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144 Cards in this Set
- Front
- Back
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What are the three processes of gas exchange?
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alveolar ventilation
diffusion: oxygen into the blood and carbon dioxide out perfusion: oxygen into the tissues and carbon dioxide out of the tissues |
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What things can increase metabolic demand for oxygen?
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exercise, cold stress, or disease
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What physical exam findings (in addition to normal blood gas levels) indicate a normal respiratory system?
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no excessive discharges
little abdominal component to respirations pink mucous membranes no obvious respiratory effort alert- good body condition respiratory rate and depth wnl symmetrical facial structures, chest movements and breath sounds normal lung borders on percussion inability to elicit cough by laryngeal palpation |
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What might be the first signs of disruption in respiration?
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alterations in the rate or depth of breathing (ventillation) or cardiac output (perfusion)
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What is hypoxemia and hypercarbia?
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low partial pressure of oxygen in arterial blood
high partial pressure of carbon dioxide in arterial blood |
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What does lethargy or exercise intolerance indicate about possible respiratory issues?
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it indicates that gas exchange can not keep up the metabolic demand of running or walking
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What are characteristic alterations in posture indicative of a respiratory issue?
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crouched cats, head-down cows with front legs splayed, indicating an attempt by the animal to make breathing more comfortable
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What does cyanosis indicate?
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it indicates that there is excessive unoxygenated hemoglobin in the arterial blood
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What are the three major categories of the respiratory system?
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upper airway (nares to larynx); lower airway (trachea to alveoli); and chest (pleural space outward)
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What are common problems with the upper airway?
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sinusitis, pharyngitis, laryngitis
foreign bodies laryngeal/pharyngeal disorder gutteral pouch disorders in equids possible dental problems |
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What are common problems with the lower airway?
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tracheobronchial disorders or parenchymal disorders- either alveolar or intersitial
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What are common problems with the chest?
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pleural disorders, such as effusions
disorders of the ribs or diaphragm disorders of the originating in the mediastinum cardiac disorders |
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What diagnostic procedures are used to distinguish among the various potential causes of respiratory signs and symptoms?
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history
physical exam palpation of nose, neck, thorax and abdomen sampling of fluids, cells, or tissues, serological/ fecal analysis/ clinical chemistry response to therapy |
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How would you treat cough?
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antitussives
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How would you treat hypoxemia?
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oxygen therapy, mechanical ventilation, bronchodilation, surgery
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How would you treat pulmonary edema?
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diuretics
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How would you treat a wet cough?
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expectorants
hydration- systemic or local through nebulization |
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How do you treat reactive airways?
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corticosteriods
immunotherapy mast cell stabilizers environmental management |
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How do you treat infection?
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antivirals
antibiotics antiparasiticides environmental management |
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How do you treat hypoventilation?
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respiratory stimulants
mechanical ventilation |
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What are the other functions of the respiratory system (other than gas exchange)?
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phonation (voice change), olfaction, thermal regulation, defense mechanisms to maintain structural integrity, also in metabolizing endogenous or exogenous substance in the blood (positive or negative)
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What are the three categorical causes of hypoxemia?
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low inspired oxygen, venous admixture, and hypoventilation
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Why is scar tissue formation in the lungs particularly detrimental?
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it prevents gas exchange
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What is the purpose of the anatomical arrangement of the nasal passages?
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it warms and humidifies the inspired air and traps/removes large particles
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What is the most important defense mechanism in the alveoli?
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the alveolar macrophates that isolate potential antigens from immune competent tissues, kill bacteria, and transport debris from the alveolar surface to the lymphatic system. They are derived from bone marrow monocytes, are highly mobile, are highly phagocytic and have a 1-5 week lifespan
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What is the process of the inflammatory response in the lung?
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inflammation causes increased blood flow and increased endothelial permability that enhances the accumulation of neutrophils and eosinophils which can in turn recruit additional inflammatory cells
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What are the immune competent tissues in the lungs?
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lymph nodes, lymph nodules and lymphoid aggregates and infiltrates
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Where are the lymph nodes of the respiratory system located?
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at the hilus and in the trachea and major bronchi
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What type of immune competent tissue is found in large and mid-sized bronchi?
