Atraumatic method of renal blood flow estimation by 133Xenoninhalation and its application to transplanted kidneys

Non-invasive measurement of organ blood flow can be achieved by tracing the elimination patterns of 133Xe administered by inhalation. An adaption of the method for the estimation of renal blood flow was developed. The 133Xe is accumulated in the tissue by re-breathing for 1 min and the time course of its washout from the kidney is followed for 14 min thereafter. Normal values were determined in ten dogs and forty-five healthy human volunteers. In man they were similar to results obtained with 131I-hippuran clearance. When flow rates were between 250 and 600 ml/100 g/min the correlation coefficient was 0.84. Only in cases with high cortex flow rates (greater than 600 ml/100 g/min) did the inhalation method give values higher than those determined by the 131I-hippuran clearance. In dogs the results closely correlated with results obtained by direct intra arterial xenon injection (r = 0.96). The value of the inhalation method in routine examination of patients with kidney transplants and its suitability for the early detection of ongoing rejection is demonstrated.