Lung Pathology in ICU

Question 1

What are the two types of respiratory failure?

Answer 1

Type 1 and 2

Question 2

What is type 1 Respiratory failure?

Answer 2

Respiratory system cannot adequately provide oxygen to the body leading hypoxemia

Question 3

What are the causes of Type 1 respiratory failure?(5)

Answer 3

Caused by alveolar hypoventilation
Low atmospheric pressure/fraction of inspired oxygen
Diffusion defect
Ventilation/perfusion mismatch
Right-to-left shunt

Question 4

How is the partial pressure of O2 and CO2 affected in Type 1 Respiratory Failure?

Answer 4

Partial pressure of oxygen (PaO2) < 60 mmHg
Normal or decreased partial pressure of carbon dioxide (PaCO2)

Question 5

What is Alveolar-arterial gradient? And how is it affected in type 1 respiratory failure?

Answer 5

A-a gradient = PAO2 - PaO2
PAO2= Alveolar partial pressure of oxygen
PaO2 = Arterial partial pressure of oxygen

It may be normal or increased.

Question 6

What is Type 2 respiratory Failure?

Answer 6

Occurs when the respiratory system cannot adequately remove carbon dioxide from the body leading to hypercapnia

Question 7

What is the MOA of type 2 respiratory failure?

Answer 7

1.Respiratory pump failure
2.Increased carbon dioxide production

Question 8

How is the partial pressure of co2 affected and the pH in type 2 respiratory failure.

Answer 8

Arterial carbon dioxide (CO2) (PaCO)> 45 mmHg
pH < 7.35

Question 9

What makes up the respiratory pump(4)

Answer 9

It is comprised of the
-chest wall
-the pulmonary parenchyma
-the muscles of respiration
-as well as the central &peripheral nervous systems.

Question 10

What are the causes of respiratory pump failure?

Answer 10

1. 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

Question 11

What are the causes of Increased CO2 production? And when does high CO 2 production become pathologic?

Answer 11

1.fever
2. exercise
3.hyperalimentation
4.sepsis
5.Thyrotoxicosis.

High CO2 production becomes pathologicif the compensatory increase in minute ventilation mechanism fails.[16]

Question 12

What is Aspiration Pneumonitis? What is the other name for it?

Answer 12

Toxic fluid aspiration of gastric fluid with a pH of < 2.5 (Mendelsohn’s syndrome)

Question 13

What is the consequence of aspirating neutral pH gastric contents?

Answer 13

Tracheobronchial irritation

NB: not chemical irritation

Question 14

What is seen on an x-ray in aspiration pneumonitis?

Answer 14

Consolidation

Question 15

How long does Aspiration pneumonia take to show symptoms?

Answer 15

Minutes

Question 16

What are the consequences of a massive aspiration pneumonitis?

Answer 16

It can progress to a full blown ARDS

Question 17

What is done next if the infection(Aspiration Pnuemonitis)does not show evidence of clearing within a few days of antibiotic adminstration?

Answer 17

A CT scan

Question 18

What are the most common types of Atelectasis?

Question 19

How does Atelectasis improve?

Answer 19

Via physical therapy

Question 20

What is the number one risk factor to VAP?

Answer 20

A cuffed ETT or Tracheostomy

Question 21

In what kind of patients does VAP occur in?

Answer 21

People who have undergone mechanical ventilation for at least 48hrs

Question 22

What are the 2 types of VAPs? and what are their causes?

Answer 22

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

Question 23

What are the risk factors for VAP?(6)

Answer 23

-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

Question 24

What are the risk factors for developing Late onset VAP?(5)

Answer 24

Acute respiratory distress syndrome
Frequent ventilator circuit changes
Polytrauma patient
Prolonged paralysis
Premorbid conditions such as malnutrition, renal failure, and anaemia

Question 25

Describe the pathophysiology of VAP?

Answer 25

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.

Question 26

How is VAP treated?

Answer 26

early diagnosis, and initiation of antibiotics tailored to the results of microbiological specimens

Question 27

What are the MOA of a pneumothorax?

Answer 27

1.Barotrauma 2.Iatrogenesis

Question 28

What kind of patients are at a high risk of developing a pneumothorax?

Answer 28

Patients with an underlying lung disease

Question 29

What type of pnuemothorax is a medical emergency and how is it resolved?

Answer 29

Tension pneumothorax is a medical emergency, and managed with immediate needle decompression followed by tube thoracostomy

Question 30

What is the gold standard for a pneumothorax?

Answer 30

CT

Question 31

What happens if there is a persistent air leak?

Answer 31

Consult the surgeons

Question 32

In non surgical candidates of a pneumothorax what is done?

Answer 32

REFER TO HANDOUT

Question 33

What are the risk factors for a P.E?(6)

Answer 33

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

Question 34

What are the symptoms of somone with a P.E?

Answer 34

Dyspnea Chest Pain Syncope/pre-syncope Hemoptysis

Question 35

How do you treat a P.E?

Answer 35

1.Low molecular weight heparin (LMWH) and unfractionated heparin (UFH). 2.Mechanical thromboprophylaxis with intermittent pneumatic compression (IPC) With Critical care ultrasonography (CCUS) .