ARDS: Diagnosis and Symptoms

• ARDS is a life-threatening lung condition that impairs lung function and requires lifestyle changes.
• Optimum patient function necessitates a comprehensive interprofessional team approach.

Assessment

• Signs and symptoms are nonspecific: acute dyspnea, tachypnea, and hypoxemia.
• Assess breathing for increased work: hyperpnea, noisy respiration, cyanosis, pallor/ash gray skin, and retractions.
• Document sweating, respiratory effort, and mental status changes.
• Lung sounds may be normal because edema occurs in interstitial spaces, not airways.
• Monitor vital signs hourly for hypotension, tachycardia, and dysrhythmias.
• No single test diagnoses ARDS; diagnosis is based on clinical picture, symptoms, physical exam, lab tests, and chest imaging.
• Diagnosis criterion: respiratory symptoms onset within 1 week of a clinical insult.
• Arterial blood gas often reveals lowered partial pressure of arterial oxygen (Pao₂), signifying decreased gas exchange.
• Widening alveolar oxygen gradient and increased shunting necessitate higher oxygen levels.
• P/F ratio (Pao₂ divided by Fio₂) assesses ARDS severity.
• P/F ratio >200 but ≤300 mm Hg indicates mild ARDS.
• P/F ratio >100 mm Hg but ≤200 mm Hg indicates moderate ARDS.
• P/F ratio ≤100 mg Hg indicates severe ARDS.
• Other labs: complete blood count, metabolic panel, coagulation studies, D-dimer, troponin, lactate, brain natriuretic peptide, lipase, and cultures.
• Sputum cultures (obtained by bronchoscopy) check for lung infection.
• Chest x-ray displays diffused haziness or a ground-glass appearance in the lungs.
• ECG rules out cardiac problems.

Interventions

• Management focuses on the three phases; timing varies by patient.

Exudative Phase

• Early dyspnea and tachypnea result from fluid-filled alveoli, pulmonary shunting, and atelectasis.
• Early interventions support the patient and provide oxygen.

Fibrosing Alveolitis Phase

• Lung injury causes pulmonary hypertension and fibrosis.
• The body attempts to repair damage, but increased lung involvement reduces gas exchange.
• MODS can occur.
• Interventions involve delivering oxygen, preventing complications, and supporting the lungs.

Resolution Phase

• Begins after 14 days; complete resolution is possible, but if not, death/chronic disease occurs.
• Fibrosis may or may not occur.
• Survivors may have neuropsychological deficits.

Specific Management

• Intubation and mechanical ventilation with PEEP or CPAP are often needed.
• "Open lung" and lung-protective strategies are best.
• Low tidal volumes (6 mL/kg) prevent lung injury.
• PEEP starts at 5 cm H2O, increased to maintain adequate oxygen saturation; levels may need to be high.
• Pressure-controlled ventilation is preferred to promote gas exchange in nonfunctional alveoli.
• Tension pneumothorax is a risk with PEEP.
• Assess lung sounds hourly, suction as needed to maintain an open airway.
• APRV and HFOV improve gas exchange for moderate to severe ARDS.
• APRV and HFOV use significantly higher airway pressure
• Sedation and paralysis may be needed for HFOV but may not be needed for APRV; reduces tissue oxygen needs.
• APRV allows spontaneous breathing between mandatory breaths.
• Positioning promotes gas exchange.
• Prone positioning, especially if initiated early, reduces mortality in moderate to severe ARDS.
• Prone positioning can be done manually or with a mechanical turning device.
• Automated kinetic beds help with turning.
• No set timing/duration exists for prone positioning.
• Early in clinical course, at least 12 hours a day is recommended if there are no contraindications.
• Prone positioning requires coordinated effort from at least four people.
• Risks include dislodgment of lines/tubes, airway obstruction, pressure injuries, trauma, hypotension, arrhythmia, brachial plexus injury.
• Avoid prone positioning in patients with acute bleeding, elevated intracranial pressure, or unstable fractures.
• Manual turning every 2 hours improves perfusion, regardless of position.
• Early progressive mobility reduces ventilator needs, days on ventilator, and mortality.
• Automatic turning slightly decreases pulmonary complications, but no clear benefits for length of stay.

Oxygenation

• ECMO is a life-support technique for severe ARDS with refractory hypoxemia.
• Proper timing and standardization of ECMO are not established.
• Survival is more likely in younger patients without other health problems.
• ECMO may not be available at many community hospitals.

Drug and Fluid Therapy

• No treatments reverse lung pathology.
• Treatment focuses on supportive care: oxygenation, decreased oxygen consumption, prevention of complications, fluid therapy, and treating underlying conditions.
• Treat underlying condition, for example, antibiotics for sepsis.
• Decreasing oxygen consumption includes treating fever, pain, anxiety, and respiratory muscle effort.
• Conservative fluid therapy improves lung function, shortens ventilation and ICU stay.
• Liberal fluid therapy can result in edema.
• Slight hypotension may help prevent ARDS in trauma patients.

