Pneumothorax

Question 1

When does pneumothorax happen?

Answer 1

When there is the presence of air within the pleural space, the potential space between the parietal and visceral pleura

Question 2

What is a pnemothorax?

Answer 2

A collection of air outside the lung but within the pleural cavity

Question 3

What can the accumulated air between the parietal and visceral pleurae inside the chest do?

Answer 3

It can apply pressure onto the lung and make it collapse
The degree of collapse determine the clinical presentation

Question 4

Through which mechanisms can air enter the pleural space?

Answer 4

Trauma causing communication through the chest wall
Rupture of the visceral pleura

Question 5

What are the two types of pneumothorax?

Answer 5

Traumatic
Atraumatic

Question 6

What are the subtypes of atraumatic pneumothorax?

Answer 6

Primary
Secondary

Question 7

How is pleural pressure maintained under normal physiological conditions?

Answer 7

Balance between two opposing forces that generate a negative pressure of approximately -5cmH₂O (cm of water) within the pleural space.
Ensures the lungs stay expanded against the chest wall
Presence of pulmonary surfactants

Question 8

What are the opposing forces that balance to maintain pleural pressure?

Answer 8

Hydrostatic pressure
Oncotic pressure

Question 9

What is hydrostatic pressure?

Answer 9

The force of fluid pushing against the walls of the pulmonary capillaries
Normally around 8-10mmHg

Question 10

What is oncotic pressure?

Answer 10

The osmotic pressure exerted by proteins in the plasma that are too large to pass through the pulmonary capillaries

Question 11

What is the hydrostatic pressure from the parietal space going into the pleural space?

Answer 11

+30cm of water

Question 12

What is the hydrostatic pressure from the visceral space going into the pleural space?

Answer 12

+24cm of water

Question 13

What is the oncotic pressure going out from the pleural space into the patrietal and visceral space?

Answer 13

+34cm of water

Question 14

What is the hydrostatic pressure in the pleural space?

Answer 14

-5cm of water

Question 15

What is the oncotic pressure in the pleural space?

Answer 15

+5cm of water

Question 16

What does the presence of pulmonary surfactants allow for?

Answer 16

The smooth movement of the lungs during respiration while maintaining a negative pressure relative to the astmosphere

Question 17

What is the result of having a pneumothorax?

Answer 17

A change in the pressure gradient inside the thorax

Question 17

What happens to lung mechanics in a pneumothorax?

Answer 17

Normally, the pleural space has negative pressure (vs atmospheric), keeping lungs expanded
Elastic recoil would make the lungs collapse without the negative pressure
In pneumothorax, air enters pleural space from alveoli
This eliminates the pressure gradient
Lung collapses until pressure equilibrium is reached
Results in reduced lung size, reduced vital capacity, reduced oxygen partial pressure (PaO2)

Question 18

Clinical presentation can range from what?

Answer 18

Asymptomatic to chest pain and shortness of breath

Question 19

What is a tension pneumothorax?

Answer 19

A life-threatening emergency
Large air collection in the pleural space compromises respiration and cardiac function

Question 20

When might tension pneumothorax occur?

Answer 20

Trauma
Aggressive mechanical ventilation
Resuscitation

Question 21

What can tension pneumothorax cause?

Answer 21

Severe hypotension (obstructive shock)
Death

Question 22

What can increased central venous pressure result in?

Answer 22

Distended neck veins
Hypotension

Question 23

Patients may present with what?

Answer 23

Tachypnoea - rapid breathing
Dyspnoea - shortness of breath
Tachycardia - rapid heart rate
Hypoxia

Question 24

What are the three classifications of pneumothorax?

Answer 24

Spontaneous Traumatic Tension

Question 25

When does a spontaneous pneumothorax happen?

Answer 25

Without an external traumatic event Caused by the rupture of bullae

Question 26

What is bullae?

Answer 26

Air-filled sacs that develop on the surface of the lung

Question 27

When do bullae form?

Answer 27

When alveoli develop microscopic leaks Air seeps into the surrounding lung tissue

Question 27

What happens if the bullae rupture?

Answer 27

A direct communication between the lung's airways and the pleural space will occur Allows air to escape into the pleural cavity

Question 28

Describe a primary spontaneous pneumothorax (PSP)

Answer 28

Occurs in those without underlying lung disease Mainly occurs in tall and thin young people due to increased shear forces or more negative pressure at the apex of the lung

Question 29

What is essential to the pathogenesis of PSP?

Answer 29

Lung inflammation Oxidative stress

Question 30

What is oxidative stress?

Answer 30

An imbalance of free radicals and antioxidants in the body that leads to cell damage/death

Question 31

Why do smokers/vapers have an increased risk of pneumothorax?

Answer 31

Increased inflammatory cells in the small airways Airway damage and weakening

Question 32

When does secondary spontaneous pneumothorax (SSP) happen?

Answer 32

Occurs in the presence of underlying lung disease

Question 33

Which underlying lung diseases are the primary cause of SSP?

Answer 33

COPD TB Sarcoidosis CF Malignancy Idiopathic pulmonary fibrosis Pneumonia caused by pneumocystis jiroveci

Question 34

What is pneumocystis jiroveci?

Answer 34

A yeast-like fungus of the genus pneumocystis

Question 35

When can a traumatic pneumothorax happen?

Answer 35

Blunt or penetrating trauma Normally creates a one-way valve in the pleural space - air flow in but not out Resulting in a hemodynamic compromise

Question 36

Where is tension pneumothorax most common?

Answer 36

ICU settings in positive-pressure ventilated patients

Question 37

What is iatrogenic pneumothorax?

Answer 37

Included under traumatic pneumothorax Complication of mechanical ventilation, lung biopsies, thoracentesis

Question 38

What is thoracentesis?

Answer 38

Procedure to remove fluid or air from the pleural space