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Biomedical subjects

P Glemain

Publications and source records attributed to P Glemain.

At least 19 recordsLinked to original sources
PubMed2005

A simple method to optimize hospital beds capacity.

OBJECTIVE: The number of acute hospital beds is determined by health authorities using methods based on ratios and/or target bed occupancy rates. These methods fail to consider the variability in hospitalization demands over time. On the other hand, the implementation of sophisticated models requires the decision concerning the number of beds to be made by an expert. Our aim is to develop a new method that is as simple to use as the ratio method while minimizing the roundabout approaches of these methods. METHOD: A score was constructed with three parameters: number of transfers due to lack of space, number of days with no possibility for S unscheduled admissions and number of days with at least a threshold of U unoccupied beds. The optimal number of beds is the number for which both the mean and the standard deviation of the score reach their minimum. We applied this method to two internal medicine departments and one urological surgery department and we compared the solutions proposed by this method with those put forward by the ratio method. RESULTS: The solutions proposed by this method were intermediate to those calculated by the local and national length of Stays ratio methods. Simulating an unusual increase in admission requests had no consequence on the bed number selected, indicating that the method was robust. CONCLUSION: Our tool represents a real alternative to the ratio methods. A software has been developed and is now available for use.

Algorithms↗
PubMed2003

Clinical and urodynamic repercussions after TVT procedure and how to diminish patient complaints.

OBJECTIVES: Analysis of changes in voiding patterns after sub-urethral TVT procedure: urodynamic variations and clinical repercussions. METHODS: 112 women included in an ethics committee protocol (CCPPRB ) with a mean follow-up of 22 months underwent complete urodynamic testing before and after TVT procedure and filled in pre- and post-operative questionnaires. RESULTS: Analysis of the questionnaires showed that two clinical symptoms were predominant post-operatively: dysuria and micturitional urge. The urodynamic profiles showed that TVT banding led to infravesical obstruction but not to significant detrusor overactivity. CONCLUSION: Our results show that clinical changes induced by the TVT procedure were due to infravesical obstruction, and that there was no progression of detrusor overactivity. We suggest two ways to avoid, or diminish, this post-operative obstruction, or to detect patients at risk from obstruction: training for women who use their abdominal muscles for voiding rather than their detrusor, or pre-operative screening of hypotonic bladders.

Adult↗
PubMed2001

[Dangers of sub-group analysis and of multiple tests].

Subgroup analyses, "retrospective" statistics, and multiple tests, motivated by the search for explanatory covariables, are frequently used in the medical literature. However, these data manipulations induce modifications of the groups defined by initial randomization, an unverifiable increase of the alpha risk, a reduction of the power of the study and a risk of circular reasoning. Taking the example of an article concerning the hormonal treatment of prostate cancer, several situations are discussed, according to whether or not the study is prospective, whether or not the covariables are defined from the outset, and whether or not the results for the primary endpoint are significant.

Humans↗
PubMed2001

[Accuracy of pressure measurements obtained with a new rectal balloon catheter].

UNLABELLED: The accuracy of measurements performed by a balloon catheter used to record abdominal pressure during urodynamic investigations was verified on a test bench. OBJECTIVE: To study the accuracy and precision of the pressure measurements obtained with a new rectal balloon catheter (ref. 95018 Laboratoires Vermed), designed to record abdominal pressure during urodynamic assessments. The clinical value of this catheter, using air for pressure transmission, is its simplicity, as there is no contamination of the perfusion circuit or transducer, no purging of the circuit, and artefacts related to movements of the tubing are eliminated. METHOD: The catheter was placed in a pressure chamber fitted with a precise, calibrated regulation system allowing programmed pressure variations from 10 to 150 cmH2O. Pressures recorded by the test catheter were compared to reference pressures applied to the chamber. The frequency of acquisition of pressure measurements was 100 Hertz and the resolution was 10 Hertz. This model was used to study the accuracy of pressure measurements and the response times of the catheter. Measurements were performed with a volume of 2 ml of air introduced into the catheter (volume recommended by the manufacturer), and the optimal volume was investigated by inflating the catheter until the best result was obtained. The evaluation was based on calculation of the mean difference observed between the two measurements and the scatter of the differences observed. RESULTS: When the catheter was filled with 2 ml of air, pressures measured by the catheter were overestimated an average of 1.1 cmH2O (standard deviation = 1), and 95% of the differences between the two measurements were within +/- 2.15 cmH2O. The optimal air volume was found to be 1.5 ml. With this air volume, no significant difference was observed between the two measurements. The mean observed difference was 0.2 cmH2O (SD = 1.2), which means that 95% of the differences were situated within the range of +/- 2.35 cmH2O. CONCLUSION: The pressure recording method with this new catheter is validated in terms of physical parameters.

