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Anaesthesia for Patients with COPD Dr Sajith Damodaran University College of Medical Sciences & GTB Hospital, Delhi Slide 2 COPD: PATHOPHYSIOLOGY, DIAGNOSIS, TREATMENT Slide 3 Chronic Obstructive Pulmonary Disease Definition: Disease state characterised by airflow limitation that is not fully reversible The airflow limitation is usually progressive and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking. Slide 4 Chronic Obstructive Pulmonary Disease Definition: Disease state characterised by airflow limitation that is not fully reversible The airflow limitation is usually progressive and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking. Slide 5 COPD: Includes: Chronic Bronchitis Emphysema Peripheral Airways disease Doesnt include Asthma, Asthmatic Bronchitis Cystic Fibrosis Bronchiactesis Pulmonary fibrosis due to other causes Slide 6 COPD Chronic Bronchitis: (Clinical Definition) Chronic productive cough for 3 months in each of 2 successive years in a patient in whom other causes of productive chronic cough have been excluded. Emphysema: (Pathological Definition) The presence of permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis Slide 7 Comparative features of COPD FeatureChronic BronchitisEmpysema Mech of Airway Obstruction Decreased Lumen d/t mucus & inflammation Loss of elastic recoil DysnoeaModerateSevere FEV 1 Decreased PaO 2 Marked Decrease (Blue Bloater) Modest Decrease (Pink Puffer) PaCO 2 IncreasedNormal or Decreased Diffusing capacityNormalDecreased HematocritIncreasedNormal Cor PulmonaleMarkedMild PrognosisPoorGood Slide 8 COPD: Risk factors Host factos: Genetic factors: Eg. 1 Antitrypsin Deficiency Sex : Prevalence more in males. ?Females more susceptible Airway hyperactivity, Immunoglobulin E and asthma Exposures: Smoking: Most Important Risk Factor Socioeconomic status Occupation Environmental pollution Perinatal events and childhood illness Recurrent bronchopulmonary infections Diet Slide 9 Natural History: Fig. 1. - The normal course of forced expiratory volume in one second (FEV1) over time () is compared with the result of impaired growth of lung function ( ) an accelerated decline () and a shortened plateau phase (). All three abnormalities can be combined (Kerstjens HAM, Rijcken B, Schouten JP, Postma DS. Decline of FEV1 by age and smoking status: facts, figures, and fallacies. Thorax 1997; 52: 820827.) Slide 10 Pathophysiology: Pathological changes are seen in 4 major compartments of lungs: central airways Peripheral airways lung parenchyma pulmonary vasculature. Slide 11 Pathophysiology: Central Airways: (cartilaginous airways >2mm of internal diameter) Bronchial glands hypertrophy Goblet cell metaplasia Airway Wall Changes: Inflammatory Cells Squamous metaplasia of the airway epithelium Increased smooth muscle and connective tissue Peripheral airways (noncartilaginous airways55% History of edema 60 90 None except with qualifier Exercise desaturation Sleep desaturation not corrected by CPAP Lung disease with severe dyspnea responding to O2 Slide 23 Treatment: Symptomatic Measures Bronchodilators: Anticholinergics Beta Agonists Methylxanthines Corticosteroids N-Acetyl Cysteine 1 Antitrypsin augmentation Vaccination Others: No proven effect Leukotriene receptor antagonists/cromones Maintenance antibiotic therapy Immunoregulators Vasodilators: NO, CCB Slide 24 Surgical Treatment Bullectomy short-term improvements in airflow obstruction lung volumes hypoxaemia and hypercapnia exercise capacity dyspnoea Lung Volume Reduction Surgery potentially long-term improvement in survival short-term improvements in Spirometry lung volumes exercise tolerance dyspnoea Lung Transplantation Slide 25 COPD: Exacerbations Definition: An exacerbation of COPD is an event in the natural course of the disease characterised by a change in the patients baseline dyspnoea, cough and/or sputum beyond day-to-day variability sufficient to warrant a change in management. Precipitating Causes: Infections: Bacterial, Viral