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Preoperative assessment Yr 4 Anaesthesia Clerkship

Preoperative assessment Yr 4 Anaesthesia Clerkship. Dr Patricia Chalmers 2010-2011. O bjectives of preoperative assessment Fasting status The airway Volume status Systemic effects of anaesthetic agents Allergies and genetic considerations Risk Stratification

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Preoperative assessment Yr 4 Anaesthesia Clerkship

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  1. Preoperative assessmentYr 4 Anaesthesia Clerkship Dr Patricia Chalmers 2010-2011

  2. Objectives of preoperative assessment • Fasting status • The airway • Volume status • Systemic effects of anaesthetic agents • Allergies and genetic considerations • Risk Stratification • Respiratory and cardiovascular assessment • Patient sketches • Overview of history and examination

  3. Preoperative Assessment Objectives • To deliver good quality care • To establish doctor-patient rapport • To establish a clinical picture of the patient • To identify risk factors • To draw up a management plan • To optimise any concurrent medical conditions • To minimise the occurrence of critical incidents in the perioperative period

  4. Clinical Picture Full medical history and physical examination Points of specific relevance to anaesthesia: RISK STRATIFICATION General health of patient and functional capacity Surgical procedure Concurrent medical conditions and medication History of reactions and allergies to anesthesia THE AIRWAY Fasting Status Volume Status

  5. FASTING STATUS

  6. FASTING STATUS 6 hrs solids 4hrs liquids (2hrs clear fluid /water)

  7. The Full StomachMechanisms • Reflux • Delayed gastric emptying • Raised abdominal pressure • Pharyngeal and laryngeal incompetence

  8. The Full StomachClinical conditions • GORD • Opioids • Autonomic neuropathy: diabetes • Pregnancy • Intestinal obstruction • Trauma • Head Injury • Myopathies/ bulbar palsy

  9. Preoperative measures to reduce risk of aspiration • Proton pump inhibitors • H2 blockers • Metoclopramide • 0.3M Sodium citrate 30ml • Nasogastric tube where applicable (Induction of anaesthesia: RSI)

  10. THE AIRWAY

  11. THE AIRWAY • Examination Facial swelling • Mouth opening • Dentition • Macroglossia • MALLAMPATI GRADE • Thyromental distance • Neck shape and mobility

  12. Mallampati Grades

  13. Mallampati Grades

  14. Volume Status

  15. VOLUME STATUS Assess preoperative deficit Clinical picture Formula

  16. Volume Status TBW 70kg male 55-60% Body weight 45l Intracellular 30 L Extracellular 15 L interstitial 12L intravascular 3L

  17. Clinical Dehydration Body wt loss S&S 5% thirst, dry mouth 5-10% reduced peripheral perfusion, reduced skin turgor, oliguria, postural hypotension, tachycardia reduced CVP, lassitude, 10-15% inc RR, hypotension, anuria, delirium, coma >15% Life threatening

  18. Formula • 4mls/kg/hr for first 10 kg body weight • 2mls/kg/hr for the next 20kg body wt • 1ml/g /hr for every other kg body weight • Adult 2mls/kg/hr

  19. Fluid replacement • Replace existing deficit: 50% deficit in 1st hr, 25% in 2nd hr, 25% in 3rd hr • Maintain fluid balance 2mls/kg/hr • Deficit: fasting/ burns/GI losses • Consider ongoing losses

  20. Effects of anesthetic agents and drugs • Respiratory depression, impaired lung function →, HYPOXIA • Depressed myocardial function →HYPOTENSION arrthymias, • Impaired delivery of O2 to the tissues

  21. Effects of anaesthetic agents on respiratory function • Depression of RC • Diminished muscle tone • Reduced lung compliance(loss of elastic recoil)→ ↓TLC ↓TV ↓FRC and ↑Closing volume • Atelectasis • ↑Dead space(respiratory circuit)

  22. Increased work of breathing Increased ventilation /perfusion mismatch

  23. Effects of anaesthetic agents on cardiovascular function Reduced contractility Reduced stroke volume Vasodilatation Hypotension Risk of reduced coronary perfus perfusion

  24. Effects of anesthetic agents and drugs (contd) • Metabolism and elimination of drugs dependent on hepatic and renal function • Muscle relaxation and paralysis • Stress Response • Adverse effect on co-morbidities

  25. Perioperative Clinical Risks • Respiratory depression • Cardiac ischaemia • Arrthymias • Myocardial infarction • Stroke • Renal impairment

  26. Risk Stratification • ASA grades • Surgical procedure • Age • BMI • Elective v Emergency

  27. ASA GRADING 1. Healthy Patient 2.Mild systemic disease with no impact on life 3.Systemic disease with limiting factors 4. Systemic disease with a constant threat to life 5. Moribund patient

  28. Grading of General Surgical Procedures • Minor eg skin lesion 2. Intermediate eg inguinal hernia arthroscopy 3. Major eg hysterectomy, 4. Major+ eg colonic resection, radical neck dissection,

  29. Preoperative assessment • Is there any evidence of active disease? • Are there any clinical risk factors? • What is the patient’s functional capacity? • What maintenance medication is the patient on? • How can we optimise the patient’s clinical condition?

