Extracorporeal Shock Wave Lithotripsyin a NutshellChristian Chaussy, Geert Tailly, Bernd Forssmann, Christian Bohris, Andreas Lutz, Martine Tailly-Cusse, Thomas TaillyEdited by Christian Chaussy and Geert TaillyExtracorporeal Shock Wave Lithotripsyin a NutshellChristian Chaussy Geert Tailly Bernd Forssmann Christian Bohris Andreas Lutz Martine Tailly-Cusse Thomas Tailly Dornier MedTech Europe GmbHPublished byDornier MedTech Europe GmbHArgelsrieder Feld 782234 WesslingGermanyhttp://www.dornier.comPrinted by Dinauer GmbH, Munich, Germany4th edition, 2014Christian Chaussy Prof. of UrologyUniversity of Regensburg, Germanycgchaussy@gmail.comGeert G. Tailly, MD, FEBU Head of the Department of UrologyAZ Klina, Brasschaat, Belgiumgeert.tailly@klina.beBernd Forssmann, Dr. Herrsching, GermanyChristian Bohris, Dr.Project Leader, Dornier MedTech Systems GmbH, Wessling, GermanyAndreas Lutz, Dr.Program Manager, Dornier MedTech Systems GmbH, Wessling, GermanyMartine Tailly-Cusse Specialty nurse Endourology & ESWLAZ Klina, Brasschaat, BelgiumThomas Tailly, MDDepartment of Urology, UZ KU Leuven, BelgiumVContents1Introduction72Lithotripter design92.1Shock wave generator92.2Localization system102.3Patient positioning102.4Integrated endourology concept113Basics of shock wave physics133.1Shock wave generation143.1.1Electromagnetic143.1.2Electrohydraulic143.1.3Piezoelectric143.2Shock wave parameters153.2.1Pressure P+153.2.2Focus size163.2.3Penetration depth163.2.4Effective energy E12mm173.2.5Energy fux density173.3Energy dose concept183.4Stone breaking mechanisms193.4.1Hopkinson effect193.4.2Shear forces203.4.3Squeezing effect203.4.4Cavitation213.5Tissue effects224Indications234.1Renal stone treatment234.1.1General recommendation234.1.2Special recommendation for lower pole stones234.2Ureteral stones244.3Special indications244.3.1Paediatric urolithiasis254.3.2Obesity 254.3.3Renal anomalies 264.4Stone composition 265Contraindications27Contents6How to perform ESWL?296.1Device preparation296.2Pain management 306.3Patient preparation 316.4Positioning326.5Stone targeting336.5.1X-ray guided ESWL346.5.2Ultrasound guided ESWL356.6Coupling386.7Shock wave application treatment parameters406.7.1Kidney stones406.7.2Ureteral stones426.8Paediatric urolithiasis426.8.1Anesthesia426.8.2Paediatric positioning aid436.8.3Lung protection436.8.4Imaging436.8.5Adapted shock wave parameters447Follow-up457.1Stone clearance457.2Stone analysis prevention of new stone formation467.3Complications467.3.1Subcapsular haematoma467.3.2Septicaemia 477.4Long-term complications488Summary489Literature49VI1IntroductionFollowingextensiveresearchthatstartedasearlyasin1974,thefrst extra corporealshockwavelithotripsy(ESWL)treatmentofahumanwas performedonFebruary07,1980byChristianChaussy,DieterJochamand Bernd Forssmann using a prototype Dornier HM1 (Dornier Human Model 1, seeFig.1-1)lithotripter[1]. Thefrstserial Dornier HM3 (DornierHuman Model 3) was installed in 1983 at the Katharinen Hospital in Stuttgart and in March 1984 the frst Dornier HM3 in the US was installed at the Methodist Hospital in Indianapolis. The results with this new treatment modality were sosuccessful,thatitthoroughlyrevolutionizedmodernstonemanagement. A rapid expansion of indications encompassing urinary stones of all sizes at all levels of the urinary tract made ESWL the treatment of choice for almost any urolithiasis.Fig. 1-1: HM1 at the Munich University Hospital Grosshadern 71PrimarilyduetothehighcapitalinvestmentforaDornierHM3ESWL originally remained the privilege of high volume stone centers with urologists heavilytrainedinthepracticeofESWL.Withtheintroductionofless expensivesecondandthirdgenerationlithotriptersthepracticeofESWL becameavailabletomoreandalsosmallercenters.Thisrapidpropagation ofextracorporealshockwavelithotripsyineversmallercentersinevitably resulted in dilution of experience and poorer results with ESWL. As the newer lithotripters also proved easier to operate than the Dornier HM3, they were considered plug and play and proper training in ESWL more often than not was neglected leading to a further deterioration in results. As a consequence the pendulum swung in favour of endoscopic techniques (URS, RIRS, PNL). Although these techniques demand a high level of skill and expertise, these were and still are provided in extensive and intensive training programs. This is in sharp contrast to the often substandard training in ESWL, still the least invasive treatment modality for any urinary stone. With proper equipment, an understanding of the basic physics of shock waves and adequate training in the safe application of shock wave energy, results are excellent with minimal complications.InordertoachieveoptimaltreatmentresultswithESWL, anunderstandingoftheunderlyingphysicalmechanismsandaknowledge of the necessary treatment protocols are therefore essential. The purpose of thisbrochureistoinformtheuseraboutthephysicalprinciplesbehindthe technology and to offer practical guidance on performing ESWL.1Introduction182Lithotripter designAll lithotripters basically consist of three components: a shock wave generating system,alocalizationsystemforidentifyingandlocalizingthestoneanda positioning system used to position the stone in the shock wave focus, where the shock wave intensity is the highest. When the three components are used intherightcombination,thestonecanbefragmented.Nexttothesethree essentialsystems,additionalcomponentsforcontrolling,monitoringand documentation (See Fig. 2-1) are incorporated in most models. 2.1Shock wave generatorThe shock wave generator, the most important component of any lithotripter, generates the shock waves and aims them at the focus by means of a focussing unit, such as a lens. Water is necessary to effciently transfer the shock waves into the patient as it has acoustic properties similar to those of tissue. In the HM3, coupling between the generator and the tissue is achieved directly by means of a water bath in which the patient is placed. This coupling is ideal because there are no disturbing structures to inhibit the propagation of shock waves. In the new units, the shock waves are transferred into the patient via acouplingcushion.ForESWLtobesuccessfulthecouplingmustbeloss-free.Shockwaveenergyisakeyparameterinstonedisintegration,while energyfuxdensityrelatestothecauseofrenalsideeffects. Therefore,the new systems are optimized for high energy in order to deliver the maximum levelofenergytothestonewithminimaltissuetrauma.Thepenetration depths have been extended to 17 cm, which makes it possible to treat obese patients. Today,mostlithotriptersareequippedwithelectromagneticshock wave systems (detailed information is provided in chapter 3).9 2102.2Localization systemPrecise three-dimensional localization of the stone is essential for successful ESWL. Fluoroscopy is the preferred method for locating radiopaque stones in the upper urinary tract and is easily learned. However, it has the disadvantage that continuous observation is not possible because of the associated radiation exposure. Therefore, fragmentation cannot be monitored continuously. In the case of radio-lucent stones, additional measures, such as the use of contrast agents,arenecessary.Thefuoroscopyisperformedusinganisocentric C-armcontainingahigh-poweredtubeandtheimagingsystem,suchasa fat-paneldetector.ThisC-armcanbepivotedlongitudinallyororbitally around the shock wave focus in order to view the stone in two planes. The position of the stone can be accurately determined in three dimensions using this information.Ultrasound is a method that allows the stones to be localized without ionizing radiation,regardlessoftheircomposition.Thepositionofthestonein relation