Accuracy of Automated Blood Pressure Measurement in Children
2017; Lippincott Williams & Wilkins; Volume: 69; Issue: 6 Linguagem: Inglês
10.1161/hypertensionaha.116.08553
ISSN1524-4563
AutoresGeorge S. Stergiou, N. Boubouchairopoulou, Αναστάσιος Κόλλιας,
Tópico(s)Non-Invasive Vital Sign Monitoring
ResumoHomeHypertensionVol. 69, No. 6Accuracy of Automated Blood Pressure Measurement in Children Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBAccuracy of Automated Blood Pressure Measurement in ChildrenEvidence, Issues, and Perspectives George S. Stergiou, Nadia Boubouchairopoulou and Anastasios Kollias George S. StergiouGeorge S. Stergiou From the Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece. , Nadia BoubouchairopoulouNadia Boubouchairopoulou From the Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece. and Anastasios KolliasAnastasios Kollias From the Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece. Originally published24 Apr 2017https://doi.org/10.1161/HYPERTENSIONAHA.116.08553Hypertension. 2017;69:1000–1006Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: January 1, 2017: Previous Version 1 There is a general consensus in the European1 and American2 guidelines for pediatric hypertension that children from 3 years of age and older who are seen in a medical setting should have their blood pressure (BP) measured. This is because hypertension in children and adolescents has become an emerging public health issue, with increasing prevalence mainly driven by the obesity epidemic in this population.1,2 Because hypertension is almost always asymptomatic until there is severe organ damage or it evolves into a malignant phase, the only method for early detection and intervention aiming to prevent its complications is the measurement of BP.The accurate measurement of BP is a prerequisite in the adults and in children for the reliable diagnosis of hypertension and the avoidance of misdiagnosis and over- or undertreatment.1,2 The main methods for noninvasive measurement of BP are the auscultatory method using conventional mercury or aneroid devices and the automated method using electronic, mostly oscillometric, devices.3 This article aims to discuss the evidence and the issues of automated BP measurement in children (age 3–12 years).Auscultatory BP Measurement in ChildrenCurrent guidelines for pediatric hypertension in Europe1 and the United States2 recommend the auscultatory BP measurement method for the diagnosis of hypertension in children. If elevated BP in children is detected by an electronic (oscillometric) BP monitor, it should be confirmed by auscultatory BP measurement.1,2 This is mainly because in children, the available reference values for defining the threshold for hypertension diagnosis have been obtained by the auscultatory method and the fact that auscultatory and automated electronic BP measurements are not necessarily interchangeable.1In children, the auscultatory BP measurement encounters several obstacles, mainly because of anatomic and physiological characteristics of the young individuals. These include small arm dimensions, small and elastic arteries, small waveforms, large differences between peripheral (brachial) and central (aortic) BP, occasional need to use Korotkov sound K4 for defining diastolic BP because Korotkov sounds might be audible when the cuff is fully deflated, and difficulties in defining K4 (sounds of low amplitude and often difficult to hear).1,4,5 In addition, as it is the case also in the adults, the auscultatory BP measurement even when applied in a medical setting is subject to observer error, prejudice and bias, and terminal digit preference.3Automated (Oscillometric) BP Measurement in ChildrenAmbulatory BP MonitoringIn children, the phenomena of white-coat and masked hypertension are particularly common as in the adults.1,6 Therefore, out-of-office BP evaluation with 24-hour ambulatory BP monitoring is recommended by European1 and American6 guidelines for confirming hypertension in children before starting antihypertensive drug treatment. This is in line with the guidelines by major scientific organizations recommending ambulatory BP monitoring for confirming the diagnosis of hypertension in adults before proceeding to any investigation or treatment.7–9Ambulatory BP monitoring is by definition automated, and almost all the monitors available on the market are oscillometric.10 Furthermore, the recommended reference values for defining ambulatory hypertension in children have been derived using an oscillometric device.1,6Home BP MonitoringSurveys in the United States, Canada, and Germany showed that >70% of the pediatric nephrologists use home BP monitoring in children with hypertension or renal disease, and 64% of them consider these measurements as more important than the office measurements.11,12 Home BP monitoring in children has been less well studied than ambulatory monitoring1,13,14 and shown to be useful in the detection of white-coat and masked hypertension.15 As ambulatory BP monitoring cannot be easily performed frequently, home BP monitoring is recommended for regular follow-up of treated hypertension in children, aiming to improve the assessment of BP control.1For home BP monitoring in adults, electronic devices are recommended because they avoid the observer bias and error and require less training than the auscultatory devices.16 In children, because the available evidence on the clinical application of home BP monitoring,1,13 as well as its reference values,1,17 have been obtained using electronic devices, such devices should be preferred in clinical practice.Office BP MeasurementFor professional office or clinic BP measurement in children, the auscultatory method using a standard mercury sphygmomanometer is regarded as the standard.1,2 However, because of environmental issues with mercury toxicity and issues related to service for devices' maintenance and potential mercury spillage in the medical setting, mercury sphygmomanometers are being progressively banned from medical use and are being replaced mainly by professional aneroid or electronic (oscillometric) devices.18 