Air pollution exposure Non compliance with LTOT Slide 26 COPD: Exacerbations Indication for Hospitalisation : The presence of high-risk comorbid conditions pneumonia, cardiac arrhythmia, congestive heart failure, diabetes mellitus, renal or liver failure Inadequate response to outpatient management Marked increase in dyspnoea, orthopnoea Worsening hypoxaemia & hypercapnia Changes in mental status Uncertain diagnosis. Slide 27 COPD: Exacerbations Indication for ICU admission: Impending or actual respiratory failure Presence of other end-organ dysfunction shock renal failure liver failure neurological disturbance Haemodynamic instability Slide 28 Treatment Supplemental Oxygen (if SPO 2 < 90%) Bronchodilators: Nebulised Beta Agonists, Ipratropium with spacer/MDI Corticosteroids Inhaled, Oral Antibiotics: If change in sputum characteristics Based on local antibiotic resistance Amoxycillin/Clavulamate, Respiratory Flouroquinolones Ventillatory support: NIV, Invasive ventillation Slide 29 Optimal disease management entails redesigning standard medical care to integrate rehabilitative elements into a system of patient self-management and regular exercise Optimal disease management entails redesigning standard medical care to integrate rehabilitative elements into a system of patient self-management and regular exercise In a nutshell Slide 30 . PREPARATION FOR ANAESTHESIA Slide 31 Anaesthetic Considerations in patients with COPD undergoing surgery: Patient Factors: Advanced age Poor general condition, nutritional status Co morbid conditions HTN Diabetes Heart Disease Obesity Sleep Apnea Weak HPV, blunted Ventilatory responses to hypoxia and CO 2 retention Slide 32 Age Related Pulmonary Changes: Pathological changesEffectImplications Decreased efficiency of lung parenchyma Decreased VC Increased RV Respiratory Failure Decreased Muscle strength Decreased Compliance, FEV 1 Poor cough Infection Alveolar septal destruction Decreased alveolar areaDecreased gas exchange Brohchiolar damageIncreased closing volumeAir trapping Decreased PaO 2 Dilated upper airwaysIncreased V D Decreased gas exchange Decreased reactivityDecreased laryngeal reflexes Decreased vent response to hypoxia, hypercarbia Increased Aspiration Increased resp. failure Slide 33 Anaesthetic Considerations in patients with COPD undergoing surgery: Problems due to Disease Exacerbation of Bronchial inflammation d/t Airway instrumentation preoperative airway infection surgery induced immunosuppression increased WOB Increased post operative pulmonary complications Slide 34 Anaesthetic Considerations in patients with COPD undergoing surgery: Problems due to Anaesthesia: GA decreases lung volumes, promotes V/Q mismatch FRC reduced during anaesthesia, CC parallels FRC Anaesthetic drugs blunt Ventilatory responses to hypoxia & CO 2 Postoperative Atelectasis & hypoxemia Postoperative pain limits coughing & lung expansion Problems due to Surgery: Site : most important predictor of Post op complications Duration: > 3 hours Position Slide 35 Pre-operative assessment: History: Smoking Cough: Type, Progression, Recent RTI Sputum: Quantity, color, blood Dyspnea Exercise intolerance Occupation, Allergies Symptoms of cardiac or respiratory failure Slide 36 Pre-operative assessment: Examination Physical Examination: Better at assessing chance of post op complications Airway obstruction hyperinflation of chest, Barrel chest Decreased breath sounds Expiratory ronchi Prolonged expiration: Watch & Stethoscope test, >4 sec WOB RR, HR Accessory muscles used Tracheal tug Intercostal indrawing Tripod sitting posture Slide 37 Body Habitus Obesity/ Malnourished Active infection Sputum- change in quantity, nature Fever Crepitations Respiratory failure Hypercapnia Hypoxia Cyanosis Cor Pulmonale and Right heart failure Dependant edema tender enlarged liver Pulmonary hypertension Loud P 2 Right Parasternal heave Tricuspid regurgitation Pre-operative assessment: Examination Slide 38 Preoperative Assessment: Investigations Complete Blood count Serum