LOAD limits for ambulatory pulse pressure and double product in normotensive and hypertensive subjects

The aim of this study was to to determine possible daytime (awake hours) and nighttime (sleeping hours) LOAD limits for ambulatory pulse pressure (PP) and double product (DP) in hypertensive (HT) subjects and secondly to assess whether there were significant differences in the LOAD values between hypertensive (HT) and normotensive (NT) subjects.

Seventy-eight untreated essential HT (46 female, 32 male; mean age 51.9+/-1.4 years) and 115 NT (89 female, 26 male; mean age 40.8+/-1.1 years) subjects participated in this study. Ambulatory blood pressure monitoring (ABPM) devices were applied to these subjects for 48 hours. Different possible ambulatory PP LOAD limits between 40 and 55 mmHg with 5 mmHg increments and ambulatory DP LOAD limits between 6000 and 12,000 mmHg x beats/min with 1000 mmHg x beats/min increments were used. Then according to these limits, LOAD values of NT and HT subjects have been assessed for daytime, nighttime and 48 hours.

There were significant differences between NT and HT subjects in all the values for both ambulatory PP and DP. Although mean (total, day and night mean) values of HT subjects were higher approximately by 20% than of NT subjects, LOAD values for ambulatory PP in HTs were 33%-415% higher than in NTs (p<0.001). Hypertensive subjects' mean (total, day and night mean) values of DP were by 23%-33% higher than NTs values, but LOAD values for ambulatory DP in hypertensives were approximately 43%-673% higher than in NT subjects (p<0.001).

We showed that although there were significant differences in the 48-hour, daytime and nighttime PP and DP means between NT and HT subjects, these differences became more prominent when possible LOAD limits were used for ambulatory PP and DP, One of these possible ambulatory PP and DP LOAD limits can be used in the clinical settings if a relationship with the end-organ damage will be showed by further studies.