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UrolithiasisᵹAlthough stone disease is one of the most common afflictions ofmodern society, it has been described since antiquity. WithWesternization of global culture, however, the site of stone formationhas migrated from the lower to the upper urinary tract and the diseaseonce limited to men is increasingly gender blind.ᵹWith the lifetime prevalence of stone disease estimated at 1% to15%, varying according to age, gender, race, and geographic location, itis one of the most common diagnosis a patient presents in a UrologyOPD other than stricture and prostatism.ᵹRevolutionary advances in the minimally invasive and noninvasivemanagement of stone disease over the past 2 decades have greatlyfacilitated the ease with which stones are removed. However, surgicaltreatments do little to alter the course of the disease.
HIPPOCRATIC OATH :“I Will not cut, even for the stone, but leave suchprocedures for the practitioners of the craft”
ESWLᵹEngineers of Dornier Labs, Germany observed that during highspeed flight, shock waves generated by collision with raindropscaused pitting on the metal surfaces of supersonic aircraft.ᵹDr. Christian Chaussey and colleagues at Munich, succeeded inusing this principle to treat kidney stones by developing a lithotripsymachine.ᵹIt was Feb, 7th 1980 that this machinewas first used successfully for the cause,and as always, improvements followedsuit.
All lithotripters share similar technologic principles in havingthree main components:(1) an energy source,(2) a system to focus the shock wave; and(3) fluoroscopy or ultrasound to visualize and localize thestone in focus.
Three different generator types (energy sources) for Shockwavelithotripsy can be distinguished:-Electro hydraulic:- First generation lithotriperShockwave is generated by anunderwater spark discharge,which is reflected by an ellipsoid.Consists of a water bath and ametal gantry chair.Posed anaesthetic challenges due toimmersion in water.Now nearly obsolete.The second and third-generation lithotripters have evolvedmainly in the direction of multipurpose use, eliminating thewater bath and producing a pain-free lithotripter.
ESWLElectromagnetic:- The shockwave is generated by an electromagneticcoil, which moves a membrane.-An acoustic lens system reflects and focuses the shockwave.-The resulting shock wave is constant.-The energy is focused to a smaller focal point with higher peakenergy.Piezoelectric:- Shockwave generated by mechanical deformation of apiezoelectric crystal.-The crystals are aligned along spherical dish, which allows the focusing.-It induces low pain and can be used without any analgosedation.- The disadvantage is the large diameter of the source and the limitedtotal energy in the focus.
Shock wave generatorWaves travel through waterBody-water interfaceSimilar impedenceNo energy dissipationEntry surface of stoneSudden change in impedenceRelease compressive energyExit surface of the stoneAnother impedence changeShock wave energy released as a blast.Repeat cycles cause the stone to disintegrate.
Classical description- Patient immersed up to the clavicles, and- An electrode placed at the base of the tub in an ellipse- The electric energy creates a spark across the gapcauses- Generation of a loud noise,intense heat, and explosivevaporization of water.- The sudden expansion of airbubbles created sets up apressure wave (shock wave)- Focused onto F2 focus- Exponential reduction inenergy of wave beyond F2.
Newer lithotripersᵹNewer devices generate shock waves within a “shock tube”coupled to the body surface with a water cushion.This eliminates the water bath and all problems associatedwith patient immersion in water.ᵹThey also have decreased power, causing less pain.ᵹBut by decreasing power, efficiency of stone fragmentation isreduced. Thus the prevalence of retreatment is higher.ᵹNewer lithotripters use multifunctional tables that allow otherprocedures, such as cystoscopy and stent placement, to beaccomplished without moving the patient off the table.
Effects of respiration:-For shock waves to be most effective, the stone should remain in theF2 focus during treatment.Because of movements during respiration..The stone is likely to move in and out of focus.To increase the efficacy of the treatment advised techniques are,- decreased tidal volumes with increased respiratory rates, and- high-frequency jet ventilationHowever, studies in sedated patients with intercostal blocks and localinfiltration anesthesia have documented that stone movement withspontaneous respiration is mainly restricted to the F2 focal zoneduring ESWL.
