ARDS & COVID-19
RESTRICTIVE LUNG CONDITIONS
Presentation by: Becca Pham, PT, DPT, CCS
Focus: ARDS & COVID-19
GUIDING QUESTIONS
Definitions and Analysis:
What is ARDS?
Acute Respiratory Distress Syndrome (ARDS) is a severe lung condition resulting from various direct or indirect injuries, causing extensive inflammation, alveolar damage, and significant respiratory failure.
How does it lead to respiratory failure?
ARDS leads to respiratory failure through mechanisms such as increased permeability of the alveolar-capillary membrane, causing pulmonary edema, impaired gas exchange, and reduced lung compliance.
Triggers for ARDS?
Triggers include pneumonia, traumatic injuries, sepsis, aspiration of stomach contents, inhalation of toxic fumes, and COVID-19.
Stages of ARDS?
ARDS progresses through stages:
Exudative phase characterized by inflammatory cell infiltration and vascular leakage.
Proliferative phase with attempts at lung repair but ongoing inflammation.
Fibrotic phase leading to scarring and potential chronic lung dysfunction.
Clinical features in ARDS (signs, symptoms, lab findings, diagnostic tests)?
Symptoms include severe dyspnea, hypoxemia, and mental status changes.
Signs include retraction of intercostal muscles, tachypnea, and cyanosis.
Labs reveal decreased PaO2 and elevated inflammatory markers. Diagnostic tests include chest X-ray showing ground glass opacities initially and later potential fibrosis.
COVID-19 relevance to ARDS?
COVID-19, caused by the SARS-CoV-2 virus, can trigger ARDS through a hyper-inflammatory response, leading to severe pulmonary injury and the need for aggressive management.
Severity distinctions for COVID-19 symptoms?
Symptoms vary from mild (dry cough and fever) to moderate/severe with significant respiratory involvement, leading to hospitalization or critical care settings.
Cardiac system impacts from COVID-19?
COVID-19 poses risks of cardiac injury, arrhythmias, and exacerbation of pre-existing cardiovascular diseases through mechanisms such as hypoxia and inflammation.
Cardiac manifestations?
Manifestations can include myocarditis, heart failure, and myocardial infarction due to increased strain on the heart and systemic inflammation.
Reasons for mechanical ventilation in ARDS?
Indications encompass persistent hypoxemia, increased work of breathing, and respiratory muscle fatigue, necessitating support to maintain adequate oxygenation and ventilation.
Benefits of prone positioning for critically ill patients?
Prone positioning can improve lung recruitment, enhance oxygenation, and decrease ventilator-induced lung injury.
Indicators for prone positioning?
Indications include severe hypoxemia (PaO2/FiO2 ratio <150) and patient stability to tolerate the position.
Advantages and disadvantages of prone positioning?
Advantages: Improved ventilation-perfusion matching, reduced shunting, enhanced lung volume.
Disadvantages: Potential for skin injury, airway management challenges, and logistical issues in critical care settings.
What is ECMO and the two types?
Extracorporeal Membrane Oxygenation (ECMO) is a technique that provides cardiac and respiratory support to patients whose heart and lungs are unable to function adequately. Types include:
VA-ECMO: Provides both respiratory and hemodynamic support.
VV-ECMO: Provides lung support only, typically for patients with severe respiratory failure.
Goals for PT in early vs. late ARDS stages.
Early goals focus on improving lung function and mobility, preventing contractures, and facilitating airway clearance.
Late goals involve advanced rehabilitation, strength training, aerobic conditioning, and functional independence recovery.
ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)
Description:
ARDS is characterized by rapid onset of widespread inflammation and alveolar damage leading to severe respiratory distress, hypoxemia, decreased lung compliance, and potential multi-organ dysfunction due to impaired gas exchange.
