The change over time of vital signs with consideration for opioid use in the last 2 weeks of life among cancer patients in a palliative care unit: Continuous measurement of vital signs using a non-wearable monitor

Objectives: The aim of this study was to examine the following by using a non-wearable monitor: (i) the trajectory of vital signs (VS) in the last 2 weeks of life among cancer patients, and (ii) the difference in change over time of VS between cancer patients with and without opioid use. Methods: We conducted a longitudinal study involving cancer patients in a palliative care unit (PCU) from April 2018 to October 2019. VS were collected continuously using a non--wearable monitor, and we calculated the means of respiratory rate (RR) and heart rate (HR) per hour, and counts of apnea per hour as outcome variables. Explanatory variables were time (subtracting time of death from measurement time of VS, divided by 36) and opioid use. Mean difference (MD) of time represented the slope per hour of VS values. First, we analyzed the associations between VS per hour and time using a linear mixed model (LMM) with random intercepts and slope over time. Second, we analyzed the associations between VS and interaction term between time and opioid use. Results: We analyzed 26 cancer patients. RR (MD: 0.27 beats/min [95% CI: 0.27-0.28]), HR (MD: 1.51 beats/min [95% CI: 1.50--1.52]), and apnea (MD: 0.71 count/ hour [95% CI: 0.70--0.72]) significantly increased hourly. In addition, RR was significantly associated with interaction term (MD: -1.59 beats/min [95% CI: -3.11 to -0.07]), which indicates that there is a difference in the slope of RR between opioid users and non--users. Conclusions: We have successfully described the trajectory of VS in high-resolution under conditions of a natural end of life in PCU.