METHOD AND DEVICE FOR ASSESSING THE STATUS OF THE PELVIC FLOOR MUSCULATURE OF A PATIENT

Abstract: A catheter is introduced into a body opening in the patient's pelvic region and is retained in the body opening. The force which is transmitted to the catheter at squeezing and straining, respectively, via the bounding wall of the body opening respectively, is transmitted mechanically by means of the catheter to a measuring site provided externally of the patient's body for indication of the force. The catheter is connected with a force sensor (24) which is supported by a support means (14) in a fixed position in relation to a standing accommodation (35) for the patient. A force indicator (32) is operatively connected with the force sensor.

Description: Title of the Invention: Method and device for assessing the status of the pelvic floor musculature of a patient The invention relates to method and device for assessing the status of the pelvic floor musculature of a patient in connection with incontinence evaluation or for another purpose . The meaning of urinary incontinence is a person's inability to keep back the urine, which means that repeated involuntary urine passages occur. It is distinguished between two main types of urinary incontinence, urge incontinence and stress incontinence. Urge incontinence is considered to be caused above all by uncontrolled contractions of the bladder during the filling thereof. At stress incontinence urine leakage arises in connection with increased abdominal pressure which occurs at laughing, straining, coughing, lifting, jumping, and other physical activities. Stress incontinence affects principally middle- aged women with whom the symptoms rather often make their debut in connection with a childbirth. Epidemiological studies have shown that about 10 % of the adult population suffers of urinary incontinence of varying degree of severity. This corresponds to about 480 000 individuals in Sweden only. 60 % thereof are stress incontinent women. The total outlay of the Swedish society for urinary incontinence was estimated to 3 billions SEK in the money value of 1996, corresponding to about 2 % of the total medical expense. Merely the expense for free aids (substantially napkins) to urinary incontinent persons during the same year exceeded 1.5 billions SEK. Urge incontinence generally is treated pharmacologically. On the basis of neurophysiological studies also electrical stimulation has been developed to be an alternative course of treatment for this type of incontinence. Electrical stimulation has also been tested for treating stress incontinence. However, the traditional treatment of stress incontinence generally comprises surgical reconstruction or physiotherapeutic training of the pelvic floor. The surgical treatment provides permanent continence of 60 to 80 % of the patients depending on the method. Many patients with unsatisfactory result after training of the pelvic floor are cured after a surgical operation. Unfortunately, there are at present no diagnostic methods for assigning the individual patient to the optimal treatment method, physiotherapy or surgery. Principally stress incontinence is caused by failing closing function of urethra. As mentioned above the problem arises with women most often in connection with a childbirth. The pathophysiological mechanisms are still unclear. Overstretching injuries on pelvic floor structures such as muscles and ligaments (which function as passive suspension and attachment means for bladder, uterus, and rectum) are suggested to be one reason. There are also indications of the function failure being due to a peripheral nerve injury. A correct identification of the primary cause will influence the choice of therapy. If the incontinence is caused by a ligament injury it can hardly be expected that physiotherapy can improve the condition. In this case surgical reconstruction must be optimal treatment. When the muscle function is bad physiotherapy combined with newly developed surgical treatment methods can complement each other. The functional evaluation of the pelvic floor usually is made by a physiotherapist or urotherapist . Several methods have been used in order to estimate the condition of the pelvic floor musculature. One method is to subjectively estimate the squeezing ability of the patient by manual vaginal palpation. Another method is to measure the patient's ability to carry conical weights in vagina, cf . e.g. US-A-4 895 363 and US-A-5 213 557. It has also been tried to quantify the squeezing force in the pelvic floor by means of air or liquid filled balloons in urethra, rectum or vagina, cf . e.g. GB-A-2 187 959,EP-Al-0 219 410, and WO-A1-93/17619. These pressure measuring methods are connected with a fundamental problem. A pressure increase is observed both at squeezing movement in the pelvic floor and at the antagonistic movement thereof, straining (due to pressure transmission from the abdominal cavity) . Thus, it cannot be decided on the basis of the measuring result if the patient squeezes or strains. What is worse all individuals generate an increased abdominal pressure at maximal squeezing movements (due to simultaneous contraction of the diaphragm and the muscles of the abdominal wall. Even if it can be guaranteed that the patient in fact squeezes the registered pressure comprises two components, the actual squeezing pressure and an unknown transmission pressure from the abdominal cavity. This measuring method thus cannot be used when it is the question of quantitatively estimate the pelvic floor function. This is true also in case the evaluation of the status of the pelvic floor musculature is effected by using a catheter which is introduced into vagina or rectum and is provided with electrodes for measuring myographic signals from the pelvic floor musculature, cf . for example US-A-5 154 177 and US-A-5 452 719. There is no simple relation between amplitude of these myographic signals and muscle force of different individuals. The purpose of the invention is to provide method and device of the kind referred to above, eliminating the drawbacks of prior art methods and devices accounted for above. Then, one focuses on the upward force of parts of the pelvic floor musculature at squeezing and on the downward force at straining. The pelvic floor