Heart rate variability (HRV) and baroreflex sensitivity (BRS) for 20 healthy volunteers before and after exposures to air and pollutants
| Measure | Time | Air | Carbon | SO2 | Carbon and SO2 |
|---|---|---|---|---|---|
| Normally distributed variables RR interval and mean arterial pressure (MAP) are mean (SEM). Non-parametric data are median (interquartile range). | |||||
| *p<0.05 for change from baseline with pollutant compared with change with air (repeated measures analysis). | |||||
| HF, high frequency; LF, low frequency; PNN50, percentage of successive RR interval differences exceeding 50 ms; RMSSD, root mean square of successive RR interval differences; SDNN, standard deviation of normal to normal RR intervals. | |||||
| RR (ms) | Baseline | 955 (21) | 984 (20) | 980 (25) | 973 (29) |
| 1 hour | 998 (22) | 1059 (23)* | 1017 (26) | 1034 (26) | |
| 4 hours | 907 (24) | 918 (23) | 902 (28)* | 924 (28) | |
| MAP (mm Hg) | Baseline | 85 (3) | 83 (3) | 82 (4) | 82 (4) |
| 1 hour | 84 (4) | 85 (3) | 84 (3) | 84 (3) | |
| 4 hours | 80 (3) | 84 (4) | 83 (4) | 80 (4) | |
| SDNN (ms) | Baseline | 26 (23–39) | 33 (24–41) | 33 (21–42) | 31 (24–39) |
| 1 hour | 34 (27–47) | 51 (34–69)* | 41 (27–68) | 41 (26–54) | |
| 4 hours | 26 (23–38) | 31 (23–37) | 26 (20–36)* | 30 (22–37) | |
| RMSSD (ms) | Baseline | 20 (15–28) | 25 (20–28) | 25 (17–38) | 19 (15–24) |
| 1 hour | 27 (19–33) | 40 (25–44)* | 26 (20–43) | 29 (21–38) | |
| 4 hours | 19 (15–26) | 19 (14–22) | 18 (9–25)* | 19 (15–22) | |
| PNN50 (%) | Baseline | 2 (0–6) | 5 (0–8) | 5 (1–14) | 2 (1–4) |
| 1 hour | 5 (1–10) | 19 (4–27)* | 7 (1–20) | 7 (2–14) | |
| 4 hours | 1 (0–4) | 1 (0–3) | 1 (0–4)* | 2 (1–3) | |
| HF power (ms2) | Baseline | 170 (125–355) | 267 (188–422) | 341 (160–622) | 181 (105–375) |
| 1 hour | 330 (183–528) | 749 (428–1209) | 213 (116–805) | 295 (195–753) | |
| 4 hours | 134 (88–364) | 195 (101–312) | 150 (50–419) | 137 (68–338) | |
| LF power (ms2) | Baseline | 68 (46–135) | 85 (42–141) | 65 (39–149) | 99 (57–118) |
| 1 hour | 165 (83–209) | 333 (194–516)* | 214 (72–676) | 141 (126–239) | |
| 4 hours | 106 (59–151) | 89 (56–135) | 70 (50–101) | 87 (53–194) | |
| α-HF (ms) | Baseline | 9.6 (6.3–9.9) | 8 (6.3–9.6) | 7.9 (6.0–10.1) | 6.3 (4.7–11.5) |
| 1 hour | 7.5 (7.0–10.2) | 9.2 (5.7–15.8) | 6.1 (5.0–10.2) | 8 (5.5–10.5) | |
| 4 hours | 6.7 (5.0–9.9) | 5.7 (5.1–7.1) | 4.4 (2.8–6.3)* | 4.7 (3.1–6.4) | |
| α-LF (ms) | Baseline | 4.7 (4.4–5.5) | 5.4 (4.5–9.1) | 7.9 (5.6–10.6) | 5.9 (5.1–6.4) |
| 1 hour | 6.1 (3.8–7.9) | 10.1 (6.1–14.7) | 6.9 (5.1–8.9) | 8.9 (5.3–10.2) | |
| 4 hours | 5.5 (3.4–8.5) | 5 (3.4–7.4) | 3.6 (2.5–4.1)* | 5.2 (3.8–9.3) | |