Pressor response to 30-s breathhold: a predictor of masked hypertension.

One in six adults has normal arterial blood pressure (BP) during a routine examination, but is hypertensive in other environments. This masked hypertension (MHT) may delay treatment until target organ damage has occurred. A sensitive, specific and economical test is needed to detect or exclude MHT in apparently normal subjects. The BP response to a 30-s breathhold (BH test) was observed in 269 young subjects with no evidence of cardiovascular disease. Of 226 normotensives (office BP ≤ 120/80), 25 (11%) had a positive BH test (test BP > 140/90 mmHg), and 12 (44%) of these subjects had MHT (positive 24-h ambulatory BP monitoring (BPM)). Of 201 subjects with negative BH test, none had MHT (negative BPM). Of 43 subjects with high normal BP (office BP > 120/80 < 140/90), 28 (65%) had a positive BH test and 22 of these subjects had MHT (positive BPM). Of the 15 subjects with high normal BP and with a negative BH test, none had MHT (negative BPM). Overall, the BH pressor test and BPM agreed in 93% of cases, and the BH test produced no false negative findings. The BH pressor test effectively ruled out MHT in normal subjects and accurately identified a population that should be further evaluated for MHT.