ANAESTHETIC MANAGEMENT OF TOTAL KNEE REPLACEMENT IN PATIENT WITH � ATRIAL FIBRILLATION

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INTRODUCTION

• The commonest Joint replacement surgeries are the Knee, Hip and Shoulder.
• These cases pose certain challenges to the anaesthesiologist due to decrease in organ reserves associated with ageing, comorbidities, polypharmacy and decrease in the activity of daily living.
• However, joint replacement surgeries are also performed in younger patients having connective tissue disorders and avascular necrosis.

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Pre-anaesthesia care and Prehabilitaion

• All these patients have to be evaluated in the preanaesthesia clinic.

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• Considerations in preanaesthetic evaluation
• Problem related to age and co-morbidities.
• Problem specific to the disease process leading to joint replacement.
• Plan of Anaesthesia.

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General Issues

• Check out the BMI – ask for history of OSA, daytime somnolence.
• Assess airway.
• Look for history of tingling, numbness, document it (Diabetes, radiculopathy, chemotherapy)
• Routine investigations asked for – Complete blood count, coagulation profile, renal function tests, liver function tests if there is a requirement, thyroid profile, viral markers, blood group and cross matching.
• Coagulation profile
• Examine back and gait of the patient.
• Rule out any infection

Preoperative prehabilitation

• Preoperative prehabilitation have become the order of the day and has been found to decrease the morbidity and mortality after joint replacement surgeries
• It includes chest physiotherapy, nutrition, muscle strengthening excercises, hematinics and erythropoietin administration.
• Phychological orientation and optimization of patient need.
• It is crucial to assess the organ function mainly the cardiorespiratory and the renal function.

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• Preoperative Hemoglobin levels need to be optimized and Hb of 10 gms% would be and ideal preoperative target.
• Albumin level less than 2.0 gms% indicate poor preoperative nutrional status indicator and increased risk of morbidity in the postoperative period which includes poor wound healing.
• Normalize the glycemic levels and blood pressure
• Preoperative ECG and ECHO for cardiac evaluation and Doppler study to rule out existing DVT.
• Assessment of Airway is very important in patients with connective tissue disorders as many of them might have fused spine and may require endotracheal intubation.

CARDIOPULMONARY CONCERN IN TKR

• Cardiopulmonary reserve is difficult to assess as exercise tolerance is limited by knee disease.
• Resting ECG may show silent ischemia or previous MI.
• METS score
• Metabolic equivalent is gold standard to evaluate patient physical capacity.
• If METS > 4 then ECG is sufficient. In case of METS < 4 or poor mobility ask for stress echo
• ATRIAL FIBRILLATION or other arrythmias

ATRIAL FIBRILLATION- PERIOPERATIVE MANAGEMENT FOR TKR

• Atrial fibrillation is the commonest arrythmia.
• It is associated with increasing age and results in significant morbidity.
• The management of AF is not a single step method it requires consideration of several aspects including the recognition of precipitating factors, appropriate anticoagulation and choosing a suitable method to either restore sinus rhythm or achieve rate control.
• Surgical patients can present AF in variety of ways :-

a) Pre- existing AF

b) New onset AF

AF ECG picture

• A resting ECG will reveal AF by the
• Absence of P wave
• Narrow QRS complexes that occur in an irregularly irregular rhythm.

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• For patients with known AF, a TTE (Trans Thoracic ECHO) is useful to ascertain the ejection fraction, exclude valvular heart disease and to look for regional wall motion abnormality (RWMA)

• A 12 Lead ECG showing Narrow QRS complexes which are irregularly irregular and are not preceded by P waves.

PRE-EXISTING ATRIAL FIBRILLATION

• Patients with persistent or permanent AF should have their heart rate adequately controlled prior to an elective operation. It is achieved by beta blockade or centrally acting calcium channel antagonists (CCB).
• Medications such as verapamil and diltiazem are often omitted on the day of surgery owing to their associated hypotension and profound bradycardia under anaesthesia.
• Cessation of medication should be based on individual cases prior to surgery

RHYTHM CONTROL

• Rhythm control for acute Afib

Hemodynamic stability

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Stable Unstable

Pharmacological cardioversion Electrical Cardioversion

No need for sedation/fasting Quick onset, needs sedation

ANTICOAGULATION

• Scoring systems such as CHADS2, and the newer CHA2DS2-VASc, stratify patients based on the NICE guidelines, and the scores predict the patient’s annual risk of stroke.

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• Patients at low risk (CHADS2 score < 1) require no anticoagulation, while those at high risk (CHADS2 score of 2 or more) require warfarisation to a target INR of 2-3, or an equivalent level with new anticoagulants such as Dabigatran.

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• Anyone with a score > 1 should probably also be warfarinised if there are no contraindications.

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• Prior to surgery it is important to ensure that anticoagulation is managed appropriately.

