EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY (ESWL)

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Extracorporeal Shockwave Lithotripsy (ESWL) is a non-invasive procedure used to treat kidney stones and gallstones. The term "extracorporeal" means "outside the body," while "lithotripsy" is derived from the Greek words "lithos" meaning stone and "tripsis" meaning crushing. Therefore, ESWL literally means crushing stones outside the body.

Here's how the procedure works:

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1. Imaging: Before the procedure begins, the patient will undergo imaging tests, such as an ultrasound or a CT scan, to locate the stones.

2. Shockwave Generation: Once the stones are located, a machine called a lithotripter generates shockwaves. The patient lies on a cushion through which the shockwaves are directed.

3. Shockwave Delivery: The shockwaves travel through the body, reaching the stones without damaging the surrounding tissues. These high-energy shockwaves break the stones into tiny pieces, roughly the size of grains of sand.

4. Stone Elimination: The small stone fragments are then naturally eliminated from the body through urine over the course of a few weeks.

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Absolute contraindications: Pregnancy, bleeding disorder, anticoagulation

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Relative contraindications: Large calcified aorta, renal artery aneurysm, untreated UTI, pacemaker/AICD, morbid obesity

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After the procedure, patients may experience blood in the urine or pain as the small stone fragments are passed. In some cases, multiple ESWL sessions may be required to effectively break down larger or stubborn stones.

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                                                                       Anesthetic Implications for ESWL

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Anesthesia type: General, TIVA, MAC

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Airway: LMA

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Preoperative:

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• You will need a lead apron due to the use of X-rays to localize stones

• During ESWL, repetitive high-energy shocks (sound waves) are used and focused on the stone

• Renal insufficiency may be present if there is an obstruction

• Patients with a history of cardiac arrhythmias and patients with a pacemaker or internal cardiac defibrillator (ICD) may be at risk for developing arrhythmias

• If the patient has a pacemaker, programmability should be established prior to treatment

• AICD/defibrillator may misinterpret shock waves as an arrhythmia and inappropriately deliver a shock

• Pacemakers may "sense" shock waves and inhibit or trigger activity.

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Intraoperative:

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• The surgeon may place a stent prior to pulverizing the stones

• Decreased tidal volumes and increased respiratory rates are better for treatment efficacy

• Minimizing patient movement and respiratory excursion increase efficiency of stone damage

• Position: Supine, one arm extended. Sometimes prone

• Duration: 30-60 minutes

• The shock wave can cause dysrhythmias (R on T phenomenon)

• Shock waves can potentially trigger ventricular arrhythmias when they coincide with the repolarization period of the cardiac cycle

• Pain and discomfort are caused due to impact through cutaneous tissue and viscera

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Postoperative:

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• Pain management

• PONV prophylaxis

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Complications:

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• Hematuria

• Dysrhythmias

• PONV

• Adjacent Tissue/Organ Injury

• Infection

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Sources:

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Longnecker, D. E., Brown, D. L., Newman, M. F., & Zapol, W. M. (2012). Anesthesiology, 2nd ed.

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Macksey, L. F. (2011). Surgical procedures and anesthetic implications: A handbook for nurse anesthesia practice. 

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Jaffe, R. A. (2020). Anesthesiologist's Manual of Surgical Procedures (6th ed.). 

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Singh-Radcliff, N. (2013). 5-Minute Anesthesia Consult.

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