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Biomedical subjects

R Sixt

Publications and source records attributed to R Sixt.

At least 19 recordsLinked to original sources
PubMed2003

Does treatment with clean intermittent catheterization in boys with posterior urethral valves affect bladder and renal function?

PURPOSE: In boys with resected posterior urethral valves (PUV) deterioration of renal function is seen during childhood and adolescence, which may partly be caused by bladder dysfunction. We present data on renal and bladder function initially and at followup of boys with PUV in whom the bladder dysfunction has been treated since infancy. MATERIALS AND METHODS: The study included 35 boys with PUV. Bladder regimen, including early toilet training from the age of 1.5 years and detrusor relaxant drugs for the treatment of incontinence from ages 4 to 6 years, was introduced to all patients. A total of 19 boys were started on clean intermittent catheterization (CIC) at a median age of 8 months due to pronounced bladder dysfunction with poor emptying, unsafe pressure levels, high grade reflux and renal impairment. RESULTS: No serious complications of CIC have been seen during followup. Of the 19 boys 2 stopped performing CIC due to noncompliance of the parents at 1 and 3 years, respectively. Initial renal function, measured as median glomerular filtration rate (GFR) in percent of expected for age, was 60% in the CIC group and 90% in the nonCIC group. At followup at a median age of 8 years the CIC group (n = 14, 3 transplanted boys excluded) had an increase in median differential GFR (difference between followup and initial GFR) of 7% (p <0.01), which was similar increase to that of the nonCIC group. In the 2 boys who stopped performing CIC renal function deteriorated with a median differential GFR of -24%. In the CIC group detrusor instability decreased. Poor compliance was seen in 6 of the 19 boys initially and only one remained poorly compliant. In 1 of the boys who stopped performing catheterization a low compliant bladder developed. In all of the other cases bladder capacity increased more than expected for age. CONCLUSIONS: The results suggest that treatment of bladder dysfunction in boys with PUV can counteract the deterioration in renal function seen during childhood but the number of patients in our study is limited.

Child↗
PubMed2000

Renal function 16 to 26 years after the first urinary tract infection in childhood.

OBJECTIVE: To evaluate renal function in a population-based cohort with urographic renal scarring after childhood urinary tract infection (UTI). DESIGN: Follow-up investigation 16 to 26 years after the first recognized UTI. SETTING: Outpatient university clinic for children with UTI serving the local area. PATIENTS: From the original cohort of 1221 consecutive children with first UTI diagnosed during 1970 to 1979, 57 (41 females and 16 males; mean age, 24.5 years) of 68 with nonobstructive renal scarring participated as well as 51 (38 females and 13 males; mean age, 24.9 years) matched subjects without scarring. MAIN OUTCOME MEASURE: Glomerular filtration rate (GFR) measured by chromium 51-EDTA clearance, expressed as milliliters per minute per 1.73 square meters. RESULTS: Median GFR was 99 in both those with and without renal scarring. In patients with unilateral scarring, the total GFR remained unchanged over the years whereas the individual GFR of the scarred kidneys declined significantly from 46 to 39. In 7 patients with bilateral scarring, the GFR declined from 94 to 84 (P = .14); compared with those with unilateral scarring, the GFR was significantly lower at follow-up (P = .007). Median urinary albumin-creatinine ratio was 1.2 and 0.6 mg/mmol in those with scarring and those without, respectively (P = .30). CONCLUSIONS: The GFR 2 decades after the first recognized UTI in childhood was well preserved. However, a significant reduction of individual renal GFR in the unilaterally scarred kidneys indicates that further follow-up is required. Although there were few patients with bilateral scarring, a more serious prognosis can be expected among them.

Adolescent↗
PubMed1999

Consensus on renal cortical scintigraphy in children with urinary tract infection. Scientific Committee of Radionuclides in Nephrourology.

