Are hypotonic crystalloids commonly used? Why or why not?

• A. Yes - they reduce edema
• B. Yes - they improve hydration
• C. No - cellular lysis
• D. No - they are too expensive

Answer: (C)

The main concept is tonicity and how intravenous fluids move water across cell membranes. Hypotonic crystalloids have lower osmolality than body fluids, so when they’re given, water shifts from the bloodstream into cells to equalize osmolality. This causes cells to swell, and in red blood cells that can lead to hemolysis (cellular lysis). Because of this risk, these fluids aren’t used routinely for resuscitation or hydration; isotonic crystalloids are preferred for expanding extracellular fluid without causing dangerous cellular swelling, and hypertonic solutions are used only in specific, tightly monitored situations. Therefore, the correct reasoning is that they’re not commonly used due to the potential for cellular swelling and lysis. The other options misstate the effect or relevance (they don’t reliably reduce edema, aren’t chosen primarily for hydration benefits in this context, and cost isn’t the driving factor).