Noninvasive assessment of blood pressure variability in preterm infants

The feasibility of measuring blood pressure (BP) variability by a noninvasive beat-to-beat finger arterial BP device (Finapres) was assessed in preterm infants. By application of the finger cuff around the infant's wrist, time and frequency domain (spectral power) analysis of noninvasive beat-to-beat BP signals were compared with intra-arterial measurements. A fast Fourier Transform was used to compute the spectral power density from 128-s periods. The low-frequency band (LF; 0.04-0.15 Hz) is partly associated with baroreflex activity. The high-frequency band (HF; 0.4-1.5 Hz) is associated with respiratory activity. In eight subjects above 1000 g, reliable signals could be obtained. We observed a high correlation between noninvasive and intra-arterial beat-to-beat systolic BP values (mean r value +/- SD, 0.87 +/- 0.11), with a gain close to 1 (mean gain +/- SD, 1.0 +/- 0.4 mm Hg/mm Hg). Finapres estimated beat-to-beat systolic BP changes more accurately than diastolic values. We found a very high amount of linear coupling, expressed as coherence function, between the power spectra of noninvasive and intra-arterial systolic BP measurements. For systolic BP, the (pooled) group mean +/- SEM coherence values were 0.93 +/- 0.00 and 0.91 +/- 0.01 for LF and HF fluctuations, respectively (NS). The wrist method of Finapres in neonates has limited value in estimating absolute BP but is useful in a clinical research situation, where identification of beat-to-beat changes in systolic BP is more important. Finapres provides a noninvasive tool for investigating autonomic cardiovascular regulation (baroreflex sensitivity, spectral analysis of BP fluctuations) in neonates.     

Delivery room blood pressure percentiles of healthy,singleton, liveborn neonates

Background: Arterial blood pressure (BP) is one of the four vital signs that reflect cardiovascular status in neonates. The present study aimed to obtain BP percentiles among healthy, singleton, liveborn neonates between 34 and 43 weeks of gestation who were less than 1 h old. Methods: BP measurements were taken after birth in supine‐positioned neonates in the delivery room using an oscillometric device. A total of 982 well‐nourished neonates who did not require resuscitation, were not fetally malnourished, were not admitted to the neonatal intensive care unit and were without obvious congenital abnormalities were included in the study. Results: Sex‐ and type‐of‐delivery‐specific 5th and 95th percentiles BP measurements were obtained for gestation. Mean BP values for systolic, diastolic and mean of term neonates were 63.98 ± 12.29 mmHg, 38.34 ± 11.06 mmHg and 49.32 ± 11.33 mmHg, and late preterm neonates were 61.80 ± 12.46 mmHg, 33.17 ± 9.97 mmHg and 46.52 ± 10.8 mmHg, respectively. There were weak but significant correlations between birthweight, birth length and head circumference and systolic, diastolic and mean arterial BP values (r = 0.20, r = 0.15 and r = 0.20, respectively, P < 0.001). Neonates who were delivered vaginally had higher mean BP values for systolic, diastolic and mean than neonates delivered by cesarean section (P < 0.05). Female neonates had higher systolic BP values than male neonates (P < 0.05). Conclusion: Data presented in this study include sex‐ and delivery‐mode‐specific BP percentile curves using an oscillometric method and serve as a valuable reference for physicians in dealing with the management of singleton, liveborn late preterm and term newborns in the delivery room intensive care.     

Indirect BP monitoring in the newborn. Evaluation of a new oscillometer and comparison of upper- and lower-limb measurements

We compared simultaneous direct (aortic) and indirect (oscillometric) BP measurements in 19 patients admitted to a newborn intensive care unit. Two hundred six indirect measurements were obtained from an upper extremity in 14 patients, and 50 from a lower extremity in five other patients. A regression analysis of paired data over a wide range of BPs showed excellent correlation between measurements obtained with the automated oscillometer and intra-arterial catheters. The oscillometric BP correlated equally well in both upper and lower extremities. Simultaneous upper- and lower-extremity BP measurements were taken in seven infants with low birth weights during the first 12 days of life and in ten normal term 2-to 5-day-old infants. Contrary to some previous reports, systolic, mean, and diastolic pressures were virtually identical at both sites.     

