The influence of active warming on signal quality of pulse oximetry in prehospital trauma care

Victims of trauma such as contusions and simple fractures are usually transported by paramedics. Because many victims are intoxicated with alcohol or other drugs, they are vulnerable to some risk of inadequate respiration. Thus, their oxygenation is monitored by noninvasive pulse oximetry. We tested the hypothesis that active warming of the whole body during transport to the hospital can improve the reliability of arterial oxygen saturation (SpO(2)) monitoring. Twenty-four trauma patients transported to hospital were included in the study and randomly assigned to two groups: one group (n = 12) was covered with normal wool blankets, and the other group (n = 12) was treated with resistive heating blankets during transport. We recorded core temperature, shivering, skin temperature at the forearm and finger, SpO(2), and hemodynamic variables. Before randomization, both groups were comparable. On arrival at the hospital, the actively warmed patients had significantly warmer core (36.1 +/- 0.3 degrees C versus 35.5 +/- 0.3 degrees C; P < 0.001) and skin (34.1 +/- 1.5 degrees C versus 24.9 +/- 1.4 degrees C; P < 0.001) temperatures. In the actively warmed group, the pulse oximeter had significantly fewer alerts (31 versus 58) and a significantly less time of malfunction (146 +/- 42 s versus 420 +/- 256 s) and provided more constant measurements in the actively warmed group (P < 0.001). In this study we showed that active warming improves pulse oximeter monitoring quality in trauma patients during transport to the hospital. IMPLICATIONS: Clinical trials show that pulse oximeter signal quality is limited by hypothermia. In this study we show that active whole-body warming of trauma victims improves monitoring quality during transport to the hospital.