- CONDITION CENTERS
Dr. Page is an associate professor of clinical pharmacy and physical medicine and a clinical specialist, Division of Cardiology, University of Colorado Health Sciences Center, Schools of Pharmacy and Medicine.
Preeclampsia is a leading cause of maternal morbidity and preterm delivery worldwide. It is typically defined on the basis of new-onset hypertension (≥140/≥90 mm Hg) and proteinuria (≥0.3 g/24 hours) after 20 weeks of gestation in a previously normotensive woman. Worldwide the incidence of preeclampsia ranges between 3% and 14% of all pregnancies with about 5% to 8% occurring in the United States.1
The pathogenesis of preeclampsia is extremely complex and may be due to interactions between genetic, immunologic, and environmental factors. Nonetheless, many clinicians have suggested that the disease may be 2 staged in nature. The first stage is asymptomatic, characterized by abnormal placental development during the first trimester resulting in placental insufficiency and the release of excessive amounts of placental materials into the maternal circulation. This stage then leads to a second, symptomatic stage, wherein the pregnant woman develops characteristic hypertension, renal impairment, and proteinuria and is at risk for the HELLP syndrome (hemolysis, elevated liver function enzymes, and low platelets), eclampsia, and other end-organ damage.2
Recently, data have suggested that a history of preeclampsia may be linked with a significantly increased risk for remote cardiovascular and cerebrovascular disease, such as hypertension, myocardial infarction, ischemic heart disease, and cerebrovascular accidents.1,3 In a metaanalysis of 25 studies, Bellamy et al found that women with a history of preeclampsia had an almost 4-fold increased risk of hypertension (odds ratio [OR] of 3.70), a 2-fold increased risk of ischemic heart disease (OR 2.16), and an almost 2-fold increased risk of stroke (OR 1.81) and venous thromboembolism (OR 1.79).3
Based on these findings, it is crucial that routine home blood pressure monitoring (HBPM) to obtain accurate measure of blood pressure (BP) be conducted as part of a comprehensive prenatal care plan so as to detect preeclampsia. Early detection impacts both present and future maternal outcomes. The earliest manifestation of preeclampsia is typically a failure to decrease BP or a premature increase of BP during the second trimester. Cnossen et al, however, found that during the first or second trimester, the mean arterial pressure is a better predictor for preeclampsia, compared with systolic BP, diastolic BP, or an increase in BP.4 HBPM is recommended because conventional BP readings conducted in a physician?s office are prone to inaccuracy due not only to observer but device error.
In the case of pregnant women, multiple BP readings are warranted, so as to paint an accurate picture of possible sudden BP changes. Furthermore, many BP measurement devices underestimate BP in women with preeclampsia. Data would suggest that a device that detects oscillations on inflation rather than deflation from a pneumatic cuff, such as the new Omron Advanced Women?s BP monitor, could be more accurate in this population.5
The use of an approved HBPM device could correct all of these deficiencies. HBPM is not only convenient for the mother but provides a 24-hour picture of the mother?s hemodynamics for the physician. As a health care expert, pharmacists can recommend the most appropriate device and educate expectant mothers on how to use the machine. Overall, the incorporation of HBPM into a comprehensive prenatal-care plan can provide peace of mind for both mother and clinician.
On May 22, 2008, the American Heart Association (AHA), the American Society of Hypertension, and the Preventive Cardiovascular Nursing Association issued a new joint scientific statement calling for patients with or at risk of hypertension to routinely monitor their blood pressure (BP) at home. Earlier AHA guidelines have included home monitors; however, this is the first statement to have specific recommendations on their use.
A call to action, if followed by patients and clinicians, could dramatically improve the cost-effective quality and cost of delivering care to the >100 million individuals with or at risk of hypertension, through improvement in control of BP and enhanced adherence to pharmacotherapy. The committee writing the statement noted that while traditional methods of measuring BP with the auscultatory technique in a clinic or office setting will likely remain the cornerstone for the diagnosis and management of hypertension, the auscultatory method is not 100% foolproof and does have its drawbacks.
Home blood pressure monitoring (HBPM) offers many advantages. HBPM provides an average BP measurement over time, thus eliminating inadequate or misleading measurements that may be generated with in-office BP measurements. As with home blood glucose monitoring, HBPM has the potential to be incorporated into routine clinical care by patients with or at risk of hypertension. The committee recommended that HBPM should especially be considered in patients with newly diagnosed or suspected hypertension, in whom it might help to distinguish between white-coat and sustained hypertension.
Patient populations where HBPM also would be useful are seniors, children, and pregnant women, as well as patients with diabetes and/or kidney disease, as these types of populations are at increased risk for large variability in BP and white-coat hypertension. Furthermore, HBPM could be used to detect masked hypertension and is recommended for evaluating the response to antihypertensive therapy. Even with these advantages, however, the committee cautions that patients should only consider purchasing a monitor that has been validated for accuracy and reliability according to standard international test protocols. Patients should only buy devices that have been validated according to the European Society of Hypertension, the British Hypertension Society, or the Association for the Advancement of Medical Instrumentation.
An up-to-date list of validated monitors, and those that have failed validation, is available on the dabl Educational Web site (www.dableducational.org) or the British Hypertension Society Web site (www.bhsoc.org). Furthermore, the committee suggests that preference be given to devices that have automatic inflation of cuffs, oscillometric detection, and memory. Unfortunately, not all patients are candidates for HBPM, such as those with atrial fibrillation or other arrhythmia where the oscillometric method may not be as effective.
Due to their training, knowledge base, and position in the patient care environment, the pharmacist has been shown to play a crucial role in the management of patients with hypertension. In the case of HBPM, pharmacists can identify appropriate patients who warrant HBPM and also assist patients in identifying a monitor that is suitable to their needs and provide instruction on how to properly use the device.
This communication on the importance of home blood pressure monitoring is supported by Omron Healthcare Inc. It is intended to help pharmacists and their staff understand the importance of home blood pressure monitoring for women, especially if they are pregnant.