Emerging Technology List

Document Sample
Emerging Technology List Powered By Docstoc
					Emerging Technology List                                                      CANADIAN COORDINATING
                                                                                   OFFICE FOR HEALTH
WATER JET SYSTEMS            FOR   SURGICAL DISSECTION                        TECHNOLOGY ASSESSMENT
AND RESECTION
                                                                                      NO. 19     JANUARY 2004

        Technology:     Cutting with a high pressure stream of water has been used in industry for years. A
                        niche has since been found for this technology in medical procedures such as wound
                        débridement and thrombectomy; in arthroscopic and spinal surgery; in plastic
                        surgery such as liposuction and tattoo removal; in endoscopic sinus surgery; and in
                        ophthalmology. Papachristou and Barters first described the use of water jet surgical
                        dissection in 1982,1 when they used a jet of saline from an agricultural sprayer to
                        perform liver resections in four patients. They concluded that the use of the water jet
                        reduced blood loss during surgery. This summary focuses on the use of water jet
                        systems in the resection of organs such as the liver, gallbladder, kidneys and brain.

     Manufacturer:          Helix Hydro-Jet® (Andreas Pein Medizintechnik GmbH, Germany; ERBE
                            Elektromedizin GmbH / ERBE USA Incorporated hold global distribution rights
                            for the Helix Hydro-Jet)
                            VersaJet Hydrosurgery System (HydroCision Inc., US)
                            Handy-jet™ (Saphir Medical, France)
                            Hepatotom (Meditech, Switzerland)
                            Liquitom™ (Medaxis, Ammann-Technik AG, Switzerland)
                            Parenchimotom 01 (TOSA, Bulgaria).

           Purpose:     Controlling bleeding during and after surgery involving solid organs is a concern.2
                        Water jet dissecting systems allows for more selective cutting through organ tissue,
                        with less surgical trauma and blood loss.3

Current Regulatory      Health Canada licensed the Helix Hydro-Jet system in December 2001. The intended
           Status:      use of the device is for the selective dissection of soft tissues using pressurized saline
                        (Kathleen Savage, Health Canada, Ottawa: personal communication, 2003 July 16).
                        The US Food and Drug Administration 510(k) authorization for the Helix Hydro-Jet
                        defines the intended use for the device as “… cutting and dissection of soft tissue
                        such as the liver, kidney, etc. within the abdomen, including Total Mesorectal
                        Excision (TME), in open as well as laparoscopic surgery.”4

                        The VersaJet Hydrosurgery System (HydroCision, Inc.) was licensed by Health
                        Canada in July 2002 for use in wound and soft tissue débridement, and cleansing of
                        the surgical site (Kathleen Savage, Health Canada, Ottawa: personal communication,
                        2003 July 16). According to the manufacturer, the Canadian and US Food and Drug
                        Administration’s (FDA) authorizations for the VersaJet have recently been amended
                        to include the following indications: “… cutting, resection and removal of tissue,
                        contaminants or fluids from the wound or surgical site. Applications include general,
                        plastic, orthopaedic, trauma and vascular surgery” (James H. Hill, HydroCision Inc.,
                        Andover (MA): personal communication, 2003 July 17). Although the expanded
                        licensing authorizations include general surgery, the VersaJet’s primary application to
                        date has been in surgical débridement. Clinical studies of the system for organ resec-
                        tion are planned, but are not yet underway (James H. Hill, HydroCision Inc.,
                        Andover (MA): personal communication, 2003 October 6).


              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                      CANADIAN COORDINATING
                                                                                   OFFICE FOR HEALTH
WATER JET SYSTEMS            FOR   SURGICAL DISSECTION                        TECHNOLOGY ASSESSMENT

AND RESECTION


                        Several other commercial water jet dissecting systems intended for use in surgical
                        resection are available in Europe but are not licensed in Canada.