Nutrition Therapy

• Patients are at risk for malnutrition
• Nutrition support is needed to support respiratory muscle function and immune response.
• Enteral or parenteral nutrition should begin as soon as possible.

Severe COVID-19

• Hypoxemia (oxygen saturation 94% or less on room air) is a sign
• Oxygen or ventilatory support is needed
• Risk factors: increasing age, male gender, comorbidities.
• Comorbidities: cancer, stroke, kidney/lung/liver disease, diabetes, heart disease, HIV, pregnancy, mental health disorders, substance use, smoking, and BMI over 25.
• Genetic/social factors also increase risk.

Assessment

• Dyspnea followed by hypoxemia.
• Symptoms of severe viral pneumonia: respiratory rate above 30, lung infiltrates, and oxygen saturation of 94% or less.
• Can progress to critical illness (multiple organ failure).
• Critical illness marked by respiratory failure, septic shock, and/or multiorgan failure.
• Acute respiratory failure often is a result of ARDS.
• Complications of ARDS can cause worsening of respiratory failure.
• COVID-19 may cause pulmonary embolism, pleural effusion, or pneumothorax.
• Complications: thromboembolic events, kidney/myocardial injury, liver enzyme elevation, encephalopathy, cholecystitis, ileus, pancreatitis.
• Rare MIS-A syndrome with elevated inflammatory markers, absence of symptoms, and severe dysfunction.
• Other complications: malnutrition, blood clots, pressure ulcers; many need rehabilitation.
• Lab abnormalities: elevated D-dimer, CRP, LDH, troponin, ferritin; changes in platelets.
• Blood gas values are also abnormal.

Interventions

• Management combines severe/critical care with non-COVID-19 ARDS protocols.
• Includes supportive care, lung protection, and treatment of underlying medical conditions and complications.

Mechanical Ventilation

• Timing of intubation needs to be handled on a case-by-case basis.
• HFNC is typically preferred over NPPV unless specific indications exits (ex: hypercapnia).
• Oxygenation goals typically range from 92% - 96%. Some clinicians accept 88% - 90%.
• If certain criteria are met, NPPV can be trialed to potentially prevent intubation.
• Early intubation may decrease self-inflicted lung injury.
• Delaying intubation may lead to clinical deterioration/emergent intubation.

Minimize Aerosolization

• Minimize aerosol-generating procedures such as bronchoscopy, sputum induction, oral and airway suctioning and manual ventilation with BVM.
• Perform procedures in negative pressure room.
• Use PPE.
• Metered-dose inhaler is preferred over nebulizers.

Drug Therapies

• Glucocorticoids and Remdesivir or Baricitinib, can reduce mortality.
• These therapies ordered according to symptoms, severity, oxygen, labs, availability, and protocol.

Positioning

• Prone positioning improves oxygenation, can be use for intubated and non-intubated patients (awake pronation).
• Must be no contraindications.
• Pronation may prevent intubation.
• Prone positioning entails 6-8 hours in 24-hour period.
• Options: left lateral decubitus or fully prone position.

Communication Challenges

• Precautions can cause anxiety.
• Interventions: place phone/call lights next to patient, encourage distractions, encourage video communication.

Planning

• Advance planning and goals of care should occur on admission.
• Meetings should be held to update on patient's condition.

Mechanical Ventilation

• The goal of intubation is to maintain a patient airway, remove secretions, and proved oxygen.
• ET tube inserted through the mouth of nose, resting 2cm above the carina.
• Anesthesiologists, nurses, RTs or other trained personnel can do the intubation.
• Patients must wear necessary PPE.
• X-ray helps determine proper place.
• Distal cuff of tube is inflated to ensure the tube effectively seals, delivering the tidal volume when mechanically ventilated.
• Pilot balloon used to determine if air pressure is adequate.
• 7-9mm tube sizes typically used for adults.
• Staff members must know how to summon intubation staff if it is necessary.
• BVM helps guarantee survival during medical intervention.
• Monitor patients who are at increased risk for ventilation failure.
• During the process the code or crash cart, equipment and suction should be available.
• The staff and patient can facilitate a patent airway.
• Immediately after ET tube placement staff members will check the end-tidal carbon dioxide and chest x-ray.
• Breath sounds, chest movement, and presence of air are observed.
• Healthcare provide must reposition tube if needed.
• If it is in the stomach, the abdomen will be extended.
• Health providers secure tube at mouth or nose level and mark accordingly.
• Two people are needed for this process.
• The nurse who is caring for the person must maintain a patent airway, assess breath sounds and the pressure of the tube.