A questionnaire related to cortical scintigraphy in children with urinary tract infection was submitted to 30 experts. A wide consensus was reached on several issues related to planar images: 99mTc dimercapto succinic acid (DMSA) appears as the most appropriate tracer for renal imaging; dynamic tracers are considered to be inferior, in particular 99mTc diethylenetriaminepentaacetate, which is not recommended. The general opinion is that DMSA scintigraphy is not feasible with a minimal dose below 15 MBq, whereas the maximum dose should not be higher than 110 MBq. The dose schedule generally is based on body surface area, and sedation is only exceptionally given to children. Images are obtained 2 to 3 hours after injection, preferably with high resolution collimators; pinhole images are used by only half of the experts. Posterior and posterior oblique views are used by most of the experts, and the posterior view is acquired in supine positions. At least 200.000 kcounts or 5 minute acquisition is required for nonzoomed images. As a quality control, experts check the presence of blurred or double outlines on the DMSA images. Color images are not used and experts report on film or directly on the computer screen. As far as normal DMSA images are concerned, most experts agree on several normal variants. Hydronephrosis is not a contraindication for DMSA scintigraphy but constitutes a pitfall. Differential renal function generally is measured, but no consensus is reached whether or not background should be subtracted. Most of the experts consider 45% as the lowest normal value. A consensus is reached on some scintigraphic aspects that are likely to improve and on some others that probably represent persistent sequelae. There is a wide consensus for the systematic use of DMSA scintigraphy for detection of renal sequelae, whereas only 58% of the experts are systematically performing this examination during the acute phase of infection.

Child↗
PubMed1999

Early and late metabolic alterations in children and adolescents with a kock urinary reservoir.

OBJECTIVE: To assess the early and late metabolic effects of urinary diversion in children and adolescents with a Kock urinary reservoir. PATIENTS AND METHODS: Thirteen children (aged 10.8- 16 years) and seven adolescents (aged 16-18 years; 10 girls and 10 boys), underwent surgery for congenital urinary incontinence. They were followed for 3-10 years (mean 6.5), divided into an early (3 months to 2 years) and a late (2-10 years) period, and assessed for renal function and any metabolic effects. RESULTS: At the early and late follow-up, one of 19 and three of 16 patients, respectively, had metabolic acidosis. Hyperchloraemia was present in four of 20 patients at the early and in eight of 18 at the late follow-up. Serum creatinine was increased in four of 20 patients at the early and eight of 18 at the late follow-up. In patients with infrequent reservoir emptying (</=4 times/day), the serum creatinine level was increased in seven of 13 at the early and eight of 10 at the late follow-up (P<0.05). The glomerular filtration rate was below normal in four of 20 patients preoperatively, in six of 19 at the early and in eight of 18 at the late follow-up. CONCLUSIONS: The continent ileal reservoir in children and adolescents produces similar changes to those previously reported in adults. However, almost all patients with metabolic disorders were younger than 16 years at operation. The pre-existing impairment of renal function, together with associated congenital anomalies, mental and/or physical disorders, young age, recurrent urinary tract infections and infrequent reservoir emptying, leads to deterioration in renal function after the Kock operation. Even with this risk, the Kock pouch remains a viable alternative to other forms of continent urinary diversion, because it has a wide calibre stoma, allowing large-bore catheters, and is therefore especially suitable for individuals with weak hand function, e.g. quadriplegic or meningomyelocele patients. However, as shown by these results, the child with a Kock pouch requires continuous medical attention.

Acid-Base Equilibrium↗
PubMed1999

Evaluation of Kock urinary reservoir function in children and adolescents at 3-10 years' follow-up.

The aim of this study was to evaluate Kock reservoir function in children and adolescents operated for congenital urinary incontinence and to determine the complication rate. Reservoir function was investigated in 13 children (age range 10.8-16 years) and 7 adolescents (age range 16-18 years) through enterocystometry, enterocystoscopy and patient history. Patients were followed up for 3-10 years. The follow-up was reported as early (3 months-2 years) and late (2-10 years) postoperative periods. At early follow-up reservoir capacity was high in four patients and normal in the remaining patients. A low reservoir pressure was accompanied by high capacity and compliance. On enterocystometry first sensation for emptying was experienced in 82% of patients at early follow-up and 92% at late follow-up. Reservoir contractions were recorded in 60% of patients at early follow-up and 65% at late follow-up. The contractions were recorded at an average reservoir capacity of 270 ml at early follow-up and 340 ml at late follow-up. The complication rate was high in the child group compared with that in adolescents. Of 13 patients with at least one reservoir complication 10 were from the child group. Nipple dysfunction (angled nipple, prolapsed or stenosed stoma) occurred in 35% of patients, stones in 40% and bleeding during catheterization in 15%. Revision was performed in 38% of the child group and 15% of the adolescents. Reservoir perforation was observed in two patients at 6 and 9 years postoperatively. At late follow-up continence was excellent in 17 of 19 patients and good in 2. We conclude that the Kock reservoir is a good modality for urinary diversion, but the complication incidence is high in the child group (<16 years). Stability of the reservoir in terms of volume and low internal pressures was achieved one year after operation, except in the patients with infrequent reservoir emptying. A time-related increase in the reservoir sensitivity and contractility was reported on enterocystometry. Nipple dysfunction is common during the first two years after surgery, particularly in the child group. Stones may form 3-4 years after surgery. Satisfactory continence was achieved in all patients, although a revisional operation was necessary in some patients in order to obtain permanent continence.