        Description:    Water jet systems use a fine stream of high pressure saline solution to cut through
                        tissue. Adjustments to the level of pressure allow the surgeon to selectively cut
                        through organ parenchyma, but not other structures, such as major blood vessels,
                        ducts or lymph vessels. These devices often include an aspiration tube to remove
                        tissue debris and fluid as the cutting occurs. As a UK review of dissection techniques
                        in laparoscopic surgery explains: “The advantages of water-jet cutting include
                        simplicity of the device, low maintenance cost, clean cutting and reproducibility of
                        the depth of the cut depending on the energy of the coherent water-jet.”5 The
                        mechanics used to create the water jet differ between the systems.

               Cost:    The Helix Hydro-Jet system costs C$179,900. The disposable applicators used for
                        different surgical procedures range in cost depending on their configuration and
                        size. For example, a box of 10 applicators in the most commonly used size costs
                        C$4,779.28 (Bill Roberts, AMT Electrosurgery, Kitchener (ON): personal communi-
                        cation, 2003 October 3).

                        The VersaJet Hydrosurgery System Power Console costs US$9,500 and the VersaJet
                        Disposable Handpiece Assemblies cost US$395 each. The VersaJet uses regular
                        sterile saline irrigant bags for the fluid supply (James H. Hill, HydroCision Inc.,
                        Andover (MA): personal communication, 2003 July 18).

          Evidence:     Most of the studies of water jet dissection have been done in Europe and Japan, so
                        many reports have been published in languages other than English. This summary
                        reviews only papers published in English or those with English abstracts. In general,
                        the studies are small, uncontrolled series that have looked at the use of this technology
                        in liver or hepatobiliary surgery and in open and laparoscopic surgery. Researchers
                        have also investigated the use of water jet systems in brain surgery. The larger
                        published studies for indications involving the brain and the organs of the abdomen
                        are summarized here.

                        Gallbladder

                        A recent randomized controlled trial of 80 patients compared the use of water jet
                        dissection (Helix Hydro-Jet) with conventional dissection in laparoscopic cholecys-
                        tectomy.6 Complication rates were reduced when the water jet was used. In particular,
                        gallbladder perforation occurred in 15% (n=6/40) of the water jet procedures, com-
                        pared with 30% (n=12/40) of the conventional dissections. Liver laceration requiring
                        the use of hemostatic agents to control bleeding occurred in 10% of the conventional
                        procedures (n=4), but in none of the water jet procedures. Use of the water jet
                        reduced dissection time, but not significantly.




              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                     CANADIAN COORDINATING
                                                                                  OFFICE FOR HEALTH
WATER JET SYSTEMS            FOR   SURGICAL DISSECTION                       TECHNOLOGY ASSESSMENT

AND RESECTION


                        The authors explained that many of the complications associated with laparoscopic
                        cholecystectomy occurred when the operative field was “obscured by hemorrhage
                        and adhesions from previous operations or the presence of acute inflammation…”
                        The tissue selectivity of the water jet reduced bleeding and the continuous water
                        flow helped to provide a clear operative field for the surgeon, although the field may
                        be obscured by the spray of the saline solution. The learning curve for using the
                        water jet was short. Though the study did not include a formal cost analysis, the
                        authors believed that this technology would increase surgical costs because of the
                        costs of the system and of the disposables. Whether overall costs might be reduced
                        through decreased complication rates is yet to be determined. Expanded use of the
                        technology for surgical procedures may decrease the costs involved.

                        Kidneys

                        Basting et al. reported on their use of the Helix Hydro-Jet in 24 patients who under-
                        went open surgery for conditions such as renal-cell cancer (partial nephrectomy) and
                        kidney stones (nephrolithotomy).7 Histologic analyses revealed that the water jet pro-
                        duced a sharp dissection line, with vacuolization of 100 µm to 300 µm; and reduced
                        trauma to adjacent tissue in comparison with thermal methods of dissection (electric
                        cautery or laser). The water jet dissections lasted between 14 and 35 minutes, with
                        an average blood loss of 60 mL. The length of hospital stay was similar to that for
                        other kidney surgeries − an average of 10.1 days. No major complications were
                        reported during the follow-up period of two to 17 months.

