Anesthesia for Cystoscopy, Lithotripsy, TURP – Flashcards
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When would a cystoscopy call for anesthesia personnel
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- young children - mental disorders - anticipated pain like dilation of stricture
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Diagnostic indications for cystoscopy
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hematuria, obstructive symptoms, incontinence, congenital anomalies, retrograde studies of upper GU tract, biopsy of suspicious lesion
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Therapeutic indications for cystoscopy
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treatment of urethral strictures (painful), instillation of chemo or other medications, tx of urethral or bladder stones or some bladder cancers
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Anesthetic options for cystoscopy
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- local (topical LA only) - MAC - Neuraxial block - GA
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What is the most frequent choice of anesthetic for patents having routine cysto
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local
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When would you use MAC in a cysto
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patients with anxiety who may need a little sedation
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When would you use neuraxial block during a cysto
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uncommon since usually outpatient and can give post-spinal headache.
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When would you use GA during a cysto
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age or mental status is unable to cooperate - can usually just do mask or LMA
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Purpose of extracorporeal shock wave lithotripsy (ESWL)
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to disintegrate stones in the kidney or upper ureter by using energy from shock waves
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Common elements of lithotripters
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1. The energy source to generate the shock wave---often a spark plug, but may also be electromagnetic or piezoelectric 2. system to focus the energy wave (e.g. reflecting mirrors) 3. ability to visualize the stone (e.g. ultrasound or fluoroscopy)
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Technical explanation of extracorporeal shock wave lithotripsy (ESWL)
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- an electrode produces a spark which generates a pressure "shock" wave that is focused on the kidney stone (spark plug) - wave travels without dissipation of energy because the acoustic impedance of water & human soft tissue is similar - when shock wave reaches kidney stone, the impedance changes abruptly, causing release of energy - Repeated shock waves fragment the stone with minimal (but some) mild injury to surrounding tissue
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Cardiovascular changes in 1st generation (immersion) lithotripter
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- increase central blood volume - increase central venous pressure - increase PA pressure
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Respiratory changes in 1st generation (immersion) lithotripter
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- increase pulmonary blood flow - decrease vital capacity - decrease FRC - decrease tidal volume - increase RR
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Kidney innervation (sympathetic, parasympathetic, sensory)
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- sympathetic fibers from T8-L1 - parasympathetic - vagus nerve - sensory - pain referred to somatic distribution of T10-L2
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Ureter innervation (sympathetic, parasympathetic, sensory)
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- Sympathetic fibers from T10 - L2 - Parasympathetic - from sacral spinal segments S2 - S4 - Sensory - pain referred to somatic distribution of T10-L2
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Anesthetic options for immersion lithotripter
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- GA - Epidural - Spinal (needs to be T8) - skinsoft tissue infiltration and/or intercostal blocks + IV sedation
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GETA and immersion lithotripter
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can control breathing but incidence of accidental extubation or circuit disconnection because patient moved and lowered into bath following induction and we are far away
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Why is epidural not commonly used in immersion lithotripter
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time needed to establish block and if shock wave encountered air in epidural space, energy could be dissipated in epidural space risking neurologic injury
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Why might you not use spinal for immersion lithotripter
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more common hypotension than GA or epidural due to sympathetic block
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Newer lithotripters versus immersion lithotripter
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- no water bath - more focus shock wave
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Anesthesia for newer lithotripters
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- IV sedation (including "Big MAC" e.g. propofol infusion, bolus of short-acting opioid) - GA - inhalation or I.V., often with LMA ** (aspiration risk) - Spinal/epidural technically possible & effective but may delay discharge
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Why do we need to be cautious with LMAs for new lithotripter surgeries
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ureteral kidney stones are extremely painful, and can cause "renal colic" with nausea & vomiting plus high dose opioids are used causing large gastric volume AND lithotomy position causes upward pressure/regurge of gastric content
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Absolute contraindications to lithotripsy? What needs extra precaution?