Equipment Design↗
PubMed2001

[A necessary number or subjects... to conclude].

The fact that a difference is not statistically significant does not mean that it does not exist. Some differences are not demonstrated by studies conducted on small sample sizes due to random sampling fluctuations. To demonstrate a difference which really exists or to conclude on the absence of a difference, the study must have a sufficient power, essentially determined by the number of subjects included. In the case of comparisons of survival curves, the number of events or total deaths at the time of analysis determines the power of the study. Examples derived from the urological or theoretical literature will illustrate the value of calculating the number of subjects required before starting the study and the value of retrospectively evaluating the power of a study in order to interpret its results.

Clinical Trials as Topic↗
PubMed2000

[The causal relationship].

Only the controlled trial method, clinical equivalent to the experimental method, with its successive phases and randomization, is able to confirm a real causal relationship and quantify the risk of error (alpha). However, the study must have sufficient power and randomization must not have resulted in an unbalanced distribution of various parameters likely to influence the result. Other methods, particularly surveys and case studies, only provide presumptions of causality. This review article, illustrated by three examples from the urological literature, is designed to demonstrate the difficulties of establishing a causal relationship when possible biases and confounding factors are taken into account.

Causality↗
PubMed2000

[Intent to treat].

Intent to treat methodology consists of keeping all patients included, in their initial group in the case of randomization, to perform final analysis of a study. This attitude is justified methodologically, as it preserves the validity of the statistical rationale, and clinically, as it more closely reproduces real prescribing conditions. In the light of a classical example, this review illustrates several clinical situations raising the problem of intent to treat.

Clinical Trials as Topic↗
PubMed1998

Outcome of patients with an implanted artificial anal sphincter for severe faecal incontinence. A single institution report.

Implantation of an artificial sphincter is an alternative treatment for patients with severe faecal incontinence. This prospective study from one institution has evaluated the results from 13. Preoperative and postoperative incontinence scores, anal manometry, and quality of life were evaluated in 13 patients who had undergone implantation of an artificial sphincter over a 7-year period. Two patients were definitive failures. One developed acute total colitis after 5 years of satisfactory function, and a second had discomfort and demanded removal of an otherwise functioning device. After a median follow-up of 30 (range 5-76) months, 11 patients had an activated and functional device. These included 6 with a urinary AMS 800 and 5 with the newly designed anal ABS. The mean incontinence score decreased from 17 to 4, and quality of life improved markedly. Two of the 11 patients had undergone successful reimplantation, one following rupture of the cuff and the second following ulceration of the control pump through the labia. In no case was infection or erosion of the anal canal a cause of failure. While the cause of incontinence and age did not affect outcome, psychological reaction had a significant impact. The artificial anal sphincter may have a role to play in severe faecal incontinence.

Adult↗
PubMed1996

[Instantaneous pressure/flow ratio for non-permanent flows. Impact on the assessment of urethral resistance].

