  Pain and physical function are both essential indices of recovery in
critically ill patients in the Intensive Care Units (ICU). Simultaneous
monitoring of pain intensity and patient activity can be important for
determining which analgesic interventions can optimize mobility and function,
while minimizing opioid harm. Nonetheless, so far, our knowledge of the
relation between pain and activity has been limited to manual and sporadic
activity assessments. In recent years, wearable devices equipped with 3-axis
accelerometers have been used in many domains to provide a continuous and
automated measure of mobility and physical activity. In this study, we
collected activity intensity data from 57 ICU patients, using the Actigraph
GT3X device. We also collected relevant clinical information, including nurse
assessments of pain intensity, recorded every 1-4 hours. Our results show the
joint distribution and state transition of joint activity and pain states in
critically ill patients.
