Problem
Sam Smart, a 60-year-old European CEO with a history of minor asthma episodes and a high-stress profession,
Sam was given the advice to change his lifestyle to decrease his blood pressure two years ago when his reading was 145/93 mmHg.
Sam's self-control was never particularly strong, however, and he quickly reverted to his old habits.
- Sam's BP is now 168/115 mmHg at his most recent checkup, and his weight has dramatically grown.
Sam is given an ACE inhibitor called captopril by the doctor.
But a few weeks later Sam returns, complaining of a dry cough and sore throat.
- Instead, prazosin, an alpha-adrenoceptor antagonist, is prescribed by the doctor.
Sam initially struggles with orthostatic hypotension, but after reducing the dose, prazosin is well tolerated and Sam's blood pressure settles at 143/87 mmHg.
A. Explain why more than one measurement of a patient's BP is necessary, and outline factors which might have contributed to the difference observed between Sam's two BP readings.
B. Outline the major features of the renin-angiotensin system and its relationship to BP control.