According to the common international criteria (adopted in 1999), arterial hypertension (AH) is a condition in which systolic blood pressure is 140 mm Hg. Art. or higher, and / or diastolic blood pressure of 90 mm Hg. Art. or higher in people who are currently not receiving antihypertensive treatment.
Depending on the level of blood pressure, the degrees of arterial hypertension are distinguished, which are described below.
Degrees of hypertension – Systolic blood pressure, mm Hg. Art. – Diastolic blood pressure, mm Hg. Art.
1 degree – 140-159 – 90-99
2 degree – 160-179 – 100-109
3 degree – more than 180 – more than 110
Perioperative arterial hypertension
Arterial hypertension is very often found, especially among patients of not old age – more than 40%. AH of the first or second degree slightly increases the risk of cardiovascular complications during anesthesia. Higher values of pressure are accompanied by saying that there may be more complications and they are more serious.
In planned patients with AH of grade 3 (systolic pressure> 180 mm Hg and / or DBP> 110 mm Hg), one should consider the possibility of delaying the intervention to optimize the therapy of hypertension.
Drugs that are used to treat hypertension, and means for anesthesia, with the interaction can lead to the development of resistant hypotension and other intraoperative complications. The criterion for correctly selected medical hypotensive therapy for routine surgical intervention is the normal age level of arterial pressure in a patient with a deviation of ± 20%.
Important times for the safe conduct of anesthesia are also the time during which BP normalized. The patient’s body needs a lot of time to adapt to a lower level of blood pressure. For example, a patient with hypertension of the third degree, using intravenous vasodilators, can “normalize” the pressure within a few tens of minutes. And if such a patient begins to carry out, for example, epidural anesthesia, then the likelihood of developing a stroke, uncontrolled hypotension, a heart attack will increase rapidly.
Doctors should pay attention to the fact that it is unacceptable to carry out an intensive correction of arterial hypertension of the 2nd-3rd degree before the planned operation for one or two days. And even more so – for 3-4 hours. It is necessary, at least, two or three weeks to choose the best antihypertensive therapy. We also note that the standards for the treatment of hypertension are allocated for this purpose for at least a month (30 days).
The question is raised, whether it is necessary to interrupt reception of antihypertensive drugs before the operation? Among experienced specialists, there is no common opinion whether or not to stop taking medications on the eve of the intervention. For example, some experts believe that patients should continue taking antihypertensive drugs in the usual regime until an hour of surgical treatment. And basically, special problems during the anesthesia allowance in connection with such tactics of patient management does not arise.
But today more specialists cover a different approach, which, in their opinion, provides the best hemodynamic stability of the patient during anesthesia:
- ACE inhibitors or angiotensin II antagonists do not need to be canceled if patients receive this medication because of heart failure or left ventricular dysfunction;
- ACE inhibitors or angiotensin II antagonists, prescribed for the cause of AH, should be temporarily discontinued exactly one day before the operation commences;
- Diuretics are not prescribed on the day of surgery Patients should continue receiving beta-blockers in the usual mode.
Perioperative period in patients with arterial hypertension
The main task is to maintain the optimal level of blood pressure during the operation. If there are no special indications, then the physicians are guided by the “working” level of pressure of the sick patient ± 20%. In patients older than 80 years, SBP should preferably not be reduced to less than 150 mm Hg. Art.
Arterial pressure during anesthesia in patients with hypertension may vary significantly. It is capable not only to increase sharply, but also to decrease sharply. For prevention there are such tricks:
If it is planned to carry out controlled ventilation, then 2-3 minutes before intubation it is recommended to inject an increased dose of analgesic (fentanyl is effective at a dose of 3-5 μg / kg) and induction with a drug that does not increase blood pressure (midazolam, propofol, thiopental sodium, diazepam etc). Increasing blood pressure during intubation is a separate anesthetic problem.
When carrying out intravenous anesthesia, as an anesthetic should choose thiopental sodium, propofol, because these are drugs that do not increase blood pressure in humans. It is not necessary to reduce the medicamentous pressure before conducting epidural and spinal anesthesia. Enough to strengthen sedation (midazolam, propofol, diazepam).
When blocking peripheral nerves in an anesthetic, it is recommended to add clonidine (as an adjuvant), which improves the quality of anesthesia and simultaneously – somewhat reduces the patient’s pressure. But, in the overwhelming majority of cases, it is enough to add ataraktika to premedication (a good effect is given in this regard by diazepam and midazolam).
Intraoperative hypotension in patients with arterial hypertension
A sharp decrease in blood pressure in a patient can threaten with various complications that are associated with insufficient blood supply to various organs – myocardial ischemia, stroke, kidney failure, and so on.
Doctors should remember that against the background of antihypertensive therapy, traditionally used to correct hypotension, vasopressors – ephedrine and phenylephrine – may not have the desired effect. In this case, for the treatment of hypotension, norepinephrine (Noradrenaline), epinephrine (adrenaline) or vasopressin is used.
Intraoperative arterial hypertension
It is considered to be a perioperative arterial hypertension in a person when the systolic blood pressure during the operation, and in the chamber of post-nasal awakening, corresponds to one of the following conditions:
- is higher than 200 mm Hg. st;
- exceeds the preoperative level by 50 mm Hg. st;
- requires intravenous administration of antihypertensive drugs.
