Home Blood Pressure Monitoring

Dr. Page is an associate professor of clinical pharmacy and physical medicineand a clinical specialist, Division of Cardiology, University of ColoradoHealth Sciences Center, Schools of Pharmacy and Medicine.

• Preeclampsia, Blood Pressure, andMaternal Outcomes: The Important Roleof Home Blood Pressure Monitoring
• Home Is Where the Heart Is:New AHA Guidelines RecommendHome Blood Pressure Monitoring

Preeclampsia, Blood Pressure, andMaternal Outcomes: The Important Roleof Home Blood Pressure Monitoring

Preeclampsia is a leading cause ofmaternal morbidity and pretermdelivery worldwide. It is typicallydefined on the basis of new-onset hypertension(≥140/≥90 mm Hg) and proteinuria(≥0.3 g/24 hours) after 20 weeks of gestationin a previously normotensive woman.Worldwide the incidence of preeclampsiaranges between 3% and 14% of all pregnancieswith about 5% to 8% occurring inthe United States.¹

Stages of Preeclampsia

The pathogenesis of preeclampsia isextremely complex and may be due tointeractions between genetic, immunologic,and environmental factors. Nonetheless,many clinicians have suggested that thedisease may be 2 staged in nature. Thefirst stage is asymptomatic, characterizedby abnormal placental development duringthe first trimester resulting in placentalinsufficiency and the release of excessiveamounts of placental materials into thematernal circulation. This stage then leadsto a second, symptomatic stage, whereinthe pregnant woman develops characteristichypertension, renal impairment, andproteinuria and is at risk for the HELLPsyndrome (hemolysis, elevated liver functionenzymes, and low platelets), eclampsia,and other end-organ damage.²

History of Preeclampsia

Recently, data have suggested that ahistory of preeclampsia may be linked witha significantly increased risk for remotecardiovascular and cerebrovascular disease,such as hypertension, myocardialinfarction, ischemic heart disease, andcerebrovascular accidents.^1,3 In a metaanalysisof 25 studies, Bellamy et al foundthat women with a history of preeclampsiahad an almost 4-fold increased risk ofhypertension (odds ratio [OR] of 3.70), a2-fold increased risk of ischemic heartdisease (OR 2.16), and an almost 2-foldincreased risk of stroke (OR 1.81) andvenous thromboembolism (OR 1.79).³

Based on these findings, it is crucialthat routine home blood pressure monitoring(HBPM) to obtain accurate measureof blood pressure (BP) be conducted aspart of a comprehensive prenatal careplan so as to detect preeclampsia. Earlydetection impacts both present and futurematernal outcomes. The earliest manifestationof preeclampsia is typically a failureto decrease BP or a premature increase ofBP during the second trimester. Cnossenet al, however, found that during the firstor second trimester, the mean arterialpressure is a better predictor for preeclampsia,compared with systolic BP, diastolicBP, or an increase in BP.⁴ HBPM isrecommended because conventional BPreadings conducted in a physician?s officeare prone to inaccuracy due not only toobserver but device error.

Multiple Blood PressureReadings Necessary

In the case of pregnant women, multipleBP readings are warranted, so as topaint an accurate picture of possible suddenBP changes. Furthermore, many BPmeasurement devices underestimate BPin women with preeclampsia. Data wouldsuggest that a device that detects oscillationson inflation rather than deflationfrom a pneumatic cuff, such as the newOmron Advanced Women?s BP monitor,could be more accurate in this population.⁵

The use of an approved HBPM devicecould correct all of these deficiencies.HBPM is not only convenient for the motherbut provides a 24-hour picture of themother?s hemodynamics for the physician.As a health care expert, pharmacistscan recommend the most appropriatedevice and educate expectant motherson how to use the machine. Overall, theincorporation of HBPM into a comprehensiveprenatal-care plan can provide peaceof mind for both mother and clinician.

