Endoscopic Sphincterotomy Periprocedural Care

Updated: Dec 03, 2015
  • Author: Priya A Jamidar, MD, FACG, FASGE; Chief Editor: Kurt E Roberts, MD  more...
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Periprocedural Care

Equipment

Papillotomes, guide wires, and electrosurgical generators are the equipment discussed in this topic.

Papillotomes

Papillotomes come in a number of different configurations, broadly grouped into the following three types:

  • Pull
  • Push
  • Needle-knife

The most commonly used papillotome is the pull-type version, also known as Erlangen. This consists of a wire-loop partially enclosed in a Teflon catheter. The wire exits the catheter roughly 3 cm before its distal end and reenters the catheter roughly 3 mm from its tip. The portion of catheter distal to the reentry point is referred to as the nose. The catheter becomes bowed when the wire is tightened, allowing the exposed wire to be brought away from the catheter. Several ways exist for distinguishing the various pull-type sphincterotomes, including nose length, length of the diathermy wire, and number of lumens.

The nose length can be further divided into short and long, though long-nose devices are rarely used today. The short-nose devices are more responsive to bowing, which translates into more control during sphincterotomy; however, they are more likely to become inadvertently dislodged from the bile duct.

The diathermy wire varies with regard to the length of wire exposed (range, 15-40 mm). Longer-wire devices are more likely to enter the papilla in the correct orientation by following the natural curve of the endoscope. The ideal transfer of energy occurs when a shorter segment of wire is applied to the sphincter tissue, and therefore, one must select an optimal length that allows adequate entry into the papilla while maintaining the proper transfer of energy to effectively cut. The authors favor the use of a 30-mm cutting wire.

Finally, multilumen sphincterotomes have been developed, providing a major advance. With double-lumen sphincterotomes, contrast is injected in the second lumen, which also functions as a port for guide-wire insertion. The triple-lumen variety allows contrast to be injected without removal of the guide wire.

Guide wires

Wires commonly used for sphincterotomy include the inexpensive Teflon coated guide wire, the basic Teflon sheathed wire (glide wire), and other Teflon sheathed wires (including the Zebra, Visi-Glide Jaguar, Hydra-Jag wires, and Metro wires). Teflon-sheathed wires are preferred to Teflon-coated wires because they may be less likely to short-circuit. [1] A theoretical concern exists regarding metal-core guide wires, in that they have the potential to produce unacceptably high current levels when damaged. [2] However, no convincing evidence has shown that non–wire-guided sphincterotomy is safer than wire-guided sphincterotomy. [3]

Electrosurgical generators

In order to perform sphincterotomy, an electrical current must be applied to the diathermy wire. This is achieved through a standard electrosurgical cautery generator. High-frequency current is required for sphincterotomy. This may be applied as either pure cut, pure coagulation, or a combination of the two. Most endoscopists choose a blend of the two because pure cut or pure coagulation alone may increase the risk of pancreatitis or a higher rate of bleeding, respectively.

Conventional generators

Conventional electrosurgical units (ESUs) use constant wattage. Variations in voltage from these devices may lead to complications, in that voltage is the primary determinant of thermal damage. Before going further, reviewing Ohm’s law is necessary. Ohm's law states the following:

  • Power = Voltage × current (P = V × C)

and

  • Current = Voltage/resistance (C = V/r)

Therefore,

  • P = V × V/r

or

  • V 2 = r × P

The ESUs function using constant power. As the wire begins to coagulate tissue, the tissue resistance will rise. From the equations above, it is important to note the direct relation between resistance and voltage (ie, as resistance rises, so will voltage). The units may thus deliver low voltage at low resistance and high voltage at high resistance. By bowing the sphincterotome, higher amounts of voltage are applied by creating tension. Once the wire breaks through, there is a short period during which the wire is cutting through low resistance tissue at high voltage, and this may lead to a "runaway cut."

Excessive thermal injury may occur. As illustrated by the aforementioned equations, current is equal to voltage divided by resistance; thus, resistance is inversely proportional to current, whereas voltage is directly proportional. The current level must be high at the start in order to ensure the necessary electrical arcs to cut tissue. As the cut continues, the current should decrease. Unfortunately, with conventional units, the voltage variation, which is unavoidable, can cause excessive coagulation leading to thermal injury.

A randomized prospective study found that a pure-cut current was associated with a lower frequency of pancreatitis than a blend current was. [4] No difference in the relative risk of bleeding was reported, possibly because of an insufficient number of patients studied.

ERBE generators

Unlike conventional ESUs, the ERBE unit uses constant voltage rather than constant wattage. By using constant voltage, these units disallow fluxes in voltage based on tissue impedance. Thus, the ERBE units will deliver more predictable and reproducible cutting effects with less overall thermal injury.

The energy is delivered with fractionated, intermittent pulses of current. This allows cutting with periods of hemostasis. The generator will automatically shut on and off, which maintains the cut in short stages. It has thus been hypothesized that this so-called endocut mode will lead to a lower incidence of bleeding as well as pancreatitis, because rapid cutting and excessive coagulation are decreased, respectively. [5]

In review of the literature, several studies suggest an advantage of ERBE generators over conventional generators. [6, 7] In a randomized study involving 100 patients, the authors demonstrated a decreased risk of bleeding as compared to conventional units. However, no clear difference existed in the incision length or risk of pancreatitis. [6]

One large study involved 2711 consecutive sphincterotomies. Specifically, the authors compared 1218 sphincterotomies using the Valleylab conventional generator and 1091 sphincterotomies using the ERBE generator. [8] They found an increase in bleeding using the Valleylab generator; however, this was endoscopically observed. They did not find a significant difference in clinically apparent bleeding. Again, no difference in pancreatitis between groups was discovered.

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Patient Preparation

With a skilled nurse or anesthesiologist present, sedation is provided with a combination of meperidine, fentanyl, midazolam, or propofol. Vital signs, including blood pressure, heart rate, and pulse oximetry, are monitored throughout the procedure.

Endoscopic retrograde cholangiopancreatography is generally performed with the patient prone or semiprone.

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