ESSENTIAL HYPERTENSION 2: Treatment and Monitoring Update
By Kennedy, Susan
This two-part series on essential hypertension highlights recent changes in the management of patients with sustained raised blood pressure (BP). This article focuses on lifestyle changes to lower blood pressure, drug treatment and monitoring requirements, and the role of the nurse in management.
Lifestyle methods to lower blood pressure
Reducing weight in the overweight and obese, reducing sodium salt intake, increasing fruit and vegetable consumption and increasing aerobic exercise have been shown to reduce blood pressure (BP).1 Stopping smoking will reduce cardiovascular risk significantly.2 These lifestyle changes should be promoted at diagnosis and during pharmacological treatment as they may reduce the need for high doses and/or multiple drug regimens.
Weight reduction
The higher the body mass index (BMI), the greater the risk of hypertension. An appropriate cuff, with a bladder large enough to cover 80 per cent of the upper arm, is needed to measure BP, so a larger cuff size should be available. An appleshaped body confers a higher risk of cardiovascular disease (CVD) as a result of insulin resistance syndrome, a complex of conditions including hypertension, glucose intolerance and raised lipid profile. Those at risk in the Caucasian population have a waist circumference >102 cm (40 in) in men and >88 cm (34.5 in) in women. In the South Asian population the equivalent risk is >90 cm (35.5 in) in men and >80 cm (31.5 in) in women. By losing 5-10 per cent of total body weight all people can reduce CVD risk. Sustained weight loss of 1 kg can lower BP by 1 mmHg.
Figure 1. The plate method to estimate diet
Diet
Initial dietary assessment allows advice to be tailored to the individual and includes:
* Using the plate method (see Figure 1);
* Completing a food diary;
* Discussing food preparation;
* Identifying stages of behaviour change;
* Considering cultural issues.
The Dietary Approaches to Stop Hypertension (DASH) study found that diet could lower BP as much as taking an antihypertensive medicine/ When compared with a typical USA diet, the overall diet that led to a lower BP was:
* Lower in sodium intake;
* Lower in total fat, saturated fat and cholesterol;
* Higher in fibre;
* Included lots of vegetables and fruit (as much as seven portions), whole grains and low-fat dairy products;
* Moderate in meat, fish and poultry;
* Included nuts, seeds and legumes several times a week.
Salt (sodium chloride) intake should be <6 g/day for adults. This is equivalent to one teaspoon of salt or <2.5 g of sodium. If the nutrition panel on a 500 g ready prepared meal states there is 0.5 g sodium/ 100 g then the total daily salt intake is contained in this one meal. Other forms of sodium are found in flavour enhancers and preservatives, such as monosodium glutamate and sodium bicarbonate. Foods considered to be low in salt will display <0.1 g of sodium/ 100 g in the nutrition panel. Certain foods commonly high in salt include many packet breakfast cereals, tinned products, bought sauces and condiments, crisps, processed meats and hard cheeses.
A popular alternative is to use potassium salt such as LoSaIt. However, patients on ACE inhibitors should avoid potassium supplementation in medication and salt substitutes as this can result in hyperkalaemia, that is, serum potassium >5.5 mmol/1.4
Increasing fruit and vegetables to at least five and if possible seven portions per day can lower blood pressure as part of a healthy diet. A portion is 80 g, which is equivalent to a dessert bowl of lettuce, three tablespoons of vegetables, two medium tomatoes, one medium banana or half a mango.
Functional foods have been asserted to reduce the risk of heart disease, in particular probiotics, which claim to lower cholesterol and BP.5 The most recent addition is a dairy drink containing peptides that ‘actively helps control blood pressure’. These products must be consumed regularly, in the correct quantity and as part of a healthy diet to achieve the producers’ claims. Functional food studies used secondary endpoints such as lowered BP, not primary endpoints such as reduced stroke rates, unlike the major studies used in guidelines. There are also financial implications for the patient.
Alcohol
Individuals taking more than 21 units for a man and 14 units for a woman during one week and/or binge drinking have a greater CVD risk. Where alcohol has become an addiction then specialist advice should be offered. Otherwise brief motivational interviewing is recommended to support patients to take no more than three units/ day for men and two units/day for women.
