Within respiratory anatomy and function is the Pleura and Pleural Cavity. The Pleura consists of a closed sac of serous membrane which surrounds each lung. The Pleura lines the outer walls of the lungs (Visceral Pleura) and the inner surface of the chest wall (Parietal Pleura), with a small amount of Serous fluid in the Pleural Cavity in between. The small amount of Serous fluid in the cavity, around 7-10 ml, allows for the friction free movement of the lungs against the chest wall during inspiration and expiration. The surface tension created between the two sides and Serous fluid also means that it is very difficult for the lung to come away from the inner chest wall. There is no air within the Pleural Cavity, only fluid, and this creates a negative pressure within relative to atmospheric pressure.
A pneumothorax/haemothorax occurs when air or fluid enters the pleural cavity, turning the negative pressure to positive. This positive pressure prevents lung expansion and effects the respiration actions of the patient. Air will usually collect towards the top of the lungs, the apex, whereas fluid typically collects at the bases of the lungs.
In a simple pneumothorax, air will collect within the pleural cavity and affect the respiration effectiveness of the injured section. The patient may have difficulty in breathing, pain, reduced air entry, and hyper-resonance on the affected site. A simple pneumothorax doesn’t require needle thoracocentesis intervention within the pre-hospital context.
In a tension pneumothorax, the complication arises when a flap or one-way valve manages to develop between the lungs and the pleural cavity. Air enters the space during inspiration but cannot escape on expiration. The air in the cavity increases and this expansion pushes against the affected lung and mediastinum (central thoracic organs). As pressure continues to build, the mediastinum is pushed and compressed against the unaffected side of the thorax. All of this causes significant compression on the affected lung, the heart and great vessels in the central thorax, and the unaffected lung. This creates great respiratory and cardiovascular compromise and if not rectified quickly will result in death. Signs and symptoms can include significant difficulty in breathing and reduced air entry, tachypnoea or bradypnoea, chest pain, vital sign compromise, tracheal deviation, surgical emphysema, jugular vein distention, and hyper-resonance.
Haemothorax is where blood collects within the pleural cavity causing pressure on the lung and mediastinum. Often caused through trauma, a large amount of blood can collect within the pleural cavity. Signs and symptoms can include difficulty in breathing and reduced air entry, pain, and hypo-resonance on the affected side.
Open pneumothorax, or a sucking chest wound occurs where a penetrating injury to the chest causes an opening, allowing air to enter the pleural cavity. Signs and symptoms can include difficulty in breathing and reduced air entry, pain, a sucking sound at the wound, and hyper-resonance at the affected site.
A trauma patient suffering from tension pneumothorax/significant haemothorax can deteriorate very quickly, and quick assessment, identification, and management will be required to try to stabilise them.
The FLAPS TWELVE mnemonic can be used to quickly and strategically identify if there are any deficits of pneumo/haemothorax concern:
Feel – Assess the rise and fall of the chest. If it is not equal, there may be a pneumothorax or developing tension pneumothorax occurring. Through palpation you may also feel any abnormal landmarks, such as potential rib deformities/fractures, surgical emphysema, pain/tenderness.
Look – Following the same principles as feel, look for equal rise and fall of the chest and any structural abnormalities/injury.
Auscultate – Auscultate all lobes of the lungs to listen for any abnormalities. If there is reduced or no air entry, this may indicate a pneumothorax.
Percuss – Percussion of the thorax can help identify any hyper/hypo-resonance. A build up of air in the cavity would give a hyper-resonance indicating a pneumothorax/tension pneumothorax, whereas a build up of fluid/blood would give a hypo-resonance.
Search – Search the back and sides for any hidden injuries that could be missed. A sucking chest wound could develop a tension pneumothorax if not identified.
Trachea – Review the trachea to identify any obvious injury or deviation. Deviation of the trachea is often a late sign in a tension pneumothorax.
Wounds – Search the neck for any wounds that may affect the patients’ respiratory capability.
Emphysema (Surgical) – Surgical emphysema is where air has escaped into the subcutaneous tissues (the layer under the skin). This can be a late sign in a tension pneumothorax.
Larynx – Review the larynx for any injury or deformity that may indicated potential respiratory compromise.
Veins (distended) – As pressure build within the pleural space, the lungs and mediastinum begin to compress. Compression on the heart and great vessels reduces the flow of blood, this can be seen in a back up of blood in the veins. If the patient has distended jugular veins, this may be a late indication of a tension pneumothorax.
Evaluate – After the detailed respiratory review, evaluate what treatment your patient needs.