An in vitro quantification of pressures exerted by earlobe pulse oximeter probes following reports of device-related pressure ulcers in ICU patients .

The earlobe often is used to monitor perfusion when pulse oximeter signal quality is impaired in the fingers and toes. Prompted by intermittent occurrences of roughly circular earlobe pressure ulcers among patients in intensive care units, a convenience sample of seven calibrated pulse oximeter probes was used to quantify earlobe pressure exerted by these devices in vitro. All were tested twice with an electronic load cell, a strain gauge with a transducer that transforms the measured force into a readable numerical signal. The probe was clipped to the load cell just as it is clipped to the earlobe in the clinical setting. The probes exerted an average of 0.24 lb (SD 0.6) of force over an area of 0.3 square inches, equal to an average of 20.7 mm Hg (SD 0.6) pressure on tissue. This value exceeds some empirically derived values of capillary perfusion pressure. The occurrence of device-related pressure ulcers, as well pressure ulcers on the ears, has been documented, but little is known about device-related earlobe pressure ulcers or the actual pressure exerted by these devices. Additional in vitro studies are needed to quantify the pressures exerted by these and other probes, and future prevalence and incidence studies should include more detailed pressure ulcer location and device use documentation. Until more is known about the possible role of these devices in the development of pressure ulcers, clinicians should be cognizant of their potential for causing pressure ulcers, particularly in patients whose conditions can compromise skin integrity.