Anaesthetic choices for lithotripsy

Dr Nida FatimaDepartment of Anaesthesia and Critical care, JN

Medical college and hospital AMU aligarh

Urolithiasis• Prevalence of stone disease -1% to 15%.• Varies- age, gender, race, and geographic

location.• stone formation - migrated -lower to the

upper urinary tract.• once limited to men is increasingly gender

blind.

UROLITHIASIS

Forced Diuresis

Alkalisation of urine

Tamsulosine with

hydration

Extra Corporeal

Shockwave Lithotripsy

Percutenous Nephro-lithopexy

Uretro-Reno scopic Lithotripsy

Cysto-litholapexy

Pyelo/Nephro/Cysto/

Urethro- lithotomy

NephrectomyIf non

functional kidney

Endoscopic removal

• Lithotripsy( Greek) meaning "stone crusher“.• Techniques:• Extracorporeal shock wave lithotripsy• Laser lithotripsy• Electro-hydraulic lithotripsy• Mechanical lithotripsy• Ultrasonic lithotripsy

What is lithotripsy?

• Introduction ESWL in 1980. • 85% of renal calculi - treated• Externally generated, harmlessly penetrated

shock waves, provide pressure (900-1000 bar) on a kidney stone to disintegrate it into smaller granules.

Why lithotripsy?

Extracorporeal shock wave lithotripsy (ESWL)

• Disintegration of urinary stones in the ureter and kidney.

• High-energy waves (20 kilovolts)- focused on ureter or kidney.

• Lithotripter uses “R-wave ECG”- trigger for shock wave - refractory period of the cardiac cycle.

When lithotripsy?

MANAGEMENT OF RENAL CALCULI by ESWL

< 2cm in diameter and/or surface area < 500 mm2

Treatment : ESWL mono-therapy

> 2cm in diameter and/or surface area > 500 mm2

Treatment : PCNL +/- ESWL Combination therapy

Lithotripter• Comprises of:• spark plug• Energy reflector• Energy concentrator• Fluoroscopy• ultrasound

Spark plug Energy vaporize water external shock wave water bath/cushions Release energy patient’s body

stone

generate

Focussed on

Passed to

hits

Crushed to pieces

- The sudden expansion of air bubbles created sets up a pressure wave (shock wave)

- Focused onto F2 focus

- Exponential reductionenergy of wave beyond F2.

EFFECTS OF RESPIRATION

• For shock waves -most effective- stone at F2 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 :• decreased tidal volumes ,increased respiratory

rates, high-frequency jet ventilation .

Physiological effects of lithotripsy• Mechanical stimulation of myocardium and

conduction system…arrhythmias.• Atrial premature contraction• Ventricular premature contraction• Atrial fibrillation• Supraventricular tachycardia• Ventricular tachycardia

When a patient is placed in a water bath: Problems

• Cardiac preload is augmented• Increase in CVP and PCWP• Compression -peripheral venous system.• ↑ SV and cardiac output of 30%.• Hydrostatic pressure on the chest:

↓ FRC by 30% and VC by 20%.• ↓tidal volume , ↑ work of breathing

Changes on Immersion during Lithotripsy

Cardiovascular

Increased Central blood volume

Increased Central venous pressure

Increased Pulmonary artery pressure

Respiratory

Increased Pulmonary blood flow

Decreased Vital capacity

Decreased Functional residual capacity

Decreased Tidal volume

Increased Respiratory rate

• Newer lithotripters no need of water bath.• universal table for fluoroscopy.• energy can be focused more precisely.• less painful.

Renal changes

• Diuresis, natriuresis, and kaliuresis.• ↓ADH and renal prostaglandins

Temperature changes: • This heat transfer is augmented -vasodilation

produced by general or epidural anesthesia. • Hypothermia and hyperthermia have been

reported.

• The pathogenesis -multifactorial. • - Both cutenous and visceral nociceptors

Visceral nociceptors –• periosteal,• pleural,• peritoneal, • musculoskeletal pain receptors

PAIN

Variables associated with pain

• the type of lithotriptor, • size of focal zone• shockwave peak pressure,• size and site of stone burden• area of shockwave entry at the skin, • location of the shockwave front

Special considerations!!!

• Women of childbearing age need to undergo- a pregnancy test.• Abdominal aortic aneurysms with calcium deposits• orthopedic prostheses - kept out of the path of shock

wave.• Lung tissue -susceptible to shock wave injury- Hemoptysis

and pulmonary contusion.• Styrofoam padding.

