通过连续热稀释技术对人体绝对肾血流量床旁测量的验证

Haywood G A, Stewart J T, Counihan P J, Sneddon J F, Tighe D, Bennett E D, McKenna W J

Department of Cardiological Sciences, St. George's Hospital Medical School, London, UK.

Crit Care Med. 1992 May;20(5):659-64. doi: 10.1097/00003246-199205000-00019.

BACKGROUND AND METHODS

There is a clinical need for a system that would allow rapid assessment of renal blood flow in patients with oliguric circulatory shock. A local, continuous thermodilution technique for the measurement of renal venous blood flow, using readily available equipment, was developed. To test the hypothesis that this system would allow measurement of renal blood flow in clinical situations, we compared simultaneous measurements made by the continuous thermodilution technique with measurements of: a) absolute flow measured by volumetric collection in an in vitro flow model; b) renal arterial blood flow measured by electromagnetic flow probe under changing hemodynamic conditions in nine pigs; and c) calculated renal blood flow derived from a clearance technique in 16 patients after cardiac catheterization. The technique utilizes a short-duration, constant infusion of room temperature normal saline into the renal vein via a retrograde thermodilution catheter, with measurement of flow at a thermistor 1 cm back from the tip of the catheter.

RESULTS

The method measured absolute blood flow in an in vitro model, with a correlation coefficient of .99 over blood flows ranging from 55 to 885 mL/min (r2 = .98). There was a .92 correlation coefficient with renal arterial blood flow measured by electromagnetic flow probe in a pig model (r2 = .85), and a .8 correlation with simultaneous measurement of renal blood flow by corrected iodohippurate clearance in humans (r2 = .64). Compared with electromagnetic flow probe measurements, a single measurement by the thermodilution technique would be accurate to within 80 mL/min in 95% of cases. Variability between individual measurements, expressed as the mean of the coefficient of variance for each patient, was 5.5 +/- 3.7%.

CONCLUSIONS

This technique is simple to use, requires only venous cannulation and injection of normal saline, and allows rapidly repeatable, immediately available measurements of renal blood flow in a wide range of clinical circumstances, including severe renal impairment or anuria.

背景与方法

临床上需要一种能够快速评估少尿性循环休克患者肾血流量的系统。我们开发了一种使用现成设备的局部连续热稀释技术来测量肾静脉血流量。为了验证该系统能够在临床情况下测量肾血流量这一假设，我们将连续热稀释技术的同步测量结果与以下各项测量结果进行了比较：a）在体外血流模型中通过容量收集测量的绝对血流量；b）在九只猪的血流动力学条件变化时通过电磁血流探头测量的肾动脉血流量；c）在16例心脏导管插入术后患者中通过清除技术计算得出的肾血流量。该技术通过逆行热稀释导管向肾静脉短时间、持续输注室温生理盐水，并在距导管尖端1厘米处的热敏电阻测量血流量。

结果

该方法在体外模型中测量绝对血流量，在55至885毫升/分钟的血流量范围内相关系数为0.99（r2 = 0.98）。在猪模型中与通过电磁血流探头测量的肾动脉血流量的相关系数为0.92（r2 = 0.85），在人体中与通过校正碘马尿酸清除率同步测量肾血流量的相关系数为0.8（r2 = 0.64）。与电磁血流探头测量结果相比，热稀释技术单次测量在95%的情况下准确至80毫升/分钟以内。个体测量之间的变异性，以每位患者方差系数的平均值表示，为5.5±3.7%。