Which of the following is considered an isotonic solution?

An isotonic solution is one that has the same osmotic pressure as another solution, typically referring to the osmotic pressure of human blood plasma. In the context of intravenous solutions, this means that an isotonic solution will not cause cells to shrink or swell when introduced into the bloodstream.

0.9% Saline is classified as an isotonic solution because it has an osmolarity that is similar to that of blood, allowing for optimal fluid balance without disrupting the cellular environment. It provides necessary hydration and electrolytes and is commonly used in clinical settings for fluid resuscitation and maintenance.

Other options mentioned have different characteristics. For instance, 0.45% Sodium Chloride is hypotonic, meaning it has a lower osmolarity compared to blood plasma and can lead to cell swelling and potential lysis. Both 5% Dextrose in Water and 5% Dextrose in 0.9% Normal Saline can behave differently once metabolized – the former becomes hypotonic once the dextrose is utilized, while the latter is isotonic but the dextrose component can influence the effective osmolarity depending on the clinical context. Thus, 0.9% Saline stands out as the only straightforward isotonic