to the focus can be monitored and evaluated continuously. However, ultrasoundisonlysatisfactorywithstoneslocatedinthekidneyandinthe proximalanddistalareaoftheureter.Itrequiresarelativelylongtraining periodinordertoachievetheexperiencethatisneededforsuccessful ultrasound guided ESWL. Both imaging methods can be used simultaneously in most modern lithotripters. In outline localization, the ultrasonic transducer can be moved isocentrically about the focal point in order to set the optimal window for the image. When the ultrasonic transducer is localized in-line, it is located within the shock wave generator along the shock wave propagation axis.2.3Patient positioningIn order to achieve suffcient disintegration, the stone must frst be positioned precisely in the shock wave focus. This is accomplished by using an x-ray-transparent table on which the patient can be moved in all spatial axes. The tablecontainsopeningsthatmakeitpossibletocoupletheshockwave generator to the patient.2.2Localization system2Fig.2-1:ModernurologicalworkstationforESWLandendourology(DornierGemini). Shock wave unit (a), patient positioning system (b), X-ray localization system with C-arm (c), Flat Panel Detector (FPD) (d) and X-ray tube (e), isocentric ultrasonic localization arm (f).2.4Integrated endourology conceptModernstonemanagementisbasedonajudiciouscombinationand integration of ESWL and endoscopic techniques: the Integrated Endourology Concept.Therefore,modernlithotriptersaredesignedasmultifunctional urological workstations that provide optimal conditions for both ESWL and endourolgical procedures, such as URS, PNL, RIRS [2].112Lithotripter design21223Basics of shock wave physicsShock waves are acoustic waves. These waves consist of pressure and density variations, which propagate at medium-specifc velocities in media like water and soft tissue as well as in solid bodies such as bones and metals. Inthesimplestcase,anacousticwaveisaperiodicsinusoidaloscillation (See Fig. 3-1).Fig.3-1:Schematicillustrationofalongitudinalwave.Thecurverepresentspressureor density as a function of space. In a homogeneous medium the waves produce areas of periodic compressionanddecompression.Thisisillustratedbythedistributionofvolumeelements showing dense and expanded regions.Whentheoscillationislimitedtoashortdurationcomprisingonlyafew signal periods, it is called an acoustic pulse. Typical examples are diagnostic ultrasound pulses.Shock waves are very short acoustic pulses with very short rise times and a high peak pressure.For details on shock wave physics we recommend literature [3, 4].3 13143.1Shock wave generationFig. 3-2: Principles of shock wave generators used in lithotripters (See text for description). Left:Electro-MagneticShockwaveEmitter(EMSE).Centre:Electrohydraulicshockwave emitter. Right: Piezoelectric shock wave emitter.3.1.1 ElectromagneticThe main component of an electromagnetic shock wave source is the Electro-Magnetic Shock wave Emitter (EMSE). The EMSE is driven by a high voltage electric pulse that causes a rapid movement of the EMSEs membrane. This rapidforwardmovementofthemembranecreatesaplanaracousticpulse thatisfocusedbyanacousticlensandtransmittedtothepatientthrougha water-flled bellow.3.1.2 ElectrohydraulicThemaincomponentsofanelectrohydraulicshockwavegeneratorarethe electrode, which is also referred to as spark plug, and an ellipsoidal refector. The underwater spark gap discharge between the tips of the electrode causes rapid local vaporization to occur in the water, which generates a high-amplitude pressure pulse. To focus the initial radial wave, the electrode is located at the focal point F1 of the ellipsoidal refector. The shock wave is refected by the walls of the ellipsoid creating a focused shock wave in the focal zone F2.3.1.3 PiezoelectricPiezoelectric crystals expand rapidly when a high voltage electrical pulse is appliedtothem.Inpiezoelectricshockwavegenerators, alargenumberof piezoelectriccrystalsaresynchronouslyexcited,whichcreatesapressure wave. Focusing is accomplished by arranging the piezoelectric crystals in a spherical shape.3.1Shock wave generation33.2Shock wave parametersFig. 3-3 and Fig. 3-4 illustrate the pressure signal in the focus of a shock wave source. Ashockwaveischaracterizedbyaveryshortrisetimeandshort pulse duration followed by a negative pressure phase. A set of parameters is used to characterize a shock wave feld. 3.2.1 Pressure P+The maximum positive pressure is referred to as the positive peak pressure P+ and is measured in MPa. Typically the focal value varies between 30 and 120 MPa. The rise time ranges between 1 and 200 ns. The minimum negative pressureofthesucceedingtensilephaseistypicallybetween-4MPaand -15 MPa. Fig. 3-3: Shock wave pressure pulse as function of time measured in the shock wave focal zone F2.3Basics of shock wave physics3 15163.2.2 Focus sizeThefocussizeistheFull WidthatHalfMaximum(FWHM)ofthespatial pressuredistribution,alsoreferredtoasthe-6dBfocus.TheFWHMis thewidthofthespatialpressuredistributionat50%ofthepeakpressure (maximum of the curve). While this defnition makes sense in physical terms, considering it as the precise region at which stone disintegration is possible can be misleading. From Fig. 3-4 it is obvious that signifcant pressure is still present outside of the area defned by the focus size and that this pressure may also contribute to stone disintegration.Fig. 3-4: Curve illustrating the focus width (showing the -6 dB focus).3.2.3 Penetration depthThisisthedistancebetweenthecouplingsurfaceandthefocalspotofthe shock waves. The maximum penetration depth of lithotripters may vary.3.2Shock wave parameters33.2.4 Effective energy E12mmTheeffectiveenergyE12mm(alsoreferredtoasEeff)isameasureofthe energy per shock wave pulse in mJ that is transmitted through a circular area of 12 mm in diameter within the focus spot. (See Fig. 3-5). Fig. 3-5: Effective Energy E12mm.The blue circle represents the diameter of the cross section of a typical stone. The green arrow indicates the direction in which the shock wave travels. The total energy that passes through the circle is referred to as the effective energy.3.2.5 Energy fux densityTheenergyfuxdensityEDisameasureoftheenergyconcentration.Itis measured in mJ/mm2, i.e. energy per unit area.Infocussedshockwavesystems,theenergyremainsthesameasthewave travels through a decreasing area on its way to the focal zone. Thus the energy fux density increases and reaches its maximum at the focus (See Fig. 3-6).3Basics of shock wave physics3 1718Fig. 3-6: Energy fux density.The lower part of the illustration shows the lens (light red) of an EMSE system. The yellow coneindicatestheshockwavepath.Greencirclesindicatetheareatheshockwavepasses through while travelling from the lens surface to the focal region. As the distance from the lens increases, the area traversed by the shock wave gets smaller. Conservation of energy dictates that the energy density must increase and reach its maximum at the focal point.3.3Energy dose conceptWitheachshockwavepulseacertainamountofeffectiveenergyEeffis applied. The energy dose then is the sum of applied effective energy for all shock wave pulses during the course of a stone treatment. Assumingthatrampingisapplied,thetreatmentstartsatlowenergylevel with Eeff1. After a given number of pulses n1, the energy is increased in steps, e.g.withn2pulsesofEeff2,n3pulsesofEeff3,a.s.o.Thenenergydoseis calculated as follows:Edose(12mm) = n1 Eeff1 + n2 Eeff2 + n3 Eeff3 + Within a certain acceptable range the same effect on treatment outcome and side effects can be expected provided that the applied energy dose is the same.3.3Energy dose concept33.4Stone breaking