Additional Information

Background: Dx–pH Measurement System

The Dx–pH Measurement System is a revolutionary system that comfortably measures pH in the upper airway.  Until now it has been difficult to detect reflux in the upper airway because available pH catheters were developed to measure liquid reflux in the esophagus.

Gastric reflux in the upper airway, or LaryngoPharyngeal Reflux (LPR), commonly takes a gaseous form that cannot easily be measured using conventional technology.  The miniaturized pH sensor at the tip of the Dx–pH Probe is the only sensor able to measure pH in the upper airway.

By measuring pH levels in the upper airway, the Dx–pH System is a valuable tool to assist in determining the existence of LPR and its relationship to various patient symptoms.

Frequently Asked Questions: Dx–pH Measurement System

What is the purpose of this test?  What information will be gained and how will it guide treatment?

• The information provided by the Dx-pH Measurement System is important in determining the impact of LaryngoPharyngeal Reflux (LPR) on a child’s symptoms.  This test provides a graphical representation of the pH activity over a 24 or 48-hour study.  This data is valuable as it relays information about the patient’s LPR patterns in a clear fashion.  Some ask why this is better than laryngoscopy; with laryngoscopy, the physician can evaluate the severity of tissue damage but cannot determine whether it is the result of LPR, vocal strain, coughing, or another source.

What clinical evidence is available to confirm that the Restech system works in the upper airway compared to traditional pH sensors used to measure pH above the UES?

• Studies conducted with conventional pH catheters placed above the upper esophageal sphincter (UES) have demonstrated repeated failure for reliable pH measurement because conventional pH testing is dependent on immersion in liquid to read pH.  Until now, a self-condensing sensor (one that does not require immersion in liquid) was not available.  When reflux is aerosolized, conventional pH sensors are incapable of reliably measuring the pH.  Restech’s Dx–pH Probe contains a miniature sensor that rests in the tip of a teardrop-shaped catheter.  The unique shape keeps the sensor pointed down where it reads the aerosolized reflux.  Due to the unique configuration and positioning of the pH sensor, Restech has virtually eliminated the problem of false negatives.

How well tolerated is the Dx–pH Probe?

• The Dx–pH Probe is tolerated very well by children in most everyday circumstances.  Because it rests well above the epiglottis, the swallowing mechanism is not interrupted.  Aside from keeping the transmitter and receiver dry, there are no restrictions in the child’s eating, drinking, or activity level.

Can the probe be placed deeper in the airway, or in the esophagus?

• Yes, the Dx–pH Probe can record liquid pH in the esophagus as well as aerosolized pH in the oropharynx.  The placement of the Probe in the oropharynx, posterior to the uvula, seems to be the most comfortable location for children and the clinical results from this location accurately display laryngopharyngeal pH levels attributable to gastric reflux events. Positioning the Probe in the lower pharyngeal area is possible, although not recommended because of possible patient discomfort.

How does the Dx–pH Probe stay in place?

• After the probe is positioned, it is secured using Tegaderm™ tape as close to the nose as possible.  This will ensure that the probe does not slip out of place.  The catheter is constructed with a pliable plastic material that naturally wants to straighten out after curving through the nasal cavity. This helps keep the sensor pointing downward for optimum pH measurement.

Does the Dx-pH Measurement System measure aerosolized pH, liquid pH, or both?

• The Dx–pH Probe was designed specifically for the purpose of measuring the pH of aerosolized reflux.  It is extremely sensitive and can obtain readings from very little reflux action. The Dx–pH Probe does, in fact, work in a liquid environment, but because of its position above the upper esophageal sphincter (UES), its contact with refluxate is limited mainly to aerosol.  This is because the UES acts as a final barrier to protect the delicate laryngeal tissue from acid exposure.  Impedance technology has revealed that it is extremely rare to get a liquid event above the UES, and that nearly all events in this location are gaseous.

Who is the manufacturer of the Dx-pH Probe System?

• Restech (www.restech-corp.com) is a world leader in engineering medical technologies that provide comfortable, reliable solutions to assist physicians in the diagnosis of reflux-related health problems quickly and reliably.  The engineering team at Restech is led by professionals with over two decades experience in medical device development and hold over 30 patents in the areas of sensor technology, data recording and monitoring systems, and other medical devices.

How does the Dx–pH Measurement System work?

• The Dx–pH Measurement System is a simple tool for 24 to 48 hour ambulatory oropharyngeal pH testing.  Guided by a blinking light-emitting diode (LED) in the probe tip, the physician visually positions the probe just behind the soft palate.  Once placed, the single-channel Dx–pH Probe takes a pH reading every 1⁄2 second then sends the data wirelessly from the attached Dx–Transmitter to the Dx–Recorder.  Throughout the study, the parent inputs clinically relevant information (e.g. meals, symptoms) with the push of a button.  Upon completion of the study, the pH data and patient information is downloaded from the SD memory card into the Dx–pH DataView software program to be viewed, graphed and printed.