Transcutaneous Oxygen and Carbon Dioxide Monitoring in Normal Cats

Summary Feasibility of noninvasive oxygenation and ventilation monitoring using continuous transcutaneous oxygen (PO2-TC) and carbon dioxide (PCO2-TC) measurements was investigated in six healthy adult male cats anesthetized with isoflurane. Concurrent arterial blood gases, inspired oxygen concentration (FIO2), end-tidal carbon dioxide (ETCO2), PO2-TC were recorded during hyperoxia/normocapnia, normoxia/normocapnia, hypoxia/normocapnia, hypocapnia/hyperoxia, and hypercapnia/hyperoxia. Dorsolateral thorax and dorsal pelvis probe sites were evaluated. Probe site did not significantly affect the parameters. During normoxia and hypoxia, mean PO2-TC was insignificantly greater than mean PaO2 (p > 0.154), but during hyperoxia PO2-TC was less than Pao2 (p < 0.002). At each assessment (except hypercapnia for the dorsal pelvis probe site) PCO2- TC was greater than PaCO2. Correlations between PO2-TC and FIO2 (p < 0.05), and PaO2 (p <0.001), and between PCO2-TCand ETCO2 (p < 0.001), and PaCO2 (p < 0.05) were good; however, the measured values of PO2-TC and PCO2-TC were not directly comparable to the measured values of PaO2 and PaCO2, respectively. Clinical utility of transcutaneous monitoring in cats will require development of the appropriate conversion equation for carbon dioxide and modifications for practical application.