Transcutaneous oxygen measurement during one-lung anaesthesia

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Surgical Monitoring

Background:

• One-lung ventilation (OLV) during thoracic surgery causes rapid oxygenation changes.
• Monitoring arterial oxygen tension (PaO2) is crucial but can be invasive.
• Transcutaneous oxygen tension (Ptco2) offers a non-invasive monitoring alternative.

Purpose of the Study:

• To evaluate the utility of continuous transcutaneous oxygen tension (Ptco2) monitoring.
• To assess Ptco2's effectiveness during the dynamic oxygenation shifts of OLV.
• To compare Ptco2 with arterial oxygen tension (PaO2) during thoracic procedures.

Main Methods:

• Ten patients undergoing thoracic surgery with enflurane-N2O anesthesia were studied.
• Measurements included PaO2, Ptco2, cardiac output, and arterial pressure.
• Data were collected during two-lung ventilation (TLV) and one-lung ventilation (OLV).

Main Results:

• Variables remained stable during TLV.
• Mean PaO2 decreased significantly during the initial 10 minutes of OLV.
• Ptco2 showed a slower decrease, correlating well with PaO2 (r = 0.907).
• Ptco2 values were consistently higher than PaO2 during OLV.

Conclusions:

• Continuous Ptco2 monitoring is a valuable tool for assessing oxygenation during OLV.
• Ptco2 can be used when arterial cannulation is not feasible or lab delays occur.
• The elevated Ptco2 index may reflect the in vivo detection system's response time.