Unit 1 - Pleuropneumonia

Question 1

Bacterial infections confined to the lumen of the airways are bacterial ______, while infections of the pulmonary parenchyma are called _______ (______).

Answer 1

bronchitis, pneumonia (bronchopneumonia)

Question 2

What is the primary differential for pleural effusion in the united states?

Answer 2

pleuropneumonia

Question 3

How do adult horses most commonly acquire bacterial pneumonia? Why does this occur?

Answer 3

Adult horses most commonly acquire bacterial pneumonia by aspiration of microorganisms that normally inhabit their nasopharynx or oral cavity - their immune system gets weaked at some point in some way that lets the normal flora proliferate

Question 4

What is the most common aerobic bacterial pathogen isolated from adult horses with bronchopneumonia?

Answer 4

Beta-hemolytic streptococci (Strep. equi ss zooepidemicus) is the most common.

Question 5

What other pathogens are isolated from horses with bronchopneumonia?

Answer 5

Non-enteric gram negatives including Pasteurella and Actinobacillus species are commonly found. Additionally, enteric gram negatives including Klebsiella, E. coli, Enterobacter, and Salmonella enterica have been reported with Klebsiella species having a worse prognosis.

Question 6

_____ are expected to be isolated in ⅓ of adult horses with severe pulmonary parenchymal disease.

Answer 6

Anaerobes

Question 7

What are the most common isolates of severe pulmonary parenchymal disease?

Answer 7

Bacteroides spp., Clostridium spp., Peptostreptococcus spp., Fusobacterium spp., Prevotella heparinolytica, and Eubacterium spp.

Question 8

What are the two main ways that colonization of the lungs with bacteria occurs?

Answer 8

Increased bacterial numbers: may occur following dysphagia or esophageal obstruction, transportation, head elevation, and high-intensity exercise.
Pulmonary defense compromise

Question 9

What are the endogenous pulmonary defense mechanisms?

Answer 9

mucociliar clearance, cough, respiratory or bronchial associated lymphoid tissue, and alveolar macrophages

Question 10

Identify a few factors that may reduce pulmonary defense mechanisms.

Answer 10

Stress
Viral infections
Malnutrition
Exposure to dust or noxious gases
Immunosuppressive therapy
Immunodeficiency disorders
General anesthesia 
strenuous exercise

Question 11

What does bacterial colonization and invasion result in?

Answer 11

An inflammatory response that leads to infiltration with neutrophils and other inflammatory cells into the airways (bronchitis) and pulmonary parenchyma (bronchopneumonia). Inflammatory cells and their mediators cause damage to the airway epithelium and capillary endothelium, leading to flooding of their terminal airways with inflammatory cells, serum cellular debris, and fibrin.

Question 12

True or false: lung exudation, consolidation, and abscess formation can lead to interference with gas exchange, resulting in ventilation-perfusion mismatch that causes hypoxemia.

Answer 12

TRUE

Question 13

_____ of fibrin results in reducing the spread of infection within the pleural space, but also limits the effectiveness of therapeutic pleural drainage.

Answer 13

loculation

Question 14

In what stage do fibroblasts grow into the exudate from the pleural surfaces and produce an inelastic membrane called the pleural peel (and exudate thickens)?

Answer 14

Organization stage

Question 15

What are the commonly reported clinical signs of bronchopneumonia?

Answer 15

Fever, anorexia, depression, bilateral nasal discharge, cough, weight loss, tachypnea, respiratory distress, pleural pain

Question 16

How does pleurodynia (pleural pain) manifest in equine patients?

Answer 16

Resentment to thoracic wall pain on palpation/pressure, abnormal gait/abducted elbows and reluctance to move. Ruling out abdominal pain, exertion rhabdomyolysis, and laminitis should be considered.

Question 17

What bacterial involvement is associated with halitosis and nasal discharge?

Answer 17

anaerobic

Question 18

In patients with bronchopneumonia, what do you often hear upon auscultation?

Answer 18

Tracheal rattle and adventitious lung sounds ventrally.

Question 19

What are some other potential findings in patients with bronchopneumoia?

Answer 19

Other potential findings: increase bronchial sounds, pleural friction rubs, inspiratory or expiratory crackles or wheezes, severe CrV lung consolidation or marked pleural effusion that may manifest as reduced ventral airway and/or cardiac sounds, or enhanced conduction of cardiac sounds.

Question 20

In what cases is a rebreathing examination contraindicated?

Answer 20

Suspected aspiration or dyspnea

Question 21

What are you infectious DDx for bronchopneumonia?

Answer 21

Infectious differentials include viral respiratory disease, EMPF, pulmonary aspergillosis, parasitic pneumonitis

Question 22

What are your non-infectious DDx for bronchopneumonia?

Answer 22

Non-infectious differentials include RAO (severe asthma) and IAD (mild-moderate asthma)

Question 23

What are your DDx for bronchopneumonia with pleural effusion?

Answer 23

Pleural effusion differentials include hemothorax, chest wounds, esophageal rupture, neoplasia, pericarditis, CHF, diaphragmatic hernia, severe hypoproteinemia.

Question 24

What abnormal acute phase proteins will you see in bronchitis/pneumonia cases?

