Pneumothorax

what is a pneumothorax

a condition where gas enters the pleural space, separating the visceral and parietal pleura, and causing an increase in intrapleural pressure

how is the etiology of a pneumothorax determined

by identifying how gas has entered the pleural space

what are the three main ways gas can enter the pleural space

a perforation in the visceral pleura, the atmosphere through a perforation in the chest wall and parietal pleura, an empyema that contains gas forming microorganisms 

what is an open pneumothorax

when the pleural space is in contact with atmospheric air

what is a closed pneumothorax

when the pleural space is not in contact with atmospheric air

what are the three etiologic forms of pneumothorax

traumatic, spontaneous, and iatrogenic pneumothorax

what causes a traumatic pneumothorax

physical injury to the chest, such as penetrating wounds, piercing injuries, or crushing chest trauma

what is an open pneumothorax in trauma

caused by a penetrating wound creating an opening from the chest wall into the pleural space

what is a piercing chest wound pneumothorax

acts like a closed pneumothorax; air enters during inspiration but cannot escape during exhalation (one-way valve)

what happens in a crushing chest injury pneumothorax

the visceral pleura can be torn by a fractured rib, causing a closed pneumothorax

what is a spontaneous pneumothorax

a closed pneumothorax that occurs suddenly without an apparent cause, often secondary to lung diseases like TB, COPD, or pneumonia

what is an iatrogenic pneumothorax

a pneumothorax caused by a medical procedure or diagnostic test

what medical procedures can lead to an iatrogenic pneumothorax

mechanical ventilation, tracheostomy, or pleural biopsy

what happens to intrapleural pressure in a pneumothorax

it increases as gas accumulates in the pleural space

how does increased intrapleural pressure affect the alveoli

it compresses the underlying alveoli, increasing elastic recoil

when does atelectasis occur in pneumothorax

when intrapleural pressure exceeds intra-alveolar pressure

how does pneumothorax affect the chest wall

high intrapleural pressure pushes the chest wall outward, causing expansion

what major structures can shift or be compressed due to pneumothorax

the mediastinum, inferior vena cava, superior vena cava, and the heart

what type of pneumothorax can develop into a tension pneumothorax

a closed pneumothorax

what happens as intrapleural pressure continues to rise in a tension pneumothorax

elastic recoil increases and alveoli collapse (atelectasis)

what causes atelectasis in a tension pneumothorax

intrapleural pressure becomes greater than intra-alveolar pressure

what major shift occurs during a tension pneumothorax

complete mediastinal shift away from the affected lung

which structures are compressed due to the mediastinal shift

the interior vena cava, superior vena cava, and heart

what are the cardiovascular effects of this compression

decreased venous return leading to decreased cardiac output and blood pressure

how does direct compression of the heart affect cardiac output

it reduces cardiac output, leading to low blood pressure

what type of shunts can result from a pneumothorax

relative and absolute shunts

what cardiovascular effect can occur due to a pneumothorax

hypotension

why is there a risk of alveolar hypoventilation in pneumothorax

because increased elastic recoil opposes lung inflation, increasing the work of breathing

what can increased work of breathing lead to

risk of hypercapnia and respiratory failure

is hypoventilation common in pneumothorax

no

what is Pendelluft

the movement of air back and forth between the affected and unaffected lung in a pendulum like fashion

with which type of pneumothorax can Pendelluft occur

only with an open pneumothorax

why does Pendelluft occur in an open pneumothorax

because pressure changes between the lungs and the atmosphere allow air to shift during the breathing cycle

what happens to the mediastinum during inspiration in Pendelluft

it shifts toward the unaffected lung due to negative intrapleural pressure on that side

what happens during exhalation in Pendelluft

the mediastinum moves back toward the affected side, pushing some exhaled air from the good lung into the affected lung

how does Pendelluft contribute to impaired gas exchange

it causes paradoxical gas movement, contributing to a shunt

what are the typical signs of a small pneumothorax

mild tachycardia, mild hypoxemia with increased RR, and mild BP increase due to anxiety.

what are the typical signs of a large pneumothorax

increased RR, signs of respiratory distress, increased HR, and decreased BP if venous return is affected

what chest assessment findings suggest a pneumothorax

diminished breath sounds, hyperresonant percussion, tracheal shift, displaced heart sounds, and increased chest size (if large)

what PFT changes are seen with pneumothorax

loss of lung volumes

what ABG results are common in pneumothorax

acute respiratory alkalosis; respiratory acidosis is rare

how does a pneumothorax appear on a chest xray

increased translucency on the affected side, mediastinal shift, depressed diaphragm, and possible atelectasis (appears as opacity)

what happens during a tension pneumothorax

a large, closed pneumothorax causes complete lung collapse, mediastinal shift, and compression of the heart and the opposite lung

what side effects can a tension pneumothorax cause

decreased venous return, reduced cardiac output, and severe respiratory distress

how is management of pneumothorax determined

by the degree of lung collapse

how is a small pneumothorax (15–20% collapse) managed

bed rest or limited activity, air is usually reabsorbed within 30 days

how is a large pneumothorax (>20% collapse) treated

the air should be evacuated from the pleural space using needle decompression or chest tube placement

what is simple aspiration used for

small spontaneous pneumothoraxes when the air leak has healed and re-expansion can occur

what are the two main drainage options for treating a pneumothorax

pig tail catheter (small bore chest tube) and large bore chest tube

what are the types of chest drainage systems

wet or dry drainage systems

what are additional treatments for pneumothorax

oxygen therapy, hyperinflation techniques, and pleurodesis

what is pleurodesis used for

to treat recurrent pneumothoraxes

how does pleurodesis work

a substance is injected into the pleural space, causing inflammation that makes the lung adhere to the chest wall and seals the tear

do most pneumothorax patients require mechanical ventilation

no

what should be done before chest tube placement in a ventilated patient

minimize or remove PEEP to prevent worsening the pneumothorax

what occurs during positive pressure ventilation with a chest tube in place

bubbling in the water seal chamber during inspiration

what can continuous bubbling during PEEP indicate

the PEEP is too high, or an air leak is present