Preoperative Assessment PDF

PREOPERATIVE ASSESSMENT Dr. Aye Thandar Htun  INTRODUCTION Preoperative visit - is an essential requirement for the safe and successful conduct of anaesthesia To identify associated medical illness and anaesthetic risks with the ultimate aim of reducing morbidity...

PREOPERATIVE ASSESSMENT Dr. Aye Thandar Htun  INTRODUCTION Preoperative visit - is an essential requirement for the safe and successful conduct of anaesthesia To identify associated medical illness and anaesthetic risks with the ultimate aim of reducing morbidity and mortality  Why is Preoperative Assessment Important?  Anesthetic drugs and techniques - profound effects on human physiology  Focused review of all major organ systems should be completed prior to surgery. LeNs respiration ,  Goals of the preoperative evaluation - to ensure that the patient is in the best (or optimal) condition  Patients with unstable symptoms - postponed for optimization prior to elective surgery  Emergent surgery in an unstable patient -risks should be weighed against benefits of proceeding with ongoing resuscitation  Objectives To evaluate and optimize the patient’s medical condition 14 before (plan) -book To plan anaesthetic technique and peri-operative care To develop a rapport with the patient to allay anxiety and facilitate conduct of anaesthesia To allow appropriate discussion with patient/guardian To obtain informed consent Definition of Timing of Surgery UK organization  Key Components of Preoperative Assessment ❖ Problem Identification – Focused history & examination – Review of investigations – Result/response to treatment so far ❖ Risk Assessment ❖ Plan of Anesthetic technique – Pre operative – Intra operative – Post operative  GENERAL PRINCIPLES Mo Personnel - sep preop clinic min by Place in ull disease Timing depends on pt condition Preoperative admission Multi-disciplinary management pt i u/l disease , joint my Emergency surgery  Process of preoperative evaluation  1. History  2. Physical examination  3. Laboratory evaluation  4. Prediction of perioperative morbidity and mortality ↓  5. Documentation – informed consent follow ASA guideline - preoperative note ASA- American Society of Anaesthesiologist  1. Preoperative History (including review of medical records) (a) Presenting condition and concurrent medical history - eg. Bowel cancer malnourishment, anaemia, electrolyte imbalance - coexisting medical d/s cvs and respiratory systems – most important - angina, previous MI, heart failure, hypertension - preexisting lung d/s, RTI postponed if ada - indigestion, heartburn ↑ risk of aspiration - rheumatoid disease - diabetes autonomic heuropathy - renal d/s affect pharmacology anaesthetic drug  Assessment of capacity of cardiorespiratory system  Metabolic equivalent (MET) levels for readily assessed activity levels  The ratio of metabolic rate (the rate of energy consumption) during a specific physical activity to a reference metabolic rate, set by convention to 3.5 ml O2·kg−1·min−1. (The ratio of the work metabolic rate to the resting metabolic rate.) MET score Approximate level of ↓ chance of ↓ getting activity cardiorespiratory complication 1 Dress, walk indoors if pt is 24 2 Light housework, slow walk 4 * Climb two flights of stairs, run a short distance 6 Moderate sport, eg. Golf, doubles tennis or dancing 10 Strenuous sports or exercise NYHA Classification (b) Planned surgical procedure - can predict for Appendicectomy, need to discuss in r are surgery , surgeon (c) Medication history - Generally most long term medication should be continued upto the morning of operation - Drug interaction anti APT can cont until morning of surgery G ACE-I can worsen APT , other anti HpT can cont (d) Previous operations and anaesthetic history - Examine anaesthetic record GA/ regional - - Exposure to halothane avoid 3 before another exposure/hepatotuacity, - m ginseng) before Stop 1 : 2 w herbal med /garlic , ginko , surgery (f) Family history trigger factor - History of prolonged apnoea, malignant hyperpyrexia Chalothane ↳ after surgery be careful succiny/choline - can have prolonged aphea