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Biomedical subjects

K M Jensen

Publications and source records attributed to K M Jensen.

At least 19 recordsLinked to original sources
PubMed1992

[Testing an ultrasonic scanner for determination of urinary bladder volume].

Bladderscan BVI 2000 is a portable ultrasound scanner, specially constructed for determination of bladder volume. We have tested this scanner for accuracy, systematic errors and the training required to use it. The bladder volumes measured by ultrasound scanning were compared with the true volumes. Fifty-six measurements were made. We found the accuracy of BVI 2000 sufficient to determine bladder volumes as either small or large. We found no systematic errors. No special training is required to use the scanner. The device is thus useful in most clinical situations when greater accuracy than indicated here is not necessary.

Evaluation Studies as Topic↗
PubMed1992

Effects of sulfide and low redox potential on the inhibition of nitrous oxide reduction by acetylene in Pseudomonas nautica.

Membrane introduction mass spectrometry was used to investigate the inhibitory effect of acetylene on the nitrous oxide reductase activity of intact cells of Pseudomonas nautica. We studied the effects of the concentrations of nitrate and sulfide, and the redox potential, which have all been implicated in causing a decrease in the inhibitory effects of acetylene during measurements of denitrification in natural environments. There was no evidence that the concentration of nitrate influenced the effect of acetylene. Lowering the redox potential with the reductant Ti(III)-nitrilotriacetate caused a slight alleviation of acetylene inhibition. Much greater effects at the same redox potential were obtained with concentrations of sulfide in the range 1-10 microM.

Acetylene↗
PubMed1992

Age-related variation in urinary flow variables and flow curve patterns in elderly males.

A group of randomly selected males, over 50 years of age, was examined with regard to history and urinary flow rate. Originally, the group had comprised 93 men without voiding problems, 15 who, although suffering from voiding problems, had not yet contacted their doctor, and 4 who had contacted their doctor because of voiding problems. Five years later the data were re-examined and 61 men were fully investigated again; in the remaining 51 patients only the history was updated. The 2 sets of data were evaluated separately as 2 cross-sectional investigations and as paired data sets by means of non-parametric statistical analysis. All uroflow variables were considered, i.e. Qmax, Qave, Qmax-time, Q "corrected", volume and the ratio Qmax/Qmax-time. In addition, the flow curve configuration was classified as normal or abnormal. When compared as 2 cross-sectional investigations, the latter confirmed the results of the first. Qmax, Qave, Q "corrected" and volume decreased with advancing age, but no correlation could be demonstrated between Qmax-time and age. The flow curve pattern altered, so that a normal flow curve was seldom seem at an advanced age. Uroflow variables tended towards the abnormal with advancing years and symptoms increased concurrently. These changes were largely accepted by the elderly males. Thus the decision to operate for benign prostatic hyperplasia should be based on both history and urinary flow.

Aged↗
PubMed1991

[Clinical continuing education of younger physicians. A pedagogic trial with postgraduate clinical training using the clinical decision process].

The aim of this study was to improve the clinical training of the staff of a department of internal medicine. A total of 16 clinical pathological conferences with patient demonstrations were given. The doctor in charge of the conference motivated his choice of patient and made a critical review of the clinical decision process according to a 16 item check list. The median time used for planning of the presentation was five hours, range 2.5-8 hours. Sixteen of the participants (94%) found the training programme of very high or high quality while 1 (6%) found it less good. Fifteen (88%) of the doctors indicated higher clinical skill after than before the conferences (p less than 0.01). The registrars revealed a significantly better improvement of their clinical skills than did the senior registrars and consultants (p less than 0.05). The median educational value of the items of the check list was stated to be 1.3 (0-2). Statement of the probability of the final diagnosis of the patient, value judgement in clinical decisions and costs of diagnostic examinations were considered of highest educational value, 1.5-1.6. Postgraduate clinical pathological conferences with patient demonstrations including systematic reviews of the clinical decision process are valuable in the clinical training of doctors.

Clinical Competence↗
PubMed1991

In vivo 1H-spectroscopy of human intracranial tumors at 1.5 tesla. Preliminary experience at a clinical installation.

