GB2488994A - Surgical Training Model - Google Patents

Abstract

The present invention relates to a surgical training model for laser surgical procedures, wherein the model comprises a fabricated multiple layer structure having at least one layer formed of a material selected to be susceptible being cut by application of light at a predetermined wavelength. In a preferred embodiment, the model represents a prostate gland and comprises first and second layers selected to have different susceptibilities to a laser operating at 2100nm. The first layer corresponds to abnormal tissue and the second represents an outer layer, both model layers being fabricated from foamed polyurethane having different densities. The model may also comprise a representation of a bladder.

Description

SURGICAL TRAINING MODELS

The present invention relates to surgical training models. In particular, it relates to a model for use in training surgeons in laser surgical techniques, particularly in prostate surgery.

The prostate is a small gland located under a man's bladder and around his urethra.

The prostate can become enlarged with age, causing problems with passing urine due to pressure on the urethra. This condition is called benign prostatic obstruction (BPO).

The standard surgical treatment for BPO is to cut away the middle of the enlarged prostate, in an operation known as transurethral resection of the prostate (TURP).

This operation is performed under anaesthetic, using a specially designed telescope inserted through the penis. Electric current is used to remove the enlarged middle part of the prostate in small pieces. Afterwards, a small tube (catheter) is inserted into the bladder for two or three days. Once any bleeding settles, the catheter is removed.

Most patients are in hospital for four or five days. The risks of TURP are mainly related to bleeding, and approximately 5% of patients will require a blood transfusion More recently, a holmium:YAG laser prostatectomy technique has been developed.

Holmium Laser Enucleation of the Prostate (HoLEP) is a similar procedure to TURP in that the central obstructing part of the prostate is removed using a telescope down the penis under anaesthetic. Unlike TURP, the prostate is removed in large pieces, which are then broken up within the bladder before removal. More tissue can be removed with HoLEP than with TURP and there is much less bleeding, as the laser seals blood vessels as the operation proceeds. The incidence of blood transfusions is thereby reduced to less than 1%, and this also means that the catheter can generally be removed the day after surgery. Hospital stay is thereby reduced, compared with TURP.

The holmium: YAG laser for prostate surgery is a pulsed solid-state laser, producing a wavelength of 2lOOnm at an energy of 100W (2.OJ at 50Hz). The laser is particularly suitable for this type of surgery as the laser energy is strongly absorbed by water, so in an aqueous environment the energy is dissipated without effect. However, if the laser beam is in contact with tissue, in this case the prostate, simultaneous cuffing and coagulation occur. The tissue effect occurs over a distance of 0.2mm, with a heating effect only up to 2mm, allowing precise underwater cutting. At lower power levels, the laser is also very useful for breaking stones in the urinary tract.

Although the HoLEP techniques were developed in the early 1990s, take up of the procedure has been relatively slow. This is thought partly due to the laser being expensive, making start-up costs high, although running costs are low. Some consultants consider that having invested much time and effort into perfecting their TURP techniques they are reluctant to take on a new procedure, particularly as there is a perception that the procedure is difficuh to leam.

In 2010 the National Institute for Clinical Excellence (NICE) published an evidence-based review of the treatment of bladder outflow obstruction. Having considered all the available published evidence they concluded that the optimum surgical options were either conventional TURP or HoLEP. This has created a recent surge of interest in HoLEP and many consultant surgeons are now interested in leaning the technique.

The introduction of any new technique on a large scale is potentially problematic, as patient safety must not be jeopardised, especially if there is a leaning curve.

There is currently a commercially available plastic prostate model for the purpose of TURP training, produced by Limbs and Things Ltd. However, there is a no surgical training model for HoLEP. The present invention seeks to overcome this problem.

In its broadest sense, the present invention provides a surgical training model for laser surgical procedures, wherein the model comprises a multiple layer structure having at least one layer formed of a material selected to be susceptible being cut by application of light at a predetermined wavelengths.

Preferably, the model is a prostate model wherein the at least one layer is a first layer corresponding to a central abnormal tissue and a model further comprises a second layer, an outer or capsule layer.

Preferably, the second layer is formed of a material capable of being cut by light at the predetermined wavelength. More preferably, the first and second layers are selected to have differential susceptibilities to light at the predetermined wavelength, even more preferably, the first layer has a greater susceptibility to light at the predetermined wavelength than the second layer.

Advantageously, the predetermined wavelength is a wavelength strongly absorbed by water, especially about 2lOOnm.

Preferably, the second layer is formed of a material having a higher density than the first layer.