mechanismsStone-breakingmechanismshavebeeninvestigatedsincetheearlydaysof medicalshockwaveresearch.Fourmajoreffectsthatcontributetostone disintegration have been identifed:Hopkinson effectShear forcesQuasistatic squeezingCavitationCavitation mainly contributes to the surface erosion of stones and fragments. Its other effects contribute to the cracking that breaks the stone into pieces. The Hopkinson effect, shear forces and quasistatic squeezing are caused by thedifferencesinthespeedofsoundintissueandinstones.Somebasic informationabouttheHopkinsoneffect,shearforcesandcavitationis provided in the following subsections.3.4.1 Hopkinson effectTheHopkinsoneffectoccursbecauseofarefectionoftheshockwaveat the rear surface of the stone. It causes the stone to break into large pieces. In analogy to light, acoustic waves are refected and diffracted at the transition from one medium to another. When a shock wave is passing through a stone, itispartiallyrefectedatthestonefrontandrearsurfaces.However,atthe rearsurfaceofthestone,i.e.thetransitionfromthemoredensetotheless dense medium, the refected pulse component is associated with a reversal of the peak amplitude of the shock wave. Therefore, a high amplitude negative pressure wave travels in the direction opposite to that of the original wave, inducing high tensile forces in the stone. (See Fig. 3-7 for illustration).193Basics of shock wave physics320Fig. 3-7: Hopkinson effect.The grey circle represents a stone. The incoming shock wave (1), travelling from left to right, is split at the front stone surface into a refected (2) and transmitted (3) component. At the rear stonesurface,theshockwave(3)isagainpartiallyrefected,resultinginahigh-amplitude negative pressure wave (4).3.4.2 Shear forcesShear forces are another effect caused by the different speeds of sound in stone and tissue. Inside the stone a shock wave travels faster than in surrounding tissue. A convergent wave is produced inside the stone, but outside the stone adivergentwaveiscreated. Thiscreatesstrongtensileforcesinthestone, which contribute to crack formation within the stone.3.4.3 Squeezing effectQuasistatic squeezing was postulated by Eisenmenger in 2001. Quasistatic squeezingisbelievedtooccurasaneffectofthefasterspeedofsound insidethestoneversusthatoutsidethestone. Whentheshockwaveenters the stone it moves faster than the wave outside the stone. This would create circumferential compressive forces outside the stone and tensile stress inside the stone, which might contribute to stone fragmentation.3.4Stone breaking mechanisms33.4.4 CavitationEveryshockwavepulsehasatrailingnegativepressurephase.Itstensile forcescreatemicrobubblesinliquidslikeurineorblood.Thesecavitation bubblesareunstableandcollapsewitharapidimplosion(SeeFig.3-8). Theassociatedliquidjetscauseapittingofadjacentstructureslikestones. Cavitation increases with shock wave frequency and intensity.Fig. 3-8: Image sequence of a solid target exposed to a shock wave propagating from left to right.Thesecondframeshowsindividualcavitationbubbleswithinthewaterandabubble clusteronthefaceofthetarget. Whereasthesinglecavitationbubblescollapsequiteearly, theclustergrowsfurtheruntilitcollapses,revealinganintermediatemushroom-likeshape (680 s).213Basics of shock wave physics3223.5Tissue effectsBasically all effects that contribute to stone disintegration may also contribute to tissue damage. Two major effects are discussed in this section.Cavitation, which may occur for example inside blood vessels or in the urine-flledcollectingsystemofthekidney,cancausevesselandparenchymal damage resulting in bleeding and haematomas. Recent literature shows that the risk of cavitation-induced renal damage increases with high shock wave frequenciesandexcessiveintensities.Whenashockwavepassesthrough tissueitmaystrikecavitationbubblescreatedbyapreviousshockwave pulse. This has two effects:The shock wave energy is partly blocked by the cavitation bubbles so that the stone is exposed to reduced shock wave energy (See Fig. 3-9).The shock wave interfering with cavitation bubbles can create forced bubble collapse, which increases the risk of side effects.Asaresult,stonedisintegrationisimpairedandtheriskofsideeffectsis increased.Gas-flledorgans,particularlythelung,areathighriskofseveretissue damage when exposed to shock waves. When shock waves reach the tissue/gasinterface,theyarerefected,andtherefectedshockwaveisreversed inpolarity(SeealsoHopkinsonEffect).Theresultingtensileforcesatthe interface can cause organ rupture (See Fig. 3-9).Fig. 3-9: Left: Blocking effect of a cavitation bubble feld. Cavitation bubbles within the shock wave path cause an attenuation of the shock wave. Compared to the undisturbed situation, the shock wave pressure amplitudes are lowered (See blue curves). Right: Refection at a tissue/air interface. The incoming shock wave (blue) is fully refected. Due to the transition from the positive pulse into a negative pulse this region is exposed to strong tensile forces.3.5Tissue effects34IndicationsESWL is a non-invasive treatment modality for stones in the entire urinary tract. With modern lithotripters all portions of the urinary tract are accessible.Major advantages of ESWL over other procedures are: It is the least invasive treatment modality for urolithiasis. In the majority of cases it does not require anaesthesia. Generally, analgosedation is used for pain management. ESWL is very safe with a very low risk of side effects and serious complications.Despite ESWLs potential as a universal method for stone treatment, selecting the right patients and stone locations is a prerequisite for success. For patients withnormalrenalanatomyandstoneslocatedintherenalpelvisandthe upper and middle calyx up to a size of 20 mm, shock wave lithotripsy is the preferred treatment modality.4.1Renal stone treatment4.1.1 General recommendationWith the introduction of the Dornier HM3 in the 1980s, ESWL became the treatment of choice for kidney stones. This is refected in current EAU and AUA Guidelines [5, 6]. For the removal of radiopaque (calcium) and cystine stones with a maximum diameter of 20 mm, ESWL is recommended as the frst-line therapy.4.1.2 Special recommendation for lower pole stonesFor lower calyx stones there is an ongoing debate about the effcacy of ESWL. Several clinical trials have shown that the stone-free rate after ESWL of lower calyx stones is worse than for stones in other parts of the renal system. In 1992, Sampaioetal.alreadyreportedthatanacutelowerpoleinfundibulopelvic angle,anarrowinfundibularwidth,andalonginfundibularlengthmay predict a decreased stone-free rate. However, Danuser et al. (2007) could not fndanysignifcantanatomicalinfuenceontheclearanceofdisintegrated stones from the lower calyx. In the lower pole study 1 by Albala et al. (2001) a cumulative stone-free rate of 37% for ESWL versus 95% for percutaneous nephrostolithotomy (PNL) was reported.23 424Ontheotherhand,Obeketal.(2001)andRiedleretal.