Comparison between oscillometric and invasive blood pressure measurements in critically ill premature infants

Aim: Blood pressure (BP) measurement techniques in neonates generally involve noninvasive measurements with a cuff (oscillometric) or invasive measurements through an arterial catheter. The aim of this study was to determine the reliability of the noninvasive oscillometric method in critically ill preterm infants when results were compared with the invasive technique. Method: Twenty‐seven premature infants with a mean birth weight of 1138 ± 552 g were enrolled in the prospective study. Invasive and noninvasive mean arterial pressure (MAP) levels were recorded simultaneously at each measurement in all patients. Low or lower range mean invasive MAP values (MAP ≤30) were evaluated separately as we aimed to assess the value of noninvasive measurements in hypotensive sick premature infants. Results: Totally, 431 paired BP measurements were taken during the first week of life. There was no statistically significant difference between invasive and noninvasive readings. However, noninvasive measurements were found significantly higher compared with invasive measurements in the presence of hypotension (p < 0.05). Conclusion: This study showed good agreement between oscillometric and invasive readings in critically ill premature infants, and further, comparable mean MAP values were found with the two methods. However, the accuracy of the oscillometric BP measurement technique fails in preterm infants with BP within the lower limits.     

Systolic and diastolic blood pressure levels of healthy newborn infants

OBJECTIVE: To identify normative blood pressure (BP) levels for Brazilian newborn infants and to define a cut-off point for high systolic and diastolic BP in this population.METHODS: 634 healthy term neonates, aged 12 to 36 hours, who were born in the Instituto Materno Infantil de Pernambuco (IMIP) were included in this survey. An oscillometric method was used to acess the neonates BP. To identify high BP levels the Second Task Force definition was applied.RESULTS AND CONCLUSIONS: The normative BP values for the study sample was 82.0 -/+ 7.5 mmHg for systolic and 41.7 -/+ 5.8 mmHg for diastolic blood pressure. The cut-off points for high blood pressure were >/= 95 mmHg and >/= 52 mmHg for systolic and diastolic blood pressure respectively. These results are similar to those reported in other surveys done in other countries.     

Upper- vs lower-limb systolic blood pressure in full-term normal newborns

The difference between upper- vs lower-limb systolic blood pressure (BP) was investigated in 100 normal full-term newborns younger than 24 hours of age by the oscillometric method. The mean systolic BP of both upper limbs was 72.3 +/- 7.6 mm Hg (mean +/- SD). The mean +/- SD systolic BP of both lower limbs was 71.3 +/- 8.2 mm Hg. Systolic BP in the upper limb was greater than that in the lower limb in 66% of newborns by as much as 20 mm Hg (mean +/- SD, 3.5 +/- 3.1). Systolic upper-limb BP was lower than systolic lower-limb BP in 28% of newborns by as much as 21 mm Hg (mean +/- SD, 5.1 +/- 5.1). Systolic BP did not correlate with birth weight. Follow-up evaluation of BP in 25 of the infants up to 3 years of age revealed higher systolic BP in the lower extremities in 24 of the 25 infants. We conclude that (1) it is normal to have a higher systolic BP in either the upper limb or the lower limb in newborns younger than 24 hours of age, and (2) there is no correlation of systolic BP with birth weight in full-term normal neonates younger than 24 hours of age.     

Reliability of the Dinamap non-invasive monitor in the measurement of blood pressure of ill Asian newborns

Four hundred thirty-one paired sets of readings of systolic and diastolic blood pressure and 438 paired sets of readings of mean arterial BP from 49 ill newborns, including 21 very low birth weight infants, were analyzed for the extent and pattern of agreement and the linear relationship between the Dinamap oscillometric monitor and the direct intraarterial blood pressure readings. Agreement between the two methods was measured by the intraclass correlation, whereas the linear relationship was assessed by the product-moment correlation. The intraclass correlations for systolic, diastolic and mean blood pressures were 0.696, 0.766, and 0.781, respectively. The product-moment correlations for systolic, diastolic and mean blood pressures were 0.706, 0.768, and 0.786, respectively. BP measurements by the Dinamap monitor showed reasonably close agreement to those obtained by the intraarterial mean arterial pressure ranges above 40 mmHg. For mean arterial pressure of 40 mmHg and lower, BP readings by the Dinamap monitor tended to be higher than those obtained by the intraarterial method. These findings appeared to be consistent regardless of the birth weight of the newborn.     

