Which signs suggest dehydration in an emergency patient exposed to hot conditions?

• A. Tachycardia, hypotension on exertion, dry mucous membranes, skin turgor changes, oliguria
• B. Bradycardia, moist mucous membranes, clear lungs
• C. Hypertension, sweating, flushed skin
• D. Confusion only after prolonged exposure to heat

Answer: (A)

Dehydration from heat exposure causes a loss of circulating fluid (hypovolemia), and the body responds with signs that reflect this fluid deficit. The heart speeds up to maintain blood flow, which shows up as tachycardia, and activity or exertion can reveal low blood pressure due to reduced preload. Classic physical signs of dehydration include dry mucous membranes and skin that tents or loses elasticity (skin turgor changes), along with reduced urine production (oliguria) as the kidneys conserve water. Together, these findings—rapid pulse, low pressure with exertion, dry mucous membranes, skin tenting, and little urine—best indicate dehydration in someone who has been in hot conditions.

The other options don’t fit as well because they either show signs that aren’t typical of dehydration (such as bradycardia and moist membranes) or mix in heat-related signs (like hypertension or sweating) without dehydration-specific markers. Confusion can occur with heat illness, but it isn’t a dehydration sign by itself and doesn’t point to the fluid-deficit pattern described above.