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Chapter 22
Disorders of Ventilation & Gas Exchange
68
Physiology
Not Applicable
07/13/2008

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Term
What is the function of the pleura?
Definition
It encases the lung
Term
Describe the causes and characteristics of pleuritic chest pain.
Definition
Caused by: primary pleural disorders, such as neoplasms or inflammatory disorders affecting the pleura or pulmonary disorders that extend to the pleural surface such as pneumonia

Characteristics:
-Pain is of abrupt onset, unilateral and localized to the lower part of the chest
-Pain is referred to the shoulder when the pleura that covers the diaphragm is irritated
-Pain is made worse with deep breathing and coughing
Term
Pleural effusion refers to what?
May be what type of fluid?
Definition
Refers to: an abnormal collection of fluid in the pleural cavity

fluid: may be transudate, exudate, purulent drainage (empyema), chyle or blood
Term
List 5 mechanisms and examples that can cause pleural effusion
Definition
1) Increased capillary pressure--as in congestive heart failure
2) Increased capillary permeability--in inflammatory conditions
3) Decreased colloidal osmotic pressure--like hypoalbuminemia in liver disease & nephrosis
4) Increased negative interpleural pressure--develops with alectasis
5) Impaired lymphatic drainage of the pleural space--because of obstructive processes like mediastinal carcinoma
Term
Pleural effusion:
Hydrothorax
Definition
Accumulation of a serous transudate (clear fluid) in the pleural cavity
Causes:
-Congestive heart failure
-Renal failure
-Nephrosis
-Liver failure
-Malignancy
Term
Pl
Definition
Term
Pleural Effusion:
Exudate
Definition
A pleural fluid that has a specific gravity greater than 1.020 and inflammatory cells
Causes:
-Infections
-Pulmonary infarction
-Malignancies
-Rheumatoid arthritis
-Lupus erythematosus
Term
Pleural Effusion:
Empyema
Definition
Purulent drainage (pus) in the pleural cavity

Causes:
- Direct infection of the pleural space from an adjacent bacterial pneumonia
- Rupture of a lung abscess into the pleural space
- Invasion from a subdiaphragmatic infection
- Infection associated with trauma
Term
Pleural effusion:
Chylothorax
Definition
Effusion of lymph in the thoracic cavity (common in cancer patients

Causes:
- Trauma
- Inflammation or malignant infiltration of the thoracic duct that transport chyle to the central circulation
- As a complication of intrathoracic surgical procedures and use of the great veins for total parenteral nutrition & hemodynamic monitoring
Term
Pleural Effusion:
Hemothorax
Definition
The presence of blood in the pleural cavity

Causes:
- Chest injury
- Complication of chest surgery
- Malignancies
- Rupture of a great vessel such as an aortic aneurysm
Term
Describe the manifestations of Pleural Effusion
Definition
-Dyspnea (most common
-Decreased lung expansion
-Shift if mediastinal structures
-Diminished breath sounds
-SOB
-Fever
-Inflammation
-Dullness
-Flatness or percussion
Term
Pneumothorax
Definition
AIR in the pleural cavity causing partial or complete collapse of the affected lung
Term
Spontaneous Pneumothorax
Definition
-Occurs when an air filled bleb or blister on the lung surface ruptures

-Pathophysiologically: this allows atmospheric air from airways to enter the pleural cavity, causing air to flow into the pleural space, causing the lung to collapse

-Primary spontaneous pneumothorax happens mostly in tall males between 10 and 30 years