新生儿血压节律及窒息或早产因素对血压节律影响的研究

目的了解正常新生儿生后早期(48h内)血压是否存在昼夜节律变化规律,以及窒息或早产因素对血压节律的影响.方法对106例正常足月自然分娩新生儿、30例足月重度窒息儿(1分钟Apgar评分<3分)及28例早产儿于生后48h内的测量血压,选择生后2、6、10、14、18、22时为测量时间点.结果正常足月自然分娩新生儿生后早期各时间点血压值(包括收缩压、舒张压和平均动脉压,下同)差异有显著性 ([ WTBX〗P均<0.05),表现为生后2时最低,6～10时升至最高,在14时有一低谷,在18 时又有一小高峰,至22时又下降.窒息组及早产组生后48h内各时间点血压值差异无显著性(窒息组 P分别为0.650、0.943和0.912,早产组P分别为0.283、0.575和0.327).结论正常足月自然分娩新生儿生后早期血压有昼夜节律变化,重度窒息儿及早产儿在生后早期未出现血压昼夜节律变化.     

Determinants of blood pressure in very low birth weight neonates: lack of effect of antenatal steroids

OBJECTIVES: To define the range of normal blood pressures (BP) for very low birth weight (VLBW;相似文献   

Accuracy of blood pressure measurement by the Dinamap monitor in infants and children

Indirect BPs measured by the Dinamap monitor, an oscillometric device, and the conventional auscultatory method were compared with the direct radial artery pressure in infants and children. There were 29 patients in the Dinamap group with a median age of 18 months (ranges 1 month to 16 years) and 20 patients in the auscultatory group with a median age of 3.5 years (ranges 3 months to 16 years). The direct radial artery pressures were recorded on a strip chart and the ranges of pressures were obtained for systolic, diastolic, and mean pressures. The range of the direct readings was converted to a weighted single reading, and comparisons were made between the direct and indirect readings. The linear regression equation between the direct (x) and the Dinamap (y) readings (with correlation coefficient) was y = 1.05x - 5.36 (r = .97) for systolic, y = 1.10x - 4.65 (r = .903) for diastolic, and y = 1.06x - 4.21 (r = .917) for mean pressures. The linear regression equation (with correlation coefficient) for the auscultatory pressure was y = 1.60x - 68.23 (r = .872) and y = 1.38x - 16.47 (r = .874) for diastolic pressures. The error was defined as the indirect reading minus the direct reading. The mean error +/- SD was -0.24 +/- 3.26 for systolic, 1.28 +/- 4.74 for diastolic, and 0.10 +/- 4.56 mm Hg for mean pressures by the Dinamap method. It was -1.65 +/- 6.68 for systolic, and 8.70 +/- 5.97 for diastolic pressures by the auscultatory method.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feasibility of noninvasive continuous finger arterial blood pressure measurements in very young children, aged 0-4 years

Our goal was to study the feasibility of continuous noninvasive finger blood pressure (BP) monitoring in very young children, aged 0-4 y. To achieve this, we designed a set of small-sized finger cuffs based on the assessment of finger circumference. Finger arterial BP measured by a volume clamp device (Finapres technology) was compared with simultaneously measured intra-arterial BP in 15 very young children (median age, 5 mo; range, 0-48), admitted to the intensive care unit for vital monitoring. The finger cuff-derived BP waveforms showed good resemblance with the invasive arterial waveforms (mean root-mean-square error, 3 mm Hg). The correlation coefficient between both methods was 0.79 +/- 0.19 systolic and 0.74 +/- 0.24 diastolic. The correlation coefficient of beat-to-beat changes between both methods was 0.82 +/- 0.18 and 0.75 +/- 0.21, respectively. Three measurements were related to measurement errors (loose cuff application; wrong set-point). Excluding these erroneous measurements resulted in clinically acceptable measurement bias (-3.8 mm Hg) and 95% limits of agreement (-10.4 to + 2.8 mm Hg) of mean BP values. We conclude that continuous finger BP measurement is feasible in very young children. However, cuff application is critical, and the current set-point algorithm needs to be revised in very young children.     

