Rhinomanometry

Factors Affecting Accuracy

• Avoid coaching the patient to breathe: avoid excitement and rapid breathing. The system automatically detects and measures four (4) respiratory cycles during their natural breathing.
• Nasal breathing vs. Mouth breathing. Be sure the patient breathes through their nose as best they can, and avoid mouth breathing as it will show an erratic tracing over the four quadrants of the graph.
• Leakage around the pressure tube and the mask.
• Patient unable to meet the efficiency of the testing pressure gradient. If this occurs, lower the Pascal reference point. See Measurement Considerations below.
• Time of day and altitude may affect the amount of nasal resistance. It is suggested to test the patient approximately the same time of day during their appointment.
• The patient can press too hard on the anterior tubing that collapses and is obstructed. This will show an almost vertical line on the graph and can be corrected by asking the patient to apply less pressure.
• If the respiratory rate is too high, there will be a tendency to create a large open loop on the graph. This is different than the loop found in an internal nasal valve phenomenon. Have the patient breathe slower as they become familiar with the test.
• Allow the patient to obtain visual feedback by watching the screen and the tracing.

• The recommended fixed reference points in Pascals are as follows:
• Standard anterior
• 150 Pa (adult, sitting position)
• 100 Pa (adult with a smaller frame or craniomorphology (as seen in Southeast Asian population), or a growing adolescent, sitting position)
• 75 Pa (adult, supine position)
• 75 Pa (child, sitting & supine position)
• Standard posterior • 75 Pa
• Broms 200 units
• Posture plays a role in testing. Have the patient sit with their head over their shoulders for the most accurate assessment of a normal test result. Also, test the patient in the natural state to see the impact of their posture in nasal breathing and resistance.
• Please refer to the Scoring Considerations for additional information on nasal cycle, flow, and skeletal growth and how it impacts the testing results.

Anterior / Unilateral Test

1. Have the patient blow their nose.
2. Assess the size of the nostril to the size of the foam insert, and cut approximately 6" (15.24cm) of tubing for the test.
3. Connect the foam insert to the anterior tubing.
4. Gently roll the insert like you would an ear foam prior to inserting into the nose, and then place it into the nostril.
5. Check for a good seal; ask the patient to close off the free side of their nose while blocking the free end of the anterior tube.
6. If no leak, connect the anterior tube to the black pressure tube.
7. Select the side you're testing which will be the open nostril, and select the pressure gradient for testing, which will be 75 - 300 Pa.
8. Place the mask over the nose and mouth above the bridge of the nose and begin your test.
9. Record your mean resistance result and enter into DAFNE Score™ to guide you through the data interpretation.

Posterior / Bilateral Test

1. Have the patient blow their nose.
2. Connect both pressure lines to the mask.
3. Cut and place approximately 3" (7.63cm) of posterior tubing and connect it to the small port inside the mask.
4. Select the pressure gradient for testing, which will be 75 Pa.
5. Place the mask over the nose and mouth above the bridge of the nose and begin your test.
6. Record your mean resistance result and enter into DAFNE Score™ to guide you through the data interpretation.

Notes

• These instructions are particular to the rhinomanometer manufactured by GM Instruments, Ltd, but may be universal for other systems.
• Do not place anterior tubing inside the mask for an anterior test.
• To increase the seal, you may use tape by making a hole and placing the tape between the foam insert and the anterior tubing.
• As a visual guide, refer to the Nasal Patency Algorithms & Screening Tools page for examples of various normal and abnormal tracings.

• A zero (0) measurement or zero (0) recorded respirations indicates either complete obstruction or the inability of the patient to meet the threshold for measurement. In this case, drop your measurement in Pa to the next level: if it's 150 Pa, drop it to 100 Pa, etc. You will also see incomplete or erratic lines on the tracing located in the graph.

• Nasal cycle: Left > Right > 20% = Good Nasal Cycle

• Posture & Body Position: Change > 0.20 Pa/cm³/s from sitting to supine indicates OSA,
• Mean score = 0.18 Pa/cm³/s, Normal change is 0.10 Pa/cm³/s
• It is important to identify the effect mandibular repositioning has on the resistance level, as this can create a problem that is not there. For example, if they measure within the normal limits and then increase with an oral device, this could put pressure on the joints causing TMD or other problems, such as headaches or pain.

• Decongestion with < 35% decrease in resistance = structural cause of nasal obstruction rather than a mucosal cause. Be sure to follow practice guidelines and recommendations by societies suggesting waiting 10 minutes after a decongestant spray is applied before acquiring another test and measurement. Testing before 10 minutes will not give you a statistically significant change in decongestion. The average measurement of decrease in Pa is 0.12 Pa/cm³/s.