Background: Respiration with mandibular movement (RMM) is one of the important clinical signs of impending death. However, there is very limited data on its natural course. Objective and Methods: This study was conducted in 23 inpatient palliative care units in Japan. It aimed to explore the natural course of RMM. Results: Among a total of 1526 cancer patients included, 1065 patients (69.8%) had RMM. A total of 14.8% patients experienced respiratory arrest within 30 minutes from RMM onset, 14.3% within 30-60 minutes, 34.4% within 1-4 hours, 17.5% within 4-12 hours, 8.9% within 12-24 hours, and 10.4%> 24 hours. Mean oxygen saturation and percentage of patients with SpO2 ≥90% at RMM onset were found to be significantly higher in patients with longer durations from RMM onset to death (p < 0.001). Conclusion: RMM occurred in a majority (80%) of dying patients within 12 hours. A minority of the patients survived >24 hours.
Keywords: cancer; death; palliative care signs; physical examination; respiration with mandibular movement.