Page 115 - Critical Care Notes

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■ Increased pressure to ventilate
■ Hypoxemia refractory to increased fractional concentration of oxygen in
inspired gas (FIO 2 )
■ Increased peak inspiratory pressure
· ·
■ Decreased lung volume, decreased functional residual capacity, low V/Q ratio
■ PCWP <18 mm Hg and/or no evidence of HF or left atrial hypertension
■ Acute respiratory alkalosis initially, which may progress to respiratory acidosis
■ Worsening ABGs with increased FIO 2 , leading to marked hypoxemia,
increased crackles
■ Worsening PaO 2 /FIO 2 ratio (P/F ratio)
■ Increase in A-a gradient (difference between alveolar and arterial oxygen
tension = normal value of <15 mm Hg)
■ Diffuse bilateral pulmonary infiltrates on CXR indicating “whiteout”
■ Fluid and electrolyte problems
■ Tachycardia and arrhythmias, especially PVCs
■ Labile blood pressure, hypotension
■ Decreased gut motility
■ Generalized edema with poor skin integrity and skin breakdown
■ Symptoms of impaired coagulation
■ Can lead to sepsis and ventilator-associated pneumonia after intubation
Diagnostic Tests
■ ABGs and venous blood gases
■ Mixed venous oxygen saturation
■ Continuous oxygenation monitoring via pulse oximetry
■ Pulmonary function tests
■ Intrapulmonary shunt fraction is the ratio; PaO 2 to FIO 2 ratio (P/F ratio) of
<200 mm Hg indicative of ARDS
■ P/F ratio >300 considered normal
■ P/F ratio >200 indicative of a 15%–20% intrapulmonary shunt
■ P/F ratio >100 indicative of an intrapulmonary shunt >20%
■ Pulmonary artery catheter
■ Serial CXRs
■ Chest CT
■ ECG and echocardiogram
■ CBC, metabolic panel, serum lactate (lactic acid)
■ Plasma brain (B-type) natriuretic peptide (BNP) levels
Management
■ Treat underlying cause.
■ Administer antibiotics if infection suspected.
■ Assess respiratory, cardiac, and neurological status frequently.
■ Administer O 2 mask or mechanical ventilation with positive end-expiratory
pressure (PEEP) and high FIO 2 . Consider high-frequency oscillation ventilation
(HFOV)—used when difficulty oxygenating a patient on conventional setting
because of poor lung compliance (required neuromuscular blockade).
RESP