Rectal probe with disposable balloon assembly

A reusable temperature sensing probe assembly comprises a temperature sensor strip extending from one end of a handle. The temperature sensor strip carries at least one temperature sensor for measuring temperature within a body cavity of a person, such as the rectum. The handle/temperature sensor strip is reversibly positionable within a unitary balloon/sleeve assembly comprised of a balloon portion and a sleeve portion. The balloon portion is comprised of a first interior space configured to hold the temperature sensor stip and a second interior space separate from the first interior space that is configured for inflation. An inflation tube has one portion sealed within the second interior space of the balloon portion and a second portion which extends through the sleeve portion for connection to a fluid source.

BACKGROUND OF THE INVENTION

The present invention relates to a temperature sensing probe for sensing rectal temperature of a patient. In particular, the present invention relates to a temperature sensing probe comprising a reusable handle and sensor array with a disposable balloon/sleeve assembly.

The prostate gland is a complex, chestnut-shaped organ which encircles the urethra immediately below the bladder and lies immediately adjacent the rectum. This relatively small organ, which is the most frequently diseased of all internal organs, is the site of a common affliction among older men, benign prostatic hyperplasia (BPH), as well as a more serious affliction, cancer. BPH is a non-malignant, bilateral nodular tumorous expansion of prostate tissue occurring mainly in the transition zone of the prostate. Left untreated, BPH causes obstruction of the urethra which usually results in increased urinary frequency, urgency, incontinence, nocturia and slow or interrupted urinary stream. BPH may also result in more severe complications, such as urinary tract infection, acute urinary retention, hydronephrosis and uraemia.

A fairly recent treatment method for BPH involves microwave thermal therapy, in which microwave energy is employed to elevate the temperature of tissue surrounding the prostatic urethra above about 45° C., thereby thermally damaging the tumorous BPH tissue. Delivery of microwave energy to tumorous prostatic tissue is generally accomplished by a microwave antenna-containing applicator, which is positioned within a body cavity adjacent the prostate gland. The microwave antenna, when energized, heats adjacent tissue due to molecular excitation and generates a radiation pattern which encompasses and necroses the tumorous prostatic tissue. The necrosed intraprostatic tissue is subsequently reabsorbed by the body, thereby relieving an individual from the symptoms of BPH.

One type of thermal therapy treatment of BPH is transurethral microwave thermotherapy. This method of treatment positions a Foley-type catheter containing a microwave antenna within the urethra adjacent to the prostate gland. The microwave antenna is energized to heat a selected volume of tumorous prostatic tissue surrounding the urethra to about 45° C. for a time sufficient to necrose the selected volume of tissue.

Due to the relatively close proximity of the rectum to the urethra, it is critically important in the course of transurethral microwave thermotherapy that the temperature of the rectum is maintained below a threshold temperature. Rectal temperatures greater than the threshold may cause damage to the rectum.

Typically, the temperature of rectal tissue adjacent the prostate is measured and monitored with a rectal temperature sensing probe. The probe supports one or more temperature sensing elements against a wall of the rectum adjacent to the prostate to provide the physician with essential information for controlling the location and degree of heat induced in the prostate. In providing a rectal probe to measure the temperature of rectal tissue adjacent the prostate, it is desirable to maintain the position of a temperature sensing device supported by the probe directly adjacent to the rectal wall to provide optimally accurate temperature readings. There is a continuing need for an improved rectal temperature sensing probe.

BRIEF SUMMARY OF THE INVENTION

The present invention is a temperature sensing probe assembly comprising a reusable temperature sensor/handle assembly and a balloon/sleeve assembly. The temperature sensor/handle assembly is comprised of a handle having a length, a width, a first end and a second end, and a temperature sensor strip carried by the handle and extending from the first end of the handle. The temperature sensor strip comprises a temperature sensor spaced from the first end. The temperature sensor is configured for connection to a thermometry device. The balloon/sleeve assembly comprises opposing first and second polymeric layers configured to define a balloon portion and a sleeve portion. The balloon portion further comprising a first interior space in communication with an interior space of the sleeve portion, and a second interior space isolated from the first interior space and the interior space of the sleeve portion. A first tube portion of an inflation tube is sealingly connected within the second interior space of the balloon portion and is configured with an inflation port. A second tube portion of the inflation tube extends through the sleeve portion and is configured for connection to a fluid source. The handle is reversibly positionable within the sleeve portion and the temperature sensor strip is reversibly positionable within the first interior space of the balloon portion.

