 |
Management of CHP
|
|
|
|
Patients with pre existing hypertension at pregnancy refer to group of high risk of maternal and perinatal morbidity and mortality. The aims of following up of this group of patient is prevention of superimposed preeclampsia (PE), prevention of maternal and fetal complications (premature separation of placenta, fetal distress, intrauterine growth restriction, hemorrhages in labor and puerperium, etc. ), prevention of maternal mortality. Medications should be reviewed immediately once pregnancy is diagnosed, in patients with a recognized diagnosis of chronic hypertension. To avoid the death of a mother with chronic hypertension due to pregnancy and childbirth, it is necessary determine high-risk patients before the 12th week of pregnancy. Pregnancy and childbirth may be even contraindicated for some patients with severe chronic hypertension. In such cases, medical termination of pregnancy should be proposed for the woman.
Contraindications for prolonging of pregnancy in chronic hypertension, which was evaluated before the 12th wks:
- Severe arterial hypertension (BP≥ 180/110 mm Hg)
- Diastolic BP ≥ 130 mm. Hg
- Affection of internal organs (because of hypertension): heart, liver, kidneys, brain dysfunction
- Signs of neuropathy
- Neurorethinopathy
For those, who have no contraindications for carrying of a pregnancy, the following laboratory studies should be obtained in the 1st trimester: CBC count, electrolytes, blood urea nitrogen (BUN) test, creatinine, liver enzymes, and urine dip for protein and a 24-hour urine collection for creatinine clearance and protein excretion. The results should be served as baseline values, to be referred to later in the pregnancy if a concern regarding superimposed preeclampsia arises.
Medications should be reviewed: Angiotensin converting enzyme (ACE)inhibitors and Angiotensin receptor blockers (ARBs) are contraindicated in pregnancy because of teratogenic effect. Antihypertensive drugs, which may be used in the first trimester of pregnancy, are: methyldopa, labetalol, and nifedipine. The basic treatment is: methyldopa 250-500 mg tds /qid. Methyldopa reduces central sympathetic outflow by stimulating brainstem α 2 receptors. It is a medicine of the 1st choice of oral anti-hypertensive for long-term treatment. The onset of action is usually during 7-12 hours; fall in ABP maximal 4-8 hours after oral ingestion; the duration of action: 12-24 hours. Maximal dosage is 1gr tds. Side effects: transient oliguria, dry mouth, lethargy, drowsiness, impaired liver function.
Day care assessment should be considered if the dBP is between 90-100 mm Hg and there is no proteinuria. If the dBP is between 90-100 mm Hg, the patient can be managed as outpatient and following are prescribed in this case:
· monitoring of ABP 3 times a day and recording a chart,
· weekly visiting to obstetrician,
· a CBC: every 2 weeks,
· urinalysis - before every visit to the obstetrician.
Prevention of superimposed PE is mandatory:
|
|
|
· Acetylsalicylic acid 60-100 mg/day starting from the 20th wk gestation
· The administration of Ca++ (1. 5g -2g/ day) from the 16th -18th week of gestational amenorrhea.
The follow-up of expectant mother with CHP should be out-patient, with accurate and constant control of ABP and antihypertensive treatment, maternal and fetal conditions up to the term of labor, in case of non-complicated course of pregnancy.
Criteria for inpatient management:
· dBP > 100 mm Hg with or without antihypertensive therapy
· Significant proteinuria (> 0. 3 g/day)
· Evidence of maternal and fetal compromise
· Symptomatic patient
· Patient with biochemical complications
Antihypertensive treatment in the hospital.
The 1st line therapy:
· Labetolol (Trandate ) 100 mg 8 hourly. Maximal dose 400 mg 8 hourly; or
· Alpha Methyldopa (Aldomet ) 250 mg every 8 hourly. Maximal dose 1 g 8 hourly.
· If dBP remains ≥ 100 mm Hg after 24-48 hrs of treatment the initial dose should be doubled.
The second line of antihypertensive agent is nifedipine: 10 mg 8 hourly with the maximal dose 40 mg 8 hourly should be prescribed.
Hydralazine should be started if dBP ≥ 110 mm Hg, or MAP > 125 mm Hg. The mean arterial pressure (MAP) is a term used in medicine to describe an average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle. Mean arterial pressure can be determined from: MAP= (CO х SVR) + CVP
where:
• CO is cardiac output
• SVR is systemic vascular resistance
• CVP is central venous pressure and usually small enough to be neglected in this formula.
The mean arterial pressure (MAP) is defined as the average arterial pressure during a single cardiac cycle. It is determined by the cardiac output (CO), systemic vascular resistance (SVR), and central venous pressure (CVP) according to the following relationship, which is based upon the relationship between flow, pressure and resistance: MAP = (CO × SVR) + CVP.
In practice, more frequently, MAP can be approximated by the following equation: MAP 
DP+1/3(sP-dP), usually used in case of normal resting heart rates.
MAP is considered the perfusion pressure seen by organs in the body. The normal range of MAP is 70-105 mmHg. It is believed that a MAP that is greater than 70 mmHg is enough to sustain the organs of the average person. If the MAP falls significantly below this number for an appreciable time, the end organ will not get enough blood flow, and will become ischemic. A mean arterial pressure (MAP) that is above 105 mmHg indicates the heart is having to work much harder than it should and can cause stress on the heart. When the pressure goes too high and stress on the heart increases, fatty deposits build up on the inside of the arteries. These are called “atheroma” and can lead to advanced heart disease, blood clots, heart attacks or stroke. If the blood pressure remains high and the MAP remains elevated, the heart muscle will enlarge and grow thicker. It will also weaken the muscle. If the MAP is severely elevated, then the life expectancy is only a few years without treatment. If the MAP goes up critically in a short amount of time, this is a medical emergency because the increased blood flow to the organs can cause organ failure.
|
|
|