-Secondary spontaneous pneumothorax occurs in persons with lung disease
Term
Traumatic Pneumothorax
Definition
May be caused by penetrating or nonpenetrating chest injuries and is often accompanied by hemothorax
for example:
-knife or gun shot wound
-fracture or dislocated ribs or ruptured esophagus
Term
Tension Pneumothorax
Definition
-Occurs when the intrapleural pressure exceeds atmospheric pressure
-Air enters, but cannot leave the pleural space
Term
What does a tension pneumothorax result in?
Definition
1) Rapid increase in pressure in the chest with a compression atelectasis of the unaffected lung
2) A shift in the mediastinum to the opposite side of the chest
3) Compression of the vena cava with impairment of venous return to the heart
Term
Tension Pneumothorax is a life threatening disorder. It is very important to be able to recognize the manifestations, such as:
Definition
-Decreased venous return
-Decreased cardiac output
-Distention of the neck veins
-Increased respiratory rate
-Increased heart rate
-Decreased breath sounds or absent breath sounds
-Dyspnea
Term
Why is a tension pneumothorax life threatening?
Definition
Because it causes the lung to collapse and compresses the vena cava
Term
Clinical Features of Pneumothorax:
Definition
-Manifestations depend on size and integrity of lung tissue
-Ipsilateral chest pain occurs in spontaneous pneumothorax
-Manifestations affecting all pneumothoraces include increased respiratory rate, dyspnea and increased heart rate as well as asymmetry of chest movement due to air trapping on affected side and hypoxemia
Term
Atelectasis refers to:
Definition
Incomplete expansion of a lung or portion of a lung
Term
What can atelectasis be caused by?
What is the most common cause?
Definition
Can be caused by airway obstruction, lung compression and increased recoil of the lung due to inadequate surfactant


-Most common cause is airway obstruction
Term
Give an example of airway obstruction and of lung compression leading to atelectasis
Definition
-Airway obstruction: mucus plug in the airway or by external compression of fluid; tumor mass; exudate or other matter in the area surrounding the airway

-Lung compression: when pleural cavity is partially or completely filled with fluid, exudate, blood, tumor mass or air.
Term
Describe the manifestations of atelectasis
Definition
-Tachypnea
-Tachycardia
-Dyspnea
-Cyanosis
-Signs of hypoxemia
-Diminished chest expansion
-Absence of breath sounds
-Intercostal retractions
-Fever
Term
Obstructive airway disorders are caused by disorders that increase...???
Definition
Resistance to airflow
Term
Bronchial Asthma
What is the common denominator of all forms of asthma?
Definition
An exaggerated hypersensitivity response to a variety of stimuli
Term
Bronchial Asthma: Extrinsic (Atopic) Asthma is typically induced by what?

What other disorders to people with this type of asthma often have?

What are the allergens implicated in this type of asthma?
Definition
-by a type 1 hypersensitivity reaction induced by exposure to an extrinsic antigen or allergen

-often also have hay fever, hives and eczema

-house dust mite allergens, cockroach allergens, animal danders and the fungus Alternaria
Term
Differentiate between the acute/early and late phase responses of asthma: ACUTE/EARLY RESPONSE
Definition
-It develops within in 10-20 minutes
-Caused by the release of chemical mediators from the presensitized mast cells
-Causes immediate bronchospasm, mucosal edema and increased mucosal secretions and inflammatory cells to infiltrate in submucosal mast cells
Term
Differentiate between the acute/early and late phase responses of asthma: LATE PHASE RESPONSE
Definition
-Develops 4-8 hours after exposure to trigger
-Involves inflammation and increased airway responsiveness that prolong the asthma attack and set into motion a vicious cycle of exacerbations
-Inflammation leads to edema, epithelial injury, impaired mucociliary function, increased airway responsiveness and airflow inflammation
Term
Bronchial Asthma: Intrinsic (Nonatopic) Asthma
List the nonatopic triggers
Definition
-Respiratory tract infections
-Exercise
-Hyperventilation
-Cold air
-Exercise
-Drugs and chemicals
-Hormonal changes
-Emotional upsets
-Airborne pollutants
-GERD
Term
Correlate the pathophysiological mechanisms of bronchial asthma to the clinical features.
Definition
Wide range from EPISODIC WHEEZING & FEELINGS OF CHEST TIGHTNESS to an ACUTE, IMMOBILIZING ATTACK.
Term
Correlate the pathophysiological mechanisms of bronchial asthma to the clinical features.
Why is asthma worse at night?
Definition
Because of the occurrence of the late response to allergens inhaled during the evening and because of circadian variations in bronchial activity
Term
Correlate the pathophysiological mechanisms of bronchial asthma to the clinical features.
What happens in the airways during an acute asthmatic attack?
Definition
-The airways narrow due to bronchospasm, edema of the bronchial mucosa and mucus plugging

