Wilderness and Rescue Medicine 8th Edition

39

Section II: Critical Body Systems

inspiration, the chest wall collapses. Hemothorax and pneumothorax are terms used to describe the presence of blood and/or air in the chest cavity in the pleural space between the lungs and the chest wall preventing full expansion of the lungs. A tension pneumothorax develops when air accumulates in the pleural space under pressure, shifting the heart and airways out of position and putting pressure on the great vessels of the circula- tory system. It should be suspected with increas- ing respiratory distress, asymmetrical chest wall expansion, and deteriorating vital signs. In the rare case of an open pneumothorax, sometimes called a sucking chest wound, air may enter the chest cavity through a hole in the chest wall. The usual cause is a knife or gunshot wound. The generic treatment for respiratory distress, like the field treatment for volume shock, is lim- ited and only temporary. The patient with chest injury significant enough to cause respiratory distress needs a surgeon and a hospital. Assist the patient into whatever position allows for the best respiration and the least pain. Call for early advanced life support with pain medication, air- way management and, in the case of suspected pneumothorax, emergency chest decompression.

Nervous System Drive The usual problem with nervous system drive is increased respiratory drive. Hyperventilation occurs with altitude, exercise, injury, and ill- ness and is a normal response to physiological demands that require more oxygen and produce more carbon dioxide. Increased respiration also occurs with acute stress reaction (ASR), but not in response to an increased need. Fortunately, the condition is self-limiting. The result of hyperventilation in ASR can be an abnormal decrease in the carbon dioxide concen- tration in the blood with the associated abnormal increase in pH. This out-of-balance blood chem- istry can produce a variety of nervous system symptoms that are referred to as hyperventila- tion syndrome . The mechanism can be dramatic and emotional, or quite subtle. A slight increase in respiratory depth and rate over enough time will cause it. Typically, the patient will complain of tingling of the hands and feet and numbness around the mouth. The patient may feel paralyzed, but their ability to move is not actually impaired. Vision may be affected with the patient seeing spots or experiencing a narrowed visual field. The symp- toms may fuel further ASR and exacerbate the hyperventilation. The patient may ultimately faint, which will cure the problem. It can be difficult to distinguish between hyper- ventilation syndrome and serious critical sys- tem problems, especially if there is a significant mechanism of injury. As with other components of acute stress reaction, however, it gets better with time, reassurance, and pain control. Telling the patient that hyperventilation is the cause of their symptoms almost always cures it.

Chest Wall Trauma

General Principles

12

closed pneumothorax

open hemo- pneumothorax

open pneumothorax

flail chest

“Pain is the most common cause of respiratory distress in chest wall trauma. Treating the pain can improve respiration, even in the presence of significant injury.”

© 2018 WMA

Open chest wounds with air bubbling in and out of the defect should be covered with an airtight seal, like a piece of plastic bag or duct tape. You do not need to make a one-way valve or coordinate the patch placement with inspiration. Just put it on. If applying a patch improves the situation, leave it in place. If symptoms become worse dur- ing evacuation, remove it.