Clinical Pearls in General Practice - Healthed Newsletter 19 Feb 2015
Ben has been overweight many years but has lost 5 kg in the past 6 months. He’s a non-smoker and drinks alcohol moderately. Given his build, you consider obstructive sleep apnoea but he screens negative. He has mild asthma and today has a heart rate of 90 and a BP of 168/84 with 2+ ankle oedema. A workup for secondary causes of hypertension is negative but his fasting BSL is 6.8, total cholesterol is 5.8, and eGFR 57 is with microalbuminuria, giving him a high absolute risk of cardiovascular disease.
You can’t give Ben a beta blocker because of his asthma and verapamil causes constipation. Before you know it, he’s on felodipine 10 mg, perindopril 10 mg, prazosin 5 mg bd, and hydrochlorothiazide 12.5 mg – but now he’s troubled by leg swelling.
Ben illustrates how a one-size-fits all approach to hypertension in general practice doesn’t work. His management will need to be individualised.
Pertinent issues to consider are:
- the low eGFR 57 of mL/min (chronic kidney disease stage 3a). This is known to be associated with abnormal sodium handling and volume-dependent hypertension.
- his obesity, which is linked to increased salt sensitivity, defined by an increased systolic BP in response to sodium loading and raised sympathetic tone (hyperinsulinaemia increases proximal tubular sodium reabsorption).
The commonest cause by far of resistant hypertension is underuse of diuretics at effective doses. Ben, for example, is getting too many vasodilators, leading to resistance.
A tailored approach for him means reducing his felodipine to 5mg daily and stopping the prazosin.
This should improve his leg swelling but won’t produce any real change in BP, so you will need to replace the hydrochlorothiazide with chlorthalidone 25 mg daily (it’s a stronger diuretic – almost three times strength of hydrochlorothiazide – and has a longer duration of action).
This his GP did, causing the BP to fall to 155/84, with no change in renal function but some mild hypokalaemia requiring one Slow K a day.
Ben has a high resting heart rate, suggesting catecholamine excess, so moxonidine is added. This brings the BP down to 140/78.
Weight loss, a DASH diet, and CPAP after formal sleep studies further reduce the BP to 122/75.
His final medications are:
Source: Dr Jason Kaplan, General Practice Education Day, Adelaide 2014
- perindopril 10mg nocte
- felodipine 5 mg daily
- chlorthalidone 25 mg daily
- moxonidine 200 mcg daily