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BALT- bronchus associated lymphoid tissue
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What are the components of humoral immunity int he lung?
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lung contains B cells that produce IgA (fluid of the upper respiratory tract), IgG (lower respiratory tract), not much IgM, IgE in response to allergies
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What is the cell-mediated immunity of the lung?
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it has T-cells that can produce lymphokinds like chemotactic factors, migration inhibition factor and macrophage activation factors; also pulmonary cytotoxic T cells defend against neoplasms and are important in graft vs host diseases
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What is Dalton's law of partial pressures?
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Px = Pb x Fx
each gas acts as if it were alone and provides a partial pressure in proportion to the fractional number of molecules of that gas and the barometric pressure |
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What is the driving force for oxygen moving from the alveoli to the pulmonary capillary?
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the partial pressure of oxygen in the alveolar gas is greater than that in the pulmonary blood so the oxygen diffuses into the blood from the alveoli
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What is the difference between bulk flow and diffusion?
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diffusion occurs when there is a difference in partial pressure of the gas; bulk flow occurs when there is a difference in total pressure
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What are the normal partial pressures of atmospheric air?
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Nitrogen- 0.78
Oxygen- 0.21 Carbon dioxide- 0.03 Miscellaneous gases- 0.01 |
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How would you theraputically treat hypoxemia?
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increase the fraction of inspired oxygen which will increase the partial pressure of oxygen in the alveoli and promote the diffusion of oxygen into the pulmonary capillary blood
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What are the important gases in the alveoli?
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water, carbon dioxide, oxygen and nitrogen
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Why are alveolar gas pressures usually reported "dry"?
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water vapor pressure depends on temperature and therefore varies
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What is the partial pressure of water vapor at 37C?
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47mmHg
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What is the formula for calculating the partial pressure of oxygen in the alveoli?
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PAO2= PI02 - (PACO2/R)
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What is "R" in the equation for calculating partial pressure of oxygen in the alveoli?
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it is the ratio between the amount of carbon dioxide in the alveoli from the pulmonary capillary blood and the amount of oxygen leaving the laveoli by diffusing into the capillary blood
We use R=0.8 |
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Why, if the partial pressure of carbon dioxide in the alveoli and arterial blood are equal, are the oxygen partial pressures not equal in the alveoli and arterial blood?
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because the physical properties of oxygen are different than those of carbon dioxide
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What is the difference between arterial PO2 and alveolar PO2?
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arterial PO2 is usually slightly less than pulmonary capillary PO2 because of right to left vascular shunts that add venous blood to the arterial circulation
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What is "venous admixture"?
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it is the shunt that allows less than 5% of total blood flow to shunt from right to left- venous blood into the arterial blood
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What is AaDO2?
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"Alveolar-arterial oxygen difference"- the magnitude can increase with disease and can be estimated clinically to help differentiate among causes of hypoxemia
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How do you estimate the AaDO2?
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If lungs work well arterial PO2 should be 5 times the inspired O2
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What radiographic technique should be used to examine the lungs?
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high kVp (85-100+), low mAs (exposure time) and made at peak inspiration
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What are the routine radiographic projections when looking at lungs in large animals, small animals, and foals?
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large: four lateral projections
small: one lateral, VD/DV foal: 2 lateral projections, VD if animal is small enough |
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What projections should be done when looking for metatstatic disease?
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right and left lateral, VD/DV
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What are the pulmonary patterns of disease in the lungs?
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vascular, bronchial, interstitial, alveolar
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What is a vascular pattern in the lungs?
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it is an increased or decreased prominence of the pulmonary vasculature
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What is the radiographic appearance of a bronchial pattern?
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"doughnuts" and "tram lines"
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What can cause a bronchial pattern?
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fluid and/or cellular material within the bronchial wall, lumen or peribronchial space
chronic inflammation and hypersensitivity mineralization |
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What is bronchiectasis?
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increased diameter of the bronchus- usually has another pattern along with it
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What is an interstitial radiographic pattern?
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it is an accumulation of fluid and/or cells in the pulmonary interstitial space or connective tissue between the airway and alveoli
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What does an unstructured pulmonary interstitial pattern look like radiographically?