Electrolytes Blood Sugar Urinalysis ECG Arterial Blood Gases Diagnostic Radiology Chest X Ray Spiral CT Preoperative Pulmonary Function Tests Tool for optimisation of pre-op lung function Not to assess risk of post op pulmonary complications Slide 39 Investigations: Chest X-Ray Overinflation Depression or flattening of diaphragm Increase in length of lung size of retrosternal airspace lung markings- dirty lung Bullae +/- Vertical Cardiac silhouette transverse diameter of chest, ribs horizontal, square chest Enlarged pulmonary artery with rapid tapering in MZ Slide 40 Pulmonary Function Tests: MeasurementNormalObstructiveRestrictive FVC (L)80% of TLC (4800) FEV 1 (L)80% of FVC FEV 1 /FVC(%)75- 85% N to N to FEV 25%-75% (L/sec)4-5 L/ sec N to PEF(L/sec)450- 700 L/min N to Slope of FV curve MVV(L/min)160-180 L/min N to TLC6000 ml N to RV1500 mL RV/TLC(%)0.25 N Slide 41 FEV1 FVC seconds 21345 0 1 2 3 4 Litres 5 COPD NORMAL 60%39002350COPD 80%52004150Normal FEV1/FVCFVCFEV1 FVC Spirometric tracing in COPD patients Slide 42 Maximum inspiratory and expiratory flow-volume curves (i.e., flow-volume loops) in four types of airway obstruction. Slide 43 Preoperative Assessment: Investigations ECG Signs of RVH: RAD p Pulmonale in Lead II Predominant R wave in V 1-3 RS pattern in precordial leads Arterial Blood Gases: In moderate-severe disease Nocturnal sample in cor Pulmonale Increased PaCO 2 is prognostic marker Strong predictor of potential intra op respiratory failure & post op Ventilatory failure Also, increased d/t post op pain, shivering, fever,respiratory depressants Slide 44 Pre-operative preparation Cessation of smoking Dilation of airways Loosening & Removal of secretions Eradication of infection Recognition of Cor Pulmonale and treatment Improve strength of skeletal muscles nutrition, exercise Correct electrolyte imbalance Familiarization with respiratory therapy, education, motivation & facilitation of patient care Slide 45 Effects of smoking: Cardiac Effects: Risk factor for development of cardiovascular disease CO decreases Oxygen delivery & increases myocardial work Catecholamine release, coronary vasoconstriction Decreased exercise capacity Respiratory Effects: Major risk factor for COPD Decreased Mucociliary activity Hyperreactive airways Decreased Pulmonary immune function Other Systems Impairs wound healing Slide 46 Smoking cessation and time course of beneficial Effects Time after smokingPhysiological Effects 12-24 HrsFall in CO & Nicotine levels 48-72 HrsCOHb levels normalise Airway function improves 1-2 WeeksDecreased sputum production 4-6 WeeksPFTs improve 6-8 WeeksNormalisation of Immune function 8-12 WeeksDecreased overall post operative morbidity Slide 47 Dilatation of Airways: Bronchodilators: Only small increase in FEV 1 Alleviate symptoms by decreasing hyperinflation & dyspnoea Improve exercise tolerance Anticholinergics Beta Agonists Methylxanthines Slide 48 Anticholinergics: Block muscarinic receptors Onset of action within 30 Min Ipratropium 40-80 g by inhalation 20 g/ puff 2 puffs X 3-4 times 250 g / ml respirator soln. 0.4- 2 ml X 4 times daily Tiotropium - long lasting Side Effects: Dry Mouth, metallic taste Caution in Prostatism & Glaucoma Slide 49 Beta Blockers: Act by increasing cAMP Specific 2 agonist Salbutamol : oral 2-4 mg/ 0.25 0.5 mg i.m /s.c 100-200 g inhalation muscle tremors, palpitations, throat irritation Terbutaline : oral 5 mg/ 0.25 mg s.c./ 250 g inhalation Salmeterol : Long acting (12 hrs) 50 g BD- 200 g BD Formeterol, Bambuterol Slide 50 Bronchodilators: methylxathines Mode of Action inhibition of phospodiesterase, cAMP, cGMP Bronchodilatation Adenosine receptor antagonism Ca release from SR Oral(Theophyllin) & Intravenous (Aminophylline, Theophyllin) loading 5-6 mg/kg Previous use 3 mg/kg Maintenace 1.0mg/kg h for smokers 0.5mg/kg/h for nonsmokers 0.3 mg/kg/h for severely ill patients. Slide 51 Inhaled Corticosteroids: Anti-inflammatory Restore responsiveness to 2 agonist Reduce severity and frequency of exacerbations Do not alter rate