Ambulatory blood pressure monitoring [abpm]

1. AMBULATORY BLOOD PRESSURE MONITORING [ ABPM] BY Dr.vasudeva chetty.p Senior resident Dept. of cardiology Svims,tirupati . CAPSULE ON INVESTIGATION

2. INTRODUCTION

3. ABPM , 50 YRS BACK MODERN

4. BP VARIABILITY

5. MEASURES OF BP VARIABILITY,INSTABILITY,REACTIVITY

6. High BP is a trait as opposed to a specific disease and represents a quantitative rather than a qualitative deviation from the norm . Any definition of hypertension is therefore arbitrary . Thus a practical definition of hypertension is ‘ the level of BP at which the benefits of treatment outweigh the costs and hazards’. DAVIDSON’S PRINCIPLES AND PRACTICE OF MEDICINE 21ST ED

7. True BP vs Surrogate Any clinical measurement of blood pressure may be regarded as a surrogate measure for the “TRUE” blood pressure of the patient, which may be defined as the mean level over prolonged periods. Two techniques have been developed to improve the estimate of true blood pressure — ambulatory monitoring and home monitoring (or self-monitoring).

8. ABPM Ambulatory blood pressure (ABP) monitoring involves measuring blood pressure (BP) at regular intervals (usually every 20–30 minutes) over a 24 hour period while patients undergo normal daily activities , including sleep.

9. The portable monitor is worn on a belt connected to a standard cuff on the upper arm . When complete, the device is connected to a computer that prepares a report of the 24 hour, day time, night time, and sleep and awake (if recorded) average systolic and diastolic BP and heart rate.

10. ABPM – measuring Method Ambulatory BP monitors use cuff oscillometry . The cuff is inflated until the pressure occludes flow within the brachial artery. As the pressure is released , blood begins to flow causing fluctuations (oscillations ) in the arterial wall that are detected by the monitor. These oscillations increase in intensity then diminish and cease when blood is flowing normally. The monitor defines the maximal oscillations as mean arterial BP and then uses an algorithm to calculate systolic and diastolic BP .

11. ANALYSIS OF ABPM

12. Reference ‘normal’ ABP values for nonpregnant adults are: 24 hour average <115/75 mmHg ( hypertension threshold 130/80 mmHg ) Day time (awake) <120/80 mmHg (hypertension threshold 135/85 mmHg ) Night time (asleep) <105/65 mmHg (hypertension threshold 120/75 mmHg ).

13. ABPM – Diagnostic Thresholds Category 24hr systolic/diastolic (mm Hg) Daytime (mm Hg) Nighttime (mm Hg) NORMAL <115/75 <120/80 <105/65 HTN >130/80 >135/85 >120/75

14. Ambulatory BP values above ‘normal’ and below thresholds for hypertension are considered ‘high normal’. Night time (sleeping) average systolic and diastolic BP should both be at least 10 % lower than day time (awake) average . Blood pressure load (percentage of time that BP readings exceed hypertension threshold during 24 hours ) should be <20%.

15. Indications for ABPM Suspected white-coat hypertension (including in pregnancy ) Suspected masked hypertension (untreated subject with normal clinic BP and elevated ABP) Suspected nocturnal hypertension or no night time reduction in BP (dipping) Hypertension despite appropriate treatment Patients with a high risk of future cardiovascular events (even if clinic BP is normal) Suspected episodic hypertension.

16. Ambulatory BP monitoring may also be useful for: T itrating antihypertensive therapy B orderline hypertension H ypertension detected early in pregnancy S uspected or confirmed sleep apnoea S yncope or other symptoms suggesting orthostatic Hypotension , where this cannot be demonstrated in the clinic.

17. CLASSIFICATION BASED ON ABPM

18. WHITE COAT HYPERTENSION W hite-coat hypertension is defined as a clinic blood pressure of 140/90 mm Hg or higher on at least three occasions, with at least two sets of measurements of less than 140/90 mm Hg in non-clinic settings, plus the absence of target-organ damage.

19. MASKED HYPERTENSION Defined as a normal clinic blood pressure and a high ambulatory blood pressure. This condition is the reverse of white-coat hypertension. The clinic blood pressure of patients with masked hypertension may underestimate the risk of cardiovascular events .

20. ABPM --PREDICTING CLINICAL OUTCOMES

21. Global Leading Risks for Death Systolic blood pressure > 115 mmHg Global Burden of Disease Study 2010 , Lancet 2012; 380: 2224–60

22. India- Soon Heading Towards Being Hypertension Capital Lancet 2005;365:217-23; JHH 2004;18:73-8 J Assoc Physicians India 2007;55:323-4 At least 1 out of every 5 adult Indians has hypertension Age > 20 yrs Hypertension is responsible for 57% of all stroke deaths and 24% of all CHD deaths in India

23. ABPM --ENDORSEMENT

24. NICE GUIDELINES 2011

25. CONCLUSION Ambulatory monitoring can be regarded as the gold standard for the prediction of risk related to blood pressure, since prognostic studies have shown that it predicts clinical outcome better than conventional blood-pressure measurements. Therefore , a good case can be made for using this technique in all patients in whom hypertension has been newly diagnosed by means of clinic blood-pressure measurements.