Atlas of Pain Medicine Procedures 1st Edition

SECTION I

BASIC APPLICATIONS

CHAPTER 5

Equipment Used in Pain Management

Vikram B. Patel

INTRODUCTION

Interventional pain management involves the use of image-guided procedures as well as targeted delivery of medications to modulate pain, symptoms, and disease. To facilitate these procedures, an interventionalist has to utilize a variety of equipment, ranging from simple needles for a trigger point injections to the use of an MRI or a CT scanner for more complex procedures.

Without proper equipment, the procedures cannot be done in a reliable manner and are basically described as “blind” techniques. This chapter covers various types of needles and specialized catheters and syringes. Some major equipment such as a fluoroscopy machine is covered elsewhere in this atlas (see Chapters 1 and 4).

RELEVANCE OF ANATOMY

Although it is necessary to consider the anatomical variations in males, females, adults, and children, the basic need for most of the equipment remains the same. However, depending on the patient’s size and type of a procedure, one must consider the proper type and length of needles, anticipate difficulties, and be prepared for possible complications in case ideal equipment is not available. For example, a larger patient would need a longer needle (and choosing a shorter needle may lead to multiple or failed attempts as well as improper placement of the needle), a sharp needle instead of a pencil point needle may lead to nerve damage, a spinal needle used for epidural access would lead to higher rates of dural punctures. Without proper equipment for guidance of a needle (such as a fluoroscopy unit or an ultrasound unit), the needle may end up in an unintended location and even cause unintentional trauma to tissue.

BASIC CONCERNS AND CONTRAINDICATIONS

Based on the procedure to be performed, it is inappropriate to use certain equipment such as a long needle for a shallow procedure which can lead to higher rate of complications.

TYPES OF EQUIPMENT

Needles (Nonepidural Placements)

Quincke (Figure 5-1)

Figure 5-1. Quincke needle—note the sharp tip of the needle which has a cutting edge. (Used with permission from Aakash Patel.)

• Most common type of bevel seen in needles.
• It is a sharp bevel that facilitates penetration of the skin.
• Various needles that have such bevels are intended for intramuscular and intravenous access, biopsies, subcutaneous drug delivery, etc.
• Spinal needles are mainly available with this type of bevel and are commonly used for several interventional procedures.

Pencil point (Figure 5-2)

Figure 5-2. Pencil point needle. (Used with permission from Aakash Patel.)

• This needle has a tip that is conical in shape.
• The bevel is on the side of the needle shaft at the conical tip.
• Although considered a “blunt” type needle, it can easily penetrate delicate structures such as a vein or even an artery if the vessel is fixed and immovable.

Bullet tip (Figure 5-3)

Figure 5-3. Bullet tip needle. (Used with permission from Aakash Patel.)

• Similar to the pencil point, but is completely blunt at the tip.
• Safer for certain procedures that are in the close proximity of nerves and blood vessels.
• Bevel is at the side of the tip.
• A sharp-tipped introducer is a must as this tip cannot penetrate the skin.

“B” bevel

• Commonly used for nerve blocks. The relatively short and noncutting tip makes it a safer choice for a peripheral nerve block.

Chiba needle (Figure 5-4)

Figure 5-4. Chiba needle—note the angled bevel with a noncutting edge. (Used with permission from Aakash Patel.)

• It has a very short bevel with a noncutting tip.
• Suitable for deeper procedures when a needle has to traverse delicate issues on its way to the target such as a lumbar sympathetic block or celiac plexus block.

Day needle (Figure 5-5)

Figure 5-5. Day needle. (Used with permission from Epimed International, Inc.)

• Bullet tip Coudé needle (see below) used for various interventional procedures in the vicinity of delicate tissues.
• The bullet tip minimizes the damage to such tissues as it has a noncutting tip.

Huber needle (Figure 5-6)

Figure 5-6. Huber needle—the tip has a noncoring edge, which is safer for the silastic injection port. (Used with permission from Aakash Patel.)

• Used for accessing a sub-cutaneous reservoir or a port during a continuous infusion such as used in a long term epidural infusion.
• Angled shaft helps keep the needle flat against the skin while it is placed within the port.
• The tip (similar to a Touhy needle) is also specially designed to be “noncoring” so that it does not damage the silastic material over the entry port.

