**Question:** Which of the following is safe even if injected intraaerial?

**Core Concept:** Intraaerial injection refers to injecting a substance directly into the air spaces of the lungs, which can lead to severe complications due to the direct exposure of the substance to the respiratory system.

**Why the Correct Answer is Right:** The correct answer is D, "Sodium chloride (NaCl) or normal saline (NS)." NaCl is a harmless compound commonly used as a sterile isotonic solution for various medical purposes. Its injection intraaerially will not cause significant harm or toxicity due to its physiological role in maintaining osmotic balance and fluid homeostasis within the body, particularly in the respiratory tract.

**Why Each Wrong Option is Incorrect:**
A. **Albumin:** Intraaerial injection of albumin can lead to severe pulmonary edema and respiratory distress due to excessive fluid accumulation in the lungs.
B. **Calcium chloride (CaCl2):** Calcium chloride is a highly toxic substance that can cause severe pulmonary toxicity, cardiac arrhythmias, and systemic toxicity upon intraaerial injection.
C. **Glucose:** Intraaerial injection of glucose can lead to severe hyperosmolarity and pulmonary edema, resulting in respiratory distress and failure.

**Clinical Pearl:** Intraaerial injection of substances should be avoided due to the potential for severe complications. However, certain physiological substances like NaCl or NS can be safely used for specific purposes (e.g., flushing bronchoscopes), while others like albumin, CaCl2, and glucose should be strictly avoided due to their potential for causing severe pulmonary and systemic toxicity.