–22) | 5 (1–14) | |||
| No of ventilations/minute: | n=24 | n=346 | n=347 | |||
| Mean (SE) | 4.9 (0.8) | 5.6 (0.2) | 5.8 (0.2) | 0.1 (−0.5 to 0.7) | 0.727 | |
| Median (IQR) | 6 (2–7) | 5 (2–8) | 5 (3–8) | |||
| No (%) of cases when feedback muted by EMS | 9 (5) | 6 (1) | 114 (14) | |||
| Data for the first five minutes of resuscitation | ||||||
| No of compressions/minute: | n=166 | n=561 | n=595 | |||
| Mean (SE) | 101.3 (2.1) | 107.3 (0.8) | 103.1 (0.6) | −3.9 (−5.9 to −2.0) | <0.001 | |
| Median (IQR) | 106 (91–116) | 108 (98–117) | 103 (96–111) | |||
| CPR fraction (%): | n=166 | n=562 | n=595 | |||
| Mean (SE) | 58.2 (1) | 61.9 (1) | 64.1 (1) | 2.3 (0.6 to 4.1) | 0.008 | |
| Median (IQR) | 61 (48–71) | 63 (54–72) | 66 (56–73) | |||
| Compression depth (mm): | n=81 | n=449 | n=509 | |||
| Mean (SE) | 35.6 (1.1) | 37.7 (0.5) | 39.7 (0.4) | 1.7 (0.6 to 2.9) | 0.003 | |
| Median (IQR) | 36 (29–43) | 37 (31–45) | 40 (35–45) | |||
| Compressions with incomplete release (%): | n=81 | n=448 | n=509 | |||
| Mean (SE) | 25.4 (3) | 14.6 (1) | 10.9 (1) | −2.9 (−4.9 to −0.8) | 0.007 | |
| Median (IQR) | 17 (2–47) | 7 (1–22) | 4 (1–14) | |||
| No of ventilations/minute: | n=22 | n=335 | n=335 | |||
| Mean (SE) | 4.3 (0.9) | 4.9 (0.2) | 5.2 (0.2) | 0.2 (−0.4 to 0.8) | 0.501 | |
| Median (IQR) | 4 (1–6) | 4 (2–7) | 5 (2–7) | |||
**Trial of CPR provided by emergency medical services with monitor-defibrillator providing real-time feedback on CPR process (“feedback-on”) or not providing feedback (“feedback-off”).
SE=standard error. IQR=interquartile range. EMS=emergency medical services.