Transurethral Resection of the Prostate presentation - wed MO teaching

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Issue 16 (2003) Article 8

ANAESTHESIA FOR TRANSURETHRAL RESECTION OF THEPROSTATE (TURP)

Mark Porter, Royal United Hospital, Bath, Bruce McCormick,Bristol Royal Infirmary, Bristol

INTRODUCTIONTURP is a cystoscopic procedure used to alleviate the symptoms

of bladder outflow obstruction, usually caused by benignprostatic hypertrophy (BPH). BPH affects 50% of males at 60years and 90% of 85-year-olds and so TURP is most commonlyperformed on elderly patients, a population group with a highincidence of cardiac, respiratory and renal disease. Themortality rate associated with TURP is 0.2-6%, with thecommonest cause of death being myocardial infarction. Safeanaesthesia depends on the detection and optimisation of co-existing diseases, and on weighing up the relative risks andbenefits of regional and general anaesthesia for each patient.


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TURP - IntroductionBPH affects

y 50% of males at 60 years

and

y 90% of 85-year-olds

y most commonly performed

on elderly patients, a

population group with a high

incidence of cardiac,

respiratory and renal

disease.


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TURP - Introduction

y The mortality rate associated with TURP is 0.2-6%,

with the commonest cause of death being

myocardial infarction.y Safe anaesthesia depends on the detection and

optimisation of co-existing diseases, and on

weighing up the relative risks and benefits of

regional and general anaesthesia for each patient.

y TURP carries unique complications because of the

need to use large volumes of irrigating fluid for the

endoscopic resection.


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TURP - surgical Procedure The operation is performed through

a modified cystoscope (resectoscope)

Prostatic tissue is resected using anelectrically energized wire loop.

Bleeding is controlled with a

coagulation current.

Continuous irrigation is necessary to

distend the bladder and to wash

away blood and dissected prostatic

tissue.


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TURP - irrigating solution Irrigation fluid must be non-conductive so that the

diathermy current is concentrated at the cutting point.

Irrigation fluid has to be non-haemolytic so thathaemolysis does not occur if it enters the circulation.

Irrigation fluid must have neutral visual density so that thesurgeons view is not distorted.

Most commonly used irrigants areglycine 1,5% in water ( 230 mOsm/L) or

Cytal a mixture of 2,7% sorbitol and 0,54% mannitol

(195 mOsm/L).


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TURP - irrigating solutionKeep in mind:

The most commonly used irrigants are

still hypotonic so that significant absorption of water

nevertheless can occur.

During a TURP - procedure 20 ml/min of irrigant solutionis normally absorbed. This is a total of 1 - 1.5 litres for the

average case.

Absorption up to 5 litres has been recorded.

In clinical practice it is almost impossible to accuratelyassess the volume absorbed.


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TURP - preoperative Considerations Patients for TURP are frequently elderley with coexistent diseases.

- cardiac disease 67%

- cardiovascular disease 50%

- abnormal electrocardiogram (ECG) 77%- chronic obstructive pulmonary disease 29%

- diabetes mellitus 8%

Occasionally patients are dehydrated and depleted of essentialelectrolytes (long-term diuretic therapy and restricted fluid intake).

Long standing urinary obstruction can lead to impaired renal functionand chronic urinary infection.

About 30% of TURP patients have infected urine preoperatively.


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PREOPERATIVE ASSESSMENTy Reduced functional reserve

y any organ failure

ymedical problems that can be improved before surgery,then TURP may need to be delayed.

y A decision can then be made with the patient between

regional and general anaesthesia, based on

consideration of the advantages and disadvantages ofeach technique in their particular case.

y risks of anaesthesia and surgery weight against the

potential benefits of an elective procedure such as TURP.


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PREOPERATIVE ASSESSMENT

History and examination

y Cardiovascular - Hypertension, ischaemic heart disease (IHD) andarrhythmias (particularly atrial fibrillation) are common. Patients with recentonset or poorly controlled heart failure have the highest perioperativemortality.

Major risk factors forIHD (hypertension, diabetes, smoking,hypercholesterolaemia and family history) will raise the likelihood of silentperioperative myocardial ischaemia.

y Respiratory - Marked decrease in functional ability (e.g. inability to climb oneflight of stairs) suggests severe disease. Inability to lie flat because ofdyspnoea from cardiac or respiratory causes will make awake spinalanaesthesia poorly tolerated.

y Neurological - Confused patients may be not lie still during spinalanaesthesia.

y Musculo-skeletal - Degenerative changes in the vertebral column may makesubarachnoid block (SAB) technically difficult.


