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Ambulatory blood pressure monitoring during pregnancy: Establishment of standards of normalcy
LETTERS TO THE EDITOR
AIH 1996;9:1240-1241
Ambulatory Blood Pressure Monitoring During Pregnancy: Establishment of Standards of Normalcy We agree with the conclusions of the paper by Ferguson et al 1 when they suggest that ambulatory blood pressure monitoring has a promising future. There are, however, several aspects of this paper to which we would like to draw attention. There is no reference to parity of the pregnant patients included in this study. This is an important aspect of pregnant patient characterization as not only do hemodynamics vary from the nonpregnant state, but they also vary with different parities. The authors employed an Accutracker II ambulatory blood pressure monitoring device in their study. While there is reference in the article to validation studies carried out on ambulatory monitoring devices during pregnancy, there is no reference to the Accutracker II device having undergone validation in pregnancy using either of the internationally accepted validation protocols for automated instrumentsY The statement that "blood pressure circadian rhythms generally appeared to be similar in all four groups of women" does not appear to be supported by the evidence provided. In addition, there is no description of how the difficult issue of day / night differences was approached. Our group monitored 106 primigravid women who underwent 24-h ambulatory blood pressure measurement using the pregnancy validated SpaceLabs 90207 (Redmond, WA) on five occasions throughout pregnancy. This was a longitudinal study confined to primigravid and white women. In total, 496 24-h recordings were analyzed. We noted that there was a statistically significant rise in both systolic and diastolic blood pressure from 33 weeks gestation. It would appear from our study that any fall in blood pressure in pregnancy must occur very early, rather than (as has been suggested) in the middle trimester. The nocturnal fall in blood pressure was preserved
throughout pregnancy, with a significant difference between daytime and nighttime measurements present on all measurement occasions for systolic, diastolic, and mean blood pressures and heart rate. 4 We agree with Ferguson et al that the clinical value of this sort of normalcy descriptive data will lie in comparing these normal values to data obtained from studying pregnant patients with elevated blood pressures. Although ambulatory blood pressure monitoring does facilitate repeated measurements and redresses the sampling error issue, investigators need to be particularly aware of the pitfalls associated with using devices that have not been validated for use in pregnancy as recommended by the British Hypertension Society protocol,3 and drawing conclusions from studies conducted in nonhomogeneous patient groups in studies that are not longitudinal. REFERENCES
1. Ferguson JH, Neubaur BL, Shaar CJ: Ambulatory blood pressure monitoring during pregnancy: establishment of standards of normalcy. Am J Hypertens 1994;7:838843. 2. American National Standard: Electronic or Automated Sphygmomanometers. Association for the Advancement of Medical Instrumentation, Arlington, Virginia, 1993. 3. O'Brien E, Petrie J, Littler WA, et al: The British Hypertension Society protocol for the evaluation of blood pressure measuring devices. J Hypertens 1993;11(suppl 2) :$43-$63. 4. Halligan A, O'Brien E, O'Malley K, et al: Twenty-four hour ambulatory blood pressure measurement in a primigravid population. J Hypertens 1993;11:869- 873. AIDAN HALLIGANAND E. O'BRIEN From the Umversityof Leicester,England. Address correspondenceand reprint requests to Aidan Halligan, MD, University of Leicester, Clinical Sciences Building, Leicester Royal Infirmary,PO Box 65, LeicesterLE2 7LX,England.