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- pregnancy - active coagulopathy Extra precaution for: - Pacemaker/AICD (abd) - Orthopedic prostheses (don't want in path of shock wave) - Abdominal aortic aneurysm - Obesity/morbid obesity (obstruction)
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Effects of shock waves
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- Skin & flank bruising at entry site - Hematuria - I.V. hydration maintains UO & prevent clots & helps with passage of stone fragments - Lung easily damaged by shock waves - Arrhythmias less common than earlier lithotripters (Grounding of lithotripter helps prevent arrhythmias EKG artifact)
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Other options for stone removal if lithotripsy not recommended
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- laser lithotripsy - percutaneous nephrolithotomy (perc: incision in back and direct removal of stone) - ureteral stone removal from below with instrument through scope
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How is laser lithotripsy performed? When do we opt for this over lithotripsy?
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pulsed dye laser beam transmitted through green dye (need eye protection) then cystoscope - stones that are low in ureter and not amenable to ESWL
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What is the best anesthesia for a laser lithotripsy?
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GA or spinal at T8-T10 level
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Symptoms of prostate enlargement
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difficulty with urination; having to strain; getting up frequently at night but only being able to pass little urine; uncomfortable urine retention.
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Indication for TURP
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benign prostatic hypertrophy (BPH)
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How does TURP work
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cutting/coagulating, metal loop, or laser
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Bladder sympathetic innervation
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T11 - L2 to bladder through R & L hypogastric nerves - carry sensations of pain, touch & pressure - Sympathetic fibers in urethra are mainly α adrenergic - α blocking drugs a non-surgical tx for prostate enlargement
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Bladder and urethra parasympathetic innervation
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- from sacral S2-S4 - main motor supply to bladder - fibers carry sensations of bladder fullness/stretch
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Surgical goal of TURP
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resect as much prostate tissue as possible while leaving the capsule which surrounds the prostate intact to avoid irrigation fluid entering the circulation
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Ideal TURP irrigation
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- isotonic - electrically inert (electrolytes would conduct electricity, dispersing high-frequency current) - nontoxic - good visibility - sterile - cheap
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Types of TURP irrigating solutions
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Distilled Water - HYPOTONIC→ Hemolysis Glycine - biotransformation to ammonia →visual & neurologic changes Mannitol Sorbitol Glucose ** Normal saline can be used with certain TURP techniques
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Main complication of irrigation during TURP
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- fluid overload - if of non-salt containing solution will result in hyponatremia causing neurologic symptoms
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Anesthetic options for TURP
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- usually T10 spinal - GA
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Why is spinal preferred for TURP
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(T10) - Good operating conditions for surgeon (relaxed tissues) - *Allows monitoring for neurologic complications from hyponatremia or toxicity from irrigation* - Allows detection of perforation - Vasodilation from spinal helps in case of volume overload - Decreased incidence DVT - Decreased blood loss - Avoids cardiac depression from inhalation anesthetics
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When is GA required for TURP surgery
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if spinal is contraindicated, or if patient has medical conditions which would make it hard for them to tolerate effects of positioning (e.g. orthopnea)
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TURP complications
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- Absorption of irrigating fluid (Vol overload, Hyponatremia, "TURP Syndrome" associated with hypo-osmolarity) - Glycine Toxicity - Ammonia Toxicity - Perforation - Transient Bacteremia - Hypothermia (room temp irrigation fluids) - Bleeding
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Factors that affect absorption of irrigating fluid
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Prostate contains large venous sinuses; absorption further affected by: - Height of irrigation fluid (hydrostatic pressure) - Duration of resection (Average of 10-30 mL fluid absorbed PER MINUTE; Common goal is to limit resection time to 1 hour)
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Volume overload is a balance between
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fluid in (irrigation) fluid out (bleeding) redistribution (pooling blood in legs with spinal)
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What can fluid overload cause
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- dyspnea (can be exacerbated if trendelenberg required) - CHF - orthopnea - oxygen desaturation
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Volume overload and hyponatremia symptoms by the number
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*rate of decrease important* Na+ < 120 mEq/L: CNS sx's such as irritability, apprehension, confusion, headache < 115 mEq/L Na+, EKG changes (QRS widens, ST elevation) < 110 mEq/L Na+ seizures likely <100 mEq/L Na+ - seizures, coma, hypotension, arrhythmias, decreased force of myocardial contraction