(2003)reported cumulative stone-free rates of 63% and 65.5% for lower pole calculi treated with second- and third-generation lithotripters. Obek could not fnd signifcant differences in treatment outcomes for stones in lower, middle or upper calices. Pearle et al. (2005) compared ESWL and ureteroscopic lithotripsy (URS) for treatment of small lower pole stones. In a randomized multicenter study they couldnotfndasignifcantdifferenceinstone-freerates.ESWL,however, was associated with greater patient acceptance and shorter convalescence.Modernlithotripterswithelectromagneticorpiezoelectricshockwave sourcesmayresultinstone-freeratesthataresuperiortothe37%stone-freeratereportedinthelowerpolestudy1ifhigherretreatmentratesare accepted.Severalstudieshavedemonstratedthatthemostimportantfactor infuencing the treatment outcome is stone size. Therefore, ESWL should be the preferred treatment modality for lower pole renal stones up to a diameter of 10 mm. For lower pole stones 11-20 mm in size ESWL outcome is inferior to endoscopic stone removal. However, ESWL might be an option because of its non-invasive nature and the low risk of complications.Though clinical trials indicate that the anatomy of the lower pole collecting system might play a role in stone clearance and thus stone-free rate, it remains unclear which parameter is the best predictor for treatment success.4.2Ureteral stonesWhileURShasgainedsignifcantimportanceforthemanagementof ureteralstones,theadvantageofESWLforstonessmallerthan10mmis itsnon-invasiveness,avoidanceofgeneralorregionalanaesthesia,andthe low incidence of signifcant complications. In a series of 598 ureteral stone patients treated with ESWL, Tiselius et al. (2008) achieved a stone-free rate of more than 97% with an average number of 1.3 treatment sessions, a result that is comparable to the outcome of endoscopic stone removal.4.3Special indicationsSpecialattentionisneededinpaediatricandobesepatientsaswellasin patients with renal abnormalities.4.2Ureteral stones44.3.1 Paediatric urolithiasisForpaediatricpatientsESWLisasafeandeffectivetreatmentmethod.In spite of its small diameter, the ureter has a high transport capacity for stone fragments,whichexplainswhystone-freeratesforchildrenaresuperiorto those in adults. There is no evidence that ESWL causes irreversible functional or morphological changes.Therefore,ESWLremainsthetreatmentofchoiceforstonesinchildren. However,itisimportanttoadapttheESWLprotocoltothesmaller anatomical dimensions. The following recommendations may be helpful:A paediatric positioning device should be used to assure safe patient positioning.Lungshavetobeprotectedagainstshockwaveexposuretoavoid tissue damage.Radiationexposureshouldbeminimized;ifpossible,ultrasound localization should be used.Shock wave energy should be as low as possible.See section 6.8 for details.4.3.2 Obesity Overall, ESWL is challenging in morbidly obese patients due to diffculties withstonevisualizationandpositioning.Thecoincidenceofobesitywith large and hard stones is likely to result in poor stone clearance. However, in experienced hands, ESWL is a reasonable therapy option for obese patients with stones < 20 mm. Shock wave devices having a deeper penetration depth can also be expected to improve outcomes.Pareeketal.(2005)foundthataskin-to-stone-distance(SSD)exceeding 10cmwasassociatedwithESWLtreatmentfailure.Incontrast,Muozet al.(2003)reporteda3-monthsstone-freerateof72%andconcludedthat lithotripterpropertiesandoperatorexperiencewerethesecretofsuccess. SimilarresultswerefoundbyMezentsevetal.(2005).Inmorbidlyobese patients (BMI > 40 kg/m) an overall 3-months stone-free rate after ESWL of 73% was achieved. 254Indications426Inobesepatientsthemainproblemisthepropertargetingandfocussing ofthestones. Thereforelithotripterswithhighresolutionimagingsystems, versatile coupling of the therapy head above and under table, and above all a SW-source with a penetration depth of up to 17 cm are expected to yield better results.Experienced operators also use simple positioning tricks to improve targeting in obese patients.4.3.3 Renal anomalies Renalanomaliesareoftenassociatedwithanimpaireddrainageand consequentlyareducedclearanceofstonefragments.IntheirreviewSheir etal.(2003)reporteda72.2%stone-freerateafter3monthsinpatients with anomalous kidneys. Turna et al. (2007) concluded from a retrospective analysis of management of calyceal diverticular stones that ESWL is suitable to render most patients symptom-free with minimal complications despite a low stonefree rate of 21%.For patients with renal anomalies the treatment procedure should be chosen individually considering kidney function and location, stone size, availability of appropriate equipment and expertise of the performing urologist and even accepting multiple treatment.4.4Stone composition It is known that stone composition and internal stone structure are important characteristics that determine the hardness of urinary calculi and therefore the responsivenesstoshockwaves. Therehavebeennumerousattemptstouse non-contrastcomputedtomography(NCCT)topredictESWLsuccessrate based on Hounsfeld unit (HU) measurements. There is no consensus, though, as to which HU values will predict ESWL success or failure.Even hard concretions like brushite and cystine stones are not a contraindication for ESWL if the stone burden is small and the patient prefers a non-invasive therapy.4.4Stone composition45ContraindicationsSinceESWLwasfrstintroducedin1980,itsrangeofindicationsrapidly expanded to include most stones at all levels of the urinary tract. International EUA/ AUAGuidelines[5,6]considerESWLtobetheprimarytreatment modality for most stone types.Thefollowingconditionsareabsolutecontraindications,andpatientswho have them should be considered for alternative treatment modalities:PregnancyUntreated coagulation abnormalitiesContinued use of anticoagulants prior to ESWLPulmonary tissue in the shock wave pathTumour in the shock wave pathAneurysms in the shock wave pathPathological changes in the shock wave pathActive pyelonephritisPregnancyremainsanabsolutecontraindicationduetothepossibleuseof fuoroscopybutaboveallduetothepossibleadverseeffectsoftheshock wave on the foetus.Giventhatuntreatedcoagulationabnormalitiesdramaticallyincreasethe riskoflargeperirenalandsubcapsularhaematomas,theyareanabsolute contraindicationforESWL.Theinfuenceofmedicationscontaining acetylsalicylicacidisunderdiscussion.Mostoftheavailablepublications recommend a break of four to seven days.Untreated hypertension is considered a relative contraindication and should be regulated before treatment.27 52856How to perform ESWL?ThissectionprovidesgeneralpracticalguidelinesforESWL.Theorderof the various activities device preparation, pain therapy, patient preparation, positioning, stone targeting, coupling and shock wave application is based on the workfow of the ESWL treatment. This will facilitate implementation of the clinical process. All of these activities contribute in one way or another togoodstonedisintegrationcombinedwithlowtissueinjuryandpatient safety.Thischapteristheresultoflonglastingexperienceoftheauthors andothers[7-10].Mostpointsarealsoapplicablewhentreatingchildren. However, special aspects of paediatric ESWL are summarized in a separate section.6.1Device preparationWhentreatingapatient,itisimportanttobesurethatthelithotripterisin properworkingorder.Thealignmentoftheimagingsystems(X-rayand ultrasound) is especially critical and must be checked daily after the system is initially started. The target mark superimposed on the image must not deviate from the actual lithotripter focus. This would cause incorrect stone alignment andthusreduceddisintegrationandpossibletissueinjury.Manufacturers provide special test equipment and phantoms for these tests (See lithotripter user manual). The images obtained with the tests should be stored or printed out in order to document correct alignment. The coupling cushion and patient table must be clean in order to avoid cross-contaminations between patients. The lithotripter coupling cushion needs to be checked for possible air bubble inclusions. Any air that is present needs to be evacuated as described in the user manual.Check the status of the lithotripter.Check the alignment of the ultrasound andX-ray imaging systems.6 29306.2Pain management ESWL is a potentially painful procedure and suffcient analgesia is mandatory for good treatment results. Pain arising during