Transcutaneous Oximetry during Hyperbaric Oxygen Therapy

Overview

Hyperbaric oxygen therapy (HBO2 ) is recommended in different conditions associated with the necessity to increase the oxygenlevel in affected tissue. The principle of treatment is to increase the oxygen supply to ischaemic tissue by supplying oxygendissolved in blood during increased surrounding pressure. Transcutaneous measurement of partial oxygen pressure (PtcO2 ) is usedfor indications of ischaemic affections for hyperbaric oxygen therapy.HBO2 was applied at a pressure of 0.28 MPA for a period of 80 mins. Values of PtcO2 under these conditions were notpublished so far. The authors investigated PtcO2 values in 29 patients with ischaemic disorders of the lower extremities, placing theelectrode on the tarsus of the foot and on the external side of the crus. The control group comprised 127 patients, treated withHBO2 on account of other diseases. For statistical comparison the double-selection t-test with unequal scatter was used.The PtcO2 values on the healthy tarsus increased during HBO2 roughly eight times (from ca 60 to 480 mmHg). On the affectedextremity roughly five times (from ca 60 to 300 mmHg). The differences of the two groups were statistically significant (p < 0.01 -⁠ 0.05).On the healthy crus there was a roughly ninefold increase of pO2 (from 65 to 600 mmHg) and on the affected crus a sixfoldincrease from 60 to 360 mmHg). The difference of these groups was statistically significant (as a rule p < 0.001).The assessed values of PtcO2 could be only approximately compared with the results of other authors. Assessment of PtcO2during HBO2 can be considered in ischaemic affections of the lower extremities a possible objective evaluation of the direct effectof therapy on the affected extremity. To assess the exact borderline (e.g. achievement of a minimum of 100 mmHg) when HBO2 ispurposeful or when it should not be started is very difficult. In all instances not only repeated measurements are needed but alsoassociation with subjective conditions of patients and visual evaluation of the wound.In future transcutaneous measurement of the partial oxygen pressure of the lower extremities during hyperbaric oxygen therapywill be used as an orientational objective method for evaluation of the perspective of treatment of ischaemic affections.

Key words:
hyperbaric oxygen therapy, transcutaneous oximetry, limb ischaemia