is in fact shaped as an open cone with muscles which surround urethra, vagina, and rectum and extend upwards and outwards to the attachment at the pelvic bone. The anatomic extension of the muscles causes lifting of these organs at an active contraction (squeezing movement) , and this obligatory lifting movement is now utilized in order to effect an objective, quantitative estimation of the pelvic floor function by measuring the depression force (downward force) exerted by the abdominal pressure on the pelvic floor at straining and providing a measure of the need of muscular carrying capacity, as well as the lifting force (upward force) exerted by the pelvic floor musculature at squeezing and indicating the power of the musculature in order that one will be able to choose the optimal treatment method for incontinence by guidance of the measuring result obtained thereby. In order to achieve said purpose the method of the invention has been given the characterizing features of claim 1 and the device proposed according to the invention for working the method has been given the characterizing features of claim 5. In order to explain the invention in more detail an illustrative embodiment of the device and the use thereof when applying the method of the invention will be described below reference being made to the accompanying drawings in which, FIG. 1 is a side view of the device and illustrates diagrammatically the use thereof, FIG. 2 is a side view of an expendable set included in the device, and FIG. 3 is an enlarged cross-sectional view along line III-III in FIG. 1. On a wall 10 there are mounted a support rail 11 for a sacrum rest 12 and a support unit 13 for a support arm 14. Support arm 14 is adjustable vertically by means of a servo motor in unit 13, and the adjustment is controlled from a control unit 15. Support arm 14 is attached to unit 13 at 16, and this attachment can be of a type allowing support arm 14 to be swung to different positions but the support arm can also be mounted in a fixed position. In the outer free end of support arm 14 there is means 17 for attaching a yoke 18 having a stem 19. Stem 19 can be inserted into a slot 20 in a head 21, FIG. 3, and can be fixed in the slot by means of a clamp screw 22. Head 21 can be rotated to different positions on support arm 14. A pressure sensor 24 is mounted between the limbs of the yoke, said sensor comprising an elastically stretchable resistance element the electric resistance of which is altered by stretching of the resistance element. A catheter with an expandable restrainer shown here as a balloon 25 which may be coated with an antiglidant and has a tubular stem 26 is mounted at said stem in sensor 24 and is connected by a hose 27 to an air pump 28 by means of which balloon 25 can be inflated. By means of a wire 29 and a contact pin 30 sensor 24 can be connected to a contact socket 31 on support arm 14 in order to be connected with electronic means in support unit 13 via electric wiring in support arm 14 signals from the electronic means being transmitted to a display 32 on control unit 15 via a wire connection 33 between support unit 13 and control unit 15. It is the intention that yoke 18 with attachment stem 19, sensor 24, balloon catheter 25, 26, and pump 28 with connection hose 27 as well as wire 29 with pin 30 shall be included in an expendable set, FIG. 2, which includes also a pair of scissors 34 or a scalpel. A floor 35 forms adjacent wall 10 a standing accommodation for a patient fragmentarily disclosed at 36 in a diagrammatic vertical cross-sectional view for whom the status of the pelvic floor musculature shall be estimated e.g. in connection with evaluation of incontinence. Using the device described and applying the method of the invention this evaluation is performed as described below. During the measuring procedure the patient shall be in upright position in order to imitate everyday situations when a stress incontinent patient typically is affected by involuntary urinary leakage. Therefore, the patient shall be standing with straight legs on floor 35 straddling support arm 14 which is adjusted by means of support and control unit 13 to a position vertically, which is adapted to the size of the patient. Also the position vertically of sacrum rest 12 is adapted to the size of the patient. Yoke 18 is fixed in a suitable displaced and angular position on support arm 14 by means of attachment means 17 (FIG. 3) in order that balloon catheter 25, 26 can be inserted into vagina. By means of pump 28 balloon 25 is inflated inside vagina and then one pulls gently in the catheter in distal direction until the patient registers a retention of the catheter in vagina. Yoke 18 is now adjusted in such a way that the sensor with the catheter in said position has some bias (for example 0.5 N) , and the indication on display 32 is zeroed at said bias. As a consequence thereof squeeze movements of the patient will generate positive measure values in N of the force generated at the squeeze movement while straining will generate corresponding negative measure values. When the method according to the invention is applied by using the device described there is thus obtained an unequivocal discrimination between squeeze and strain movements. Preferably, measuring is made at three maximal squeezings, strains, and coughs. The possible fatigue of the musculature can also be measured by means of one prolonged maximal squeezing. The electronic means in the support unit 13 can be connected not only to control unit 15 with display 32 but also to a printer for presentation of the patient's momentary squeeze/strain parameters for positive and negative maximal values and analogue registration of a complete sequence at squeezing, straining, and coughing. A minor pilot study including continent and stress incontinent women has shown that the method according to the invention has a good reproductivity. The variability of the measuring procedure is equivalent to or less than the ability of the individual patient to generate actively repeated maximal squeeze movements of the same amplitude. This variability in turn can be neglected in relation to the interindividual difference in pelvis floor power (which varies with a factor of 6) . In the pilot series the stress incontinent women had a definitely