Hypotension can be defined as any blood pressure (BP) that is below the normal expected for an individual in a given environment. There is no single numerical cutoff universally accepted as representing hypotension. For example, while <90 mmHg may be considered hypotensive for someone with “normal BP” of 120 mmHg, many healthy young adults will have a resting BP at or potentially below this level and will not be considered hypotensive. As a result, it is difficult to estimate the prevalence. Background history and accompanying clinical findings should be considered, bearing in mind that many common illnesses present atypically in older adults, without characteristic symptoms such as pain.  Hypotension can be the first sign of a serious acute illness (such as MI, sepsis, or GI hemorrhage).  Once acute causes have been excluded, other chronic or recurring causes should then be investigated.
It is essential to ensure that an appropriate cuff size is being used for BP measurements.   Using a cuff that is too small (under-cuffing) may cause overestimation of BP and may further mask a period of hypotension; while use of a cuff that is too large (over-cuffing) can lead to falsely low BP readings with subsequent unwarranted investigation. 
If the patient is not hypotensive at the time of assessment, lying and standing BP recording should be carried out in order to determine if orthostatic hypotension is present. A systolic BP drop of 20 mmHg, or a diastolic BP drop of 10 mmHg occurring within 3 minutes of orthostasis is generally considered to be of significance. 
Hypotension is usually due to:
Decreased effective circulating volume (hypovolemia)
Impaired cardiac output due to heart pump dysfunction (cardiogenic)
Impaired cardiac output due to obstruction to cardiac filling (obstructive)
Impaired peripheral vasoconstriction/distributive change.
In many cases, more than one mechanism is present (e.g., a patient with chronic heart failure who presents with a GI bleed may have evidence of both hypovolemia and reduced cardiac output).
Liaison with nursing staff, with regard to maintenance of patient safety, while investigations are underway is prudent. In particular, patients who are hypotensive in the setting of sepsis may have an accompanying delirium increasing their risk of falls and injury.   It is often difficult to exclude or confirm the presence of shock without close monitoring of vital signs, including BP, heart rate, and urinary output. Therefore, consideration should be given to the most appropriate setting required to monitor, nurse, and medically manage the hypotensive patient.
Department of Healthcare of Older People
Nottingham University Hospitals NHS Trust
Queen’s Medical Centre
FK is an author of a reference cited in this monograph.
Honorary Senior Lecturer at Royal College of Surgeons
Ireland Medical School
Republic of Ireland
AM is an author of a number of references cited in this monograph.
Skagit Valley Hospital
VSP declares that he has no competing interests.
Prince of Wales Hospital
GC declares that he has no competing interests.
Academic Sydney Medical School
University of Sydney
Concord Hospital Centre for Education and Research on Ageing
VN declares that he has no competing interests.
Associate Medical Director
Consultant Emergency Medicine
Guy's and St Thomas' NHS Foundation Trust
Clinical Lead and Consultant
Accident Emergency Medicine
St Thomas' Hospital
AP declares that he has no competing interests.
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