Iowa Oral Performance Instrument (IOPI)
User Manual
Model 2.1
January 2008
WARNINGS!!
The tongue bulbs, as supplied by IOPI Northwest LLC, are NOT STERILE.
DO NOT put the tongue bulb in the mouth of a person if there is a significant risk of them having a seizure.
DO NOT use the tongue or hand bulb with a person who has any current or past problem with pain disorders involving the muscles or joint of the mandible ("TMJ Disorder," "Myofacial Pain Disorder") or of the wrist (Carpal Tunnel Syndrome).
HOLD ON to the tongue bulb tube any time it is in a person’s mouth.
The tongue bulb and hand bulb supplied with the IOPI are designed to measure the strength and fatigability of the tongue and hand, respectively.They should never be used for any other purpose.
The user should warn any person who is to perform the tongue fatigue measurement at or higher than 50% of their maximum tongue strength that they may experience some "throat" soreness following the measurement. This condition may persist for as long as 24 hours.
Parts of the IOPI
| A. Tongue bulb:
Squeezed by the tongue to measure tongue strength and fatigability. B. Connecting tube: Connects the tongue bulb tube to the Pressure Port. C. Data Out Port: Provides a continuous voltage representing bulb pressure. D. Pressure Port: Short stainless steel tube that connects to female end of Connecting Tube. E. Hand bulb: Squeezed by the hand to measure hand strength and fatigability. |
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IOPI Control Buttons
| Light [On/Off]: "On" allows
the relative pressure to turn on the appropriate light in the column of
lights, and the LCD display shows the value of "Set Max." In the "Off"
condition, no light will ever be turned on Set Max: Up arrowhead increases the maximum pressure needed to turn on the top light in the column of lights. Down arrowhead decreases this pressure Timer: Displays the elapsed time. Start: Starts the timer counting in seconds. Stop: Stops the timer from counting. Reset: Resets the timer to zero. Peak: Displays the maximum pressure achieved during a response. Reset: Set the peak-finding function back to zero, assuming there is no pressure at the pressure port. Power [On/Off]: Turns battery power on and off. IOPI will turn itself off after 15 minutes without a button push or pressure response. |
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How does the IOPI measure strength?
The IOPI measures the maximum pressure a person can produce in a standard tongue bulb by pressing the bulb against the roof of their mouth with their tongue "as hard as you can." This maximum pressure is a measure of strength. The strength of the hand is measured by the maximum pressure an individual can produce by squeezing a small rubber bulb. The unit of the pressure is the kiloPascals (kPa). The relative size of a response, compared to a person's maximum pressure, can be displayed on a column of lights (LED's).
How does the IOPI measure fatigability?
The IOPI measures how fatigable a person is by finding out the length of time that a patient can maintain 50% of their maximum pressure.
IOPI Accessories
Tongue bulbs
Tongue bulbs are used to measure the strength and fatigability of the tongue by having the patient squeeze the blue bulb against the hard palate (roof of the mouth) just behind the alveolar ridge. These bulbs come in a sealed package. They are clean* but they are not sterile. The user may have a hospital sterilize the bulbs in their package by using cold gas (EO—ethylene oxide).
Tongue bulbs come with a nylon plug in the end of the tube. It keeps the bulb from flattening and/or becoming dimpled during long periods of storage in the sterilization pouch. The plug may be removed with pliers or cut off the end of the tube with a pair of scissors.
Hand Bulb
The Hand Bulb is an optional accessory. It is used to measure the strength and fatigability of the hand by having the patient squeeze the bulb. The correct hand position is illustrated below. To use the bulb, just slip the metal tube on the free end of the connecting tube (see below) into the tube on the hand bulb. The bulb may be washed with dish or hand soap, but don’t allow water to enter the tube on the hand bulb. The hand bulb should be sealed in an air-tight bag when not in use.
Connecting Tube
One connecting tube comes with each IOPI. The end with the metal tube is to be inserted into the tube on the tongue or hand bulb. Insert only 2-3 mm of the exposed part of the metal tube in order to provide an air seal (see Appendix for rationale). The opposite end of the connecting tube slips over the pressure port on the IOPI. Slip the connecting tube coupler over the pressure port as far as it will go.
