Catheter Guiding System

Cross Reference to Related Application

[0001] This application claims benefit of provisional application 60/955,145, filed August 10, 2007, the entire contents of which are hereby incorporated by reference. This filing is intended to be through the PCT, with specific activation of US patent review and option to extend to partner countries over the subsequent 30 months.

Field of the Invention

[0002] The invention described here relates to apparatus and methods to assist in the placement of a object such as a catheter into a patient, to reduce the incidence of complications associated with placing such objects.

Background

[0003] Medical practice often entails insertion of objects, such as catheters, into patients, often in locations with little tolerance for error. For example, physicians treat elevated intracerebral pressure associated with traumatic brain injury, stroke, intracerebral hemorrhage, and brain tumors by inserting catheters into the cerebral ventricles. Such ventriculostomy catheters drain the cerebrospinal fluid (CSF) and thus decrease the pressure within the brain.

[0004] The standard method of placing a ventriculostomy catheter uses anatomic landmarks to select an initial site of entry and course for the catheter. A coaxial stylet-catheter combination is pushed through a burr hole in the skull and into the brain parenchyma towards the anterior horn of the lateral ventricle. Correct placement is assumed if CSF is observed coming from the catheter.

[0005] Placement in the desired location may require several attempts, with each attempt increasing the risk of injury to critical structures in the brain. Even after multiple attempts, the tip of the catheter may end up outside the ventricular system entirely. In fact, studies quote misplacement rates as high as 11%. Multiple passes and misplacement may also cause catheter blockage, which itself requires yet another

attempt to replace the blocked catheter. Other complications of catheter placement include infection and bleeding, so minimizing the number of times a catheter must be placed is highly desirable.

[0006] Previous solutions to this problem have involved, for example, including an ultrasound probe inside the catheter to help the physician visualize the catheter's location, as described in US 5,690,117. In practice, however, current ultrasound probes cannot be threaded through the lumen of a standard ventriculostomy catheter to protrude from it, as required for a clear image, and merely placing the probe within the lumen (but not protruding from it) does not afford medically useful visualization of the surrounding tissue.

[0007] Therefore a need exists for a way to provide physicians with imaging information that will assist them in placing objects such as catheters in desired locations in the body.

Summary of the Invention

[0008] The present invention provides a method and apparatus to use imaging guidance to assist in placing a object such as a catheter into the body, thereby reducing the incidence of complications associated with blind placement.

[0009] The inventive device overcomes these difficulties by providing a peel-away guide from which an imaging probe, such as an ultrasound probe, protrudes, affording imaging of surrounding tissue. The peel- away guide is left in place while the imaging probe is removed and replaced with the object to be inserted, such as a catheter, which the peel-away guide directs into the desired location. After insertion of the object, the physician can remove the peel-away guide.

Brief description of the drawings (at end of document)

[0010] Figure 1 (a) shows one embodiment of a coaxial apparatus including a peel-away guide, a sterile probe-encasing stylus, and an ultrasound probe. Figure 1 (b) depicts one embodiment of a coaxial apparatus including a peel-away guide and a ventriculostomy catheter within the guide.

[0011] Figure 2 illustrates (a) one embodiment of an assembled ultrasound probe-peel-away guide apparatus outside the brain parenchyma, and (b) within the brain parenchyma (iii).

[0012] Figure 3 illustrates (a) one embodiment of a peel-away guide (i) within the brain parenchyma after the removal of the ultrasound-probe and sterile stylus; (b) the coaxial placement of a ventriculostomy catheter (ii) into the ventricle; (c) the ventriculostomy catheter (ii) in its final placement after removal of the peel-away guide.

[0013] Figure 4 shows an embodiment of the inventive apparatus in which a string is attached to the distal end of the ultrasound probe, with the proximal end accessible to the operator outside of the brain.

Detailed description of the Invention

[0014] For the sake of concreteness the invention is discussed in terms of inserting a ventriculostomy catheter into a cerebral ventricle under ultrasound guidance, but it will be apparent that the inventive apparatus and method also finds ready application for inserting a variety of objects into various locations in the body through use of various imaging modalities.

[0015] "Coaxial apparatus" refers to the combination of the inventive peel-away guide in conjunction with an imaging probe, stylus, and catheter or other object as a system for introducing the object into a desired location in the body.

