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Hypotension

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Expect many bleeps about hypotension from concerned nursing staff. It is a useful way to flag up which patients might be unwell. Although defined as below 90 systolic or 60 diastolic, we usually most heavily rely on the systolic on the wards.

The concern is shock - hypotension that leads to hypo-perfusion of organs/tissues resulting in ischaemia.

Consider shock in a patient with any of the following
  • Low BP or tachycardia
  • Confused/less responsive
  • Reduced urine output or new acute kidney injury
  • Raised lactate
When called by the nursing staff
  • Always try to compare their current blood pressure (BP) to their normal. Some patients (young/elderly) may have a normal low BP. Those that are usually hypertensive may be relatively shocked at even normal ranges
  • Those with a high heart rate, are less responsive or have reduced urine output are more concerning
  • Those with a concerning background or other abnormal observations are more concerning
  • It is helpful to request up to date observations, equipment, notes or other things are urgently brought whilst awaiting your arrival
The best way to review if a hypotensive patient is actually unwell is to actually review them systematically. If you are sure they're not unwell, then what to do in this context is at the end.

DR ABCDE approach
As always a DR ABCDE approach is advised with an emergency "crash" call if concerns about responsiveness or airway are found. Ask someone else to put the call out & report back once they've done it - if the patient is that unwell you cannot afford to leave the patient.

Hypoxia or respiratory issues with hypotension suggest a critically unwell patient - strongly consider an emergency call. If you consider putting out a call, you should put the call out.

Focussing on "C" - Assessment & Management of Circulation
Assess the usual features for hypo-perfusion:
  • Take a history if possible of fluid input & output and screen for causes of shock (hypovolaemic, haemorrhagic, anaphylactic, septic, obstructive etc.)
  • Examine the patients capillary refill time & coolness of the limbs
  • Assess their mucous membranes & obtain their obs: BP, pulse and others (tachycardia may not be present in the elderly/those on b blockers)
  • Assess their urine output
  • Take note of their alertness or if they are confused
Consider underlying causes in your examination & context:
  • Can you hear the heart sounds?, is there a new murmur? - these are uncommon but potentially important findings.
  • Is there peripheral oedema? A DVT?
  • Is there marked pallor? are there any obvious signs of blood loss?
  • Is there bleeding? Hypotension & blood loss = Code Red Major Haemorrhage Call (see your own local polices) & an emergency call to 2222.
  • What can you see at the bedside: Can you seen any fluids running? a GTN infusion? A PCA?
Ask the patient how they feel & if they have chest pain

Ask the nurses
  • what is this patient’s background: have they been drinking, have they been vomiting?
  • has the patient been given any medication recently?
  • Is this the patient on a cardiac monitor?
  • Is this patient a post-operative patient?
  • Do they have an epidural?
Treatment of a hypotensive patient
Tip: An emergency trolley is designed to have all the equipment ready for you. Consider using this than wasting time trying to find equipment.

Consider giving oxygen - a shocked patient has hypo-perfusion. Maximising their oxygen with 15L via non-rebreathe mask could optimise the little blood that does perfuse through. Be careful in stroke or myocardial infarction where over-oxygenation can worsen long term outcomes. Ideally titrate to saturations

Establish IV access and bloods - aim for larger cannula “green/grey/orange”/ 16G or higher however a small cannula that's in a patient is better than a large one in the bin.

Take a venous blood gas, FBC, U&Es, CRP, coagulation, group & save and consider blood cultures. The lactate can give an idea of hypo-perfusion and if raised this triggers you to ask for help

Have a low threshold in an emergency setting to consider the intra-osseous (IO) route.

Get a 12 lead ECG - If it’s quicker to attach a nearby monitor, or pads on defibrillator to get a quick rhythm check do this in the first instance, with a view to getting the ECG in a couple of minutes.

The mainstay of treatment in hypotension is to treat the underlying cause.

Consider a fluid challenge:
The most common cause of hypotension on wards is hypovolaemia, a rise in blood pressure with fluid challenge of 250-500mls of crystalloid stat can help you support your diagnosis of hypovolaemia.

Hypotension not responding to a fluid bolus means you should think about other causes, and seek more help.

Consider a leg raise:
This is often less practical on the wards. Firstly, it should not be done manually, rather with a bed which can support the position of the patient lying flat with their feet elevated between 8 and 12 inches above the bed. Older, frail patients may not support the procedure, and it may be difficult to tolerate for patients with not simply low fluid volume causes of hypotension.

Vasopressors:
This is for experienced staff in at least a HDU environment. Patients need to be adequately filled first as they're not so helpful if there's "nothing to squeeze". They are very much a “bridge” treatment to maintain BP while other treatments for the underlying condition are allowed to work.

Consider after care:
Remember that hypotension is usually a sign of illness, therefore we treat the hypotension to prevent deterioration buying us time to find the underlying cause. Walking after a fluid bolus is not helpful - instead seeing whether this is maintained at 15 minute intervals whilst investigating the cause. A catheter (urine output) can help assess response & guide further fluid resuscitation.

Common and important causes:
Have a systematic way of going through the causes of hypotension. One helpful way is thinking about each factor that makes a patient's blood pressure (all those equations from medical school!).

Blood pressure is a factor of what the heart is doing (cardiac output) & the resistance of the vascular system. Cardiac output is a factor of the stroke volume & heart rate. Each of these factors can be looked at systematically.
  • Contractility & HR causing cardiogenic shock
  • Low volume status causing decreased stroke volume & responds well to fluids
  • Decreased vascular resistance by septic or anaphylactic shock - patients may have warm peripheries from vasodilation 
Cardiogenic shock
  • Acute MI
  • Acute Decompensated CCF - secondary to MI, valve rupture, tamponade, fast IV fluids
  • Large pulmonary embolism
  • Tachy or brady arrhythmia -> Use ALS protocols
  • Cardiac tamponade
  • Tension pneumothorax
Low intravascular fluid volumes
  • Nil by mouth patient
  • Patient with high fluid losses from vomiting, diarrhoea, stoma bags, drains
  • Polyuric patient (ie DKA)
Haemorrhage
  • Replace fluid losses with blood where possible.
  • Make rapid definitive plan to stop bleeding - do they need an upper GI endoscopy? Do they need to go to theatre? Do they need interventional radiology input?
Vasodilation +/- increased capillary permeability
  • Sepsis
  • Anaphylaxis
  • Drugs, medications (commonly antihypertensives, diuretics opiates) or an epidural
  • Adrenal insufficiency (reduced vascular tone) - often associated with hypoglycaemia
    • is the patient or have they been on long term steroids?
    • do they have any alert bracelet - Addison's
    • consider as rare but important reversible cause in life threatening hypotension which doesn’t seem to have an obvious cause.
When the patient isn’t unwell
You will often be asked to see a patient on the wards who is mildly hypotensive (systolic 90-119).
In these cases it is very useful to review their recent blood pressures, as well as their blood pressures on previous admissions (easier if your hospital has electronic patient records). It may be that they run with a slightly low blood pressure. If this is the case, their urine output will be normal and they will look well with a normal heart rate.

A blood pressure cuff which is too large for the patient is another cause to consider when a patient is well with a low blood pressure.

From clinical experience, the most common causes for low blood pressure in a relatively well patient are hypovolaemia and medications or drugs.

Written by Dr Yvonne Mitchell Medical SpR, Dr Paul Groves ST7 ICM & Anaesthetics & Dr Akash Doshi CT2

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