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.
- Leslie A. Geddes
- CRC Press
- ENGR. R856.6 G43 1998
Product Liability and Medical Technology
- 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.
Medical Device Reports
- 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).
The Incident Report
- Report the basic facts about an incident
- Does not assign culpability to anyone
Electromagnetic Interference and Electrostatic Discharge
- 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.
Sources of EMI
- Radio broadcasting
- 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
- 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
Examples of Device Malfunction due to EMI
- 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.
- Power-vehicle mishaps
- Cellular and mobile telephone-generated EMI
- Infant radiant warmer
- Paging system generated EMI
Cardiac Pacemakers and 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
- MRI (magnetic resonance images)
- Low-frequency EMI
- Arc welding machines
Electrostatic Discharge (ESD)
- 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
Some Background (Skipped)
- Anesthesia machine
- In-circuit type and out-of-circuit type
- Circuit refers to patient breathing cycle
- Auxiliary equipment
- Warming blanket, warming cabinet
- Related monitoring equipment
- Anesthesia-machine monitoring
- Patient monitoring
Mishaps with Anesthesia Machine
- Failure in absorbing exhaled carbon-dioxide
- Valve malfunction
- Leaks & disconnections
- 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)
- By defibrillator
- By endotracheal tube
- By laser
Four More Skipped Chapters
- Catheter Accidents
- Direct-Current Injuries
- Transcutaneous Electrical Nerve Stimulation
- Tissue Injury
Experiences That May Help Technical Experts
- Chapter about author’s legal & investigation experience
- Medical device investigation
- Patent infringement and invalidation
Where to find information
- 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
- 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.