【Yao Anesthesiology】Hypertension (3)

C.
Intraoperative management

1.
How is this patient monitored?

2.
What are the goals of anesthesia for hypertensive patients?

3.
How to perform anesthesia induction for hypertensive patients?

4.
How does endotracheal intubation cause high blood pressure?

5.
What is the effect on the left ventricular ejection fraction during and immediately after intubation?

6.
How to prevent hypertension and tachycardia during intubation?

7.
After induction and intubation, the blood pressure drops to 70/40mmHg, what will you do?

8.
What drugs will be selected for anesthesia maintenance? Why?

9.
How is fluid therapy given to patients with high blood pressure?

10.
How will you deal with the patient's blood pressure rising to 220/120mmHg during surgery?

11.
How to prevent hypertension during extubation and awakening?

12.
Would you consider regional anesthesia for this patient?

D.
Postoperative management

1.
How should patients deal with the blood pressure in the recovery room after surgery when their blood pressure reaches 210/110mmHg

C.
2.
What are the goals of anesthesia for patients with hypertension?

The goal of anesthesia is to minimize fluctuations in blood pressure caused by anesthesia and surgical stimulation in order to prevent the following complications:

●Myocardial ischemia: due to tachycardia or, less commonly, hypertension or hypotension
.
● Hypoperfusion
of the brain due to hypotension.

●Intracerebral hemorrhage and hypertensive encephalopathy — Caused by
embolic stroke due to hypertension or rupture of plaque of local vascular, aorta, or neck vessels.

● Renal failure
due to renal hypoperfusion.

It is highly recommended that diastolic blood pressure be lowered with particular attention to diastolic blood pressure
.
What is not optimistic is that current clinical practice is mainly centered around reducing systolic blood pressure, and does not focus on diastolic blood pressure
.
This is particularly tricky
in most older patients with ISH and/or PPH.
In both subtypes of hypertension, already low diastolic blood pressure drops lower—more likely to cause myocardial hypoperfusion and ischemia
.

Recently, Lee et al.
proposed that patients with increased pulse pressure have an increased risk of thrombosis, marked by increased
levels of D-dimer, hemophilia-like factor, and platelet activator.
These patients often have extensive arteriosclerotic lesions of the aorta, carotid, and renal arteries, which are also common
in patients with ISH.
Finally, it is important to carefully manage the hemodynamic response of hypertensive patients to
nociceptive stimuli such as intubation, surgical excision, and awakening.

C.
3.
How is anesthesia induction performed in patients with hypertension?

When the patient is pre-oxidized, slowly give 7~8μg/kg fentanyl to sleep, and then, give pentathiobarbital 50mg or propofol 30~50mg until consciousness disappears, and then give succinylcholine 1mg/kg or non-depolarizing muscle relaxant to complete endotracheal intubation
.

All anesthetic drugs may be used
except ketamine, which produces significant hypertension and tachycardia.
Nevertheless, inhalation anesthetics should be used with caution to reduce hypertension and tachycardia, as both vasodilation and cardiodepression can increase the incidence of
hypotension.

C.
4.
How does endotracheal intubation cause hypertension?

Translaryngeal endotracheal intubation stimulates receptors in the larynx and trachea, resulting in a significant increase in sympathomimetic amine products, and sympathetic stimulation leads to tachycardia and increased
blood pressure.
In patients with normal blood pressure, the increase in blood pressure is about 20~25mmHg; It is higher
in patients with hypertension.

C.
5.
What are the changes in the left ventricular ejection fraction during and immediately after intubation?

Tachycardia and hypertension are often associated with intubation during and immediately after intubation, and the ejection fraction of the left ventricle is reduced
.
This is particularly pronounced
in patients with coronary heart disease.
Nevertheless, this hemodynamic disorder can be expected and treated
with β blockers, sedatives, intravenous instillations of hypnotics, and inhalers.

C.
6.
How can hypertension and tachycardia be prevented during intubation?

The increase in blood pressure and heart rate occurs approximately 14 seconds after the start of laryngoscopic operation and reaches a maximum 30~45 seconds after direct laryngoscopic operation.

