ANAESTHETIC MANAGEMENT OF JOINT REPLACEMENT

SURGERIESDR. ARATI MOHAN BADGANDI

INTRODUCTION Joint replacement – common, effective procedure for relief of

disability due to severe joint pain and loss of function. most common joints replaced are the hip, knee and shoulder. Most patients for jt replacement have generalized degenerative

joint disease (eg.OA). Other conditions necessitating joint replacement surgery include:

› rheumatoid arthritis › osteoporosis and fracture › metastatic lesions and pathological fractures › avascular necrosis of the femoral head.

Most patients are elderly, with associated problems such as HTN, IHD, COPD or renal disease.

Younger pts presenting for jt replacement surgery often suffer from rheumatoid arthritis, severe osteoporosis or obesity.

Presentation for revision of previous replacement is increas ingly common.

Preoperative assessment

Problems in multiple systems are common because most patients are elderly.

There are specific types of pts who are more likely to have orthopedic surgery and are more likely to have perioperative complications.› geriatric pts› rheumatoid arthritis pts› ankylosing spondylitis pts

Geriatric Patients Postmenopausal, age-associated osteoporosis -

higher risk of fractures. Age-associated osteoporosis may be due to

increased circulating parathyroid hormone & decreased vitD, growth hormone.

With osteoporosis - disproportionate loss of trabecular (structural) bone – thus at risk for stress fractures.

Although all bones are at risk, thoracic and lumbar spine, proximal femur, proximal humerus, wrist are at highest risk.

Osteoarthritis

most common type of arthritis - loss of articular cartilage, inflammation.

Clinical manifestations - pain, crepitance, reduced mobility, and deformity of involved joints.

Hands – spurring, swelling of the distal IP jts (Heberden's nodes) and PIP jts (Bouchard's nodes).

no systemic manifestations of osteoarthritis - should be aware of previous orthopedic surgeries/ jt replacements / jts which are painful / limited mobility.

important for surgical positioning and the choice of an appropriate anesthetic.

Rheumatoid Arthritis chronic inflammatory form of arthritis, affects

about 1% of adults, prevalence 2-3 times higher in women than men.

characterized by persistent joint synovial tissue inflammation leading to bone erosion, destruction of cartilage, and loss of joint integrity.

RA also a systemic disease, affecting multiple organ systems.

often progresses through multiple exacerbations & remissions.

commonly present with pain and stiffness in multiple joints.

characterized by morning stiffness often lasting >1 hr after initiating activity.

usually wrists & MCP jts are involved (distinguishes RA from OA), boggy, tender & warm.

may have prominent epitrochlear, axillary, & cervical LN enlargement.

SC rheumatoid nodules may surround joints, extensor surfaces, and bony prominences.

pts taking NSAIDs should be assessed for GI SEs & renal complications.

Glucocorticoids - highly effective at relieving symptoms but used at low doses & sparingly ( due to SEs of osteoporosis, cataracts, cushingoid symptoms, hyperglycemia).

Pts taking glucocorticoids need stress-dose steroids for their operations.

Airway management can be challenging › TMJ synovitis limits mandibular motion & mouth opening. › Arthritic damage to cricoarytenoid joints - diminished

movement of VCs, narrowed glottic opening; preop as hoarseness and stridor.

› During DLscopy, VCs may appear erythematous /edematous, reduced glottic opening may interfere with passage of ETT.

› increased risk of cricoarytenoid dislocation with traumatic intubations.

› Arthritis of C-spine (atlantoaxial subluxation - Flexion of head - displacement of odontoid process into cervical spine and medulla - compression of vertebral arteries - precipitate quadriparesis, spinal shock, and death).

› Preop cervical flexion-extension radiographs required to plan for awake fiberoptic tracheal intubation, C-spine should be protected with collar.

Extra-articular manifestations of › Restrictive pericarditis

(dyspnea, RHF, fever, chest pain, pericardial friction rub, pulsus paradoxus).

› Pleural disease and intrapulmonary nodules.