While the above-identified drawing figures set forth preferred embodiments of the invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the present invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. It should be specifically noted that the figures have not been drawn to scale, as it has been necessary to enlarge certain portions for clarity.

DETAILED DESCRIPTION

FIG. 1is a top view of the rectal temperature sensing probe10of the present invention. As shown inFIG. 1, probe10is generally comprised of a probe handle12and a balloon/sleeve assembly14. The probe handle12includes a handle body16and a temperature sensor array18which carries a plurality of longitudinally spaced temperature sensors20. In one embodiment, handle16is preferably formed of silicone in a molding process that captures a sensor cable22, which is electrically connected to sensor array18. Handle body16has a length of about 6.0 inches to about 6.5 inches and a nominal diameter of about 0.5 inches.

Temperature sensor array18is comprised of the plurality of temperature sensors20bonded to a flexible circuit which is housed within a protective strip. A suitable temperature sensor array is fully described in U.S. Pat. No. 5,792,070, which is incorporated herein by reference. In one embodiment, temperature sensor array18extends from a proximal end24of handle body16, with temperature sensor20A positioned approximately 1.75 inches to about 2.15 inches from proximal end24. Temperature sensor array18has a length extending from proximal end24of handle body16of about 4.4 inches to about 4.6 inches. Temperature sensors20are oriented and spaced to sense a temperature of a wall of the rectum facing the prostate when probe10is properly positioned within the rectum of a patient undergoing a heat treatment of the prostate. Sensor cable22is configured for connection to a rectal thermometry unit to transmit a signal representative of the sensed wall temperature, as is fully described in the aforementioned U.S. Pat. No. 5,792,070.

The balloon/sleeve assembly14includes a balloon portion26, which holds and carries temperature sensor array18, and a sleeve portion28, which enshrouds a portion of the handle body16. The balloon/sleeve assembly14is designed to be a disposable unit that can be separated from the probe handle12after use of probe10. The balloon portion26and sleeve portion28are formed from layers of a flexible, biocompatible polymer, such as polyurethane, in a manner to be more fully described. As shown inFIG. 1, the balloon portion26and sleeve portion28may be transparent to enable verification of a proper positioning of the temperature sensor array18within the balloon portion26. The balloon portion26is formed with a central channel30, which positions temperature sensor array18in a proper orientation relative to an outer surface32of the balloon portion26. With temperature sensor array18properly positioned within channel30, proximal end24of the probe handle12lies generally adjacent to a waist34of the balloon portion26, which is a point of transition from the balloon portion26to the sleeve portion28. Balloon portion26is dimensioned to fit within the rectum of a patient and engage the rectal wall when the balloon portion26is inflated, with the proximal end24of the probe handle12remaining external to the rectum. An inflation tube36, which is in communication with a fluid source, extends along the probe handle12and into the balloon portion26to inflate the balloon portion26. The sleeve portion28is sized to permit easy assembly and disassembly of the probe handle12from the balloon/sleeve assembly14and to cover the handle body16when probe10is in use.

FIG. 2is a bottom view of the probe10ofFIG. 1. As shown inFIG. 2, inflation tube36extends along the probe handle body16within a channel38formed relative to a bottom surface40of handle body16. Inflation tube36extends to a tip42of balloon portion26and is configured with a bulbous end44in contact with the tip42. The bulbous end44is fixed relative to the inflation tube36to provide a blunt surface in contact with an inner surface of balloon portion26for the safety of the patient in the event tip42contacts patient tissues. In one embodiment, inflation tube36is provided with a plurality of openings46within balloon portion26for the introduction of an inflation medium. The plurality of openings46are oriented on opposite sides of inflation tube36to provide flexibility in a preferred plane to allow for anterior rectal wall contact of temperature sensors20while maintaining column strength/flexural rigidity of inflation tube36sufficient for insertion of balloon portion26into the rectum. For increased flexibility at waist34, the size of openings46at or near to waist34may increased or elongated.