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PREOPERATIVE ASSESSMENTHistory and examination

y Renal impairment may occur due to obstructive uropathy

y Airway - full anaesthetic assessment (e.g. anticipated airway difficulties) in case the regional

technique fails or is inadequate.

y Drug history - Beta-blockers suppress the compensatory tachycardic response to hypotension associated with

SAB or haemorrhage, but should generally be continued for prevention of perioperative myocardial

ischaemia.

- ACE- inhibitors limit the renin-angiotensin mediated response to hypovolaemia that may be

further impaired by SAB, and most anaesthetists omit them for 24 hours preoperatively.

- Alpha- blockers are commonly encountered as first-line medical treatment for BPH. The combined

hypotensive effects of these drugs may precipitate severe hypotension after SAB.

- Warfarin has implications for both the anaesthetist (regarding SAB) and the surgeon (intra- and

postoperative haemorrhage). If the INR is greater than 1.4 the procedure should be postponed until

the INR is acceptable.


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PREOPERATIVE ASSESSMENTInvestigations

Most patients are elderly and should have as routine:

y Full blood count or haemoglobin level

y Creatinine and electrolytes - this will detect renal impairment or overt renal

failure, commonly secondary to obstructive uropathy.y ECG for symptomatic patients, and routinely over 60 years

y Group and cross-matching blood for anaemic patients and those suspected

of having large prostates on examination or ultrasound scan.

other tests may be indicated in particular circumstances:

y Clotting studies (prothrombin time if on warfarin)

y Blood gas and pulmonary function tests (severe respiratory disease)

y Chest radiograph (worsening cardiac or chest disease / suspicion of

metastases)

y Urinalysis (for glucose, protein, blood, white blood cells)

y Blood glucose


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CHOICE OF ANAESTHETICy In the UK, 75% of TURPs are carried out under regional

anaesthesia.

y Although regional anaesthesia in an awake patient has

theoretical advantages, such as earlier detection of TURsyndrome (see below), the procedure can be equallysuccessfully accomplished using a general anaesthetictechnique.

y Short-term morbidity and mortality and long-term outcome are

similar irrespective of the technique used.y The decision is made after consideration of the individual's

medical status and detailed discussion of the relativeadvantages and disadvantages of each technique.


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CHOICE OF ANAESTHETICThe advantages of the regional technique include:

y Early detection of complications such as TUR

syndrome and bladder perforationy Possible reduced blood loss, requiring fewer

transfusions

yAvoids effects of general anaesthesia on pulmonarypathology

y Good early post-operative analgesia

y Reduced incidence of post-operative DVT/PE

y Lower cost


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CHOICE OF ANAESTHETICThe advantages of general anaesthesia are:

y Patients with chest disease may not tolerate lying flat orbe able to suppress their cough

y No time constraints. Although the procedure should bekept as short as possible - see later.

y May be less haemodynamically challenging than SAB inpatients with cardiac problems such as aortic stenosis

(and other fixed output states) andIHD

y Allows better control of CO2, which may reduce bleedingfrom the prostatic bed

y Patient preference.


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Anaesthetic TechniquePremedication

y Analgesics - give pre-emptive analgesia

(paracetamol +/NSAIDs if not contra-indicated)

y Anxiolytics - consider a short-acting benzodiazepine

if clinically indicated.

y In the elderly these drugs may result in postoperativeconfusion.


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TURP - preoperative Considerations Antibiotic prophylaxis (120 - 240 mg gentamicin) is

required for patients with a proven urinary tractinfection or a potential risk for infection ( indwelling

catheter or urinary obstruction).

antihypertensive and antianginal drugs should becontinued until the day of surgery to prevent reboundhypertension and tachycardia ( may result from

sudden withdrawal of these drugs - ACC/AHAguidelines).

antiobstructive drugs for pulmonary diseasetreatment should be continued.


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Anaesthetic TechniquePre-induction preparation:

- monitoring: blood pressure, pulse oximetry and ECG

for SAB,- including capnography, volatile agent levels, and

airway pressure for general anaesthesia.

- A reliable, large-bore intravenous cannulae (14-16G)should be placed.


