Global ageing is leading to an increase in cardiac arrest incidents among senior citizens, posing a significant societal challenge. Most out-of-hospital cardiac arrest (OHCA) incidents occur at home, limiting patients' immediate access to professional help and Automated External Defibrillators (AEDs). In such instances, Cardiopulmonary Resuscitation (CPR) by caregivers, often the patient's family with no expert knowledge of emergency care, becomes crucial. Compared to professional rescuers, caregivers could face challenges in executing effective CPR due to skill gaps and emotional barriers in performing such procedures on family members. This study investigates the emotional experience of caregivers in cardiac arrest scenarios, a critical but often overlooked aspect in the design of emergency care devices. We aim to understand 1) how emotions affect caregivers' performance and experience during domestic cardiac arrest incidents, and 2) how design can support their practical and emotional needs, enhancing their performance. Semi-structured interviews with professional rescuers and non-expert caregivers reveal the emotional challenges that caregivers might confront before, during, and after cardiac arrest incidents, such as fear of approaching a collapsed person, anxiety about causing harm, lack of confidence, and moral pressure from social ties. These challenges can lead to adverse reactions that further hinder their CPR performance. The study highlights the importance of including emotional support for non-expert rescuers in OHCA incidents. By incorporating human-centred design principles, we propose an inclusive design guideline for emergency care devices and practical design strategies to mitigate emotional barriers and assist operational performance for non-expert rescuers.