Diagnosis and Management of Acute Respiratory Failure

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Diagnosis and Management of Acute Respiratory
Failure
ARF 1

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Objectives

• Describe pathophysiology of acute respiratory
  failure
• Discuss diagnostic and treatment strategies

ARF 2

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Respiratory failure is common

• 360,000 cases per year in the United States
• 36 die during hospitalization
• Morbidity and mortality rates increase with age
  and presence of comorbidities

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Acute Respiratory Failure

• Hypoxemic (oxygenation)
• Room air PaO2 ? 50 mmhg
• Hypercapnic (ventilation)
• PaCO2 ? 45 mmhg
• Work of breathing

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Indication for intubation(not necessarily
respiratory failure)

• Hypoxemia
• Hypercarbia
• Work of breathing
• Cant protect airway
• Heavy secretions
• Need procedure
• Getting toxic!!

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Pathophysiology of Hypoxemia

• Ventilation/perfusion mismatch (B, C)
• Shunt physiology (A)
• Alveolar hypoventilation (nl A-a gradient)
• Decreased diffusion of O2
• High altitude (low PiO2)

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Hypoxemia
SHUNT
O2
Hypercarbia
V/Q
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Pathophysiology of Hypoxemia

• Ventilation/perfusion mismatch (B, C)
• Shunt physiology (A)
• Alveolar hypoventilation (nl A-a gradient)
• Decreased diffusion of O2
• High altitude (low PiO2)

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PAO2-PaO2 gradient

• PAO2 FiO2 (Patm - pH2O) - (1.25 x PaCO2)
• Simplistically in Denver on room air
• PAO2120- (PCO2 x 1.25)
• PaO2- from blood gas
• PAO2-PaO2 age/4

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ClearRadiographic Patterns of Hypoxemia

• Poor response to FiO2
• Shunts
• Intracardiac shunt
• Intrapulmonary shunt
• AV malformation
• Desaturated mixed venous blood- (shock)

• Good response to FiO2
• Airway obstruction
• Obesity/upper airway closure
• Asthma/obstructive lung disease
• Pulmonary embolism
• Hypoventilation

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Hypoxemia
SHUNT
O2
Hypercarbia
V/Q
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Diffuse or focal? Radiographic Patterns of
Hypoxemia (Blood, Pus or Water)

• Hydrostatic edema
• JVP, cardiac HX, S3, S4
• Bronchopneumonia
• Fever, WBC, sputum
• Aspiration
• History, mental status
• ARDS
• Precipitating cause?

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Hypercapnia

• PaCO2 VCO2 / VA
• VA RR x (Vt-Vd)
• RR, Vt, Vd
• which parameters are creating hypercarbia-Why??

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Pathophysiology of Hypercapnia

• Decreased tidal volume (Vt) and/or respiratory
  rate (RR) ?Ve
• Cant breathe
• Airways
• Parenchyma
• Pleura, chest wall, abdomen
• Muscles weak
• Wont Breathe (Drugs, OHS, CNS)

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Increased Dead Space

• Hypovolemia
• Low cardiac output
• Pulmonary embolus
• High airway pressures
• Compensate by increasing tidal volume and/or
  respiratory rate
• If unable to compensate? resp failure

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Manifestations of Respiratory Distress

• Altered mental status
• Increased work of breathing
• Tachypnea
• Accessory muscle use, retractions, paradoxical
  breathing pattern
• Catecholamine release
• Tachycardia, diaphoresis, hypertension
• Abnormal arterial blood gas values

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Principles of management

• Identify problem
• oxygen? ventilation? Work of breathing?
• Supplemental oxygen?
• Assist in ventilation?
• Reduce work of breathing?
• Identify etiology
• Assess reversibility

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Acute Respiratory Failure Management

• Oxygen supplementation
• Increase FIO2
• Match flow between delivery device and
  inspiratory demand

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Nasal Cannula

• 100 oxygen delivered
• Low flow
• lt0.55.0 L/min
• Low oxygen
• FIO2 lt0.40.5

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Reservoir Face Mask

• Reservoir bag filled with 100 O2
• High oxygen
• High flow

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Resuscitation Bag-Mask-Valve Device

• 100 O2
• High flow (gt 15 L/min)
• Emergency equipment
• Little to no air entrainment with firm fit

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Pharmacologic Adjuncts

• Bronchodilators
• ?2-agonists
• Anticholinergics
• Corticosteroids
• Lasix/Vasodilators
• Antibiotics
• Anticoagulation or thrombolysis

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An approach

• ? Hypoxemia and/or hypoventilation
• Need ABG, Use SPO2
• ? A-a gradient
• ? Response to 100 FiO2
• ? CXR clear or white
• ? Work of Breathing
• ? Etiology? treatment

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7.32/50/48 (SPO2-83)
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7.45/33/52 SPO2-87
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7.28/60/45 on RA (SPO2-80)
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7.48/30/56 (SPO2-89)
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7.48/30/46 (SPO2-83)
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THE END