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Iowa Neonatology Handbook: Pulmonary
Transcutaneous Oxygen (TcPO2) Monitors
Jonathan M. Klein, MD
Peer Review Status: Internally Peer Reviewed
I. The transcutaneous PO2 monitor (TCM allows for
non-invasive measurement of arterial oxygen tension. The prerequisite
for accurate correlation of an arterial PO2 value with a
transcutaneous PO2 value is creation of constant local vasodilatation
by heating the skin. This causes maximal blood flow in the skin with
little or no difference between the PO2 value at the arterial and
venous ends of the capillary.
II. The transcutaneous PO2 monitor consists of a combined platinum
and silver electrode covered by an oxygen-permeable hydrophobic
membrane, with a reservoir of phosphate buffer and potassium chloride
trapped inside the electrode. A small heating element is located
inside the silver anode. The oxygen monitor consists of a TcPO2
channel, for which high and low alarm limits can be set, a
temperature display channel and a heat channel.
III. The TCM sensor is applied by the nurse to the anterior chest
wall or other acceptable site and heated to 44°C. The site will
be changed every four hours to avoid erythema and burns to the
infant's skin. The electrode will be calibrated by the blood gas
technician and recalibrated every eight hours.
IV. The nurse will record the TCM value on the nurse's notes at
least once an hour. When correlating the transcutaneous PO2 with an
arterial or capillary blood gas sample, the value from the TCM should
be recorded 15 seconds after obtaining the blood sample.
V. An order should be written documenting the desired range of
transcutaneous oxygen levels for a given patient. The optimal range
for most premature infants will be 50 to 70 mm Hg. Higher limits may
be appropriate for large preterm or term infants, especially those at
risk of pulmonary hypertension.
VI. If the patient's transcutaneous PO2 stays outside of these
limits for more than two to three minutes, the nurse shall increase
or decrease the FiO2 by no more than 0.05 until the patient's reading
returns to the desired range.
VII. If a change in FiO2 is required for more than five minutes,
the House Officer shall be notified of the change in the infant's
condition. The change in FiO2 and response of the infant will be
documented in the nurse's notes.
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