Pain:- The pathogenesis of pain is considered to be multifactorial.- Both cutenous and visceral nociceptors are involved.Visceral nociceptors may include periosteal, pleural, peritoneal, and/ormusculoskeletal pain receptorsᵹVariables associated with pain :the type of lithotriptor,size and site of stone burden,location of the shockwave front,size of focal zoneshockwave peak pressure,area of shockwave entry at the skin
Physiologic Changes During Immersion LithotripsyCardiovascular changes-Increase in central blood volume-Increase in central venous pressure (about 10-14 cm H2O) and-Increased pulmonary artery pressure.Weber and colleagues observed that increases in central venous pressureand pulmonary arterial pressure were directly correlated with the depthof immersion.A decrease in cardiac output and an increase in systemic vascularresistance during immersion lithotripsy under general anesthesia hasbeen documented, mainly due to the sitting position.
Respiratory changesFRC and vital capacity are reduced by 20% to 30%,Pulmonary blood flow has been shown to increase, andtight abdominal straps and the hydrostatic pressure of water on thethorax impart a characteristic shallow, rapid breathing pattern.Ventilation-perfusion mismatch and hypoxemia are more likely.Renal changesDiuresis, natriuresis, and kaliuresis.A decrease in antidiuretic hormone and renal prostaglandins occurs.ᵹThe temperature of the bath water can cause profound changes inthe patients temperature. This heat transfer is augmented further bythe vasodilation produced by general or epidural anesthesia.Hypothermia and hyperthermia have been reported.
Changes on Immersion during LithotripsyCardiovascularIncreased Central blood volumeIncreased Central venous pressureIncreased Pulmonary artery pressureRespiratoryIncreased Pulmonary blood flowDecreased Vital capacityDecreased Functional residual capacityDecreased Tidal volumeIncreased Respiratory rate
ᵹFor effective stone disintegration, shock waves should reach the stoneunimpeded. Nephrostomy dressings be removed and Epidural andnephrostomy catheters be taped clear of the blast path.ᵹAlthough shock waves pass through most tissues relativelyunimpeded, they do cause tissue injury- Skin bruising and- Flank ecchymoses are common at the entry site.- Painful hematoma in the flank muscles may occur.- Hematuria is almost always present and results from shock wave–induced endothelial injury to the kidney and ureter.ᵹAdequate hydration is necessary to prevent clot retention.
ᵹLung tissue is especially susceptible to injury by shock waves.Air trapped in alveoli presents the classic water (tissue)-air interface to theshock wave and causes dissipation of energy with alveolar rupture andhemoptysis.Styrofoam sheet or Styrofoam board be placed under the back in childrento shield the lung bases from shock waves during ESWL.ᵹMechanical stress on the conduction system exerted by the shock wavesmay lead to arrhythmia, although rarely now-a-days.ᵹBrachial plexus injuries have also occurred from improper positioning ofpatients in the lithotripter chair.
Anaesthetic ManagementAnesthetic regimens used successfully for lithotripsyincludeGeneral anesthesia,Epidural anesthesia,Spinal anesthesia,Flank infiltration with or without intercostalblocks, Analgesia-sedation, including patient-controlled analgesia.
ᵹGeneral Anesthesia:-Advantages:--Rapid onset-Control of patient movement.-Ventilation parameters can be controlled decreasestone movement with respiration, which translates into more effectivestone targeting and fragmentation.Disadvantage:-- Morbidity and potential mortality associated with GA- Longer hospital stay, so expensiveTherefore, GA may be preferred in- Children,- Extremely anxious individuals,- Anticipated lengthy treatment (bilateralESWL, concomitant renal and ureteral stones, or calculi composed ofcystine, or brushite).
ᵹNeuraxial blockage:-Epidural anesthesiaAdvantage: An awake patient can help with transfers, reducing thelikelihood of injury.Saline , or only the smallest amount of air necessary should beinjected, for LOR :-Air in the epidural space provides an interface and causesdissipation of shock wave energy and local tissue injury.Neurologic injury has never been seen.However, increased procedural difficulty and slow onset ofaction are the reasons against its use.
