NEPHROLUX™: Breath Ammonia Analyzer
Pranalytica is pleased to announce the availability of a research instrument, Nephrolux™, for detection of ppb level of ammonia in human breath. Nephrolux simultaneously measures the level of carbon dioxide in the breath. Presence of ammonia in exhaled breath has been linked to high levels of ammonia, ammonium ion, and BUN and creatinine in blood. Based on initial clinical studies carried out at UCLA's kidney dialysis center, Pranalytica has launched the availability of this product for research purposes.
Nephrolux, shown below, is in production, and is 66 cm tall, 56 cm wide, and 18 cm deep, weighing less than 40 kg, and consuming about 130 watts of 110V power. This version will also be available with a battery pack for field operation. The size of the instrument is such that it is ideally suited for bedside measurements of a patient's breath ammonia, which is a measure of a patient's nitrogenous compounds in the blood. Nephrolux consists of a sensitive gas analysis system and a facemask for collecting the patient's breath sample. A set of on screen instructions will walk the care giver/patient through an easy-to-use process for entering patient information, carrying out the breath collection and reviewing the results of the breath analysis. The instrument is designed expressly for use by non-technical personnel. It can be interfaced to the Internet through appropriate local area networks for logging data into a central data repository.
End Stage Renal Disease (ESRD) patients, individuals in whom there is a total renal failure, accumulate nitrogenous compounds such as blood urea nitrogen (BUN) and creatinine in their blood since the kidneys, which are normally expected to remove these waste products, have failed. For these individuals either a kidney transplant or regular dialysis (hemodialysis or peritoneal dialysis) are the only options. ESRD patients undergoing regular hemodialysis are generally treated three times a week for a fixed length of time, 2 to 5 hours, in each session. Efficacy of the urea removal is ascertained by calculating a Urea Reduction Ratio, derived by measuring the BUN at the start and end of a dialysis session and taking the ratio below:
This calculation requires taking blood samples and generally sending them to a lab for BUN and creatinine determination. Under normal circumstances, results are not available in less than12-48 hours. Thus URR measurements obtained this way have no meaningful impact on the treatment afforded to the patient in that specific session. Moreover, in the absence of routine measurements for each session, the dialysis center relies upon statistical evidence for its compliance with a minimum URR of 65%, which is gathered only once every month and averaged over several months. The real time derivation of URR for a patient undergoing dialysis would be instrumental in assuring both the patient and the physician of the adequacy of the treatment regardless of the change in the patient's life style from session to session. Using the correlation between breath ammonia concentration and BUN and creatinine published in the PNAS article (see the White Paper Section of the Web Page), Pranalytica has developed a surrogate for the URR, which we call the Breath Ammonia Reduction Ratio (BARR) given below. This ratio is derived from the measurements of predialysis breath ammonia and during dialysis breath ammonia concentrations, allowing caregivers to target a pre-determined BARR (a URR surrogate).
The Nephrolux is the first instrument that can measure the breath ammonia in real-time, at point of care, with a breath sampling time of less than two minutes. Thus the BARR data are available instantaneously. It may be possible to use the BARR for modifying or adjusting the treatment as appropriate.
As can be seen from the data obtained for one of the patients, BARR and URR track each other very well and thus a totally noninvasive real-time breath ammonia measurements can be a real-time, inexpensive, easy-to-usesubstitute for the blood-analyzed determinations of BUN and creatinie. Pranalytica will be submitting clinical data to the FDA for approval of the use of Nephrolux as a clinical adjunct to center-based as well home kidney dialysis treatments. For the latter situation, Nephrolux would become a necessary instrument for predicting the need for dialysis and for end-point detection, since traditional blood tests are not practical, even if the results were available in real time. Until such time as the FDA approval is obtained, Nephrolux is available only for research applications. For use in the clinical environment, the purchaser is expected to obtain an investigational device exemption from the FDA and appropriate Medical Independent Review Board approvals from relevant bodies if human studies are contemplated. A photograph of the Nephrolux in a kidney dialysis center environment is shown in the accompanying figure.
Prototype version of the Nephrolux placed in a dialysis center for extensive clinical trials (a Fresenius dialysis machine is seen in the background) has been in use since March 2001.
The production version of Nephrolux has received TUV certification (UL equivalent) recently