preoperative assessment yr 4 anaesthesia clerkship

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

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

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)

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)

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

24. 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

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

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)

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 Reading