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it is a soft tissue haze that obscures the pulmonary vasculature
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How does a structured interstitial pattern appear radiographically?
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it appears as round, soft tissue opacities due to an aggregation of cells within the interstitum
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How do you diagnose the cause of a bronchial pattern?
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trans-tracheal wash
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How do you diagnose the cause of a structured interstitial pattern?
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fine needle aspirate
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What causes an alveolar pattern on radiographs?
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displacement of air from the distal space of the lung due to:
flooding of the pulmonary acini acini connected by pores that allow the fluid to spread pus, edema or blood collapse of the airway |
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What do alveolar patterns appear like radiographically?
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"air bronchograms"- gas filled large and medium sized bronchi surrounded by soft tissue opacity
bronchial walls and vessels are not seen |
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How do you diagnose the cause of an alveolar pattern?
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transtracheal wash or bronchoalveolar lavage
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If an entire lung lobe has a soft tissue opacity, what type of radiographic pattern is it?
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alveolar
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What are the causes of artifacts on small animal lung radiographs?
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underexposure, making films during expiration, overexposure
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What are the primary differentials for structured/nodular non-cavitated interstitial patterns?
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pulmonary metastasis
fungal pneumonia primary lung tumor |
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What do pulmonary metastases look like radiographically?
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multiple round, soft tissue nodules of various sizes usually in the middle to peripheral aspect of the lungs
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What does fungal pneumonia look like radiographically?
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nodular pattern throughout the lungs- miliary sized nodules if very small, all nodules usually the same size
tracheobronchial lymphadenopathy frequently seen |
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What do primary lung tumors look like radiographically?
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usually solitary, usually arise in the periphery
can be cavitated if it communicates with a bronchus need cytology to confirm |
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What are the primary differential diagnoses for primary lung tumors?
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metastatic tumor
pulmonary granuloma pulmonary abscess traumatic cysts |
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What are the differentials for a cavitated, structured interstitial pattern?
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pulmonary abscess
paragonimiasis pulmonary bulla |
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What does a pulmonary abscess look like radiographically?
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focal, walled-off septic matter (inhaled foreign body, local inflammation)
thick, irregularly margined wall |
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How do you diagnostically confirm a pulmonary abscess?
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cytology
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What is paragonimiasis and what does it look like radiographically?
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lung flukes
well defined pulmonary masses with central lucency flukes inhabit interstitial space adjacent to the bronchus |
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What do pulmonary bulla look like radiographically?
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spherical radiolucent areas, smooth thin walls
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What are the causes of pulmonary bullas?
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congenital
traumatic (contain fluid too) infectious |
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What happens if a pulmonary bulla ruptures?
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pneumothorax, pneumomediastinum
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What is a pulmonary bleb?
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it is a pulmonary bulla in a subpleural location
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What are the differentials for an unstructured interstitial/ alveolar pattern?
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geriatric thorax
pulmonary edema- cardiogenic or non-cardiogenic atelectasis pulmonary hemorrhage/contusion bacterial pneumonia aspiration pneumonia pulmonary embolism lung lobe torsion |
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What causes a geriatric thorax and what radiographic pattern does it exhibit?
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interstitial fibrosis that depends on the amount of pollutants inhaled or a scar from a previous lesion
it appears like an unstructured interstitial/alveolar pattern |
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What causes cardiogenic pulmonary edema and what type of radiographic pattern does it exhibit?
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secondary to left heart failure and is distributed to the hilar and perihilar regions
more common than non-cardiogenic causes signs of heart and pulmonary vein enlargement exhibits unstructured interstitial/ alveolar pattern |
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What are the causes of non-cardiogenic pulmonary edema?
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neurologic- head trauma, seizure, electric shock
severe allergic reaction advanced uremia pancreatitis irritating inhalants drowning radiation damage |
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How can you distinguish cardiogenic from non-cardiogenic pulmonary edema?
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non-cardiogenic has a more generalized distribution and does not show cardiac signs. peripheral distribution is more common
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What can cause atelectasis on a radiograph?
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decreased air within a lung lobe due to:
incomplete aeration airway obstruction increased intrapleural pressure |
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How can you differentiate pulmonary hemorrhage/ contusion from the other causes of unstructured interstitial/ alveolar lung patterns?