Magnetic resonance spectroscopy (MRS) may contribute to the characterization of intracranial tumors in vivo. Volume selective water suppressed proton spectroscopy offers the possibility to study a number of metabolites in the brain including choline (CHO), creatinine/phosphocreatinine (CR/PCR), N-acetylaspartate (NAA), and lactate. Using the stimulated echo technique we have studied 17 patients with intracranial tumors. In all cases the tumors were classified based on histologic evaluation. The tumor spectra differed considerably from those obtained in healthy brain tissue. The results indicate a relative decrease in the NAA and CR/PCR content. In many cases a lactate peak could be seen especially in the tumors with malignant growth characteristics. Our preliminary results suggest that proton spectroscopy may contribute to the differentiation of brain tumors with respect to benign or malignant growth. However, further research is warranted before a definite conclusion can be drawn.

Adult↗
PubMed1990

Significance of predominantly irritative symptomatology before a prostatic operation.

The prognostic value of an excess of preoperative irritative symptoms of prostatism was evaluated. The prospective study included 139 men treated for benign prostatic hyperplasia who were evaluated by symptom analysis, uroflowmetry, water cystometry and pressure-flow study preoperatively and 6 months postoperatively. The criterion for evaluation of postoperative success or failure was the subjective evaluation of the patient at 6 months. None of the single preoperative symptoms of prostatism predicted an eventual postoperative failure, nor did the preoperative predominance of irritative symptoms or the combination of irritative symptoms and detrusor instability attain prognostic significance.

Humans↗
PubMed1990

Urodynamic implications of benign prostatic hyperplasia.

By the age of 60, about 70% of men have developed benign prostatic hyperplasia (BPH), and 85%-95% of these have symptomatic dysfunction of the lower urinary tract, 10%-20% undergoing prostatectomy. Although transurethral resection of the prostate is generally considered to be a safe and effective surgical procedure, it has recently been shown that immediate surgery, as opposed to a wait-and-see strategy, leads to a 1-month reduction in life expectancy. In 10%-15% of the patients who undergo surgery, the postoperative result is unsatisfactory as symptoms persist. Between 4% and 40% of patients undergoing prostatectomy become impotent. A urodynamic study with a scope extending beyond that of the standard urological examination is therefore needed to help reduce the number of treatment failures. The value of preoperative cystometry is questionable, since preoperative documentation of detrusor instability has no bearing on the postoperative result. Measurement of urinary flow, in contrast, is of predictive value in BPH, patients in whom the maximum urinary flow before surgery is more than 15 ml/s having significantly worse results of surgery than those with a maximum urinary flow of less than 15 ml/s before surgery. Further data relevant to the prognosis are yielded by pressure-flow investigations, which allow a quantitative estimate of the degree of obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1990

In vivo 1H spectroscopy of the human brain at 1.5 tesla. Preliminary experience at a clinical installation.

In vivo localized water suppressed proton spectroscopy of human brain was carried out on 15 healthy volunteers and 2 patients suffering from a brain tumour and an infarction, respectively. The measurements were performed on a whole body MR system, operating at 1.5 tesla using the stimulated echo technique. Our preliminary results indicate that it is possible to detect a number of metabolites in the brain within a total measurement time of one hour. The dominant peaks in the spectra from healthy volunteers are N-acetyl aspartate, choline and creatine/phosphocreatine. The spectra obtained from the brain tumour and the infarct, respectively, differed very much from those obtained in healthy brain tissue. Our preliminary results indicate that localized proton spectroscopy may contribute to non-invasive brain tumour classification and possibly also to the differentiation between tumours and infarcts in clinically doubtful cases.

Adult↗
PubMed1988

Urodynamics in prostatism. I. Prognostic value of uroflowmetry.

A prospective study was undertaken to examine the prognostic value for the symptomatic outcome of prostatic surgery of preoperative urodynamic testing in patients with prostatism. The study design included selection of patients for prostatic surgery by means of classic non-urodynamic urologic investigations such as history, residual urine, serum creatinine, cystoscopy and possibly intravenous urography. In addition an extensive urodynamic work-up (uroflowmetry, cystometry and pressure-flow study with stop-test) was included. The results of the urodynamic studies were unknown to the surgeon selecting the patients for operation. This evaluation was repeated 6 months postoperatively. Totally 139 patients entered the study. The patients were classified according to the preoperative maximum flow rate (Qmax) and in spite of preoperative differences in uroflow, pressure-flow variables and symptom scores, no differences of clinical significance were noted postoperatively among the groups. However, the high-flow group (preoperative Qmax greater than or equal to 15 ml/sec) had a statistically significant lower success rate as judged by the patients subjective evaluation of the outcome of surgery. An analysis of diagnostic sensitivity and specificity indicated Qmax = 15 ml/sec as a relevant cut-off value regarding preoperative identification of patients at risk of a less favourable outcome of surgery. This group of patients was characterized by a higher incidence of persistent uninhibited detrusor contractions at follow-up and a lower incidence of preoperative infravesical obstruction. In conclusion we recommend uroflowmetry in the preoperative evaluation of patients with prostatism.