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Anaesthetic Technique

Subarachnoid block / spinal anaesthesiay Check for any contra-indications to SAB

y A fluid preload with 500-1000ml of warmed saline 0.9% or Hartmann's iscommonly given

y Preloading assists compensation of the spinal-induced vasodilation andhypotension, and provides a small sodium load to counter thehyponatraemia that often occurs with TURP

y A confirmed block to at least T10 (level of the umbilicus) is required prior tothe start of surgery.

y

2.5 to 3ml of plain or heavy bupivacaine 0.5%y provides up to 3 hours of dense motor and sensory blockade.

y vasopressors (ephedrine 3- 6mg, or phenylephrine) should be immediatelyavailable. As a general guide, use ephedrine if the pulse is less than 60 perminute, and metaraminol if the pulse is over 60 per minute.


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Subarachnoid block / spinalanaesthesia

y Heavy lignocaine 5% 1.2-1.4ml can also be used,although the duration of block is unlikely to be reliableafter 90min. Adding adrenaline 0.2mg to hyperbariclignocaine will extend the block duration.

y Isobaric plain 2% lignocaine (with 0.2mg adrenaline toextend the block duration) in a dose of 2-2.5mL is also an

appropriate choice.y warming blanket and fluid warmer should be available for

prevention of hypothermia caused by the infusion of coldfluids and the effects of the irrigation fluid.

y All patients should be given supplementary oxygen.


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y regional anaesthesia does not abolish the obturatorreflex ( external rotation and adduction of the thighsecondary to stimulation of the obturator nerve byelectrocautery current through the lateral bladderwall). The reflex is reliably blocked only by muscleparalysis during general anaesthesia; another optionis an obturator nerve block using the nervestimulator.


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Consider intra-operative sedation for anxious or confused

patients (e.g. IV midazolam 0.5-1mg as needed), but bear inmind that confusion may also be an early manifestation of theTUR syndrome

Patients with chronic chest disease tend to cough on lying flat.Sedation can help to reduce coughing.

In elderly people 1 - 2 mg midazolam (+ fentanyl 50 mcg) isusually adequate.

Higher dose may result in loss of airway control, confusion andrestlessness.

A low - dose propofol infusion is an alternative (targetconcentration of 0.5 - 2.5 mcg/ml).


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General anaesthesiay in very obese or mentally handicapped (communication difficult)

patients

y spontaneously breathing technique using laryngeal mask,

y or a relaxant technique is appropriate, depending on the patient.y Elderly patients are very susceptible to the hypotensive effects of

induction and maintenance agents and have reduced requirementsfor volatile anaesthetic agents.

y Analgesic requirements can usually be met with pre-operativeparacetamol and NSAID and increments of an opioid such as

fentanyl, alfentanil or morphine. Further morphine in recovery isseldom required.

y Remember to consider the patient's renal function when using drugsthat are excreted renally (e.g. morphine and nondepolarisingneuromuscular blocking drugs other than atracurium).


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Other considerationsy Surgery is performed in lithotomy position - Keep in mind: Functional

residual capacity decreases, predisposing patients to atelectasis andhypoxia.

y Rapid lowering of the legs at the end of the operation acutely

decreases venous return and can result in severe hypotension,especially when combind with blood loss during surgery.

y Following the initial fluid infusion, i/v fluids should be given to replaceblood loss. Since irrigation fluid is continually absorbed during theprocedure, maintenance fluids are not required.

y Urologists often request antimicrobial prophylaxis to cover the gram-

negative bacteraemia. A single intravenous dose of gentamicin 3-4mg/kg is suitable.

y Where available, consider invasive blood pressure monitoring inpatients with severe cardiac disease.


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INTRA-OPERATIVE COMPLICATIONS

1) Hypotension

2) TURPsyndrome

3) Haemorrhage4) Bladderperforation

5) Hypothermia

6) Bacteraemia & sepsis

7) Positioning nervecompression

8) erection


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1) Hypotension

y The major complication related to anaesthesia is

hypotension following the sympathetic blockade ofSAB.

y inadvertently high blocks may cause resistant

hypotension and bradycardia is seen if the

cardioaccelerator fibres (from T1-4) are blocked.Treatment is with fluid, vasopressors and/or

inotropes as detailed above.


