10. Hypertensive Patient Flashcards
What are the causes of
hypertension
Hypertension is the most common chronic disease in British primary care and almost 50% of people over the age of 65 years have hypertension.
Studies have shown that untreated hypertensive patients are at significantly increased risk of stroke, myocardial infarction, heart failure, renal failure and hypertensive retinopathy.
> Primary (essential) hypertension –
accounts for 90% of cases
> Secondary hypertension –
accounts for 10% of cases.
Secondary causes of hypertension:
Secondary causes of hypertension:
- Renal disease (e.g. renal artery stenosis)
- Endocrine disease (e.g. Conn’s syndrome/phaeochromocytoma)
- Pregnancy-related disease (e.g. pre-eclampsia).
Hypertension can be defined
as a systolic blood pressure (SBP) >140 mmHg
or a diastolic blood pressure (DBP) >90 mmHg.
How can hypertension be
classified?
Table 47.1 Classification of hypertension
Hypertension Systolic pressure Diastolic pressure
- Stage 1 (mild) 140–159 90–99
- Stage 2 (moderate) 160–179 100–109
- Stage 3 (severe) 180–209 110–119
- Stage 4 > 210 > 120
Isolated systolic hypertension
> 150 < 90
What types of medication might a hypertensive patient be taking?
In the primary care setting,
basic treatment for primary hypertension may
include advice about lifestyle changes such as weight reduction and increased exercise and dietary changes such as reducing salt intake.
The following classes of antihypertensive medication may also be prescribed:
> Diuretics, e.g. bendroflumethiazide
> β-adrenoceptor antagonists, e.g. atenolol
> Angiotensin-converting enzyme inhibitors, e.g. ramipril
> Angiotensin II inhibitors, e.g. losartan
> Calcium channel antagonists, e.g. amlodipine
> α-adrenoceptor antagonists, e.g. doxazosin
> Potassium channel activators, e.g. nicorandil
Discuss the peri-operative
management of a hypertensive
patient presenting for surgery.
Pre-operative assessment:
Pre-operative assessment:
> Confirm the diagnosis of hypertension
and establish current treatment.
> Confirm the efficacy of treatment,
or establish if modification of the
antihypertensive regimen is required,
e.g. dose alteration, drug class switch or addition.
> If hypertension is severe
(i.e. stage 3 – SBP >180 or DBP >110),
this should be treated before elective surgery.
> Search for end-organ damage throughout the history, examination and investigations.
It is important to establish associated co-morbidity and
assess cardio-respiratory performance, e.g. exercise tolerance.
> Investigations may include:
- ECG (look for left ventricular hypertrophy or strain pattern)
- Electrolytes (diuretic-induced hypokalaemia or elevated creatinine secondary to ACE inhibitors)
Pre-operative preparation:
> Continue all antihypertensive medications up to and including the morning of surgery except for
ACE inhibitors, which should be omitted
for 24 hours prior to surgery, as they are associated with severe refractory intra-operative hypotension.
Potential intra-operative problems:
The hypertensive patient is at increased peri-operative risk and the following problems may be encountered intra-operatively:
> Labile blood pressure – lability is more common at certain points such as induction, intubation, start of surgery, extubation and post-operatively if pain is uncontrolled.
> Remember that a hypertrophied left ventricle is at severe risk of peri-operative sub-endocardial myocardial ischaemia.
This may occur if there is a fall in coronary perfusion pressure or coronary filling time, and so low BP and tachycardia should be avoided.
> Vasoactive agents should be administered cautiously to hypertensive patients as the response may be exaggerated, particularly if regular
antihypertensive medication has been given.
> Organs that autoregulate their blood supply (e.g. cerebral circulation) will have a right shift in the autoregulation curve, which may result in organ blood flow being severely compromised if a hypertensive patient becomes hypotensive.
> Left ventricular diastolic dysfunction is common in hypertensive patients.
> Fluid balance is extremely important, as large fluid shifts are not well tolerated; maintenance of intravascular volume is vital.
Monitoring:
> Invasive blood pressure monitoring with an arterial line should be used for hypertensive patients undergoing major surgery and should be
considered on an individual patient basis for other types of surgery.
Post-operatively:
> Rebound hypertension is a common occurrence.
Myocardial work is increased by such elevations in blood pressure,
care must be taken not to cause a precipitous fall in blood pressure by rapid administration
of further antihypertensives,
as this may lead to hypotensive ischaemia.
> A full assessment of the patient in the post-anaesthesia care unit should be performed, looking for potential causes of rebound hypertension
(e.g. pain, hypoxia, hypercarbia, fluid overload, hypothermia).
Only once these have been dealt with should cautious administration of an antihypertensive be considered.
> Supplemental oxygen should be considered in all hypertensive patients.
When would you cancel a
hypertensive patient’s operation?
This is not a straightforward question because it requires a risk–benefit analysis,
focusing on the urgency of the surgery,
the severity of the hypertension and
individual patient factors such
as the extent and severity of
end-organ damage and associated co-morbidities.
There is considerable difference of opinion as to what the threshold blood pressure is for cancelling elective cases in order to optimise treatment.
You may, however, be pushed by the examiners
to give examples of what types of patient you might cancel, so this list of scenarios may be a sensible guide:
> Severe hypertension (DBP >110 mmHg)/Elective surgery
• Cancel – treat for at least 1 month prior to reassessment.
> Moderate hypertension (DBP 100–109 mmHg)/End-organ damage/ Elective surgery
• Cancel – treat for at least 1 month prior to reassessment.
> Moderate hypertension (DBP 100–109 mmHg)/No end-organ damage/ Elective surgery
• Cancel – treat for 5–7 days then reassess.
> Mild hypertension (DBP 90–99 mmHg)/Elective surgery
• Consider peri-operative β-blocker if not contraindicated (e.g. administered 30 minutes prior to surgery) and proceed.