                        Liver

                        In the early 1990s, Baer et al. published several studies on the use of a high pressure
                        water jet system (the Hepatom or Hepatotom) in liver surgery.2,8-10 The most recent
                        paper from this group compared 67 resections for liver tumours.2 Manual separation
                        of the tissue (finger fracture technique) was used for 51 patients and water jet dissec-
                        tion was used for 16 patients. Four complications were reported in the water jet
                        group: one patient had a biliary fistula and three patients required treatment for post-
                        operative intra-abdominal fluid collection and infection. Two of these three patients
                        had preoperative conditions that may have predisposed them to these complications.
                        Though this study found no significant differences in operating times, the authors
                        reported a significant decrease in the need for blood transfusion in the water jet
                        group (a mean of 2.0 units) compared with the finger fracture group (a mean of 5.2
                        units).

                        Rau et al. compared laparoscopic liver resection using water jet systems (Jet-Cutter
                        and Helix Hydro-Jet) in 17 patients, with a matched pair control group of patients
                        who underwent conventional liver resection during the same period.11 The operating
                        time was significantly shorter with the conventional surgery. Though blood loss was
                        less in the laparoscopic group, it was not significantly reduced. The main advantage




              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                     CANADIAN COORDINATING
                                                                                  OFFICE FOR HEALTH
WATER JET SYSTEMS            FOR   SURGICAL DISSECTION                       TECHNOLOGY ASSESSMENT

AND RESECTION


                        seemed to be the reduced length of hospital stay -7.8±8.2 days in the laparoscopic
                        group and 11.6±12.8 days in the conventional surgery group. However, this is likely
                        due to the use of the laparoscopic procedure, rather than to the use of water jet
                        dissection. The authors concluded that the water jet permitted more selective dissec-
                        tion of the liver parenchyma.

                        In an earlier paper, Rau et al. compared liver resections in 116 patients using three
                        techniques: blunt dissection (n=61), the cavitational ultrasonic surgical aspirator
                        (CUSA®) (n=28) and the Jet-Cutter (n=27).12 The authors correlated several out-
                        comes per area of liver surface resected. They found that the amount of blood loss
                        per area of resected liver surface was lower with water jet dissection than with either
                        of the other two methods. The number of blood units transfused (per cm2 of liver
                        resected) was also reduced with water jet dissection (0.026±0.014 mL) compared
                        with CUSA (0.079±0.145 mL) and blunt dissection (0.066±0.039 mL). Liver hilus
                        clamping to reduce blood loss was performed in 60% of the patients in the blunt dis-
                        section group, 82% of the CUSA patients and 65% of those in the water jet group.
                        The duration of hilus clamping and resection relative to the area of liver resected
                        was significantly shorter in the water jet group. Laboratory measures of liver tissue
                        trauma did not show a significant difference among the three methods.

                        In another study by Rau et al., 61 patients undergoing liver resection were random-
                        ized to receive resection with either CUSA (n=30) or the Jet-Cutter (n=31).13 The
                        time for resections using the water jet was significantly shorter (28±11 minutes)
                        compared with the CUSA (46±19 minutes). The duration of liver ischemia was also
                        reduced: water jet (29±12 minutes) versus CUSA (39±16 minutes). The need for
                        blood transfusion was significantly less with the water jet dissection (a mean of 1.5
                        units) versus the CUSA (a mean of 2.5 units).

                        Few adverse events have been associated with the use of water jet dissection systems.
                        An early case report of possible venous air embolism in a patient undergoing liver
                        resection with a water jet (Hepatatom) may have been due to the positioning of the
                        patient during surgery, rather than to the use of the water jet.14,15

                        Mesorectal excision

                        An uncontrolled study involving 30 patients with rectal cancer found that water jet
                        dissection (Helix Hydro-Jet) allowed removal of the mesorectum from the pelvis
                        while preserving hypogastric nerves and resulting in less postoperative bladder
                        dysfunction. The authors suggested that if the saline solution used in the water jet
                        is replaced with a cytotoxic solution, this might provide an additional prophylactic
                        measure against local recurrence of cancer.16

                        Neurological procedures

                        Piek et al. reported on the use of water jet dissection (Helix Hydro-Jet and an earlier
                        version of this device, the Müritz 1000) in neurological procedures.17 Their study


              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                       CANADIAN COORDINATING
                                                                                    OFFICE FOR HEALTH
WATER JET SYSTEMS             FOR   SURGICAL DISSECTION                        TECHNOLOGY ASSESSMENT