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look for other signs of trauma- rib fractures, pleural effusion, pneumothorax, diaphragmatic hernia
coagulopathy |
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How does bacterial pneumonia differ from aspiration pneumonia radiographically?
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bacterial pneumonia is usually lobar or hematogenous causes a patchy, multifocal distribution
aspiration pneumonia is usually in the right cranial, right middle or right caudal lobe and is often associated with megaesophagus |
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Which lung lobe is most commonly affected by aspiration pneumonia?
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the right middle lung lobe
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What factors influence the distribution of aspiration pneumonia?
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patient position at the time of aspiration:
passive: right cranial, right middle forceful: right caudal |
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If a pulmonary embolism is suspected, what other diagnostics need to be done?
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pulmonary angiography
pulmonary scintigraphy |
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What causes lung lobe torsion and what does it look like radiographically?
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lung lobe twists on its axis in deep chested dogs
causes pleural effusion- venous supply is obstructed while arterial supply continues right middle lung lobe most commonly affected lung lobe sometimes has multiple gas bubbles in it or is consolidated an abrupt termination of the bronchus is a sign |
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What can cause a bronchial pattern on radiographs?
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allergic bronchitis
viral bronchitis bronchiectasis overexposure hypovolemia |
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What are the characteristics of allergic bronchitis?
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it occurs commonly in cats (feline asthma)
peribronchial infiltrate of eosinophils and mononuclear cells if severe, can get interstitial edema if chronic, can get interstitial fibrosis |
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what are the causes of viral bronchitis in cats and dogs?
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dogs: tracheobronchitis
cats: upper respiratory disease |
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What is bronchiectasis?
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loss of normal bronchial tapering
changes in: bronchial epithelium mucus characteristics ciliary function exudate accumulates |
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What does hypovolemia look like radiographically?
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pulmonary vessels are very small
lack of vascular markings microcardia |
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What causes focal pulmonary mineralization?
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bronchial mineralization
pulmonary osteomas granulomas histoplasmosis primary lung tumor aspirated barium sulfate |
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What causes diffuse pulmonary mineralization?
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hyperadrenocorticism
hyperparathyroidism chromic uremia idiopathic |
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What are the common large animal respiratory diseases?
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bacterial pneumonia
Rhodococcus equi pneumonia pulmonary abscesses chronic obstructive pulmonary disease |
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What differentiates bacterial pneumonia in large animals?
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it is usually a bilateral, ventral distribution and causes an interstitial/alveolar pattern with possible abscess or granuloma formation
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What disease of foals causes multiple "fluffy" soft tissue masses that may be cavitated?
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Rhodococcus equi
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What radiographic abnormalities are found in large animals with COPD?
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air trapping- inspiration and expiration films are similar
reticulated interstitial pattern possible bronchiectasis |
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In an animal with anemia, why don't the chemoreceptors cause the animal to change breathing rate?
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the chemoreceptors only respond to free oxygen and CO2. Since the hemoglobin levels are low in anemia, the majority of the oxygen will be free in the blood and therefore the chemoreceptors will not be triggered
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What is the rule of thumb for PaO2 compared to % inspired oxygen?
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should be about 5x inspired oxygen % ie if breathing 100 O2, value should be about 500
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How can you change the PI02 ( the partial pressure of inspired oxygen)?
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by changing the barometric pressure or the fraction of inspired oxygen
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What are the 2 kinds of respiratory problems?
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the lung itself (more likely 02 issue)
pump problem: likely issues with both O2 and CO2 |
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The minute-to-minute respiration rate is dependent on what gas pressure?
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PCO2- the aortic and carotid bodies are the only ones that respond to both PO2 and PCO2
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What are the physical responses to mechanical stimulation of the larynx?
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the larynx slams shut causing a cough
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What do animals frequently sigh?
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it resets the tension in the smooth muscles around the airways
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What are the alveolar "J" receptors?
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they are the juxtacapillary receptors in the alveoli that sense the amount of fluid in the interstitium- also respond to hot peppers
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Completely disordered breathing is a pathognemonic pattern for what disease?