-Expiration becomes PROLONGED due to airway obstruction

-FEV 1.0 and PEF are DECREASED

-With a prolonged attack, what happens to the lung?
--HYPERINFLATION OF THE LUNGS AND AN INCREASE IN THE RESIDUAL VOLUME

-It ultimately results in dyspnea, fatigue, ineffective cough, mismatching of ventilation and perfusion which lead to hypoxemia and hypercapnia
Term
Describe the clinical MANIFESTATIONS of asthma
Definition
MILD ATTACK: feeling of chest tightness, a slight increase in respiratory rate with prolonged expiration and mild wheezing, cough

SEVERE ATTACK: associated with the use of the accessory muscles, distant breath sounds caused by air trapping an loud wheezing; fatigue develops, skin becomes moist and anxiety and apprehension are obvious; dyspnea may be severe, markedly decreased airflow, breath sounds become inaudible with diminished wheezing and the cough becomes ineffective despite being repetitive & hacking; leads to respiratory failure
Term
SEVERE ASTHMA:
1) Identify the population most at risk for fatal asthma attacks

2) Identify the probable causes of death during an acute asthmatic attack
Definition
1) Those with previous exacerbations resulting in respiratory failure, respiratory acidosis and the need for intubation

2) Cardiac dysrhythmias, and asphyxia due to severe airway obstruction have been implicated
Term
Bronchial asthma in children:
-Is it common?
-How are symptoms different from those in an adult?
Definition
- Yes, it's the leading cause of chronic illness in children

- Symptoms: cold with rhinorrhea, rapidly followed by IRRITABILITY, a tight nonproductive cough, wheezing, tachypnea, dyspnea w/prolonged expiration and use of accessory muscles of respiration, cyanosis, inflation of chest and tachycardia
Term
CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD):
-Denotes a group of...

-Most common cause is...
Definition
-Group of respiratory disorders characterized by chronic and recurrent obstruction of airflow in the pulmonary airways

-Smoking
Term
List the 3 mechanisms involved in the pathogenesis of COPD
Definition
1) Inflammation and fibrosis of the bronchial wall

2) Hypertrophy of the submucosal glands & hypersecretion of mucus

3) Loss of alveolar tissue and elastic lung fibers
Term
Compare and contrast the mechanisms, causes and manifestations of emphysema and chronic bronchitis:
EMPHYSEMA:
characterized by...
causes...
Definition
-Characterized by a loss of lung elasticity and abnormal enlargement of the air spaces distal to the terminal bronchioles with destruction of the alveolar walls and capillary beds

-Caused by smoking; inherited deficiency of alpha 1 antitrypsin (which protects lungs from injury), which causes the breakdown of elastin and other alveolar wall components by enzymes, called proteases, that digest proteins--therefore the alveolar elasticity is lost
Term
Compare and contrast the mechanisms, causes and manifestations of emphysema and chronic bronchitis:
CHRONIC BRONCHITIS:
Affect who most commonly?
What qualifies diagnosis?
Earliest feature is what?
Definition
-It is airway obstruction of the major and small airways

-It most commonly affects middle aged men that smoke

-A history of chronic productive cough for at least 3 consecutive months in at least two consecutive years qualifies a diagnosis

-Earliest feature is hypersecretion of mucus in the large airways, associated with hypertrophy of the submucosal glands in the trachea and bronchi
Term
Clinical features of Emphysema and manifestations:
Definition
-Patients with emphysema are often called PINK PUFFERS (due to increased breathing and increased work to breath). There is not a ventilation-perfusion mismatch, both are proportionately lost. They overventilate to maintain fairly normal BLOOD GAS LEVELS.