› diffuse interstitial fibrosis with pneumonitis – PFTs restrictive ventilatory pattern - respiratory insufficiency, pulmonary HTN, RHF.

› Overlapping CTDs - Sjögren's syndrome, Felty's syndrome.

Airway Limited TMJ movement

  Narrow glottic opening

Cervical spine Atlantoaxial instability

Cardiac Pericarditis

  Cardiac tamponade

Eyes Sjögren's syndrome

Gastrointestinal

Gastric ulcers secondary to ASA, steroids

Pulmonary Diffuse interstitial fibrosis

Renal Renal insufficiency secondary to NSAIDs

Ankylosing Spondylitis chronic inflammatory arthritic disease that

results in fusion of the axial skeleton. ossification of axial ligaments progressing from

sacral lumbar region cranially, resulting in a significant loss of spinal mobility

significant challenge to us with regard to airway - reduced movement of their C-spines & TMJs.

In most cases, awake fiberoptic endotracheal intubation is required for GA.

increased rigidity of the thoracic spine in most cases also necessitates intraoperative controlled mechanical ventilation.

Although neuraxial anesthesia is better alternative to GA, ossification of spinal ligaments closes intervertebral spaces, blocking access to epidural space.

Extraskeletal manifestations 1. aortic insufficiency2. cardiac conduction abnormalities3. Iritis4. upper lobe fibrobullous disease ,pleural

effusions.

Strict attention to positioning to avoid fracture of the fused spine with concomitant spinal cord trauma.

Assessment of co-morbidities

Cardiopulmonary reserve estimated by assessment of exercise tolerance. may be impossible/ inaccurate (limited exercise).

In these circumstances the following may be used: PFTs, ABG, RA SPO2 resting ECG (silent ischaemia / previous MI) 2DEcho (LV function, WMA and valvular abnormality) limited relevance - information only about function of

rested, rather than stressed, cardiopulmonary systems. Dobutamine stress tests provide information about cardiac

function under stress but they are not readily available.

Renal function may be impaired owing to age, HTN or chronic

use of NSAIDs.

Musculoskeletal other joint involvement is common. range of limb and neck movements should be

noted. Obesity may be a cause or consequence of

degenerative joint disease. Assessment for positioning on table and for

regional blockade should be made.

Pts Excluded for Single Operation for Bilateral Total Knee Arthroplasty

Age ≥ 75 yr

ASA class III

Active ischemic heart disease (positive stress test)

Poor ventricular function (LVEF < 40%)

Oxygen-dependent pulmonary disease

Patients considered at increased risk for morbidity and mortality

 IDDM

 Renal insufficiency

 Pulmonary hypertension

 Steroid-dependent asthma

 Morbid obesity (BMI > 40)

 Chronic liver disease

 Cerebrovascular disease

Preoperative preparation

Preop assessment should be carried out as above. Optimization of co-morbidities is required. Cross-matched blood must be available. DVT prophylaxis is required. If a regional technique is

planned, ensure appropriate timing of low-molecular-weight heparin.

Antibiotic prophylaxis (usually cephalosporin or aminoglycoside) is required.

Invasive monitoring is seldom indicated unless there is sig nificant cardiac disease or large blood loss is anticipated.

Large bore IV access is required (non-dependent arm for laterally positioned patients).

Thromboprophylaxis in Orthopedic Surgery

1 of leading causes of morbidity after ortho surgery.

THR, TKR, hip and pelvic fracture surgery - highest incidence of VTE, including DVT and PE.

Pts with symptomatic PE have 18-fold higher risk of death than pts with DVT alone.

short-term complications of survivors of acute DVT and PE - prolonged hospitalization, bleeding complications related to DVT and PE treatments, local extension of DVT, and further embolization.

Long-term complications include post-thrombotic syndrome, pulmonary hypertension, and recurrent DVT.

As venous thrombi consist of fibrin polymers, anticoagulants administered for the prevention and treatment of DVT.

Thrombolytics should be administered only in event of a severe, possibly fatal PE.