The connecting tube can be damaged by exposure to strong sunlight or chemicals. Store this tube, when not in use, out of the sunlight in a sealed air-tight bag.
30cc syringe
A 30cc syringe is included with each IOPI. It is used to check the calibration of the IOPI. See "Checking Calibration" in the Maintenance section.
Recommended Testing Procedure
Note: The following procedure assumes the User has purchased the optional IOPI Hand Bulb. If the Hand Bulb has not been purchased, those parts of the procedure referring to hand strength or fatigability may be ignored.
Setup
The patient should be close enough to the IOPI to have slack in the connecting tube. During the test of fatigability, they will need to see the column of lights on the IOPI.
Start with the hand strength measures because most people seem to understand the task better with the hand bulb than the tongue bulb. The following order of tests is suggested to minimize the effects of fatigue.
1. Hand strength
2. Tongue strength
3. Hand fatigue test
4. Tongue fatigue test
Attach the connecting tube to the IOPI, push the "Peak" button and then press the Peak "Reset" button. The LCD display should read "0".
Procedure
Hand strength
Place the handbulb in the person’s preferred hand, making sure the fingers are wrapped around the bulb, without the fingertips digging into the bulb (see drawing below). Ask the patient to "squeeze the bulb as HARD as you can for about 2 seconds." Verbal encouragement during this request is acceptable, and helps some people. The 2 second hold is not important; it just avoids the question "How long should I hold it?" when you tell them to squeeze the bulb.
After the patient has made their maximum response and relaxed, record the value on the IOPI LCD display, and then push the Peak "Reset" button. Let the patient rest for 30 seconds to a minute, and have them repeat the measurement a second and third time. The maximum hand strength is the highest of these three numbers. If values consistently decrease over the three trials, the rest period may not be long enough.
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Midsagittal view of the human face, illustrating the standard position of the tongue bulb in the mouth |
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Correct (A) and incorrect (B) positions of the fingers when squeezing the hand bulb. Digging the fingertips into the bulb (B) may produce readings that are too high. |
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Tongue strength
Attach the connecting tube to a tongue bulb. Follow the procedure previously described for hand strength testing. Hold on to the stem of the tongue bulb (the 3 mm tube) while it is in the patient’s mouth. Position the bulb against the hard palate and tell the subject to press the bulb with their tongue "as HARD as you can for about 2 seconds." The 2 second hold is not important; it just avoids the question "How long should I hold it?" when you tell them to squeeze the bulb.
Hand fatigue test
Place the IOPI so the column of lights can be easily seen by the patient. Attach the hand bulb to the connecting tube. Press the "Lights" button to enable the column of lights. The bottom light will turn on, indicating that the lights are enabled. Push the Timer "Stop" button, and then push the Timer "Reset" button. Use the "Set Max" buttons to make the LCD show the value of this patient’s maximum hand strength reading. Ask the patient to squeeze the hand bulb, using the standard finger position, until the middle (green) light comes on, and keep it on "for as long as possible." Just as soon as the green light comes on, press the Timer "Start" button. It is OK if the lower or upper yellow light comes on briefly. If, however, the lower yellow light comes on for over a second, remind the patient to squeeze hard enough to keep the green light on. It is acceptable to encourage the patient "to keep going as long as possible". If the patient cannot make the green light come back on in about 2 seconds, then press the Timer "stop" button, and then tell the patient to relax. It is more common, however, that the patient "gives up" suddenly. Stop the timer immediately if this happens. Most people show signs of "struggle" toward the end.
Press the "Timer" button. The LCD display will show the time, in seconds, that the patient maintained a pressure of 50% of their maximum hand strength. Record this number. Do this test only once with each patient.
If the "Timer" button is pressed after the Set Max value is adjusted, the IOPI will display the elapsed time during the fatigue trial. Because earlier models of the IOPI could not be set in this manner, the effect of allowing the subject to see their elapsed time is not known.
