Respiratory - Pulmonary Parenchymal Diseases Flashcards
Which is not included as pulmonary parenchyma? A) interstitium B) alveoli C) Microvasculature D) pleura
D - pleura
Primary function of the parenchyma is
gas exchange
The exchange or transfer of gas across the blood-gas barrier occurs by A) active transport B) osmosis C) diffusion D) no body knows
C - diffusion
Fick’s Law
the rate of transfer of a gas through a sheet of tissue is proportional to the tissue area and the difference in the partial pressure of gas on the two sides of the tissue and inversely proportional to tissue thickness
Bacterial pneumonia
bacterial infection within the pulmonary parenchyma
potential routes of infection causing bacterial pneumonia
inhaled, aspirated, extension from nearby tissues, hematogenous
T/F virulent primary pathogens are more common causes of bacterial pneumonia
false, opportunistic pathogens are more common so it is important to investigate for predisposing factors (immunosuppression, pre-existing respiratory disease, aspiration)
Common opportunistic pathogens of bacterial pneumonia in dogs
E. coli, pasteurella, klebsiella, staphylococcus, streptococcus, bordetella, mycoplasma
Common opportunistic pathogens of bacterial pneumonia in cats
mycoplasma, pasteurella, bordetella, streptococcus, E. coli
Virulent (primary) pathogens that can cause bacterial pneumonia
strep. equi subspecies zooepidemicus, extra intestinal E. coi
hemorrhagic or necrotizing pneumonia, parachute to acute, high mortality rate
Community Acquired Pneumonia (CAP)
develops in a patient that has not recently been hospitalized (and aspiration of gastric and oropharyngeal contents is not suspected
Hospital acquired pneumonia (HAP)
occurs >48h after hospital admission and was not incubating at the time of admission
Aspiration pneumonia
result of inhalation of gastric/oropharyngeal contents that are contaminated by pathogenic bacteria
T/F: treatment strategies for CAP, HAP and aspiration pneumonia are all similar
False, CAP and aspiration pneumonia similar but HAP differs
Signalment of bacterial pneumonia
dogs > cats, young or old but any age can be affected
no breed disposition
Common clinical signs of bacterial pneumonia
cough, exercise intolerance, nasal discharge, increased RR and effort, lethargy, hyporexia, pyrexia
Potential findings in a PE of an animal with bacterial pneumonia
abnormal lung sounds, tachypnea, dyspnea, nasal discharge, pyrexia, cyanosis, sinus arrhythmia (due to increased vagal tone)
Thoracic radiographs of a dog with bacterial pneumonia
classic pattern is alveolar, predominantly ventral
interstitial and/or bronchial markings may be present
diffuse distribution more common with hematogenous pneumonia
pneumonia associated with aspiration, foreign body or a tumor may only involve 1 lobe
Definitive diagnosis of bacterial pneumonia requires
identification of sepsis (neutrophilic inflammation and intracellular bacteria) from lower airway samples (obtained via transtracheal wash or bronchoalveolar lavage) followed by culture and sensitivity
mycoplasma ID requires special media or PCR
Common CBC findings in bacterial pneumonia
neutrophilic
When reading a pulse oximeter, a low (<95%) SpO2 suggests patient is _____
hypodermic and supplemental O2 should be given
What are arterial blood gas and pulse oximetry used for?
detecting hypoxia, measuring oxygenation
Which is FALSE regarding treatment of bacterial pneumonia?