LMWH is recommended over unfractionated heparin (IV/SC) for initial therapy of DVT and PE.

LMWHs do not require monitoring of coagulation. Although DVT prophylaxis may be more efficient when

started preoperatively, the risk of surgical bleeding also increases.

LMWH should be continued for at least 10 days in routine orthopedic procedures & in patients not considered high risk.

Extended prophylaxis to 28 to 35 days would be supported in patients with evidence of a DVT or at higher risk for DVT.

Risk factors for development of PE after surgery 1. advanced age2. Obesity3. previous PE and DVT4. Cancer5. prolonged bed rest

Warfarin - long-term treatment of DVT, with a target INR of 2.5 maintained for the duration of therapy.

alternative to LMWH is fondaparinux, synthetic pentasaccharide (selective inhibitor of factor Xa), prolonged half-life of 18 hours.

When administered OD, fondaparinux produces predictable anticoagulant response.

use of periop anticoagulants has significant impact on use of RA, esp. neuraxial anesthesia (risk of an epidural hematoma).

ASRA - updated consensus conference recommendations with regard to the use of anticoagulants and RA.

risk of epidural hematoma is significantly increased with use of LMWH, so following recommendations have been made:

1. An interval of 12 hrs after administration of usual dose of LMWH and placement of a neuraxial block.

2. In patients receiving larger doses of LMWH (enoxaparin 1 mg/kg every 12 hrs), delay should be extended to 24 hours.

3. Epidural catheter removal at least 8-12 hrs after last LMWH administration, or 1 to 2 hrs before the next.

Intraoperative ManagementTHRAPPROACHES

anterior / lateral approach. anterior approach - advantage of exposure without

violation of the muscles, but restricts full access to the femur with the risk of lateral femoral cutaneous nerve injury.

lateral posterior approach - excellent exposure to the femur and the acetabulum with minimal muscle damage, but increases the risk of posterior dislocation.

Most surgeons prefer lateral posterior approach, placing the patient in lateral decubitus position, surgical side up, for operation.

POSITIONING anesthesiologist must be aware that this position may

compromise oxygenation, esp in obese and severely arthritic pts, owing to V/Q mismatch.

to prevent excessive pressure on the axillary artery and brachial plexus by the dependent shoulder, an anterior roll or pad must be placed beneath the upper thorax.

TECHNIQUE nerve supply to hip joint includes obturator, inferior

gluteal, and superior gluteal nerves - RA best achieved with SAB/ epidural anesthetic.

lumbar paravertebral block may be used for postop analgesia when postop anticoagulation requires removal of epidural catheter.

BLOOD LOSS can be significant. Several studies have shown controlled hypotensive

epidural anesthesia with MAP of 60 mm Hg can reduce intraop blood loss for primary THRs to approx 200 mL.

Elderly patients able to tolerate this degree of blood pressure reduction without cognitive, cardiac, or renal complications.

hypotensive anesthesia may improve the cement prosthesis to bone fixation by limiting bleeding in the femoral canal.

femoral prosthesis can be fixed to femoral canal through methyl methacrylate cement or bony ingrowth.

Cemented fixation of the femoral prosthesis has been complicated by “bone-cement implantation syndrome,” which may result in intraop hypotension, hypoxia, and cardiac arrest and FES postoperatively

Several mechanisms suggested – embolization to circulation of bone marrow debris during

pressurization of femoral canal toxic effects of circulating methyl methacrylate monomer release of cytokines during reaming of femoral canal

promoting microthrombus formation and pulmonary vasoconstriction.

hypotension should be treated with epinephrine. Risk factors for this complication include revision surgery,

a long-stem femoral prosthesis, THR for a pathologic fracture, preexisting pulmonary hypertension, and the quantity of cement used.

TKR

TECHNIQUE innervation of the knee includes tibial nerve, common

peroneal nerve, posterior branch of obturator nerve, & femoral nerve.

RA as SAB / CSE / combination of femoral & sciatic block can be provided for the surgery.

