[The use of a transcutaneous pO2/pCO2 combination electrode during volume therapy in a child in shock]

We report a 1-year-old boy in hemorrhagic shock due to a large subgaleatic hematoma following severe head trauma (blood pressure (BP) 30/15 mmHg; heart rate (HR) 110; Hb 45 g/l; arterial pH 7.16; BE-20 mEq/l). The child was intubated and ventilated; initial FIO2 was 0.9. In an attempt to monitor the cardiovascular system noninvasively a transcutaneous oxygen/carbon dioxide combielectrode was placed on the chest. Initially we observed a large difference between arterial pO2 (paO2 = 166 mmHg) and transcutaneous pO2 (tcpO2 = 7 mmHg) and arterial pCO2 (paCO2 = 16 mmHg) and transcutaneous pCO2 (tcpCO2 = 55 mmHg), reflecting poor skin perfusion and severe tissue acidosis. Under aggressive volume replacement tcpO2 rose along with BP and tcpCO2 returned to near arterial values. Even after stabilization of gross hemodynamic parameters such as HR and BP and despite reductions in FIO2, tcpO2 continued to increase with further volume replacement, reflecting an existing volume deficit.