Final answer:
The symptom most consistent with an injury to the diaphragm is the presence of bowel sounds in the left lower chest, which indicates an abnormal displacement of abdominal contents into the thoracic cavity due to diaphragm compromise.
Step-by-step explanation:
A patient involved in a high-speed rollover complaining of increased difficulty breathing and revealing a small penetrating wound to the sixth intercostal space could be suffering from an injury to the diaphragm. Among the mentioned symptoms, the most consistent finding with a diaphragm injury would be Bowel sounds heard in the left lower chest. This is because the diaphragm separates the thoracic cavity from the abdominal cavity, and if it is compromised, abdominal contents including bowel could move into the chest cavity, causing bowel sounds to be heard in an abnormal location.
This phenomenon also explains Kehr's sign, a common clinical feature of diaphragmatic irritation which includes pain radiating to the left shoulder from the diaphragm due to referred pain pathways, particularly common in spleen injuries. The diaphragm and associated muscles, such as the intercostal muscles, play a critical role in maintaining respiratory system integrity and function. It is important that this injury is assessed promptly to prevent further complications such as respiratory distress or infection like pneumonia, which can be identified by a "shadow" on the chest radiograph due to lung infiltration. When assessing for potential diaphragmatic injuries, listen for abnormal breath sounds, assess for hypoxemia, and be aware of signs of altered intrapleural pressure or other signs of thoracic injury.