Dynamic Breath VOC Profiling as a Non-invasive Tool to Assess Hemodialysis Adequacy

What is this study about? This is an observational study. The goal is to find out whether tiny chemicals in breath, called volatile organic compounds (VOCs), can help show if a hemodialysis session works well enough ("dialysis adequacy"). Hemodialysis is a treatment that uses a machine to remove waste and extra fluid from the blood.

Main questions Which breath chemicals change in people receiving hemodialysis when we compare samples collected before dialysis with samples collected after the same dialysis session? Do these changes help indicate whether a dialysis session is adequate (that is, whether it worked as intended)? How do the breath chemicals of people receiving hemodialysis differ from those of healthy adults? During the dialysis session, which blood test results go up or down? Which ones are most different from the usual healthy range? Who can take part Adults aged 18-85 years. Hemodialysis group: people with chronic kidney disease stage 5 who receive maintenance hemodialysis for at least three months.

Healthy comparison group: adults without major acute or chronic illnesses. Final eligibility will follow the approved study protocol and screening. What will happen if you join Hemodialysis group Provide one breath sample before a routine dialysis session and one breath sample after the same session.

Have a small blood draw at those same time points. Your usual medical care will not change because of this study. Healthy comparison group Provide one breath sample and one small blood draw at a single visit. Time and visits For people receiving hemodialysis: both breath and blood samples are collected around one dialysis session (before and after).

For healthy adults: all procedures are finished in one scheduled visit. The study plans to include about 22 people on hemodialysis and about 23 healthy adults. These numbers may change slightly as enrollment proceeds.

How your samples are used Breath samples will be analyzed with gas chromatography-mass spectrometry (GC-MS), a laboratory method that separates and identifies very small amounts of chemicals in breath.

Blood samples will be tested for routine biochemistry and immune measures to see which results change during dialysis and which results are different from the healthy range.

The study does not test a new drug or device and does not change your treatment.

Possible benefits You may not receive a direct benefit. The knowledge from this study may help doctors find simple, non-invasive ways to judge whether dialysis works well, which could improve care for people with kidney failure in the future.

Possible risks or discomforts Breath collection is non-invasive and usually causes no discomfort. Blood draws may cause brief pain, a small bruise, or lightheadedness in some people.

Privacy and data protection We label samples and data with codes instead of names. Only authorized staff can link the codes to your identity.

Study results may be published in journals or at meetings, but no information that can identify you will be shared.

Where and when Location: Shanghai Second People's Hospital (Department of Nephrology, Dialysis Unit).

Study period: September 1, 2025 to June 30, 2027. Sampling is expected during routine care for people on dialysis and during one visit for healthy adults.

Study team Principal Investigator: Tao Xiaoyang, Shanghai Second People's Hospital.