Preoperative Assessment

Preoperative Assessment Overview

• Preoperative patient assessment includes their history and physical examination to determine which tests are appropriate.
• The main purpose of this assessment is to improve surgery and anesthesia outcomes.
• A consultation with an anesthetist is vital to assess a patient before surgery.
• Clinical assessment based on history and examination should happen first.
• Investigations follow if indicated.
• Preoperative assessment enables the identification of patients who require very few or no pre-op investigations or targeted or further assessments.

Objectives of Preoperative Assessment

• An identification of potential anesthetic difficulties.
• Identify any existing conditions.
• It’s important to improve safety by continually assessing and quantifying the risks.
• Allowance of planning of peri-operative care.
• Provides an opportunity for explanation and discussion to allay any fear and anxiety.

Goals and Benefits

• Primary goal includes detecting any unrecognized disease and risk factors.
• Necessary to detect anything that may increase surgical risk above baseline and propose risk reduction methods.
• The pre-op anaesthetic clinic is where patients with potential problems are seen early.
• Ideally the clinic should have a consultant anaesthetist or senior medical officer involved.
• The clinic should be equipped with staff, as well as X-ray and ECG equipment, and other pre-operative testing.

Key Questions for Pre-anaesthetic Screening

• Do you usually have chest pain or breathlessness when you climb two flights of stairs at a normal speed?
• Do you have kidney disease?
• Has anyone in your family had a problem following an anesthetic?
• Have you ever had a heart attack or stroke?
• Have you ever been diagnosed with an irregular heartbeat?
• If you have been put to sleep for an operation, were there any anesthetic problems?
• Do you suffer from epilepsy or seizures?
• Any problems with pain, stiffness, or arthritis in your neck or jaw?
• Do you have thyroid disease?
• Do you suffer from angina or liver disease?
• Have you ever been diagnosed with heart failure or asthma?
• Do you have diabetes that requires either insulin or tablets only?
• Do you suffer from bronchitis?

Assessment Components

• A patient's present and past medical and surgical history will need to be reviewed.
• A review of any drugs and anesthetic-related problems in the patient’s immediate family circle.
• Much of the risk associated with age can be attributed to comorbidities like cognitive or functional impairment, malnutrition, and frailty.
• Age should not be the only reason that guides preoperative testing or why a surgical procedure is withheld.

Family and Social History

• Family history includes malignant hyperthermia, pseudocholinesterase deficiency, and bleeding disorders
• Short term risks of smoking include incresed myocardial oxygen demand and decreased oxygen delivery
• Long term effect of smoking includes decreased immune function and decreased clearance

Medical History

• Drugs for hypertension and ischemic heart disease should be continued over the perioperative period.
• Past medical and surgical history has a direct effect on general and anesthetic treatment and outcome.
• It's important look for any previous operations or bleeding tendency as well as previous reactions to anesthetic agents.

Physical Examination

• Includes a full physical examination.
• It's important to omit no steps, because it adds to familiarizing what is normal so abnormalities can be recognized more easily.
• Don’t rely on the ex. of others; surgical signs may change and others may miss imp pathology

Physical Examinations Include:

• General exam including vitals
• Cardiac, respiratory and abdominal exam
• A CNS exam, musculoskeletal system, examination of the peripheral vasculature, and body orifices.

Emergency Physical Examinations

• Must be altered to fit the circumstances.
• Includes A, B, C, D, and E, as well as a secondary survey, head to toe.
• When emergencies present at the same time, it is important to triage.

Assessing Surgical Risk

• Overall risk is extremely low in healthy patients.
• Few patients are without risk for surgery.
• Quantifying risks involved is important so they can be discussed with patients.
• The two main prognostic scoring systems in use are the APACHE and ASA systems.

ASA System

• Stands for "American Society of Anesthesiologists."
• The system is simple and very widely accepted.
• 50% of patients presenting for elective surgery are in ASA Grade I.
• Operative mortality rate for these patients is less than 1 in 10,000.

ASA Predictive Mortality

• ASA Grade I refers to a normal healthy individual with a mortality percentage of 0.06.
• ASA Grade II refers to a mild systemic disease that doesn't limit activity, with mortality at 0.4%.
• ASA Grade III refers to a severe systemic that that limits activity, with mortality at 4.5%.
• ASA Grade IV refers to a severe systemic disease that is a constant threat to life, with mortality at 23%.
• ASA Grade V refers to a moribund patient, not expected to survive 24 hours with or without surgery, with mortality at 51%.

Clinical Predictors of Increased Risks

• Major predictors include acute or recent MI, unstable or severe angina, or strongly positive stress test.
• Additional predictors are decompensated heart failure, severe valvular disease, and significant arrhythmias.
• Intermediate predictors include mild angina or previous MI by history or Q waves.
• Can also include compensated heart failure, diabetes, and or renal insufficiency, with a creatinine above 2.0.
• Minor Predictors include advanced age, abnormal ECG, low functional capacity, history of stroke, uncontrolled systemic hypertension.

