Objective: To compare pulse oximetry saturation (SpO(2)) with arterial bloo
d gas saturation (SaO(2)) obtained during clinical routine to determine the
optimal lowest reliable value of SpO(2) in ventilator-dependent patients b
efore setting up a nurse-directed protocol of FIO2 titration.
Design: Prospective clinical study.
Setting: Surgical intensive care unit in a university hospital.
Patients: Thirty-three patients with a pulse oximeter probe in whom arteria
l blood gas was measured with a radial artery line.
Interventions: SpO(2) was recorded by the nurses and compared with SaO(2) o
btained by blood gas analysis with a co-oximeter. Two sensors currently use
d in our surgical intensive care unit and connected to a monitor (HP OmniCa
re M1165/66A; Hewett Packard, Andover, MA) were tested. In group I, the Dur
ensor DS 100A (Nellcor Puritan Bennett, Pleasanton, CA), a reusable sensor,
was used. In group II, the Oxisensor D25L (Nellcor Puritan Bennett), a non
reusable sensor, was used.
Measurements and Main Results: In group I, 64 data pairs were obtained. In
this group, SaO(2) ranged from 87 to 98% and SpO(2) ranged from 92 to 100%,
The bias was -1.90% and the limits of agreement ranged from -5.56 to 1.76%
. In group 11, 47 data pairs were obtained. In this group, SaO(2) ranged fr
om 87 to 99% and SpO(2) ranged from 92 to 100%. The bias was -2.49% and the
limits of agreement ranged from -6.62 to 1.64%.
Conclusions: In the range of SaO(2) tested, regardless of the sensor used,
SpO(2) overestimated SaO(2). Large limits of agreement were found. Based on
this result, the authors concluded that before defining a nurse-directed p
rotocol of FIO2 titration with SpO(2), the material used daily must be eval
uated. A minimum threshold SpO(2) value of 96% in both groups I and II is m
ore reliable to ensure SaO(2) greater than or equal to 90%.