AND RESECTION


                         included 35 patients with brain tumours (n=27), epilepsy (n=8) and internal carotid
                         artery stenosis (n=1). The water jet’s pressure was adjusted to suit the different levels
                         of cutting needed for different conditions. No complications due to the use of the
                         water jet were reported. The investigators found that the device was more useful in
                         some procedures than in others. For example, in patients with gliomas, the water jet
                         was particularly useful in the dissection of well vascularized tumours − dissecting
                         and aspirating the tumour while preserving the blood vessels. These were then
                         coagulated, causing minimal bleeding. In patients with firm, well defined metastatic
                         tumours, the water jet facilitated dissection of the tumours and identification of the
                         tumour-supplying blood vessels for subsequent coagulation with minimal blood loss.
                         With lower pressure levels, the water jet enabled resection of the brain tissue in
                         patients with epilepsy, while the blood vessels were preserved. None of the epilepsy
                         patients experienced postoperative brain edema, possibly because the water jet
                         caused less surgical trauma. For conditions such as certain types of meningiomas, the
                         water jet was not found to be useful, though the authors cautioned that the number
                         of patients was small and that the results should be considered preliminary. In the
                         patient with internal carotid artery stenosis, the water jet offered no advantage over
                         microsurgical resection. Piek et al. concluded that the water jet may facilitate resec-
                         tion in certain neurological procedures with less intraoperative blood loss, a reduced
                         risk of postoperative edema and no increase in duration of the surgery.

                         In a recent paper, the same authors reported their experience with water jet resection
                         of brain metastases in 10 patients.18 They concluded that “… the separation of firm,
                         clearly demarcated brain metastases from the brain parenchyma is easily and accu-
                         rately achieved with conventional methods. Thus at present, we do not see an indica-
                         tion for the application of the [water jet] instrument under these conditions. In con-
                         trast, the water jet device appears to be particularly helpful in the separation of soft,
                         poorly demarcated brain metastases from the surrounding brain parenchyma. This
                         separation remains rather challenging with conventional methods, often a plane
                         between tumour and adjacent parenchyma is difficult to establish, and tumour rem-
                         nants causing early recurrences are left in situ. Based on the present results in six
                         such tumours, the water jet enables precise and accurate tumour separation from the
                         brain leaving the adjacent brain intact.”

                         The authors concluded that the water jet will be useful in certain neurological proce-
                         dures, but that further studies were needed to determine where it offered advantages
                         over conventional methods. The potential for increased risk of infection or tumour
                         seeding due to the use of the water jet also needed further investigation, though the
                         authors found no evidence of these.

Available Alternative    Various tools and techniques are used in surgical dissection of organ tissue. These
       Technologies:     include instruments such as scalpels and scissors, ultrasonic cutting and coagulating
                         systems, such as the Harmonic Scalpel® or the cavitational ultrasonic surgical aspira-
                         tor (CUSA®), electrosurgical and laser systems.5 Blunt dissection, where the tissue is




               The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
  is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                              CANADIAN COORDINATING
                                                                                           OFFICE FOR HEALTH
WATER JET SYSTEMS             FOR    SURGICAL DISSECTION                              TECHNOLOGY ASSESSMENT

AND RESECTION


                        torn apart, rather than cut, may also be used. For example, in liver surgery, the “fin-
                        ger fracture technique” is used to separate the parenchyma (tissue) manually. Some
                        devices coagulate and cut. Unlike some cutting devices, water jet systems cause only
                        a slight rise in temperature, thereby minimizing thermal damage to tissue.19 This may
                        be important when conducting surgery on brain or neural structures.7

      Commentary:       There is little evidence on the use of some commercially available water jet systems
                        in surgical resection and there are no published studies that compare the performance
                        of different systems.

                        Many of the earliest published studies used first generation or prototype devices.20-24
                        It is difficult to determine from more recent studies whether initial problems with
                        these devices, including spray and the formation of air bubbles obscuring vision in
                        the surgical field; concerns about possible contamination of the operating field; and
                        concerns about tumour seeding, have been resolved.