ESWL is a multifactorial event. Ontheonehandcutaneoussuperfcialskinnociceptorsarestimulated,on the other hand visceral nociceptors in the renal capsule, periosteum, pleura, peritoneum and muscles are involved.Patients who experience pain tend to move voluntarily or involuntarily and show increased respiratory motion. Consequently, the target moves out of the shockwavefocusandthehitratedecreases. Thiscorrelateswithimpaired stone fragmentation and a subsequent impaired stone clearance. Additionally, paincanpreventtheplannedshockwavedosefrombeingapplied,i.e.the shock wave energy level and the number of pulses. It may also cause a rise in blood pressure, which may lead to more complications like a higher rate of kidney haematomas.Thepainishighlydependentontheshockwaveenergylevelapplied.Itis alsoincreasediftheskinisclosetotheshockwavefocus,asisthecase inthinpatients.Therearealsopatient-relatedfactorslikeage,genderand body habitus. In particular, young female patients and anxious or depressed patients experience more pain during ESWL. In routine clinical practice, there is a rather broad spectrum of protocols for pain treatment in ESWL. They may range between the extremes of general anaesthesia and simple oral medication.General anaesthesia for ESWL treatment is an option. General anaesthesia is safe and morbidity is low, with the obvious exception of high-risk patients. It is associated with a higher overall cost and a longer overall procedure time due to the need for post-operative recovery. It may entail practical problems, inparticularwithoutpatientprocedures.However,inyoungchildrenorin extremely anxious patients, general anaesthesia is the method of choice.Intravenousanalgosedationispossiblythemostwidelyusedprotocol forESWLtreatment.Itissuitableformostpatientsandoverallcostsare signifcantly lower than general anaesthesia. The administration of alfentanil withorwithoutpropofol,whichcanbeintermittentlyrepeatedwhen necessary, has a long history of effective use.6.2Pain management6Foradaptivedosageduringthetreatment,theuseofapatient-controlled medication pump is a well-proven option. ECG, blood pressure and oxygen monitoring are obligatory when administering opioids. Possible side effects are nausea, vomiting and respiratory depression.Effective pain management is mandatory for good treatment results.The need for pain treatment depends on shock wave energy level, skin-to-stone distance and patient-related factors.Intravenous analgosedation, which can be intermittently repeated when necessary, is the most common therapy to manage ESWL-induced pain.6.3Patient preparation Anynecessarymonitoringsensors,suchasECGelectrodes,shouldbe attached to the patient before stone targeting in order to avoid delays once the stone has been located and positioned in the shock wave focus. Likewise, the monitors which are required for the specifc protocol and patient-related risks should be started. RR blood pressure should be monitored, since increasing blood pressure (RR > 160/95 mm Hg) caused by pain, stress or insuffcient control of pre-existing hypertension may increase the risk of inducing kidney haematomas.The complete urinary tract needs to be examined immediately prior to ESWL in order to confrm the actual position of the stone and compare the fndings with pre-treatment diagnosis. The concretion may have changed its position, which may require an updated treatment strategy.Briefybutfullyexplainingthetreatmentproceduretothepatientcan signifcantly improve the patients relaxation and cooperation.Start the monitoring instruments (ECG, O2 saturation, RR).Urinary tract examination immediately before ESWL.Confrm the position of the stone.6How to perform ESWL?6 31326.4PositioningPatientmovementsduringshockwaveapplicationandrespirationcause the stone to move out of the shock wave focus and are detrimental to stone disintegration. Therefore, a stable patient position is essential for good disinte-grationresults.Sincethetreatmenttypicallytakesabout30to45minutes, thepatientrequiresacomfortableposition. Aneckroll,kneeroll,awedge orarmrestsareaccessoriesthathelptostabilizethepatientsposition.If possible, the supine patient position is preferred, since it is more comfortable for the patient and offers better access to the patient for the anaesthetist when doing general anaesthesia.Withalithotripterofferingbothunder-tableandover-tabletherapyhead positions, the patient can be treated in a supine position for all stone locations (See Fig. 6-1). Stones in the kidney and upper ureters down to the iliac crest are treated with the therapy head coupled in the dorsal or dorsolateral location. Since the iliac crest blocks the shock waves, stones in the distal ureter require a ventral or ventrolateral therapy head position. If the lithotripter only permits under-table therapy head positions, the patient needs to be positioned prone for ureteral stones distal to the iliac crest.Fig.6-1:DornierGeminilithotripter.Left:Set-upforstonetreatmentinleftkidney.The therapyhead(indicatedbyanarrow)iscoupledfromdorsolateral.Right:Setupforstone treatment in right lower ureter. The therapy head is coupled from the ventrolateral position.It is advisable to pre-position the patient in such a way that the stone is already in close proximity to the focus. This will avoid time-consuming moves later in the procedure.6.4Positioning6Abdominal compression by a belt reduces respiration-induced stone movements and thus increases the effcacy of the ESWL treatment. The belt should press on the abdomen and not on the thorax.A stable patient position is essential.Stones in the kidney and proximal ureter down to the iliac crest therapy head dorsal.Stones in the distal ureter therapy head ventral.Abdominal compression suppresses respiratory motion.6.5Stone targetingMost modern lithotripters offer both X-ray and B-mode ultrasound for stone visualization (See Fig. 6-2). Fig.6-2:Left:NativeX-rayimagewithradiopaquestonewithinthecrosshairs.The lithotripter coupling cushion of the therapy head is shading the right side. Right: Ultrasound image of a kidney stone. Within the crosshairs it is displayed by its bright stone refection. It is accompanied by an acoustic shadow behind the refection.Calciumoxalateandcalciumphosphatestonesareradiopaqueandhavea high density. Struvite, mixed and cystine stones have a lower density but are still visible on native X-ray images. Uric acid stones are radio-translucent and can only indirectly be visualized by X-ray using a contrast agent.6How to perform ESWL?6 3334Withultrasoundstonesarevisualizedbyabrightechomarkingthestone surfaceregardlessofthestoneschemicalcomposition.Thecharacteristic acousticshadowbehindthebrightstonerefectiondistinguishesastone from other bright structures such as blood vessels or a stent.Ultrasound is unsuitable for visualization of ureteral stones unless they are very proximal inadilatedsystemorpre-vesicalwherethebladderservesasanacoustic window. In the middle section of the ureter, ultrasound scanning cannot be used to locate stones, since anatomical landmarks are missing and intestinal gas and bone interfere (See Fig. 6-3).Fig.6-3:Ultrasoundimagingisappropriateforkidneystones,proximalanddistalureteral stones. 