Originally Published EMDM May/June 2002
SPECIAL REPORT
General Hospital Devices and Therapeutic Products
TherOx AO System
A mobile, bedside medical device hyperoxygenates blood drawn from a patient's femoral artery and delivers it to oxygen-deprived tissue and organs
The TherOx AO system is a mobile, bedside electromechanical device that delivers hyperoxygenated blood drawn from a patient's femoral artery to oxygen-deprived tissue and organs via an infusion catheter. The blood is oxygenated within a disposable cartridge by combining it with a standard physiologic solution (saline) and hospital-supplied oxygen.
The initial application for the AO system is treatment of heart attack. Treatment is initiated by an interventional cardiologist in a cardiac catheterization laboratory after primary intervention to reestablish blood flow through the coronary artery. The hyperoxygenated blood is delivered directly to the coronary arteries at a rate of 75 ml/min for a period of 90 minutes.
Targeted delivery of hyperbaric oxygen is accomplished by the following innovations. Aqueous oxygen (AO) is prepared on demand from hospital-supplied oxygen and physiologic solution. The base solution contains more than 150 times the amount of oxygen dissolved in a standard IV solution and is bubble-free.
Delivering AO into patient blood without introducing bubbles requires TherOx's proprietary delivery equipment that controls velocity and the material surface properties.
An automated blood-recirculation circuit withdraws 75 ml/min of blood from a patient, channels it through chambers in a sterile cartridge where it is mixed with AO, and returns the hyperbaric blood to the targeted anatomical regions.
A bubble detector, more sensitive than those created for IV pumps, ensures safe delivery of hyperbaric blood under normal atmospheric conditions.
The unit is approved for sale in the European Union. TherOx is also currently enrolling patients in an FDA Phase II randomized trial in the United States for the heart attack application. TherOx, Irvine, CA, USA.
GSI Audioscreener
A battery-operated, handheld hearing-screening instrument automatically and rapidly determines the presence or absence of hearing impairment
A variety of medical personnel with minimal training in hearing screening such as nurses or technicians may use the GSI Audioscreener to screen hearing in newborns, infants, young children, and uncooperative and cognitively impaired adults. More-advanced medical personnel can perform additional diagnostic measures using other device features. The Audioscreener can be used effectively in any medical setting including neonatal well-baby nurseries, neonatal intensive care units, and pediatric outpatient offices, with no need for the special acoustically treated rooms that are found in typical hearing-testing facilities.
A high-speed digital signal processing subsystem is packaged in the same enclosure with the high-gain, high-impedance amplifier required for ABR signal acquisition. Typical ABR signals are well under 1 µV p-p and are masked by normal EEG signals and environmental electrical noise, including power-line frequency noise. A six-layer PCB is used with multiple power supplies and power supply planes to ensure minimum coupling of digital noise and analogue stimulus artifacts into the sensitive analogue circuits. Software design shuts off access to external memory banks during data acquisition, which further reduces digital noise.
The Audioscreener may be used independently of a PC. Neonatal screening may be performed in the nursery without the need for bulky computer equipment, and without having to remove the infant from its bassinette. The device can be configured to provide a simple text-based display or a more complex graphical display to accommodate the needs and skills of screening personnel.
The portability, ease of use, and reduced test times allow minimally trained medical personnel to screen the hearing of all babies at birth. This approach allows diagnosis of hearing impairment at birth instead of at 3 years of age, which has been the typical time for diagnosis in the past. Studies have shown that intervention beginning shortly after birth allows deaf babies to develop language and speech skills nearly equal to those developed by a non-hearing-impaired infant. Everest Biomedical Instruments Co., Chesterfield, MO, USA; Siemens Manufacturing Company, Inc., Freeburg, IL, USA; and Etymotic Research, Elk Grove Village, IL, USA; GSI Viasys Healthcare, Madison, WI, USA.
Welch Allyn Ear Wash System
A system removes impacted earwax from a patient's ear canal by providing irrigation with suction
The Welch Allyn Ear Wash system is used to remove impacted earwax from a patient's ear canal. Its Hydrovac action provides irrigation with suction. The irrigation introduces water into the ear to dislodge the wax, while the suction removes the dislodged particles of wax and wastewater.
There are three main components to the system: a pressure chamber that connects to a faucet, a handle-hose assembly to convey water to and from a patient's ear canal, and a disposable ear tip to collect dislodged earwax. The Ear Wash system can be used safely by doctors, nurses, nurse practitioners, physician assistants, and any healthcare allied professional. The device may be used in any healthcare setting that has an adequate faucet.
A disposable ear tip is placed onto the handle and then inserted into the ear. The provider can then press the actuator on the handle to begin the procedure. Water coming from the pressure chamber is flushed into the ear, then collected in the ear tip and sent through the handle hose and back into the sink. The ear tip has a screen, which will collect dislodged wax. The ear tip is clear so the provider can view the earwax being removed.
Because it uses a faucet, which can have a great deal of pressure variation for a water supply, the system is designed to ensure that the output water pressure is relatively stable over an extremely large input-pressure range. To compensate for the variability, the pressure chamber is constructed with a flow limiter, multiple chambers with air cushions, and two regulating valves to help maintain the constant output pressure. The resulting stream of water cleans the ear at constant, safe pressure. Welch Allyn Inc., Skaneateles Falls, NY, USA.
OxiFirst Foetal Pulse Oximetry System
A pulse oximetry system provides accurate and continuous measurement of foetal oxygenation
Almost a third of all childbirths in the United States are marked by a period of uncertainty in which obstetricians, nurses, midwives, and parents are concerned about the safety of the baby because of an abnormal heart-rate pattern. In about 30% of all labours, the foetal heart-rate pattern becomes abnormal, or "nonreassuring," at some point in time. In these instances, the obstetrical staff is faced with a dilemma. The nonreassuring heart rate could be the result of a dangerous lack of oxygen to the baby or a more innocuous situation, such as the baby falling asleep. However, the foetal heart-rate monitor often fails to distinguish between the two.
The OxiFirst foetal pulse oximetry system provides obstetricians, nurses, and nurse midwives with an accurate and continuous measurement of foetal oxygenation when the foetal heart-rate monitor displays an ambiguous or nonreassuring pattern.
The OxiFirst system employs a single-use sensor that is inserted into the birth canal once the membranes have ruptured and the cervix is dilated past 2 cm. The sensor rests against the foetal cheek, forehead, or temple. As with conventional pulse oximetry, harmless red and infrared light shines into the baby's skin and the reflected light is captured and analyzed. Oxygen saturation is displayed on a monitor screen as a percentage. Directly measuring oxygenation enables clinicians to make more-confident, accurate decisions about the health and well-being of the foetus during labour and delivery. Nellcor, Pleasanton, CA, USA.
Copyright ©2002 European Medical Device Manufacturer
