Transcutaneous oxygen measurement during thoracic anaesthesia

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Medical Monitoring

Background:

• Monitoring oxygenation is crucial during anesthesia.
• Transcutaneous oxygen tension (tcPO2) offers a non-invasive method for assessing tissue oxygenation.
• Its utility during thoracic anesthesia requires further investigation.

Purpose of the Study:

• To evaluate the value of tcPO2 as an oxygen parameter during uncomplicated thoracic anesthesia.
• To compare tcPO2 measurements with arterial oxygen tension (PaO2) under various inspiratory oxygen fractions (FIO2).
• To assess potential interference of anesthetic agents with tcPO2 readings.

Main Methods:

• Ten patients undergoing thoracic anesthesia with oxygen-nitrous oxide and enflurane or flunitrazepam/fentanyl were studied.
• tcPO2 was measured using a Radiometer TCM-I monitor at 45°C.
• Measurements were compared with simultaneously obtained PaO2 values preoperatively and peroperatively.

Main Results:

• No significant interference from anesthetic agents was observed.
• tcPO2 was consistently lower than PaO2 across all tested FIO2 levels.
• No statistically significant differences were found between PaO2 and tcPO2 at FIO2 of 0.5, 0.4, and 0.3 when comparing peroperative to preoperative values.
• Linear regression revealed a disparity between pre- and peroperative PaO2/tcPO2 ratios, indicating a decreasing ratio with increasing PaO2.

Conclusions:

• tcPO2 cannot fully substitute for PaO2 during thoracic anesthesia.
• Both tcPO2 and PaO2 demonstrated comparable utility as oxygen parameters in this patient group.
• Accurate interpretation of peroperative tcPO2 necessitates a preoperative measurement as a reference point.