6.5.1 X-ray guided ESWLX-ray is the frst-line modality for imaging in ESWL, especially in the United States.Inordertotargetthestoneinthreedimensions,thestonehastobe alignedintwodifferentX-rayprojectionplanes.Ifthepatientisinsupine position, the stone is typically localized in the coronal plane by the vertical C-armposition(PAprojection).Thestoneisadjustedinthecraniocaudal (X-axis)andlaterolateralaxis(Y-axis).IntheangledC-armposition(CC projection), the stone is adjusted along the frontal axis (Z-axis). The targeting ofthestoneissupportedbysoftwarefunctionsspecifctothelithotripter model (e.g. image-oriented movement, auto-positioning).6.5Stone targeting6Initially, the full image area is used to confrm the position of the stone taking intoaccountvisiblelandmarkslikethespineandribs.Oncethestonehas beenidentifedandislocatedintheshockwavefocus,theimagedregion ofinteresthastobereducedinsizebyclosingtheX-raycollimator.This effectively reduces the patients radiation exposure.Since the target may get out of the shock wave focus due to patient movement or stone movement within the patient, stone positioning must be reconfrmed at regular intervals. If there is an apparent patient movement, stone targeting mustbecheckedimmediatelyafterthepatienthasreturnedtoastable position.Otherwiseimagingmayberepeated,forexample:every300-500 shockwaves.Eventhoughstonemovementsaremorelikelywithinthe coronal plane, imaging should not rely solely on the vertical C-arm position. Especially in the beginning of the treatment and if the position was corrected in the coronal plane, the ventrodorsal axis should be checked with the angled C-arm position.During ESWL treatment, the degree of stone disintegration may be assessed bydirectsigns(cracksinthestone,visualisationofmultiplefragments)or indirect signs (loss of density, softening of the margins).Target the stone in both image projection planes (PA and CC).Stone targeting must be reconfrmed at regular intervals.Reduce the image size for monitoring (reduction of radiation exposure).6.5.2 Ultrasound guided ESWLEventhoughmosturologistsroutinelyuseultrasoundimagingfor examinations of the urinary tract and for stone diagnosis, ultrasound guided ESWLisconsideredmorediffcult. Thismaybeexplainedbythefactthat thetransduceristypicallylocatedeitherwithinthebulkytherapyheador fxed in a holder. Thus, the scanning of the patient is quite different from the normal procedure in ultrasound examinations where the ultrasound scanner can be moved freely over the target organ. Instead of making small manual angular movements, the operator now has to move the patient by means of table movements. 6How to perform ESWL?6 3536Therefore,itcansometimesprovemorediffculttofndagoodacoustic window in rib gaps. Consequently, image quality is often inferior to standard freehandscanning.Withinlineultrasound,imagequalitymaysufferfrom additionalartefactscausedbythecouplingcushionandairbubblesinthe coupling interface.However, ultrasound guided ESWL is a procedure which can be learnt with sometrainingandisnotmoredemandingthanotherstandardprocedures performed by urologists. The use of ultrasound has some relevant advantages over X-ray guidance:There is no radiation exposure to the patient or personnel. Therefore, ultrasound can be used in continuous mode (real time) during the complete session.Real-time imaging allows better monitoring of the entire procedure: movements of the targeted stone or the patient are detected immediately.Smaller renal stones might be easier to detect.Uric acid stones can be visualized without the use of a contrast agent.During shock wave application a stone which is hit by shock waves seems to slightly jump, which is also sometimes described as pixel fickering. This may be used to monitor hits/misses.With inline ultrasound it is also possible to check the acoustic path of the shock waves, especially the coupling quality (See Fig. 6-4 and section 6.6).Giventheseadvantages,werecommendthatultrasoundbeusedwhenever possible.6.5Stone targeting6Fig. 6-4: Ultrasound monitoring of the contact zone with an inline transducer. Left: A bubble is revealed by its bright echo (white arrow) and posterior shadow (black arrows). Right: Image after removal of the bubble by wiping the cushion.Achievingpromptandreliablestonelocalizationbyultrasoundishighly dependent on the actual lithotripter being used. However, we like to stress that there are possible advantages to initial scanning with a freehand transducer. In this way it is possible to confrm that the stone planned for treatment can beadequatelyvisualizedbyultrasound. Alsothesuitableacousticwindow which could be used later by the outline or inline transducer may be selected. A pre-positioning of the patient such that only minor corrections are needed in the succeeding targeting is advisable.Use ultrasound imaging whenever possible.Pre-scanning with freehand ultrasound (-> selection of acoustic window for imaging, pre-positioning of the patient).Check for posterior stone shadow.6How to perform ESWL?6 37386.6CouplingWithmostmodernlithotripters,theshockwavesaretransmittedfromthe shock wave source to the patient via a water-flled cushion. To achieve a good transmission into the body, typically ultrasound gel is applied.Variousstudieshaveshownthatevenafewairbubblestrappedinthegel considerably reduce the effectiveness of the shock waves (See Fig. 6-5). In particular, incomplete coupling or a cushion which does not ft snugly against the body surface but has an air-flled wrinkle inevitably leads to ineffective treatment.Fig. 6-5: Reduction of disintegration capability by air trapped within the coupling zone. Results from in vitro model stone tests (for details see Bohris et al. 2012). Test results are the number of shock waves required for complete disintegration of the stone. Test was performed under various coupling conditions. When 20% of the coupling area was blocked by air bubbles, about three times the number of shock waves was needed as compared to the bubble-free condition.Sometipshelptoobtainabubble-freecouplingandavoidpoorcoupling conditions (See table). 6.6Coupling6Remove hair at the shock wave entry area.Store the gel bottle head down and do not shake it before use.Alargeopeninginsteadofasmalldiameternozzleshouldbe used when dispensing gel.Apply a suffcient amount (3050 ml) of low viscous ultrasound gel on the therapy head as a mound (See Fig. 6-6).Contact between the cushion and the patient should be achieved by infating the bellow or slowly lowering the patient onto the infatedbellow.Typicallythegelspreadsradiallywithoutair entrapment.Oncegoodcouplingisattained,thecontactbetweencushion and patient must not be lost during treatment. If contact is lost, the coupling procedure needs to be restarted.Coupling can be improved by manually wiping the cushion (See Fig. 6-6). Wiping is recommended after decoupling or frequent patient repositioning steps.Ifavailable,employinlineultrasoundorsurveillancevideoto monitor coupling.Fig. 6-6: Left: Applying gel to the cushion. Right: Improving coupling by manually wiping the cushion. During this procedure the infation pressure and patient position should be maintained so that the contact between bellows and skin is not lost.6How to perform ESWL?6 3940If the lithotripter therapy head is equipped with an inline ultrasound unit, the qualityofcouplingmaybemonitored(Fig.6-4)andimprovedasneeded. Even more convenient is the use of a surveillance camera which is integrated into the therapy head (See Fig. 6-7). Fig. 6-7: Video monitoring of the coupling area. Left: Numerous bubbles (dark) are located withinthegellayer(bright).Right:Areaafterremovalofthedisturbancesbywipingthe cushion.6.7Shock wave application treatment parametersTheaimofESWListodisintegrateastoneintofragmentsthatcanpass through the urinary tract system spontaneously. The disintegration improves as the shock wave energy dose, which is the total shock wave energy applied during one treatment, increases (See section 3.3). The energy dose must be suffcient to achieve adequate stone fragmentation and clearance so that the need for further procedures (re-ESWL, URS, PNL) is reduced. On the other hand,overtreatmentmustbeavoidedsincetheriskofsideeffectsisalso