Week 7: COPD Flashcards
What things decrease oxygen affinity for hemoglobin (shift curve right) ?
Low pH
High blood CO2
High temperature
Added BPG
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
What is respiratory Center
Medulla oblongata and pons
What does pons regulate ?
Rate of breathing
What muscles are used for expiration during active ventilation ?
Internal intercostal muscles
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
Pontine respiratory Center function
Modify rate and pattern of respiration
Apneustic centre
Sends stimulatory discharge to inspiratory neurons promoting inspiration
Removal of its effects—> shallow, irregular respiration
Pneumotaxic centre function
Regulation of respiratory volume and rate
Controlling cessation of inspiratory RAMP signal from DRG
Switch off DRG and Apneustic centre —> expiration
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
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
Peripheral chemoreceptors
In direct contact with arterial blood
Afferent neurons project to medullary respiratory control areas
Respond mostly to changes in PAO2 or pH
what is the most common cause of massive hemoptysis ?
Something wrong with bronchial circulation
Important history for hemoptysis diagnosis
TB or lung disease Environmental or TB exposures Smoking Travel Immune status Toxins and drug use
Important laboratory data for patients presenting with hemoptysis
HCT/platelets Renal function and urinalysis Coagulation factors ABG Type and cross Sputum
Advantages of rigid bronchoscopy
Secure airway
Large port: greater suction
Greater visualization than flexible
Endobronchial tamponade vs selective intubation
ET: inflated tracheal cuff and inflated bronchial cuff in bad lung
SI: inflated bronchial cuff in good lung
Topical therapy examples for hemoptysis
Cold saline irrigation —> vasoconstriction
Vasoconstrictive agent: epinephrine
Topical coagulants: fibrinogen, thrombin
4 common chronic obstructive diseases:
Asthma
COPD
Bronchiectasis
Bronchiolitis
What airways are involved with asthma ?
Secondary bronchus - respiratory bronchiole
What airways are involved with COPD ?
Bronchioles - respiratory bronchioles
4 common symptoms of chronic obstructive airway diseases
Cough
Sputum
Wheeze
Dyspnea
Sources of mucus
Goblet cells
Bronchial mucus glands
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