of decline of FEV 1 Beclomethasone, Budesonide, Fluticasone Dose: 200 g BD upto 400 g QID > 1600 g / day- suppression of HPA axis Slide 52 . ANAESTHETIC TECHNIQUE Slide 53 Anaesthetic Technique COPD is not a limitation on the choice of anaesthesia. Type of Anaesthesia doesnt predictably influence Post op pulmonary complications. Slide 54 Concerns in RA Neuraxial Techniques: No significant effect on Resp function: Level above T6 not recommended No interference with airway Avoids bronchospasm No swings in intrathoracic pressure No danger of pneumothorax from N 2 O Sedation reqd. May compromise expiratory fn. Peripheral Nerve Blocks: Suitable for peripheral limb surgeries Minimal respiratory effects Supraclavicular techniques contraindicated in severe Pulmonary disease Slide 55 Concerns in RA Improved Surgical outcome: Better pain control Attenuation of neuroedocrine respones to surgery Improvement of tissue oxygenation Maintenance of immune function Fewer episodes of DVT, PE, stroke, blood Tx Technique of choice in perineal, pelvic extraperitoneal & lower extremities No benefit over GA in Intraperitoneal surgery, or when high levels are needed Slide 56 Concerns in GA Airway instrumentation & bronchospasm Residual NMB Nitrous Oxide Attenuation of HPV Respiratory depression with opioids, BZDs Airway humidification Slide 57 Premedication Sensitivity to the effect of respiratory depressants Opioids & Benzodiazepines - response to hypoxia, hypercarbia Bronchodilator puff / nebulisation, inhaled steroids Atropine ?: Should be individualised Decreases airway resistance Decreases secretion-induced airway reactivity Decreases bronchospasm from reflex vagal stimulation Cause drying of secretions, mucus plugging Slide 58 General Anaesthesia: Induction Opioids: Fentanyl(DoC) Morphine,Pethidine Respiratory Depression, Histamine release, Chest tightness Propofol (DoC) Better suppression of laryngeal reflexes Hemodynamic compromise Agent of choice in stable patient Ketamine Bronchodilator Catecholamine release, neural inhibition Tachycardia and HT, may increase PVR Slide 59 Intubation NMB : Succinyl Choline (1-2mg/kg) Vecuronium(0.08-0.10 mg/kg) Rocuronium (0.6-1.2 mg/kg ) Attenuation of Intubation Response: IV lignocaine (1- 1.5 mg/kg) 90s prior to laryngoscopy Fentanyl 1-5 microgram/Kg Esmolol 100-150mg bolus Adequate plane of anaesthesia prior to intubation LMA Vs Endotracheal Tube Avoids tracheal stimulation P-LMA also allows for suctioning Slide 60 Maintenance Muscle relaxant Prefer Vecuronium, Rocuronium, Cisatracurium Avoid Atracurium, Mivacurium, Doxacurium ( histamine release) Volatile anaesthetic NO Caution in pulmonary bullae, dilution of delivered O 2 Inhalational agents attenuate HPV Sevoflurane: non pungent, bronchodilator Halothane: Non pungent, bronchodilator. Slower onset & elimination, Sensitises to catecholamines Slide 61 Maintenance Ventialatory Strategy: Aim: Maximise alveolar gas emptying Minismise dynamic hyperinflation, iPEEP Settings: Decrease minute vent Low frequency Adequate Exp time, Low I:E ratio, minimal exp pause Reduce exp flow resistance Recruitment maneuvers Acceptance of mild hypercapnia & acidemia Humidification of gases Pressure Cycled mode with decelerating flow. Slide 62 Maintenance Monitoring ECG, NIBP Pulse Oximetry Capnography Neuromuscular Monitoring Depth of Anaesthesia Intraoperative IV Fluids Excessive IV volume Water accumulation & tissue edema Respiratory/heart failure Haemodynamic goal directed fluid loading Restrictive fluid administration Slide 63 Intraoperative Increased PIP Bronchospasm Light anaesthesia, coughing, bucking Obstruction in the circuit Blocked / kinked tube Endobronchial intubation Pneumothorax Pulmonary embolism Major Atelectasis Pulmonary edema Aspiration pneumonia Head down position, bowel packing Slide 64 Management of intraoperative bronchospasm Increase FiO2 Deepen anaesthesia Commonest cause is surgical stimulation under light anaesthesia Incremental dose of Ketamine or Propofol Relieve mechanical stimulation endotracheal