Increased Level of Morning Surge in Blood Pressure in Normotensives: ACross-Sectional Study from Pakistan

Abstract

Objective: To determine the mean morning surge (MS) in blood pressure, the frequency of increased morning surge in normotensive subjects, and to compare those with morning surge with those without MS.

Study design: Across-sectional, comparative study.

Place and duration of study: The Department of Medicine, The Aga Khan University Hospital, Karachi, from April 2011 to March 2012.

Methodology: Adult normotensive healthy volunteers aged 35 to 65 years were inducted. Their ambulatory blood pressure (ABP) was measured over a 24-hour period, using digital ambulatory blood pressure monitors. Morning surge was calculated as the average of four readings after waking minus the lowest three nocturnal readings. Increased morning surge was defined as > 11 mm Hg in systolic (SBP) or > 12 mm Hg in diastolic (DBP). Dipping was defined as > 10% dipping in blood pressure.

Results: Eighty-two healthy volunteers were recruited. Their mean age was 36.9 ±1.2 years; 74.4 (61%) were men, and 58.5 (48%) woke up for morning prayers. Mean overall SBPwas 113 ±1.6 mm Hg, overall DBPwas 73.9 ±0.7 mm Hg, and overall heart rate was 75 (10) beats/minute. Mean morning surge was 17.6 ±1.0 mm Hg in SBPand 16.0 ±0.8 mm Hg in DBP. The frequency of increased morning surge was 66 (80.5%) in SBP, and 57 (69%) in DBP. On comparison of participants with normal morning surge and increased morning surge in SBP, there was a significant difference in nondipping status (13.4% in normal vs. 18.3% in increased morning surge, p= 0.001).

Conclusion: Mean morning surge in SBPand DBPare relatively higher in this subset population in a tertiary care center in Pakistan. These values are higher than those reported in the literature.