A) antibiotics are mainstay of treatment and last usually 10-14d
B) Lower airway samples should be obtained prior to starting antibiotic therapy
C) One most always obtain a lower airway sample
D) Multidrug resistant pathogens are common in hospitals so patients with HAP are at increased risk of getting a MDR infection
C - don’t need to if patient has a CAP, no prior history of pneumonia and no recent history of having antibiotic therapy
Treatment of bacterial pneumonia in patients with late onset (>4d) HAP or otherwise at risk for having a MDR infection
1) 1st generation cephalosporin + 2nd or 3rd gen cephalosporin
2) carbapenem (B-lactam) or amikacin + amoxicillin/sublactam or ticarcillin/clavulanate
Adjunct treatment of bacterial pneumonia
supplemental O2 in hypoxic patients fluid therapy to maintain perfusion nebulization to enhance mucus fluidity coupage to encourage coughing of mucus bronchodilator and/or mucolytic not routine but may be helpful treatment of any predisposing causes
Mycotic pneumonia
blastomyces dermatitis, histoplasmosis capsulate, coccidioides immitis
lower resp signs + lymphadenopathy and weight loss
rads are nodular or military interstitial and perihilar lymphadenopathy
Diagnosis - sample skin or nodes cytologically, urine fungal antigen test
Tx - long term anti fungal therapy and supportive care
Blasto + history - itraconazole, Cocci - fluconazole or itraconazole
How would you diagnose a mycotic pneumonia? A) pulse oximetry and blood gas analysis B) transtracheal wash C) bronchoalveolar lavage D) cytology of skin and lymph nodes
D - cytology of skin and lymph nodes
Pneumocystitis carinii
associated with severe morbidity and high mortality in immunocompromised
common in mini daschunds and CKC spaniel
fever usually absent despite severe pneumonia
mycotic
Tx - potentiated sulfonamides and supportive care
Which type of pneumonia appears as a "snowstorm" on rads? A) bacterial B) Mycotic C) Viral D) protozoal
B - mycotic
Viral Pneumonia
primary pathogens and contagious
canine - parainfluenza, influenza, distemper, coronavirus, infectious hepatitis, herpesvirus
Cats - coronavirus, calicivirus, herpesvirus
D - PCR
Tx - supportive, antibiotic therapy if secondary bacterial infection suspected
Protozoal pneumonia
toxoplasma gondii most common, cats are reservoir
Dx - serology, tachyzoites may be in airway sample
Tx - potentiated sulphonamides or clindamycine
what is idiopathic pulmonary fibrosis (IPF)
an interstitial lung disease characterized by the presence of fibrosis - cause of fibrosis unknown
which breeds are predisposed to IPF?
wastes, strafforshire bull terrier, usually middle aged to older
cats - no breed disposition, any age affected
common clinical signs of IPF
cough, exercise intolerance, tachypnea, lethargy, syncope
PE reveals loud crackles in all fields
What do you expect to see on the Rads of an animal with IPF?
diffuse bronco interstitial pattern in dogs
in cats, bronchial, interstitial and alveolar patterns possible
if severe PH present, R sided cardiomegaly + PA enlargment
When is an echo indicated for IPF patients?
if PH suspected and to evaluate for concurrent primary cardiac disease
Definitive diagnosis of IPF requires
lung biopsy and histopathology
not normally done bc of risk
Which is FALSE regarding therapy of IPF?
A) cough suppressant therapy can help
B) Corticosteroids are contraindicated in treatment
C) No specific therapy available
D) Bronchodilators can improve clinical signs
B - corticosteroids can help improve clinical signs in some patients
What is non-cardiogenic pulmonary edema (NCPE)?
increased vascular permeability secondary to lung injury, is usually protein rich (in contrast to cariogenic pulmonary edema which is low in protein)
Hypoxemia during NCPE usually results from
alveolar fluid, decreased lung compliance, airway compression
Mechanisms of pulmonary edema
increased hydrostatic pressure, decreased oncotic pressure, increased vascular permeability, and/or impaired lymph drainage
2 categories of pulmonary edema
cardiogenic or non-cardiogenic
Causes of NCPE
acute respiratory distress syndrome secondary to primary pulmonary disease or secondary airway obstruction seizure electrocution vasculitis severe hypoalbuminemia
Clinical signs of NCPE
parachute or acute onset
tachypnea, exercise intolerance, dyspnea, cough, cyanosis, hemoptysis
depends on degree of pulmonary injury and amount of NCPE
increased BV sounds and/or crackles common auscultatory abnormalities
decreased lung sounds if edema severe
Treatment of NCPE
supplemental O2 in hypoxic patients minimize stres may require mechanical ventilation low-dose furosemide may help specific therapy if underlying cause
What is ARDS?
acute respiratory distress syndrome
pulmonary inflammatory disorder characterized by NCPE, neutrophilic inflammation, hypoxemia
What is SIRS?
systemic inflammatory response syndrome
caused by systemic inflammation of infectious or non-infectious origin
Diagnosis of SIRS in dogs and cats
2 of the 4: tachycardia tachypnea hypo or hyperthermia leukocytosis, leukopenia, or >5% bands