Spinal anesthesiaRapid onset, simplicity and routineness of use.Intrathecal sufentanil is a safer and an effective alternative tolidocaine, resulting in- early ambulation and discharge,- ability to void,most likely due to preservation of motor and sensory function.However, its use results in undesirable pruritis .The incidence of hypotension (the patient is in a sittingposition for treatment) is higher, however. In one series, the incidence ofhypotension with general, epidural, and spinal anesthesia was13%, 18%, and 27%. Further, recovery is prolonged due to residualsympathetic blockade.
Local anaesthesiaAdequate anesthesia when combined with intravenous sedation andavoids hypotension.When given 1-2 min before the procedure in the target area, itresults in better pain control with lesser supplementary analgesiarequirement, thus reducing side effects of the other drugs.Prilocaine has been used in the form of subcutaneousinfiltration during ESWL. In comparison to lidocaine, it has a- rapid onset of action,- equal efficacy, and duration of effect- with lesser toxic effects due to rapid metabolism.Patient Controlled Analgesia may be used as well. It is said that PCAprovides a better compliance of treatment to the urosurgeons.
The EMLA cream : Used as an occlusive dressingIt can penetrate to a depth of 4 mm after 60 mins of application.It reportedly reduces opioid requirement by 23% during ESWLperformed with newer lithotriptors.However, its own analgesic effect is inefficient.Recently, the use of dimethyl sulfoxide (DMSO) incombination with lidocaine has been reported to provide better paincontrol during ESWL as compared to EMLA cream, due to- local anesthetic effect along with- diuretic,- anti-inflammatory,- muscle relaxant, and- hydroxyl radical scavenger effects of DMSO.
ᵹMonitored Anaesthesia Care: -The anesthesiologist is in control of the patients vital signs and isavailable to administer anesthetics and provide other medical care asappropriate.ᵹThe fentanyl-propofol combination has been proven as an effectiveIV analgesic option.Adverse effects:- centrally mediated respiratory depression along withdecrease in oxygen saturation,- nausea, vomiting, drowsiness, and hypersensitivityreactions.Therefore, regular oxygen saturation measurement isnecessary, especially when this drug is used along with sedatives inESWL.
- Both remifentanil and sufentanil have been found to be of equalefficacy with regards to analgesia, and patients and surgeons satisfactionduring ESWL.Remifentanil has a short elimination half-life and a rapid analgesicaction.- Lesser respiratory depression, nausea, and vomiting.- It can be safely used in clinically significant hepatic or renal diseases.- During MAC, this drug can be used as intermittent bolus doses or as acontinuous IV infusion as total intravenous anesthesia (TIVA) or as acombination of the two.However, all techniques of MAC require active patient monitoring duringand after the procedure for the potential adverse effects of opioidusage, especially respiratory depression, postoperativenausea, vomiting, and dizziness.
The ideal analgesia, which offers pain-free treatment, minimalside effects, and adequate cost-effectiveness, remains to be established.Combination therapy (oral NSAID and occlusive dressing ofEMLA, DMSO with lidocaine) offers an effective alternative mode forachieving analgesia with minimal morbidity. This therapy avoids theneed for general anesthesia, injectable analgesics, and opioids alongwith their side effectsHowever, any titrated, and well controlledanaesthetic approach will always be better than A “Hit-and-Trial” analgesia by the Urosurgeons.
ᵹThomas Hillier in 1865 : first therapeuticpercutaneous nephrostomyᵹHillier: repeatedly aspirated the hydronephrotickidney of a young boy for symptom relief.ᵹGoodwin and colleagues 1955: published their landmark report ontherapeutic percutaneous nephrostomy.ᵹFernström and Johansson (1976): Percutaneous removal of renalcalculi.
TECHNIQUEAccess RemovalᵹAccess: Fluoroscopic or ultrasonic control required.ᵹGenerally through a lateral calyx, one of the lower polar calycesin most instances.ᵹApproach through the upper polar calyces is useful for access tothe pelvis and UPJ, but the risk of pleural injury is significantlyincreased.
