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Acute Respiratory Distress Syndrome 27

Technician Tips may be quite extensive once the matted hair SUGGESTED READING
These lesions can be among the most painful is removed. Clipping the coat short in long- Holm BR, et al: A prospective study of clinical
VetBooks.ir pain by ensuring that antiseptic lavage solutions warm weather months reduces the potential of pyotraumatic dermatitis. Vet Dermatol Diseases and Disorders
haired breeds that swim frequently during the
of any seen in practice. Be sure to minimize
findings, treatment and histopathology of 44 cases
15(6):369–376, 2004.
are at body temperature before use and that
for acute moist dermatitis. Investigating and
clipper blades do not overheat if hair clipping
is critical to reduce/prevent recurrent acute
is extensive. controlling or eliminating the underlying disease AUTHOR: Jocelyn Wellington, DVM, DACVD
EDITOR: Manon Paradis, DMV, MVSc, DACVD
moist dermatitis.
Client Education
To minimize the owner’s shock, inform clients
on the patient’s admission that the erosive lesion
Acute Respiratory Distress Syndrome Client Education
Sheet

BASIC INFORMATION • Pulmonary ARDS may develop as a result actual time course for each stage in dogs is
of a direct pulmonary insult such as pneu- not known. However, the clinician should
Definition monia or pulmonary contusion. anticipate that recovery from ARDS requires
Acute respiratory distress syndrome (ARDS) • Extrapulmonary ARDS may develop in a weeks.
refers to the development of noncardiogenic critically ill or injured dog as part of the • ARDS in people is considered a clinical
pulmonary edema as an inflammatory response multiple organ dysfunction syndrome when diagnosis not requiring histopathology. The
to severe illness or injury. the initial insult was outside the lung (e.g., criteria for diagnosis include
septic abdomen). ○ Underlying event (e.g., severe trauma/
Synonyms • A short-term ARDS-like syndrome that sepsis)
Adult respiratory distress syndrome, ARDS, develops after blood transfusion is recog- ○ Diffuse bilateral pulmonary infiltrates on
shock lung nized in human medicine as transfusion- thoracic radiographs
related acute lung injury (TRALI, ○ Hypoxemia (PaO 2 /FIO 2 ratio of < 300)
Epidemiology p. 989). ○ Decreased pulmonary compliance (stiff
SPECIES, AGE, SEX lungs)
Any critically ill dog may be affected; it is HISTORY, CHIEF COMPLAINT ○ Absence of heart failure (normal pulmo-
unclear if cats can develop ARDS. • Reflects the initial presenting complaint; nary capillary wedge pressure)
while hospitalized, the dog does not improve • Equivalent criteria have not been validated
RISK FACTORS as predicted or develops progressive tachy- for veterinary patients.
Severe critical illness or injury pnea and respiratory distress over hours to
days. DIAGNOSIS
ASSOCIATED DISORDERS • ARDS usually is a condition that develops
Although ARDS may be associated with other in hospitalized dogs. Diagnostic Overview
disorders, common associations include sepsis ARDS usually is a composite diagnosis.
and septic shock, polytrauma, neoplasia, and PHYSICAL EXAM FINDINGS Dyspnea in a systemically ill or traumatized
pancreatitis. Exam findings reflect ARDS and the underlying patient with pulmonary interstitial to alveolar
insult or nonrespiratory complications of the markings on thoracic radiographs, when
Clinical Presentation insult (e.g., evidence of polytrauma; petechial congestive heart failure, pulmonary thrombo-
DISEASE FORMS/SUBTYPES hemorrhage due to sepsis-related disseminated embolism (PTE), and pneumonia are effectively
• ARDS may be classified as mild, moderate, intravascular coagulation). ruled out as the sole issue, have a working
or severe. Broadly, all types of ARDS rep- • Increased respiratory rate and effort diagnosis of ARDS. Benefits of diagnostic
resent lung injury occurring within 1 week • Loud bronchovesicular sounds or crackles testing must be weighed against risks, and the
of a clinical insult, with progression to on thoracic auscultation certainty of diagnosis may be established only
respiratory distress. Bilateral pulmonary • Orthopnea retrospectively with response to treatment or
infiltrates must be demonstrated by thoracic • Cyanosis if advanced histopathology.
imaging (computed tomography [CT] or
radiographs), without evidence of heart Etiology and Pathophysiology Differential Diagnosis
failure. Hypoxemia, when being supported • A pulmonary or extrapulmonary insult results • Pneumonia
by at least 5 cm H 2 O positive end-expiratory in severe systemic inflammation. • Volume overload or congestive heart failure/
pressure (PEEP), must be present. • Cytokines and other proinflammatory cardiogenic pulmonary edema
• In human medicine, an ARDS definition products cause vasculitis, and when diffuse • PTE
task force developed a set of Berlin defini- alveolar damage occurs, a protein-rich
tions; these replaced the term acute lung noncardiogenic pulmonary edema is the Initial Database
injury with the term mild ARDS. Subtyping result. Thoracic radiographs to identify infiltrates
is less well defined in veterinary medicine. • Pulmonary edema results in ventilation- and exclude other causes of respiratory
A PaO 2/FIO 2 ratio characterizes ARDS as perfusion (V-Q) mismatch and severe distress
○ Mild ARDS: 201-300 mm Hg (≤ 39.9 kPa) hypoxemia. • Cardiogenic pulmonary edema typically
○ Moderate ARDS: 101-200 mm Hg • Three stages of ARDS have been described: predominates in a perihilar and right caudal
(≤ 26.6 kPa) exudative, proliferative, and fibrotic. Surviving pulmonary distribution, but when severe, it
○ Severe ARDS: ≤ 100 mm Hg (≤ 13.3 kPa) patients proceed through each stage. The may not be clearly regional (p. 408).

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