ARDS Definition
A diffuse, heterogonous inflammatory response of the lungs, resulting in hypoxemia, consolidation, and a decrease in compliance
There will be the presence of bilateral pulmonary infiltrates in all regions of the lung
How Does ARDS tend to be diagnosed
ARDS tends to be a diagnosis based on the exclusion of other possible causes of acute hypoxemia respiratory failure with bilateral alveolar infiltrates
What is the main differential diagnosis that needs to be ruled out when disganosing ARDS
Cardiogenic pulmonary edema is the primary differential diagnosis that needs to be ruled out
What Are Some Differentil Diagnosis for ARDS
Cardiogenic Pulmonary Edema
Diffused alveolar hemorrhage
Idiopathic acute exacerbation of pre-existing interstitial lung disease
Acute eosinophilic pneumonia
Cryptogenic organizing pneumonia
Acute Interstitial pneumonia
Rapidly disseminating cancer
ARDS Onset
There will be a sudden and acute onset of the disease
Rapid decline in 24-72 hours
Pulmonary Wedge Pressure in ARDS
Before this was used to help differentiate between cardiac and respiratory problems, now clinicians tend to reply more on the patient history
If there is a need to determine if there is a cardiac component clinicians tend to now use an ECHO rather than get a PAWP
Hypoxemic Respirtory Failure and ARDS
Hypoxemic respiratory failure will occur regardless of etiology due to the damage to the alveolar/capillary membrane
Because this is a hallmark of ARDS it is important that if you have a patient who is quickly desating and is refractory to oxygen therapy to let the doctor know and consider intubation soon in a controlled environment
Severe hypoxemia
P/F Ratio <200 mmHg regardless of PEEP or FiO2 level
What is the severity of ARDS based on according to the Berlin Definition
The severity of the hypoxemia defines the severity of the ARDS
Berlin Definition of ARDS
The Berlin Definition of ARDS is used for diagnostic criteria for ARDS and requires all of the following elements to be met
- Respiratory symptons occur within 1 week of known clinical event OR new or worsening symptons occur over the course of a week
- Bilateral opacities on chest xray or CT, that are not explained by another disease
- Respiratory failure is not the cause of hert failure or fluid overload
- Moderate to severe oxygenation problem are present (P/F Ratio)
The bilateral opacies on the chest xray are similar to what
Pulmonary Edema
When you see bilateral opacies on the chest xray what other diseases process should you make sure to rule our
The opacities should not be explained by pleural effusion, lobar or lung collapse, or pulmonary nodules.
To ensure that respiratory failure is not the cause of hert failure or fluid overload what should you do
An objective assessment to rule out hydrostatic pulmonary edema is required if risk factors are not present for ARDS (e.g., echocardiography).
Berlin Definition of Mild ARDS
The PaO2/FIO2 is >200 mm Hg, but ≤300 mm Hg, on ventilator settings that include positive end- expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥5 cm H2O.
Berlin Definition of Moderate ARDS
The PaO2/FIO2 is >100 mm Hg, but ≤200 mm Hg, on ventilator settings that include PEEP ≥5 cm H2O
Berlin Definition of Severe ARDS
The PaO2/FIO2 is ≤100 mm Hg on ventilator settings that include PEEP ≥5 cm H2O
Acute Hypoxemic Respiratory Failure
severe arterial hypoxemia that is refractory to supplemental oxygen.
It is caused by intrapulmonary shunting of blood resulting from airspace filling or collapse.
Findings include dyspnea and tachypnea.
Diagnosis is by ABGs and chest x-ray.
Treatment usually requires mechanical ventilation.