Christ F, Dellian M, Goetz A E, Gamble J, Messmer K
Institute of Anaesthesiology, Ludwig Maximilians University, Munich, Germany.
Microcirculation. 1997 Mar;4(1):75-81. doi: 10.3109/10739689709148319.
Venous congestion plethysmography enables noninvasive assessment of microvascular filtration capacity (Kf) in limbs. However, increases in fluid filtration might alter the balance of Starling forces: for example, progressive increases in interstitial fluid pressure (Pi) would reduce net fluid flux, thus underestimating Kf. Furthermore, elevation of cuff pressure to values close to diastolic blood pressure, as used in the protocol, may be itself impair tissue perfusion with unknown effects on the microvascular parameters investigated.
Pi was measured in healthy volunteers (n = 14) with a modified "Wick in needle" technique during small (8 mm Hg) cumulative increases in venous pressure (0-95 mm Hg). Changes in the hemoglobin (Hb) concentration, oxygenated hemoglobin (HbO2) concentration and oxidized cytochrome aa3 concentration were assessed in the calf using noninvasive near-infrared spectroscopy. Skin red blood cell flux close to the strain gauge was evaluated by laser Doppler fluxmetry.
Pi at control was -0.89 +/- 0.8 mm Hg and during elevation of venous pressure remained constant until a cuff pressure of 30 mm Hg was reached. It rose thereafter to 1.57 +/- 1.3 mm Hg (mean +/- SD). Skin red cell flux was significantly reduced when cuff pressure exceeded 30 mm Hg and following cuff deflation, evidence of reactive hyperemia was obtained. Hb concentration increased significantly as a result of venous pressure elevation. No change in either HbO2 or cytochrome aa3 concentration was observed as long as cuff pressure remained under diastolic blood pressure.
The small increase in Pi together with an absence of impaired tissue oxygenation during the venous congestion plethysmography protocol described by Gamble et al. supports the contention that this protocol enables accurate assessment of filtration capacity.
静脉充血体积描记法能够对肢体的微血管滤过能力（Kf）进行无创评估。然而，液体滤过增加可能会改变Starling力的平衡：例如，间质液压力（Pi）的逐渐增加会降低净液体通量，从而低估Kf。此外，如该方案中所使用的，将袖带压力升高至接近舒张压的值本身可能会损害组织灌注，对所研究的微血管参数产生未知影响。
在健康志愿者（n = 14）中，采用改良的“针芯灯芯”技术在静脉压力（0 - 95 mmHg）小幅（8 mmHg）累积增加期间测量Pi。使用无创近红外光谱法评估小腿中血红蛋白（Hb）浓度、氧合血红蛋白（HbO2）浓度和氧化细胞色素aa3浓度的变化。通过激光多普勒血流仪评估靠近应变片处的皮肤红细胞通量。
对照时Pi为 -0.89 ± 0.8 mmHg，在静脉压力升高期间保持恒定，直到达到30 mmHg的袖带压力。此后它升至1.57 ± 1.3 mmHg（平均值 ± 标准差）。当袖带压力超过30 mmHg时，皮肤红细胞通量显著降低，在袖带放气后，获得了反应性充血的证据。由于静脉压力升高，Hb浓度显著增加。只要袖带压力保持在舒张压以下，HbO2或细胞色素aa3浓度均未观察到变化。
Gamble等人描述的静脉充血体积描记法方案中Pi的小幅增加以及组织氧合未受损支持了该方案能够准确评估滤过能力的观点。