Single-injection femoral nerve blocks in combination with intravenous and epidural patient-controlled analgesia have been employed to manage postoperative pain and improve functional recovery.

When LMWH has been instituted for the prevention of DVT, patient-controlled epidural anesthesia cannot be continued postoperatively, and instead continuous femoral nerve catheters are used.

TOURNIQUET APPLICATION routinely inflated over thigh during TKA to reduce intraop

blood loss, provide a “bloodless” field for cement fixation of femoral and tibial components.

when deflated, blood loss usually continues for next 24 hours.

Tourniquets are usually inflated to a pressure 100 mm Hg above pt's SBP for 1 to 3 hours.

Nerve injury after extended tourniquet inflation (>120 minutes) has been attributed to combined effects of ischemia and mechanical trauma.

Peroneal nerve palsy, a recognized complication of TKR caused by combination of tourniquet ischemia and surgical traction.

When prolonged tourniquet inflations are required, deflating the tourniquet for 30 minutes of reperfusion may reduce neural ischemia.

cuff should be applied over limited padding. Appropriate selection of tourniquet cuff size and inflation

pressure important to reduce risk of NM injury. cuff should be large enough to comfortably circle the limb

to ensure circumferentially uniform pressure. point of overlap should be placed 180 degrees from the

neurovascular bundle because there is some area of decreased compression at the overlap point.

width of the inflated cuff should be >half the limb diameter.

Before tourniquet inflation, the limb should be elevated for approximately 1 minute and tightly wrapped with an elastic bandage distally to proximally.

duration of safe tourniquet inflation is unknown. Recommendations range from 30 min - 4 hours. 5 min of intermittent perfusion between 1- and 2-hour

inflations, followed by repeated exsanguination through elevation and compression, may allow more extended use.

Prolonged inflation / simultaneous release of 2 tourniquets - significant acidosis, particularly in patients with an underlying acidosis due to other causes eg.DM.

Even with RA, some pts complain of dull, aching pain or become restless.

During surgery, however, opioids and hypnotics are usually effective.

postulated that tourniquet pain is caused by the unblocking of unmyelinated C fibers during recession of a neuraxial block.

addition of narcotics to spinal or epidural anesthesia may reduce tourniquet pain.

After tourniquet release, MAP falls significantly, partly owing to release of metabolites from ischemic limb into circulation & decrease in PVR.

advantages of SBTKR include exposure to risks of one anesthetic, one postoperative course of pain, reduced rehabilitation and hospitalization, and an earlier return to baseline function.

SBTKA associated, however, with a higher incidence of serious perioperative complications, including myocardial infarction, fat embolization, and thromboembolic events.

Anaesthetic technique

General anaesthesia: if general anaesthesia is indicated, bleeding may be

reduced by modest hypotension in carefully selected patients, using volatile agents.

For hip arthroplasty, analgesia may be supplemented by the use of a 3-in-1 (femoral/obturator/lateral cutaneous of thigh) block.

Some anaesthetists favour a lumbar plexus block because this also blocks the sciatic nerve, which has a component supplying the hip.

For knee replacement, a 3-in-1 block combined with a sciatic nerve block can be effective.

Regional anaesthesia is technique of choice because it: reduce incidence of major periop complications with

certain surgical procedures, including DVT, PE, blood loss, respiratory complications.

superior pain relief. Peripheral nerve blocks employing long-acting anesthetics

or catheters may provide excellent intraop anesthesia and superior postop analgesia.

preemptive analgesia. manipulation of airway, & conscious patients can aid safest

& most comfortable positioning for surgery. suggested that epidural anesthesia reduces venous

pressure, & this is significant factor in determining surgical bleeding, decreased need for bank blood and associated transfusion risks.

Sedation often desirable due to duration of operation, intraop noise.

Oxygen should be administered throughout the operative period.

As sedation deepens, airway obstruction or snoring may occur (not a problem in the lateral position, but some supine patients may require a nasopharyngeal airway).