Adolescent↗
PubMed1999

Administered activity of 99Tcm-MAG3 for gamma camera renography in children.

A method of calculating the activity of 99Tcm-MAG3 to be administered to children of different ages has been developed and evaluated. The suggested administered activity schedule is only valid for estimation of split renal function. The activity required to obtain the same count rate over the kidneys for all ages was calculated as a fraction of the activity administered to an adult by using a biokinetic model and taking attenuation effects into account. The activity schedule is based on the age of the child and was tested using renograms from patients of different ages. Statistical noise was added to the smoothed renograms simulating an injected activity corresponding to 45 MBq for an adult. The precision in the determination of split renal function calculated with four different methods was determined for 500 simulated renograms. The precision was approximately the same for all ages, but varied with the method used. The activity to be administered to a very small child is 90% of the adult activity, decreases to less than 50% between 2 and 5 years of age, and then slowly increases to 100% as the child grows to adulthood.

Adolescent↗
PubMed1999

Imaging of renal scarring.

Children with urinary tract infection should be investigated and followed up, as those with pyelonephritis may develop renal scarring. In this review, after discussing the advantages and disadvantages of various imaging modalities for diagnosis of renal scarring, it is concluded that DMSA scintigraphy and urography can both be used to detect significant renal scarring. With DMSA scintigraphy, small renal lesions (functional uptake defects) not seen at urography will also be detected. The long-term clinical significance of these lesions is, as yet, unknown. A normal DMSA scintigraphy after infection indicates low risk for clinically significant damage. In order to allow acute, reversible lesions to first disappear, a follow-up DMSA examination should not be performed until at least 6 mo after the acute infection. Ultrasonography in isolation cannot be recommended for the diagnosis of renal scarring.

Chelating Agents↗
PubMed1998

Technetium-99m mercaptoacetyltriglycine clearance values in children with minimal renal disease: can a normal range be determined?

Use of technetium-99m labelled mercaptoacetyltriglycine (99mTc-MAG3) simplifies and improves the quantification of renal clearance in children by virtue of its permanent availability, good imaging properties and low radiation exposure. Due to the lack of reference values for 99mTc-MAG3 clearance in children, the Paediatric Task Group of the EANM initiated a multicentre study to evaluate 99mTc-MAG3 clearance values in children with minimal renal disease. One hundred and twenty-five children aged between 12 months and 17 years, classified as renally healthy using defined diagnostic criteria, were included in the study. 99mTc-MAG3 clearance was calculated using an algorithm on the basis of a single blood sample taken at any time between 30 and 40 min after tracer injection. In addition, the absolute 99m-Tc-MAG3 clearance values were normalized to body surface area. For further evaluation the children were classified into several groups according to age. There was a continuous increase in non-corrected 99mTc-MAG3 clearance values from the age of 1 year up to the age of 17 years (mean value <2 years: 98+/-57 ml/min; mean value >8 years: 208+/-66 ml/min). Normal clearance values for adults were achieved by the age of 8 years. Analysis of the relationship between non-corrected clearance and age yielded a correlation coefficient of r=0.7. When these absolute clearance values were normalized to body surface area, we found nearly constant clearance values for all age groups, with a mean clearance value of 315+/-114 ml/minx1.73 m2. The correlation coefficient for the relationship between normalized clearance and age was r=0.28. In conclusion, the clearance of 99mTc-MAG3 increases continuously throughout childhood into adolescence due to the maturation and growth of the kidney. After normalization of the absolute clearance to body surface area, no correlation between clearance and age could be proven.

