Note: This post is my reading notes from the book Medical Device Accidents. It is a good source of knowledge for me and the book is easy to read.

Product Liability and Medical Technology

Background

By 1938 in the U.S., it became recognized by the lawmakers that the public needed protection against unscrupulous vendors of a variety of medical products.
In 1938, FDA was given the authority for seizure, injunction, or criminal prosecution with respect to adulterated or misbranded devices.

~100,000 cardiac pacemakers are implanted manually.
Interference of a pacemaker, causing arrhythmia in the ECG of a patient, was due to an electronic device measure his urine.

Three aspects: manufacturing, design, and misrepresentation.
A hazardous situation arises from product defect, misuse, negligence, and design defect.

In 1990, SMDA passed by congress. Effective on May 28, 1992. Amended in 1995.
Mandated the reporting of incidents associated with the medical devices to FDA in the form of MDR.

A separate topic. Information can be found in the Materials Safety Data Sheet (MSDS), the Drug Insert (DI), and the Physician’s Desk Reference (PDR).

Frequency ranges from kHz—GHz.
Affects MD depending on intensity, frequency, and type of modulation.
Affecting an electronic device via many paths
- Battery operated device: easy access if target is not shielded
- Cable or fluid-fill catheter connects the patient, then the catheter-patient path is a antenna.
- Power-line operated: enter via power line.
- Battery operated but battery charged by a charger, then EMI can enter via the power line.

Radio broadcasting
TV
Public safety and land transportation (frequencies allocated to police, fire, and emergency services, taxis, buses, trucks, railroads, etc.)
Cellular telephones and paging services
Amateur radio and citizens bands
Industrial, scientific, and medical
Radar

Using a patient simulator (can be as simple as a resistor)
Various patient models (for EMI testing) has been designed by AAMI and/or others

Silbert et al. Testing of EEG of a four-year-old boy affected by cellphone signals (even no phone rings)
Knutson and Bulkeley. Pacemaker ECG telemetry system made by SpaceLabs Inc. shows “long periods of flat line” due to TV signals
Apnea (temporary breath breaks) monitor produces less accurate results due to perspiration at place of contact on skin, since the device is impedance-based. This can cause problems if patient stops breathing but the heart continues to pump blood with inadequate oxygen.
Silberg 1993. A variety of mishaps with ventilators.
- Ventilator keys lockup due to interference from a guard’s walkie-talkie.
- “Extreme events” including the simultaneous use of multiple equipment lead to power line disturbances, causing a ventilator in cessation of ventilation, inoperative monitoring, display or error messages, or display of unintelligible messages.
- Ventilator stopped cycling and alarmed while used during a flight.
- Etc.
Power-vehicle mishaps
Cellular and mobile telephone-generated EMI
Infant radiant warmer
Paging system generated EMI

Wajsczuk et al. 1969. A demand pacemaker was inhibited when electrosurgical unit was activated
Wise 1971. Both the cutting and coagulating current inhibited a demand pacemaker.
Greene and Meredith 1972. Newer demand pacemakers revert to fixed rate pacing when interference is present.
Bellott et al. 1984. Reprogramming of DDD pacemakers by electrosurgical current possible. Experiments on 140 cases from 5 manufactures.
Abandoned pacemaker lead causes arrhythmias.
Pacemaker malfunction due to
- Cellphones
- MRI (magnetic resonance images)
- Microwave-oven
- Low-frequency EMI
- Arc welding machines

Example: Electrostatic charge released on to an infusion pump case, causing the pump to fail.

Chapter skipped on first reading. Most accidents related to burns and/or unintended cuts.

20 million anesthetic procedures performed annually (~ year 1998)
5000 cases of brain damage associated
Pulse-ox is a great improvement in assessment of adequacy of respiratory function

Anesthesia machine
- In-circuit type and out-of-circuit type
- Circuit refers to patient breathing cycle
Auxiliary equipment
- Ventilator
- Humidifier
- Warming blanket, warming cabinet
- Defibrillator
Related monitoring equipment
- Anesthesia-machine monitoring
- Patient monitoring
- Alarms

Theory on page 136–137
By itself not much hazards, but in the environment it is used there is high oxygen concentration and fire is possible (Comment: it is like a hazard to anesthesia machine rather than pulse-ox)

Chapter about author’s legal & investigation experience
- Medical device investigation
- Patent infringement and invalidation

Medical device accidents
- Attorneys and expert witness always want to know if the accident under investigation is common or rare.
- Medical Device Reports (MDRs) from FDA.
- Gendron (1988). Unexplained Patient Burns. Quest Publishing.
- Shepherd (1992). Shepherd’s System for Medical Device Investigation and Reporting. Quest Publishing.
- Large data base on medical device accidents maintained by Emergency Care Research Institute (ECRI).
- Journal Health Devices by ECRI.
- On anesthesia, Closed Claims Data Base maintained by American Society of Anesthesiologists (ASA).
- Database maintained by Wood Library of Museum of Anesthesiology.
Medical device standards
- FDA
- AAMI/ANSI
- American Society for Testing Materials (ASTM)
- National Fire Protection Association
- The Underwriters Laboratory
- The Electronic Industries Association (EIA)
- Canadian Standards Association (CSA, FDA analog in Canada)
- International Electrotechnical Commission (EIC, FDA analog in Europe)
- Global Engineering Documents
Legal documents
- Lexis-Nexis data base
- WestDoc data base by West Publishing Co.