December 17, 2009 — 活動血壓監測須在晚上醒來檢測，也會影響白天的活動，因而會影響血壓下降—血壓值降低一般發生在睡眠時。根據線上發表於12月17日美國腎臟學會臨床期刊(Clinical Journal of the American Society of Nephrology)的研究結果，這使得此項檢查在評估心血管疾病風險的信賴度降低。
VA Merit Review提供研究資金。Agarwal醫師與 Light先生皆宣告沒有相關財務關係。
J Am Soc Nephrol. 線上發表於2009年12月17日。
Ambulatory Blood Pressure Monitoring Disrupts Sleep and Prevents Dipping
By Fran Lowry
Medscape Medical News
December 17, 2009 — Ambulatory blood pressure (BP) monitoring wakes people up at night and reduces their physical activity during the day, thus preventing dipping — the lowering of BP that usually occurs during sleep. This makes the test less reliable in assessing cardiovascular disease (CVD) risk, according to the results of a study published online December 17 in the Clinical Journal of the American Society of Nephrology.
"Ambulatory [BP] monitoring is commonly used to assess the circadian pattern of BP," write Rajiv Agarwal, MD, and Robert Light, BS, from Indiana University and Veterans Affairs Medical Center, Indianapolis. "Circadian BP pattern is influenced by physical activity and sleep cycle. The effect of BP monitoring itself on the level of physical activity and sleep remains unknown. If BP monitoring affects these parameters, then monitoring itself may influence the circadian BP pattern."
The goal of this study was to assess the effect of ambulatory BP monitoring on sleep duration, sleep efficiency, and daytime activity.
The study included 103 veterans with chronic kidney disease (CKD). Most (97%) were men, 83% were white, and their mean body mass index (BMI) was 30 ± 4.7 kg/m2.
The investigators used wrist actigraphy to measure physical activity. After 6 to 7 days of continuous activity monitoring, participants underwent ambulatory BP monitoring in addition to actigraphy.
This procedure was repeated after 1 month.
The researchers found that, when wearing the ambulatory BP monitor, patients spent less time in bed at night (?92 minutes; P < .0001) and slept less (?98 minutes; P < .0001). Patients who were the soundest sleepers at baseline were awakened the most when wearing the monitor. The wake-after-sleep-onset time of the soundest sleepers was 41 minutes at baseline, which increased by 24 minutes (P < .0001) when they were wearing the monitor. In addition, sleep efficiency was reduced by 5% (82% at baseline vs 77% with the monitor; P = .02).
Patients were also less active after they had been wearing the BP monitor. Sedentary time during the day increased by 27 minutes (P = .002).
The sleep disturbance caused by wearing the monitor also increased nondipping (odds ratio, 10.5; P = .008), the authors report.
"The results of our study are relevant for interpretation of ambulatory BP dipping patterns," they write. "Given that [ambulatory BP monitoring] is a cause of sleep disturbance, it is possible that a less intrusive method of [ambulatory BP monitoring] may better assess the prognostic value of [ambulatory BP monitoring]."
The study was limited to mostly older veterans who are generally retired, and therefore less physically active than younger individuals, the authors point out. Because ambulatory BP monitoring was most disruptive in subjects with better sleep characteristics, the results of this study might be more applicable to individuals who are more active and who sleep better, they suggest.
In addition, although morbidly obese patients were excluded from this study, polysomnography was not performed, "therefore we cannot comment on the role of sleep apnea on dipping or lack thereof," the authors write.
Nondipping BP has numerous causes, the authors write in their conclusion. Patients with CKD have the highest prevalence of nondipping, and this has numerous causes, including nocturia, increased physical activity at night, increased sympathetic activation, and sodium sensitivity.
"[Ambulatory BP monitoring]-induced sleep disturbance should now be added to the list of causes of nondipping," the authors conclude.
The study was supported by a grant from the VA Merit Review. Dr. Agarwal and Mr. Light have disclosed no relevant financial relationships.
J Am Soc Nephrol. Published online December 17, 2009.
