J. Brøchner-Mortensen

Renal function and body composition before and after intestinal bypass operation in obese patients

The distribution volume of [51Cr]EDTA, as an estimate of the extracellular fluid volume (ECV), glomerular filtration rate (GFR) and urinary excretion rate of endogenous creatinine (uc), as an index of muscle mass, were determined in obese patients before and after intestinal bypass operations. The results were compared to those in non-obese controls with the same age and height. GFR, ECV and uc were all significantly increased to the same extent (about 40%) in thirteen patients examined before operation (overweight 86-159%). Means of the ratio GFR/ECV and standard GFR (i.e. GFR corrected to a body surface area of 1.73 m2) did not differ from those in the controls. In eight patients examined before and 1 year after operation (body weight reduction 23-79 kg), GFR were unchanged and remained normal. ECV was significantly increased by 20% in nineteen patients investigated 1-7 years after operation (mean overweight 42%) whereas the mean of uc did not differ from that in the controls. Using the ratio GFR/ECV as reference for the function of the kidneys, the present study shows that the renal function in otherwise healthy obese subjects is normal throughout the whole range of overweight, and that standard GFR is a reliable parameter to assess the renal function even in patients with extreme obesity. The body weight reduction following intestinal bypass operation is in part due to fall in muscle mass, but the results suggest that a normal relation between body cell mass and body water is not achieved.

Renal haemodynamics and extracellular homeostasis during the menstrual cycle

Renal haemodynamics and extracellular homeostasis during the menstrual cycle were studied in 14 healthy women (age 21-41 years) who were not taking oral contraceptives in the follicular (Period I) and luteal phase (Period II). The glomerular filtration rate [( 51Cr] EDTA clearance) and the effective renal plasma flow ([125I] hippuran clearance) increased from Period I to II by a median of 6.3% (95% confidence interval (CI): 0.6-9.2%) and 7.3% (95% CI: -0.4-22%) respectively. Serum sodium decreased from period I to II (p less than 0.01) by a median of 1 mmol/l (95% CI: -2.0 to -0.5 mmol/l) and the urinary excretion rate of potassium increased (p less than 0.02) from a median value of 35 mumol/min in Period I to 45 mumol/min in Period II. The extracellular fluid volume did not change between the two periods but the concentration of water in serum increased (p less than 0.05) from a median value of 91.7-92.0 g/100 g in Period II. Serum total protein and serum albumin both showed a borderline statistically significant decrease from Period I to II. The investigation demonstrated a number of physiological and biochemical changes from the follicular to the luteal phase, most of which in a lower scale mimic well known changes that occur during pregnancy.

Long posterior flap versus equal sagittal flaps in below-knee amputation for ischaemia

We analysed the complication rate in 140 below-knee amputations in relation to surgical technique and the presence of diabetes. In all cases, the skin perfusion pressure was measured below the knee before operation to provide an objective evaluation of the microcirculation. In diabetic patients we found a significantly higher complication rate after using a long posterior flap than after equal sagittal flaps. No such difference could be demonstrated in non-diabetic patients. We suggest that the higher incidence of atherosclerotic lesions in the three major arteries below the knee in diabetic patients may account for the difference. We recommend the use of the sagittal technique for below-knee amputation in diabetic patients.

Selection of lower limb amputation level not aided by transcutaneous pO2 measurements.

The transcutaneous oxygen pressure measurements were evaluated as supplementary ones for predicting stump healing in 58 below-the-knee and 16 above-the-knee amputations; the lower level was selected if the skin perfusion pressure was greater than 30 mm Hg below the knee. The failure rates in below-the-knee and above-the-knee amputations were 17 and 25 percent, respectively, and unrelated to the transcutaneous oxygen pressure measured at the amputation level. We conclude that no further information is acquired by measuring transcutaneous oxygen pressure.

Results of amputation for gangrene in diabetic and non-diabetic patients. Selection of amputation level using photoelectric measurements of skin-perfusion pressure.

Evaluation was done of 235 patients who had had 273 primary amputations for gangrene. Measurements of local skin-perfusion pressure or systolic blood pressure were made in 222 limbs (188 patients). For the other fifty-one limbs, for which no measurements of pressure were available, the surgeon elected to perform an above-the-knee amputation in nine of seventeen diabetic limbs and a below-the-knee amputation in eight. An above-the-knee amputation was selected by the surgeon for thirty-two of thirty-four non-diabetic limbs and a below-the-knee amputation, for two for which no measurements of pressure were available. Local skin-perfusion pressure was measured distal to the knee before amputation, using a standardized photoelectric technique in 203 limbs and systolic blood-pressure measurements in nineteen. Skin-perfusion pressure was also measured above the knee in seventy-six of the 222 limbs in which a pressure was determined below the knee. These measurements were made available to the surgeon for use as an adjuvant guide to clinical assessment in selecting the appropriate level of amputation. Seventy-four patients (ninety-two amputations) had diabetes and 114 patients (130 amputations) did not. The limbs of the diabetic patients had a significantly higher skin-perfusion pressure at the below-the-knee level (p less than 0.001) than did those of the non-diabetic patients. The ratios of below-the-knee to above-the-knee amputations for the diabetic and non-diabetic patients were 3.8 to one and 1.3 to one (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of 51Cr-EDTA clearance in infants by a single capillary blood sample

A method by which 51Cr-EDTA plasma clearance is determined from a single capillary blood sample (Clsc) was studied in 52 children less than 1 year old. The Clsc is calculated as the ratio between the injected dose and the total area under a transformed monoexponential function. The monoexponential curve is determined from the plasma activity 120 min after i.v. single injection of 51Cr-EDTA and a hypothetical initial activity calculated as the injected dose divided by the distribution space of 51Cr-EDTA. The distribution space was estimated from the body surface area. The rate constant of the monoexponential function is transformed by an empirically determined factor to make the area under the curve identical to the area under the true plasma disappearance curve. The Clsc was compared with 51Cr-EDTA plasma clearance (range 18-146 ml/min/1.73 m2) determined by a standard method from five capillary blood samples (Cl). The regression of Cl on Clsc did not differ from the line of identity, the SD being 5.9 ml/min/1.73 m2. In advanced renal failure the one-sample method is very sensitive to inaccuracies in the distribution space estimate and, accordingly, this method should be used only when the clearance value is predicted higher than 30 ml/min/1.73 m2.