Aneroid devices are widely available and commonly used, but require the auscultatory method and, thus, are subject to the abovementioned observer-related drawbacks.18 Also, they may lose accuracy in long-term use and require regular maintenance and calibration. Electronic oscillometric devices have gained ground over the other standard methods during the last years. However, as mentioned earlier, it is currently recommended that elevated BP in children detected using an electronic BP monitor requires confirmation by auscultatory measurement.1,2 Thus, the auscultatory method remains the gold standard for office BP measurement in children.Independent from the measurement method, in adults,7–9 as well as in children,1,6 it is widely recognized that office BP measurement alone can be insufficient for the reliable diagnosis of hypertension and the decision for long-term drug treatment, mainly because of the white-coat and masked hypertension phenomena.In conclusion, current guidelines for pediatric hypertension recommend the wide use of out-of-office BP monitoring for the initial diagnosis (mainly ambulatory BP monitoring)1,6 and also for the long-term follow-up (mainly home BP monitoring).1 Because out-of-office BP monitoring is based almost exclusively on automated BP measurements and reference values are derived from such measurements,1,6 the wide use of automated BP monitors is often needed in clinical practice for confirming hypertension out of the office.Methodology for the Validation of BP Monitors in ChildrenThe accuracy of the device is fundamental to any method of BP measurement.3 It is acknowledged that the accuracy of electronic BP monitors should be tested in independent validation studies, and relevant protocols have been developed.19–21 The validation of a BP monitor in children faces several challenges, which are because of their special structural and functional characteristics, including small arms but with wide variation requiring several cuff sizes, relatively low BP levels, and difficulties in the accurate assessment of diastolic BP because of the abovementioned issues in defining Korotkov sounds K4 and K5 in children.4,5 Thus, the validation protocols developed for adults are not fully applicable in children, and several adaptations are needed. More importantly, there are data suggesting that an electronic BP monitor that has been successfully validated in adults might be inaccurate in children.19–22 Thus, children are regarded as a special population for BP monitors validation, requiring separate validation studies.19–21The British Hypertension Society (BHS) validation protocol is the oldest one still in use and requires a device to be tested in 30 children aged 5 to 15 years, after a successful study in general population has been completed (Table 1).19 The BHS protocol has specific inclusion criteria for children, in regard to their age, sex, and entry BP distribution. The mean BP difference between test device and reference measurements and its standard deviation need to be reported, yet there are no fixed pass criteria as for general population studies (Table 1).Table 1. Key Features of Current Protocols for the Validation of Blood Pressure Monitors in ChildrenRequirementsBHS19ESH-IP21ANSI/AAMI/ISO20Number of children30, if the device has been successfully validated in general population33 for narrow age range (otherwise to be adjusted)Device for children/adults or with pediatric mode: 35; device only for children: 85Age range5–15 y (younger subjects in separate study)NS3–12 y (additional requirements for younger subjects)Age distributionEven distributionNSNSSexDistribution by chance≥10 (30%) male, ≥10 (30%) female≥30% male, ≥30% femaleBP range5 with SBP >mean+1 SD for population; 5 with DBP 70th and 5 12 years) and analyzed altogether, which might miss an inferior level of accuracy in children or in older subjects. Both the 85-child and the 85-mixed population studies should meet the 2 ANSI/AAMI/ISO criteria for BP differences of individual readings and of individual subjects (Table 1).20The European Society of Hypertension International Protocol has been developed specifically for adults (Table 1).21 Thus, no specific recommendations for special groups such as children are provided. It is stated, however, that a 33-subject study is appropriate only if a narrow age range of children is included.Validation Studies of Electronic BP Monitors in ChildrenAlthough a plethora of electronic BP monitors are currently available in the market, a successful validation study has been reported in 1 protocols. The AAMI or ISO protocol was used in 20 studies (65%), the BHS in 18 (58%), and the European Society of Hypertension International Protocol in 6 studies (19%).Korotkov K5 was used for reference diastolic BP in 14 studies, K4 in 1 study, and 4 studies used K4 or K5 depending on the subject (not reported in 12 studies).Twenty-two studies passed the validation protocol requirements (71%) and 9 (29%) failed (6 for systolic and diastolic BP and 3 for diastolic only). Two devices passed 1 protocol criteria and failed another.33,45Results from children were reported together with those of older subjects (adolescents or adolescents and adults) in 26 studies (84%).Taken together, these data suggest that the published evidence for the accuracy of electronic BP monitors in children is limited and with considerable heterogeneity among studies regarding the population included, the validation protocol and criteria used, the reference method for defining diastolic BP, and the approach for analysis and reporting. Because most of the studies reported results for children together with older subjects, it might be argued that the results for children might have been different in the 2 groups if analyzed separately. An issue is that several studies did not fulfill all the requirements of the validation protocols, and misreporting of crucial data was not uncommon, which is a recognized issue also for such studies in adults.51–53 Moreover, several negative validations are probably not published because the manufacturers prefer to further develop their devices