High, Intermediate and Low Risk Surgeries

• High-risk surgeries, above 5%, include emergent major surgeries and aortic or other vascular surgeries..
• Can also include peripheral vascular or prolonged surgeries.
• Intermediate risk surgeries, under 5%, include carotid endarterectomy and endovascular AAA repair.
• Includes head and neck procedures, as well as intra-peritoneal, and intra-thoracic, orthopedic or prostate procedures.
• Low risk surgeries, under 1% include endoscopic superficial cataract or breast surgery.

Optimizing Physical Status

• The assessment is completed by grading the surgery and classifying patients according to their ASA physical status.
• High-risk patients will require consultation with specialists to help optimize their physical status for surgery and anesthesia.

Rationale for Preoperative Investigation:

• To know the disease extent.
• Assessment for fitness for surgery, and exclusion of alternative diagnosis.
• To assess risk to others.
• Confirmation of diagnosis for medico-legal considerations.

Important Blood Tests

• Perform a full blood count in all emergency and elective pre-operative cases.
• Particularly important in cases in which patient is over 60, an adult female, and if significant blood loss is likely.
• Do so when there is a suspicion of blood loss or anemia, sepsis, and CKD.
• Check urea and electrolytes on pre-operative cases over 65.
• This is also for patients with cardiopulmonary disease, or a h/o renal/liver disease.

Important Blood Tests (continued)

• Check amylase in all adult emergency admissions with abdominal pain, prior to considering surgery.
• Assess random blood glucose in acute abdomen, elective DM cases, or in patients over 60.
• Conduct coagulogram studies for bleeding disorders, liver disease or excessive alcohol use.
• For cardio thoracic, vascular surgery, or craniotomy procedures.
• Order liver function tests in all patients with upper abdominal pain, jaundice, hepatic disease.
• Also if patients who are alcoholic.

Recommended Preoperative Chest X-rays

• Recommended for all elective pre-operative cases over 60 and if there is cervical, thoracic or abdominal trauma.
• Additionally to preformed for acute respiratory symptoms, viscous perforation, recent TB, or thyroid enlargement.

Cardiovascular System Evaluation

• A cardiovascular event is a significant contributor to perioperative noncardiac surgical mortality.
• Approximately 30% of all patients who undergo surgery in the US had coronary artery disease.
• Much of preoperative risk assessment and patient preparation stems from assessment of cardiovascular disease

Cardiac Risk Indices

• The Goldman Cardiac Risk Index, Detsky Modified Multifactorial Index, Eagle's Criteria, and Revised Cardiac Risk Index.
• A joint committee of ACC and AHA has developed a stepwise approach to preoperative cardiac assessment for non cardiac surgery, including the patient's coronary revascularization, major, intermediate, and minor clinical risk, and functional capacity.

High-Risk Cardiac Conditions

• Coronary revascularization and modification of choice of anesthetic.
• Invasive intraoperative monitoring.
• Patients having PCI with stenting should wait 4-6 weeks before deferring to elective procedure.
• Elective surgery after MI should also be postponed for 4 to 6 weeks.
• Medical therapy with beta blockers has been recommended as per ACC/AHA guidelines.

Pulmonary System Evaluation

• Pulmonary functions need to be assessed in cases involving lung resection and thoracic procedures.
• Important to measure any major abdominal and thoracic cases in patients over 60 years old.
• Also those who have underlying medical disease, smoke, or have overt pulmonary symptomatology.

Pulmonary System Factors

• Tests include forced vital capacity, and diffusing capacity of carbon monoxide.
• Adults with FEV1 less than 0.8 liter/sec, 30% of predicted, have high risk for complications and postoperative pulmonary insufficiency.

Patient Risk Factors for PPC

• General: >70 years, cigarette smoking, renal failure, poor nutrition
• Asthma related: recent attack, or past h/o endotracheal intubation for asthma management.
• Surgery and Anesthesia Related: emergent surgery.
• Also include thoracic vascular, upper abdominal surgery, blood loss over 2000ml, anesthesia time over 30 min.

Preoperative Interventions

• Smoking cessation within 2 months before the planned surgery.
• Incentive spirometry combined with encouraging a patient walk 3 miles in less than an hour several times weekly.
• Bronchodilator therapy.
• Antibiotic therapy for pre-existing infections, and pre-treatment for asthmatic patients.

Assessment of Renal Function Includes:

• History: congenital abnormality, obstructive uropathy, PCKD, recurrent UTI.
• Also include the presence of any underlying systemic disease, and any known renal sufficiency.
• Physical examinations reveals intravascular overload, petechie or ecchymosis, or lethargy.

Complications Assocated With Renal Conditions:

• Altered fluid and electrolyte balance, hypertension, peripheral edema, and electrolyte imbalance.
• Hematological dysfunction, like anemia, coagulation defects, altered platelet adhesion and aggregation.
• Altered calcium and parathyroid metabolism.

Preoperative Optimizations for Patients with Renal Issues

• Anemia treated with erythropoietin or darbepoietin.
• Any hyperkalemia is manipulated and calcium is replaced.
• Phophate binding antacids and sodium bicarbonate can be given.
• Hyponatremia treated by fluid restriction; nephrotoxic drugs are avoided.
• Preoperative dialysis is recommended to be done about 24 hours before.
• Coagulopathy can be treated with adequate dialysis and FFP.