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2) TURP Syndromey occurs in up to 8% of cases in a mild form,

y severe in 1-2% of cases.

y Resection of prostatic tissue opens an extensive network of venoussinuses, which allows the irrigation fluid to be absorbed into thesystemic circulation. Features may develop peroperatively or in the

recovery room.

The volume of fluid absorbed depends on:

y the duration of the procedure (associated with large gland)

y the height of the irrigation fluid bag above the patient (increasedheight implies increased hydrostatic pressure driving the fluid

intravenously)y the vascularity of the diseased prostate

y An average of 10 to 30mL of fluid is absorbed per minute of resectiontime, amounting to up to 1800ml per hour.

y The glycine- containing irrigation solution is slightly hypo-osmotic(200mosm/l)


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2) TURP Syndrome

classical triad of features that make up TUR syndrome

are:

y

Dilutional hyponatraemia. Encephalopathy andseizures may develop when the sodium

concentration falls below 120mmol/l. Cerebral

oedema may occur.

y Fluid overload. This causes pulmonary oedema and

cardiac failure.

y Glycine toxicity. This inhibitory neurotransmitter

causes depression of the level of consciousness and

visual impairment at toxic levels.


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TURP syndrome - flow chart

TURP syndrom

Risk factors

1. Open prostatic sinuses

2. High irrigation pressure

3. Lengthy resection

4. Hypotonic irrigants

Irrigation

absorption

Solute

changes

Increasingvolume

Iv fluid

gain

hypervolemiaLeft ventricularfailure

Decrease

Increase

Blood

loss Diuretics

Solute loss

Hyponatremia Hyposmotility

Hypertension

Bradycardia

Increased

Capillaryleak

Glycine

Ammonia

Spinal

block

HypovolemiaHypotension

Pulmonary

oedema

Hemolysis

Cerebral

oedemaVisual changes

Seizureencephalopathy

Acute renal

failure

Respiratory

failure

CVScollapse

Death


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Symptoms and signs of TUR Syndrome:

y tachycardia

y nausea and vomiting - caused by hyponatraemia and cerebraloedema

y confusion / disorientation - hyponatraemia and cerebral oedema

y

hypertension (fluid overload), then hypotension (cardiacinsufficiency)

y transient blindness - glycine toxicity

y angina

y dyspnoea and hypoxia caused by pulmonary oedema

y cardiovascular collapse and arrhythmias (VT/VF)

y convulsionsy coma (Na


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2) TURP Syndrome

Factors which increase the risk of TUR syndrome

y pre-existing hyponatraemia or pulmonary oedema

y

prostate size larger than 60-100gy inexperienced or slow surgeon

y procedures longer than 1 hour

y hydrostatic pressure > 60cm H2O (height of bag

above patient)y reduced venous pressure (dehydration)

y use of large volumes of hypotonic intravenous fluids

such as 5% dextrose


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2) TURP Syndrome

Investigations

yA low serum sodium can confirm the diagnosis.

y

Levels below 120 mmol/L are invariably symptomaticand a rapid fall is more likely to produce symptoms.

y ECG manifestations of hyponatraemia such as QRS

widening, ST segment elevation and T wave

inversion usually only occur below 115mmol/l.y Hyperammonaemia is a common finding, being a by-

product of glycine metabolism.

yA low serum osmolality and high anion gap, caused

by the presence of glycine may be present.


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2) TURP Syndrome

Management

y airway, breathing and circulation (ABC) - Awakepatients may need to be sedated and ventilated,

whilst anaesthetised patients with mask airways mayneed intubation and positive pressure ventilation.

y Inform the surgeon and terminate surgery as soonas any bleeding points have been coagulated.

yInitial management of fluid overload andhyponatraemia involves stopping IV fluids andcommencing a fluid restriction (e.g. 800ml/24 hourscan achieve a rise in the sodium level of up to1.5mmol/l/24 hours). Give frusemide 40mg IV to

promote a diuresis.


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2) TURP SyndromeManagement

y Hyponatraemia causing encephalopathy requires more rapidcorrection than that achieved by fluid restriction and diuresisalone. Ideally these patients should be closely monitored onan intensive care unit. Hypertonic saline solutions (1.8%, 3%or 5%) should be used to increase the serum sodium level byabout 1 mmol/l/hour, not exceding an increase of 20mmol/l inthe first 48 hours of therapy. Sodium levels should be checkedevery few hours. Therapy with hypertonic saline should bestopped when symptoms cease or the sodium level reaches124-132mmol/l. Rapid correction has been implicated as a

cause of central pontine myelinolysis, which causesirreversible brain damage.

y Convulsions should be acutely treated with a benzodiazepine(e.g. diazepam 5-10mg) or small doses of thiopentone (25 -100mg). In the presence of intractable seizures, the sodiumlevel may be corrected more rapidly at a rate of up to 8-

10mmol/l/hour for the first 4 hours of therapy.