-dramatic barrel chest due to hyperinflation of the lungs (b/c can't comletely exhale)
-severe weight loss in advanced disease
-shortness of breath
-decreased breathing sounds
-slowly debilitating disease
Term
Clinical features of chronic bronchitis and manifestations:
Definition
-Patients with chronic bronchitis are called BLUE BLOATERS. There is a ventilation-perfusion mismatch, they are unable to increase their ventilation to maintain normal ABGs.
- So, CYANOSIS develops

- barrel chest may be present
-shortness of breath
-variable decreased breathing sounds
-variable wheezing
-prominent Rhonchi
-sputum
-dramatic cyanosis
-hypercapnia
-hypoxemia
-frequent cor pulmonale, leads to peripheral edema
-polycythemia--b/c the chronic SOB leads to hypoxemia and stimulates RBC production
-life threatening
Term
Cystic fibrosis
Definition
-It is an autosomal recessive disorder involving fluid secretion in the exocrine glands in the epithelial lining of the respiratory, GI and reproductive tracts

-It is the most common fatal hereditary disorder of whites in the U.S. and the most common cause of lung disease in children
Term
Cystic fibrosis: Clinical Features
Definition
-Respiratory manifestations are caused by: an accumulation of mucus in the bronchi, impaired mucociliary clearance and lung infections, airway obstruction

-Pancreatic exocrine deficiency--pancreatic function is abnormal in 80%-90% causing steatorrhea, diarrhea and ab pain and discomfort
Term
Chronic interstitial lung disease:
Definition
A diverse group of lung disorders that produces similar inflammatory and fibrotic changes in the interstitium or interalveolar septa of the lung

-Examples: hypersensitivity pneumonitis, lung disease caused by exposure to toxic drugs and radiation, sarcoidosis and occupational lung diseases including the pneumoconioses that are caused by the inhalation of inorganic dusts such as silica, coal dust and asbestos
Term
PATHOGENESIS of Chronic Interstitial Lung Disease
Definition
It's initiated by some type of injury to the alveolar epithelium, followed by an inflammatory process that involves the alveoli and interstitium of the lung
An accumulation of inflammatory and immune cells causes continued damage of lung tissue and the replacement of normal, functioning lung tissue with fibrous scar tissue
It's usually associated with airway obstruction
Term
Clinical features and symptoms of Chronic Interstitial Lung Disease
Definition
-NO evidence of wheezing or signs of airway obstruction
-Dyspnea, tachypnea, eventual cyanosis, insiduous onset of breathlessness that occurs with exercise and may progress to total incapacitation, non productive cough, respiratory rate increases, tidal volume decreases and reduced work in breathing
Term
Pulmonary Vascular Disorders--PULMONARY EMBOLISM
Where do these come from?
Who is at risk?
Definition
- Most come from DVT in the lower extremities

- People venous stasis, venous endothelial injury and hypercoagubility states, oral contraceptives, pregnancy, hormone replacement therapy, orthopedic surgery, prolonged bed rest, trauma, surgery, child birth, fractures of the hip and femur, MI, congestive heart failure spinal cord injury
Term
Pulmonary Vascular Disorders--PULMONARY EMBOLISM
Manifestations
Definition
-Chest pain, dyspnea and increased respiratory rate are most common

-Pleuritic pain occurs with pulmonary infarction

-Moderate PE: breathlessness, pleuritic pain, apprehension, slight fever, rapid and shallow breathing and cough productive of blood streaked sputum

-Massive PE: sudden collapse, crushing substernal chest pain, shock and sometimes loss of consciousness, rapid & weak pulse, low blood pressure, distended neck veins, skin is cyanotic and diaphoretic; often fatal
Term
PULMONARY HYPERTENSION
Definition
-A low pressure system designed to accommodate varying amounts of blood delivered to the right heart and to facilitate gas exchange

-Defined as a sustained elevation of the mean pulmonary artery pressure to more than 25 mmHg at rest or more than 30 mmHg w/exercise
Term
What factors can cause pulmonary HTN?

