What is the chemical cause of phlebitis?

The correct answer is based on the understanding that phlebitis is often caused by the irritation of the vascular lining due to certain solutions administered through the intravenous route. Irritating or vesicant solutions, such as certain chemotherapy agents or hypertonic solutions, can damage the endothelial cells of the blood vessels. This irritation leads to inflammation, which is the hallmark of phlebitis.

The condition occurs as a direct response to these solutions, specifically when they are either too concentrated or not compatible with the blood, leading to local swelling, redness, and discomfort at the IV site. This emphasizes the importance of knowing the properties of the solutions being infused and their potential to cause harm to the veins.

Other factors like catheter size, patient compliance, and IV site selection can contribute to phlebitis but they are not the direct chemical causes. For example, while a large catheter may cause mechanical irritation, it does not chemically irritate the vessel. Non-compliance may lead to complications but is not a chemical cause. Similarly, improper site selection may increase the risk of phlebitis but does not involve a chemical reaction. Thus, the irritative nature of certain solutions stands out as the primary chemical cause of phlebitis.