BackgroundPatients in the intensive care unit (ICU) often have limited ability to communicate making it more difficult to identify and effectively treat their pain. Family caregivers or close friendsof critically ill patients may be able to identifysigns of pain before the clinical care team, and could potentially assist in routine pain assessments. This study will adapt the Critical Care Pain Observation Tool (CPOT) for use by family members to create the CPOT-Fam and compare family CPOT-Fam assessments with nurse-provided CPOT assessments for a given patient.MethodsThis study will be executed in two phases:1) Development of the CPOT-Fam - A working group ofpatient partners, ICU clinicians, and researchers will adapt the CPOT for use by family caregivers (creating the CPOT-Fam) and produce an accompanying educational module to deliver information on pain and how to use the tool.The CPOT-Fam will undergo pre-clinical testing with participants (i.e., members of the public and family caregiversof critically ill adults), who will complete the educational module and provide CPOT-Fam scores on sample cases. Feedback on the CPOT-Fam will be collected.2) Pilot testing the CPOT-Fam – Family caregivers of critically ill adults will complete the educational module and provide information on: 1) demographics, 2) anxiety, 3) caregiving self-efficacy, and 4) satisfaction with care in the ICU. Family caregivers will then provide a proxy assessment of their critically ill loved one’s pain through the CPOT-Fam and also provide a subjective(i.e., questionnaire-based including open-ended responses) accountof their loved one’s pain status. A comparison (i.e., agreement) will be made between family caregiver provided CPOT-Fam scores and ICU nurse-provided CPOT scores (collected from the provincial health information system), calculated independently and blinded to one another. Feasibility and acceptability of the CPOT-Fam will be determined.DiscussionThe results of this work will produce a familycaregiver CPOT (i.e., CPOT-Fam), determine feasibility and acceptability of the CPOT-Fam, and comparepain assessments conducted by family caregivers and ICU nurses. The results will inform whether a larger studyto determine arole for family caregivers in ICU pain assessmentusing the CPOT-Fam is warranted.Trial registration- Not applicable.