What is an IOPI?
The Iowa Oral Performance Instrument (IOPI) is a hand-held, portable, battery-powered instrument that can accurately measure tongue strength or hand strength and the relative fatigability of these structures. These measures may be very useful for the diagnosis and therapeutic purposes for professionals involved in the treatment and study of speech and swallowing disorders, and /or those interested in assessing general body strength as represented by the hand grip.
How does the IOPI measure strength?
The IOPI measures the strength of the tongue by measuring the maximum pressure that an individual can produce in a standard-sized tongue bulb by pressing the bulb against the roof of their mouth with their tongue "as hard as you can." The strength of the hand is measured by the maximum pressure an individual can produce by squeezing a small rubber bulb.
The peak pressure produced is displayed on a large, easy to read, LCD. The units displayed are kiloPascals(kPa), using the internationally recognized unit of pressure, the Pascal.
Tongue Bulb (blue) is 3.5 cm long
Hand Bulb (red) is 5 cm long
How does the IOPI measure fatigability?
The relative size of a response, compared to a person's maximum, can be displayed on an array of light-emitting diodes (LED's). For example, if the clinician sets the person's maximum, using the "Set Max buttons, then a person would have to produce 50% of their maximum strength to make the middle (green) light go on. This display can be used as feedback to have the patient produce any fraction of the tongue or hand strength that is desired by the clinician.
To measure a person's fatigability, the clinician just times, using a digital clock inside the IOPI, how long a person can maintain 50% of their maximum response. All the person has to do is watch the IOPI and keep the green light on "as long as you can." Most clinicians (or patients) can easily recognize a state of being fatigable; the IOPI measure, however, provides objective evidence and also a measure of the degree of the problem.