Channel38of handle body16is dimensioned to secure inflation tube36relative to handle body16when inflation tube36is positioned therein. Accordingly, the elongated opening48of channel38has a width that is less than an outer diameter of inflation tube36when handle body16is unstressed. Owing to the flexible characteristics of the silicone material forming handle body16, the opening48, however, can yield sufficiently to permit the inflation tube36to be press fit into and removed from channel38with an application of sufficient force. In the absence of such force, the edges of opening48slightly overlap opposite sides of inflation tube36to retain inflation tube36within channel38.

A longitudinal movement of inflation tube36relative to handle body16is prevented by means of a lock assembly formed between a key50secured to inflation tube36and a corresponding key slot formed in handle body16transverse to channel38. The key slot in handle body16is positioned to align with the key50when temperature sensing array18is fully inserted into central channel30. The lock assembly further ensures that a precise location of the temperature sensor array18within channel30(shown inFIG. 1) is maintained when probe10is in use.

FIG. 3is an exploded bottom view of probe10with the probe handle12separated from the balloon/sleeve assembly14. As shown inFIG. 3, probe handle12is removable and separable from the balloon/sleeve assembly14to permit probe handle12, i.e., and the temperature sensing array18, to be reused with a new sterile balloon/sleeve assembly. The balloon/sleeve assembly14includes the inflation tube36, which is connected between layers of the polymer material forming a balloon at the waist34of the balloon portion26, as will be described in greater detail. As shown inFIG. 3A, the key50consists of a polymeric member having a flat edge portion52, a curved edge portion54and a hole56passing through the member to permit key50to be slid into a position on inflation tube36corresponding to key slot58in handle body16. Once key50is properly positioned, it is secured to inflation tube36by a suitable adhesive.

FIG. 4is an enlarged perspective view of the probe handle12, which shows that the handle body16is configured with a curved upper surface60and a flat lower surface62. This configuration of handle body16facilitates a proper orientation of the probe10relative to a patient and monitoring of the proper orientation during use. In a proper orientation, the flat lower surface62of handle body16contacts a treatment surface occupied by a patient in the supine position and is maintained in contact with the treatment surface by the weight of the patient on the handle body16. The configuration of handle body16thus inhibits any twisting of probe10by minor changes of position of the patient on the treatment surface.

As shown inFIG. 4, temperature sensor array18extends from the proximal end24of handle body16at an upper extent of handle body16, and sensor cable22extends rearward of handle body16at a comparable upper extent. Temperature sensor array18is oriented in a plane that is generally parallel with the flat lower surface62of handle body16, with sensors20oriented on the upper surface of the flexible circuit.

Channel38is generally centrally located relative to the flat lower surface62. Channel38is defined by a curved inner wall64which has an inner diameter that approximates the outer diameter of the inflation tube36for retaining the inflation tube36in channel38. The width of opening48of channel38is smaller than the inner diameter of inner wall64, which aids in the retention of inflation tube36within channel38. As shown in phantom, the key slot54is dimensioned and configured complimentary to key50to form a friction fit with key50when it is position within key slot54.

FIG. 5is an exploded view of the balloon/sleeve assembly14. As shown inFIG. 5, in one embodiment, the balloon/sleeve assembly14is comprised of a plurality of overlying and interconnected layers70,72,74and76which are connected together along a common peripheral edge such as by heat welding. Layers70and76are each a unitary layer of polymer that defines the top and bottom layers, respectively, of balloon portion26and the sleeve portion28of the balloon/sleeve assembly14. Edge portion77of layers70and76remain unconnected for inserting and removing probe handle12from the balloon/sleeve assembly14. Layers72and74are also each a unitary layer of polymer that is a postage stamp of balloon portion26, extending from a first end42A to an opposite end78corresponding to waist34of balloon/sleeve assembly14.