Activity
Regular activity equivalent to a daily 20-30 minute brisk walk is beneficial to health.6
Figure 2. The AB/CD algorithm: British Hypertension Society recommendations for combining blood pressure-lowering drugs
Individuals who can accumulate 30 minutes of moderate aerobic activity on at least five days/week can potentially reduce resting systolic blood pressure by 6-13 mmHg and diastolic by 9-12 mmHg. During exercise there is a normal increase in systolic BP. Over time, exercising improves cardiac function and lowers BP at rest. Moderate intensity exercise includes:
* Washing and waxing a car for 45-60 minutes;
* Walking 1.75 miles in 35 minutes (20 min/mile);
* Dancing fast (social) for 30 minutes;
* Cycling five miles in 30 minutes;
* Water aerobics for 30 minutes;
* Stair walking for 15 minutes.
Pharmaceutical treatment
Antihypertensive treatment significantly reduces CVD risk.7 When medication is required the aim is to achieve a target BP of less than 140/85 mmHg (or 130/80 mmHg in patients with diabetes and/or renal disease). This may mean taking maximum doses of three or more classes of antihypertensive medication. Where target BPs are not achieved with such regimens, compliance should be considered before referring to a specialist for investigation of secondary causes and white coat hypertension.
The first-line drugs recommended for hypertension vary between guidelines. The British Hypertension Society (BHS) adopted the AB/ CD algorithm (shown in Figure 2)8 while the National Institute for Health and Clinical Excellence (NICE) guideline recommends low-dose diuretics or betablockers for all hypertensive patients. The recent trial, ASCOT-BPLA, provided information on the use of betablockers and thiazides versus calcium antagonists and angiotensin converting enzyme (ACE) inhibitors in combination to control BP. The results showed better BP control in the ACE inhibitor and calcium antagonist group with greater reductions in stroke (23 per cent), cardiovascular events and procedures (16 per cent), and new onset diabetes (30 per cent). Subsequently, NICE and the BHS have formed an expert group to review the NICE hypertension guideline.
Classes of hypertension drugs
Diuretics are grouped into thiazide, loop or potassium sparing. Low-dose thiazide diuretics are first choice in essential hypertension. Thiazide diuretics can lower plasma potassium placing patients at risk of cardiac arrhythmia. Raised urate can cause gout. Erectile dysfunction can be an adverse effect in men. Due to these metabolic effects annual blood monitoring is recommended.
Beta-blockers are cardioprotective because they inhibit the rate and force of cardiac contraction. Adverse effects include lethargy, reduction of exercise tolerance (slowing of heart rate), bronchospasm, Raynaud’s disease and impotence. Beta-blockers should be avoided in asthma, bradycardia and heart block, and used with caution in heart failure.
Calcium antagonists are in two main types. The dihydropyridines, such as amlodipine and nifedipine, have a greater effect on vascular smooth muscle resulting in adverse effects as a result of vasodilation, such as headache and ankle swelling. Taking grapefruit with calcium antagonists increases the risk of hypotension and raised heart rate.9 The nondihydropyridines, such as diltiazem and verapamil, are rate limiting and should not be used with beta- blockers.
ACE inhibitors act by vasodilating arterioles, reducing sodium and water retention, and relaxing the sympathetic nervous system. Adverse effects include dry, irritating cough (in 10 per cent of men and 20 per cent of women), deterioration of renal function in bilateral renal artery stenosis, first-dose hypotension and, very rarely, angioneurotic oedema. A low starting dose is recommended to avoid either hypotension or rare renal failure. Renal function should be checked within 10 days prior to making a dose increase.
Angiotensin II receptor blockers (ARBs) do not increase bradykinin levels and so do not produce the dry cough seen with ACE inhibitors. Similar precautions need to be taken for ARBs as for ACE inhibitors.
Alpha-receptor antagonists, such as doxazosin, terazosin and prazosin, require careful dosing to avoid postural hypotension.
Patient information
Information about dosage and the possible adverse effects of treatment should be provided for patients. The Blood Pressure Association is a good resource for patients (see its website for more details: www.bpassoc.org.uk).