OBJECTIVE: To verify the validity of the hypothesis of the almost continuous flow necessary for evaluation of instantaneous urethral resistance R by the pressure/flow relation R = P/Q2. METHOD: An experimental device allowed investigation of the pressure/flow relation for discontinuous flow in a flexible tube. The tube was submitted to various collapsing pressures and opened under the effect of flow. The flow was discontinuous because of the variations of the proximal pressure or oscillations in the hydraulic diameter of the tube. RESULTS: These experiments showed that the approximation of continuous flow is justified within the limits of precision of the measuring methods used in urodynamics. CONCLUSION: The formula R = Q2 is therefore theoretically correct and validated by the experimentation. There is no hydrodynamic obstacle to the application of this formula to the calculation of instantaneous urethral resistance.

Pressure↗
PubMed1995

[Reliability of pressure measures determined with probes used for establishing the urethral pressure profile by the perfusion method].

The objective of this study was to evaluate the reliability of pressure measurements by the main catheters used to determine urethral profiles by the perfusion method. This evaluation, performed on a test bench, compared the reference pressure in a tank filled with water to that measured by the catheter tested. The reliability of the measurement varied from one catheter to another. This disparity was due to differences of load losses, leading to an overestimation of the measurement (by 2 to 17 centimetres of water), which must be corrected by adjustment of the zero pressure with a perfused catheter. Major differences in the rapidity of response (from zero to five seconds) were also observed, which appear to be related to elastic properties of the catheter. This study does not pretend to globally verify the reliability of the perfusion method, but only the reliability of pressure measurements.

Perfusion↗
PubMed1993

Nonsurgical treatment evaluation in benign prostatic hyperplasia patients.

The development of new methods for treating benign prostatic hyperplasia (BPH) requires the choice of reliable criteria in order to assess their efficiency. It is, first of all, necessary to choose clinical as well as urodynamic criteria. Clinical criteria must be quantified and then gathered in scores, so that they can be compared. These changes, essential to the statistician, alter the true meaning of symptoms. The value of urodynamic parameters to 'measure' obstruction differs widely: the pressure/flow relationship as well as micturitional bladder pressure are probably the most reliable. Statistical data processing for both qualitative and quantitative variables, is still likely to alter the true meaning of these variables. This article takes a critical approach to all these problems, and also focuses on the real aim of the BPH treatment, which above all is to restore comfortable functional balance but not necessarily urodynamic performance.

Clinical Protocols↗
PubMed1993

New urodynamic model to explain micturition disorders in benign prostatic hyperplasia patients. Pressure-flow relationships in collapsable tubes, hydraulic analysis of the urethra and evaluation of urethral resistance.

How can the hydrodynamic disorders caused by benign prostatic hyperplasia (BPH) be explained? And how can they be measured in order to assess the efficiency of treatment? To answer these questions, a model based on the results of experiments performed in collapsable tubes and on a hydraulic analysis of the urethra is elaborated. A BPH combining hypertonia and/or hypertrophy, essentially leads to a rise in the opening pressure which increases bladder work before micturition, as well as a reduction in the functional caliber of the prostatic urethra. Whatever its origin, this reduction in caliber is the only explanation for the importance of the urethral resistance increase noticed in cases of BPH. Instantaneous resistance calculation, based on the pressure/maximum flow rate relationship, measured when the flow is steady (for a few seconds), would be a good experimental physical parameter. However, on a clinical basis, an exact calculation is impossible, which makes its precision and reliability not as good as they should be. In order to calculate the resistance to micturition as a whole, particularly taking into account the difficulty in urethral opening, it was suggested to include the opening pressure in the pressure/flow study. But this fits neither with fluid mechanics data nor with the results of experiments carried out in collapsable tubes. Eventually, considering that no evaluation method of the resistance to urinary flow is acknowledged to be accurate on a hydraulic basis or urodynamically applicable, one wonders whether placing more confidence in simple data obtained in a noninvasive way, and used without mathematical tricks, is not preferable.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1991

[Achieving urinary continence].