• No incisions• No surgery• No lengthy hospital stays • No lengthy recovery periods

Advantages of lithotripsy

• Some discomfort. • Medicine to prevent infection. • Passing sand-like particles in

urine

Disadvantages of lithotripsy

• Weight > 300 pounds (140 kg)• Pregnant (absolute NO)• Bleeding diathiasis (relative)• Non- functional kidneys• Pacemaker in-situ• Contraindicated to anaesthesia or x-rays.

Who should not have lithotripsy?

Laser Lithotripsy

• Ureteral stones low in ureter and not amenable to ESWL.

• laser beam of 504-nm.• organic green dye. • Laser beam -absorbed by the stones• pulsatile energy is released - disintegration of the

stones

pulsed dye laser

• The anaesthesia method for ESWL procedures

Depends upon:• The level of patient consciousness• The spontaneous breathing ability • Need for intensive monitoring• Anaesthesia recovery time.

Anaesthetic choices for lithotripsy

• Patient’s ASA class.• Model of lithotripter – high-energy lithotripters

may require deeper level of sedation• Availability of certified anaesthetist or nurse

anaesthetist.• Location of lithotripsy treatment

General anesthesia

Analgesia-sedation

Spinal anesthesia

Epidural anesthesia

Flank infiltration ± intercostal

blocks

Monitored anesthesia care

Conscious sedation

Anaesthetic choices for lithotripsy

Conscious Sedation

• An altered state of consciousness• Minimizes pain and discomfort - analgesics and

sedatives.• Patients able to speak and respond.• A brief period of amnesia may erase the patient’s

memory of the procedure.

• Benefits:

• Ease of administration• Minimal equipment.• Rapid recovery time.

• Drawbacks:

• Diaphragmatic excursion• Increase treatment time • Decrease effectiveness of the treatment.• Unpleasant memories

Monitored Anesthesia Care(MAC Anesthesia)

• Patient protects the airway• Requires active participation of anaesthesiologist. • Can induce loss of normal protective reflexes • Loss of consciousness• The level varies widely during a single case and

from case to case.

• Benefits:

• A deeper level of anaesthesia• Diaphragmatic excursion is reduced• Improving treatment times and effectiveness

• Drawbacks:

• Must be administered by qualified anesthesia personnel.

• Diaphragmatic excursion when anaesthesia is not deep enough

• This can increase treatment time and/or decrease the effectiveness of the treatment

General Anesthesia (GA)

• Drug-induced loss of consciousness• Cannot be aroused, even by painful stimulation.• Impaired respiratory and cardiovascular function• If PPV → Securing airway using:• Laryngeal Mask Airway• Endotracheal Intubation

Benefit

• Rapid onset• Control of patient movement. • Ventilation parameters –controlled.• Decrease stone movement with respiration,• Effective stone targeting and fragmentation.

Drawback

• Morbidity and potential mortality • Longer hospital stay,• Expensive• Prolonged recovery• Strict monitoring • Equipment and personel

GA preferable

- Children,- Extremely anxious individuals, - Anticipated lengthy treatment • bilateral ESWL, • concomitant renal and ureteral stones, • calculi composed of cystine, or brushite, COM.

MAC VS GA

• MAC• Rapid recovery• Bypasses PACU• Fastracking surgery

• G.A• Prolonged recovery• Shorter duration of

ESWL procedure• Less opioids required

Regional Anesthesia

• Easier to provide.• Controlled loss of sensation.• Better analgesia.• Methods for shock wave include:• Spinal Anesthesia• Epidural Anesthesia

Epidural anesthesia

• Early recovery , good analgesia.

• LOR with saline• Smallest amount of air if necessary-provides

an interface → dissipation of shock wave energy and local tissue injury.

Spinal anesthesia

• Rapid onset• Hypotension is higher.• The incidence of hypotension with general ,

epidural, and spinal anaesthesia was 13%, 18%, and 27%, respectively.

Regional anaesthesia

• Drawbacks

• Postdural puncture headache (42%)• Transient neurological symptom• Urinary retention• Pruritis • Hypotension

• Flank infiltration ± intercostal blocks.

• L.A infiltration of flank ± intercostal blocks + intravenous sedation →adequate anesthesia avoids hypotension.

• Analgesia -sedation

Intravenous analgesia-sedation in various combinations has been used successfully

Thanks!!!