Monitoring hypertension
Appointments at four weekly intervals are suggested until BP is controlled. Once BP and other risk factors reach target, six- monthly checks are part of the GMS quality outcomes framework.10 At a review:
* Check BP is controlled to 140/85 mmHg or less;
* Monitor end organ damage;
* Review treatments and compliance;
* Re-me\asure other cardiovascular risk factors;
* Collect information for audit.
A key role for nurses
Nurses effectively lead hypertension clinics provided they have the necessary knowledge and skills.
A practice nurse survey found that, although their level of autonomy varied, approximately half of all nurse chronic disease management visits included BP checks, confirming the important role for nurses in this area.” In a systematic review of nursing in hypertension studies, nurses were as effective at lowering BP as physicians.12 Nurses provided information, educated in self- measurement of BP, gave advice about diet, controlled the intake of medicine and laboratory tests, and encouraged patients. A study comparing nurses and doctors managing hypertensive patients found:
* Average longer conversations with nurses than doctors;
* Nurses talked to patients about other risk factors more often than doctors;
* Doctor consultations focused on medication more;
* Patients raised more new topics with nurses.13
Communication skills were, therefore, the distinctive feature of the nurse’s role.
Length of appointment will depend on the patient, but 30 minutes for an initial cardiovascular assessment and 15 minutes for an annual review is a minimum. At appointments nurses should consider the factors that influence behaviour:
* Knowledge
* Health beliefs
* Readiness to change
* Perception of beliefs
* Social and cultural factors
* Relationship with clinician.
Conclusion
Hypertension is well suited to management by a multidisciplinary team. The nurse’s role includes:
* Ensuring all patients with hypertension are known;
* Providing lifestyle advice
* Checking regular follow-up;
* Reviewing blood pressure is controlled to target;
* Keeping information documented and accessible for other staff and for audit.
Hypertension is a common chronic condition and community nurses have an important role to play in optimising the quality of care provided in the UK.
Next month’s Clinical Update will focus on autistic spectrum disorders.
Approximately half of all nurse chronic disease management visits included blood pressure checks
REFERENCES
1 Stamler J, Farinaro E, Mojonnier LM et al. Prevention and control of hypertension by nutritionalhygenic means. Long-term experience of the Chicago Coronary Prevention Evaluation Programme. Journal of the American Medical Association 1980;243: 1819-1823.
2 Doll R. One for the heart. British Medical Journal 1997; 315: 1664-1668.
3 Sacks FM, Svetkey LP, Vollmer WM et al. DASH-Sodium Collaborative Research Group. Effects on blood pressure of reduced dietary sodium and the dietary approaches to stop hypertension (DASH) diet. New England Journal of Medicine 2001; 344:3-10.
4 Ray K, Dorman S, Watson R. Severe hyperkalaemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction. Journal of Human Hypertension 1999; 13: 717-720.
5 Guarner F1 Malagelada JR. Gut flora in health and disease. Lancet 2003; 361, 9356: 512-519.
6 Shaper AG, Wannamethee G. Physical activity and stroke in middle aged British men. British Heart Journal 1991; 66: 384-394.
7 Wingfield D, Pierce M, Feher M. Blood pressure measurement in the community: do guidelines help? Journal of Human Hypertension 1996; 10: 805-809.
8 Williams B, Poulter NR, BrownMJ et al. Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, 2004 – BHS IV. Journal of Human Hypertension 2004; 18: 139-185.
9 Bailey DG, Spence JD1 Munoz C, Arnold JM. Interaction of citrus juices with felodipine and nifedipine. Lancet 1991; 337: 268-269.
10 Investing in General Practice – the new General Medical Services contract. London: NHS Confederation/BMA, 2003. Available at: www.nhsconfed.org/gmscontract (accessed 11 January 2005).
11 Eve R1 Waller i, Gerrish K. Chronic disease management. Practice Nurse 2001; 14 September: 48-51.
12 Bengsten A, Drevenhorn E. The nurses’ role and skills in hypertension care: a review. Clinical Nurse Specialist 2003; 17, 5: 260-268.
13 Aminoff UB, Kjellgren KI. The nurse – a resource in hypertension care. Journal of Advanced Nursing 2001; 35, 4: 582- 589.
Susan Kennedy MSc RGN SCM DN
Practice nurse
Ferness Surgery, Glasgow
Copyright TG Scott & Son Ltd. Feb 2006