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WARFARIN REVERSAL (based on INR)

• INTRA- OPERATIVE MANAGEMENT

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• AF with a normal ventricular rate is usually asymptomatic and does not cause any major anaesthetic problems.
• AF with a rapid ventricular response can cause significant cardiovascular complications, including hypotension, rate related myocardial ischaemia, heart failure and pulmonary oedema.
• The first step in managing these patients is to identify any precipitating causes and attempt to correct these.
• Treatment should be commenced when adverse signs develop, such as rate related ischaemia evidenced by ST segment changes on continuous ECG monitoring, or hypotension secondary to the tachycardia.

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• There are no clear guidelines as to which pharmacological agent is preferred

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POST- OPERATIVE MANAGEMENT

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• Patients should continue their usual rate control medication peri-operatively and timing of recommencement of anticoagulation should be discussed with the surgical team.
• A strategy for prevention of thromboembolism often includes low molecular weight Heparin (LMWH), which is maintained while warfarin is restarted and a therapeutic INR range is attained.

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MANAGEMENT OF NEW ONSET AFIB INTRAOPERATIVELY

• Quickest method for converting new onset AF back to sinus rhythm is by Direct DC cardioversion.
• It is normally reserved for patients who are hemodynamically unstable.
• Recommended dose for cardioversion of AF is 120-150 Joules biphasic.
• Anticoagulation should be started at the same time.hey maintainace of
• After successful cardioversion, there is a high chance that patient may revert back to AF. That is why anticoagulation should continue with anti-coagulation to an INR of 2-3 for at least 4 week after cardioversion.

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MANAGEMENT OF NEW ONSET AFIB POSTOPERATIVELY

• Patient who respond to medication require maintenance dosage to ensure sinus rhythm is maintained.
• Correction of precipitating factors.
• Maintenance of Anti-Coagulation.

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ATRIAL FIBRILLATION MANAGEMENT ALGORITHM

ANAESTHESIA STRATEGY

• Total Knee Replacent
• General Anaesthesia/ Spinal anaesthesia/ Combined spinal epidural anaesthesia/Lumbar and sacral plexus block.

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• Intraoperative Position-

:- TKR is done in supine position.

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• Pre-emptive analgesia

:-The pre-emptive analgesia suggested includes Paracetamol 1gm, and Pregabalin 75mg on the day prior to surgery.

POSITION OF KNEE IN TKR

INTRAOPERATIVE CONCERNS

• BLEEDING :- Use of blood conservative surgeries including use of

antifibrinolytics like tranexamic acid. Close monitoring of

blood loss and adequate replacement

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• HYPOTHERMIA :- It is very common due to operating room temperature

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• TORNIQUET :- Whenever torniquet is used, it is essential to record the

time. Advocated time for upper limb is 90 mins and for

lower limbs is 120 min. The recommended pressure

should be 100 mmHg more than the systolic pressure.

• DVT
• BCIS- BONE CEMENT IMPLANTATION SYNDROME

PATHOPHYSIOLOGY OF BCIS

• Shower of microemboli of blood, fat or platelets forced into the circulation by high intramedullary pressure during cement packing and prosthesis insertion

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• Microemboli are toxic Produces a raised pulmonary

to lung parenchyma,causing resistance and reduction in left

hemorrhage, alveolar collapse ventricular return

and hypoxia

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Cardiovascular collapse, Hypotension

Cardiac arrest

Treatment of BCIS

• Early and aggressive resuscitation is the cornerstone of treatment.
• Administer 100% oxygen
• Invasive hemodynamic monitoring
• In severe BCIS regular advanced cardiopulmonary life support algorithms should be followed.

POST-OPERATIVE CONCERNS

• PAIN :- It is the most important concern in patients with joint replacement surgeries. Use of multimodal pain relief using combination of NSAID, Pregabalin, regional anaesthesia, Opiods and Tramadol. With the recent trend of Opioid free analgesia use of iv Ketamine, lignocaine and dexmedetomidine is tried these days.
• Nausea and Vomiting
• DVT :- Intermittent pneumatic compression device for 96 hours in the postoperative period and early ambulation decrease the incidence of DVT.

Chemoprophylaxis include LMWH, anti-platelets and anticoaugulants.

• Electrolyte Imbalance :- Most common are Hyponatremia and Hypokalemia
• HYPOXIA :- It is due to basal atelectasis. Put patient on incentive

Spirometry and chest physiotherapy. It could be due to

pulmonary embolism as well.

• Blood loss and replacement :-
• POUR – Post operative Urine Retention
• PCOD - Post Operative cognitive dysfunction.

It is important to rule out hyponatremia, hypoxia, hypoglycemia

hypercarbia,hypotension and hyperammonaemia

SUMMARY / TKR

• Patients coming for joint arthroplasties pose certain challenges to the anaesthesiologists due to decrease in organ reserves associated with ageing, comorbidities, polypharmacy, etc.
• The most important prehabilitation measures includes chest physiotherapy, nutrition, muscle strengthening exercises, haematinics and erythropoietin administration.
• The commonest electrolyte imbalance noticed in the elderly patients include hyponatremia and Hypokalemia.
• Albumin levels less than 2.0 gms% indicate poor preoperative nutritional status and increased morbidity in the postoperative period including poor wound healing.
• Intermittent pneumatic compression device for 96 hours in the postoperative period and early ambulation are advocated to decrease the incidence of DVT .

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