9.-anaesthesia-for-copd.pptx
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Anaesthesia for COPD
Anaesthesia for Patients with COPD
Dr Sajith Damodaran
University College of Medical Sciences & GTB Hospital, Delhi
COPD: Pathophysiology, Diagnosis, Treatment
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.
In patients with COPD either of these conditions may be present but the relative contribution of each is different.
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.
In patients with COPD either of these conditions may be present but the relative contribution of each is different.
4
COPD:
Includes:
Chronic Bronchitis
Emphysema
Peripheral Airways disease
Doesnt include
Asthma, Asthmatic Bronchitis
Cystic Fibrosis
Bronchiactesis
Pulmonary fibrosis due to other
causes
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
6
Comparative features of COPD
FeatureChronic BronchitisEmpysemaMech of Airway ObstructionDecreased Lumen d/t mucus & inflammationLoss of elastic recoilDysnoeaModerateSevereFEV1 DecreasedDecreasedPaO2 Marked Decrease (Blue Bloater)Modest Decrease (Pink Puffer)PaCO2 IncreasedNormal or DecreasedDiffusing capacityNormalDecreasedHematocritIncreasedNormalCor PulmonaleMarkedMildPrognosisPoorGoodCOPD: 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
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.)
It is increasingly apparent that COPD often has its roots decades before the onset of symptoms
[14]. Impaired growth of lung function during childhood and adolescence, caused by recurrent
infections or tobacco smoking, may lead to lower maximally attained lung function in early
adulthood [16]. This abnormal growth will, often combined with a shortened plateau phase in
teenage smokers, increase the risk of COPD. This is visualised in figure 1 [17].
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Pathophysiology:
Pathological changes are seen in 4 major compartments of lungs:
central airways
Peripheral airways
lung parenchyma
pulmonary vasculature.
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
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
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
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
Infectious process [7, 8]: viral (Rhinovirus spp., influenza); bacteria (Haemophilus influenzae,
Streptococcus pneumoniae, Moraxella catarrhalis, Enterobacteriaceae spp., Pseudomonas
spp.).
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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.
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
Treatment
Supplemental Oxygen (if SPO2 < 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
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
. Preparation for Anaesthesia
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 CO2 retention
Age Related Pulmonary Changes:
Pathological changesEffectImplicationsDecreased efficiency of lung parenchymaDecreased VCIncreased RVRespiratory FailureDecreased Muscle strengthDecreased Compliance, FEV1 Poor coughInfectionAlveolar septal destructionDecreased alveolar areaDecreased gas exchangeBrohchiolar damageIncreased closing volumeAir trappingDecreased PaO2 Dilated upper airwaysIncreased VD Decreased gas exchangeDecreased reactivityDecreased laryngeal reflexesDecreased vent response to hypoxia, hypercarbiaIncreased AspirationIncreased resp. failureAnaesthetic 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
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 & CO2
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
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
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
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 P2
Right Parasternal heave
Tricuspid regurgitation
Pre-operative assessment: Examination
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
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
Pulmonary Function Tests:
MeasurementNormalObstructiveRestrictiveFVC (L) 80% of TLC (4800) FEV1 (L) 80% of FVC FEV1/FVC(%) 75- 85%N to N to FEV25%-75%(L/sec)4-5 L/ secN to PEF(L/sec)450- 700 L/minN to Slope of FV curveMVV(L/min)160-180 L/minN to TLC6000 mlN to RV1500 mLRV/TLC(%)0.25NFEV1
FEV1
FVC
seconds
2
1
3
4
5
0
1
2
3
4
Litres
5
COPD
NORMAL
60%
3900
2350
COPD
80%
5200
4150
Normal
FEV1/FVC
FVC
FEV1
FVC
Spirometric tracing in COPD patients
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Maximum inspiratory and expiratory flow-volume curves (i.e., flow-volume loops) in four types of airwayobstruction.
Preoperative Assessment: Investigations
ECG
Signs of RVH:
RAD
p Pulmonale in Lead II
Predominant R wave in V1-3
RS pattern in precordial leads
Arterial Blood Gases:
In moderate-severe disease
Nocturnal sample in cor Pulmonale
Increased PaCO2 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
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
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
Smoking cessation and time course of beneficial Effects
Time after smokingPhysiological Effects12-24 HrsFall in CO & Nicotine levels48-72 HrsCOHb levels normaliseAirway function improves1-2 WeeksDecreased sputum production4-6 WeeksPFTs improve6-8 WeeksNormalisation of Immune function8-12 WeeksDecreased overall post operative morbidityDilatation of Airways:
Bronchodilators:
Only small increase in FEV1
Alleviate symptoms by decreasing hyperinflation & dyspnoea
Improve exercise tolerance
Anticholinergics
Beta Agonists
Methylxanthines
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
Better in COPD then asthma
S/E Dryness of mouth, Scratching of trachea, Cough, nervousness
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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
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.