If possible, laryngoscopy should be completed in 15 seconds or less to minimize
blood pressure elevation.
Fentanyl 7~8μg/kg and inducible doses of pentathiobarbital or propofol at the time of intubation can inhibit the cardiovascular response
to endotracheal intubation.
Other methods are described below

● Lidocaine, 1.
5mg/kg 2
minutes before intubation.

● Esmolol, when administered to 2mg/kg, can smoothly fight hypertension and tachycardia caused by intubation, the drug is easy to titrate and will not aggravate the hypotensive response after intubation, because its action period is short
.

● Labetalol, 0.
15~0.
45mg/kg is equivalent to esmolol 1.
5~4.
5mg/kg, used to reduce hemodynamic response
.
The venous half-lives of esmolol and labetalol are 9 minutes and 5 hours
, respectively.
In addition, labetalol has a small effect on heart rate and acts on α receptors, which has a similar
effect to vasodilators.

● Nicardipine, intravenous administration of 1mg nicardipine 2 minutes before intubation can maintain intraoperative hemodynamic stability
.
Doses of 0.
015 mg/kg and 0.
03 mg/kg during awakening and extubation can reduce blood pressure without effect
on heart rate.
Higher doses (0.
03 mg/kg) of nicardipine produce a stronger blood pressure control effect
.

It is worth noting that the doses of all the drugs mentioned above are single doses
.
If multiple drugs (including narcotic drugs) are used in combination, then the dose should be relatively reduced
.
Otherwise, severe hypotensive reactions
occur.

C.
7.
After induction and intubation, your blood pressure drops to 70/40mmHg, what will you do?

The hypotensive response after anesthesia induction is usually the result of
a combination of vasodilation, volume depletion, and cardiovascular depression.
Inducers such as pentathiobarbital, propofol, diazepam, midazolam, moderate to high doses of sedatives, and potent inhalation anesthetics can cause vasodilation
.
Due to long-term vasoconstriction and (or) diuretic use, patients with hypertension have relatively little
blood volume.
Preoperative bowel preparation and fasting water also further exacerbate hypovolemia
.
Barbiturates, benzodiazepines, and inhalation anesthetics can cause mild to moderate cardiovascular depression
.

Hypotension after anesthesia induction is usually easy to correct, and vasoconstrictors such as ephedrine 5~10mg or phenylephrine 0.
1mg
are given at the same time.

C.
8.
Which drugs are selected for anesthesia maintenance? Why?

In patients with hypertension, no particular anesthesia technique or specific combination of drugs has been shown to be superior to other methods
.
Potent inhalation anesthetics or sedatives should be adjusted to appropriate doses to depress the central nervous system to ideal levels while continuously regulating blood pressure
.

Sedatives and nitrous oxide provide better stability of blood pressure during anesthesia, but intraoperative hypertension is difficult to control
with moderate doses of sedatives.
Higher doses of sedatives are also discouraged for early extubation
.
Similarly, the use of nitrous oxide in open cholecystectomy is controversial because it tends to increase flatulence, and its severity is closely related
to the concentration of nitrous oxide and the duration of use.
This is less appropriate in laparoscopic cholecystectomy, as mechanical pressure injecting gas into the abdominal cavity counteracts the dilating properties of nitrous oxide (see Chapter 26, Question C.
8).

Powerful inhalation anesthetics provide better control of hypertension but are less stable
.
Isoflurane, diflurane, and sevoflurane have a stronger peripheral vasodilator effect while having a weaker
cardiostatic effect.

C.
9.
How to administer fluid therapy for patients with hypertension

Patients with essential hypertension usually result in volume depletion
due to vasoconstriction and diuretic use.
Fluid replacement should be given prior to anesthesia induction to minimize
the sharp drop in blood pressure that is common in hypertensive patients.
Nevertheless, excessive fluid replacement should also be avoided, as postoperative hypertension can lead to postoperative hypertension
after the vasodilating effect of postoperative anesthesia wears off.
Therefore, it is important
to carefully evaluate fluid replacement and loss.
Both urinary catheters and central venous pressure monitoring can be used to guide fluid therapy
.

