Pneumothorax, Week 4 Lecture

Question 1

Define pneumothorax.

Answer 1

A situation where there is positive pressure inside the thoracic cavity that is at least equal or in excess to the atmospheric pressure.

Question 2

What physical phenomenon allows for spontaneous breathing in a normal physiology?

Answer 2

Changes to the chest wall or lung volumes results in a negative pressure (in relation to atmospheric pressure) –> Allows spontaneous ventilation in humans

Question 3

What are the most common problems that lead to pneumothoraces?

Answer 3

When we violate the pleural space, we get a pneumothorax - chest wall expansion outwards and lung collapse inwards. This can be due to communication between pleural space and alveolar space, or pleural space and the external atmosphere.

Gas producing organism: infection in pleural space results in bacteria that produces gas, which generates positive pressure in the alveolar space (which removes negative pressure and causes lung to collapse)

Question 4

What can occur during inspiration in a pneumothorax?

Answer 4

Two things can happen based on location of trauma
:
1. Air will enter the chest cavity from atmosphere if there’s a hole there. Chest wall will still expand, but lung will not expand.

2. Air will be sucked out from the lung of there’s a hole there.

OR both can be occurring at the same time.

All scenarios will result in further lung collapse

Question 5

Patient is on mechanical ventilation and there’s a hole in the parenchema of the lung. What can we do to address this pneumothorax?

Answer 5

We can force air through that hole into the lung to expand it. However, for this to work, we have to have a hole in the chest wall as well, **otherwise pressure will build up in that thoracic space, causing tension pneumothorax.

Therefore, in this situation, if there isn’t a hole in the chest, we can place one there with a tube/needle to drain that pressure off.

Question 6

Describe spontaneous pneumothorax.

Answer 6

No direct injury (non-trauma pneumo) to lung or chest wall but we have a rupture of the alveoli.

-This can occur in lung diseases (e.g. emphysema = worn out alveolar sacs that become very large - lung blebs/huge alveolar balloons that can rupture)

Question 7

Difference between primary and secondary spontaneous pneumothorax.

Answer 7

Primary spontaneous pneumothorax: caused by spontaneous actions of the patient (COPD coughs)

Secondary spontaneous pneumothorax: caused under anesthetic conditions (mechanical ventilation) due to underlying disease states

Question 8

What is tension pneumothorax?

Answer 8

Air is getting into the pleural space (usually from injury to lung parenchema) and mechanical ventilation is getting more and more air into that pleural space; b/c there is no chest wall hole/exit, pressure just keeps building up in the thoracic space

Question 9

Signs and symptoms we can look for that indicate the presence of a pneumothorax.

Answer 9

• Acute onset dyspnea
• Chest pain
• Hypotension: due to increase in intrathoracic pressure which decreases amount of blood getting to the heart (pressure on venous return), which decreases ability of heart to push blood through circulation.
• Tachycardia
• Pulsus paradoxus:
• Tracheal deviation (occurs if pneumothorax is more severe on one side or unilateral and the trachea shifts away from it)

Question 10

What is pulsus paradoxus?

Answer 10

Respiratory cycle causes predictable variabilities in hemodynamics ; these hemodynamic shifts are accentuated in pulsus paradoxus (seen as noticeable up and down oscillations in BP curve)

- Inspiration = decreased BP due to chest expansion
- Expiration = increased BP due to chest squeeze

-Very profound accentuation can lead to cardiac arrest!

Question 11

Common treatment for pneumothorax

Answer 11

Evacuate pleural space (Pleur-Evac machine)

Question 12

Directions for using the Pleur-Evac.

Answer 12

• Place tube into pleural space and hook it up to a Pleur-Evac
  
  • Pleur-Evac allows us to generate and adjust negative pressure in the pleural space (commonly ~20 cm H2O)
  • Blue fluid = one way valve that does not let any air get back into pleural space
  • Air or fluid that we suck out gets collected on the right side of the device
  • Red connector is hooked up to suction on wall while corrugated tube is hooked up to patient; suction pleural space until lung re-expands.
  • Once leak in lung has healed and lung re-expanded, we can pull out the chest tube, but make sure that we seal the hole as we pull the tube out to prevent making another pneumothorax