Inhaled Corticosteroids:
Anti-inflammatory
Restore responsiveness to 2 agonist
Reduce severity and frequency of exacerbations
Do not alter rate of decline of FEV1
Beclomethasone, Budesonide, Fluticasone
Dose: 200 g BD upto 400 g QID
> 1600 g / day- suppression of HPA axis
Not bronchodilators.
bronchial reactivity and edema
inflammatory response
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. AnaestheTIC Technique
Anaesthetic Technique
COPD is not a limitation on the choice of anaesthesia.
Type of Anaesthesia doesnt predictably influence Post op pulmonary complications.
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 N2O
Sedation reqd. May compromise expiratory fn.
Peripheral Nerve Blocks:
Suitable for peripheral limb surgeries
Minimal respiratory effects
Supraclavicular techniques contraindicated in severe
Pulmonary disease
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
Concerns in GA
Airway instrumentation & bronchospasm
Residual NMB
Nitrous Oxide
Attenuation of HPV
Respiratory depression with opioids, BZDs
Airway humidification
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
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
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
Maintenance
Muscle relaxant
Prefer Vecuronium, Rocuronium, Cisatracurium
Avoid Atracurium, Mivacurium, Doxacurium ( histamine release)
Volatile anaesthetic
NO Caution in pulmonary bullae, dilution of delivered O2
Inhalational agents attenuate HPV
Sevoflurane: non pungent, bronchodilator
Halothane: Non pungent, bronchodilator.
Slower onset & elimination, Sensitises to catecholamines
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.
Reduce exp low res by bronchodilators, coriticosteroids, low res tubings, heliox
The pressure ventilatory mode (PV) with a decelerating flow has the potential advantage of decreasing the peak airway pressure and providing more homogenous distribution of inspiratory airflow at a lower or similar mean distending pressure
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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
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
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
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
NO
YES
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
Post operative care
Mechanical Ventilation:
Indications:
Severe COPD undergoing major surgery
FEV1/FVC 50mm Hg
FiO2 & Ventillator settings adjusted to maintain PaO2 60-100 mm Hg & PaCO2 in range that maintains pH at7.35-7.45
Continue Bronchodilators
Oxygen therapy
Lung Expansion maneuvers
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
Grade I complication entails any deviation from the normal postoperative course with no need for medical interventions, except antiemetics, antipyretics, analgesics, electrolytes, diuretics. Grades II and III involve complications requiring pharmacological treatment, blood transfusions or endoscopic, surgical or radiological interventions. Grade IV includes lifethreatening complications as well as single or multiple organ failure requiring ICU admission. Ultimately, perioperative death corresponds to a grade V.
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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
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)
he incidence of PPCs (except atelectasis) most often parallels the severity of respiratory impairment (moderate,if FEV1 50%80%; severe, if FEV1 50%), particularly in patients with abnormal clinical findings (decreased breath sounds, wheezes, ronchi, prolonged expiration) and/or marked alterations of gas exchange (PaCO2 7 kPa, hypoxemia requiring supplemental oxygen).
Br Asthma; Recent asthma symptoms, current use of anti-asthma drugs and history of tracheal intubation for asthma have all been associated with the development of PPCs.
70
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
Post Operative Pulmonary Complications:
Post Operative Analgesia:
Opioids
Paravertebral/Intercostal N Blocks
Epidural Analgesia
LA
Opioids
NSAIDS Bronchospasm
Post Operative Pulmonary Complications:
Lung Expansion maneuvers:
Incentive spirometry
Deep breathing exercises
Chest Physiotherapy & postural drainage
Intermittant Positive Pressure Ventilation
CPAP, BiPAP
Early Ambulation
Of proven benefit in decreasing PPCs. Decrease atelectasis by increasing lung volume All are equally efficacios
Incentive spirometry: Simple. Inexpensive. Objective goal given to the patient provides sustained lung expansion & helps in opening closed alveoli. But needs patient coorperation.
Positive pressure breathing tech not cost effective.
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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.
References:
Stoeltings Anaesthesia & Coexisting Disease, 5th Ed.
Standards for Diagnosis & Management of COPD Patients, American Thoracic Society & European Respiratory Society
Global Initiative for COPD
Refresher course lectures, 57th 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, 16th Ed
Principles of respiratory Care, Egans, 9th Ed
Millers Anaesthsia, 7th Ed
Irwin & Rippes Intensive care medicine, 6th Ed.
Clinical Application of Mechanical Ventilation, David W Chang, 3rd Ed