Lung pathology in the ICU Flashcards
What is Type 1 respiratory failure?
Type 1 respiratory failure occurs when the respiratory system cannot adequately provide oxygen to the body, leading to hypoxemia. It can be caused by alveolar hypoventilation, low atmospheric pressure, diffusion defect, ventilation/perfusion mismatch, or right-to-left shunt.
What are the typical lab findings in Type 1 respiratory failure?
Partial pressure of oxygen (PaO2) is less than 60 mmHg with normal or decreased partial pressure of carbon dioxide (PaCO2). The alveolar-arterial (A-a) gradient may be normal or increased.
What causes Type 2 respiratory failure?
Type 2 respiratory failure is caused by the inability of the respiratory system to remove carbon dioxide, leading to hypercapnia. This can be due to respiratory pump failure or increased carbon dioxide production.
What are the clinical indicators of Type 2 respiratory failure?
Arterial CO2 (PaCO2) is greater than 45 mmHg, and pH is less than 7.35.
What is aspiration pneumonitis, and what can it lead to if untreated?
Aspiration pneumonitis is the inhalation of gastric fluid with a pH of less than 2.5, which can lead to chemical pneumonitis. Untreated, it can progress to acute respiratory distress syndrome (ARDS).
What are the causes of atelectasis?
Atelectasis can be caused by compressive, resorptive (obstructive), or impaired pulmonary surfactant production or function.
What is Ventilator-Associated Pneumonia (VAP), and how does it develop?
VAP occurs in patients who have been mechanically ventilated for more than 48 hours, often caused by microaspiration of oropharyngeal secretions and impaired mucociliary clearance.
What is the treatment for tension pneumothorax?
Tension pneumothorax is a medical emergency treated with immediate needle decompression followed by tube thoracostomy.
What are the common risk factors for pulmonary embolism (PE) in ICU patients?
Risk factors include lower limb fractures, recent hospitalization for heart failure or myocardial infarction, hip/knee replacement, major trauma, previous VTE, and immobility.
What are the main mechanisms by which atelectasis develops?
Atelectasis develops through compressive atelectasis (increased pressure on the lung), resorptive atelectasis (absorption of alveolar air distal to an obstruction), and impaired surfactant production or function.
What is the incidence of atelectasis in patients undergoing general anesthesia?
Atelectasis occurs in up to 90% of patients undergoing general anesthesia, with 15-20% of the lung at the base collapsing during anesthesia.
What are the preventative measures for atelectasis in the perioperative period?
Preventative measures include early mobilization, deep breathing exercises, incentive spirometry, continuous positive airway pressure (CPAP), low FiO2, positive end-expiratory pressure (PEEP), and lung recruitment maneuvers
What are the clinical signs of atelectasis?
Clinical signs may include decreased or absent breath sounds, crackles, cough, sputum production, dyspnea, tachypnea, and diminished chest expansion.
How is atelectasis diagnosed?
Atelectasis can be diagnosed using imaging studies such as chest X-rays, chest CT, and thoracic ultrasonography. In some cases, fiberoptic bronchoscopy is used.
What is the pathophysiology of Ventilator-Associated Pneumonia (VAP)?
VAP develops due to the presence of an endotracheal tube (ETT) or tracheostomy, which impairs secretion clearance, leading to the aspiration of contaminated oropharyngeal secretions that reach the lower airways.
What factors increase the risk of developing multidrug-resistant bacteria in VAP?
Risk factors include prolonged mechanical ventilation, previous antibiotic therapy, advanced age, chronic lung disease, aspiration, and premorbid conditions like malnutrition or renal failure.
What are the early signs of aspiration pneumonitis?
Early signs include symptoms appearing within minutes, radiographic evidence of consolidation, and pleural effusions in post-aspiration pneumonia.
What are the main causes of respiratory pump failure in Type 2 respiratory failure?
Respiratory pump failure can be caused by central nervous system depressants (e.g., alcohol, sedatives), neuromuscular diseases (e.g., ALS, Guillain-Barre syndrome), chest wall disorders (e.g., kyphoscoliosis), and diaphragmatic paralysis.
How is a pneumothorax diagnosed and treated in ICU patients?
A pneumothorax is diagnosed using imaging such as a CT scan, and treatment includes needle decompression and chest tube insertion. For persistent cases, thoracic surgery consultation may be required.
What is the significance of the Alveolar-arterial (A-a) gradient in respiratory failure?
The A-a gradient helps assess oxygenation efficiency. It is calculated as the difference between alveolar oxygen (PAO2) and arterial oxygen (PaO2). A normal or increased A-a gradient can indicate the underlying cause of hypoxemia in respiratory failure