As mentioned above, the presence of left ventricular hypertrophy (LVH) in hypertensive patients shifts the left ventricular compliance curve up and to the left, resulting in higher diastolic blood pressure
at the same ventricular volume compared with nonhypertrophic ventricles.
In these patients with pulmonary artery catheterization, higher pulmonary artery wedge pressure (PAOP) (sometimes > 20 mmHg) is necessary to achieve normal volume, and cardiac output
must be monitored frequently when fluid volume is required.

C.
10.
How will you deal with the patient's blood pressure rising to 220/120mmHg during surgery?

The methods of control of intraoperative hypertension are listed
in Table 10.
4.
Severe intraoperative hypertension is more common in insufficient depth of anesthesia
.
Insufficiency of sensory afferents during surgical procedures increases the breakdown and release of sympathetic amines, leading to hypertension and tachycardia
.
If a potent inhalation anesthetic is applied, the depth of anesthesia can be increased by deepening the concentration of
the inhalation anesthetic.
Sedatives alone may not control the rise in blood pressure, and a potent inhalation anesthetic
should be used instead.

5 mg hydralazine is gradually increased to make blood pressure drop steadily, and less so that blood pressure drops too much
.
The onset time is 10~15 minutes, which can last for 1~2 hours
.

5~10mg labetalol is effective
in controlling hypertension and tachycardia.
The use of β blockers after a significant increase in blood pressure is most meaningful because the pharmacological effect of these drugs is to directly antagonize catecholamines
.
Although other drugs can lower blood pressure, it is likely that norepinephrine and epinephrine continue to act on the receptor site, causing microcirculatory vasoconstriction to affect tissue perfusion
.
This view also explains the extensive anti-ischemic effect of perioperative β blockers on the heart, brain, and
kidneys.

Continuous intravenous infusion of nicardipine, nitroprusside, nitroglycerin, and direct arterial vasodilators is rarely required during anesthesia to control hypertension
.

C.
11.
How can hypertension be prevented during extubation and awakening?

Since the patient is awake after surgery, antihypertensive drugs may be considered during extubation and awakening.

Many drugs or combinations of drugs are effective, including intravenous lidocaine, esmolol, labetalol, verapamil, or dilti 2 minutes before extubation
.
If blood pressure exceeds ideal levels after extubation, titration may be considered to control blood pressure
.

C.
12.
Would you consider regional anesthesia for this patient?

Of course, regional anesthesia can avoid significant increases in sympathetic tone and significant changes
in hemodynamics during intubation and extubation.
Subarachnoid block or epidural can be used for low-lying abdominal surgery
.
For cholecystectomy, high regional anesthesia is required, which may suppress respiratory function
.
At the same time, longer surgeries can induce anxiety and nervousness, which can lead to high blood pressure and tachycardia
.

D.
Postoperative management

D.
1.
How should patients have a blood pressure of 210/110mmHg in the recovery room after surgery?

The management of postoperative hypertension depends on the etiology, clinical symptoms, and level of
hypertension.
First of all, the cause of hypertension should be identified and treated
accordingly.
High blood pressure itself should also be treated
with antihypertensive drugs.
Postoperative hypertension causes include pain, wake-up agitation, hypoxemia, hypercapnia, irritation of endotracheal intubation, bladder distention, hypothermia, relatively high blood volume due to large intraoperative fluid replacement, and withdrawal symptoms
after long-term drug discontinuation.
The most common cause of postoperative hypertension is painful
incision.
When the patient is awake, painful stimuli induce catecholamine release
.
In many hypertensive patients, the extreme instability of blood pressure makes the release of catecholamines increase rapidly and is not easy to control
.
Depending on the cause of high blood pressure, intravenous analgesics, blood pressure medications, and diuretics
are used.
If postoperative tachycardia and hypertension occur together, calcium-channel blockers such as verapamil, diltiola, or nicardipine and β blockers such as propranolol, esmolol, labetalol, or metoprolol are good choices
.
Hypertension due to pain can be prevented and alleviated
by local injection of long-acting anesthetic drugs around the wound or by performing regional nerve blocks.

Link to previous article

【Yao's Anesthesiology】Reading Notes on Hypertension (1).

【Yao Anesthesiology】Hypertension (2)