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3) Haemorrhagey Blood loss is very difficult to quantify.

y The amount lost is related the mass of gland excised,

y the duration of the procedure

y and the experience of the operator.

y In practice, clinical judgement based on duration of procedure,mass of prostate excised, the patient's vital signs and

communication with the surgeon are invaluable.

y If available, serial haematocrit levels are the most sensitiveindicators of the need for transfusion. Haemoglobin andelectrolytes should be measured the following day to exclude

sub- clinical anaemia and hyponatraemia.y Severe blood loss during TURP occurs in less than 1% of

cases. This may be the result of clotting abnormalities causedby the release of tissue plasminogen activator from theprostate and is possibly more common in malignant prostates.

Anti-fibrinolytics such as intravenous tranexamic acid and

aprotinin can be used to minimise active blood loss.


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4) Bladder Perforationy This complicates about 1% of cases of TURP.

y Most perforations are extraperitoneal and result insuprapubic, inguinal or periumbilical pain in the awakepatient.

y

The surgeon may notice reduced return of irrigation fluidfrom the bladder.

y Intraperitoneal perforation is far less common, but moreserious. In these cases the abdominal pain isgeneralised, and the patient may complain of shoulder-tippain. Pallor, sweating, peritonism, nausea and vomiting,

and associated hypotension may be present, dependingon the size of the perforation.

y Perforation may present as sudden, unexpectedhypotension under general anaesthesia. Managementconsists of immediate laparotomy and correction of the

defect.


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5) Hypothermiay The additive effects of general anaesthesia,

y the use of room- temperature IV fluids and large

volumes of irrigation fluids leave elderly patients

hypothermic.

yAll irrigation fluid should be warmed to body

temperature prior to use.

y Post-operative shivering can cause massively

increased myocardial oxygen requirements,reduction in cardiac output and a coagulopathy.


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6) Bacteraemia and sepsisy In as many as 6-7% of patients, a septicaemic

picture may develop.

y Septic shock following TURP is rare

y but has a mortality rate up to 75%.

yAntimicrobial prophylaxis with a single dose of

gentamicin 3 - 4mg/kg on induction is appropriate.

Cephalosporins may also be used.


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7) PositioningThe lithotomy position may cause

y nerve compression (especially involving the common

peroneal nerve from pressure effects exerted by the

stirrups),

y dislocation of hip prostheses,

y compartment syndrome in the lower legs and

respiratory compromise in patients with pre-existing

lung disease (reduction of functional residualcapacity.)


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POST-OPERATIVE COMPLICATIONSy Hypothermia

y hypotension,

y haemorrhage,

y septicaemia

y signs and symptoms of TUR syndrome

y acutely hypotensive after lowering their legs from the lithotomyposition because the reduction in venous return.

y Persisting hypotension that is unresponsive to fluid therapy, in theabsence of excessive blood loss, may indicate bladder perforation.

y Clot retention. Bladder clot may block the catheter causing painfuldistension of the bladder. If the clot cannot be dislodged withaggressive bladder washouts using the three-way tap on thecatheter, it may be necessary to insert a supra-pubic catheter.


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SUMMARYy TURP is a procedure carried out on a predominantly elderly

population with a higher incidence of coexisting disease.Consequently anaesthetising for the procedure may present achallenge to the anaesthetist, and carries a mortality risk of 0.2- 6%.

yA thorough preoperative assessment is important in detecting at-riskpatients, and helping to choose your anaesthetic technique. SAB iswidely considered the most suitable technique for TURP, althoughGA has a similar morbidity and mortality profile.

y Subarachnoid block to T10 provides excellent anaesthesia withoutnotable hypotension

y TUR syndrome is a rare but potentially fatal complication of TURP.Early recognition and prompt treatment are essential.

y Blood loss is difficult to quantify and may be significant. Closeattention to the patient's clinical state and communication with thesurgeon are vital.

Transurethral Resection of the Prostate presentation - wed MO teaching

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