Intraoperative problems

Patient position: in the lateral position, there is a risk of excessive

lateral neck flexion and pressure on the dependent limbs.

Hypothermia: orthopaedic theatres colder than other theatres, with

a higher velocity airflow leading to more rapid patient cooling.

Hypothermia causes poor wound healing, infection, coagulopathy and CVS dysfunction.

Fluid warmers, blankets and patient hats should be used routinely.

Blood loss: average blood loss in THR ranges from 300-1500 ml and

may double in the first 24 hours postop. During TKR with an intraoperative tourniquet, most blood

loss occurs in the recovery area. Careful fluid balance is essential because compensation for

hypovolaemia is poor in the elderly.

Cement reactions: At the time of cementing, a drop in blood pressure and

oxygen saturation is often seen. originally thought to be caused by a directly toxic effect of

the methyl methacrylate monomer component of the cement, but now known to be caused by a shower of microemboli of blood, fat or platelets forced into circulation by high intramedullary pressure during cement packing and prosthesis insertion.

Subsequent embolisation to the lungs produces a raised pulmonary vascular resistance and reduction in left ventricular return, resulting in hypotension.

microemboli are toxic to the lung parenchyma, causing haemorrhage, alveolar collapse and hypoxia.

may be severe enough to cause cardiovascular collapse, cardiac arrest and death.

Reactions are more common and more severe in bilateral joint replacements

therefore vital to ensure that the patient is not hypovolaemic before cementing.

Fat Embolism Syndrome well-known complication of instrumentation of medullary

canal. physiologic response to fat within systemic circulation. clinical manifestations of FES include respiratory,

neurologic, hematologic, and cutaneous signs and symptoms.

presentation of FES can be gradual, developing over 12 to 72 hours, or fulminant leading to ARDS and cardiac arrest.

Gurd and Wilson in 1974 suggested major and minor criteria to be used for the diagnosis of FES.

presence of any 1 major + 4 minor criteria and evidence of fat macroglobulinemia was required for diagnosis of FES.

More recent investigations have indicated that quantity of fat in circulation does not correlate with the severity of FES or development of ARDS

Gurd's Diagnosis of Fat Embolism Syndrome

Major Features (at least one)    Respiratory insufficiency   Cerebral involvement   Petechial rashMinor Features (at least 4)    Pyrexia   Tachycardia   Retinal changes   Jaundice   Renal changesLaboratory Features    Fat microglobulinemia (required)   Anemia   Thrombocytopenia   High erythrocyte sedimentation rate

Schonfeld Fat Embolism Syndrome Index Sign Score Petechial rash 5 Diffuse alveolar infiltrates 4 Hypoxemia Pao2<70 mm Hg, Fio2 100%3Confusion 1 Fever >38°C (>100.4°F) 1 Heart rate >120 beats/min 1 Respiratory rate >30 1

Score >5 required for diagnosis of fat embolism syndrome

petechial rash is pathognomonic, usually present on conjunctiva, oral mucosa, and skin folds of the neck and axillae.

mild hypoxemia and radiologic evidence of bilateral alveolar infiltrates, <10% progress to ARDS.

Neurologic manifestations – drowsiness, confusion, obtundation and coma.

treatment of FES is supportive with early resuscitation and stabilization to minimize the stress response to hypoxemia, hypotension, and diminished end-organ perfusion.

Deep Venous Thrombosis and Pulmonary Embolus

VTE major cause of death after surgery or trauma to the lower extremities.

incidence of fatal PE highest in THR for hip fracture.

Effective thromboprophylaxis requires knowledge of clinical risk factors in individual patients, such as advanced age, prolonged immobility or bed rest, prior history of thromboembolism, cancer, preexisting hypercoagulable state, and major surgery.