Child↗
PubMed1998

Five-year study of medical or surgical treatment in children with severe vesico-ureteral reflux dimercaptosuccinic acid findings. International Reflux Study Group in Europe.

UNLABELLED: The results of serial dimercaptosuccinic acid (DMSA) imaging over 5 years are reported in 287 children with severe vesico-ureteral reflux entered into the European Branch of the International Reflux Study in Children. The children were randomly allocated to medical (n=147) or surgical (n=140) management and DMSA studies were performed during the follow up period at least 6 months after any urinary tract infection. Abnormal images were classified into four types: (1) large polar hypodensity with normal renal outline; (2) peripheral photon deficient defect(s) in a non-deformed kidney; (3) small renal image with normal contour; and (4) peripheral defect(s) with resultant irregularity of the renal outline. The DMSA findings were abnormal at entry in 235 (82%) with no difference in incidence or severity between the two treatment groups. During follow up, deterioration was observed in 25 medically and 23 surgically treated patients and comprised image deterioration alone in 17, image deterioration with corresponding reduction in differential function in 16 and reduction in relative function without image change in 15, with similar distribution between the two treatment groups. Deterioration was more frequent in children entering the study under the age of 2 years and in those with grade IV rather than grade III reflux. These findings, showing no difference in outcome between children managed surgically or medically, are consistent with the radiological results already published. CONCLUSION: In the International Reflux Study the DMSA scintigraphic data showed no difference in outcome between children managed surgically or medically.

Child↗
PubMed1998

Cardiac output and pulmonary gas exchange at maximal exercise after atrial redirection for complete transposition.

AIMS: To assess the determinants of exercise capacity and exercise oxygenation after atrial redirection for complete transposition. METHODS AND RESULTS: At graded bicycle ergometry, including respiratory and arterial blood gas analyses, intra-arterial blood pressure recording, and cardiac output determination (dye-dilution technique), we tested 17 post-Mustard/Senning patients, 8.9-22.0 years old (mean 14.5, SD 4.0). Reference data were obtained by similar methods. At maximal exercise, oxygen uptake (29.6 ml x kg(-1) x min(-1)) and heart rate (167 beats x min(-1)) were low (P<0.001). Right-to-left shunts were detected in five patients. Arterial oxygen partial pressure and saturation fell in all subjects (P<0.0001). In 15/16 (94%) the alveolar-arterial oxygen partial pressure difference was > +2 SD. In 13/15 (87%) stroke volumes fell during exercise. Cardiac output per oxygen uptake was low (P<0.0001), which implies a high arteriovenous oxygen difference and a low mixed venous oxygen content at peak exercise. CONCLUSION: The low exercise capacity was caused by a combination of low maximally attained heart rate and falling stroke volumes. The impaired arterial oxygenation may be caused by a combination of pulmonary ventilation/perfusion mismatch, a low mixed venous content and atrial shunting in some patients.

Adolescent↗
PubMed1998

Evaluation of DMSA scintigraphy and urography in assessing both acute and permanent renal damage in children.

PURPOSE: To evaluate dimercaptosuccinic acid (DMSA) scintigraphy and urography in the detection of renal involvement in children with urinary tract infection (UTI) in order to identify patients with a high risk of developing renal damage. MATERIAL AND METHODS: A total of 157 children (median age 0.4 years, range 5 days to 5.8 years) with first-time symptomatic UTI were examined scintigraphy (with an assessment of renal area involvement) and urography at the time of UTI and 1 year later. All evaluations were made blindly. RESULTS: Of the total 314 kidneys, 80 (25%) were abnormal at initial scintigraphy. Of these 80 kidneys, 44 (55%) had normalized at follow-up. Of the 234 initially normal kidneys, 29 (12%) were abnormal at follow-up. One year after UTI, abnormalities were seen in 59 children at scintigraphy and in 18 children at urography. Renal area involvement was larger and split function abnormalities more common in kidneys that were abnormal at both scintigraphy and urography than in kidneys with only scintigraphic abnormalities. CONCLUSION: Quantitation of renal area involvement and split renal function at early scintigraphy would seem to be useful in identifying patients at risk of developing renal damage. Urography at 1 year after infection identified mainly those with the most severe scintigraphic abnormalities. The clinical importance of scintigraphic abnormalities that are not confirmed by urography is not known.

Acute Disease↗