Medications that may have interaction with anaesthetic agents Drug group Comments ACEI Potent vasodilators. Synergistic with the effects of anaesthetics causing hypotension Antibiotics: aminoglycosides Synergistic with neuromuscular blocking drugs Anticoagulants Increased risk of haemorrhage d/r intubation, local anesthesia, surgery, insertion of nasogastric tube Anticonvulsant Potent inducer of hepatic enz:, may need increase dose of induction agents and opioids Benzodiazepines Additive effect with other CNS depressants Beta blockers Negative inotropic effects may combine with vasodilatation caused by anaesthetic agents to produce hypotension. Pulse rate is poor guide to blood loss intraop: Calcium antagonists Effects additive to inhalational agents causing hypotension Diuretics Hypokalaemia causing dysrhythmias and prolonging neuromuscular blockade (g) Social history risk of brunche constriction Smoking - Nicotine – tachycardia, hypertension - CO – Hb to carboxyHb ----- reduce O2 carriage - Stop x 6 weeks ---- reduce bronchoconstriction and mucus secretion - Stop x 12 hr ---- increase in arterial O2 content Alcohol ↑ dose of anaes agent - Causes induction of liver enzymes - Increase MAC in chronic alcoholic minimal alveolar concentration  2. Physical Examination System Features of interest General Nutritional state, fluid balance Condition of the skin and mucous membranes(anaemia, perfusion, jaundice) Temperature Cardiovascular Peripheral pulse(rate, rhythm, volume) Arterial pressure Heart sounds Dependent oedema Respiratory Cyanosis Observation of dyspnoea Auscultation of lung fields AirwayR Mouth opening still need to assess in case of Neck movements Thyromental distance hand to change to GA from regional Dentition Nervous Conscious level, any neurological deficit  Anatomical factors associated with difficult laryngoscopy Short , muscular neck Protruding incisors (buck teeth) Receding lower jaw Poor mobility of mandible Decreased atlanto-occipital distance (reduces neck extension, requires X-ray) 1) airay assessment  ask pt in sit position neutral head protunde tongue maxi Class I – Visualization of soft palate, uvula, pillars Class II – Visualization of soft palate, uvula 3 normal Class III – Visualization of soft palate, base of uvula ! Class IV – Only hard palate is visible. Soft palate is not visible at all. diff intubation but need to combine in other assessmental  Thyromental Distance (TMD) Thyromental distance (Patil’s test) Thyroid cartilage prominence to the bony point of the chin d/r full head extension (N > 6.5 cm) > 3 finger breadths  Sterno-mental distance Sterno-mental distance (Savva test) N > 12 cm  Inter-incisors distance  3 fingers  Inter-incisor distance with maximal mouth opening  Minimum acceptable value > 4 cm Significance :  Easy insertion of a 3 cm deep flange of the laryngoscope blade  < 3 cm: difficult laryngoscopy  < 2 cm: difficult LMA insertion  Affected by TMJ and upper cervical spine mobility  Cormack-Lehane classification view not minical examination/bed side , lanygoscopy normal Sait I  Upper Lip Bite Test  Class I: Lower incisors can bite the upper lip above vermilion line  Class II: can bite the upper lip below vermilion line  Class III: can not bite the upper lip Significance  Assessment of mandibular movement and dental architecture  Less inter observer variability  LEMON Rule Look Facial injury, large incisors, large tongue, beard Evaluate 3-3-2 finger breadth measurement Inter incisor Hyoid –mental Thyroid to floor of mouth Mallampati Score ≥ 3 Obstruction Any condition causing obstruction (Epiglottis, peritonsillar abscess, trauma) Neck Limited neck mobility  Quick airway assessment 1. Can the patient open the mouth widely? - Indicative of TM joint movement. 2. Can the patient maximally protrude the tongue? - Inspects posterior aspect of mouth/pharyngeal structures. 3. Patient’s ability to move jaw forward? - Indicates ease to manoeuver the laryngoscope. 4. Can patient fully bend/extend the head and move it side wards? - Indicates neck movements.  