Needles (Epidural Placements)

Touhy needle (Figure 5-7)

Figure 5-7. Touhy needle—the slight curve helps guide a catheter at an angle and provides a slightly blunter edge to prevent a dural puncture. (Used with permission from Aakash Patel.)

• A blunter tip as the opening is slightly on the side and the tip is curved.
• Helps facilitate passage of a catheter and guides it at an angle hence letting the catheter slide out of the needle at a shallower angle and thus minimizing the risk of dural punctures.

Crawford needle—another type of an epidural needle with a short bevel that is relatively atraumatic

Hustead needle

• Epidural needle with a short bevel—slightly shorter than a Touhy needle.
• A rounded “heel”—the proximal aspect of the bevel was designed to reduce damage to the catheter if it is withdrawn through the needle.

RX Coudé needle (Figure 5-8)

Figure 5-8. RX Coudé needle.

• Epidural access needle specially designed for placement of catheters.
• The bevel (along with the stylus) makes a flat surface that can be placed parallel to the ligamentum flavum/dura and hence minimizes accidental dural puncture.
• Once in the epidural space, the needle is rotated towards the direction of a catheter placement.

Touhy needle with flexible introducer cannula (FIC) (Figure 5-9)

Figure 5-9. Touhy needle with flexible introducer cannula (FIC). The Racz catheter is seen within the FIC.

• This set is used for epidural adhesiolysis using a Racz catheter.
• The soft plastic FIC minimizes damage to the Racz, or spring tip catheter while it is manipulated during the adhesiolysis procedure.
• The FIC may have a bend at the distal end to facilitate guidance of the catheter in either direction once inside the caudal canal.
• A regular Touhy needle may cause damage (shearing) of the outer covering of the catheter which may then break and stay within the epidural space.
• Once the Touhy with FIC is introduced inside the caudal canal, the Touhy needle is removed leaving the FIC in place within the caudal epidural space. The Racz catheter is then introduced through this FIC.

Fluoroscopy Equipment

• Usually a mobile setup—also called a C-arm due to the design.
• Certain fixed fluoroscopic setups such as the ones used for interventional cardiology may also be used for a dual exposure in procedures such as a vertebroplasty.
• Most modern machines have the capability to enhance the images using digital technology and thus minimizing radiation exposure.
• They also have several other modes which additionally reduce the radiation (low dose, pulsed mode).
• Pulsed mode delivers the X-rays as pulses rather than a continuous radiation delivery.
• Number of pulses per second may be selectable in certain machines.
• Usual pulsed mode parameters are 3 pulses/min, 10 pulses/min, etc.
• A “low dose” setting can further reduce the radiation exposure while maintaining a good image quality through digital enhancement.
• Newer monitors have flat panel LCD screens. Some also have touch screens to facilitate fast interaction with the machine. Usual setup includes 2 monitors out of which 1 can be used to display a previous image for comparison.
• Storage of images in a C-arm is important for documentation and record keeping.
• Older machines are able to store the images on a hard drive, the hard copies need to be printed on a thermal paper.
• The newer machines have various options for image storage and transport ranging from a CD to a USB drive using digitized images.
• Images can also be directly transmitted from the machine to an archive, using DICOM (digital imaging and communications) technology, which can then be interfaced with electronic medical records software.

Radiofrequency Generators

• Radiofrequency energy has been used to create tissue lesions for several decades.
• The first commercial RF generator was built in 1952.
• The RF generators are now more advanced and reliable and are manufactured by several companies.

The latest technology includes a touch screen interface and automated lesioning with predefined parameters.

Radiofrequency parameters:

• Conventional radiofrequency—uses higher temperature parameters to create the lesion, typically a small nerve such as the medial branches supplying a facet joint
• Pulsed radiofrequency

   Application of short bursts of radio-frequency energy.

   2 bursts/s, 20 ms each at 500,000 Hz.

   Output at 45 V, temperature reaches ˜42°C.

   Applied directly to the nervous tissue.

   As the tip has the most dense electric field, it can be applied perpendicular to the nerve.

   There is no nerve damage (neurolysis) at 42°C temperature and the myelinated as well as unmyelinated nerve fibers remain normal in morphology.

   Safer for use over superficial nerves (no risk of skin ulceration), cervical region (with several sensitive structures).

• Single lesion—traditionally used for thermal neurolysis of the medial branches
• Multiple lesions—used mainly for the sacroiliac joint denervation due to its expansive nerve supply
• Bipolar lesions

   Also used for the sacroiliac joint with two radiofrequency needles placed in close proximity (˜5 mm) of each other.