An 18--gauge needle is placed through the flank into the kidneyA guide wire of .035 or .038 size is passed through the needle.The tract is enlarged by passing serial or telescopic Teflon ormetal dilators co-axially over the guide wire.Amplatz sheath is passed over the last dilator,The nephroscope is passed throughthe sheath to visualize the inside of thecollecting system.
Stone RemovalSmall stones can be removed intact with forceps or basket.For Larger ones, Lithotripsy is requiredStone removal continues until the patientis free of stone or until it is necessary tostop the procedure.Common reasons for this includeprogressive bleeding andextravasation of irrigating fluid.UltrasonicPneumaticElectro-hydraulic
ᵹ. If the patient is not free of stone at the termination of theprocedure, the nephroscope can safely be reinserted through thesame tract after 48 hours.ᵹAt the end of the procedure, a nephrostomy tube is placedthrough the tract into the collecting system, large enough tomaintain an adequate tract to permit blood and clots to drainreadily.
-: Anaesthesia Considerations:-ᵹPractically all varieties of anaesthesia techniques have beensuccessfully used ranging from General anaesthesia to localinfiltration with sedation.ᵹPatient position: Usually prone position. In anesthetizedpatients, it has advantages over the supine position with regard tolung volumes and oxygenation without adverse effects onmechanics, including obese and pediatric patients.ᵹGA offers an advantage that the respiratory movements of thepatient may be synchronized with the procedure, so easing outthe surgeons job.
-: Anaesthesia Considerations:-Regional Anesthesia: -- The first description of PCNL with regional anesthesia was reported in1988; The authors described 112 patients who underwent percutaneousrenal surgery with epidural anesthesia. Hemodynamic and respiratoryparameters were satisfactory in 88% of the cases.- In 1991, Saied and colleagues found that an interpleural block produceda totally pain-free operation and necessitated less frequentadministration in the postoperative period.- General anesthesia can be a challenging in some situations such asPCNL for staghorn calculi, because of the possibility of fluid absorptionand electrolyte imbalance. Therefore, regional anesthesia may be a goodalternative.
-: Anaesthesia Considerations:-- In 2005, Singh and coworkers reported tubeless PCNL underregional anesthesia. They considered that by omission of thepercutaneous nephrostomy tube and adopting regional (spinallow-dose anesthesia, low-dose bupivacaine plus fentanyl) in placeof general anesthesia in selected patients, one may further reducethe morbidity without compromising effectiveness and safety.- Salonia and colleagues found that epidural anesthesia allowedgood muscle relaxation and a successful surgical outcome in thesepatients. Moreover, it resulted in less intra-operative bloodloss, less postoperative pain, and a faster postoperative recoverythan general anesthesia.
Fluid management is important.ᵹDuring nephroscopy procedures, continuous irrigation of fluidthrough the endoscope is necessary to prevent blood and debrisfrom obscuring the surgeons vision.If a significant discrepancy exists between the amount ofirrigating fluid infused and output from the patient, thenclinical evaluation of the patient for extravasation of irrigationfluid into the retroperitoneal, intraperitoneal, intravascular, orpleural spaces is warranted.ᵹIntravenous absorption of irrigation fluid can create a situationsimilar to that seen with TUR syndrome, in which electrolyteabnormalities and fluid overload can occur.
