Small Animal Parenchymal Disease

Question 1

describe the pulmonary parenchyma

Answer 1

parenchyma = functional substance of an organ

includes:
-alveoli
-pulmonary microvasculature
-interstitial tissues

Question 2

describe general clinical signs of pulmonary parenchymal disease

Answer 2

1. cough
2. exercise intolerance
3. tachypnea
4. excessive panting
5. increased respiratory effort to respiratory distress

not super helpful or specific!

Question 3

describe physical exam of pulm parenchymal disease

Answer 3

1. increased inspiratory and/or expiratory effort
2. increased or decreased bronchovesicular sounds
3. crackles
4. cyanosis

clinical signs can mimic airway, pleural space, and mediastinal diseases

Question 4

what is step one when you seen an animal with pulmonary parenchymal disease?

Answer 4

ALWAYS STABILIZE THE PATIENT FIRST

oxygen
anxiolysis/sedation

Question 5

define edema and pulmonary edema

Answer 5

1. abnormal fluid accumulation in tissues
2. caused by alterations in fluid flow across capillaries
   -changes in pressures, volume of flow, and/or capillary permeability
3. pulmonary edema: accumulation of serosanguinous fluid in the pulmonary interstitial space and alveoli
   -edema in extravascular space exceeds capacity of pulmonary lymphatic drainage

Question 6

what are the 3 classifications of PE

Answer 6

1. high pressure:
   -cardiogenic
   -fluid therapy
2. increased permeability:
   -ARDS
   -TRALI
3. mixed
   -negative pressure
   -neurogenic/electrocution

Question 7

describe high pressure pulmonary edema

Answer 7

cardiogenic:
-increase in pulmonary transcapillary pressure (with increase LA pressure)

non-cardiogenic:
-increased pulmonary transcapillary pressure without increased left atrial pressure

-increased vascular permeability

-or both

Question 8

describe cardiogenic pulmonary edema

Answer 8

1. most common type of pulmonary edema in vet med!
2. generally occurs gradually
3. pathogenesis:
   -left sided cardiac failure causes increased left atrial pressure
   -which causes increase in pulmonary venous pressures which leads to an increase in pulmonary capillary pressure
   -which causes leaking of fluid from the vessels into pulmonary parenchyma
4. treatment:
   -diuretics and treatment of underlying condition

Question 9

describe diagnosis of cardiogenic pulmonary edema

Answer 9

1. thoracic rads
2. echo
3. CT
4. edema fluid protein levels: compare to serum protein to see if fluid low or high protein

Question 10

what are the types of noncardiogenic pulmonary edema?

Answer 10

1. acute respiratory distress syndrome (ARDS)
2. transfusion related acute lung injury (TRALI)
3. negative pressure pulmonary edema (NPPE): also referred to as post-obstructive pulmonary edema (POPE)
4. neurogenic
5. electrocution

Question 11

describe ARDS

Answer 11

1. a clinical syndrome!
   -severe hypoxemic respiratory failure
   -severe pulmonary edema due to increase in capillary permeability
2. secondary to underlying local (pulmonary) or systemic (extrapulmonary) inflammatory process
3. causes in dogs and cats:
   -pulmonary: aspiration pneumonia, pneumonia, pulmonary contusions, chest trauma, mechanical ventilation

-non-pulmonary: sepsis, SIRS, shock, pancreatitis, trauma, AKI

Question 12

describe pathophysiology of ARDS

Answer 12

1. insult to lung (local or systemic injury)
2. acute exudative phase:
   -diffuse alveolar change
   -fluid, proteins, RBCs and WBCs leak into the alveoli activating the immune system further
   -can last from a day to a week
3. fibroproliferative phase:
   -proliferation of type II pneumoncytes
   -interstitial fibrosis
   -breathe like a pleural space patient

Question 13

describe diagnostic criteria for ARDS

Answer 13

1. timing:
   -acute onset: <72 hours
   -known risk factors
2. diagnostics:
   -thoracic rads: bilateral, diffuse pulmonary infiltrates
   -high protein edema fluid (ratio with serum protein)
3. oxygenation
   -evidence of insufficient gas exchange on blood gas analysis

Question 14

describe treatment and prognosis of ARDS

Answer 14

1. oxygen therapy: many require mechanical ventilation
2. NO evidence of improved outcome with other pharmacology agents
   -corticosteroids
   -bronchodilators
   -pulmonary vasodilators
3. BE CONSERVATIVE WITH FLUID THERAPY
4. prognosis: grave
   -survival rates around 10-20% in vet med even wit mechanical ventilation

Question 15

describe TRALI

Answer 15

1. subset of ARDS associated with transfusion of blood products
2. components of the blood product being transfused will cause neutrophils to be sequestered in the lung and initiate inflammation
3. thoracic rads: bilateral, pulmonary interstitial to alveolar infiltrates
4. treatment: oxygen therapy and supportive care

Question 16

describe negative pressure pulmonary edema causes

Answer 16

1. strangulation
2. choking
3. near-hanging
4. upper airway obstruction

Question 17

describe pathophysiology of negative pressure pulmonary edema (6)

Answer 17

1. forcible inspiration against a closed glottis
2. dramatic decrease in intrathoracic pressure
3. decrease in pulmonary interstitial hydrostatic pressure
4. increased venous return to right heart and lungs
5. both lead to increase in pressure gradient between pulmonary interstitium and vessels
6. fluid leaks from capillaries into interstitial space

Question 18

describe neurogenic pulmonary edema

Answer 18

1. post-traumatic brain injury or seizures
2. pathophysiology (mixed PE)
   -fulminant sympathetic stimulation
   -increase in systemic arterial and venous pressure
   -concurrent increase in capillary permeability
3. diagnosis:
   -thoracic rads: bilateral, diffuse interstitial to alveolar pulmonary pattern
4. treatment:
   -oxygen therapy and treatment of underlying disease
5. prognosis: good! (for the pulmonary part)

Question 19

describe electrocution

Answer 19

1. subcategory of neurogenic pulmonary edema
2. same pathophysiology as NPE (extreme sympathetic stimulation)
3. diagnosis:
   -bilateral, diffuse interstitial to alveolar infiltrates on radiographs
   -history or PE should clue you in to electrocution
4. prognosis: should be good with supportive care! (at least for the pulmonary edema part)

Question 20

describe TFAST for pulmonary edema

Answer 20

B lines/comet tails!

ultrasound version of an alveolar pattern on radiographs

normal alveoli should look uniformly like nothing, bright white lines coming down say that there is something in the alveoli besides air

Question 21

describe pulmonary hemorrhage

Answer 21

1. bleeding from any site at or below the level of the larynx
2. causes:
   -infectious causes: heartworm, lepto
   -foreign bodies, neoplasia
   -bleeding disorders (TCP, coagulopathy)

-contusions: blunt force trauma
–chest wall impact causes bursting injury to the lung
–hemorrhage and fluid exude into the parenchyma
–worsens over 24-48 hrs after injury (HBC will get worse before it gets better, takes time for bruises to develop)

6. diagnosis:
   -thoracic rads: variable and nonspecific, usually focal diffuse interstitial to alveolar pattern
   -lung ultrasound
   -CT
   -transtracheal wash vs. BAL
   -bloodwork (CBC, coags)
7. treatment and prognosis:
   -oxygen therapy
   -anxiolysis/sedation
   -treat underlying condition

-prognosis: depends on underlying condition
-hemorrhage due to contusions, foreign bodies, and pneumonia have excellent survival if discharged