This study aims to evaluate whether hyperkalemia, a potentially life-threatening condition in dialysis patients, can be detected early using a wearable single-lead ECG device. Patients with chronic kidney disease undergoing hemodialysis will wear a chest-attached ECG sensor (HiCardi) during dialysis sessions. ECG data will be collected four times over six weeks, in coordination with routine blood tests measuring serum potassium levels. The goal is to analyze changes in ECG waveforms, such as T waves, and determine if these correlate with elevated potassium levels. The study is non-interventional and observational, focusing on real-time, non-invasive monitoring. It is expected to improve clinical decision-making by enabling early detection of hyperkalemia without additional blood tests.

Inclusion Criteria:

• Adults aged 19 years or older
• Diagnosed with chronic kidney disease (CKD) and receiving maintenance hemodialysis three times per week
• Stable clinical condition without acute complications in the past 3 months
• Ability to understand and sign informed consent
• No physical or physiological barrier to wearing an ECG device

Exclusion Criteria:

• Significant skin conditions (e.g., severe dermatitis, burns) that prevent ECG device attachment
• Refusal or inability to comply with study procedures

Patients with chronic kidney disease undergoing regular hemodialysis at Chungnam National University Hospital. Participants are selected based on clinical stability and willingness to provide informed consent. The population includes both male and female adults without age restriction.

Individual participant data (IPD) will not be shared because the data include sensitive clinical and biometric information that may risk participant privacy. In addition, there is no current plan or infrastructure in place to support external data requests.