References

• Harskamp RE, Zeeman GG. Preeclampsia: at risk for remote cardiovascular disease. Am J Med Sci. 2007;334:291-295.
• Hladunewich M, Karumanchi SA, Lafayette R. Pathophysiology of the clinical manifestations of preeclampsia. Clin J Am Soc Nephrol. 2007;2:543-549.
• Bellamy L, Casas JP, Hingorani AD, et al. Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis. BMJ. 2007;335:974.
• Cnossen JS, Vollebregt KC, de Vrieze N, et al. Accuracy of mean arterial pressure and blood pressure measurements in predicting pre-eclampsia: systematic review and meta-analysis. BMJ. 2008;336:1117-1120.
• Golara M, Benedict A, Jones C, et al. Inflationary oscillometry provides accurate measurement of blood pressure in pre-eclampsia. BJOG. 2002;109:1143-1147.

Home Is Where the Heart Is:New AHA Guidelines RecommendHome Blood Pressure Monitoring

On May 22, 2008, the AmericanHeart Association (AHA), theAmerican Society of Hypertension,and the Preventive CardiovascularNursing Association issued a new jointscientific statement calling for patientswith or at risk of hypertension to routinelymonitor their blood pressure (BP)at home. Earlier AHA guidelines haveincluded home monitors; however, thisis the first statement to have specificrecommendations on their use.

A call to action, if followed by patientsand clinicians, could dramatically improvethe cost-effective quality and cost ofdelivering care to the >100 million individualswith or at risk of hypertension,through improvement in control of BP andenhanced adherence to pharmacotherapy.The committee writing the statementnoted that while traditional methods ofmeasuring BP with the auscultatory techniquein a clinic or office setting will likelyremain the cornerstone for the diagnosisand management of hypertension, theauscultatory method is not 100% foolproofand does have its drawbacks.

Benefits of Home Blood Pressure Monitoring

Home blood pressure monitoring(HBPM) offers many advantages. HBPMprovides an average BP measurementover time, thus eliminating inadequateor misleading measurements that maybe generated with in-office BP measurements.As with home blood glucose monitoring,HBPM has the potential to beincorporated into routine clinical careby patients with or at risk of hypertension.The committee recommended thatHBPM should especially be consideredin patients with newly diagnosed or suspectedhypertension, in whom it mighthelp to distinguish between white-coatand sustained hypertension.

Patient populations where HBPM alsowould be useful are seniors, children, andpregnant women, as well as patients withdiabetes and/or kidney disease, as thesetypes of populations are at increased riskfor large variability in BP and white-coathypertension. Furthermore, HBPM couldbe used to detect masked hypertensionand is recommended for evaluating theresponse to antihypertensive therapy.Even with these advantages, however,the committee cautions that patientsshould only consider purchasing a monitorthat has been validated for accuracyand reliability according to standard internationaltest protocols. Patients shouldonly buy devices that have been validatedaccording to the European Society ofHypertension, the British HypertensionSociety, or the Association for theAdvancement of Medical Instrumentation.

An up-to-date list of validated monitors,and those that have failed validation,is available on the dabl EducationalWeb site (www.dableducational.org) or the British HypertensionSociety Web site (www.bhsoc.org). Furthermore, the committeesuggests that preference be givento devices that have automatic inflationof cuffs, oscillometric detection, andmemory. Unfortunately, not all patientsare candidates for HBPM, such as thosewith atrial fibrillation or other arrhythmiawhere the oscillometric method may notbe as effective.

Pharmacists' Role

Due to their training, knowledge base,and position in the patient care environment,the pharmacist has been shown toplay a crucial role in the management ofpatients with hypertension. In the case ofHBPM, pharmacists can identify appropriatepatients who warrant HBPM and alsoassist patients in identifying a monitorthat is suitable to their needs and provideinstruction on how to properly use thedevice.

This communication on the importance of home blood pressure monitoring is supported by OmronHealthcare Inc. It is intended to help pharmacists and their staff understand the importance ofhome blood pressure monitoring for women, especially if they are pregnant.