Hepatobiliary System Function

• Consider prior history of jaundice, hepatitis, anemia, parasitic infection, enzyme deficiency, or malignancy. Consider drug an alcohol abuse or exposures to infectious agents or hepatoxins.

Indications of Liver Damage

• Jaundice, Ascites, peripheral edema, muscle wasting, or testicular atrophy
• Other stigmata includes evidence of bleeding disorder

Lab Evaluations for Liver Function

• Liver Function Tests, CBC, Serum Electrolytes, Coagulogram.
• For patients with cirrhosis, consider the Child-Pugh Scoring system

Child-Pugh Scoring System

• Class A: 5-6 points, mortality rate of 10%.
• Class B: 7-9 points, mortality rate of 31%.
• Class C: 10-15 points, mortality rate of 76%.
• It stratifies the operative risk in patient with cirrhosis.

Diabetes Evaluation

• Key things to evaluate about diabetes mellitus includes history, examination, and glycemic control.
• Key tests evaluate fasting and postprandial blood glucose, HBA1C, Serum electrolytes BUN, and creatinine.
• Evaluation includes urine analysis and assessment via ECG.

Preoperative Optimizations for Patients with Diabetes

• The morning dose of Oral Hypoglycemic Agents must be be omitted. 
• The patient should be started on variable rate intravenous insulin infusion, between 140-180 mg/dl.
• Schedule cases first and defer the elective surgery until achieving good glycemic control.

Thyroid Conditions and Surgery

• Elective Surgery should be deferred until a euthyroid state is achieved, and serum electrolytes measured.
• Anti-thyroid drugs and B-blockers should be continued on the day of surgery.
• In emergency surgery for those with thyrotoxicosis, ensure a combination of beta-blockers and glucocorticoids or other medications.

Treating Hypothyroidism

• Severe hypothyroidism can cause MI as well as coagulation defects. Ensure electrolytes balance.
• Elective surgery should also be deferred until a euthyroid state is achieved.
• For Patients with H/O Steroid Use/ Suppression Of HPAA.
• Those who have taken >5mg of Prednisolone or equivalent are at risk when underdoing major surgery.
• The amount of medicine a patient should be on varies depending on if they are having a minor (no additional streroid), moderate (50-75 mg/day of hydrocotisone), or Major operation (100-150mg/day hydrocortisone).

Important Evaluation for Anemia

• Hematologic assessment identifies presence of anemia, neutropenia, coagulopathy, and hypercoagulable state.
• Often, this diagnosis can be asymptomatic with an examination that reveal energy loss and shortness of breath.
• Evaluation for this should include examining lymph nodes, assessing liver and spleen.

Evaluating the Blood

• Key to do a CBC, reticulocyte count, serum iron, TIBC, ferritin, Vit B12, and folate levels for possible causes.

Healthy Individuals During Surgery

• Healthy patients should have anticipated blood loss of 6.0 - 7 g/dl.
• Patients with cardiac or pulmonary disease should have blood loss of 10g/dl.
• In elective cases, the reversible cause of anemia should be corrected before delay.
• Blood transfusions may be also required if non correctable cause of surgery and in the case of emergency surgeries.

Managing Patients on Blood Thinners

• Require preoperative reversal of anticoagulant effect.
• Warfarin should be held for 5 days preoperatively to reduce INR to 1.5 or less.
• Those at risk of VTE are recommended to have full bridging while off anticoagulation.
• For LMWH, the last does should be given 20-24 hours prior to surgery.
• The blood thinner should be restarted about 12-24 hours post-operatively.

Anticoagulation Indications

• If patients has prosthetic valves or chronic A Fib.
• It's important to assess risk and ensure optimal management.

Diagnosing and Assessing a Coagulopathy

• May come from an inherited or acquired platelet or factor disorder, organ dysfunction, or medications.
• Ask for Personal & family medical history or easy bruising.
• Key post-op risks includes liver disease and malnutrition.
• Key workup with include complete heogram and labs.

In Vit K deficiency

• If patient has mild liver disease, PT will be prolonged.
• If the deficiency is severe, PT and aPPT will tend to prolong.
• Haemophilia - aPPT is normally prolonged but PT is ok.
• For DIC you can increase d-dimer.

When Managing Bleeding

• Severely factor deficient patient need FFP and cryo as soon as possible.
• Transfuse platelets for low/abnormal tests.
• One unit of platelet count is increased by 5,000-10,000.

Managing Heparin Intake

• For patients with Heparin who need surgery.
• Discontinue Heparin for 6 hrs prior to the procedure.
• Use protamine sulphate if an emergency arises.

Nutritional Assessment

• Must assess and evaluate for this pre-operatively.
• Malnutrition increases infection, delayed wound healing, sepsis and pneumonia.
• Asses for patients recent weight loss, muscle bulk, and bowel habits.
• Assess specifically IBS,. bulimia and anorexia.
• Formula: Nutril risk assessment, SR albumin * + pre-existing.
• An NRI result under 83% is correlated with increased mortalitiy.