Clinical Approach to Chronic Respiratory Insufficiency - Lecture Notes

Clinical Approach to Chronic Respiratory Insufficiency

Trigger 1: Lance Aitken's Case

• Lance Aitken, a 57-year-old male, consults his GP for the first time in several years.
• He reports experiencing shortness of breath, which has worsened to the point where he couldn't finish a golf game.
• He mentions reducing physical activities due to breathlessness.
• He and Michael haven't been walking to the racetrack due to financial constraints.

Trigger 2: Smoking History

• Lance has been a heavy smoker since the age of 17.

History of Presenting Complaint (HPC)

• Description of Shortness of Breath:
  • Lance describes it as feeling "hungry for more air" and unable to get enough air.
  • The onset was gradual, worsening steadily over time.
  • Exacerbated by physical activity.
  • Asthma puffers (belonging to Michael) provide no relief.
• Other Symptoms:
  • Persistent fatigue.
  • Recent cough lasting several months, exceeding his usual "smoker's cough."
  • Mostly non-productive cough, occasionally brings up clear phlegm with streaks of blood.
• Smoking History Details:
  • Difficulty quitting smoking.
  • Longest abstinence was 2 months, 5 years ago.
  • Started smoking 'roll your owns' at age 17 (40 years).
  • Smoked approximately 25 cigarettes per day, reducing consumption slightly recently due to breathlessness.
• Negative Symptoms:
  • Denies chest pain, discomfort, or tightness.
  • Denies wheeze, hoarseness, headache, or swelling of the arms, shoulders, or face.
  • Denies fevers, shakes, weight loss, or night sweats.
  • Not worsened by lying down, denies ankle swelling, denies paroxysmal nocturnal dyspnoea.
  • Denies bony pain, anorexia, nausea, and constipation.
  • Denies past asbestos or silica exposure.
  • Does not keep pet birds.

Past Medical and Surgical History

• No past hospitalizations or surgeries.
• No chronic conditions, but experiences significant symptoms with colds/flu.

Medications

• Nil.

Allergies

• Nil known drug allergies (NKDA).

Family History

• Mother died at 64 with pancreatic cancer.
• Father died at 78 from complications of diabetes (kidney disease).
• One brother in good health.

Social and Lifestyle History

• Drinks 2-3 schooners most nights.
• Worked as a driver in various mines, recently started at Cadia-Ridgeway copper mine.
• Lives with partner of 30 years, Michael.
• No children, but brother’s grandchildren visit often.
• Michael has worked sporadically as a diesel mechanic but has had difficulty maintaining regular employment due to depression.

Examination Findings

• Mild increased work of breathing at rest.
• Vitals:
  • BP: 115/71
  • PR: 96, regular
  • RR: 20
  • SpO2: 86% on room air (RA)
  • Temperature: 37°C
• Respiratory:
  • No wrist tenderness.
  • Mild clubbing present in hands.
  • Equal percussion note bilaterally.
  • Expiratory wheeze.
  • Nil crackles.
• Cardiovascular:
  • Strong radial pulse.
  • Jugular venous pressure not raised.
  • Heart sounds dual, no murmurs.
  • No peripheral oedema.

Clubbing of the Fingers

• Normal Finger: The length of the perpendicular dropped from point A to point B should be greater than a similar line from C to D. The angle described by A-C-E is usually <180 degrees.
• Clubbing: The distance C-D is greater than the distance A-B. The angle described by A-C-E is >180 degrees.

Investigations

• CXR (Chest X-Ray) and lung function testing were ordered.

Lung Function Test Results

• Report Summary:
  • Very severe obstructive ventilatory defect.
  • Significant bronchodilator response observed.
  • Severely reduced carbon monoxide transfer factor, indicating lung parenchymal and/or pulmonary vascular dysfunction.
  • Increased plethysmographic lung volumes.
  • Increased RV/TLC ratio indicating hyperinflation and gas trapping.
  • Arterial blood gas analysis on room air reveals alveolar hypoventilation and hypoxaemia with metabolic compensation.
• Impression: Severe COPD

Chest X-Ray Findings

• Large rounded opacity projecting over the right upper lobe, requiring CT assessment for further characterization.
• Heart and mediastinum: Normal.
• Bones: Normal.
• Review areas: All normal.

CT Scan Report

• A CT with contrast is performed to further characterize the mass.
• Solid mass in the right upper lobe, abutting the mediastinum, with spiculated margins.
• No consolidation to suggest infection.
• Most likely represents a malignancy.
• Background emphysematous changes noted, consistent with a smoking history.

CT PET Scan Report

• Increased metabolic activity in the mass.
• No evidence of lymphadenopathy or metastases.

Follow-up and Diagnosis

• Pathology determines the tumor to be a non-small cell lung cancer: squamous cell.
• TNM Stage II A/B due to size.
• Referred to the lung cancer multidisciplinary team (MDT).
• Referred to a cardiothoracic surgeon for lobectomy with anaesthetic pre-operative assessment, given poor lung function.
• Continued follow-up through his GP and the lung MDT.