directly related to energy dose. 6.7.1 Kidney stonesWithinacertainrangetheaccumulatedshockwavedosemaybeapplied using different energy settings. If a lower energy is chosen, though, this must be compensated by applying a larger number of shock waves. It is generally recommendedtoadjustthetotaldoseandenergyleveltotheindividual patient (obesity, risk factors) and stone characteristics (stone size, chemical composition). Patient risk factors that require a lower shock wave dose are: 6.7Shock wave application treatment parameters6Untreated hypertensionDiabetes mellitusAge > 65 yearsImpaired renal function, hydronephrosisPaediatric patientsRenaltissuedamageandresultinghaematomacanbecausedbycavitation (Seesection3.4.4). Thetensilestressoftheshockwavemayinducesmall vapour bubbles in the blood. These bubbles are not stable but collapse after a sub-second lifetime. Both bubble expansion and collapse are accompanied by forceful stress to the proximity of the bubble which can damage the capillary walls.The risk of inducing cavitation within the renal parenchyma increases with theenergylevelused.Variousrecentpublicationshaveindicatedthatthe occurrence of cavitation is strongly related to the pulse repetition frequency. Loweringthepulserepetitionfrequency(PRF)isthusaneffectivewayto avoidrenalvasculardamage.Inaddition,aslowerPRFwillalsoimprove stonedisintegration,sinceablockingeffectbycavitationisavoided(See section 3.5).A pre-treatment (100-500 shock waves) at low energy levels is recommended to activate a protective effect in the kidney. Animal studies have shown that shock waves reduce the glomerular fltration rate and the renal plasma fow in the area exposed to the shock waves and even in the contralateral kidney due to induced vasoconstriction. If ESWL is performed with intravenous analgesia, it is a common practice in any event to increase the energy stepwise in order to adapt the patient to the shockwaves.OperatorswhoapplyESWLunderfullanaesthesiaandstart immediately with high-power shock wave levels should switch their strategy to a gradual energy increase in order to achieve better results.6How to perform ESWL?6 41426.7.2 Ureteral stonesIfthestoneislocatedintheureterinsteadofthekidney,thedoserequired forcompletestonedisintegrationisgenerallyhigher.Ontheotherhand,a somewhat higher energy level and shock wave frequency may be used if the kidney is not within the shock wave path. If the kidney is within the shock wave path, the same shock wave parameters as for kidney stones should be employed. This is of importance when treating upper ureteral stones.Adjust the shock wave parameters to the individual case.A low shock wave repetition frequency provides less renal vascular damage and better stone fragmentation. Use 60 shocks per minute.Activate vasoconstriction by a pre-treatment of low energy shocks combined with ramping up the energy slowly.When treating upper ureteral stones, check if the kidney is within the shock wave path. Adjust shock wave parameters accordingly.6.8Paediatric urolithiasisThissectionaddressessomeaspectsspecifctoESWLinthepaediatric population[11].Especiallyinthisgrouptheshockwaveenergydoseand radiation dose must be adapted to avoid the risk of long-term adverse effects, especiallyifpatientsneedtoundergorepeatedESWL.Alsothesmaller anatomy requires some adaptations in the procedure and settings.6.8.1 AnesthesiaWhereasESWLcanbeadministeredwithoutgeneralanaesthesiatomost adults, this is different with children. The need differs considerably depending ontheageofthechildandtheshockwaveenergyapplied.Olderchildren often tolerate ESWL under intravenous sedation, but with younger children general anaesthesia is the frst choice.6.8Paediatric urolithiasis66.8.2 Paediatric positioning aidThe table cut-out may be too wide for the treatment of infants. Some manu-facturers provide special positioning aids like an acoustically transparent sheet thatsupportsthebodyasshowninFig.6-8.Bubblefreeacousticcoupling must be provided between the coupling cushion and the sheet and between the sheet and the body.Fig. 6-8: Positioning aid which supports the body at a table cut-out.6.8.3 Lung protectionBecause the lungs in children are in closer proximity to the kidneys, special careneedstobetakentoprotectlungparenchymafromtheshockwaves, particularly when treating upper pole stones. The lung needs to be shielded with shock wave-absorbing materials, such as sheets of polystyrene or foam.6.8.4 ImagingImagequalityinchildrenisgenerallybetterduetothesmallerpenetration depth.Toavoidradiationexposure,ultrasoundisthepreferredimaging modality. It also permits continuous and close monitoring (real-time imaging).436How to perform ESWL?6446.8.5 Adapted shock wave parametersThenecessaryenergydoseasdefnedbyshockwaveenergyleveland number of shocks is generally lower in children than in adults. This may be attributedtothesmallerskin-to-stonedistanceandthegoodabilityofthe paediatric ureters to pass stones. However, an adequate dose must be selected by balancing safe stone clearance with avoiding auxilliary procedures which are related with potential additional risks. Paediatric positioning aid.Lung protection for children (e.g. polystyrene betweenthe chest and coupling bellow).Minimizing radiation exposure: preferably ultrasound localization.Adapt shock wave parameters.6.8Paediatric urolithiasis67Follow-upStone clearance is monitored in follow-up examinations. Success is verifed, orauxiliaryproceduresarespecifed.Eventhoughseverecomplications induced by ESWL are rare, subcapsular haematomas or septicaemia can lead tolife-threateningconditions.Suchcomplicationsmustbeidentifedand properly treated.7.1Stone clearanceAfter stone disintegration by ESWL, episodes of ureteral colic during passage offragmentsarecommon(8-10%).Renalcolicshouldbedealtwithlege artis. In case of (rapid onset) massive pain, an ultrasound exam is indicated to rule out renal haematoma (See section 7.3.1).In the treatment of kidney stones, colicky pain may be reduced and obstruction may be avoided by stenting. The insertion of a stent prior to ESWL is advised when the largest stone diameter exceeds 20 mm. However, routine stenting, especially in the case of ureteral stones, is not recommended [5].Pharmacologicalfacilitationoffragmentpassageormedicalexpulsion therapy (MET) can be accomplished by administering -receptor antagonists. Tamsulosinisthecommonlyusedcompound,butother-blockingagents appear to be similarly effective. MET is not recommended for the paediatric population due to the limited data for that group.Mechanicalpercussionandinversiontherapymayenhancepassageof fragments, especially originating from the lower pole calyces.Inmostcases,aplainX-ray(KUB)istakentodefnethestatusofstone clearance.Stone-freeratesaretypicallyhighinureteralstones,eventhoughrepeated ESWL treatment sessions are occasionally required.Inkidneystones,however,asubstantialnumberofpatientsshowresidual fragments.Whenthosefragmentsaresmallandarewithoutsymptoms, theyarereferredtoasclinicallyinsignifcantresidualfragments(CIRF)or asymptomaticresidualfragments(ARF).Thenumberofpatientswhoare stone-free typically increases with time. 45 746Therefore,mostclinicalreportsdonotreportstone-freeratesuntilafter 3 months. Final evacuation of CIRF or ARF from the lower pole calyx may takeupto24months.However,itmustbenotedthatthemanagementof patients with residuals after ESWL is an area that is still broadly debated. 