Gestational hypertension is more common clinically and it is defined as an increase in absolute blood pressure (≥140/90 mm Hg or higher) during pregnancy and also includes increased blood pressure levels (≥25 mm Hg increase in systolic blood pressure and/or ≥15 mm Hg increase in diastolic blood pressure) in the first trimester of pregnancy compared to the original blood pressure.
Hypertension in pregnancy can be divided into 4 different types, namely.
(1) Gestational hypertensive syndrome: hypertension appears at 20 weeks of gestation and returns to normal 6 weeks after delivery.
(2) Chronic hypertension that can be caused by any cause: it can persist during pregnancy, such as primary hypertension; glomerulonephritis, pheochromocytoma, and primary aldosteronism can also cause hypertension.
(3) Combination of preeclampsia and eclampsia on top of chronic hypertension.
(4) Transient hypertension.
Hypertension in pregnancy is very dangerous and can lead to convulsions, coma, heart failure and other multi-organ damage, and in serious cases, even threaten the life of the mother and child, and may also cause sequelae.
I. Treatment of hypertension in pregnancy
The treatment of hypertension during pregnancy is different from that of general hypertension, and comprehensive measures should be taken according to different etiologies, such as diet, activities and drugs, in order to control blood pressure.
1, non-pharmacological treatment: ① adequate bed rest and eliminate tension. ②Low salt diet. ③Calcium supplementation: Calcium supplementation of 1.5-2.0 grams per day can reduce systolic and diastolic blood pressure by 5.4 mm Hg and 3.4 mm Hg, respectively. Calcium supplementation is very beneficial in people with low calcium intake. However, calcium supplementation does not reduce the incidence of pre-eclampsia.
2, drug treatment: Although antihypertensive drugs can make pregnant women’s blood pressure drop, but because antihypertensive drugs have adverse effects on the fetus, therefore, women with hypertension during pregnancy should use antihypertensive drugs with caution. If the blood pressure is mildly elevated in the first trimester and there are no complications, you should stop taking antihypertensive drugs in early pregnancy, because there is often physiological hypotension during pregnancy, so there is no need for medication. However, if the blood pressure value is greater than or equal to 140/90 mmHg, medication should be applied, and drugs that are not teratogenic to the fetus should be chosen.
The following drugs are currently considered suitable for hypertension in pregnancy.
(1) Methyldopa is a central a2-receptor agonist, the dosage is 0.5~2g/day, the strongest effect is 4~6 hours after oral administration, metabolized by kidney, it does not cause decrease in cardiac output and increase in reflex sympathetic activity, does not affect placental blood supply, and is safe for both mother and child. It not only reduces maternal mortality and the incidence of spontaneous abortion, but also has the effect of improving the perinatal survival rate of the fetus. The main adverse effects are sedation and depression.
(2) Colistin is another central a2 agonist, the dosage is 0.1~0.5 mg/day, taken orally. It has no adverse effect on neurodevelopment and intelligence of young children, but it has withdrawal reaction, and the blood pressure will increase rebound when withdrawn suddenly. The main adverse reactions are dry mouth, drowsiness, and increased reactive heart rate.
(3) Nifedipine is a dihydropyridine calcium channel blocker, long-term use can increase the blood supply to the placenta and brain, can improve renal perfusion, and can increase the ratio of prostaglandin/thromboxane, and is not harmful to mother and child. Nifedipine has the effect of suppressing contractions, but studies have shown that it does not affect labor or increase postpartum bleeding. However, it should be noted that the combination of nifedipine and magnesium sulfate can cause low blood pressure. And there are no other dihydropyridine drugs for the treatment of gestational hypertension research reports.
(4) Labetalol (lorazepam) is an alpha, beta-blocker, generally administered intravenously 50 mg/dose, repeatable at 5-minute intervals: or 0.5-2 mg/minute intravenous drip for hypertensive emergencies. 100 mg/dose orally, 2 to 3 times/day, as a second-line drug.
(5) Prazosin (pulse nimbin) is an a-receptor antagonist, safe for both mother and child. Dosage 0.5-1 mg/dose, 2-3 times/day orally. Total dose is 6-10 mg/day. The first time to take easy to produce postural hypotension, in 0.5 ~ 2 hours after taking the drug, known as the “first dose phenomenon”, therefore, the first dose should be given at bedtime.