Cigarette Smoking

• Risk Factor: Most important risk factor in lung cancer and COPD.
• Causation: Causes 90% of male and 65% of female lung cancers.
• Airway Disease: 50% of smokers develop some airway disease; 15-20% become disabled.
• Cessation Benefits:
  • Early cessation can stop accelerated loss of lung function.
  • Later cessation may be less effective due to persistent airway inflammation.
  • Cessation at any age reduces overall mortality.

Smoking Cessation and Tobacco Control

• Statistics:
  • 70% of smokers want to quit.
  • 46% try to quit each year.
• Quit Rates:
  • Spontaneous quit rates: approximately 1% per year.
  • Simple physician advice: increases quit rates to 3%.
  • Minimal intervention programs: increase quit rates to 5-10%.
  • Intensive treatments (cessation clinics): increase quit rates to 25-30%.

5-A Strategy for Smoking Cessation

• Ask: Identify smokers; Document.
• Assess: Degree of nicotine dependence and motivation/readiness to quit.
• Advise: Smokers about the risks of smoking and benefits of quitting.
• Assist: Cessation including pharmacological interventions and referral to Quitline, etc.
• Arrange: Follow-up to reinforce message.

Benefits of Quitting Smoking

• Substantial benefits for smokers of any age.
• Quitting before 50 years: Halves the risk of dying in the next 15 years compared to continuing smokers.
• Lung Cancer Risk:
  • After 10 years of cessation: Reduces to ½ that of a smoker.
  • After 15 years of cessation: Reduces to 1/6 that of a smoker.
• Mortality Reduction: 50% reduction when quitting at 55 years versus quitting at 75 years.
• Myocardial Infarction Risk: Decreases to non-smoker levels within 1 year of quitting.
• FEV1 Decline: Rate slows and returns to close to that of non-smokers.

Chronic Obstructive Pulmonary Disease (COPD)

• Definition: Heterogeneous collection of conditions characterized by persistent expiratory airflow limitation.
• FEV1/FVC < 70% is the ratio that indicates airflow limitation.
• Aetiologies:
  • Cigarette smoke (most important).
  • Occupational exposure.
  • Asthma.
  • Cystic Fibrosis (CF) and other bronchiectasis.

GOLD Definition of COPD

• "COPD is a disease state characterised by airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the lungs to noxious particles and gases."

Emphysema

• Definition: Condition of the lung characterized by abnormal permanent enlargement of the air spaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis.

Chronic Bronchitis

• Definition: Chronic productive cough present for 3 months or more for 2 successive years.

Pulmonary Function Tests

• Lung Volumes and Capacities
  Volumes:

  • IRV: Inspiratory reserve volume
  • VT: Tidal volume
  • ERV: Expiratory reserve volume
  • RV: Residual volume
    Capacities:
  • IC: Inspiratory capacity
  • FRC: Functional residual capacity
  • TLC: Total lung capacity
  • VC: Vital capacity

• TLC, RV, and their ratio provide the most information about restrictive lung disease and help differentiate between restrictive and obstructive disorders.

• However, TLC and RV are effort-dependent, so an evaluation of strength and/or effort is needed.

• In contrast, the FRC is effort-independent.

Airflow Limitation in COPD

• Description: Airway limitation describes the pathophysiology of ‘obstructive lung function’ in COPD.
• Airways in COPD are narrowed due to airway inflammation but not as severe asthma.
• Airways are not held open due to reduction in traction by loss of recoil or elasticity of lung parenchyma.
• Equal Pressure Point Theory.

Pulmonary Function Tests (PFTs)

• Types of Tests:
  • Spirometry
  • Lung Volumes
  • Volume-Pressure Relations
  • CO Diffusing Capacity
  • Arterial Blood Gases
  • Maximum inspiratory and expiratory muscle pressures

Spirometry in COPD

• Importance: Most important test for diagnosing and assessing severity of COPD.
• Diagnosis: Post-bronchodilator FEV1/FVC ratio <0.7.
• Severity: FEV1 most important: <80% predicted.
• Significant increase in FEV1 with Bronchodilator suggests asthma factor: >12% and 200ml.

Severity of COPD (COPDX)

• Mild: FEV1 60-80% predicted, few symptoms, breathless on moderate exertion, little effect on daily activities.
• Moderate: FEV1 40-59% predicted, cough and sputum production, breathless walking on level ground, increasing limitation of daily activities, recurrent chest infections.
• Severe: FEV1 <40% predicted, breathless on minimal exertion, daily activities severely curtailed, exacerbations of increasing frequency and severity.
• Frequency of exacerbations may increase with severity.
• Comorbid conditions present across all severity groups.

