Studies on intrarenal pressure using a new balloon method (author's transl)

Abstract

The intrarenal pressure (IRP) was measured in 24 dogs anesthetized with pentobarbital sodium, weighing 7-13kg. The needle method has chiefly been used for the measurement of renal tissue pressure, but it has been pointed out that it involves many problems. In the present study was used what is called the balloon method, which has never been reported previously. The probe used was a modification of a flow directed catheter (SWAN-GANZ) (Fig. 1). The probe was proved to be of high precision by measuring already known pressure values with it for testing purposes (Fig. 2). The left kidney of each dog was stuck with this probe up to a given depth to measure the IRP. The left ureter was sectioned, and a ureteral catheter was inserted into the pelvis to measure the intrapelvic pressure (IPP). The renal blood flow (RBF) was also measured in part of the dogs. The dogs were transfused with 4-6ml/hour/kg of isotonic saline solution during the experiments.The following results were obtained:1. Measurement of IRP in a state free of ureteral obstruction (free-flow state). The mean pressure value was 11.9±3.7mmHg (range 6.1-18.5) (Table 1).2. Measurement of IRP in complete ureteral obstruction. The IRP rose with a rise in the IPP. There was an upper limit to each pressure. The mean maximum IRP value was 43.6±4.4mmHg (range 36.1-52.0), and the mean maximum IPP value was 58.2±6.9mmHg (range 44.0-69.0). (Table 2, Fig. 3, 4).3. Measurement of RBF in complete ureteral obstruction. The RBF increased with a rise in the IPP and IRP. The mean increase of RBF was 25.8% from the control level. (Table 3, Fig. 5).4. Measurement of IRP during Mannitol loading in a free-flow state. During Mannitol loading, the IRP rose with the mean maximum pressure value of 29.2mmHg. The RBF also increased slightly and temporarily (Table 4, Fig. 6).5. Measurement of IRP and RBF in occlusion of renal vein in a free-flow state. On occlusion of the renal vein, the IRP rose, with the maximum pressure value of 61.3mmHg, and with the mean, 53.4±5.3mmHg (range 46.4-61.3). The RBF markedly decreased. Reopening the blood flow was followed by a rapid restoration to the control level (Table 5, Fig. 7, 8).6. Measurement of IRP and RBF in occlusion of renal artery in a free-flow state. On occlusion of the renal artery, the IRP dropped, with the minimum pressure of 3.1±0.8 mmHg (range 1.7-3.7). The RBF stopped. Reopening the blood flow was followed by a rapid restoration to the control level (Table 6, Fig. 9, 10).7. The merits and demerits of the balloon method have been presented.