Emergency Medical Technician (EMT) Intermediate Practice Exam

What is the expected physiological result of a 34-year-old male in late shock due to blunt chest trauma with a respiratory rate of 6 breaths/min?

1. Increased oxygen levels in the blood

2. Carbon dioxide retention and acidosis

3. Improved blood circulation

4. Alkalosis due to hyperventilation

The correct answer is: Carbon dioxide retention and acidosis

In this scenario, the individual is experiencing late shock due to blunt chest trauma and has a significantly reduced respiratory rate of 6 breaths per minute. In this context, a low respiratory rate is indicative of hypoventilation, which leads to the retention of carbon dioxide (CO2) in the bloodstream. As CO2 accumulates, it reacts with water in the body to form carbonic acid, which dissociates to release hydrogen ions, thereby increasing the acidity of the blood. This process causes respiratory acidosis, as the body is unable to effectively remove CO2 due to the inadequate respiratory drive. The resulting situation is a state of hypercapnia (elevated levels of CO2) and accompanying acidosis. In conditions of shock, especially related to trauma, a patient's metabolic demands may increase while their ability to meet those demands through effective respiration and circulation decreases. As a result, this pathological state leads to significant physiological alterations, reinforcing why carbon dioxide retention and resultant acidosis is the expected outcome in this situation. The other options describe physiological responses that are not consistent with hypoventilation and shock. For instance, increased oxygen levels in the blood would typically require effective breathing and oxygen exchange, which is not being achieved here.