System and method using the rectal mucosal membrane for inducing hypothermia and warming

Abstract

A system and method for cooling and warming the central nervous system of a patient comprises a delivery tube with one of the ends couplable to a supply of fluid. A head structure is coupled to the other end of the delivery tube and cooling or warming fluid is directed through the tube to the head structure. The head structure is configured to be placed within the rectal cavity of a patient such that either a contact surface on the head structure or the fluid itself directly contacts a portion of the rectal mucosal membrane. A means for reversing the vertebral venous flow of blood through Batson's plexus supplies cooled or warmed blood directly to the vertebral structures. Unique methods of utilizing the system to selectively cool and warm the central nervous system structures of a patient are set forth herein.

Description

RELATED APPLICATION [0001] This application is a Divisional of U. S. patent application Ser. No. 10 / 224,023, entitled “System and Method Using the Rectal Mucosal Membrane for Inducing Hypothermia and Warming,” and filed Aug. 20, 2002, the disclosure of which is hereby incorporated herein by reference in its entirety.FIELD THE INVENTION [0002] The present invention relates generally to a system and method for cooling and warming the body and specifically relates to a system and method for selectively inducing hypothermia or warming in the central nervous system. BACKGROUND OF THE INVENTION [0003] Hypothermia, which is the condition of lowered normal body temperature in a warm blooded animal, has been used therapeutically for the treatment of human brain injury, spinal cord injury, and spinal cord ischemia for many years. Therapeutic hypothermia is used as a neural protectant in situations where there is central nervous system ischemia, trauma, or hypoxia. Such situations can occur fr...

AI Technical Summary

Benefits of technology

[0010] Rectal mucosal membrane cooling / warming in conjunction with the reversal of blood flow through Batson's plexus provides direct cooling / warming of the spinal structures and other central nervous system areas. Reversal of flow in Batson's plexus refers to the physical phenomenon of reversing the flow of blood through the veins of the vertebral structures when intraabdominal pressure is applied. Normally, the vertebral venous plexus in the pelvis, sacrum and lumbar spine assist in carrying venous blood from the meningorachidian veins of the vertebral structures, including the spinal cord, to the sacrum, the sacral plexus, the iliac veins and ultimately to the inferior vena cava and to the heart. However, the vertebral venous plexus or Batson's plexus is valveless, so blood is free to flow in either direction. The Batson effect occurs upon increased intraabdominal pressure, which causes reversal of pelvic and lumbar venous flow. Venous blood then flows from the inferior vena cava and sacral venous plexus into the meningorachidian blood vessels. In short, normal blood flow occurs from the spinal column toward the heart, but under Batson's described effect, blood flow can occur in the opposite direction, providing blood flow back to the spinal structures.

[0011] By using Batson's plexus reverse blood flow by increased intraabdominal pressure in conjunction with cooling / warming of the blood draining the rectal mucosal membranes, internal cooling / warming is more efficiently and effectively accomplished at the spinal cord and brain, such as to induce hypothermia and recover from the hypothermia without the drawbacks of external or invasive techniques. In one embodiment of the invention, the head structure of the system is placed or positioned within the outermost two-thirds of the rectal cavity, commonly known as the ampulla. Caloric energy is transferred between the rectal mucosal membrane and the head structure and fluid, thereby cooling or warming, respectively, the blood draining the ampulla. While this is done, the direction of the vertebral venous blood flow is reversed so as to selectively direct the cooled or warmed blood retrograde through Batson's plexus and into the spinal structures, and with prolonged reversal to cranial structures.

[0017] The head structure can come in a variety of shapes and configurations. In one embodiment, the head structure is in a compressed form before insertion into the rectal cavity, and is thereafter able to expand once inside the rectal cavity. This allows for ease of insertion with minimal discomfort to the patient, while permitting maximal contact with the rectal mucosal membrane after insertion. In one embodiment, the head structure, now inside the rectal cavity, is able to further enlarge in size in direct relation to the delivery flow rate of the fluid from the delivery tube. In this embodiment, the head structure can be a flexible elongated bag that expands and enlarges in size as the fluid is delivered. In such an embodiment, the fluid is preferably delivered by a pump apparatus.

[0019] In yet another embodiment of the system, the cooling / warming head structure is configured having a proximal bulb and a distal bulb positioned in tandem to each other. The proximal end of rectal cavity is defined herein for illustrative purposes, as being the end proximal to the anal outlet. The distal end or area is then distal to the anal outlet. In one such tandem bulb configuration of the head structure, the proximal bulb (closest to the anal outlet) receives cooling fluid while the distal bulb (deeper into the rectum or colon; further away from the anal outlet) remains warm or non-cooled. The proximal bulb is positioned in the portion of the rectal cavity, which is drained by the inferior and middle rectal veins such that the outermost two-thirds of the rectum, or ampulla, will be selectively cooled or warmed. The inferior and middle rectal veins directly supply the spinal cord and the central nervous system structures when intraabdominal pressure is applied to reverse the blood flow through Batson's plexus. The warm (non-cooled), distal bulb can be positioned in the innermost one-third of the rectum to prevent cooling of that portion of the rectal mucosal membrane drained by the superior rectal vein. The superior rectal vein does not participate in Batson's plexus reversal of blood flow. Thus, the warm or non-cooled bulb is able to prevent portions of the body not related to the vertebral structures and / or the central nervous system from being actively cooled. In this manner, with the proximal bulb actively cooling or warming the spine and central nervous system structures and the distal bulb acting to keep other structures from being actively cooled or warmed, selective cooling or warming of the central nervous system can be accomplished. As discussed herein, the bulb which is generally not participating in the active cooling or warming may be maintained at a temperature that does not significantly affect the body or which prevents the cooling / warming of the other bulb from significantly affecting portions of the body.

Problems solved by technology

Surface techniques for achieving and maintaining central nervous system hypothermia are generally unsatisfactory for a number of reasons.

Further, the inertia produced by a steady drop in temperature can produce an “overshoot” condition in which organ damage from excessive hypothermia can occur.

Cooling by cold blankets and dressings is also often uncomfortable and induces shivering in the patient.

Furthermore, there is a risk of body surface injury, and the need to anesthetize for deep hypothermia is often required.

Similar drawbacks occur in warming or re-warming the body, such as re-warming a patient after hypothermia.

Internal cooling, on the other hand, is an invasive process which is associated with other problems, including infection, thrombosis, arrhythmia, and cardiac ischemia.

Another problem is that the entire body is necessarily cooled in situations where only the central nervous system should be cooled.

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