Aged↗
PubMed1988

Urodynamics in prostatism. I. Prognostic value of uroflowmetry.

A prospective study was undertaken to examine the prognostic value for the symptomatic outcome of prostatic surgery of preoperative urodynamic testing in patients with prostatism. The study design included selection of patients for prostatic surgery by means of classic non-urodynamic urologic investigations such as history, residual urine, serum creatinine, cystoscopy and possibly intravenous urography. In addition an extensive urodynamic work-up (uroflowmetry, cystometry and pressure-flow study with stop-test) was included. The results of the urodynamic studies were unknown to the surgeon selecting the patients for operation. This evaluation was repeated 6 months postoperatively. Totally 139 patients entered the study. The patients were classified according to the preoperative maximum flow rate (Qmax) and in spite of preoperative differences in uroflow, pressure-flow variables and symptom scores, no differences of clinical significance were noted postoperatively among the groups. However, the high-flow group (preoperative Qmax greater than or equal to 15 ml/sec) had a statistically significant lower success rate as judged by the patients subjective evaluation of the outcome of surgery. An analysis of diagnostic sensitivity and specificity indicated Qmax = 15 ml/sec as a relevant cut-off value regarding preoperative identification of patients at risk of a less favourable outcome of surgery. This group of patients was characterised by a higher incidence of persistent uninhibited detrusor contractions at follow-up and a lower incidence of preoperative infravesical obstruction. In conclusion we recommend uroflowmetry in the preoperative evaluation of patients with prostatism.

Adult↗
PubMed1988

Urodynamics in prostatism. II. Prognostic value of pressure-flow study combined with stop-flow test.

In a prospective study the prognostic value of preoperative pressure-flow studies in prostatism was examined. The indications for prostatectomy were based on non-urodynamic data only. An extensive urodynamic evaluation was performed pre- and postoperatively, including uroflowmetry, water cystometry and pressure-flow study combined with stop-flow test. In total the data from 130 patients were considered. The material was classified with respect to the "urethral resistance relation" (URR) and the "bladder output relation" (BOR). According to the first criterion 87 patients were obstructed, 36 unobstructed, while 7 were unclassifiable and finally excluded. In most urodynamic variables, the two groups differed preoperatively, but no differences were revealed postoperatively. However, the obstructed group did considerably better postoperatively as to the symptomatic outcome. The success rate was 93% as opposed to 78% in the unobstructed patients (p less than 0.02). For the BOR classification, the theoretical maximum flow rate (Qm,est) was employed forming two groups: 57 patients with decreased bladder speed (Qm,est less than 35 ml/sec) and 41 patients with normal speed (Qm,est greater than or equal to 35 ml/sec). Few differences in urodynamic variables were found both pre- and postoperatively, but no significant difference was shown in success rates. In conclusion the URR proved a significant prognostic value in prostatism and is recommended in the preoperative work-up, especially in patients with equivocal uroflow studies. No convincing prognostic role could be attributed to the BOR.

Adult↗
PubMed1988

Urodynamics in prostatism. III. Prognostic value of medium-fill water cystometry.

The influence of preoperative cystometric findings on the post-surgical outcome in prostatism was examined in a prospective study comprising 139 consecutive patients. A blinded study design was used, including an entirely non-urodynamic selection procedure for prostatic surgery. In addition an extensive urodynamic investigation was carried out including: spontaneous uroflowmetry, medium-fill water cystometry and pressure-flow study combined with stop-flow test. All patients were re-evaluated 6 months postoperatively, both symptomatologically and urodynamically. The patients were classified in three groups according to the preoperative detrusor function: normal, overactive in the standing position and overactive in the supine position. No significant urodynamic nor symptomatologic differences were shown, neither pre- nor postoperatively. Nor did the subjective outcome differ between the groups. Demonstration of postoperative (persistent) detrusor instability was associated with an unfavourable subjective outcome. While residual urine had no predictive importance, a preoperative maximum cystometric capacity less than 300 ml appeared to indicate postoperative failure. Significant association was found between urge and detrusor instability. In conclusion, cystometry is not worthwhile in the preoperative work-up in prostatism.

Adult↗
PubMed1988

Urodynamics in prostatism. IV. Search for prognostic patterns as evaluated by linear discriminant analysis.

