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 PulmonaleMarkedMildPrognosisPoorGood

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

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. failure

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

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(%)0.25N

FEV1

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 morbidity

Dilatation 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.

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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