Transcutaneous Blood Gas Monitoring A Multi-Disciplinary Clinical Competency

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Transcutaneous Blood Gas Monitoring A
Multi-Disciplinary Clinical Competency

• New England Medical Center
• Respiratory Care Programs

Rev 1 03-01-01
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Transcutaneous Monitoring Target Population

• Neonates, infants, and small children
• Transcutaneous monitoring measures skin-surface
  PO2 and PCO2
• Estimates arterial partial pressure of oxygen and
  carbon dioxide (PaO2 and PaCO2)
• Induces hyperperfusion by local heating of the
  skin
• Measures partial pressure of oxygen and carbon
  dioxide electrochemically

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Transcutaneous Monitoring Target Population

• Neonates, infants, and small children
• Measures partial pressure of oxygen and carbon
  dioxide electrochemically

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Transcutaneous Monitoring INDICATIONS

• The need to monitor the adequacy of arterial
  oxygenation and/or ventilation
• The need to quantitate the response to diagnostic
  and therapeutic interventions as evidenced by
  PtcO2 and/or PtcCO2 values

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Transcutaneous Monitoring CONTRAINDICATIONS

• Poor skin integrity
• Adhesive allergy

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TCM Monitoring HAZARDS/COMPLICATIONS

• False-negative and false-positive results may
  lead to inappropriate treatment of the patient
• It is appropriate to correlate non-invasive
  values with arterialized blood values
• Tissue injury may occur at the measuring site

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TCM DEVICE LIMITATIONS/VALIDATION OF RESULTS

• TCM monitoring is an indirect measurement
• Does not reflect oxygen delivery or oxygen
  content.
• Complete assessment of oxygen delivery requires
  knowledge of hemoglobin, saturation, and cardiac
  output
• PtcCO2 accuracy is proportional to several
  factors
• Site placement
• Probe temperature
• Perfusion
• Body temperature

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TCM DEVICE LIMITATIONS/VALIDATION OF RESULTS

• TCM monitoring is an indirect measurement
• The following factors may increase the
  discrepancy between arterial and transcutaneous
  values--
• hyperoxemia (PaO2 gt 100 torr)
• a hypoperfused state (shock, acidosis)
• Improper electrode placement or application
• Vasoactive drugs
• The nature of the patient's skin and subcutaneous
  tissue (skinfold thickness, edema)

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TCM Monitoring Validation

• Arterial blood gas values should be compared to
  transcutaneous readings taken at the time of
  arterial sampling in order to validate the
  transcutaneous values.
• Validation should be performed initially and
  periodically as dictated by the patient's
  clinical state.

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TCM Monitoring Validation

• During validation studies in patients with
  functional shunts, electrode site and arterial
  sampling site should be on the same side of the
  shunt.
• When disparity exists possible causes should be
  explored before results are reported.

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TCM Monitoring Reducing disparity

• Monitoring at alternate sites
• Recalibration
• Re-membrane TCM probe
• Increasing TCM probe temperature
• (Usually obligates clinician to increase site
  change frequency)
• Substitution of instrument

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TCM ASSESSMENT OF NEED

• When direct measurement of arterial blood is not
  available/accessible
• When lab turn-around time is excessive
• PtcO2 and/or PtcCO2 measurements may temporarily
  suffice if the limitations of the data are
  appreciated

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TCM ASSESSMENT OF NEED

• Appropriate for continuous and prolonged
  monitoring (eg, during mechanical ventilation,
  CPAP, and supplemental oxygen administration)
• PtcO2 diagnostic values
• assessment of functional shunts (eg, persistent
  pulmonary hypertension of the newborn, PPHN, or
  persistent fetal circulation
• Useful to determine the response to oxygen
  challenge in the assessment of congenital heart
  disease

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TCM FREQUENCY

• Transcutaneous blood gas monitoring should be
  continuous for development of trending data.
• Spot checks are not appropriate
• Reference Adapted from AARC Clinical Practice
  Guideline
• Transcutaneous Blood Gas Monitoring for Neonatal
  Pediatric Patients Respir Care
  199439(12)1176-1179)