Daytime hypertension
White-coat hypertension
White-coat effect
Systolic and diastolic hypertension
Isolated systolic hypertension
Isolated diastolic hypertension
Siesta dipping/post-prandial hypotension
Nocturnal hypertension
Dipping:
Nocturnal BP fall >10% of daytime values or
Night/day BP ratio <0.9 and >0.8—normal diurnal BP pattern
Reduced dipping:∗
Nocturnal BP fall from 1 to 10% of daytime values or
Night/day BP ratio <1 and >0.9—reduced diurnal BP pattern
Non-dipping & nocturnal risers:
No reduction or increase in nocturnal BP or
Night/day ratio ≥1—associated with poor cardiovascular risk
Nocturnal risers:
Nocturnal BP greater than daytime BP
Extreme dipping:
Marked nocturnal BP fall >20% of daytime values or
Night/day ratio <0.8—debatable cardiovascular risk
Nocturnal hypertension:
Increased absolute level of night time BP
Associated with increased cardiovascular risk—may indicate
OSA
Morning surge:
Excessive BP elevation rising in morning
Definitions, thresholds and prognostic impact debatable
Short term BP variability
Quantified as 24 h Standard Deviation (SD) or Coefficient of Variation (CV), 24 h Weighted SD or CV, or Average Real Variability of either SBP and DBP
[∗∗The classic definition of non-dipping (Nocturnal BP fall <10% or Night/day ratio >0.9) may be criticized because ‘reduced dipping’ is in effect a form of ‘non-dipping’]
Ambulatory hypotension
Spontaneous, postural, post-prandial and drug-induced hypotensive patterns
There has been a tendency in clinical practice to concentrate on daytime pressures provided by ABPM, as they are thought to be closer to OBPM. However, the association of night-time hypertension with the cardiovascular consequences of hypertension, such as stroke, has focussed the scientific literature on nocturnal hypertensive patterns, such as isolated nocturnal hypertension, and a non-dipping pattern of BP [6, 11, 14–18] (Table 15.1). Indeed, on-going research may show that night-time BP better represents baseline BP measurement, but, at present, it is important to be aware that there may be causes for nocturnal hypertension, such as obstructive sleep apnoea (OSA) [21], and the increased risk of stroke with elevated nocturnal BP, makes it important to assess the response to BP lowering medication during sleep. In some patients, the nocturnal decline in BP may be absent (non-dipping) so that BP does not decrease to at least 10% below daytime BP. In some instances, BP may even rise during sleeping hours to reach levels that are higher than daytime levels (reverse dipping or rising), and these patients are at highest risk. Alternatively, there may be a marked fall in BP during the night window to give the phenomenon of extreme dipping [6, 11, 14]. The magnitude of the rise in BP in the morning—the ‘morning surge’—around the time of awakening may also yield additional prognostic information [7, 11].
Diagnosis of hypotension: Treatment may cause excessive lowering of BP, especially in the frail elderly, when avoiding falls and their resultant morbidity becomes extremely important [6, 11, 22]. Recent evidence suggests that some patients may be adversely affected by marked lowering of nocturnal BP [22]. It is important, therefore, to use ABPM to detect an excessive decrease in BP with medication, especially at night. This is especially relevant in the light of the recent US guidelines for hypertension which advocate a target blood pressure below 130/80mmHg for many patients, including the elderly. [8]
15.2.2 Practical Considerations
Frequency of ABPM: ABPM is beneficial in guiding drug prescribing by identifying patients who need more antihypertensive therapy. In patients with a low risk profile, ABPM might be repeated every few months until control is achieved. If the cardiovascular risk of the patient is high (evidence of target organ damage, previous cardiovascular event, bad family history, or comorbidities, such as diabetes), the need to achieve good BP control becomes more pressing. So once treatment is initiated, it would seem reasonable to repeat ABPM within a few weeks to determine whether adequate reduction has been achieved, but as some individuals will not tolerate frequent ABPM, HBPM is a useful alternative to reduce the need for repeated ABPM [6, 11].
Devices that detect both ABPM and atrial fibrillation (AF): In the elderly, AF now constitutes a mini-epidemic within the larger epidemic of hypertension affecting older age-groups. Given the potential benefits of detecting asymptomatic AF, devices that can combine ABPM with AF detection should be the choice for elderly hypertensive in clinical practice, and manufacturers should be encouraged not only to develop such devices, but to have them validated and evaluated according to internationally accepted standards [23].
15.3 Home Blood Pressure Measurement (HBPM)
15.3.1 Advantages of HBPM
Although HBPM is not as informative as ABPM, the technique provides information that is superior to OBPM and complimentary to ABPM [4, 24]. HBPM provides multiple BP measurements for days, weeks or months away from the artificial office setting and in the usual environment of each individual, thereby allowing thereby a more accurate and representative assessment than with OBPM. HBPM is performed seated at home under relatively stable conditions whereas ABPM is subject to movement, changes in posture and sleep [25, 26]. HBPM allows the detection of white-coat and masked hypertension and is superior to the conventional OBPM in predicting cardiovascular events. HBPM predicts cardiovascular mortality and cardiovascular events after adjusting for OBPM and allows more accurate risk stratification, particularly in patients with masked hypertension [4, 27, 28]. HBPM also allows the assessment of day by day BP variability, which may contribute to outcome prediction [29].
Availability and acceptance by patients: HBPM is widely available in many countries and well accepted by patients [4, 26–28]. Patients prefer HBPM rather than ABPM, particularly for repeated long-term use, as it causes less discomfort and restriction of daily activities and sleep [29]. HBPM increases awareness and patients are motivated to become actively involved in improving BP control [4].
Treatment adjustment: Treated hypertensives who perform HBPM achieve better BP control rates due to improved long-term adherence to drug therapy [30]. Treatment adjustment based on HBPM has been shown to reduce the risk of cardiovascular events [31–33].
Comparison of the features of office, ambulatory and home blood pressure measurements [4]
Feature | Office | Ambulatory | Home |
|---|---|---|---|
Detection of white-coat hypertension | – | ++ | ++ |
Detection of masked hypertension | – | ++ | ++ |
Assessment of night-time BP level and dip | – | ++ | + |
Assessment of morning BP surge | – | ++ | – |
Assessment of morning hypertension | +/– | ++ | ++ |
Assessment of antihypertensive drug action | + | ++ | ++ |
Assessment of duration of drug action | +/– | ++ | + |
Long-term follow-up of hypertension | ++ | +/– | ++ |
Improvement of patients’ compliance | + | – | ++ |
Improvement of hypertension control rate | + | – | ++ |
Reproducibility | – | ++ | ++ |
Prognostic value | + | ++ | ++ |
Availability | ++ | – | ++ |
Cost | – | – | ++ |
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