suction Stop surgery 2 agonists Nebulisation or MDI s/c Terbutaline, iv Adrenaline intravenous Aminophyline Intravenous corticosteroid indicated if severe bronchospasm Slide 65 Reversal/ Recovery: Neostigmine - may provoke bronchospasm Atropine 1.2-1.8mg or Glycopyrrolate 0.6mg before Neostigmine Tracheal toileting Extubation : deep or awake? Deep extubation may reduce chance of bronchospasm Deep Difficult airway Difficult intubation Residual NMB Full stomach Good airway - accessible Easy intubation No Residual NMB Normothermic Not at increased risk of aspiration NOYES Slide 66 Post operative care Risk of Post op pulmonary complications Postoperative analgesia Parenteral NSAIDS Neuraxial drugs Nerve blocks PCA Postoperative respiratory therapy Chest physiotherapy & postural drainage Voluntary Deep Breathing Incentive Spirometry Slide 67 Post operative care Mechanical Ventilation: Indications: Severe COPD undergoing major surgery FEV 1 /FVC 50mm Hg FiO 2 & Ventillator settings adjusted to maintain PaO 2 60-100 mm Hg & PaCO 2 in range that maintains pH at7.35-7.45 Continue Bronchodilators Oxygen therapy Lung Expansion maneuvers Slide 68 Post Operative Pulmonary Complications: Incidence: 6.8% (Range 2-19%) (Sementa et al, Annals of internal Medicine, 2006,144:58195) Include: Atelectasis Bronchopneumonia Hypoxemia Respiratory Failure Bronchopleural fistula Pleural effusion Slide 69 Post Operative Pulmonary Complications: Predictors of PPCs: Patient Related: Age > 70 yrs ASA Class II or above CHF Pre-existing Pulmonary Disease Functionally Dependent Cigarette smoking Hypoalbuimnemia, 3.5g/dL Procedure Related: Emergency Surgery Duration > 3 Hrs GA Abd, Thoracic, Head & Neck, Nuero, Vascular Surgery Slide 70 Post Operative Pulmonary Complications: Specific Risk Factors: COPD Bronchial Asthma GA OSA Advanced age Morbid Obesity(BMI > 40) Functional limitation Smoking > 20 Pack year Alcohol consumption (>60ml ethanol/day) Slide 71 Post Operative Pulmonary Complications: Risk Reduction Strategies: Preoperative: Smoking cessation Bronchodilatation Control infections Patient Education Intraoperative: Minimally invasive surgery Regional Anaesthesia Duration < 3 Hrs Post operative: Lung Volume Expansion Maneuvers Adequate Analgesia Slide 72 Post Operative Pulmonary Complications: Post Operative Analgesia: Opioids Paravertebral/Intercostal N Blocks Epidural Analgesia LA Opioids NSAIDS Bronchospasm Slide 73 Post Operative Pulmonary Complications: Lung Expansion maneuvers: Incentive spirometry Deep breathing exercises Chest Physiotherapy & postural drainage Intermittant Positive Pressure Ventilation CPAP, BiPAP Early Ambulation Slide 74 Summary: COPD is a progressive disease with increasing irreversible airway obstruction. Cigarette smoking is the most important causative factor for COPD Smoking cessation & LTOT are the only measures capable of altering the natural history of COPD. COPD is not a contraindication for any particular anaesthsia technique if patients have been appropriately stabilised. COPD patients are prone to develop intraoperative and postoperative pulmonary complications. Preoperative optimisation should include control of infection and wheezing. Postoperative lung expansion maneuvers and adequate post op analgesia have been proven to decrease incidence of post op complications. Slide 75 References: Stoeltings Anaesthesia & Coexisting Disease, 5 th Ed. Standards for Diagnosis & Management of COPD Patients, American Thoracic Society & European Respiratory Society Global Initiative for COPD Refresher course lectures, 57 th National Conference of ISA COPD: Perioperative management, M.E.J. Anesth 2008 19(6) Post Operative Pulmonary Complications, IJA April 2006 Periop Management of patients with COPD: Review, IJ COPD 2007:2(4) 493:515 Harrisons Principles of Medicine, 16 th Ed Principles of respiratory Care, Egans, 9 th Ed Millers Anaesthsia, 7 th Ed Irwin & Rippes Intensive care medicine, 6 th Ed. Clinical Application of Mechanical Ventilation, David W Chang, 3 rd Ed Slide 76