Combined hypertension in pregnancy can increase fetal growth restriction, placental abruption, DIC, acute heart failure and other complications, and proper blood pressure control can reduce maternal and infant mortality.
I. Selection of antihypertensive drugs
1. Principles of drug selection
In the effective control of blood pressure, the safety of drugs for mother and child should be fully considered. ACEI, ARB and renin inhibitors are prohibited in patients with hypertension during pregnancy because of their teratogenic side effects.
2.Guideline recommendations
(1)Chinese hypertension prevention and treatment guidelines 2010 edition
Pharmacological treatment should be started when blood pressure is ≥150/100 mmHg, and the goal of treatment is to control blood pressure at 130~140/80~90 mmHg. optional drugs include
①Methyldopa: 200~500mg, 2~4 times/day;
(ii) Labetalol: 50-200 mg every 12 hours, maximum 600 mg/d;
③Metoprolol: 25~100mg, 1 time every 12 hours; ④Hydrochlorothiazide: 6.25~25 mg/d;
⑤Nifedipine: 5~20 mg every 8 hours, or extended release formulation, 10~20 mg every 12 hours;
⑥Hydrazidiazine: 10 mg/d, 4 times a day, maximum 400 mg/day.
(2) Japanese hypertension guidelines 2014 edition
The target value of blood pressure lowering is <160/110 mmHg, or the average blood pressure decreases by 15%~20%. Blood pressure lowering is divided into three steps.
(1) First, use one of methyldopa, hydrazinepyridazine, or labetalol;
②If the effect is not satisfactory, the combination of methyldopa and hydrazinepyridazine or labetalol and hydrazinepyridazine can be applied;
(③Add nifedipine to methyldopa combined with hydrazinpyridazine. (See Figure 1)
(3) European hypertension guidelines 2013 edition
Pharmacotherapy is recommended for severe hypertension (SBP > 160 mmHg and/or DBP > 110 mmHg) (Exhibit I); pharmacotherapy is also indicated for hypertension in pregnancy in women with persistently elevated BP ≥ 150/95 mmHg, and in women with combined subclinical target organ damage or symptoms and BP ≥ 140/90 mmHg (Exhibit IIb). Antihypertensive drugs are first considered methyldopa, labetalol, and nifedipine. Labetalol and nifedipine can be considered for emergency intravenous medication.
3. Hypertensive emergencies
Need emergency admission, intravenous application of antihypertensive drugs.
① magnesium sulfate: 5 g diluted to 20 ml, intravenous slow injection (5 minutes), maintenance amount 1 ~ 2 g/h; or 5 g diluted to 20 ml, deep intramuscular injection, every 4 hours. Total dose is 25~30 g/d. Pay attention to toxic reactions.
②Labetalol: 20 mg, intravenous injection, 1~2 mg/min IV.
③Urradil: 10~15 mg, slow intravenous injection; the maximum drug concentration of intravenous infusion is 4 mg/ml, and the recommended initial rate is 2 mg/min, and adjusted according to blood pressure.
④Nitroprusside: intravenous infusion, start 0.5 μg/kg/min. gradually adjust the dose in increments of 0.5 μg/kg per minute according to the therapeutic response, and the extreme amount is 10 μg/kg/min.
II. Precautions
1. In patients with mild hypertension combined with pregnancy, there is no evidence of fetal benefit from drug therapy or prevention of pre-eclampsia. Therefore, such patients can be treated with non-pharmacological therapy and actively monitor blood pressure and regularly review urine routine and other related tests.
2. There is a lack of definite clinical evidence regarding the blood pressure value and the target value of blood pressure lowering for starting antihypertensive drugs. Most guidelines and expert consensus believe that 150/100mmHg can be used as the starting value and target value of antihypertensive treatment. In the absence of risk factors such as proteinuria and other target organ damage, drug therapy can be initiated above 160/110 mmHg.
3. No antihypertensive drug is absolutely safe for patients with hypertension in pregnancy. Except for methyldopa and hydrochlorothiazide, which are classified as Class B in the safety evaluation of the U.S. Food and Drug Administration, most antihypertensive drugs belong to Class C level. Therefore, when selecting medications for patients with hypertension in pregnancy, the pros and cons should be weighed and the patient should be given adequate information before administration.