Positioned between layers70and72adjacent to end78of layer72is a guide tube80, which facilitates insertion of the temperature sensor array18into the balloon portion26. Guide tube80is formed of a flexible polymer, such a Fluorinated Ethylene Plastic or Fluorinated Ethylene Propylene and is skived along a portion of the tube wall facing layer70to minimize the amount of material of balloon portion26that gets positioned within a patient, i.e., for patient comfort. Opposing edge portions82of guide tube80are secured to the peripheral edge regions of layers70and72to hold guide tube80in place. End78of layer72is left unconnected relative to layer70, such that guide tube80separates layers70and72slightly for easy insertion of the temperature sensor array18. Layers70and72are further interconnected by heat welding along seal lines84which define channel30for the temperature sensor array18.

Positioned between layers74and76is the inflation tube36. Inflation tube36is oriented with the flat edge portion52of key50facing layer76and the axis of openings46perpendicular to the flat edge portion52of key50. Inflation tube36is sealingly connected between layers74and76at the waist34and along end78. Layers74and76thereby define an inflatable balloon, which when inflated results in layer74bearing directly against layer72and indirectly against layer70to urge the temperature sensor array18in close proximity to the wall of the rectum to be monitored. Layer76in turn bears against an opposite rectal wall portion to secure the balloon portion26in place in the rectum. In a preferred embodiment layers70,72,74and76have a wall thickness of about 0.2 mil (i.e., about 0.002 inches), which provides for good heat transfer across layer70to sensors20of the temperature sensor array18.

In an alternate embodiment, balloon/sleeve assembly14may comprise only three layers consisting of layers70,72and76that are connected in the manner described above. In such an embodiment, layers70and72are secured together about the perimeter and guide tube80is secured therebetween as previously described. Layers70and72are then heat sealed along seal lines84to form channel30. Thereafter, inflation tube is positioned between layers76and72and secured by sealing layer76to layer72about the perimeter and by sealing the side of layer72facing layer76to layer76along end78.

In yet another alternate embodiment, layer72may be sized and shaped to define channel30and sealed about its perimeter to layer70, with guide tube80positioned as previously described between layers70and72. Inflation tube is positioned between layers70and76and secured by sealing layer70to layer76about the perimeter and by sealing the side of layer70facing layer76to layer76along end78.

FIG. 6is a cross-sectional view of the waist34of balloon portion26, which shows the peripheral heat welds90that interconnect peripheral edge portions of layers70,72,74and76.FIG. 6also shows adhesive layers92, which secure the opposing edge portions82of guide tube80to layers70and72. Finally, adhesive layer94is shown interconnecting end78of layer74to layer76and inflation tube36to create a fluid-tight seal at end78and thereby form a balloon between layers74and76that is inflatable and deflatable via the inflation tube36.

FIG. 7is a top view of probe handle12being introduced into balloon/sleeve assembly14for assembly of rectal temperature sensing probe10. As shown inFIG. 7, probe handle12is inserted through sleeve portion28and temperature sensor array18is positioned within guide tube80. Sleeve portion28may be folded back over balloon portion26to facilitate locating guide tube80. In one embodiment, guide tube80is formed from a distinct color that is readily detectable through the transparent material forming balloon/sleeve assembly14, which makes the opening for temperature sensor array18into channel30easy to identify. Probe handle12is advanced until temperature sensor array18is completely within channel30, which occurs when key50on inflation tube36is aligned with the key slot54in the handle body16. Inflation tube36is then press fit through opening48and into channel38along the length of handle body16and key50is press fit into key slot54. With sleeve28covering handle body16, temperature sensing probe10is then ready for insertion and use in a patient.

Inflation tube36is flexible but with sufficient longitudinal stiffness to enable advancement of tip42of balloon portion26into the desired position within the rectum of a patient. Balloon portion26is sized to engage the rectal wall when an inflation medium is introduced via the inflation tube36between layers74and76of the balloon portion26. With the inflation medium evacuated from the balloon formed by layers74and76, balloon portion26reduces to a more compact dimension for easy removal of the balloon portion26from the patient. To remove the balloon/sleeve assembly14from the probe handle12, the sleeve portion28is everted over balloon portion26to isolate the contaminated surface of balloon portion26. Inflation tube36and key50are then easily withdrawn from the channel38and key slot58in the handle body16. With the inflation tube36separated from the handle body16, probe handle12easily slides out of the balloon/sleeve assembly for subsequent re-use with a new balloon/sleeve assembly.