Institute of Anaesthesia and Intensive Care, Catholic University of Sacred Heart, Rome, Italy.
Crit Care Med. 2011 Feb;39(2):344-8. doi: 10.1097/CCM.0b013e3181ffe0d2.
In patients affected by intra-abdominal hypertension, bladder or gastric pressure measurement may be usefully integrated by ultrasounds in order to detect early hemodynamic impairment. The purpose of this study was to search for changes in abdominal vein size and flow induced by intra-abdominal hypertension.
Physiologic study.
Postoperative intensive care unit of a university hospital.
Sixteen healthy volunteers.
Four echographic assessments of vessel sizes and blood velocities were randomly performed in the following settings: 1) baseline, 2) intra-abdominal hypertension simulated by a tight pelvic stabilizer around the waist, 3) noninvasive ventilation with a facial mask, and 4) intra-abdominal hypertension plus noninvasive ventilation.
The model of intra-abdominal hypertension was validated in eight subjects by measuring gastric pressure. During intra-abdominal hypertension, 1) the inferior vena cava was compressed (significant decrease of both anteroposterior and lateral diameters) and deformed (decreased anteroposterior/lateral diameter ratio), and deformation, but not compression, was attenuated by noninvasive ventilation associated with intra-abdominal hypertension; 2) the portal vein was also compressed (decreased diameter); and 3) blood velocities did not change significantly in the inferior vena cava, portal vein, right suprahepatic vein, or right external iliac vein. In the receiver operating characteristic curve analysis, an inferior vena cava section area (normalized for body surface) of lower than 1 cm²/m² discriminated between intra-abdominal hypertension presence and absence with a sensitivity of 65.6% and a specificity of 87.5% (p = .0001). Noninvasive ventilation alone did not significantly affect vein sizes and velocities. The resistive index, calculated by pulse wave Doppler signal from segmental branches of the right renal artery, increased slightly, but significantly, during intra-abdominal hypertension alone, suggesting an increase of intrarenal pressure.
Simulated intra-abdominal hypertension was associated with decreased inferior vena cava section area and increased resistive index in renal arteries. Further studies are now needed to investigate whether these changes may be of value to integrate bladder or gastric pressure measurement in clinical practice.
在腹内高压患者中，膀胱或胃压测量可通过超声检查有效地进行整合，以早期发现血流动力学损害。本研究旨在寻找腹内高压引起的腹部静脉大小和血流变化。
生理研究。
一家大学医院的术后重症监护病房。
16 名健康志愿者。
在以下情况下随机进行 4 次血管大小和血流速度的超声评估：1）基础，2）通过腰部周围的紧身骨盆固定器模拟腹内高压，3）使用面罩进行无创通气，4）腹内高压加无创通气。
在 8 名受试者中通过测量胃压验证了腹内高压模型。在腹内高压期间，1）下腔静脉受压（前后径和横径均显著减小）并变形（前后径/横径比减小），无创通气可减轻变形，但不能减轻受压；2）门静脉也受压（直径减小）；3）下腔静脉、门静脉、肝上右静脉和右髂外静脉的血流速度无明显变化。在受试者工作特征曲线分析中，下腔静脉截面积（按体表面积归一化）低于 1cm²/m²可区分腹内高压存在和不存在，其灵敏度为 65.6%，特异性为 87.5%（p=0.0001）。无创通气单独使用不会显著影响静脉大小和速度。单独腹内高压时，右肾动脉节段分支的脉冲波多普勒信号计算的阻力指数略有但显著增加，提示肾内压升高。
模拟腹内高压与下腔静脉截面积减小和肾动脉阻力指数增加有关。目前需要进一步研究这些变化是否有助于将膀胱或胃压测量整合到临床实践中。
