Related Experiment Video
Updated: Jul 21, 2026
10:46
A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Reliability of the model MC-311 MDI chronolog
F S Wamboldt1, B G Bender, S L O'Connor
1Department of Medicine and Pediatrics, National Jewish Medical and Research Center, Denver, CO, USA.
The Journal of Allergy and Clinical Immunology
|July 10, 1999
Summary
The MC-311 MDI Chronolog device for monitoring inhaler use is unreliable, frequently underreporting actuations and failing due to software errors and thermistor damage. It is not recommended for clinical or research settings.
Area of Science:
- Medical Device Technology
- Respiratory Medicine
- Clinical Engineering
Background:
- The Model MC-311 MDI Chronolog is an electronic device designed to monitor patient adherence to metered-dose inhaler (MDI) therapy.
- It records the date, time, and number of MDI canister activations using a thermistor and microprocessor.
Purpose of the Study:
- To evaluate the reliability and accuracy of the MC-311 MDI Chronolog in recording MDI actuations.
- To determine if the device can accurately report the date, time, and quantity of inhaler use.
Main Methods:
- Twenty-four MC-311 Chronolog devices were tested over 8 days, with actuations simulated at 8-hour intervals.
- Battery voltage was monitored, and 12 devices underwent daily mouthpiece washing.
- Device performance was assessed based on recorded actuations and error patterns.
Main Results:
- Only 42% (10 of 24) of devices met acceptable reliability criteria.
- All reliable devices underestimated MDI actuations, with none recording 320 or more actuations.
- Failures included initial erroneous recordings, 'seizure-pattern' errors associated with washing and battery failure, and likely thermistor damage.
Conclusions:
- The MC-311 MDI Chronolog exhibits significant underreporting bias and frequent failures.
- Initialization errors and seizure-pattern failures compromise data integrity.
- The device is not recommended for use in clinical practice or research due to its unreliability.
