Pre-LTOT vs post-LTOT HRV
| HRV parameter | Period | Mean ± SEM | p Value* | |
| Pre-LTOT | Post-LTOT | |||
| RMSSDNN | Morning | 22.3±7.2 | 31.7±10.7 | 0.047 |
| SDNN | Morning | 25.4±6.1 | 31.3±8.0 | 0.039 |
| Total power | Night | 76.6±6.7 | 82.2±7.3 | 0.076 |
HRV, heart rate variability; LTOT, long-term oxygen therapy; RMSSDNN, square root of the mean of the sum of the squares of differences between adjacent NN intervals (NN refers to normal sinus rhythm RR intervals); SDNN, standard deviation of all NN intervals; total power, total frequency domain power within the analysed bandwidth (0.003–1.0 Hz).
*p values from paired t tests.