                        An expansion of uses for water jet dissecting systems is likely. This may allow more
                        cost-effective use of these devices.6 A 2002 press release from ERBE USA notes that
                        further studies of the Helix Hydro-Jet in living donor liver transplantation, nerve-
                        sparing retropubic radical prostatectomy and cancer-related procedures are underway
                        in the United States.25

                        The evidence indicates that the use of water jet dissection can reduce blood loss and
                        transfusion requirements. In some procedures, resection time and the period of nor-
                        mothermic ischemia can be reduced. The learning curve for this technology seems to
                        be relatively short. More studies are needed to determine whether water jet resection
                        in cancer patients poses a risk of tumour reseeding. The published evidence, mainly
                        from older reports of small, uncontrolled studies, supports the use of the water jet in
                        reducing blood loss and surgical trauma in liver surgery. Fewer studies have been
                        published on the use of water jets in kidney surgery, though it seems to offer similar
                        benefits.26 The recent randomized trial by Shekarriz et al. indicates that water jet
                        dissection may offer advantages over conventional laparoscopic cholecystectomy, as
                        it may significantly reduce associated complications and blood loss.6

        References:     1.   Papachristou DN, Barters R. Resection of the liver with a water jet. Br J Surg 1982;69(2):93-4.
                        2.   Baer HU, Stain SC, Guastella T, Maddern GJ, Blumgart LH. Hepatic resection using a water jet
                             dissector. HPB Surg 1993;6(3):189-96.
                        3.   Penchev RD, Kjossev KT, Losanoff JE. Application of a new water jet apparatus in open hepato-
                             biliary surgery: hepatic resection, cholecystectomy, common bile duct lavage. Int Surg
                             1997;82(2):182-6.
                        4.   Center for Devices and Radiological Health, U.S. Food and Drug Administration. 510(k)
                             summary: Helix Hydro-Jet (K022613). Rockville (MD): The Center; 2002. Available:
                             http://www.fda.gov/cdrh/pdf2/k022613.pdf (accessed 2003 Jul 15).
                        5.   Shimi SM. Dissection techniques in laparoscopic surgery: a review. J R Coll Surg Edinb
                             1995;40(4):249-59.




              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                               CANADIAN COORDINATING
                                                                                            OFFICE FOR HEALTH
WATER JET SYSTEMS             FOR    SURGICAL DISSECTION                               TECHNOLOGY ASSESSMENT

