Influence of lower limb pneumatic compression on pulmonary artery temperature

Abstract

Intermittent pneumatic calf compression increased lower limb venous return, causing acute but transient decreases in pulmonary artery blood temperature. This did not affect the accuracy of thermodilution cardiac output measurements that were made using 10 mL of either cold or room temperature injectate.

Effect of lower limb compression devices on thermodilution cardiac output measurement*

“…Possible explanations for the apparent disparity between our results and that of Horiuchi et al (20), who failed to demonstrate significant changes in CO with pneumatic calf compression, concern two key differences: the type of pneumatic compression device used and the timing of CO determinations. In the study by Horiuchi et al (20), NCDs were used, whereas we used SCDs that inflate sequentially from the ankle toward the knee.…”

“…The second key difference is in the timing of CO measurements in relation to the inflation cycle of the device, which may affect CO determination. The exact timing of CO measurement in the Horiuchi et al (20) study is not explicitly indicated. In our study, the timing of CO determinations occurs at two specific points in the inflation cycle, 2-4 secs (T2) and 4 -8 secs (T3).…”

“…In addition to these major differences, there may be differences in the severity of illness between the studies. For example, in the Horiuchi et al (20) study, no patients with hemodynamic instability were included, and we do not know if any patients were on mechanical ventilation.…”

“…Although not specifically measured by Horiuchi et al (20), peripheral limb temperatures in the ICU are generally cooler relative to core body temperature by about 2-4°C (21). Horiuchi et al (20) further supported their hypothesis by demonstrating that bilateral NCD inflation resulted in lower pulmonary artery temperatures than if inflated on a single calf.…”

“…Horiuchi et al (20), using the thermistor readings from a continuous thermodilution cardiac output PAC to continuously monitor pulmonary artery temperature during the inflation cycle of a NCD, demonstrated significant reproducible transient decreases in pulmonary artery temperature after NCD inflation. They hypothesized that during the inflation cycle of the calf NCD, an increase in the femoral venous flow brings an increased volume of cooler blood from the lower limbs to the heart, resulting in a decrease in pulmonary artery temperature.…”