Week 7: COPD Flashcards by Natasha Singer

What things decrease oxygen affinity for hemoglobin (shift curve right) ?

Low pH
High blood CO2
High temperature
Added BPG

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3 distinct components of neural control of breathing

Factors that:

Generate alternating inspiration/expiration rhythm
Help regulate the magnitude of ventilation
Modify respiratory activity for other purposes

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What is respiratory Center

Medulla oblongata and pons

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What does pons regulate ?

Rate of breathing

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What muscles are used for expiration during active ventilation ?

Internal intercostal muscles

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Dorsal respiratory group (DRG) function

inspiratory neurons that discharge during inspiration and stop discharging during expiration
generate RAMP signal
initiate inspiration with weak burst of APs that gradually increase in frequency then cease for next 3 seconds until new cycle
—> gradual increase in lung volume during inspiration

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Pontine respiratory Center function

Modify rate and pattern of respiration

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Apneustic centre

Sends stimulatory discharge to inspiratory neurons promoting inspiration
Removal of its effects—> shallow, irregular respiration

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Pneumotaxic centre function

Regulation of respiratory volume and rate
Controlling cessation of inspiratory RAMP signal from DRG
Switch off DRG and Apneustic centre —> expiration

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Central chemoreceptors pathway

Lying just beneath ventral surface of medulla
Relay most important sensory input about changes in their close environment to respiratory center in pons and medulla
- sensitive to change in PACO2

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How are central chemoreceptors stimulated by an increase in arterial PCO2 ?

CO2 crosses blood brain barrier
—> CO2 + H2O —> H2CO3–> HCO3- + H+
And H+ stimulate central chemoreceptors

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Peripheral chemoreceptors

In direct contact with arterial blood
Afferent neurons project to medullary respiratory control areas
Respond mostly to changes in PAO2 or pH

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what is the most common cause of massive hemoptysis ?

Something wrong with bronchial circulation

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Important history for hemoptysis diagnosis

TB or lung disease 
Environmental or TB exposures 
Smoking 
Travel 
Immune status 
Toxins and drug use

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Important laboratory data for patients presenting with hemoptysis

HCT/platelets 
Renal function and urinalysis 
Coagulation factors 
ABG 
Type and cross
Sputum

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Advantages of rigid bronchoscopy

Secure airway
Large port: greater suction
Greater visualization than flexible

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Endobronchial tamponade vs selective intubation

ET: inflated tracheal cuff and inflated bronchial cuff in bad lung
SI: inflated bronchial cuff in good lung

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Topical therapy examples for hemoptysis

Cold saline irrigation —> vasoconstriction
Vasoconstrictive agent: epinephrine
Topical coagulants: fibrinogen, thrombin

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4 common chronic obstructive diseases:

Asthma
COPD
Bronchiectasis
Bronchiolitis

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What airways are involved with asthma ?

Secondary bronchus - respiratory bronchiole

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What airways are involved with COPD ?

Bronchioles - respiratory bronchioles

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4 common symptoms of chronic obstructive airway diseases

Cough
Sputum
Wheeze
Dyspnea

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Sources of mucus

Goblet cells

Bronchial mucus glands

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Causes of dyspnea in obstructive lung diseases

Increased work of breathing due to increased airway resistance
Hypoxemia
Hyperinflation

Mechanisms of increased resistance

``` Smooth muscle contraction Wall thickening Luminal occlusion Decreased lung elasticity Obliteration ```

Primary mechanisms of increased resistance in asthma

Smooth muscle contraction Wall thickening Luminal occlusion

Primary mechanisms of increased resistance in COPD

Decreased lung elasticity | Obliteration

Inflammatory trigger in bronchiectasis

Bacteria

Bronchiectasis definition

Irreversible dilation of the bronchial tree - obliteration of peripheral small airways - repetitive of persistent infection of proximal airways

Bronchiectasis etiologies

``` CF Ciliary dysfunction syndromes Foreign bodies Tracheomalacia Relapsing polychrondritis Infective ```

What spirometry measure is decreased in asthma and COPD

FEV1: rate of lung emptying

What measure detects airway obstruction ?

Maximal expiratory flow (MEF)

Characteristics of squamous cell carcinoma

Central Often cavitate Keratin formation and intercellular bridges

Characteristics of adenocarcinoma

Mostly peripheral Commonest type in non-smokers Gland formation and/or mucin production

Characteristics of small cell carcinoma

Mostly central Highly malignant and often disseminated at time of presentation Cells with small oval hyperchromatic nuclei and scanty cytoplasm Tumour cells exhibit neuroendocrine differentiation

Characteristics of large cell carcinoma

Often peripheral | Composed of large polygonal cells with vesicular nuclei and often prominent nucleoli

What mutation testing is done with adenocarcinoma

EGFR and ALK

3 ways that lung cancer can spread

Locally Lymphatically Hematogenously

Treatments for relieving dyspnea in COPD patients

Oxygen Pulmonary rehabilitation Smoking cessation Short acting opioids

MPOWER

Monitor epidemic in your country Protect your population from 2nd hand smoke Offer treatment for those who want to quit smoking Warn, labels on tobacco products Enforcement on advertising bans Raise taxes

Mechanism of action of nicotine in CNS

Nicotine binds preferentially to nACh receptors in CNS (primary is a4B2 nACh in VTA ) After nicotine binds a4B2 nACh receptor in VTA —> release of dopamine in nucleus accumbens (nAcc) —> reward

Drugs for smoking cessation

Bupropion SR | Varenicline

What happens to FEV1 and FVC in COPD and asthma

Asthma: decreased FEV1, normal FVC COPD: decreased FEV1 and FVC

Airway hyperresponsiveness

Allergen exposure —> smooth muscle contraction —> limited airflow to respiratory airways for gas exchange Inflammation, edema, and mucus further close off conducting airways

Mechanism of action of B2 adrenergic receptor

Removal of Ca2+ from the cell Uncoupling of actin-myosin filaments —> smooth muscle relaxation

Treatment for asthma

mild: SABAs Severe: LABAs + corticosteroid

Side effects of B2 agonists

Agitation Tremor Tachycardia

Common symptoms of COPD

``` Dyspnea Chest tightness Wheezing Sputum production Shortness of breath ```

Mechanism of muscarinic antagonists

Relax smooth muscle by blocking the muscarinic acetylcholine receptors

Treatment for COPD

B2 adrenergic receptor agonists SAMAs LAMAs

Corticosteroid mechanism

Binds GC receptor —> Trans-repression: prevents translocation of inflammatory transcription factors from cytosol to nucleus Trans-activation: up regulates anti-inflammatory mediators by binding to glucocorticoid response elements

Thoracentesis

Insert needle through chest wall into the pleural space and drain pleural fluid

2 layers of pleura

Visceral: covers lungs Parietal: lines inside of thoracic cavity

Histology of parietal pleura

Loose CT Blood vessels and lymphatic lacunae Thin layer of mesothelial cells

What happens when there is differences in hydrostatic and osmotic pressures between vessels and pleural space ?

Fluid builds up in pleural space

What causes increased fluid entry in pleural effusion ?

Increase in permeability Increase in micro vascular pressure Decreased pleural pressure Decreased plasma oncotic pressure

Work up of pleural effusions

Cell count and differential Bacterial culture, AFB sweat and atypical mycobacterial culture Mycoplasma PCR and strep pneumoniae PCR

Transudate LUCKI ME

``` Liver Urinothorax CHD Kidney Iatrogenic Myxedema Embolic ```