Antithrombotic Prophylaxis

LMWH started 12 hr before surgery / 12-24 hr after sx, or 4-6 hr after sx at half usual dose & then increasing to usual high-risk dose following day

Fondaparinux (2.5 mg started 6-8 hr after surgery) Adjusted-dose warfarin started preop or the evening

after surgery (INR target, 2.5; INR range, 2.0 to 3.0) Intermittent pneumatic compression is an alternative

option to anticoagulant prophylaxis in patients undergoing total knee (but not hip) replacement

Neueraxial Anesthesia and Analgesia in the Orthopaedic Patient Receiving Antithrombotic Therapy

LMWH placement should occur 10-12 hr after a dose. Indwelling neuraxial catheters are allowed with once, not

twice daily) dosing of LMWH. optimal to place/remove indwelling catheters in morning

and administer LMWH in evening to allow normalization of hemostasis to occur prior to catheter manipulation

WARFARIN Adequate levels of vit K-dependent factors should be

present during catheter placement and removal. Pts chronically on warfarin should have normal INR prior to

performance of regional technique. Monitor PT INR daily. Remove catheter when INR <1.5.

FONDAPARINUX Neuraxial techniques not advised in pts who are

anticipated to receive fondarinux periop.

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS No significant risk of RA-related bleeding is associated with

aspirin-type drugs. pts receiving warfarin or LMWH, combined anticoagulant

and antiplatelet effects may increase risk of periop bleeding.

other medications affecting platelet function such as thienopyridine derivatives and glycoprotein IIb/IIIa platelet receptor inhibitors should be avoided.

Postoperative Complications

Cardiac Complications ACC/AHA guidelines recommend preop cardiac testing in

pts at increased risk on basis of clinical risk profile, functional capacity, and type of surgery.

orthopedic surgery - intermediate-risk Older pts have an increased risk of periop myocardial

morbidity and mortality after orthopedic surgerypossible reasons for this increased risk are as follows: multiple medical comorbid conditions limited functional capacity some ortho procedures initiate a systemic inflammatory

response syndrome, significant blood loss and fluid shifts postop pain is a major management problem after

orthopedic surgery

All of these factors - stress response - tachycardia, hypertension, increased oxygen demand, and myocardial ischemia.

In pts in whom percutaneous coronary intervention involved placement of stents - added risks of restenosis and thrombosis if antiplatelet therapy discontinued before surgery - increased periop bleeding if not discontinued.

In elderly pts, β-blockers should be continued periop with a target heart rate less than 80 beats/min.

decision to initiate postop physical therapy and rehabilitation, depends on whether there has been a diagnosis of a postoperative myocardial infarction.

Respiratory Complications  elderly patients - progressive decrease in arterial

oxygen tension, an increase in closing volumes, decrease of approx 10% in FEV1 with each decade of life.

Due to alterations in chest wall mechanics, exacerbated in arthritis.

hypoxia reflects respiratory changes caused by age or embolization of bone marrow debris to the lungs in these patients.

Neurologic Complications confusion or delirium 3rd most common complication seen

in elderly patients associated with an increased length of hospital stay, poor

functional recovery, progression to dementia, and increased mortality.

Postop delirium manifests as › attention and awareness deficits› including acute confusion› reduced ability to focus› change in cognition› irritability› anxiety› paranoia› hallucinations.

develops acutely, but generally has a fluctuating course over several days

major risk factors for postoperative delirium › advanced age› alcohol use› preoperative dementia or cognitive impairment› psychotropic medications› multiple medical comorbid conditions. › Perioperative events (hypoxemia, hypotension,

hypervolemia, abnormal electrolytes, infection, sleep deprivation, pain, and administration of BZDs and anticholinergic medications).

Aging alters pharmacokinetics and pharmacodynamics of most medications, including anesthetics and analgesics.

may have longer and more profound CNS effects on elderly patients.

Strategies used to reduce incidence of postoperative delirium –› include identifying risk factors› vulnerable and affected patients› preserving orientation› early mobilization› adequate pain control› maintenance of normal sleep cycles› avoidance of psychotropic medications

Postoperative management

Analgesia

Epidural analgesia excellent, particularly in reducing quadriceps muscle

spasm following TKRs. increased risk of urinary retention catheterisation may cause a bacteraemia, increasing the

risk of prosthesis infection.