Answer 24

Fibrinogen and SAA

Question 25

What is one of the most useful diagnostic procedures for bronchopneumonia?

Answer 25

Tracheobronchial Aspirate for cytology and culture

Question 26

True or false: TBA culture is preferred over thoracocentesis culture.

Answer 26

TRUE

Question 27

In bronchopneumonia cases, what cells dominate?

Answer 27

degenerate neutrophils dominate

Question 28

What pulmonary and pleural space irregularities can be viewed with thoracic ultrasonography?

Answer 28

Pulmonary irregularities include pleural thickening, comet-tail artifacts, lung tip consolidation, and focal lung consolidation / abscess formation.
Pleural space abnormalities include fluid accumulation (anechoic to echogenic fluid/debris), loculation of fibrin, pleural adhesions, pneumothorax, and pleural abscess formation.
Radiography may reveal pleural effusion, pulmonary masses, and pneumonic changes. Pleural drainage is needed prior to making thoracic radiographs when marked effusion is present.

Question 29

What condition should you consider when you see a caudodorsal pulmonary distribution radiographically?

Answer 29

Hematogenous pneumonia

Question 30

Where should you collect a thoracocentesis?

Answer 30

The most ventral aspect. Use sterile technique, local anesthetic block, and a knick skin incision. 14G catheter.

Question 31

What does normal pleural fluid look like?

Answer 31

Normal pleural fluid is transparent with a clear to pale yellow color, odorless, protein <2.5 g/dL, nucleated cell count <8K/uL.

Question 32

What does the cell count look like in pleuropneumonia pleural fluid?

Answer 32

Pleuropneumonia cases have an increased protein and cell count (>80% degenerate neutrophils).

Question 33

What does the presence of feed material in pleural fluid suggest?

Answer 33

Esophageal rupture

Question 34

How do you treat pleuropneumonia?

Answer 34

Effective antimicrobial therapy, pleural drainage, ideal supportive patient management, and in some cases surgical intervention for the removal of necrotic pulmonary foci are the hallmarks of treatment.

Question 35

What broad spectrum antimicrobials should you first consider for pleuropneumonia cases? What can provide additional Gram negative coverage? What can cover your anaerobes?

Answer 35

Beta lactams incluiding ceftiofur should be considered initially
Additional gram negative coverage can be provided with aminoglycosides.
Anaerobic coverage should be initiated in all cases - metronidazole

Question 36

When renal compromise is present, what medications should you avoid in the treatment of pleuropneumonia? What drug can you use instead?

Answer 36

aminoglycosides should be avoided - enrofloxacin can be used

Question 37

What are the benefits of using aerosolized antimicrobial agents?

Answer 37

Aerosol administration of antimicrobial agents can result in high drug concentration in the respiratory tract while minimizing systemic concentrations and their resulting toxicity.

Question 38

Identify four NSAIDs we would use in horses to minimize inflammation, provide analgesia, control fever, and provide anti-endotoxin therapy.

Answer 38

Flunixin Meglumine (banamine/prevail)
Phenylbutazone (bute)
Firocoxib (equioxx/previcox in dogs)
Meloxicam

Question 39

What can you use to prevent gastric ulcers in these cases?

Answer 39

Omeprazole

Question 40

When is it necessary to perform pleural drainage?

Answer 40

It is important for drainage of marked amounts of fluid manually to remove bacteria laden exudate, inflammatory debris, and allows for re-expansion of the lung.

Question 41

What can rapid fluid removal from the pleural space lead to?

Answer 41

Rapid fluid removal from the pleural space can lead to re-expansion pulmonary edema and hypotension.

Question 42

When is it indicated to provide intermittent or continuous pleural drainage?

Answer 42

Intermittent or continuous pleural drainage should be elected if the amount of pleural effusion increases, there is a lack of response to medical therapy, the volume of fluid results if dyspnea, evidence of anaerobic involvement (fetid odor), or there is suspicion or conformation of pleural sepsis.

Question 43

____ _____ is the act of infusing sterile, isotonic, warm fluid into the pleural space through a large bore chest tube to dilute thick, viscous pleural fluid and remove fibrin, debris, and necrotic tissue, followed by drainage through the same chest tube.

Answer 43

pleural lavage

Question 44

What must you do in the pleural space to perform a thoracoscopy?

Answer 44

Pneumothorax to allow visualization

Question 45

Describe the criteria for thoracotomy.

Answer 45

1. Failure to respond to antimicrobial therapy, pleural drainage, and pleural lavage.
2. Stable systemic medical condition. This procedure is indicated when a mature abscess has failed to respond to medical management.
3. Presence of a large amount of fibrin, debris, or exudate in the pleural space.
4. Either a walled-off lesion or presence of a complete mediastinum to avoid creation of a bilateral pneumothorax. HORSES HAVE A THIN AND DELICATE MEDIASTINUM.

Question 46

What are common complication sof pleuropneumonia?

Answer 46

Jugular vein thrombosis
Antimicrobial associated diarrhea
pneumothorax/cellulitis secondary to thoracocentesis
Coagulopathy
Pleural abscess
Bronchopleural fistula
Pericarditis
Laminitis