OxyLite User Manual
Revision 1.1 | May 2015
32
The display reports a numerical fault
Try removing any sensors and power cycling the OxyLite. If the fault
condition remains please contact technical support, reporting the numerical
fault displayed.
Unexpectedly low oxygen readings
Sensors are subjected to strict quality control procedures prior to dispatch.
Generally speaking, unexpectedly low oxygen readings have a
physiological root cause (where used
in vivo
).
For example, the force exerted by the tip of an OxyLite sensor can easily
exceed capillary closing pressure. Low pO
2
readings will result if this is the
case. To overcome this situation, support the sensor cable and sensor tip
area as neutrally as possible in such a way that the sensor is not exerting
forward or lateral forces on the tissue. Withdrawing the sensor slightly, so
that the tip is not at the end of the track created during placement, can
reduce the pressure on the tissue.
Sensor placement is also commonly accompanied by a short-lived trauma
response. Resultant vasoconstriction may generate low pO
2
readings for
several minutes dependent on the tissue being examined. It is advisable to
wait until the tissue has adjusted to the trauma and a steady pO
2
reading is
obtained.
Another possible source for unexpectedly low oxygen measurements is
inappropriate temperature compensation (refer to section 3.9 above). If the
compensated temperature is greater than the actual temperature at the
measurement site then the reported oxygen reading will be less than the
true pO
2
.
Unexpectedly high oxygen measurement
Sensors are subjected to strict quality control procedures prior to dispatch.
Generally speaking, unexpectedly high oxygen readings have a
physiological root cause (where used
in vivo
).
If a sensor is positioned very near the surface of a tissue, without sufficient
tissue surrounding it to generate an effective seal, atmospheric oxygen may
track along the sensor to the measurement area, resulting in high pO
2
readings. A better oxygen seal can be achieved by using a ‘purse stitch’
around the point of introduction or by positioning the sensor a little further
into the tissue.
When a sensor is partially withdrawn from tissue or adjusted, the insertion
point may open briefly allowing atmospheric oxygen to track to the
measurement site. This may cause a transient in oxygen readings. Once
the tissue re-closes around the sensor, the surplus oxygen will be
consumed and normal readings will resume thereafter.