Biomedical subjects

S St Clair Carter

Publications and source records attributed to S St Clair Carter.

4 recordsLinked to original sources

PubMed2001

A probability based system for combining simple office parameters as a predictor of bladder outflow obstruction.

PURPOSE: We explored the relationships of office assessment of lower urinary tract symptoms, transrectal ultrasound measurement and the bladder outlet obstruction index, as derived from pressure flow studies. We also developed and validated a multivariate analysis for predicting the bladder outlet obstruction index. MATERIALS AND METHODS: We evaluated 384 men with lower urinary tract symptoms using the International Prostate Symptom Score, maximum urine flow, post-void residual urine, transrectal ultrasound and urodynamic studies. Data were analyzed by multiple linear regression with continuous variables. A simple algorithm, that is the predicted bladder outlet obstruction index, was created using the best fit variables identified from a derivation set and assessed in a separate validation set. The predicted index was applied to predict the probability of actual obstruction according to office parameters. RESULTS: Maximum urine flow and total prostate volume predicted the bladder outlet obstruction index most completely (adjusted R2 = 0.50, F 75.9, p <0.0001), while other variables were not helpful. These variables were used to create the predicted bladder outlet obstruction index algorithm, antilog10 (2.21 - 0.50 log maximum urine flow + 0.18 log total prostate volume) - 50. In the 42% of patients with a predicted index of greater than 40 there was a 92% risk or positive predictive value of equivocal or worse obstruction, whereas a predicted index of less than 20 in 23% indicated a 4% risk of significant obstruction. CONCLUSIONS: The bladder outlet obstruction index can be predicted from maximum urine flow and prostate volume. Development of the predicted bladder outlet obstruction index algorithm enables the mathematical prediction of obstruction from these simple measures. Using the predicted bladder outlet obstruction index clinicians can determine the risk of obstruction in individuals. In 65% of patients we predicted equivocal or worse obstruction with greater than 90% confidence.

Aged↗

PubMed1998

Is there a clinically significant change in pressure-flow study values after urethral instrumentation in patients with lower urinary tract symptoms?

OBJECTIVE: To determine the effect of urethral instrumentation on pressure-flow study values and subsequent grading of bladder outflow obstruction (BOO) in men with lower urinary tract symptoms (LUTS) using suprapubic intravesical pressure monitoring. PATIENTS AND METHODS: Seventy-two men with LUTS underwent pressure-flow study using suprapubic intravesical pressure monitoring. The urethra was then instrumented successively with a 12 F catheter and a 17 F cystoscope, and a further pressure-flow study recorded after each procedure. Standard pressure-flow variables were measured for the three recordings. The presence and degree of obstruction were determined using commonly recognized grading systems, i.e. the Abrams-Griffiths nomogram. the linear passive urethral resistance ratio (LPURR) and the urethral resistance algorithm (URA). RESULTS: There were statistically significant differences in the detrusor pressure at maximum flow and detrusor opening pressure between the uninstrumented and instrumented studies (12 F and 17 F) but no difference in peak flow rates between the groups or in the Abrams-Griffiths number or URA value between studies. Using the LPURR, there was a tendency to a lower obstruction class after urethral instrumentation, ranking as 17 F > 12 F > no instrumentation. CONCLUSIONS: The changes seen after urethral instrumentation represent no more than the biological intra-individual variation normally seen in pressure-flow studies and do not lead to a clinically significant change in obstruction class.

Adult↗

PubMed1997

Pressure-flow studies in the diagnosis of bladder outlet obstruction: a study comparing suprapubic and transurethral techniques.

OBJECTIVE: To compare suprapubic and transurethral methods of measuring intravesical pressure in a group of men undergoing investigation for lower urinary tract symptoms (LUTS), to identify which urodynamic variables are affected by the presence of an urethral catheter during the voiding phase, and consequently whether there is any change in the grading of bladder outflow obstruction (BOO) using the commonly recognised grading systems. PATIENTS AND METHODS: Thirty-five men with LUTS underwent both suprapubic and transurethral pressure-flow studies during a single session. Standard pressure flow variables were measured in all patients with both methods, enabling calculation of obstruction using the commonly used grading systems, i.e. the Abrams-Griffith number, linear passive urethral resistance ratio (LPURR) and urethral resistance algorithm (URA). RESULTS: There were statistically significant differences between the methods in the mean values of maximum flow rate and the detrusor pressure at that maximum: 60% of men were in the same LPURR class with either method. Using the transurethral method, 26% of patients increased the LPURR class by one and 6% by two classes. Using the Abrams-Griffiths nomogram, 17% moved from a classification of equivocal to obstructed and 3% from unobstructed to equivocal. Using the criterion of a value of URA > 29, 57% were obstructed using the suprapubic and 74% using the transurethral method. CONCLUSION: According to the method used, there were differences in the classification of obstruction between the suprapubic and transurethral routes; transurethral studies tended to indicate greater obstruction. The interpretation of urodynamic studies should take into account the technique used and where the route is transurethral, the smallest catheter available should be used.

Adult↗

PubMed1993

Clinical response to transurethral microwave thermotherapy is thermal dose dependent.

Transurethral microwave thermotherapy of the prostate was used to treat men with symptomatic benign prostatic hypertrophy. Three treatment protocols delivering increasing thermal doses (Prostasoft T-A > Prostasoft II > Prostasoft I) were evaluated. The results show a dose-dependent response. Histological changes induced by microwave heating were dependent on the temperature achieved in the tissue. Thermocoagulation is obtained above 45 degrees C and thermoablation above 60 degrees C. Using Prostasoft II in a long-term follow-up study, the Madsen symptom score decreased by 66% and peak flow rates increased by 41% over a period of more than 18 months. Using Prostasoft T-A (thermoablation) in 28 patients, a cavity was obtained inside the prostate without major complication. The symptoms and obstruction caused by benign prostatic hypertrophy can be treated by transurethral thermotherapy in a single, anesthesia-free 1-hour session on an ambulatory basis.

Follow-Up Studies↗