Measuring Breathlessness

• Modified Medical Research Council (MRC) Dyspnoea Scale:
  • Grade 0: "I only get breathless with strenuous exercise"
  • Grade 1: "I get short of breath when hurrying on the level or walking up a slight hill"
  • Grade 2: "I walk slower than people of the same age on the level because of breathlessness or have to stop for breath when walking at my own pace on the level"
  • Grade 3: "I stop for breath after walking about 100 yards or after a few minutes on the level"
  • Grade 4: "I am too breathless to leave the house" or "I am breathless when dressing"

Mechanisms of Dyspnoea

• Efferent Signals: From the motor cortex to ventilatory muscles.
• Afferent Signals:
  • Sensory cortex (effort, air hunger, chest tightness).
  • Chemoreceptors.
  • Brain stem.
  • Upper airway.
  • Chest wall.

Respiratory Failure

• Definition: Impairment of the function of the respiratory system that causes either severe dysfunction in other organs or threatens life.
• Affects either: Gas exchange function of the lung and Ventilatory pump
  • Hypoxemia: PaO2 < 60 mmHg
  • Hypercapnia: PaCO2 > 45 mmHg
  • Respiratory acidosis: pH < 7.35

Acute Respiratory Failure

• Causes:
  • Airways: Upper airway obstruction, Asthma, Acute COPD.
  • Parenchymal: Pneumonia, Pulmonary edema, Toxins, Inflammation, Bleeding.
  • CNS, nerves and muscles

Chronic Respiratory Failure

• Causes:
  • COPD
  • Restrictive lung disease
  • Chest wall deformity
  • Respiratory muscle disease

Cyanosis

• Definition: Blue color due to the presence of 3-5 g/100ml blood of non-oxygenated haemoglobin.
• Central Cyanosis: Refers to reduction in oxygenation of arterial blood i.e., hypoxaemia – seen best in the warm mucosa of the mouth.
• Peripheral Cyanosis: Refers to reduction in capillary and venous blood oxygen due to low flow rates, e.g., poor cardiac output or skin vessel shutdown due to cold temperature – seen in periphery, e.g., fingers, but also lips.

Therapeutic Goals: COPDX

• C: Case finding and confirm diagnosis
• O: Optimise Function
• P: Prevent deterioration
• D: Develop a plan of care
• X: Manage eXacerbations

COPDX: C - Case Finding and Confirm Diagnosis

• What risk factors contribute to COPD?
• What is the first step in the diagnosis of COPD?
• How is COPD confirmed?
• Is it COPD or asthma?
• Is it COPD or another condition?
• How is severity of COPD confirmed?

COPDX: O - Optimise Function

• Optimising function: Where to start?
• What non-pharmacological strategies are recommended?
• What is the recommended approach to prescribing pharmacological therapies?
• When should inhaler technique and adherence be reviewed?
• How should treatment of comorbidities be optimised?
• When should referral to specialist respiratory services be made?

COPDX: P - Prevent Deterioration

• Why give smoking cessation advice?
• How can exacerbation risk be reduced?
• Why immunise against influenza and pneumococcal infection?
• Should mucolytics be used?
• Who benefits from long-term oxygen therapy?

COPDX: D - Develop a Plan of Care

• What is good chronic disease care and what are the benefits?
• How can health professionals improve quality of life and reduce disability?
• What is self-management support and how can patients benefit?
• What other services can benefit patients?
• When and how should palliative care be considered?

COPDX: X - Manage Exacerbations

• How is a COPD exacerbation defined?
• What are the benefits of early diagnosis and treatment of exacerbations?
• When should a patient with COPD be hospitalised?
• Can patients with an exacerbation be treated at home?
• Are inhaled bronchodilators effective for treatment of exacerbations?
• Are oral corticosteroids effective for treating exacerbations?
• When are antibiotics beneficial in treating a patient with an exacerbation?
• Is oxygen beneficial in treating a patient with an exacerbation?
• When is non-invasive ventilation (NIV) effective?
• Following an exacerbation, how soon can pulmonary rehabilitation be commenced?
• What is the best approach to post-hospital care after an exacerbation?

Oxygen Therapy

• Long-term therapy in management of severe COPD
• Extends life in hypoxemic COPD patients
• 24hr regimen more beneficial than 12hr regimen

Benefits of Long-Term Oxygen Therapy

• Reduction in mortality
• Reduction in Hb/haematocrit
• Modest neuropsychological improvement
• Some improvement in pulmonary haemodynamics
• Dramatic improvement in pulmonary hypertension and RHF (Cor Pulmonale)
• May diminish dyspnea and increase exercise capacity

Indications for Oxygen Therapy

• Patients with resting arterial PO2 of 55mm Hg or less while breathing air
• Patients with resting arterial PO2 of between 56 and 59 mm Hg if Polycythaemia ( Hb > 170 or haematocrit ³ 55%) or evidence of Cor Pulmonale
• Patients with arterial PO2 of 60mm Hg or higher who develop worsening hypoxemia with exercise and improve walk distance with oxygen
• Nocturnal hypoxaemia: SpO2 < 90% for 30% night