GMED3009- Respiratory failure (ARDS) Flashcards
Definition of acute respiratory distress syndrome (ARDS)
acute, diffuse, inflammatory form of lung injury that is associated with a variety of etiologies. characterised by noncardiogenic pulmonary oedema and severe refractory hypoxaemia
What conditions are associated with direct and indirect lung injury?
direct= penumonia, aspiration of gastric contents, pulmonary contusion, fat emboli, inhalation injury, near drowning, reperfusion pulmonary edema
Indirect- sepsis, multiple trauma, multiple blood transfusions, cardiopulmonary bypass, burns, acute pancreatitis,drug overdose
Pathophysiology of ARDS
- It is unregulated systemic inflammatory response to acute injury or inflammation
- Inflammatory cellular responses and biochemical mediators damage the alveolar-capillary membrane
- In response to direct lung injury or a systemic insult such as endotoxin, an increase in pulmonary or circulatory pro- inflammatory cytokines occurs.
- Activated neutrophils secrete cytokines, such as tumour necrosis factor-alpha and interleukins, which increase the inflammatory response
- Neutrophils also produce oxygen radicals and proteases that can injure the capillary endothelium and alveolar epithelium
- Epithelial and endothelial damage, in turn, leads to increased permeability and the subsequent influx of protein-rich fluid into the alveolar space. In addition to these structural changes, there is evidence of impaired fibrinolysis in ARDS that leads to capillary thrombosis and microinfarction.
- Some patients achieve complete resolution of lung injury before progressing into the fibroproliferative stage, whereas others progress directly to develop fibrosis.
- The extent of fibrosis may be determined by the severity of the initial injury, toxic oxygen effects, and ventilator-associated lung injury
Definition of respiratory failure
Respiratory failure is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, it may be classified as either hypoxemic or hypercapnic
Types of respiratory failure
1) Hypoxemic respiratory failure (type I)= is characterized by Pa O2 <60 mm Hg with a normal or low Pa CO2. This is the most common form of respiratory failure, and it can be associated with virtually all acute diseases of the lung, which generally involve fluid filling or collapse of alveolar units. Some examples of type I respiratory failure are cardiogenic or noncardiogenic pulmonary oedema, pneumonia, and pulmonary hemorrhage.
2) Hypercapnic respiratory failure (type II) is characterized by a PaCO2 > 50 mm Hg. Hypoxemia is common in patients with hypercapnic respiratory failure who are breathing room air. The pH depends on the level of bicarbonate, which, in turn, is dependent on the duration of hypercapnia. Common aetiologies include drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders (eg, asthma and COPD).
Common causes of type I (hypoxemic) respiratory failure
● COPD
● Pneumonia
● Pulmonary edema
● Pulmonary fibrosis
● Asthma
● Pneumothorax
● Pulmonary embolism
● Pulmonary arterial hypertension
● Pneumoconiosis
● Granulomatous lung diseases
● Cyanotic congenital heart disease
● Bronchiectasis
● Acute respiratory distress syndrome (ARDS)
● Fat embolism syndrome
Common causes of type 2 (hypercapnic) respiratory failure
● COPD
● Severe asthma
● Drug overdose
● Poisonings
● Myasthenia gravis
● Primary muscle disorders
● Cervical cordotomy
● Head and cervical cord injury
● Pulmonary edema
● ARDS
● Myxedema
● Tetanus
Describe the typical signs and symptoms of Respiratory Failure
Type 1 RF: Dyspnoea, Tachypnoea, Use of accessory muscle, decreased SaO2
Type 2 RF: Dypnoea, ^RR with shallow respirations, decreased tidal volume and decreased minute ventilation
Describe the typical signs and symptoms of Respiratory Failure
Type 1 RF: Dyspnoea, Tachypnoea, Use of accessory muscle, decreased SaO2
Type 2 RF: Dypnoea, ^RR with shallow respirations, decreased tidal volume and decreased minute ventilation
Discuss the clinical and physical assessment of a patient with Respiratory Failure
RESP: Tachypnea slowly progressing to bradypnoea. Shallow breathing, use of accessory muscles, Dyspnoea
CNS: General agitation due to hypoxia, restlessness, fluctuating GCS depending on PaCO2 levels. Confusion, delirium, tremors, siezures
CVS: Tachycardia progressing to bradycardia. Arrhythmias (from the acidosis), bounding pulse, hypertension progressing to hypotension, JVP distended. Cyanosis, a bluish color of skin and mucous membranes, indicates hypoxemia.
What diagnostic studies would be performed on a patient with Respiratory failure?
CXR
Discuss the specific routine nursing care of a patient with respiratory failure
● Main goals of care for RF include ensuring adequate oxygenation and ventilation. Ensure that oxygen delivery device is appropriate administering for administering supplemental oxygen.
● Oxygen therapy may require humidification to aid in loosening secretions. Thick secretions are hard to expel
● Adequate fluid intake- to maintain hydration status, also helps in keeping the secretions thin and easier to remove
● Chest physio- assists with secretion removal and positioning to help improve oxygenation. Postural draining may also assist secretion removal
● Airway suctioning- if the patient is unable to expel own secretions.
● Encourage adequate nutritional support- The hypermetabolic state in critical illness increases the energy requirements therefore increase in nutritional support is required to maintain body weight and muscle mass
● Encourage deep breathing and coughing to prevent obstruction caused by secretions
● Position patient in upright position at 45 degrees to help maximize chest expansion
Discuss common complications of Respiratory failure
Common cardiovascular complications in patients with acute respiratory failure include hypotension, reduced cardiac output, arrhythmia, pericarditis, and acute myocardial infarction. These complications may be related to the underlying disease process, mechanical ventilation, or the use of pulmonary artery catheters.
Hospital acquired infections, such as pneumonia, urinary tract infections, and catheter-related sepsis, are frequent complications of acute respiratory failure. These usually occur with the use of mechanical devices. The incidence of nosocomial pneumonia is high and associated with significant mortality.
Pharmological treatment
Salbuatmol
Ipratropium
Aetiology of ARDS
acute condition characterised by bilateral pulmonary infiltrates. Cardiogenic pulmonary edema must be excluded, severe hypoxemia in the absence of evidence for cardiogenic pulmonary edema.