and then retest them (publication bias).Because electronic BP monitors are currently used in children in clinical practice and are supported by pediatric hypertension guidelines1,6 particularly for ambulatory and home BP monitoring, the existing evidence on their accuracy has major implications for clinical practice and research. In an individual child, the BP difference between the 90th and 95th centile (which define normotension, high-normal BP, and hypertension) is only 3 to 4 mm Hg,1 which demonstrates the major practical risks of inaccurate BP measurement. Moreover, it is scientifically problematic that the normalcy tables currently recommended1,6 for the evaluation of ambulatory BP in children are based on a single study54 that used a BP monitor, which has not been successfully validated in children39,45 (Table 2).Optimizing the Validation Procedure for BP Monitors in ChildrenFrom the validation protocols currently used in children (Table 1), the BHS, although it requires specific evaluation of devices in children, does not provide pass criteria because it is an old protocol with the last revision in 1993.19 On the other hand, the European Society of Hypertension International Protocol, which is the most widely used protocol in adults,51 did not specifically address the issue of pediatric validations.21 Thus, the ANSI/AAMI/ISO20 currently is the best available protocol for the validation of BP monitors in children. However, further development is still necessary specifically for children, and a universal protocol needs to be agreed and applied globally.In regard to the sample size required for a validation study in children, there is consensus among the validation protocols that a minimum of N=30 to 35 is needed and that this should be performed after a successful general population study.19–21 However, the ANSI/AAMI/ISO protocol allows a general population study to include 35 children (3–12 years) and 50 older subjects20 and the analysis to include all the 85 subjects together. It might be argued that an automated device might be easier to pass a validation study in children that have smaller arms and lower BP levels. On the other hand, by analyzing data in children together with those in adults, it is possible that a device is inaccurate in children, yet this finding might be diluted by good results in the adults. Among 5 validation studies that provided separate analysis in children (age 3–12 years), only 2 reported a pass result.25,30,38,50 The Spacelabs 90207 ambulatory BP monitor has passed the BHS and the AAMI protocol criteria in adults10 but failed in 2 studies that used the same protocols in children.39,45 The Welch Allyn Vital Signs professional office BP monitor has been successfully validated in adults10 but failed in children.27 Because children constitute a rather heterogeneous population, it is important that the pediatric data are analyzed separately from those in older subjects. Moreover, inclusion criteria for age distribution are needed in pediatric validations to ensure that the entire 3- to 12-year age range is well represented.Both the European and the American guidelines for pediatric hypertension recommend the use of Korotkov sound K5 for the diagnosis of hypertension in children.1,2 Thus, it is an important scientific inconsistency that the ANSI/AAMI/ISO standard recommends K4 for the determination of reference diastolic BP in children.20 It is certainly inappropriate to use K4 for the validation of BP monitors and recommend K5 for diagnosing hypertension in clinical practice. The European and American guidelines base their recommendation on population data in children and risk-associated epidemiological data in adults,1,2 whereas the ANSI/AAMI/ISO standard20 cites a single and old invasive study in children showing K4 to be a better estimate of aortic BP.55 Interestingly, there has been a consistent preference for using K5 in pediatric clinical research, even in validation studies (Table 2).56 This is probably because the between-observers agreement is closer for K5 because the sounds disappearance is easier to define.5,57 This is acknowledged by the ANSI/AAMI/ISO standard, which states that K4 seems to be more difficult to determine and most healthcare personnel are trained to recognize K5.20 However, in cases of children with Korotkov sounds audible at complete deflation or at unphysiologically low levels, K4 should be recorded and reported.The validation procedure is a demanding task and often too difficult for young children. It requires at least 9 sequential BP measurements, which might last longer than 20 minutes, while the child should remain seated without moving or talking.19–21 Thus, a quality check of validation sessions is necessary in children, assessing movement, talking, and other interference that might increase the BP variability.PerspectivesAlthough automated electronic devices are currently recommended and widely used for ambulatory, home, and office BP measurement in children, the published evidence on their accuracy in this population is limited. In most studies, the results in children are uncertain because they were analyzed together with those in older subjects. The current validation protocols do not adequately address all the specific requirements of BP monitors validation in children. There is need for (1) more automated devices to be tested in children; (2) a universal protocol that meets the specific issues of children to be developed, and (3) the review process for publishing validation studies to follow a detailed checklist.DisclosuresG.S. Stergiou has received lecturer fees by Omron and consultation fees by Microlife. The other authors report no conflicts.FootnotesCorrespondence to George S. Stergiou, Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, 152 Mesogion Ave, Athens 11527, Greece. E-mail [email protected]References1. Lurbe E, Agabiti-Rosei E, Cruickshank JK, et al. 2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents.J Hypertens. 2016; 34:1887–1920. doi: 10.1097/HJH.0000000000001039.CrossrefMedlineGoogle Scholar2. 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