Patient-controlled analgesia is the choice in many institu tions. Intramuscular opiates may also be considered.

Regular paracetamol, 1 g/6 hours, should be given orally or rectally.

NSAIDs used with caution, especially in elderly, owing to increased risk of renal impairment.

Midazolam infusions or baclofen are sometimes required to ease quadriceps muscle spasm.

Fluid balance: stringent fluid balance monitoring is mandatory because

blood loss may double in the first 24 hours. Nausea may reduce the patient’s oral intake.

Oxygen: perioperative ischaemia is common and generally silent. Oxygen should be given for the first 72 hours postoperatively.

Shoulder replacementMonitoring and intravenous access Std full patient monitoring is required Large-bore IV access is made on the non-operative side NIBP monitoring is instituted either on the non-operative

side with a non-return valve on IV line, or on the lower leg.Anaesthetic technique GA using an armoured tracheal tube and positive-pressure

ventilation. Access to the patient’s head intraoperatively is extremely

restricted. interscalene approach to brachial plexus blockade provides

excellent intraop & postop analgesia, improves operative conditions, decreased blood loss, good muscle relaxation.

commonly gives a unilateral phrenic nerve palsy, seldom causes alveolar hypoventilation, even in spontaneously ventilating patients.

Patient position placed in sitting position,

with bolster behind the shoulder blades to improve surgical access

Care should be taken to ensure that there is no excess strain on the lumbar spine

torso should be securely strapped

head ring head securely fastened as

considerable pull and movement at shoulder.

Access to airway difficult, tracheal tube must therefore be securely taped in place.

eyes should be taped and well padded.

Intraoperative problems Elderly patients often have poor CVS compensatory

mechanisms while under GA. At the start of the operation, while positioning patient, drop

in BP may accompany change from supine to sitting vasopressors may be required. at risk of air embolism from open veins at the operative

site.

Postoperative management extremely painful and, if pos sible, interscalene block

should be used supplemented with patient-controlled opiate analgesia. Regular paracetamol and NSAIDs (in those in whom they

are not contraindicated) should also be prescribed.

Revision arthroplasty As number of active elderly people increases, more

patients are returning for revision of earlier replacements. As well as problems of TKR/THR, revision arthroplasties

have added complications associated with prolonged surgery and high blood loss.

Preoperative preparation anticipated blood loss - depends on the type of previous

prosthesis and the number of components being revised. Pre-donation of autologous blood with acute nor

movolaemic haemodilution Platelets (often not immediately available) and clotting

factors may be required.

Monitoring and intravenous access Invasive blood pressure and CVP should be considered urinary catheter for hourly urine output measurements.

Anaesthetic technique GA with CSE for pain, or CSE alone Spinal anaesthesia is generally unsuitable for length of the

operation outlasts its effects.

Intraoperative problemsTemperature: difficult to prevent perioperative hypo thermia long hrs, considerable volumes of intravenous fluid are

transfused. Fluid warmers, hot air blowers, humidification systems and

patient hats

Blood loss Pre-donation of one unit of blood, using acute

normovolaemic haemodilution, useful if pt has an adequate starting haemo globin level.

Platelets and fresh frozen plasma are often required.

Transfusion of pre-donated blood should wait until surgical haemostasis is obtained.

Fluid balance should be guided by surgical blood loss, central venous pressure trends (where available), pulse, blood pressure and urine output, with the aim of maintaining normovolaemia.

haemoglobin con centration should be assessed from blood gases.

Postoperative management high dependency unit Oxygen should be prescribed for at least 72

hours Analgesia should be pro vided by epidural

infusion with regular enteral paracetamol. Close control of fluid balance is aided by the use

of cen tral venous pressure monitoring and hourly urine output measurement

Coagulopathies should be treated, but the threshold to transfuse red cells depends, in part, on the pres ence of co-morbid medical conditions, especially ischaemic heart disease.

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