The effect of biphasic cuirass ventilation on peripheral lymphatic function in young adults

Positive pressure ventilation increases the intrathoracic pressure and the central venous pressure, impeding venous return to the heart. Likewise, both central and peripheral lymphatic function is haltered during positive pressure ventilation, presenting as a possible explanation for fluid retention and edema in post-operative and intensive care unit patients. We aimed to examine the effects of biphasic cuirass ventilation on the peripheral lymphatic system. Peripheral lymphatic function was examined in twenty healthy, young adults during spontaneous breathing and during biphasic cuirass ventilation. The peripheral lymphatic function was assessed with near-infrared fluorescence imaging, and the microvascular circulation was assessed with strain gauge plethysmography. Mean peripheral lymphatic contraction frequency (mean ± SD) was 1.46 $\pm$ 0.73/min at baseline and 1.43 $\pm$ 0.76/min during biphasic cuirass ventilation. There was no significant difference (mean difference = 0.03, 95% CI: -0.23-0.29, p = 0.81, n = 19). Capillary filtration rates did not differ between baseline and biphasic cuirass ventilation across all pressure levels (F(1,18) = 1.13, p = 0.30). Likewise, there were no significant differences in isovolumetric pressures (mean difference = -2.61, 95% CI: -8.92-3.71, p = 0.39, n = 15), or capillary filtration coefficients (mean difference = 1.21 × 10^-4, 95% CI: -4,87 × 10^-4 - 7.29 × 10^-4, p = 0.68, n = 19). We observed no changes in peripheral lymphatic activity in awake, healthy, young adults during BCV.