Advantageously, at least one of said first and second layers is formed of a polymeric material. Preferably, at least the first layer is formed of a foamed polymeric material.

Preferably, the first layer is formed of a foamed polymeric material having a density of 30-60 kg/m3, more preferably about 50 kg/m3.

Preferably, the second layer is formed of a foamed polymeric material having a density of 80-250 kg/m3; more preferably 120-200 kg/m3, even more preferably about kg/m3.

Suitably, the foamed polymeric material is a foamed polyurethane material.

The above and other aspects of the present invention will now be described in further detail, by way of example only.

An anatomically-accurate prostate model was moulded in a two-layer structure having an inner portion representing a central abnormal adenoma to represent the target to be enucleated and an outer portion representing the physiological outer capsule of the prostate. The inner portion was formed from FlexFoam-iT III, a foamed polyurethane polymer having a foamed density of 48 kg/m3. The outer portion was formed from FlexFoam-iT X, a foamed polyurethane polymer having a foamed density of 160 kg/m3. Both layers were coloured to simulate the natural colours of the prostate gland.

Polyurethane has the advantage of being capable of being cut by a laser at the wavelengths associated with holmium:YAG lasers, thereby providing the same charateristics in terms of interaction between the laser and both the model and surrounding water, as will be experienced in the surgical environment. The low density material, compared with body tissues, however, allows the use of a lower power laser. A 20W laser is suitable, compared with the 100W power required clinically. As a result, the laser which can be used for training can be powered from a conventional power supply rather than requiring the 32A power supply of a 100W laser. The legislative safety requirements are also considerably reduced, allowing training to be carried out at substantially any training site, rather than only at sites certified for operation of high power lasers.

In alternative models, the model is formed of animal tissues.

In use, the model is mounted within a water-containing rig to provide an authentic operating environment. A suitable rig (once made opaque to provide laser safety) is available from SAMED GmbH. Standard operating instruments can then be used, namely a conventional resectoscope. In-flow and out-flow of water can be via the cytoscope and optionally through ports in the rig.

The polyurethane foam can be moulded to provide an anatomically-accurate structure.

This is important as the clinical procedure uses anatomical landmarks for guidance.

The use of a two-layer structure in which the outer capsule is also responsive to the laser light means that the model will respond to inaccurate manipulation of the laser in the same way as the natural tissue.

A synthetic bladder can be attached to the model so that morcellation and removal of the enucleated prostate can also be simulated.

Claims (15)

1. Claims 1. A surgical training model for laser surgical procedures, wherein the model comprises a fabricated multiple layer structure having at least one layer formed of a material selected to be susceptible being cut by application of light at a predetermined wavelength.
2. 2. A model as claimed in claim 1 wherein the predetermined wavelength is a wavelength strongly absorbed by water.
3. 3. A model as claimed in claim 1 or claim 2 wherein the predetermined wavelength is about 2lOOnm.
4. 4. A model as claimed in any one of claims 1 to 3 in the form of a prostate model, wherein the at least one layer is a first layer corresponding to a central abnormal tissue and a model further comprises a second layer, an outer or capsule layer.
5. 5. A model as claimed in claim 4 wherein the second layer is formed of a material capable of being cut by light at the predetermined wavelength.
6. 6. A model as claimed in claim S wherein the first and second layers are selected to have differential susceptibilities to light at the predetermined wavelength.
7. 7. A model as claimed in claim 6 wherein the first layer has a greater susceptibility to light at the predetermined wavelength than the second layer.
8. 8. A model as claimed in any one of claims 4 to 7 wherein the second layer is formed of a material having a higher density than the first layer.
9. 9. A model as claimed in any one of claims 4 to 8 wherein the fabricated multiple layer structure is a synthetic structure.
10. 10. A model as claimed in any one of claims 4 to 9 wherein at least one of said first and second layers is formed of a polymeric material.
11. 11. A model as claimed in claim 10, wherein at least the first layer is formed of a foamed polymeric material.
12. 12. A model as claimed in claim 11 wherein the first layer is formed of a foamed polymeric material having a density of 30-60 kg/m3, preferably about 50 kg/m3.
13. 13. A model as claimed in claim 11 or claim 12, wherein the second layer is formed of a foamed polymeric material having a density of 80-25 0 kg/ni3; preferably 120-200 kg/m3, more preferably about 160 kg/m3.
14. 14. A model as claimed in any one of claims 11 to 13 wherein the foamed polymeric material is a foamed polyurethane material.
15. 15. A model as claimed in any one of claims 4 to 14 further comprising a bladder model.