AND RESECTION


                        6.   Shekarriz H, Shekarriz B, Kujath P, Eckmann C, Burk C, Comman A, et al. Hydro-Jet-assisted
                             laparoscopic cholecystectomy: a prospective randomized clinical study. Surgery 2003;133(6):635-
                             40.
                        7.   Basting RF, Djakovic N, Widmann P. Use of water jet resection in organ-sparing kidney surgery.
                             J Endourol 2000;14(6):501-5.
                        8.   Baer HU, Maddern GJ, Blumgart LH. New water-jet dissector: initial experience in hepatic sur-
                             gery. Br J Surg 1991;78(4):502-3.
                        9.   Baer HU, Maddern GJ, Blumgart LH. Hepatic surgery facilitated by a new jet dissector. HPB Surg
                             1991;4(2):137-44.
                        10. Baer HU, Maddern GJ, Dennison AR, Blumgart LH. Water-jet dissection in hepatic surgery.
                            Minim Invasive Ther 1992;(1):169-72.
                        11. Rau HG, Buttler E, Meyer G, Schardey HM, Schildberg FW. Laparoscopic liver resection com-
                            pared with conventional partial hepatectomy--a prospective analysis. Hepatogastroenterology
                            1998;45(24):2333-8.
                        12. Rau HG, Schardey HM, Buttler E, Reuter C, Cohnert TU, Schildberg FW. A comparison of differ-
                            ent techniques for liver resection: blunt dissection, ultrasonic aspirator and jet-cutter. Eur J Surg
                            Oncol 1995;21(2):183-7.
                        13. Rau HG, Wichmann MW, Schinkel S, Buttler E, Pickelmann S, Schauer R, et al. Surgical tech-
                            niques in hepatic resections: Ultrasonic aspirator versus Jet-Cutter. A prospective randomized clin-
                            ical trial [in German]. Zentralbl Chir 2001;126(8):586-90.
                        14. Smith JA. Possible venous air embolism with a new water jet dissector. Br J Anaesth
                            1993;70(4):466-7.
                        15. Baer HU, Blumgart LH. Venous air embolism with a water jet dissector. Br J Anaesth
                            1993;71(6):921.
                        16. Kockerling F, Yildirim C, Scheuerlein H. Total mesorectal excision in rectal carcinoma using the
                            water jet technique. Optimal radicality, maximum autonomic nerve preservation. In: Bruch H-P,
                            Kockerling F, Bouchard R, Schug-Pab C, editors. New aspects of high technology in medicine.
                            Bologna, Italy: Monduzzi Editore; 2000.
                        17. Piek J, Oertel J, Gaab MR. Waterjet dissection in neurosurgical procedures: clinical results in 35
                            patients. J Neurosurg 2002;96(4):690-6.
                        18. Oertel J, Gaab MR, Piek J. Waterjet resection of brain metastases - first clinical results with 10
                            patients. Eur J Surg Oncol 2003;29(4):407-14.
                        19. New cutting technologies in surgery: Durham, 19th April 1999. York, UK: Institute of Physics
                            and Engineering in Medicine; 2000. Available:
                            http://www.ipem.org.uk/sigs/etsig/meetings/new_cutting_technologies.html (accessed 2003
                            May 6).
                        20. Une Y, Uchino J, Horie T, Sato Y, Ogasawara K, Kakita A, et al. Liver resection using a water jet.
                            Cancer Chemother Pharmacol 1989;23 Suppl:S74-77.
                        21. Hata Y, Sasaki F, Takahashi H, Ohkawa Y, Taguchi K, Une Y, et al. Liver resection in children,
                            using a water-jet. J Pediatr Surg 1994;29(5):648-50.
                        22. Persson BG, Jeppsson B, Tranberg KG, Roslund K, Bengmark S. Transection of the liver with a
                            water jet. Surg Gynecol Obstet 1989;168(3):267-8.
                        23. Jeppsson B. Liver dissection in hepatic surgery: ultrasound vs water jet vs suction knife.
                            Hepatology 1990;11(3):509-10.




              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)
Emerging Technology List                                                             CANADIAN COORDINATING
                                                                                          OFFICE FOR HEALTH
WATER JET SYSTEMS            FOR     SURGICAL DISSECTION                             TECHNOLOGY ASSESSMENT

AND RESECTION


                        24. Cuschieri A. Experimental evaluation of water-jet dissection in endoscopic surgery. Endosc Surg
                            Allied Technol 1994;2(3-4):202-4.
                        25. ERBE USA, Inc. will formally launch the HELIX HYDROJET in September, 2002 [press release].
                            Marietta (GA): ERBE USA; 2002 Sep 5. Available: http://www.erbe-
                            usa.com/newserbe/000009.asp (accessed 2003 May 5).
                        26. Ogan K, Cadeddu JA. Minimally invasive management of the small renal tumor: review of
                            laparoscopic partial nephrectomy and ablative techniques. J Endourol 2002;16(9):635-43.




                         CCOHTA would like to thank Professor Guy Maddern, surgical director, Australian Safety and
                         Efficacy Register of New Interventional Procedures - Surgical (ASERNIP-S), for his thoughtful
                                                   review of an earlier draft of this summary.


                                       This summary was prepared by Leigh-Ann Topfer, MLS; CCOHTA.

                         This series highlights medical technologies that are not yet in widespread use in Canada and that
                          may have a significant impact on health care. The contents are based on information from early
                          experience with the technology; however, further evidence may become available in the future.
                         These summaries are not intended to replace professional medical advice. They are compiled as
                             an information service for those involved in planning and providing health care in Canada.
                                            These summaries have not been externally peer reviewed.

                                                          ISSN 1499-108X (online only)



              The Canadian Coordinating Office for Health Technology Assessment (CCOHTA)
 is a non-profit organization funded by the federal, provincial and territorial governments. (www.ccohta.ca)

				
DOCUMENT INFO