The most common cause of perioperative hypertension is the activation of the sympathetic nervous system, combined with insufficient depth of blockade of nociceptive stimulation during anesthesia and surgery. Therefore, the traditional method of stopping intraoperative hypertension is called a deepening of anesthesia with the help of narcotic analgesics, inhalation anesthetics and benzodiazepines.
It is recommended for this purpose to take propofol (a bolus of 25-50 mg until the effect is obtained, then, if necessary, you can switch to continuous administration). The drug acts quickly, has a short half-life, is well combined with virtually all drugs that are used for anesthesia.
In many cases, you can appoint a magnesium sulfate patient with a dose of 2-5 g per injection, inject it not immediately, but for 10-15 minutes. This drug not only gently reduces blood pressure, but significantly reduces the need for analgesics during surgery, and in the early postoperative period, improves the quality of anesthesia. In cases that are resistant to this therapy, and also when the pressure needs to be reduced in a short time, doctors use antihypertensive drugs with a short half-life.
Doctors need to take into account that if the patient has been taking beta-adrenoblockers or alpha-adrenergic agonists for a long time, for example clonidine (clonidine), then taking these medicines should be continued after the operation, otherwise, withdrawal can occur with a sharp increase in blood pressure.
First and foremost, treating doctors pay attention to the maintenance of adequate analgesia. As early as possible, it is necessary to resume the intake of those antihypertensive drugs that were effective in this person before the operation. In choosing a drug, specialists sometimes use a special table. But the routine appointment of calcium antagonists medics is not advised, since it is associated with an increased risk of postoperative vascular complications.
Choosing antihypertensive therapy
Low doses of antihypertensive drugs should be used at the initial stage of treatment, starting with the minimum dosage of the drug (the goal is to reduce adverse side effects). If there is a good response to a low dose of this drug, but blood pressure control is still not enough, it is recommended to increase the dosage of this drug, provided it is well tolerated.
Effective combinations of small doses of antihypertensive agents should be used to minimize blood pressure with minimal side effects. This means that when one medication is ineffective, a small dose of the second drug is preferred, rather than an increase in the dosage of the primary drug.
It is necessary to carry out a complete replacement of one class of drugs, to another class of drugs: with a low effect or poor tolerance without increasing the dosage or adding another drug.
Such priority combinations of antihypertensive drugs are recommended:
- Angiotensin II receptor antagonists + diuretic;
- Angiotensin II receptor antagonists + calcium antagonist;
- Angiotensin converting enzyme inhibitors + diuretic;
- Angiotensin converting enzyme inhibitors + calcium antagonist;
- Calcium antagonist + diuretic.
Emergency conditions in hypertension
All situations in which this rapid decrease in blood pressure is required are divided into 2 large groups:
- The first – a group of diseases and conditions, which require an emergency (during 1-2 hours), lowering blood pressure.
In the same group, the complicated hypertensive crisis is reckoned as a sudden (several hours) and a significant increase in blood pressure relative to the level usual for a person. Increased blood pressure leads to the appearance or worsening of symptoms on the part of the target organs:
- myocardial infarction;
- unstable angina;
- about delaminating aortic aneurysm;
- system of left ventricular failure;
- hemorrhagic stroke;
- with trauma or injury of another genesis of the central nervous system;
- edema of the nipple of the optic nerve;
- at patients during operation and in the postoperative period at threat of a bleeding and in some other cases.
For an emergency reduction in blood pressure, parenteral drugs such as:
- nitroglycerin (it is preferred for myocardial ischemia in the patient);
- nitroprusside sodium (suitable for most cases of resistant hypertension);
- magnesium sulfate (preferred for eclampsia);
- esmolol (it is chosen mainly in the defeat of the central nervous system);
- enalapril (preference is given to him in the presence of heart failure in the patient);
- furosemide (preferred for hypervolemia, acute LV deficiency);
- fentolamine (with suspicion of pheochromocytoma).
Recommendations. To avoid ischemia of the central nervous system, kidneys and myocardium, you do not need to lower your blood pressure too quickly. The systolic pressure should be reduced by 25% of the baseline in the first two hours, and to 160/100 mm Hg. Art. – over the next 2-6 hours. In the first 2 hours after the onset of antihypertensive treatment, you need to monitor BP every 15-30 minutes. Dosage of the drug doctors are selected individually. Preference is given to drugs (in the absence of contraindications in each case) with a short half-life.
- The second group, where specialists refer all other cases of BP increase, when it should be normalized within a few hours.
In itself, a sharp increase in blood pressure, without manifestations of symptoms from other organs, requires mandatory, but not so urgent intervention. It can be stopped by oral administration of drugs with a relatively fast action (calcium antagonists (nifedipine), beta adrenoblockers, short-acting ACE inhibitors, clonidine, prazosin, loop diuretics).
It should be noted that the parenteral route of taking antihypertensive drugs should be the exception rather than the rule. That is, in most cases it is not used.
Oral preparations for urgent reduction of arterial pressure
Examples of appointments in such cases:
- moxonidine (Physiotensis) 0.4 mg should be given to the patient for oral administration. Effective is with increasing blood pressure in patients with high sympathetic activity;
- captopril 25-50 mg dubt to the patient inside. Indications: moderate increase in blood pressure in patients without high sympathetic activity;
- nifedipine 10-20 mg sublingually (give the patient chew), in the absence of the effect, repeat the procedure in half an hour. It is shown with a moderate increase in pressure in patients without high sympathetic activity;
- propranolol 40 mg is taken sublingually (orally, with a glass of warm water). It is used in the combination of arterial hypertension with tachycardia.