  30. Patient sketch 1 • 53 year old female for ligation of varicose veins • She has a history of asthma and neglects her medication • o/e anxious • RR 24/min • widespread rhonchi • PEF 65% • Other systems unremarkable

  31. Patient sketch 2 • 64 yr old male with intestinal obstruction for a laparatomy • History of COPD previous heavy smoker • Gets breathless walking uphill or fast on level ground • Coughing purulent sputum • FEV1 75% • On combined therapy with beta 2 agonist and anticholinergic

  32. Preoperative measures to improve lung function • Stop smoking • Chest physio • Bronchodilators • Antibiotics • Steroids

  33. Patient sketch 3 • 55yr old female for hysterectomy • Diabetic on twice daily insulin • BP 140/90 • What investigations and management

  34. Patient sketch 4 22 kg child for removal of plaster cast Fasting from midnight In theatre at 10.00am What is her fluid deficit?

  35. Patient Sketch 5 84 yr old female with a fractured neck of femur Tripped in bathroom lives alone and lay there for 20 hours She is thin stature, lives on tea, toast and cake History of CCF On diuretics ? Considerations and management

  36. Patient Sketch 6 40 yr old male for elective cholecystectomy Heavy smoker HR 80/min BP 200/115 Hb 14.0 gm/dl Urea 8 mmols/l Creatinine 140mmols/l

  37. Patient sketch 7 40 yr old male for cholecystectomy HR 80/min reg BP 150/95 Hb 12.8 gm/dl Urea 5.8 mmols/l Creatinine 115 µmols/l Na 130mmols/l K 4.5mmols/l

  38. Patient sketch 8 • 44 year old female for mastectomy and reconstruction • 5 year history of angina, becoming more frequent and increasing in severity over past 6 months • Both parents died from myocardial infarction • Coronary angiogram 2yrs ago no vessel disease • Ca antagonists,glyceryl trinitrate, isosorbide dinitrate, verapamil, Risk Factors Investigations Management

  39. Perioperative Cardiac Risk in relation to noncardiac surgery • Hi >5%: Vascular Aortic and peripheral vascular surgery • Intermediate 1-5%: intraperitoneal, intrathoracic, carotid endarterectomy, head and neck , orthopaedic, prostrate, • Lo risk <1%: endoscopic, superficial, cataract, breast, day stay procedures ACC/AHA 2007 guidelines

  40. Preoperative measures to improve cardiovascular status • Continue maintenance meds • Control heart failure • Stabilise arrthymias • Stabilise uncontrolled hypertension • Lo dose short acting beta-blockers for IHD if Hi or intermediate risk • Statins considered • Prophylactic antibiotics for valvular disease/prosthesis

  41. Systematic enquiry • RS • CVS • GIT HH GORD PUD • Renal system • Hepatic system • Endocrine diabetes thyroid • Bone joint and ct disorders RA • Haemotological anaemia coagulopathy DVT • Neurological and muscular epilepsy

  42. Systematic Enquiry (contd) • Medications Diuretics, Steroids, Diabetes, Epilepsy, Anticoagulants etc • Allergies • Social history Smoking, Alcohol • Previous Anaesthetic history PONV • FH genetic disorder SUX apnoea MH • Fasting status 6hrs (2hrs clear fluids)

  43. Investigations

  44. INVESTIGATIONS • FBC • U&E’S Where indicated • Group & Hold/X-match • ECG • CXR • Glucose • Coag screen (spinal, epidural) • BGA • Cardiac ultrasound • RFT’s

  45. Key Points (1) History: Full systemic history • Medications for maintenance • Allergies • Add previous anaesthetic history PONV • FH Sux apnoea, MALIGNANT HYPERTHERMIA FASTING status Anaesthetic Risk Stratification

  46. Key Points (2) Examination: Full systemic examination Add THE AIRWAY Consider Volume status G&H/X-match Obtain Consent Discuss pain management ---reassure Continue maintenance meds Draw up Anaesthetic Plan Bear in mind effects of anaesthesia on patient and effects of co-morbidities on the anaesthetic technique

  47. Recommended ReadingNeville Robinson, George Hall“How to Survive in Anaesthesia”BMJ Books 2nd Ed 2002

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