Tongue fatigue test
This test is similar to the hand fatigue test (above), except that the patient uses the tongue to squeeze the tongue bulb to achieve 50% of their maximum tongue pressure reading. The time that people are able to hold 50% of their maximum with the tongue is usually less than it is when they are using the hand.
IOPI Maintenance
Batteries
The IOPI has one 9 volt replaceable battery. When the voltage of the battery is low, the symbol "Lo Bat" will show in the upper left corner of the LCD display. When this symbol is seen, the battery should be replaced.
Calibration Check
To check the zero balance and gain calibration, turn on the power to the IOPI, but do not push any other buttons. In this "start up" condition the IOPI continuously displays the pressure sensed at the Pressure Port.
Zero Balance Check
The display should show, without anything connected to its Pressure Port, a value of "0". This calibration condition is set by IOPI Northwest LLC when the IOPI is at normal room temperature, i.e. 68ºF-70ºF (20ºC-21º C). Pressure sensors are always, to some degree, sensitive to large variations of temperature, so the IOPI may exhibit small positive or negative numbers at temperatures significantly warmer or colder than room temperature.
Gain Calibration Check
Turn on the IOPI. Set the front edge of the plunger of the syringe on the front edge of the 30cc mark. Leaving the plunger in this position, connect the metal tube on the connecting tube to the syringe. Slowly depress the plunger so that the front edge of the plunger lines up with the front edge of the 15 cc mark. Hold this plunger position for 5-10 seconds. The numbers on the display may go down a little. Note the reading when the numbers don’t change anymore.
The number that will be shown during this check depends on your altitude above sea level. Determine the altitude of your location above sea level, and consult the graph below to find out what reading you should see. If you repeat this test several times, and your readings are off by more than 2 kPa, contact IOPI Northwest LLC.
Relationship between altitude with respect to sea level and the pressure created by reducing a volume of air by 100% (30cc reduced to 15 cc).
Technical Notes Concerning the Data Out Port
The Data Out port is designed for a 3.5mm mono plug. It is very easy for an electronic shop to make a cable to your specification, but if no electronics shop is available to you, IOPI Northwest LLC can make a cable to your specifications.
The Data Out signal should not be applied to any input whose resistance is less than 1K ohms. The Data Out signal should be within 1-2 mv of zero volts at zero pressure. The gain of the signal is about 19-20 mv/kPa; the exact gain, however, should be determined by the user.
Troubleshooting
Air leaks
Leaks of air from anywhere, in the bulb, connecting tube, or inside the IOPI, will usually be obvious because the tongue bulb will be flattened or dimpled after it has been squeezed vigorously for a several seconds. Another symptom would be abnormally short periods of time that a person can maintain 50% of their maximum. Air leaks, if they occur, can produce large inaccuracies of the measurements, and thus need to be detected and eliminated. The possible causes of an air leak are:
1. The tongue bulb leaks. Try another tongue bulb.
2. The handbulb is faulty. Place the entire hand bulb, and its connection to the connecting tube, under water. Apply a squeeze to the bulb, and look for bubbles escaping.
3. There is a leak where the connecting tube connects to the pressure port. Put some soap bubbles around the seam between the pressure port and the plastic collar. Apply a squeeze and look for soap bubbles that get larger or move around.
4. There is a leak inside the IOPI. This is unlikely, but if the other three possibilities are eliminated, then a leak inside the IOPI could be the cause. Contact IOPI Northwest LLC as soon as possible.
IOPI Normative Database, Linear Regression Model: 95 % confidence limits
Donald A. Robin and Erich S. Luschei (1992), University of Iowa, Iowa City Iowa
See Normal Values page of this website
Appendix
After being assembled, the tongue bulbs are carefully washed in warm water with dishwashing detergent. After being thoroughly rinsed, they are blotted with a freshly washed lint-free cloth and then air dried. They are then placed in sterilization pouches using clean tongs to touch the bulb. The bulb and the first 2 inches of the tube beyond the bulb are not touched by the hands during the packaging.
Inserting the metal tube too far makes it difficult to remove a used tongue bulb. The force necessary to remove it may then pull the metal tube out of the end of the connecting tube.