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What happens during glycine toxicity/ammonia toxicity
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- glycine can act like inhibitory neurotransmitter in CNS and high levels may cause transient blindness - glycine goes through oxidative biotransform. to ammonia which in high levels causes delayed awakening after TURP
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Cardiac/respiratory complications from TURP surgery
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- hypertension - bradycardia/ arrhythmias - CHF - Pulmonary edema - hypoxemia - MI - hypotension
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CNS complications from TURP surgery
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- agitation/confusion - seizures - coma - blindness
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Metabolic complications from TURP surgery
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- hyponatremia - elevated glycine level - hyperammonemia
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"other" complications from TURP surgery
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hypo-osmolality Hemolysis
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How to treat TURP syndrome
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- terminate resection - restrict fluids - loop diuretic (furosemide/lasix) - RARELY hypertonic saline (3% NaCl indicated)
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Why is hypertonic 3% saline rarely indicated for TURP syndrome
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Hypertonic saline and rapid correction of hyponatremia is associated with cerebral edema & central pontine myelinolysis
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What is central pontine myelinolysis? What are the symptoms?
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loss of myeline in pontine area (pons) - sx can be muscle weakness, poor reflex responses, slow speech, balance problems, swallowing difficulties, tremor *permanent*
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When will perforation occur during TURP
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- tip of cutting electrode or over-distention with fluid
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Symptoms associated with perforation during TURP
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- lack of return of irrigation fluid - Can be associated with obturator nerve reflex (leg adduction) - Most extra-peritoneal = pain over the pubic bone, around the belly-button or in the groin - If intra-peritoneal, pain higher up (e.g. shoulder via diaphragm) + other sx's
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Symptoms of intra-peritoneal perf from TURP
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restlessness anxiety pallor sweating rigid abdomen N/V hypotension
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How many mL/min lost during TURP
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2-5 mL/min of resection time but blood + irrigation difficult to measure
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% of TURPs that get transfused
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2.5%
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Abnormal bleeding from TURPs can be from
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fibrinolysis DIC
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If fibrinolysis suspected from TURPs via lab work and clinical picture, how should we treat
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aminocaproic acid
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Why would a patient get fibrinolysis during a TURP
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The prostate contains plasminogen activator, which converts plasminogen to plasmin which breaks up fibrin.
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Why would a patient get DIC during a TURP
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possibly from systemic exposure to resected prostate tissue, which has thromboplastin. Thromboplastin converts prothrombin to thrombin, a key step in forming clot.
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TURP variations
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- Bipolar electrode (uses NaCl as irrigant) - Laser TURP (vaporize/coagulate tissue to decrease blood loss) - transurethral microwave thermotherapy
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Benefits of Bipolar electrode TURP procedures
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- Current jumps from one pole to other, unlike monopolar, where is disperses to surrounding tissue. - results in lower incidence of extravasation, hyponatremia, TURP syndrome, overall complication rate, transfusion rate, with similar efficacy of procedure.
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TURP most suitable for high risk patients
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TUMT (transurethral microwave thermotherapy) - can be office-based procedure with local anesthetic
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Complications from trendelenberg
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positioning may reduce lung volumes, and increase pre-load to heart
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Complications from lithotomy
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Nerve injuries: common peroneal n. sciatic n. femoral n.
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Peroneal nerve injury from lithotomy causes
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foot drop; inability to dorsiflex toes; numb shin/top of foot; high-stepping walk.
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Sciatic nerve injury from lithotomy causes
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weak knee flexion, weak plantar flexion of foot; numbness back of thigh; part of lower leg; bottom of foot.
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Femoral nerve injury from lithotomy causes
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difficulty extending knee; feeling like knee going to "give out" or buckle; numbness/tingling in anteromedial thigh; medial leg & foot ; weak hip flexion
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non-surgical treatment for prostate enlargement
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alpha blocking drugs (since sympathetic fibers in urethra are mainly alpha adrenergic)