Development of urinary continence, which is necessary for species survival and comfort of human being, begins with the organization of vesico-sphincteric automatism, as part of nervous system growth. Micturitional reflex are successively integrated inside the ganglionic plexuses in the foetus, the sacral spinal cord in the newborn and the pontine center in the child. Voluntary control of this automatism needs, at first, feeling an sensitive information about the bladder fullness, that is to say a "desire of urinate". Child first controls his striated sphincter, what makes him able to avoid urine leakage and enlarges his bladder capacity. Latter, he can initiate or refuse, voluntarily, bladder contraction, doing his bladder the most intelligent organ and, consequently, the most psychologically vulnerable one. Timing of these different steps is variable; in addition to the natural maturity processes which progress more or less quickly, training adds it effects, more useful for developing continence during daytime than during night-time.

Adolescent↗
PubMed1991

[Anatomical study of the infratemporal fossa].

The infratemporal fossa (ITF) is a hidden, subracranial part of the retrofacial region, which is concealed by the mandible. While its definition corresponds to bony relationships, it goes far beyond these. The classical pyramid with a lateral mandibular base and a superomedial apex, the pterygopalatine fossa, actually is a passage for the neurovascular elements it contains. It also is the hidden aspect of the manducatory apparatus, accommodating the pterygoid muscles. Besides these bony limits, the ITF has fasciomuscular boundaries formed posteriorly by the sphenomandibular ligament and the lateral insertion of the styloidian curtain on the angle of the mandible. The anterior limit, under the maxillozygomatic bones, is formed by the pterygomandibular ligament, on which spread the fibers of the buccinator muscle. The inferior limit is only theoretic and corresponds to the lower margin of the mandible. Within these limits, the ITF is connected with the mandible and the lateral manducatory muscles, the parotid gland, the peripharyngeal spaces, the submandibular region. However, it primarily is a passage into the neighboring regions with which it communicates through openings that are either endo- or exocranial, parotid, pharyngeal, nasal, orbital. Thus this fossa is one of the paths of the expansile processes that arise from the neighboring regions and invade it, being guided by the various anatomical openings we have described.

Humans↗
PubMed1990

[Urodynamic consequences of urethral stenosis. Hydrodynamic study with a theoretical model].

An urethral model was designed to assess the hydrodynamic consequences of stenosis of the bulbar urethra. This model was based on the geometric and hydrodynamic analysis of micturing urethrograms in a patient whose maximum flow rate was 24 ml/s for a bladder pressure of 40 cm of water. It corresponds to the conditions of flow observed wit maximum bladder pressure and flow rate. During this short period, the shape of the urethra is regarded as stable. Calculation took account of the characteristics of a turbulent flow of urine, of the head loss due to friction of the urine on the walls and of the head loss caused by the geometrical changes of the urethra from the neck of the bladder to the meatus. In these conditions, applying Bernouilli's equation allowed plotting of bladder pressure for various levels of urethral resistance. If there is no stenosis, the theoretical maximum flow rate of the model with a bladder pressure of 40 to 80 cm of water should be 19 to 26 ml/s. Calculation showed that a sudden reduction of the diameter to less than 2.5 mm occurring in a segment of the urethra with a diameter of 4 mm accounts for a flox rate lower than 15 ml/s, except when bladder pressure can exceed 100 cm of water. The decrease in the maximum flow rate caused by urethral stenosis is all the greater as bladder pressure remains low or normal, with other causes of head loss or with associated upstream dilatation. Lastly, progressive narrowing leads to a smaller head loss and will therefore be better tolerated than sudden narrowing to the same caliber. Inversely, a long stenosis will be less well tolerated as the head loss due to friction in a long and narrow passage is increased. The diameter of a stenosis accounting for a maximum flow rate of less than 15 ml/s cannot be determined in the absolute. Analyzing the hydrodynamic consequences of stenosis also requires knowing the associated urodynamic and geometric parameters.

Adult↗