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called biot's respiration and indicates a disorder in the medulla
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Bigger and bigger breaths then tapers, then a pause is a pathognemonic breath pattern for what?
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C-S low blood flow state
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What are Kusmol respirations?
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bigger breaths more frequently which can indicate metabolic acidosis (DKA)
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Why don't animals with anemia have changes to their respiratory rate (generally)?
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they have a decreased hemoglobin, so there will be plenty of free O2 in the blood and CO2 should be normal so the chemoreceptors will not be triggered even though there is not enough oxygen getting to the tissues
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What is the point of ventillation?
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it is to keep alveolar PO2 and PCO2 within normal limits
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What is required for ventillation?
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CNS
Motor Nerves respiratory muscles functional lungs intact chest wall |
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What determines the total lung capacity?
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it is how much muscle contraction is occurring vs chest wall resistance
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What is the vital capacity?
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it is the total amount of air you can move out of the lungs
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What is the functional residual capacity (FRC)?
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it is the balance point where everything is in equalibrium
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A large FRC (functional residual capacity) is halmark of what type of disorder?
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obstructive disorders
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What is the difference between alveolar dead space and physiological dead space?
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alveolar dead space is when the alveoli that should be participating in gas exchange are not
physiological dead space is a combination of the normal, anatomic dead space and the alveolar dead space |
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What are the factors that determine transpulmonary pressure?
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alveolar pressure and pleural pressure
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What generates the pressures surrounding the lung?
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the chest wall muscles
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What are the 2 ways you can change transpulmonary pressure?
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lower the pleural pressure relative to the alveolar or make the alveolar pressure larger relative to pleural pressure
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Why do the lungs collapse when you cut into the chest?
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the pleural pressure becomes equal to the atmospheric pressure and lungs collapse
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How can you get a pneumothorax without opening the chest wall?
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overexpanding the lung can cause it to pop and let air into the pleural space
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What main factor is required for ventillation to occur?
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a change in pressure that requires effort (your own or via a ventillator)
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What is the normal pressure in the pleural space?
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- 5mmH2O
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If you have a lung with a larger than normal dead space, how will it change tidal volume?
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tidal volume will be the same but less of the air will be participating in gas exchange
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How do you calculate the minute ventillation?
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multiply the rate of breathing times the tidal volume- ends with how much air moves in or out of the lungs in 1 minute
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What factor can be used to quantify alveolar ventillation and why?
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CO2 because there is no CO2 in inspired air so all the CO2 in the expired air comes from the pulmonary capillary blood in the functional alveoli
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If expired CO2 is decreased, what is this saying about lung function?
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it says there is less lung participating in gas exchange
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If CO2 is not going out of the lungs, where does it go?
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Arterial blood
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If arterial PO2 goes up, but you haven't changed how much is produced, what happened to ventillation?
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ventillation went down
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How do you calculate alveolar ventillation?
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amount of CO2 produced/ (K x partial pressure alveolar or arterial CO2)
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How can you fix high PCO2?
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increase the expiratory rate or increase tidal volume
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Why won't supplementing O2 fix a high PCO2?
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it will fix the hypoxemia, but it won't help the alveoli get rid of the CO2 that is being released
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What determines airway resistance?
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compliance of the alveoli
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What does the pressure-volume relationship curve tell us?
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describes how easy it is to expand the alveoli
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What generates the change in pressure that allows us to ventillate?
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the respiratory muscles
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How does the pressure-volume relationship curve differ between normal lungs and stiff lungs?
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in stiff lungs the pressure decreases much slower on expiration due to a decreased lung compliance
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What are examples of parenchymal disorders that cause decreased lung compliance?
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interstitial fibrosis and interstitial edema
as well as increased surface tension due to inadequate surfactant |
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Why is inadequate lung surfactant an issue for premies?
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it is produced by type II cells that develop late in gestation. Currently it is being treated with artifical sufactant
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What is the law of LaPlace and how does it apply to ventillation?
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the pressure of surface tension depends on the surface tension and the radius
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How does surface tension relate to radius size?
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as the radius gets smaller, the surface tension decreases
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What changes occur within the alveoli that increase surface tension?
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smaller alveoli, larger ducts, smaller area
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