lower relative lifting power than the continent women, i.e. lower muscle power in relation to the individual need of active contraction ability. The difference was particularly pronounced at coughing, the situation when the majority of stress incontinent women leak. A more detailed analysis disclosed that the incontinent women could be separated into two distinct groups. Patients in one group had greatly weakened passive suspension means (ligament) for the pelvic floor and as a consequence thereof an unreasonably large power deficit. This patient group quite likely must be treated by reconstructive surgery in order to be continent. The other patient group had rather well preserved passive functions and could be expected to gain a normalized function by means of pelvic floor training or electro-stimulation. The demonstrated difference in pelvic floor function is of great clinical importance if these preliminary observations can be confirmed because said difference implies that the method of the invention can be used in order to determine optimal treatment strategy for the individual patient. Such a clinical method of selection involves great savings both for the medical service and for the individual patient. The pilot study referred to above indicates that the actual measuring method functions as expected: it distinguishes unequivocally between squeeze and strain movements of the pelvic floor, provides reproducible quantitative measure values in easily comprehensible units, and can be used to choosing an optimal treatment procedure at stress incontinence. When the measurement has been performed hose 27 is cut by means of the pair of scissors 34 in order that the air shall leave balloon 25 so that the balloon catheter can be withdrawn from vagina. The device described for working the method of the invention can be modified as far as the constructive details are concerned. Another type of pressure sensor can be provided, for example a strain gauge on a flexible element which is connected with the balloon catheter and is bent in one direction or the other at squeezing or straining, respectively. The balloon catheter can be replaced by another type of catheter which is shaped in order to be retained in vagina. Instead of inserting the catheter into vagina it can be inserted into another body opening in the pelvic region also of men, viz. rectum or urethra. In that case the catheter must of course be constructed in order to be fit for the actual body opening. In order to further increase the possibility of adapting the device to the size of the patient support arm 14 can be made telescopic.

Claims: CLAIMS 1. Method for assessing the status of the pelvic floor musculature of a patient, characterized in that a catheter is introduced into a body opening in the pelvic region of the patient and is retained in the body opening, and that force transferred to the catheter at squeezing and straining, respectively, via the bounding wall of the body opening is transmitted mechanically by means of the catheter to a measuring site provided externally of the patient's body for indication of the force. 2. Method according to claim 1, characterized in that the patient is standing over said measuring site. 3. Method according to claim 1 or 2 , characterized in that the force transmitted to the measuring site is made to actuate a force sensitive transducer for transforming the force to a signal that can be measured, preferably an electric signal. 4. Method according to claim 3, characterized in that a predetermined tensile force is applied to the catheter when it is introduced into the body opening and is unaffected by squeeze and strain forces, and that measuring equipment used for the measurement is zeroed at said predetermined tensile force. 5. Device for assessing the status of the pelvic floor musculature of a patient, characterized by a catheter (25, 26) to be introduced and retained in a body opening in the pelvic region, a force sensor (24) connected with the catheter, means (14) for supporting the force sensor in a fixed position in relation to a standing accommodation (35) for the patient, and a force indicator (32) operatively connected with the force sensor. 6. Device according to claim 5, characterized in that said means (14) for supporting the force sensor (24) can be adjusted to different levels and be retained in the desired adjusted position. 7. Device according to claim 6, characterized in that said means (14) for supporting the force sensor (24) comprises a pivoted arm. 8. Device according to any of claims 5 to 7 , characterized in that a sacrum rest (12) is provided at the standing accommodation and is fixed in relation to the standing accommodation. 9. Device according to any of claims 5 to 8 , characterized in that the catheter (25, 26) and the force sensor (24) are made as an expendable product. 10. Device according to claim 9, characterized in that said means (14) for supporting the force sensor is arranged for demountable connection of the expendable product therewith. 11. Device according to any of claims 5 to 10, characterized in that the catheter (25, 26) comprises a balloon catheter which is retained by inflation in the body opening after introduction therein by inflation. 12. Device according to any of claim 5 to 11, characterized in that the force sensor comprises a resistance element (24) which is connected at the ends thereof the resistance of said element being dependent of the stretched condition of the element. 13. Device according to claim 12, characterized in that the catheter (25, 26) is connected with the resistance element (24) between the ends thereof. 14. Device according to claim 13, characterized in that the resistance element (24) is connected between the limbs of a yoke (18) which is included in the expendable product and can be connected with the support arm (14) . 15. Device according to any of claims 11 to 14, characterized in that an air pump (28) included in the expendable product is connected to the catheter.

Inventors: CLAREN JAN, LINDSTROEM SIVERT, OHLSSON BO, CLAREN, JAN, LINDSTROEM, SIVERT, OHLSSON, BO
Applicants: CLAREN JAN, LINDSTROEM SIVERT, MEDSCAND MEDICAL AB, OHLSSON BO, CLAREN, JAN, LINDSTROEM, SIVERT, OHLSSON, BO
Application year: 1999
Main classification: A61B5
IPC codes: A61B5, A61B10, A63B23