7.2Stone analysis prevention of new stone formationMeasures to prevent new stone formation or to avoid growth of rest fragments are mainly dependent of stone composition.In order to provide the patients with advice regarding preventive measures to avoid new stone episodes, it is therefore advisable to obtain a stone analysis on the evacuated fragments if and whenever possible.The full extent of medical therapy of different stone types is a vast chapter and is beyond the scope of this booklet on the good practice of ESWL. We refer to the literature [12].7.3ComplicationsGenerallyandespeciallyincomparisonwithendoscopictechniques complication rate following ESWL is extremely low.Severe complications are extremely rare. Appropriate precautions need to be taken to avoid them.7.3.1 Subcapsular haematomaThe current EAU Guidelines [5] list the risk of symptomatic haematoma as less than 1% and the risk of asymptotic haematoma as 4%. Diagnosis is based onultrasoundorCTimaging.Clinicalsignsareabnormalpainfollowing SWtreatment,bulgingand/ortendernessofthefankregion,tachycardia, hypotensionorsignsofacuteanaemia.Themajorityofmanifested haematomascanbetreatedwithaconservativeapproach,includingblood transfusion in rare cases. Resorption may take 6 weeks to 6 months.Although the risk of an induced haematoma cannot completely be eliminated, it can be minimized when the ESWL is competently performed and patient-specifc risk factors are identifed and addressed. 7.2Stone analysis prevention of new stone formation7AdequateESWLtreatmentwasdescribedindetailinChapter6ofthis booklet.Inshort,bloodpressuremonitoring(Seesection6.3),precise shock wave targeting (See section 6.5) and careful selection of the treatment parameters (See section 6.7) are essential. In addition, it is recommended that ESWL treatments not be repeated within overly short intervals. There is no consensus as to the minimum interval, and this interval may also depend on theacousticdosesadministered.However,wesuggestwaitingatleasttwo weeks before performing a re-ESWL.Patient related risk-factors are:Treatmentwithanticoagulants(acetylsalicylicacid,coumarins, warfarin, etc.)Coagulation disordersHypertension or history of hypertensionDiabetes mellitusHigh age (> 65-70)Patientswhotakeanticoagulantslikeaspirin,warfarinorsimilaragents shouldnotbetreatedunlessthemedicationistemporarilydiscontinuedor substituted. For details, it is referred to Alsaikhan et al. (2011).ESWLshouldnotbeperformedonpatientswithcoagulationdisordersor hypertension unless they have been medicinally corrected.InallpatientswithriskfactorstheESWLtreatmentparametersshouldbe adapted to the specifc case.7.3.2 Septicaemia Inordertoanticipateeventualinfectiousproblemsitiswisetoperforma urine culture prior to ESWL in all patients, especially those with larger stones. AnyurinarytractinfectiondiagnosedpriortoESWLshouldbeadequately treated with antibiotics before scheduling the treatment. In the case of large, potentiallyinfectedstones,antibioticcoverageshouldcontinueduringand after ESWL.47 77Follow-up48Incasesofurosepsisthehighestprioritymustimmediatelybegivento removinganyobstructioncausedbyastoneorafragmentthatmightbe present. Further medical treatment of the septic problems cannot be successful until a possible obstruction has been removed.7.4Long-term complicationsAninitialstudybyKrambecketal.(2006)identifedahigherriskof developing hypertension or diabetes mellitus in patients treated by ESWL.Krambecketal.(2011)andChewetal.(2012)bothrefutedthesefndings with large cohort studies. They were unable to identify an association between ESWL and the long-life risk of developing hypertension or diabetes mellitus.It is now suggested that lithiasis per se and the metabolic disorders associated withitmayberesponsibleforchangesinbloodpressureandthehigher incidence of diabetes mellitus regardless of any stone treatment modality.8SummaryESWLisanexcellentfrst-linetreatmentforthemajorityofpatientswith urinarytractcalculi,providedthatthetechniqueisappropriatelyapplied. Therefore,operatorsmustbeproperlyeducatedandtrainedtoensure thesuccessofESWL.Thisbookletfocussesonthebasicprinciplesand practical aspects of ESWL and is intended to serve as an aid to any urologist performing ESWL. The literature section lists various review articles that are recommended for further reading.8Summary89Literature[1] C. Chaussy, W. Brendel et al. Extracorporeally induced destruction of kidney stones by shockwaves. Lancet 316: 1265-8, 1980.[2] G.G. Tailly.LithotripsySystems.In A.D.Smith,G.H.Badlaniet al.(Eds.)SmithstextbookofEndourology(3rdEdition). Wiley-Blackwell, 2012, pp 559-575. [3]A.M. Loske. Shock wave physics for urologists. Mexico: Universidad Nacional Autnoma de Mxico. ISBN: 978-970-32-4377-8.[4]R.O. Cleveland, J.A. McAteer. Physics of shock-wave lithotripsy. InA.D.Smith,G.H.Badlanietal.(Eds.)Smithstextbookof Endourology (3rd Edition). Wiley-Blackwell, 2012, pp 529-558.[5] C.Trk,T.Knolletal.GuidelinesonUrolithiasis.European Association of Urology, 2011.[6] G.M.Preminger,H.G.Tiseliusetal.EAU/AUANephrolithiasis GuidelinePanel.2007guidelineforthemanagementofureteral calculi. J Urol 178: 2418-34, 2007.[7] H.-G.Tiselius,C.G.Chaussy.Aspectsonhowextracorporeal shockwavelithotripsyshouldbecarriedoutinordertobe maximally effective. Urol Res 40: 433-46, 2012.[8] J.J.Rassweiler,H.-M.Fritscheetal.Extracorporealshockwave lithotripsyintheyear2012.InT.Knoll,M.S.Pearle.Clinical Management of Urolithiasis. Springer, 2013, pp 51-76.[9] C. Bach, N. Buchholz. Shock wave lithotripsy for renal and ureteric stones. Eur Urol Suppl. 10: 423-432, 2011.[10] M.J.Semins,B.R.Matlaga.Howtoimproveresultswithextra-corporeal shock wave lithotripsy. Ther Adv Urol 1: 99-105, 2009.[11] A.DAddessi,L.Bongiovannietal.Extracorporealshockwave lithotripsy in pediatrics. J Endourol 22: 1-22, 2008.[12] A. Hesse, H.G. Tiselius et al. Urinary stones. Diagnosis, treatment and prevention of recurrence. 3rd Edition. Karger, 2009.49 99LiteratureThis book, including all parts thereof, is legally protected by copyright. Any use, exploitation, orcommercializationoutsidethenarrowlimitssetbycopyrightlegislation,withoutthe publishers consent, is illegal and liable to prosecution. This applies in particular to photostat reproduction,copying,mimeographing,preparationofmicroflms,andelectronicdata processing and storage. Insofarasthisbookmentionsanydosageorapplication,readersmayrestassuredthatthe authors,editorsandpublishershavemadeeveryefforttoensurethatsuchreferencesarein accordance with the state of knowledge at the time of production of the book. Nevertheless,thisdoesnotinvolve,imply,orexpressanyguaranteeorresponsibilityon thepartofthepublishersinrespecttoanydosageinstructionsandformsofapplications statedinthebook.Everyuserisrequestedtoexaminecarefullythemanufacturersleafets accompanying each drug or system and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated bythemanufacturersdifferfromthestatementsmadeinthepresentbook.Everydosage schedule or every form of application used is entirely at the users own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. Someoftheproductnames,patents,andregistereddesignsreferredtointhisbookarein factregisteredtrademarksorproprietarynameseventhoughspecifcreferencetothisfact isnotalwaysmadeinthetext. Therefore,theappearanceofanamewithoutdesignationas proprietary is not to be construed as a representation by the publisher that it is in the public domain.HM1 at the Munich University Hospital GrohadernThefrstextracorporealshockwavelithotripsy(ESWL)treatment ofahumanwasperformedonFebruary07,1980byChristian Chaussy, Dieter Jocham, and Bernd Forssmann using a prototype DornierHM1(DornierHumanModel1).Theresultswiththis newtreatmentmodalityweresosuccessful,thatitthoroughly revolutionized modern stone management.The purpose of this brochure is to inform the user about the physical principles behind the technology and to offer practical guidance on performing ESWL.