Does pulmonary HTN increase or decrease the workload of the right heart?
Definition
-elevation in left atrial pressure
-increased pulmonary blood flow
-increased pulmonary vascular resistance

-It increases workload of the right heart
Term
SECONDARY PULMONARY HTN:
List the 4 mechanisms and list an example
Definition
1) Elevation of pulmonary venous pressure: mitral valve stenosis and LV heart failure

2) Increased pulmonary blood flow: congenital heart diseases--atrial or ventricular septal defects and patent ductus arteriosus

3) Pulmonary vascular obstruction: pulmonary emboli

4) Hypoxemia: COPD
Term
SECONDARY PULMONARY HTN:
List the signs and symptoms and give the rationale
Definition
-dyspnea, fatigue, peripheral edema, ascites, signs of right heart failure (cor pulmonale)

-reflects not only the underlying cause by also the effect that the elevated pressure has on right heart function and oxygen transportation
Term
Primary Pulmonary HTN
Definition
-Rare
-May be due to genetic predisposition
Term
Cor pulmonale
Definition
Refers to right heart failure resulting from primary lung disease and long standing primary or secondary pulmonary hypertension
Term
Manifestations of Cor pulmonale
Definition
-Those of primary lung disease and right sided heart failure

-venous congestions, peripheral edema, SOB, productive cough, plethora (redness), cyanosis and warm, moist skin, and drowsiness and altered consciousness
Term
ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)
Definition
-The common pathway that many serious localized and systemic disorders produce diffuse injury to the ALVEOLAR-CAPILLARY MEMBRANE. Fluid moves into the lungs due to the increased permeability of the alveolar-capillary membrane

-Diffuse epithelial cell damage with increased alveolar-capillary membrane permeability causes fluid, protein, cell debris and blood cells to move into the interstitium and alveoli of the lung, which causes fluid to accumulate, surfactant to inactivate, and hyaline membrane to form. The lungs then become STIFF AND DIFFICULT TO INFLATE, leading to increased intrapulmonary shunting and impaired gas exchange and profound HYPOXIA
Term
RESPIRATORY FAILURE:
Causes
Definition
Essentially, there is not enough OXYGEN (hypoxemia) and too much CO2 (hypercapnia)

Causes:
-Hypoventilation
-Ventilation-Perfusion Mismatching
-Impaired diffusion
Term
Respiratory Failure
Hypoventilation
Definition
- Occurs when the volume of fresh air moving into and out of the lungs is significantly reduced

-Commonly caused by conditions outside of the lung such as depression of the respiratory center, drug overdose, high flow oxygen therapy in persons with COPD; diseases of the nerves supplying the respiratory muscles (muscular dystrophy) or thoracic cage disorders (severe scoliosis or crushed chest)
Term
Respiratory Failure
Ventilation-Perfusion Mismatching
Definition
Occurs when areas of the lung are ventilated but perfused or when areas are perfused but not ventilated
Term
Respiratory Failure
Impaired diffusion
Definition
Condition in which gas exchange between the alveolar air and pulmonary blood is impeded b/c of an increase in the distance for diffusion or a decrease in the permeability of the respiratory membranes to the movement of gases
causes: interstitial lung disease, ARDS, pulmonary edema and pneumonia
Term
Manifestations of Respiratory Failure

Hypoxemia
Definition
-Generally ABGs of PO2 less than or equal to 60 mmHg and PCO2 greater than or equal to 50 mmHg may indicate respiratory failure, assuming other clinical manifestations support the diagnosis

-Slight impairment of mental performance and visual acuity, hyperventilation, personality changes, restlessness, agitated or combative behavior, uncoordinated muscle movements, euphoria, impaired judgement, delirium and eventually stupor and coma; increased HR, peripheral vasoconstriction, diaphoresis, mild increase in BP, cyanosis
Term
Manifestations of Respiratory Failure

Hypercapnia
Definition
-Generally ABGs of PO2 less than or equal to 60 mmHg and PCO2 greater than or equal to 50 mmHg may indicate respiratory failure, assuming other clinical manifestations support the diagnosis

-Decrease in pH and respiratory acidosis, direct vasodilating effect on many blood vessels, sedative effect of the nervous system, increase cerebral blood flow causing headache, increased cerebrospinal fluid pressure and papilledema, hyperemic conjunctiva, warm and flushed skin, nervous system effects similar to those of an anesthetic, somnolence, disorientation, coma, mild to moderate increase in BP, air hunger and raid breathing, lethargy and anesthesia and death
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