ᵹCarried out as Ambulatory cases.ᵹBenefits of Ambulatory Surgery- Patient preference, especially children and the elderly- Lack of dependence on the availability of hospital beds- Greater flexibility in scheduling operations- Low morbidity and mortality- Lower incidence of infection- Lower incidence of respiratory complications- Higher volume of patients (greater efficiency)- Shorter surgical waiting lists- Lower overall procedural costs- Less preoperative testing and postoperative medication
Pre-Operative managementMinimize patient anxiety by using both pharmacologic (e.g., benzodiazepines)and nonpharmacologic (e.g., relaxation therapies) approaches.Patients should be encouraged to continue all their chronic medications up tothe time that they arrive at the surgery center. Oral medications can be takenwith a small amount of water up to 30 minutes before surgery.NPO guidelinesProlonged fasting does not guarantee an empty stomach at the time ofinduction.Due to short half-life of clear fluids in the stomach (10-20 minutes), residualgastric volume after 2 hours is less in patients ingesting small amounts of clearfluids than in fasted patients.Furthermore, the ingestion of 150 mL of either coffee or orange juice 2 to 3hours before induction of anesthesia had no significant effect on residualgastric volume or pH even in obese adults.Thus, arbitrary restrictions prohibiting outpatients from drinkingfluids on the day of surgery are completely unwarranted.
Basic Anesthetic TechniquesQuality, safety, efficiency, and the cost of drugs and equipment are allimportant considerations in choosing an anesthetic technique for ambulatorysurgery.The ideal outpatient anesthetic should:-‐ Have a rapid and smooth onset of action,‐Produce intraoperative amnesia and analgesia,‐provide optimal surgical conditions and adequate muscle relaxation with ashort recovery period and‐ no adverse effects in the postdischarge period.
General AnaesthesiaᵹThe ability to deliver a safe and cost-effective general anesthetic with minimalside effects and rapid recovery is critical in a busy outpatient surgery unit.ᵹDespite a higher incidence of side effects than local or regionalanesthesia, general anesthesia remains the most widely used anesthetictechnique for ambulatory surgery.ᵹTracheal intubation causes a more frequent incidence of postoperativeairway-related complaints, including sore throat, croup, and hoarseness than afacemask or laryngeal mask airway (LMA). Most outpatients undergoingsuperficial procedures under general anesthesia do not require trachealintubation unless they are at an increased risk for aspiration.ᵹWhen compared with a facemask and oral airway, patients with an LMA hadfewer desaturation episodes, fewer intraoperative airway manipulations, andfewer difficulties in maintaining a patent airway.
ᵹPreMedication :- A Combination of a short acting benzodiazepine with ananticholinergic is usually preferred. An additional agent for preemptiveanalgesia may be added as per doctors preference.ᵹFor induction, the available options are- Barbiturates- Benzodiazepines- Etomidate- Ketamine- Propofol- Inhaled agents.Propofol is the most favored agent. It has quick onset of induction, superiorand fast recovery, minimal post operative side effects, no PONV and noresidual effects.Inhaled agents are as good choices. Changes in the depth of anesthesia canbe achieved readily because of the rapid uptake and elimination of theseanesthetics. The rapid elimination of anesthetic vapors also provides for fastrecovery and potentially earlier discharge from the outpatient facility.
Contraindications to Outpatient Surgery1. Potentially life-threatening chronic illnesses (e.g., brittlediabetes, unstable angina, symptomatic asthma)2. Morbid obesity complicated by symptomatic cardiorespiratoryproblems (e.g., angina, asthma)3. Multiple chronic centrally active drug therapies (e.g., use ofmonoamine oxidase inhibitors) and/or active cocaine abuse4. Ex-premature infants less than 60 weeks’ postconceptual agerequiring general endotracheal anesthesia5. No responsible adult at home to care for the patient on theevening after surgery
ᵹMiller’s Anaesthesia, 7th editionᵹEndourology and stone disease.Results and Complications of Spinal Anesthesia inPercutaneousNephrolithotomy by Sadrollah Mehrabi, Kambiz Karimzadeh Shirazi..ᵹJournal of Endourology, Volume 23, Number 11, November 2009.Percutaneous Nephrolithotomy Under General Versus CombinedSpinal-Epidural AnesthesiaᵹClinical anaesthesia by Barash, Cullen and Stoelting.ᵹhttp://www.nysora.com/peripheral_nerve_blocks/nerve_stimulator_techniques/3095-obturator-nerve-block.htmlᵹhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684259/(Indian Journal Of Urology - Analgesia for pain control duringextracorporeal shock wave lithotripsy: Current status)