Predictors of difficulty to face mask ventilate (OBESE) 1. Obese 2. Bearded 3. Elderly second cheek 4. Snorers 5. Edentulous no teeth  3. Laboratory Evaluation - No unnecessary investigations - Only order if the result will affect management - Healthy patient undergoing short, minimally invasive procedures – Ivx may not be necessary  For asymptomic patients without abnormal findings guideline MSA For patients with abnormal clinical findings Investigation Indications Full blood count 1. Anaemia 2. Other haematological disease 3. Renal disease Renal profile 1. Renal disease 2. Liver disease 3. Cardiovascular disease 4. Diabetes mellitus 5. Abnormal nutritional status 6. History of diarrhea, vomiting 7. Preoperative bowel preparation Blood glucose 1. Diabetes mellitus 2. Severe liver disease ECG 1. Heart d/s, hypertension or chronic pulmonary d/s 2. Diabetes mellitus 3. Renal disease Chest X-ray 1. Significant respiratory disease 2. Cardiovascular disease 3. Malignancy Arterial blood gas 1. Debilitated or septic patients 2. Moderate or severe pulmonary d/s Coagulation screen 1. Haematological disease 2. Severe liver disease 3. Patients on anticoagulant therapy Liver function tests 1. Hepatobiliary disease 2. History of alcohol abuse 3. Tumour with possible metastases to liver  Period of validity FBC, urea, renal 1 week profile, blood glucose ECG 1 month CXR 6 months  Risk Assessment Components for evaluating perioperative risk: Patient's medical condition preoperatively Extent of the surgical procedure Risk from the anesthetic “Clear the patient for surgery”  4. Prediction of perioperative morbidity and mortality ASA PHYSICAL STATUS CLASSIFICATION ASA rating Description American Society of Anaesthesiologist Mortality rate (%) Class I A normal healthy individual 0.1 % who U1L disease preg Class II A patient with mild systemic disease with no significant impact on 0.2 % daily activity, e.g. mild diabetes, controlled hypertension, obesity -myou/l Bm1330 disease Class III A patient with severe systemic disease that is not incapacitating, 1.8 % e.g. angina, COPD, prior myocardial infarction BM13 40, Class IV A patient with incapacitating systemic disease that is a constant 7.8 % threat to life, e.g. CHF, unstable angina, renal failure ,acute MI, respiratory failure requiring mechanical ventilation ↳ 6 m/ly ago Class V A moribund patient who is not expected to survive 24 hr without 9.4 % operation, e.g. ruptured aneurysm M1 in 3m (recent) Class VI Brain-dead patient whose organs are being harvested Class E Added as a suffix for emergency operation  Goldman’s Cardiac Risk Index (cardiac risk index in non-cardiac surgery) PATIENT RISK FACTORS POINTS Third heart sound or gallop rhythm 11 MI in preceding 6 mth 10 Nonsinus rhythm or atrial ectopic 7 beats on electrocardiogram >5 ventricular ectopic per minute 7 Age >70 yr 5 Emergency operations 4 Poor general medical condition (PO2 50 mmHg; K 270 umol/L; elevated liver enzymes; chronic liver disease; bedridden) Intrathoracic, intraperitoneal, or 3 aortic surgery Important valvular aortic stenosis 3 Goldman’s Cardiac Risk Index Class Life threating complication I (0-5) 0.7 % II (6-12) 5% III (13-25) 11% IV (>26) 22% not mandatory for CP Risks According to Type of Surgery  Postponing surgery  A/c URTI  Coexisting medical d/s  Emergency surgery----- only 1-2 hr for resuscitation  Recent ingestion of food  Failure to obtain consent  Preoperative fasting guideline Solid food – 6 hr (heavy - 8 hr) Milk (infant formula) – 6 hr Breast milk – 4 hr Clear fluid – 2 hr (clear fluids include water, glucose drink, cordial drink, clear fruit juice) 2025. 