Losing harmonic stability of arterial pulse in terminally ill patients

To measure the coefficient of variation of the harmonic magnitude (HCV) of the radial arterial pulse before death of cancer patients.

We non-invasively recorded the radical arterial pulse of 21 end-stage cancer patients, 31 healthy subjects, and 47 outpatient department (OPD) patients. During the 2-week study, eight cancer patients expired.

There were no considerable differences in diastolic or systolic blood pressure between cancer patients and other subjects; however, all six HCVs were significantly higher in the cancer patients (P<0.05). Within the cancer patient group, the first and second HCV were notably higher in the patients that expired (P<0.05), and the first to fourth HCVs were significantly increased on their last day (P<0.05). In the control healthy subjects and the OPD group, the HCVs were below 5 and 8%, respectively. In the cancer patients, the third to sixth HCVs were higher than 15%. On the last day of the cancer patients that expired, even the first and second HCVs were higher than 15%.

During the dying process, the traditional diastolic and systolic blood pressure did not show significant changes; however, all the harmonic components gradually lost their stability. The HCVs, which increased first for the high-frequency components and then the low-frequency components, could quantitatively reflect the severity of different stages of illness.