Week 8: Respiratory Flashcards
What respiratory structures make up the respiratory zone?
respiratory bronchioles, alveolar ducts, alveoli
What is another name for the respiratory zone?
lung parenchyma
What is the major role of the respiratory zone?
responsible for gas exchange
What do each variable of Fick’s Law of Diffusion represent?
D: Partial pressures and gas solubilities
A: surface area of the respiratory membrane
C: concentration gradient
X: Thickness of the respiratory membrane
What are examples of diseases that affect the variables of Fick’s law of diffusion?
X: Pulmonary fibrosis
A: Emphysema or atelectasis
DC: High altitude - decreased concentrations of O2 in inspired air
Where is the respiratory regulatory center located and what are the two organs involved?
Regulatory center located in the brainstem
Medulla sets the rhythm, pons modifies the rhythm
What is the primary and secondary signal for respiratory regulation?
Primary: CO2
Secondary: O2
Define the following breathing patterns: eupnea, tachypnea, dyspnea, apnea
Eupnea: normal quiet breathing
Tachypnea: increased respiratory rate
Dyspnea: subjective sensation of breathlessness
Apnea: cessation of respiration
What are Cheyne-Stokes respirations? What is it a sign of and when is it often seen?
waxing and waning tidal volume with periodic apnea sign of impending death, seen in heart failure and stroke
What are Kusmaal respirations and when does it occur?
rapid and deep ventilation - when body becomes acidic, respiratory compensation, example DKA
Define and explain the importance of pulmonary function testing and arterial blood gas evaluation with regard to pulmonary assessment.
PFT: tests elastic properties of the lung & airway resistance
ABG: assess pulmonary gas exchange and delivery to tissues
Define ventilation and perfusion
Ventilation: flow of gases into and out of the alveoli of the lungs
Perfusion: flow of blood in the adjacent pulmonary capillaries
How is ventilation and perfusion normally matched?
Normally matches cardiac output - 5-6 liters
Normal ratio: 0.6-3.0
What is the consequence of V/Q mismatching on gas exchange? What are the s/s (3)?
This will cause a change in the V/Q ratio and can affect the efficiency of gas exchange
Increasing inspired O2 fraction will improve hypoxia due to an inequality in V/Q but the greater the inequality the less the response to increasing FIO2
S/S: dyspnea, cyanosis and clubbing
Define hypoxemia and what is the common cause
Hypoxemia = PaO2 < 85mmHg
Common cause: mismatched ventilation and perfusion
What are causes of mismatched ventilation and perfusion (4)?
- Decreased O2 in inspired air: high altitude or anesthesia mismanagement
- Alveolar hypoventilation: pulmonary or neuromuscular disease, CNS depression, inadequate ventilation during anesthesia
- Diffusion abnormalities: pulmonary edema, fibrosis
- Issues with circulation: right to left shunt, congenital heart defect, atelectasis
Define hypercapnia and what is the common cause
Hypercapnia = increased PaCO2 (normal 38-42)
Common cause: hypoventilation
What are the causes of hypoventilation (5)?
- Depression of resp center
- Diseases of medulla (infections of CNS or trauma)
- Spinal cord disruption
- Diseases of the neuromuscular junction
- Large airway obstruction
Define dead space, what disorders can increase dead space?
Dead space: ventilation without perfusion due to occlusion of blood supply
Pulmonary embolism, emphysema
Define shunt and identify three causes of shunt
Shunt: no ventilation with perfusion; - no gas exchange occurs in that alveoli and increases shunt fraction
obstructed airway, bronchoconstriction, pulmonary edema
Define compliance
Compliance = measure of lung and chest wall dispensability, defined as volume change per unit of pressure change
How do elastin and collagen contribute to compliance?
Elastin: stretchy connective tissue fiber within alveolar walls that contributes to passive deflation of the lungs
Collagen: resistance to stretchability (opposes surface tension)
Define surface tension
Refers to tendency for liquid molecules exposed to air to adhere to one another
What is surfactant?
Surfactant: detergent-like substance that helps keep air stretches open, reduces air patches of liquid on sides of wall
What happens in a disorder of increased compliance, and what is an example?
Disorder of increased compliance: over stretched, recoil is affected
Emphysema - loss of elastic tissue
What happens in a disorder of decreased compliance, and what are two examples?
Disorder of decreased compliance: lungs become stiff
pulmonary fibrosis - increased collagen which enhances stiffness
pulmonary edema - increased interstitial fluid
Define pneumothorax
Pneumothorax = accumulation of air in the pleural space that can result in partial or complete collapse
Distinguish between spontaneous, secondary, tension pneumothorax
Spontaneous (closed): air-filled blebs/blisters on lung surface form and rupture, allowing air from the inside of the lungs to enter the pleural space; commonly occurs in male smokers
Secondary: air enters pleural space as a result of chest wall injury or punctures
Tension: air enters but does not leave pleural space
Define pleural effusion
Pleural effusion = abnormal collection of fluid in pleural cavity
Define hydrothorax, when is it seen and what is the possible cause?
Hydrothorax - transudate (filtrate of blood)
Seen in CHF, renal failure, nephrosis, liver failure
Poss cause: loss of albumin, changes osmotic pressure and leads to collection of fluids
Define empyema, when is it seen (4)?
