Which statement about isotonic fluids in resuscitation is true?

Which statement about isotonic fluids in resuscitation is true?

• A. Isotonic fluids are used to restore circulating volume in hypovolemic shock
• B. Hypertonic solutions are preferred in most shock cases
• C. Dextrose solutions are the first choice for volume expansion
• D. Hypotonic fluids are most effective for resuscitation

Answer: (A)

The key idea is that resuscitation aims to rapidly restore intravascular volume to improve preload and perfusion. Isotonic fluids have osmolality similar to plasma, so they stay mostly in the intravascular space and expand circulating volume without pulling water into or out of cells. This makes them the most effective and appropriate choice for treating hypovolemic shock in many cases. Normal saline and lactated Ringer’s are common examples used for this purpose. Hypertonic solutions can draw water out of cells into the bloodstream but are used selectively and carry risks with rapid shifts in fluid balance, so they aren’t the default for most shock cases. Dextrose-containing solutions like D5W start isotonic but, after glucose is metabolized, become hypotonic and can lead to fluid movement out of the vasculature, not ideal for volume expansion. Hypotonic fluids pull fluid into cells, reducing intravascular volume and potentially worsening hypotension.

The key idea is that resuscitation aims to rapidly restore intravascular volume to improve preload and perfusion. Isotonic fluids have osmolality similar to plasma, so they stay mostly in the intravascular space and expand circulating volume without pulling water into or out of cells. This makes them the most effective and appropriate choice for treating hypovolemic shock in many cases. Normal saline and lactated Ringer’s are common examples used for this purpose.

Hypertonic solutions can draw water out of cells into the bloodstream but are used selectively and carry risks with rapid shifts in fluid balance, so they aren’t the default for most shock cases. Dextrose-containing solutions like D5W start isotonic but, after glucose is metabolized, become hypotonic and can lead to fluid movement out of the vasculature, not ideal for volume expansion. Hypotonic fluids pull fluid into cells, reducing intravascular volume and potentially worsening hypotension.