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 cut-off 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.[1]Gibson SJ, Helme RD. Age-related differences in pain perception and report. Clin Geriatr Med. 2001 Aug;17(3):433-56, v-vi.
http://www.ncbi.nlm.nih.gov/pubmed/11459714?tool=bestpractice.com
Hypotension can be the first sign of a serious acute illness (such as myocardial infarction, sepsis, or gastrointestinal haemorrhage).[2]Sigurdsson E, Thorgeirsson G, Sigvaldason N. Unrecognised myocardial infarction: epidemiology, clinical characteristics and the prognostic role of angina prectoris. The Reykjavik Study. Ann Intern Med. 1995 Jan 15;122(2):96-102.
http://www.ncbi.nlm.nih.gov/pubmed/7993002?tool=bestpractice.com
Once acute causes have been excluded, other chronic or recurring causes should then be investigated.
Blood pressure measurement
It is essential to use an appropriate cuff size for BP measurements.[3]Williams B, Mancia G, Spiering W, et al. 2018 Practice guidelines for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. Blood Press. 2018 Dec;27(6):314-40.
http://www.ncbi.nlm.nih.gov/pubmed/30380928?tool=bestpractice.com
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.[3]Williams B, Mancia G, Spiering W, et al. 2018 Practice guidelines for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. Blood Press. 2018 Dec;27(6):314-40.
http://www.ncbi.nlm.nih.gov/pubmed/30380928?tool=bestpractice.com
If the patient is not hypotensive at the time of assessment, lying and standing BP recordings 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.[4]Freeman R, Wieling W, Axelrod FB, et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clin Auton Res. 2011 Apr;21(2):69-72.
http://www.ncbi.nlm.nih.gov/pubmed/21431947?tool=bestpractice.com
Most automatic sphygmomanometers overestimate BP in patients with atrial fibrillation, because they record the highest systolic pressure rather than an average over several cardiac cycles. Palpate the patient’s pulse to exclude arrhythmia before using an automatic sphygmomanometer.[3]Williams B, Mancia G, Spiering W, et al. 2018 Practice guidelines for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. Blood Press. 2018 Dec;27(6):314-40.
http://www.ncbi.nlm.nih.gov/pubmed/30380928?tool=bestpractice.com
Pathophysiology
BP is determined by cardiac output (the product of heart rate and stroke volume) and total systemic vascular resistance. Hypotension occurs when the cardiac output decreases and/or the systemic vascular resistance decreases. Hypotension is usually due to:
Decreased effective circulating volume (hypovolaemia)
Impaired cardiac output due to heart pump dysfunction (cardiogenic)
Impaired cardiac output due to obstruction to cardiac filling (obstructive)
In many cases, more than one mechanism is present (e.g., a patient with chronic heart failure who presents with a gastrointestinal bleed may have evidence of both hypovolaemia and reduced cardiac output).
Initial management considerations
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.[5]Haerlein J, Dassen T, Halfens RJ, et al. Fall risk factors in older people with dementia or cognitive impairment: a systematic review. J Adv Nurs. 2009 May;65(5):922-33.
http://www.ncbi.nlm.nih.gov/pubmed/19291191?tool=bestpractice.com
[6]Corsinovi L, Bo M, Ricauda- Aimonino N, et al. Outcomes in elderly patients admitted to an acute geriatric unit. Arch Gerontol Geriatr. 2009 Jul-Aug;49(1):142-5.
http://www.ncbi.nlm.nih.gov/pubmed/18674824?tool=bestpractice.com
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.
