Preoperative Assessment

M K Alam MS; FRCS

ILO’s

• At the end of this presentation students will be able to: Understand the principles of preparing patients for

surgery. Describe the systemic approach in preoperative

assessment. Name common problems affecting patient’s fitness for

surgery. Describe the management of chronic medical

problems. Outline DVT prophylaxis measures. Describe how to take informed consent.

Introduction

• Careful preoperative assessment essential for good surgical outcome.

• Assessment modified for emergency surgery.• Benefit of operation vs no surgery vs no treatment.• Decision to operate- patient fitness for surgery

usually decided few weeks before surgery.• Identify comorbid conditions and optimize it.• Preoperative clinics before admission for surgery.

Priorities

• Establish extent & severity of condition requiring surgery.• General medical history.• Assessment for comorbid and undiagnosed diseases.• Medications.• Details of previous surgery and anaesthesia.• Anaesthetic review before admission.• Morning of surgery: Reassess with all investigation results.

ASA classification

• ASA Physical Status 1 - A normal healthy patient• ASA Physical Status 2 - A patient with mild systemic

disease• ASA Physical Status 3 - A patient with severe systemic

disease• ASA Physical Status 4 - A patient with severe systemic

disease that is a constant threat to life• ASA Physical Status 5 - A moribund patient who is not

expected to survive without the operation• ASA Physical Status 6 - A declared brain-dead patient

whose organs are being removed for donor purposes

Oxygen

• Postop. Morbidity/ mortality related to O2 delivery to tissues.

• Patients with poor cardiorespiratory reserve and anaemia at higher perioperative risk.

• Optimizing this- minimizes the risk

Systemic preoperative assessmentCVS

• Angina, myocardial ischemia, exertional dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, dependent oedema, arrhythmia, murmur, hypertension, antiplatelet drugs and anticoagulant are indication of cvs disease.

• Cardiology consultation. • Optimization before surgery.

Respiratory system

• New cough, sputum or wheeze- new or exacerbation of pre-

existing respiratory disease.

• Asthmatics or COPD with purulent sputum- infective exacerbation.

• Respiratory viral illness- postpone surgery if possible.

• Smoking- advise to quit.

• Functional reserve: How many stairs can climb before needing rest?• ABG, respiratory function test.

• Pulmonologist consultation

Nutritional status• Weight (<90% predicted), BMI• History of weight loss- • Malnutrition: Low BMI- less than predicted > 20% weight loss Hypoproteinaemia Hypoalbuminaemia

• Delay surgery to treat malnutrition if possible• Obesity: Increased risk from surgery & anaesthesia.

Advise: Loose weight (dietician referral, supervised exercise)

Medications

• Long term steroids: needs higher dose during perioperative period. 100mg Hydrocortisone every 6 hours. Gradually reduced in postoperative period.

• Antiplatelet drugs: Aspirin, clopidogrel should be withdrawn only after cardiology consultation.

• Warfarin: Stopped 4-5 days before surgery, started on IV unfractionated heparin or subcutaneous low molecular weight heparin. Warfarin restarted after risk of bleeding is over. Heparin stopped once INR is in therapeutic range (2.5-3)

• Psychiatric medications can complicate anaesthesia. Anaesthetist informed. MAOI stopped 2-3 weeks before surgery.

• Allergies• Pregnancy- if surgery is necessary,

safe period- 2nd trimester.• Previous surgery & anaesthesia details.

Preoperative investigations

• Identify new problems to correct before surgery.

• Fitness for anaesthesia

• Avoid unnecessary tests

Investigations• FBC, Coagulation profile, • Cross match group & save.• Urea, electrolytes, LFTs• Microbiology- urine culture, sputum, virology• Imaging: CXR, US, CT, MRI, Isotope studies• RFT: ABG, FVC, FEV1 (Pulmonology consultation)

• CVS: ECG, Echocardiography, Thallium scan, exercise testing. (Cardiology consultation)

High risk patients

• HBV, HCV patients• HIV patients• Patients with unknown HBV,HCV,HIV status.• IV drug users• Recipients of multiple transfusion.• Patients from endemic area.• Universal precaution to protect surgical team.

Emergency surgery

• Assessment curtailed due to lack of time.• Frequently need resuscitation before surgery.• ABC approach.• Restore hypovolemia before surgery (except for

life threatening bleeders). • Avoid – delaying surgery to correct moderate

biochemical abnormalities.

Risk factors for VTE

• Malignancy• Age > 60 years• Dehydration• Past or family history of VTE• Obese• Significant comorbidity (CVS, RS, metabolic)• HRT, oestrogen containing contraceptives.• Pelvic or lower limb surgery• Surgery time > 90 min.

Preoperative round• Consent: Full explanation to patient and all

question answered.• Patient fully understands ( simple language)• All treatment options• All potential serious outcome, even if rare• Risk & benefit quantified• Surgeon or his deputy (knowledgeable, experienced)

• Respect patients decision• No pressure to accept recommendation

• Check all chronic/ acute conditions optimized.• DVT prophylaxis- anti embolic stockings,

intermittent pneumatic compression device, heparin (LMWH, unfractionated)

• Antibiotic prophylaxis.• Anxiolytics• Preoperative fasting- average 6 hours

Perioperative management of chronic disease

• CVS disease: Cardiology assessment. Antibiotic for valvular disease (BE prophylaxis) Pacemaker- avoid monopolar diathermy. Bipolar or ultrasonic devices preferred.

• RS: Chest physician consultation. May need HDU/ ICU- arrange bed in consultation with anaesthetist.

Pre/postop. chest physio.- incentive spirometry + good analgesia

Perioperative management of chronic disease

• Diabetes: Poor glycaemic control is associated with increased complication. Surgery → hyperglycaemia. Needs close monitoring.

• Glucose level- 6-10 mmol /L reasonable target.

• Management: • Omit oral hypoglycemic on morning of surgery, monitor sugar level

postop until eating freely (mild cases). If glucose > 10mmol/L- start glucose/insulin/K⁺ infusion

• Insulin dependent: Start glucose/ insulin/ K⁺ prior to surgery. Convert to- sc short acting insulin then regular insulin as the diet is introduced.

Chronic renal failure

• Dialysis dependent: Careful IV fluid administration.

• Care of dialysis access- PDC, venous fistula

• Venous fistula- never use for venous access/ phlebotomy.

• Preoperative dialysis to optimize patient.• Non-dialysis dependent: Reasonable renal function.

• Avoid: Nephrotoxic drugs, hypotension, treat sepsis aggressively and maintain careful fluid balance.

Jaundice

• Mostly obstructive, may be hepatocellular• Coagulopathy due to Vit K dependent factor

deficiency (II,VII,IX,X).• Coagulopathy corrected by FFP.

Anticoagulant therapy

• Warfarin stopped 4-5 days before surgery.• Started on IV unfractionated heparin or

subcutaneous low molecular weight heparin.• INR before surgery <1.5• Warfarin restarted after risk of bleeding is over,

concurrent with heparin.• Heparin stopped once INR 2.5-3.

Anaemia

• Mostly iron deficiency due to GI bleeding or menorrhagia.

• Preoperative haemoglobin around 10 G/ dl• If major blood loss expected- cell salvage

technique

Thank you!