Use of Nurse Call Pendants and Pillow Speakers by Patients Receiving Oxygen Therapy
User Experience Network™ [Health Devices Dec 1996;25(12):477-9]
Our nurse call pendants and pillow speakers bear a notice stating that
they are not to be used in locations where oxygen is being administered. We understand
that other institutions are permitting patients who are receiving oxygen to use these
controls. What should we do?
An oxygen-enriched atmosphere (OEA) is an atmosphere in which the
concentration of oxygen exceeds 23.5% by volume. A high-concentration OEA (often
approaching 100% oxygen) normally exists in an oxygen tent, croup tent, incubator, oxygen
hood, or similar device. In such locations, the use of nurse call pendants and pillow
speakers may be a concern. However, these devices are most likely to be used in
lower-concentration OEAs—specifically, in or near the "site of intentional
expulsion" (SIE) of oxygen from an oxygen-administration device such as a nasal
cannula or a face mask. NFPA 99-1996 defines an SIE as "all points within 1 ft (0.3
m) of a point at which an oxygen-enriched atmosphere is intentionally vented to the
atmosphere" (Section 2.2).
We believe that the fire risk posed by nurse call pendants and pillow
speakers (and other low-voltage control pendants) is very low in the most common
applications, even if the pendant is brought within the 1 ft zone of an SIE. This is
because of the low voltages and currents in the controls, the typically low probability of
there being any ignitable fuels in components that are subject to arcing or sparking, and
the lack of hot components in these devices. Moreover, although many institutions are
presumably using pendants not listed for oxygen use, we are aware of no reports of
Some of the confusion surrounding this issue
may arise from NFPA's recommendations on the subject. Section 7-220.127.116.11 of NFPA 99 states: "Electrical
equipment used within oxygen delivery equipment shall be listed for use in oxygen-enriched
atmospheres, or sold with the intent to be used in oxygen-enriched atmospheres."
However, the 1996 edition of NFPA 99 has added a section (A-7-18.104.22.168) to its appendix
stating that "the intent of 7-22.214.171.124 is to advise users to specify appliances that
meet higher requirements where the hazard is higher, but not to overspecify where the
hazard is minimal. Thus, as they are ordinarily used, nurse call buttons, pillow speakers,
etc., do not need to be listed for use in oxygen-enriched atmospheres." In other
words, when used in SIEs (not in high-concentration OEAs), these devices need not be
listed for use in an OEA.
The appendix material does caution, however, that "these requirements
apply only to the intended use. The user must exercise vigilance to guard against an
unintended use or an accidental failure, which can vastly increase the hazard." In
our opinion, NFPA 99-1996 does not intend the use of nurse call buttons or pillow speakers
in areas of especially high oxygen concentration (e.g., approaching 100%), such as would
be found in oxygen tents or hoods.
- Do not permit the use of nurse call or pillow
speaker pendants in enclosed spaces having a very high concentration of
oxygen, such as oxygen tents or hoods, unless the pendants are labeled for
use in an OEA.
- Permit the use of nurse call and pillow speaker
pendants in low-concentration OEAs, such as the SIE around patients
receiving oxygen by nasal cannula or face mask.
- If you encounter applications for which you feel additional precautions
are needed (for example, using speakers and pendants in areas with reduced
ventilation), consider one or more of the following measures:
- A series of curves (Figures 9-126.96.36.199[a] through
[f]) published in NFPA 99-1996 provides safe-design criteria for
circuits used in OEAs. Your clinical engineering personnel may be able
to determine, with the help of information from the manufacturer of your
system, whether voltages and currents to which the pendants are exposed
remain within the safe regions defined by these curves.
- Tether the pendant to an object near the bed.
The tethering should not be easily defeated by the patient, but should
keep the pendant within the patient's reach. Properly tethered, the
device will be prevented from being brought in so close that the patient
might, for example, fall asleep with it near the mask or cannula.
Alternatively, the pendant can be bracketed to the bedrail instead of
- Replace the usual control with one that is
pneumatically connected (e.g., using a squeeze bulb and tubing) with
switches or other electrical control devices attached to the system wall
- Determine whether the original manufacturer has specialty pendants or
accessories that are approved for use in an OEA.
- Nurse Call Systems [15-614]
- Pillow Speakers [17-198]
Cause of Device-Related Incident
External factor: Medical gas and vacuum supplies
Mechanism of Injury or Death