(6) magnesium sulfate is the most effective drug for the prevention and treatment of eclampsia, has the protection of endothelial cells, increase the release of prostaglandin and prostacyclin synthesis, inhibit the level of endothelin and prevent calcium from entering the role of intracellular, thus lifting the vasospasm. Usage and dosage: first give 5-6 grams of magnesium sulfate dissolved in 5% glucose solution 100 ml, 20-60 minutes intravenous drip finished, and then maintain intravenous drip at the rate of 1-1.5 grams / hour, the total amount does not exceed 30 grams / 24 hours. The blood concentration of magnesium sulfate after treatment is 2~3 mmol/l. If the blood magnesium is more than 3.5 mmol/liter, the double knee reflex disappears; the blood magnesium is more than 7.5 mmol/liter, the heartbeat and respiratory arrest can occur. It is best to monitor the blood magnesium during the medication, such as no conditions to monitor, can closely observe the following indicators to indicate the excess of magnesium sulfate: a. knee reflex disappears; b. respiration less than 16 times / min; c. urine volume less than 25 ml / h.
(7) nitroglycerin is a direct peripheral vasodilator. When administered in high doses, it can significantly dilate small arteries. The usual dose is 25 mg added to 500 ml of fluid intravenously at a rate of 20-60 mcg/min (8-10 drops/min).
(8) Sodium nitroprusside is a direct peripheral vasodilator, especially suitable for hypertension in pregnancy when preeclampsia and eclampsia occur, hypertension combined with left heart failure and hypertensive encephalopathy. 50 mg is commonly added to 500 ml of 5% glucose solution and administered intravenously at a rate of 20 micrograms/minute (4-6 drops/minute), with the dose adjusted according to blood pressure. It should be noted that its metabolites (cyanide) are not suitable for use during pregnancy due to their toxic effects on the fetus. It is mostly used during labor or postpartum when blood pressure is too high and the application of other antihypertensive drugs is not effective.
When using antihypertensive drugs in patients with hypertension during pregnancy, blood pressure changes must be closely observed and should be monitored once or twice a day to avoid excessive blood pressure reduction and large fluctuations that could affect the fetal blood supply. Blood pressure should be controlled at 130 to 140/80 to 85 mm Hg as appropriate.
For eclampsia, hypertensive crisis, hypertensive encephalopathy pregnant women and other emergencies, because at the same time endanger the lives of both mother and child, it is necessary to immediately take injectable drugs to reduce blood pressure to a safe range (160-170/100-110mmHg), and later gradually transition to oral antihypertensive drug therapy. May prefer 10% magnesium sulfate 10ml plus 5% glucose solution 20ml intravenous injection, or 25% magnesium sulfate 10ml intramuscular injection, such as the effect is not satisfactory can be promptly replaced with sodium nitroprusside. In addition, nitroglycerin, sodium nitroprusside, uradil can also be used. Note that the treatment of eclampsia is not only to lower blood pressure, should be timely control of convulsions (such as diazepam 5-20mg intravenous), lower cranial pressure (such as 20% mannitol 125-250ml rapid intravenous drip) and other symptomatic treatment (such as oxygenation, sedation, supportive therapy).
However, special attention should be paid to: angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists can increase maternal mortality and fetal teratogenicity, and their use is contraindicated; diuretics can cause a decrease in blood volume and therefore should not be used; intravenous hydrazidiazine has more side effects and is no longer used; in addition, calcium channel blockers and MgSO4 should not be used in combination.
The drugs that should be used with caution and should not be used in patients with hypertension during pregnancy include.
(1) Diuretics Diuretics can aggravate the condition of blood volume deficiency in pregnant women and can cause neonatal jaundice and electrolyte disorders in pregnant women, so their use is generally not recommended. They should be used with caution unless combined with heart failure or significant water and sodium retention. However, if a pregnant woman has started taking diuretics before pregnancy and there are no adverse reactions such as pre-eclampsia, she can continue to take them at small doses (12.5-25 mg/day) for maintenance. In case of pre-eclampsia, it is not recommended to continue to take it.
(2) β-blockers because β-blockers can pass through the placenta and reduce the uteroplacental blood supply, which can cause intrauterine fetal growth retardation, neonatal respiratory disorders and hypoglycemia, indolol and atenolol have the above-mentioned effects, unless other drugs can not effectively lower blood pressure, so they should not be used in early and middle pregnancy.
(3) Angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists should not be used because the decrease in systemic blood pressure caused by them will reduce blood flow to the uterus, which may cause fetal growth retardation, low amniotic fluid, congenital malformations and neonatal renal failure.
Prevention of hypertension in pregnancy
Advocate and promote pre-conception medical examination, especially those women who have a family history of hypertension, diabetes and other cardiovascular diseases, must check the blood pressure before deciding to conceive.
Women with chronic hypertension prior to pregnancy should closely monitor their blood pressure levels; those with blood pressure levels below 130/80 mm Hg can be considered for conception; those with blood pressure levels greater than 140/90 mm Hg should avoid conception.
Blood pressure levels need to be closely monitored throughout pregnancy, and attention should be paid to any edema in the lower extremities and changes in urine output, with prompt access to the hospital if abnormalities are detected.
Once a tendency of pre-eclampsia or eclampsia is detected, emergency treatment should be carried out at the hospital for the safety of mother and baby.