How do elevated body temperature or cold environment affect BP readings?

• A. Temperature has no effect on BP
• B. Cold lowers BP
• C. Hot increases BP
• D. Cold can raise BP; heat or warm environment may reduce readings; acclimate to room temperature before measurement

Answer: (D)

Temperature affects blood pressure readings because it changes vascular tone and even circulating volume. In a cold environment, the body activates sympathetic responses that constrict peripheral blood vessels, increasing systemic vascular resistance. This tends to raise both systolic and diastolic blood pressure, so readings can appear higher than the true resting value. In a warm or hot environment, blood vessels dilate to dissipate heat, reducing peripheral resistance and often lowering the measured blood pressure. Because these temperature-related shifts can skew the result, it’s best to measure BP after the patient has acclimated to room temperature and is at rest, with the arm supported at heart level. This helps ensure a more accurate, reproducible reading.