Surgery – Instruments – Means for removal of skin or material therefrom
Reexamination Certificate
2001-03-27
2004-08-10
Bennett, Henry (Department: 3743)
Surgery
Instruments
Means for removal of skin or material therefrom
C600S593000, C604S101050, C128S898000
Reexamination Certificate
active
06773452
ABSTRACT:
TECHNICAL FIELD
The present invention relates to medical devices and more particularly to a method and apparatus for measuring the compliance or distensibility of the lower esophageal sphincter (LES) for use in the diagnosis of esophageal function.
BACKGROUND OF THE INVENTION
It is well known in the art to use esophageal and nasogastric catheters having balloon cuffs to measure the pressure within the esophagus. These devices have been used by and large to study the condition of the lungs and the blood pressure in and around the heart. For these purposes, it is desirous to measure pressure acting on the walls of the esophagus. Accordingly, an elastic balloon cuff, coupled to a suitable pressure transducer via a catheter, is inflated against the esophagus and the amount of pressure resistance is measured and used for various purposes in diagnosis. An elastic balloon is used because it can be distended outwardly to contact and conform with the region of interest in the esophagus.
Physicians also examine the condition of the gastroesophageal junction and in particular the lower esophageal sphincter (LES), which is an involuntary ring-like muscle separating the esophagus from the stomach. The LES rests in a closed position to shut off the end of the esophagus, and is relaxed when in the open state. However, the LES does not have the motility to open on its own, rather it opens briefly by normal physiological function of the esophagus during excitation of the inhibitory nerves of the esophagus. This most commonly occurs during peristalsis when the LES opens to allow food to pass from the esophagus to the stomach. Contracting nerves return the LES to its normally closed position.
Studying the LES is often necessary to diagnose various esophageal maladies and disorders such as gastroesophageal reflux disease, stricture, achalasia, diffuse esophageal spasm, esophageal cancer and dysphagia. These esophageal disorders affect the motility of the LES and thereby its ability to open and close normally.
Motility disorders of the esophagus, including those associated with systemic disease such as that of the connective tissue, are normally diagnosed using manometry, a procedure whereby a pressure-measuring instrument can assess function of the esophageal body by measuring peristaltic presence, propagation and vigor, or nonperistaltic contractions, as well as that of the upper and lower esophageal sphincters by measuring resting tone, timing and completeness of relaxation, and response to exogenous stimuli. The use of manometry is especially indicated in cases where more common esophageal disorders have been excluded after a barium radiograph or endoscopy evaluation, and it is often indicated for preoperative assessment of peristaltic function prior to antireflux surgery, and for placement of devices when the location depends on functional landmarks such as the lower esophageal sphincter (LES) located at the esophageal and gastric junction.
To obtain manometry data, the clinician typically measures the pressure exerted by the LES when constricted as well as when it is relaxed. This is typically done manometrically by inserting a sleeve with pressure transducers or other pressure recording devices into a patient's LES and measuring pressure as the patient swallows. The constricted and relaxed pressures are then compared to known values for a healthy LES (approximately 15-30 mm Hg constricted and 1-5 mm Hg relaxed). An LES with abnormal pressure values is then treated with drugs or a surgical procedure. A problem is that the measured pressure values of an LES may be normal despite the existence of dysphagia with or without an esophageal dysfunction. In this case, measuring the LES pressure does not provide information helpful in making a diagnosis. An additional disadvantage of manometry measurement is that it is a highly technical procedure that requires significant knowledge and precise methodology to produce valid results. Therefore, it has tended to be used more for physiological studies rather than a diagnostic tool in endoscopic or radiographic procedures. For example, manometry alone is insufficient to diagnose compliance disorders of the LES; the compliance of a sphincter is its ability to stretch and open properly in response to pressure applied to it from within to regulate the flow or movement of liquid or solid materials therethrough. For example, an important function of the LES is to prevent reflux of stomach acid into the esophagus, which not only causes discomfort to the sufferer, but can lead to a potentially serious condition known as Barrett's Esophagus. The ability to determine the degree of LES compliance is especially important during surgical procedures such as Nissen Fundoplication which involves wrapping the fundus of the stomach around the lower esophagus and suturing it into place to augment the biomechanical function of the LES. A quantitative measurement of compliance can provide an indication of whether the wrap is too loose or too tight, the latter resulting in an increased LES stricture that could cause difficulty in swallowing. If LES compliance can be assessed intraoperatively, the wrap can be adjusted, preventing the need for a second procedure to correct the problem. What is needed is a device that can be easily and reliably positioned for measuring compliance of the natural or reconstructed LES or gastroesophageal junction and to provide reliable data that can be readily interpreted to produce a quick assessment.
SUMMARY OF THE INVENTION
The inventor of the present invention has determined that, rather than the pressure exerted by the LES, the compliance (or distensibility) of the LES is determinative in diagnosing the LES dysfunction in certain medical and surgical cases. Simply measuring the pressure exerted by the LES is insufficient because it is possible for a dysfunctional LES to have proper pressure values due to the tone of the LES muscle, despite having abnormal compliance. Thus, to perform a useful diagnosis, it is necessary to isolate compliance from muscle tone, which can only be done by relaxing the LES and changing its diameter in a controlled manner to detect the change in pressure that is needed to change the LES diameter. However, as mentioned above, the LES is ordinarily constricted, relaxing only briefly to allow passage between the esophagus and stomach.
The foregoing problems are solved and a technical advance is achieved in a method and apparatus for maintaining the LES in a relaxed state and measuring the compliance of the LES in vivo. According to the invention, the LES is relaxed by distending the esophagus at a suitable position above the LES with a first extendable member, such as a balloon. The balloon is inflated to relax and trigger motility of the esophagus, thereby simulating a natural swallowing response that permits measurement the amount of resistance provided by the LES without the underlying tonic interference. As a result, a pressure reading can be obtained which is a more clinically relevant measurement of the compliance of the LES.
To measure compliance of the LES, a second extendable member, such as a non-elastic or non-distensible balloon (or bag), is inserted within the LES and filled at prescribed air volume increments via a catheter. A non-elastic balloon is infinitely compliant in that the pressure inside will not change until the volume of air being introduced into the balloon is at least equal to the volume of the balloon upon fabrication. The pressure within the bag is measured by a suitable gauge at each change in volume. A volume/pressure curve and/or data table is generated. These data can then be compared to established compliance norms for making a diagnosis. The pressure is measured by a measurement device, such as a gauge or pressure meter, reading the inflation lumen communicating with the non-elastic (intrasphincteric) balloon. By repeated inflations of the esophageal balloon using increasing volumes of air to obtain an increased physiologic response, a volume vs. pressure curve can be esta
Agnew Charles W.
Odland Kathryn
Wilson-Cook Medical Incorporated
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