[0016] Figure 1 (a) shows one embodiment of a coaxial apparatus 10 including a peel-away guide 20, a probe-encasing stylus 30, and an ultrasound probe 40. As depicted, stylus 30, containing ultrasound probe 40 within, is inserted through peel-away guide 20. Coaxial apparatus 10 is then advanced through the brain parenchyma (not shown) towards the ventricle (not shown). Figure 1 (b) depicts peel-away guide 20 and a catheter 50 within peel-away guide 20 . After ultrasound probe 40 and stylus 30 are removed from the brain parenchyma (not shown), catheter 50 is advanced coaxially via peel-away guide 20 into the ventricle (not shown).

[0017] Figure 2 (a) shows one embodiment of a coaxial apparatus 10 outside the brain parenchyma (not shown). Ultrasound probe 40 and surrounding stylus 30 are contained within peel-away guide 20. Probe 40 is connected to display 60, which depicts images from the tip of ultrasound probe 40. Figure 2 (b) shows coaxial apparatus 10 introduced into brain parenchyma 70. The tip of ultrasound probe 40 is just outside ventricle 80, and conveys images to display 60.

[0018] Figure 3 (a) illustrates peel-away guide 20 within brain parenchyma 70 after removal of ultrasound probe 40 and stylus 30. Figure 3 (b) shows the coaxial placement of catheter 50 into ventricle 80. Figure 3(c) depicts catheter 50 in place after removal of peel-away guide 20.

[0019] Figure 4 (a) shows an embodiment of apparatus 10 in which stylus 30 is disposed within peel- away guide 20 and surrounds ultrasound probe 40. In this embodiment string 90 (not shown) is attached to ultrasound probe 40, with the proximal end of string 90 is accessible to the operator outside of the brain. As shown in Figure 4 (b), tension on string 90 creates a bend in ultrasound probe 40, thereby providing greater imaging coverage from a probe that only sends and receives acoustic waves in a radial fashion. In another embodiment, string 90 is attached to stylus 30 instead of ultrasound probe 40.

[0020] In use, the surgeon first gains entry to the body in the standard fashion. For cranial surgery, for example, the surgeon commonly drills a burr hole in the skull. He then introduces an ultrasound probe 40 and surrounding stylus 30 within a peel-away guide 20 into the burr hole. Using the same anatomic landmarks as the standard blind procedure, the surgeon advances ultrasound probe 40 through brain parenchyma 70 to lateral ventricle 80, guided by ultrasound images. The surgeon then removes ultrasound probe 40 and stylus 30, leaving peel-away guide 20 in place. Then, using peel-away guide 20, the surgeon inserts catheter 50 coaxially through the peel-away guide 20 into lateral ventricle 80. Finally, the surgeon removes peel-away guide 20, leaving catheter 50 within ventricle 80.

[0021] In one embodiment, the peel-away guide is composed of a sterilizable polymer, such as a plastic, such as is well-known in the art. Similarly, the stylus can be composed of plastic or any other material

suitable for medical use (through being, e.g., sterilizable) of desired rigidity to facilitate navigation of the imaging probe within the patient's body.

[0022] The present invention is intended to be used with an imaging probe, which here refers to a probe inserted into the body that allows surgeon to visualize the location of the probe. Examples include probes bearing members visualizable by magnetic resonance imaging, including proton longitudinal and transverse spin relaxation times or Larmor frequencies {e.g., ¹⁹ F) that distinguish them from surrounding tissue. In a preferred embodiment, the imaging probe is an ultrasonic transducer/receiver.

[0023] In one embodiment the ultrasound probe includes a transducer that directs sound waves longitudinally along the axis of the probe or alternatively transversely to that axis. In the latter circumstance, to direct the ultrasound waves in a forward direction, a string may be attached to the distal end of the ultrasound probe. When pulled by the surgeon at the proximal end {i.e., the end further from the patient), the string orients the transducer transversely to the axis of the probe, thereby providing a forward view.

[0024] While the inventive apparatus and method can be used in many parts of the body, they find particular application in neurosurgery, especially intracranial neurosurgery.

Claims

1 . A surgical apparatus comprising: a peel-away guide having a proximal end, a distal end, and a longitudinal bore throughout, and a stylus having a longitudinal bore throughout, the stylus fitting within the peel-away guide, and being removable from it.

2. The apparatus of claim 1, further comprising an imaging probe adapted to fit within the stylus.

3. The apparatus of claim 2, wherein the imaging probe is selected from the group consisting of a magnetic resonance imaging probe and an ultrasonic probe.

4. The apparatus of claim 3, wherein the imaging probe is an ultrasonic probe.