Lung Pathology in ICU Flashcards
What are the two types of respiratory failure?
Type 1 and 2
What is type 1 Respiratory failure?
Respiratory system cannot adequately provide oxygen to the body leading hypoxemia
What are the causes of Type 1 respiratory failure?(5)
Caused by alveolar hypoventilation
Low atmospheric pressure/fraction of inspired oxygen
Diffusion defect
Ventilation/perfusion mismatch
Right-to-left shunt
How is the partial pressure of O2 and CO2 affected in Type 1 Respiratory Failure?
Partial pressure of oxygen (PaO2) < 60 mmHg
Normal or decreased partial pressure of carbon dioxide (PaCO2)
What is Alveolar-arterial gradient? And how is it affected in type 1 respiratory failure?
A-a gradient = PAO2 - PaO2
PAO2= Alveolar partial pressure of oxygen
PaO2 = Arterial partial pressure of oxygen
It may be normal or increased.
What is Type 2 respiratory Failure?
Occurs when the respiratory system cannot adequately remove carbon dioxide from the body leading to hypercapnia
What is the MOA of type 2 respiratory failure?
1.Respiratory pump failure
2.Increased carbon dioxide production
How is the partial pressure of co2 affected and the pH in type 2 respiratory failure.
Arterial carbon dioxide (CO2) (PaCO)> 45 mmHg
pH < 7.35
What makes up the respiratory pump(4)
It is comprised of the
-chest wall
-the pulmonary parenchyma
-the muscles of respiration
-as well as the central &peripheral nervous systems.
What are the causes of respiratory pump failure?
- Decrease central respiratory drive due to: Sedatives (i.e., alcohol, benzodiazepines, and opiates) and diseases of the central nervous system (i.e., encephalitis, stroke, tumor, and SCI)
2.Altered neural and neuromuscular transmission: Amyotrophic lateral sclerosis, botulism, Guillain-Barre syndrome, myasthenia graves, organophosphate poisoning, poliomyelitis, spinal cord injury (SCI),tetanus, and transverse myelitis
3.Chest wall and pleural disorders: Flail chest, kyphoscoliosis, hyperinflation, large pleural effusions, obesity, and thoracoplasty
4.Dead space Ventilation: Conditions that increase the V/Q ratio, such as acute respiratory distress syndrome, bronchitis, bronchiectasis, emphysema, and pulmonary embolism
5.Muscle abnormalities: Diaphragmatic paralysis, diffuse atrophy, muscular dystrophy, and ruptured diaphragm
What are the causes of Increased CO2 production? And when does high CO 2 production become pathologic?
1.fever
2. exercise
3.hyperalimentation
4.sepsis
5.Thyrotoxicosis.
High CO2 production becomes pathologicif the compensatory increase in minute ventilation mechanism fails.[16]
What is Aspiration Pneumonitis? What is the other name for it?
Toxic fluid aspiration of gastric fluid with a pH of < 2.5 (Mendelsohn’s syndrome)
What is the consequence of aspirating neutral pH gastric contents?
Tracheobronchial irritation
NB: not chemical irritation
What is seen on an x-ray in aspiration pneumonitis?
Consolidation
How long does Aspiration pneumonia take to show symptoms?
Minutes
What are the consequences of a massive aspiration pneumonitis?
It can progress to a full blown ARDS
What is done next if the infection(Aspiration Pnuemonitis)does not show evidence of clearing within a few days of antibiotic adminstration?
A CT scan
What are the most common types of Atelectasis?
How does Atelectasis improve?
Via physical therapy
What is the number one risk factor to VAP?
A cuffed ETT or Tracheostomy
In what kind of patients does VAP occur in?
People who have undergone mechanical ventilation for at least 48hrs
What are the 2 types of VAPs? and what are their causes?
Early onset VAP -occurs within the first 4 days of MV and is caused by Antibiotic sensitive community acquired bacteria e.g Hemophilus and Streptococcus
Late Onset VAP - Develops more than 5 days after initiation of MV is usually caused by
multidrug–resistant bacteria such as Pseudomonas aeruginosa
What are the risk factors for VAP?(6)
-increasing age (.55 years)
-Chronic lung disease
-Aspiration/ microaspiration from being nursed in a supine position
-Chest or upper abdominal surgery
-Previous antibiotic therapy, especially broad-spectrum antibiotics
-Reintubation after unsuccessful extubation, or prolonged intubation
What are the risk factors for developing Late onset VAP?(5)
Acute respiratory distress syndrome
Frequent ventilator circuit changes
Polytrauma patient
Prolonged paralysis
Premorbid conditions such as malnutrition, renal failure, and anaemia
Describe the pathophysiology of VAP?
The key to the development of VAP is the presence of an ETT or tracheostomy, both of which interfere with the normal anatomy
and physiology of the respiratory tract, specifically the functional mechanisms involved in clearing secretions (cough and
mucociliary action). Intubated patients have a reduced level of consciousness that impairs voluntary clearance of secretions,
which may then pool in the oropharynx.4 This leads to the macroaspiration and microaspiration of contaminated oropharyngeal
secretions that are rich in harmful pathogens.
In addition normal oral flora start to proliferate and are able to pass along the tracheal tube, forming an antibiotic-resistant biofilm which
eventually reaches the lower airways.
Critically unwell patients exhibit an impaired ability to mount an immune response to
these pathogens, leading to the development of a pneumonia.
How is VAP treated?
early diagnosis, and initiation of antibiotics tailored to the results of microbiological specimens
What are the MOA of a pneumothorax?
1.Barotrauma
2.Iatrogenesis
What kind of patients are at a high risk of developing a pneumothorax?
Patients with an underlying lung disease
What type of pnuemothorax is a medical emergency and how is it resolved?
Tension pneumothorax is a medical emergency, and managed with immediate needle decompression followed by tube thoracostomy
What is the gold standard for a pneumothorax?
CT
What happens if there is a persistent air leak?
Consult the surgeons
In non surgical candidates of a pneumothorax what is done?
REFER TO HANDOUT
What are the risk factors for a P.E?(6)
lower limb fracture
hospitalization for heart failure or myocardial infarction within the past 3 months
hip or knee replacement
major trauma or spinal cord injury
previous VTE
What are the symptoms of somone with a P.E?
Dyspnea
Chest Pain
Syncope/pre-syncope
Hemoptysis
How do you treat a P.E?
1.Low molecular weight heparin (LMWH) and unfractionated heparin (UFH).
2.Mechanical thromboprophylaxis with intermittent pneumatic compression (IPC)
With Critical care ultrasonography (CCUS) .
