Cellular telephones; irrigation fluid; insufflation filters; sterilization condensate; counts; head covers - Statistical Data Included

AORN Journal, July, 2000 by Ramona Conner

Question: I have been asked to research the issue of cellular telephone use in the OR. I believe our policy was written when cellular telephones were first marketed and does not apply to the digital telephones that now ore available. People in my facility believe the telephones will interfere with ventilators or electrosurgical units. Does AORN have any suggestions regarding this issue, or are you aware of any relevant research that has been conducted?

Answer: All cellular telephones, whether digital or analog, generate electromagnetic fields and may cause electromagnetic interference (EMI) of various medical devices, especially at close range.(1) The OR should prohibit the use of cellular telephones by patients, visitors, and staff members (including physicians). Cellular telephones carried into the area should be turned off because they will intermittently transmit network signals when in the "on" mode.

For a cellular telephone to cause a medical device such as monitoring equipment, electrosurgical units, or pacemakers to malfunction, either

* the cellular telephone must generate electromagnetic fields with the right combination of waveform characteristics powerful enough to corrupt the electronic signal, or

* the frequency of fields generated must match a frequency used by the, medical device, allowing the cellular telephone to override the intended signal.

Medical device malfunctions occur if the device interprets corruption of its electronic signals as actual data or as computer instructions. The effect on the medical device may go undetected, and the malfunction may be unpredictable. For example, the anesthesia monitor may improperly adjust preset settings, improperly sound an alarm, fail to sound an alarm, or stop without warning.

Cellular telephones that operate at low frequency (ie, 900 MHz or less) are more likely to cause interference that those that operate at higher frequency (ie, 1,800 MHz). Low frequency telephones are three times more likely to interfere with medical devices than higher frequency telephones. In the United States, cellular telephones operate at frequencies in the range of 800 to 900 MHz and higher.(2)

Distance also affects the likelihood of interference. Most interference occurs when the telephone is within 1.6 ft (ie, 50 cm) of the device. According to ECRI, when cellular telephones are used at distances greater than 3 ft from medical devices, the risk of interference and of jeopardizing patient safety is minimal.(3) Even if the risk of interference, is small, it should not be ignored.

Medical device manufacturers are beginning to design equipment and devices that are less susceptible to EMI. New devices may be shielded from interference, and error detection and error correction logic may be incorporated in the design to minimize the effects of data corruption caused by interference. When purchasing new equipment, require the manufacturer to provide information regarding the EMI susceptibility of the device. Although new designs may reduce the risk of interference, most facilities still use devices that were not designed to resist EMI.

Health care facilities should continue to restrict the use of cellular telephones in certain areas where sensitive electromedical devices are in use. Experts recommend that cellular telephones be prohibited in ORs, postanesthesia care units, critical care units, emergency rooms, diagnostic imaging areas, and clinical laboratories. It is no longer considered necessary, however, to ban the use of cellular telephones throughout the facility.(4)

Question: For surgical hysteroscopies, what is the recommended irrigation fluid when using electrosurgery?

Answer: Despite concerns about the use of conductive irrigation solutions with electrosurgical devices, saline is the most common irrigant used. The passage of electrical current through a conductive irrigant such as saline disperses the current over a wide area. Although the current is then being delivered to untargeted tissue, hazards are minimized because the current is dispersed over a large area. This also has the effect of diminishing the surgical effectiveness of the electrosurgical device, thus requiring an increase in the power from the electrosurgical unit to restore the surgical effect. If this problem is significant, one of the more expensive nonconductive solutions can be used. If a nonconductive irrigant is used, then resistance between electrodes may occur, also necessitating the use of more energy.(5) The choice of irrigant depends on the surgeon's preferences, patient condition, reason for irrigation use, anticipated bleeding, and solution cost.

Question: Are filters recommended on any kind of insufflation tubing? Some manufacturers are recommending that filters be used for all insufflation procedures (ie, on the tubing lines). Is there any standard or recommendation from AORN regarding this?

Answer: The "Recommended practices for endoscopic minimally invasive surgery" state

   Insufflator equipment should include a single-use hydrophobic filter that
   is compatible with the insufflator and impervious to fluid.(6)