Heart, respiratory rates speed up days before death in cancer patients

Respiratory rate (RR), heart rate (HR), and apnoea counts become more frequent during the last two weeks of life in cancer patients, according to a recent study. Such changes in vital signs (VS) may prove valuable for predicting impending death, especially with the help of monitoring devices, though potential modifying effects of opioid use need to be taken into consideration.

Although small, the changes in RR, HR, and count of apnoea per hour could be quantified using a nonwearable monitor, the researchers said.

“In the future, it is necessary to develop a system that can detect changes in RR, HR, and count of apnoea in real time; results from this study will serve as basic research for the potential development of such system,” they added.

A total of 26 cancer patients were followed in the present longitudinal study, all of whom were admitted to the palliative care unit. A nonwearable monitor device was used to continuously measure VS metrics, which were then used to calculate HR, RR, and apnoea counts per hour until death. The potential impact of opioid use on VS trajectories leading up to death was also assessed.

Linear mixed models showed that VS correlated significantly with the main time variable, which was calculated by subtracting the timepoint of death from the timepoint when the VS parameters were measured. For instance, RR increased as the time of death approached, an effect that remained significant even after controlling for age, sex, body mass index, and opioid use (mean difference [MD], 0.27 beats/min, 95 percent confidence interval [CI], 0.27–0.28). [Cancer Med 2021;doi:10.1002/cam4.4382]

The same was true for both HR (MD, 1.51 beats/min, 95 percent CI, 1.50–1.52) and apnoea counts (MD, 0.71 counts/hour, 95 percent CI, 0.70–0.72).

Notably, the researchers also observed a substantial impact of opioid use on end-of-life VS in cancer patients. In particular, the average RR (MD, –3.13 beats/min, 95 percent CI, –5.65 to –0.60) and HR (MD, –12.96 beats/min, 95 percent CI, –24.95 to –0.97) values of opioid users were significantly lower than their nonuser counterparts. Such an effect remained true at all time points measured.

Plotting the temporal trends of VS along a graph identified potential changing points in measurements. For instance, both HR and RR started showing marked increases 3 days before death. Apnoea counts, on the other hand, began its upward trend 11 days before death and showed slight dips 11 hours before death.

“This study suggested that RR, HR, and count of apnoea were important predictors of impending death for cancer patients,” the researchers said. “However, we should consider the effects of opioids when using RR as a predictor because the change over time in RR was different between opioid users and nonusers.”