Advanced Emergency Medical Technician (AEMT) Practice Test

Lactated Ringer's and 0.9% sodium chloride solutions are classified as what type of solutions?

1. Colloid solutions

2. Crystalloid solutions

3. Hypertonic solutions

4. Hypotonic solutions

The correct answer is: Crystalloid solutions

Lactated Ringer's and 0.9% sodium chloride solutions are classified as crystalloid solutions because they contain small molecules that easily pass through semipermeable membranes, allowing them to diffuse across tissue barriers. These solutions are composed of water and electrolytes, and they are commonly used in clinical settings for fluid resuscitation and maintaining hydration. Crystalloids are characterized by their ability to increase the fluid volume in the extracellular space, which is essential in managing conditions such as dehydration or hypovolemia. Both Lactated Ringer's and 0.9% sodium chloride are isotonic solutions, meaning they have an equal concentration of solutes compared to the plasma, which helps to maintain the body's fluid balance without causing cellular swelling or shrinkage. Understanding the nature of these solutions is vital for administering appropriate fluids based on the patient's condition, such as acute injuries or surgical needs, making crystalloid solutions a key component in emergency medical practice.