   Multiple lesions are created along the joint border for the sacroiliac joint.

• Cooled radiofrequency

   Newer technology using a water cooled cannula during the lesioning.

   Rational is that the charred tissue created during a conventional radiofrequency lesioning limits the spread of the lesion and cooling the tip of the RF cannula can help create a larger lesion.

   Helpful in thoracic spine where the medial branches supplying the facet joints are not “plastered” to the bone but rather floating more dorsally. A larger spherical lesion created by the cooled RF generator can satisfactorily capture these medial branches.

   Also effective in denervating the sacroiliac joint which similarly has “floating” nerve branches supplying the joint.

   Caution is necessary while using this technique for other areas as the lesion (which can be quite large) may extend beyond the intended target and potentially damage an unintended nerve or other vital structure.

Cryoablation Equipment

• The use of cryoablation has decreased in pain management during the past decade.
• The technology was used to ablate the nerves at various locations for the treatment of pain using a freezing technique called cryoablation.
• Also used to ablate other tissues such as a tumor.
• Peripheral nerve ablations were frequently performed using this technique including lumbar medial branches and intercostal nerves.
• As the nerve sheath remains intact after cryoablation, a neuroma formation is less likely when the nerve regenerates.
• The equipment delivers compressed gas to the tip of the probe thus creating a freeze which ablates the tissue due to ice crystal formation and apoptosis (with up to –75°C).
• The probes are larger, bulkier, cannot be bent and require extreme care in handling.
• Addition of a gas source also adds to the bulk of the equipment and reduces portability.

Other Specialized Equipment

Specialized Syringes

This is pressure monitoring manometric syringe with controlled rate of injection (Figure 5-10A, B).

Figure 5-10. (A) Controlled injection syringe with an external cable for manometric measurements. (B) Controlled injection syringe with a built-in digital manometer and infrared transmitting capability for printing the data.

Used for manometric provocation discography

• These syringes have a controlled injection rate.
• The plunger of the syringe is threaded and a very small amount of injectate (usually 0.2 mL) can be injected with each turn of the plunger.
• Some newer syringes have a built-in manometer, which is digital and can transmit the data to a printer.
• Older syringes had an external connection cable which is then connected to an external manometric measurement device along with a printer.

Dual needle sets for discography (Figure 5-11A, B).

Figure 5-11. (A) Discography needle set. (B) Discography needle set with a curved inner needle to facilitate proper placement within the nucleus by helping steer the needle.

These needles are prepackaged by some companies to include a larger bore needle, which acts as an introducer through which a thinner needle can be introduced into the nucleus of the disc.

• Advantages to these needle sets include lower risk of infection and smaller puncture into the annulus.
• A curved inner needle can help steer it for proper central placement within the nucleus with a single pass and without multiple insertions.

Specialized Catheters

Racz catheter—used for epidural adhesiolysis (Figure 5-12)

• This is a spring-tipped steerable catheter.
• It is used for epidural adhesiolysis as well as site-specific placement of drugs.
• Various lengths are available along with varying stiffness of the catheter.
• It has a stylet that can be used to steer the catheter once slightly bent at the tip.

Figure 5-12. Racz Brevi-XL catheter with the injection port attachment. Note the slightly withdrawn stylet that normally extends up to the tip of the catheter. The area slightly proximal to the tip is where the injectate exits the catheter. (Used with permission from Epimed International, Inc.)

Stimulating catheter—used for continuous plexus blocks, identifying needle placement

• This type of a catheter provides a visual guidance to the catheter placement with continuing muscle twitches while advancing the catheter along the plexus.
• The catheter is placed through a Touhy type needle which has a stimulating attachment.
• Once the needle is in place, the catheter is advanced through the needle and the stimulating connection is shifted to the catheter from the needle.
• As the catheter advances, the resulting stimulation is visualized and a loss of stimulation provides a visual clue as to the catheter diverting away from the nerve bundle.

DuPen^® catheter— used for long-term epidural or spinal infusions either externalized or connected to a subcutaneous injection port. This injection port can then be accessed with a Huber needle.

Although there are several other types of injection devices such as the ones used in vertebroplasty or kyphoplasty, etc, they are usually included in the kit and hence not mentioned in this chapter.