○ Empyema - exudate that comes from inflammatory process or immune response
Seen in infections, malignancies, RA, lupus
Define hemothorax, when is it seen?
Hemothorax - blood
Seen in chest injury, surgery, malignancies, vessel rupture
Define chylothorax, what is the cause and when is it seen?
Chylothorax - chyle (lymph)
Caused by obstructed lymph return to blood
Seen in trauma, infection, malignant infiltration
Define atelectasis, what are causes of primary vs. secondary (3)?
Atelectasis = collapse of previously expanded lung tissue (secondary) or incomplete expansion of lungs at birth (primary)
Primary - typically due to insufficient surfactant
Secondary - typically due to airway obstruction, lung compression (pneumothorax or pleural effusion), increased lung recoil (decreased surfactant)
How does surgery increase the risk for atelectasis?
Anesthesia - nitrogen wash out
Narcotics
Immobility
Explain how decreased surfactant; ineffective cough reflex; and increased sputum viscosity contribute to atelectasis.
decreased surfactant: increased recoil
Ineffective cough reflex: poor alveolar expansion and obstruction
Increased sputum viscosity: airway obstruction
Define airway resistance; explain what law explains resistance; and, identify the one parameter that is most important for defining resistance to airflow
Airway resistance: resistance to airflow, defined by differences between atmospheric pressure and alveolar pressure relative to resistance
Law: Pouiseuille’s law
Parameter: radius of the airway
Fill in the blanks: The _____ the radius the _____ the resistance
- smaller
2. larger
Define obstructive disorder, identify the best indicator of obstructive lung disorder
Obstructive disorder: obstruct the ability of air to flow into the lungs, characterized by increased airway resistance
Best indicated by FEV1/FVC ratio (reduced)
Define chronic bronchitis
inflammation, mucus secretion, obstruction of airway
Define bronchiestasis
persistent abnormal dilation of the bronchi that is frequently associated with bronchitis
Define bronchiolitis
inflammatory obstruction of the bronchioles
Define asthma
hypersensitivity, increased mucus production, bronchoconstriction
Define emphysema
enzyme digestion of proteins like elastin leading to increased compliance; abnormal permanent enlargement of gas exchange airways accompanied by destruction of alveolar walls
Distinguish between primary vs. secondary emphysema. What is the prevalence of each?
□ Primary emphysema: results from inherited deficiency of an alpha-1 antitrypsin that inhibits the action of proteolytic enzymes which chew elastin (1-2% of cases)
Secondary: caused by inability of body to inhibit proteolytic enzymes (common), due to toxins, smoking
Define restrictive disorder, identify the best indicator, and what would a PFT look like?
characterized by lungs that are difficult to inflate
Decreased compliance = best indicator
PFT: Tidal volume and vital capacity correspondingly decreased
Decreased FEV1 and FVC, but ratio may be normal or increased
Define pulmonary fibrosis
Excess CT, elastin
What are causes of pulmonary fibrosis (5)?
secondary to other diseases involving autoimmunity, infection or injury or idiopathic, environmental pollutants (asbestos, cigarettes)
S/S of pulmonary fibrosis (7)
SOB (progressive), cough, fatigue, weakness, chest discomfort, loss of appetite, rapid weight loss
Consequences of pulmonary fibrosis (3)
- Exchange of parenchymal tissue with fibrotic tissue
- Increased thickness of resp membrane and reduced efficiency of gas exchange
- Overall ability to provide O2 to blood is compromised
Define pulmonary edema
Excess fluid in extravascular spaces of the lungs that restricts expansion
What is pulmonary edema a common complication of?
cardiac disorders, chronic or acute
What are risk factors for pulmonary edema (3)?
heart disease, ARDS, inhalation of toxic gases
Define pneumonia
infection of lower respiratory tract by microorganisms
Define pulmonary embolism, what are the typical causes (4)
Pulmonary embolism: occlusion of portion of vascular bed by embolus
Causes: Thrombus, tissue fragment, lipids, air bubble
Major consequence of pulmonary embolism
backflow of blood to R ventricle and increased HTN, increased jugular venous pressure, fluid imbalances, decreased gas exchange (hypoxemia)
Sx of pulmonary embolism (2) What impacts the degree of symptoms?
dyspnea, tachypnea with severe chest pain,
size impacts the degree of symptoms
Define pulmonary hypertension
HTN in pulmonary arteries, secondary to increased volume or pressure of blood or narrowing/obstruction of vessels
Define cor pulmonale
right ventricular enlargement secondary to pulmonary HTN caused by disorders of lungs or chest wall
Define acute respiratory failure, causes
inadequate gas exchange
Causes: direct injury to lungs, airways, chest wall, or indirectly to brain
Define acute respiratory distress syndrome (ARDS)
fulminate form of respiratory failure characterized by acute lung inflammation, diffuse alveolocapillary injury
What are risks for developing acute respiratory distress syndrome (ARDS)? (6)
Pneumonia, near drowning, toxins, DIC, infection, trauma
Lung cancers arise from the _________ of the __________ and are most commonly caused by _______
- epithelium
- respiratory tract
- cigarette smoking
Distinguish between small cell and non-small cell lung cancer
Small cell: rapid growing with early and widespread metastasis (25% of cases)
Non-small cell (adenocarcinoma, squamous cell, large cell): slower growing, does not typically metastasize (75% of cases)