Ambulatory Blood Pressure Monitoring in Patients With Single Chamber Ventricular Pacemakers (VVI Pacing Mode) Ambulatory blood pressure monitoring (ABPM) devices are now being used increasingly in the assessment of hypertensive patients, but those with pace© 1996 by the American Journal off Hypertension, Ltd. Published by Elsevier Science, Inc.
makers and arrhythmias, such as atrial fibrillation, are usually excluded as the accuracy of the devices in such patients is unknown. A recent report suggests 0895-7061/96/$15.00 PII S0895-7061¢96J00393-7
AIH 1996;9:1240-1241
Ambulatory Blood Pressure Monitoring During Pregnancy: Establishment of Standards of Normalcy We agree with the conclusions of the paper by Ferguson et al 1 when they suggest that ambulatory blood pressure monitoring has a promising future. There are, however, several aspects of this paper to which we would like to draw attention. There is no reference to parity of the pregnant patients included in this study. This is an important aspect of pregnant patient characterization as not only do hemodynamics vary from the nonpregnant state, but they also vary with different parities. The authors employed an Accutracker II ambulatory blood pressure monitoring device in their study. While there is reference in the article to validation studies carried out on ambulatory monitoring devices during pregnancy, there is no reference to the Accutracker II device having undergone validation in pregnancy using either of the internationally accepted validation protocols for automated instrumentsY The statement that "blood pressure circadian rhythms generally appeared to be similar in all four groups of women" does not appear to be supported by the evidence provided. In addition, there is no description of how the difficult issue of day / night differences was approached. Our group monitored 106 primigravid women who underwent 24-h ambulatory blood pressure measurement using the pregnancy validated SpaceLabs 90207 (Redmond, WA) on five occasions throughout pregnancy. This was a longitudinal study confined to primigravid and white women. In total, 496 24-h recordings were analyzed. We noted that there was a statistically significant rise in both systolic and diastolic blood pressure from 33 weeks gestation. It would appear from our study that any fall in blood pressure in pregnancy must occur very early, rather than (as has been suggested) in the middle trimester. The nocturnal fall in blood pressure was preserved
throughout pregnancy, with a significant difference between daytime and nighttime measurements present on all measurement occasions for systolic, diastolic, and mean blood pressures and heart rate. 4 We agree with Ferguson et al that the clinical value of this sort of normalcy descriptive data will lie in comparing these normal values to data obtained from studying pregnant patients with elevated blood pressures. Although ambulatory blood pressure monitoring does facilitate repeated measurements and redresses the sampling error issue, investigators need to be particularly aware of the pitfalls associated with using devices that have not been validated for use in pregnancy as recommended by the British Hypertension Society protocol,3 and drawing conclusions from studies conducted in nonhomogeneous patient groups in studies that are not longitudinal. REFERENCES
1. Ferguson JH, Neubaur BL, Shaar CJ: Ambulatory blood pressure monitoring during pregnancy: establishment of standards of normalcy. Am J Hypertens 1994;7:838843. 2. American National Standard: Electronic or Automated Sphygmomanometers. Association for the Advancement of Medical Instrumentation, Arlington, Virginia, 1993. 3. O'Brien E, Petrie J, Littler WA, et al: The British Hypertension Society protocol for the evaluation of blood pressure measuring devices. J Hypertens 1993;11(suppl 2) :$43-$63. 4. Halligan A, O'Brien E, O'Malley K, et al: Twenty-four hour ambulatory blood pressure measurement in a primigravid population. J Hypertens 1993;11:869- 873. AIDAN HALLIGANAND E. O'BRIEN From the Umversityof Leicester,England. Address correspondenceand reprint requests to Aidan Halligan, MD, University of Leicester, Clinical Sciences Building, Leicester Royal Infirmary,PO Box 65, LeicesterLE2 7LX,England.
Ambulatory Blood Pressure Monitoring in Patients With Single Chamber Ventricular Pacemakers (VVI Pacing Mode) Ambulatory blood pressure monitoring (ABPM) devices are now being used increasingly in the assessment of hypertensive patients, but those with pace© 1996 by the American Journal off Hypertension, Ltd. Published by Elsevier Science, Inc.
makers and arrhythmias, such as atrial fibrillation, are usually excluded as the accuracy of the devices in such patients is unknown. A recent report suggests 0895-7061/96/$15.00 PII S0895-7061¢96J00393-7