In order to examine the prognostic role of routine urodynamic testing in prostatism, a prospective study was undertaken. The patients were selected for prostatic surgery exclusively by means of non-urodynamic criteria, but in addition an extensive, blinded urodynamic work-up was performed, including uroflowmetry, pressure-flow study combined with stop-flow test and water cystometry. The study comprised 139 patients consecutively referred for prostatism. Six months postoperatively all patients were reexamined. Previously the preoperative urodynamic data from each modality were analysed separately. In an attempt to increase the prognostic information, all data were computed simultaneously using linear discriminant analysis. Several preoperative variables appeared valuable to discriminate between patients with favourable and unfavourable postoperative outcome, respectively. However, the results of classification employing even the best combinations of variables did not result in more than 88% of the patients being correctly classified. Furthermore, especially the patients with unfavourable outcome generally were misclassified. Several reasons for this lack of efficacy are briefly mentioned, including the great overlap in preoperative urodynamic data between patients with favourable and unfavourable postoperative outcome and the relatively low postoperative failure rate.

Adult↗
PubMed1987

Relationship between urinary flow curve patterns and symptomatology in elderly males.

In a random sample of elderly males prostatic type flow curves constituted slightly more than 50%, but no differences were proven comparing persons with and without prostatism. Also no clinically significant relationships between symptoms of lower urinary tract dysfunction and the various flow curve patterns were established. A hypothesis is advanced concerning the sequence of flow curve changes in elderly males, from normal bell-shaped curves to prostatic and finally irregular types, reflecting prostatic hyperplasia with gradual detrusor decompensation.

Aged↗
PubMed1986

Is there need for both intravenous urography and voiding cystography in the evaluation of children with recurrent urinary tract infections?

In a prospective study 33 children (aged 6-14 years) consecutively referred for recurrent urinary tract infections (RUTI), underwent intravenous urography (IVU) as well as voiding cystography (VC). Seven children had unilateral and two children had bilateral renal scarring, while ten children had unilateral and six children had bilateral vesico-ureteral reflux (VUR). Following normal IVU VUR was demonstrated in 22% of the ureters, but in all cases of low grade. In abnormal IVU, i.e. renal scarring or dilatation of the ureters, VC showed high grade VUR in 54% of the ureters. Based on these results and the current theories on the significance of patient age and grade of VUR, we conclude that in case of a normal IVU in children with RUTI and age of at least 6 years, there is no reason to supplement the pre-treatment evaluation with VC.

Adolescent↗
PubMed1986

Predictive value of low maximum flow rate in benign prostatic hyperplasia.

Among 84 patients with prostatism selected for transurethral resection of the prostate, 18 had a maximum flow at spontaneous uroflowmetry less than or equal to 7 ml/sec. Preoperatively there was no significant difference between patients with maximum flow less than or equal to 7 ml/sec (Group 1) and patients with maximum flow greater than 7 ml/sec (Group 2) in age, duration of symptoms, symptom scores, bladder volume, residual urine, and detrusor pressure at maximum flow. Patients in Group 1, however, had significantly lower urethral resistance and bladder volume independent maximum flow than patients in Group 2. Postoperatively, patients with preoperative maximum flow less than or equal to 7 ml/sec improved significantly in symptom scores and urodynamic findings apart from bladder volume and detrusor pressure at maximum flow. There were no significant differences between groups in postoperative symptom scores or urodynamic findings. We conclude that preoperative maximum flow rates less than or equal to 7 ml/sec at spontaneous uroflowmetry were related to high urethral resistance and not detrusor decompensation among patients with prostatism, and that patients with maximum flow rates less than or equal to 7 ml/sec fared as well postoperatively as patients with maximum flow greater than 7 ml/sec.

Aged↗
PubMed1986

Uroflowmetry in asymptomatic elderly males.

Uroflowmetry is important in the evaluation of prostatism. We have investigated 93 men, selected at random from the National Register, who had no subjective voiding problems but who fell within the appropriate age range. The sample was representative of the male metropolitan population. Uroflowmetry was carried out and the data are presented graphically in nomograms where the Q max/volume, Q average/volume and Q max time/volume relations are given. Flow variables were evaluated to delineate possible correlations to age. It was found that the median Q max decreased from 18.5 ml/s at the age of 50 years to 6.5 ml/s at 80 years. Only one-third of the group had a Q max exceeding 15 ml/s. The median voided volume was 208 ml. Half of the subjects voided less than 200 ml and one-third less than 150 ml.

Age Factors↗