RESTRICTIVE LUNG ETIOLOGY
Causes Within the Lung (Intrapulmonary):
Interstitial lung disease
Pneumonia
Pulmonary edema/ARDS
Causes Outside the Lung (Extrapulmonary):
Diseases affecting the pleura (e.g., pleuritis)
Disorders of chest wall (e.g., scoliosis, kyphosis)
Extra thoracic issues (e.g., obesity)
Impaired respiratory drive due to neurological disorders (e.g., traumatic brain injury)
Neurological and neuromuscular disorders (e.g., spinal cord injury, ALS)
Musculoskeletal problems affecting respiratory mechanics.
ADULT RESPIRATORY DISTRESS SYNDROME (ARDS)
Definition:
Non-cardiogenic pulmonary edema due to an exaggerated inflammatory response as a consequence of lung injury. This leads to diffuse alveolar injury and increased capillary permeability resulting in hypoxemic respiratory failure.
ETIOLOGY OF ARDS
Direct Causes:
Lung infections (e.g., pneumonia, COVID-19)
Chest trauma
Aspiration of food, fluids, or vomitus
Inhalation of toxic substances (e.g., smoke, chemicals)
Near drowning incidents.
Indirect Causes:
Shock of various etiologies
Sepsis leading to multiorgan failure
Severe trauma resulting in systemic inflammatory response syndrome (SIRS)
Substance overdose (particularly narcotics and sedatives).
STAGES OF ARDS
Early ARDS (Exudative):
Characterized by intense acute inflammatory response, increased capillary permeability, resulting in a "wet" lung appearance on imaging.
High potential for hypoxemia and pulmonary hypertension.
Late ARDS:
Proliferative Phase: Attempts at repair occur; alveolar epithelium is disrupted along with persistent inflammation.
Fibrotic Phase: Results in significant and sometimes irreversible lung scarring, impairment of lung function, and risk of chronic respiratory failure.
CLINICAL MANIFESTATIONS OF ARDS
Symptoms:
Severe dyspnea at rest and exacerbated during activity
Rapid, labored breathing
Cyanosis indicating severe oxygen deprivation
Impaired mental status due to hypoxia
Agitation/restlessness due to distress and impaired gas exchange.
Signs:
Increased work of breathing (use of accessory muscles)
Rapid respiratory rate (tachypnea)
Retraction of intercostal muscles during breaths
Auscultation may reveal abnormal breath sounds (fine crackles, coarse crackles).
LAB FINDINGS
ABG Analysis:
Decreased arterial PaO2, often accompanied by refractory hypoxemia (PaO2 < 60 mmHg despite high oxygen concentration on any FiO2).
P:F Ratio:
Classification:
Mild: 200-300
Moderate: 100-199
Severe: <100 (indicating progression of ARDS and severity of hypoxemia).
Inflammatory Markers:
Elevated levels of C-reactive protein and pro-inflammatory cytokines.
DIAGNOSTIC TESTS
Pulmonary Function Tests: Typically show decreased vital capacity (VC), tidal volume (VT), functional residual capacity (FRC), and decreased diffusing capacity for carbon monoxide (DLCO)
Chest X-ray Findings:
Early Stage: Fluffy infiltrates indicating ground-glass opacities.
Late Stage: Potentially clear alveolar fluid but with signs of scarring or fibrosis developing.
COVID-19
Introduction:
COVID-19 induction of pulmonary edema is primarily due to the SARS-CoV-2 virus, leading directly to ARDS. The virus is highly contagious and is primarily spread through respiratory droplets.
COVID-19 SYMPTOMS & SEVERITY:
Most Patients (80-90%): Experience mild illness characterized by dry cough, fever, and fatigue.
Moderate, Severe, and Critical Cases: Require close monitoring of oxygen saturation levels and any emerging lung infiltrates.
Long COVID: Some individuals experience prolonged symptoms even after recovery from the acute phase of the illness, leading to chronic complications.
CARDIAC MANIFESTATIONS OF COVID-19
Mechanisms of Injury:
Increased cardiac stress secondary to respiratory failure and resultant hypoxemia. There is also a potential for direct myocardial infection, leading to serious cardiovascular events.