44-ne a  zmuth left 1 , 5. Documentation Informed consent year - reasonable explanation of the options - sufficient information about the procedures and risks informed - written consent Preoperative note - history - physical examination - laboratory results - ASA classification - recommendations of any consultants - anesthetic plan - informed consent  Stages in the consent process Ensure competence (ensure that the patient can take in, analyse and express their view) Check details (correct patient) Make sure that the patient understands who you are and what your role is Discuss the treatment plan and sensible alternatives Discuss possible risks and complications (especially those specific to the patient)  Discuss the type of anaesthetic proposed Give the patient time and space to make the final decision Check that the patient understands and has no more questions Record clearly and comprehensively what has been agreed Period of validity of consent - No more than 7 days? - The consent obtained is valid as long as the patient’s condition remains the same. > MMC if pt deteriorate take new consent - , - Should there be a change in the nature and clinical course and presentation of the illness - a new consent must be obtained from the patient In order for consent to be valid, it must have 3 elements: 1. The patient must have capacity to consent to the treatment offered. 2. The patient must have sufficient information to enable him/her to make a balanced decision to consent. 3. The consent must be voluntary. Factors for selection of anaesthetic technique Safety of patient Coexisting systemic disorders Site of operation eg :below umbilius > - spinal anesthesia Age of patient Preference of patient Ability of anaesthetist concerned Preanaesthetic routine preparation Psychological support, reassurance Fasting Urinary bladder should be emptied before OT False teeth – taken off No lipstick, no nail varnish Identification label – check Consent – mandatory Premedication  Premedication Administration of drugs in 1-2 hr before induction can give at night before not mandatory for every pt Objectives (6A) ❖ Anxiolysis - benzodiazepines ❖ Amnesia - benzodiazepines ❖ Anti-emetic – dopamine antagonists, 5 HT3 antagonists ❖ Aspiration prophylaxis – sodium citrate, H2 antagonists, metoclopramide ❖ Anti-autonomic – atropine, glycopyrrolate, beta-blockers ❖ Analgesic – morphine, pethidine, fentanyl  Premedication drugs Benzodiazepines MOA  Facilitate the inhibitory effects of GABA Effects  Anxiolysis, sedation, amnesia, antiepileptic activity  No analgesic properties  Mild muscle relaxation  Dose-related respiratory depression  Decrease in systemic vascular resistance – small decrease in BP Ultra-short Short-acting Intermediate- Long- acting acting acting Midazolam Zopiclone Alprazolam Diazepam preferable Zolpidem Temazepam Flurazepam Lorazepam  Anticholinergic for this not use purpose anymore ↑  To decrease salivary and respiratory secretions reye surgery  To counteract vagal reflex, reversal of neuromuscular blockade · atropine/gly copywolate (combination with neostigmine) L to ↓ SE of neostigmine Atropine  0.4-0.6 mg IV  Tachycardia, bronchodilation, dry mouth, mydriasis  High dose – sedation, excitation, hallucination  Anticholinergic Glycopyrronium bromide (Glycopyrrolate) 0.2-0.3 mg IV Cannot cross BBB – devoid of CNS and ophthalmic INS SE activity no Minimal CVS effects than atropine  post up nausea & vomiting Antiemetic (PONV prophylaxis) Metoclopramide  IV Metoclopramide 10 mg  Potent antiemetic effect  Increase the rate of gastric emptying  No significant effect on gastric secretion and acidity Antiemetic (PONV prophylaxis) Ondensetron/ granisetron IV Ondansetron 4 mg/ granisetron 1 mg Highly effective for prevention and treatment of PONV Selective 5-HT3 receptor antagonist  Aspiration prophylaxis Premed given asI Indications when reg  Pregnancy  Morbid obesity  Hiatus hernia  Large abdominal mass  Gastro oesophageal reflux desease · 10 of drug combination neutralize residual g Antacid – sodium citrate (30 min bf GA) to ad secretion H2 antagonist – ranitidine, cimetidine ↓ gastric Proton pump inhibitor – omeprazole, pantoprazole Prokinetics - metoclopramide not for powv but for aspiration prophy  Plan of Anaesthesia Local or Regional anesthesia with 'standby‘ monitoring with or without sedation. General anesthesia; with or without intubation. Spontaneous or controlled ventilation? Combined regional with general anesthesia  eg : emer pt ~ Llaryngeal mask airway  Preoperative evaluation ❖ Not only to gather important information and obtain informed consent, but also to help establish a healthy doctor-patient relationship. ❖ Visit of anaesthesiologist ~ Premedication