Applications of external cavity diode laser-based technique to noninvasive clinical diagnosis using expired breath ammonia analysis: chronic kidney disease, epilepsy

Abstract

An external cavity laser (ECL)-based off-axis cavity-enhanced absorption spectroscopy was applied to noninvasive clinical diagnosis using expired breath ammonia analysis: (1) the correlation between breath ammonia levels and blood parameters related to chronic kidney disease (CKD) was investigated and (2) the relationship between breath ammonia levels and blood concentrations of valproic acid (VAP) was studied. The concentrations of breath ammonia in 15 healthy volunteers, 10 epilepsy patients (before and after taking VAP), and 27 patients with different stages of CKD were examined. The range of breath ammonia levels was 120 to 530 ppb for healthy subjects and 710 to 10,400 ppb for patients with CKD. There was a statistically significant positive correlation between breath ammonia concentrations and urea, blood urea nitrogen, creatinine, or estimated glomerular filtration rate in 27 patients. It was demonstrated that taking VAP gave rise to increasing breath ammonia levels. A statistically significant difference was found between the levels of exhaled ammonia (NH3) in healthy subjects and in patients with epilepsy before and after taking VAP. The results suggest that our breath ammonia measurement system has great potential as an easy, noninvasive, real-time, and continuous monitor of the clinical parameters related to epilepsy and CKD.

Flexible Sensors Based on Conductive Polymers

“…Sources of NH 3 in the air are industrial manufacturing, automobile exhaust, animal husbandry or urea manufacturing for agricultural applications. NH 3 is also present in the human breath in small quantities (400-14,700 ppb) and its detection can be used as a noninvasive clinical diagnostic [99] of hepatic encephalopathy [100], end-stage renal disease (ESRD) [101], halitosis [102] orhelicobacter pylori inflection [103]. The most amply employed conductive polymers for gas sensors are polypyrrole and polyaniline.…”

Exhaled volatile substances mirror clinical conditions in pediatric chronic kidney disease

“…Up to now, different analytical techniques were applied to detect changes in breath profiles in this patient group. These techniques comprise hyphenated techniques such as GC-MS or direct MS able to identify and quantify large numbers of potential marker compounds, some others such as sensor technologies are better suited for point of care use and are still in early stages of development [6,11]. Despite these developments, data on exhaled volatile organic compounds in children are limited and refer to children with either inflammatory bowel diseases, chronic liver disease or respiratory diseases, while data on children with chronic kidney diseases are not available thus far [12–14].…”

Non-invasive detection of renal disease biomarkers through breath analysis

“…Breath ammonia levels decreased continuously during the dialysis treatment [59][60][61][62][63]. Bayrakli et al proposes that using a laser-based technique, specifically an external cavity diode laser, to measure breath ammonia shows potential as a non-invasive, real-time monitoring tool for epilepsy and CKD [64]. A wearable respiration sensor utilizing hydrogen plasma-treated CeO 2 @polyaniline nanocomposites exhibited enhanced detection of trace levels of ammonia in human breath.…”