Differences in blood pressure levels obtained by auscultatory and oscillometric methods

Levels of blood pressure measured by the conventional auscultatory method were compared with those measured by the Dinamap Monitor (Dinamap Monitor 1846 SX, Critikon Inc, Tampa, Fla), an oscillometric device. Triplicate measurements were obtained by the two methods 10 to 15 minutes apart in 381 seated fifth-grade children, ages 10 to 13 years. The width of the air bladder of the blood pressure cuff was selected to be 40% to 50% of the circumference of the upper arm. The mean systolic and diastolic pressures (at the fourth phase of Korotkoff sounds) by the auscultatory method were 6.4 mm Hg lower and 8.7 mm Hg higher than the oscillometric systolic and diastolic blood pressures, respectively. The findings of this study suggest that published normative levels of auscultatory blood pressure may be inappropriate as a standard when blood pressure measurement is obtained by the Dinamap Monitor. Until a new set of normative Dinamap blood pressure levels becomes available, one should use equations (A = 12.8 + 0.82D for systolic, and A = 34.3 + 0.54D for diastolic blood pressures at the fourth phase of Korotkoff sounds, where A is auscultatory blood pressure and D is Dinamap blood pressure) to predict auscultatory blood pressures before Dinamap blood pressures are compared with normative auscultatory blood pressure levels.     

Non-invasive oscillometric measurement of systolic,mean and diastolic blood pressure in infants with congenital heart defects after operation. A comparison with direct blood pressure measurements

The accuracy of indirect oscillometric blood pressure measurements has been evaluated in 32 infants up to 11 months of age undergoing heart surgery. In a number of 1029 simultaneous measurements the indirect blood pressure was compared with the direct value obtained from a radial artery catheter. Cuffs of different sizes were applied. The main results were as follows: (1) Regarding the ratio of cuff width to arm circumference, the best correlation between oscillometric and direct blood pressure measurements was obtained with a ratio of 0.38–0.41. (2) The value of indirect blood pressure measurements depends on the absolute height of the blood pressure. In low blood pressure there is a tendency to underestimate and in high blood pressure there is a tendency to overestimate by the oscillometric blood pressure measurement.By applying an appropriate cuff size and by using our diagrams it should be possible to derive a direct value for the blood pressure on the basis of indirect oscillometric blood pressure measurements.Abbreviations BP blood pressure - BPM blood pressure measurements - CW/ArmC cuff width to arm circumference ratio - DAP diastolic arterial pressure - MAP mean arterial pressure - SAP systolic arterial pressure - ME mean error - SD standard deviation Research fellow supported by the A. v. Humboldt Stiftung     

Oscillometric and intra-arterial blood pressure measurements in the neonate: a comparison of methods

ABSTRACT. A number of methods exist to measure neonatal blood pressure, one of which involves oscillometric principles. This method is the functional basis of the Dinamap 847 which has been studied for accuracy and reproductibility in 398 paired comparisons with direct arterial measurements in nine neonates. The correlation between the Dinamap and direct arterial pressure values were excellent, although for systolic blood pressure the Dinamap tends to underestimate by 2.4 ± 3.9 mm Hg. The present study has shown the Dinamap to be a clinically reliable instrument for measuring neonatal blood pressure.     

Normative arm and calf blood pressure values in the newborn

Indirect BP measurement was obtained in the right upper arm in 219 healthy newborn infants with the Dinamap monitor and was compared with values obtained from the calf to establish normative BP values and to help establish a diagnosis of hypertension and coarctation of the aorta in the newborn. There were 174 Mexican-Americans (79.5%), 33 whites (15.0%), and 12 blacks (5.5%). The width of the BP cuff was selected to be 0.4 to 0.5 times the circumference of the extremities. Three supine position readings of BPs and heart rate were obtained from each site and were averaged for statistical analyses. Mean arm BP values (+/- SD) of the neonate less than 36 hours of age were 62.6 +/- 6.9/38.9 +/- 5.7 mm Hg (48.0 +/- 6.2 mm Hg). Neonates older than 36 hours had slightly but significantly (P less than .05) greater values (4 to 6 mm Hg) than did infants younger than 36 hours of age. Active neonates had values 6 to 10 mm Hg greater than quiet neonates (P less than .05). BP values in the calf obtained with the same-sized cuff were almost identical with those obtained from the arm. Differences in consecutively obtained arm and calf BPs (arm values minus calf values) were 1.1 +/- 7.7 mm Hg systolic, -0.01 +/- 6.2 mm Hg diastolic, and 0.9 +/- 6.9 mm Hg mean pressures. Mean heart rate (+/- SD) of neonates less than 36 hours of age was 129.4 +/- 13.2 beats per minute and that of neonates older than 36 hours of age was 139.4 +/- 14.1 beats per minute.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular effects of nasogastric tube feeding in the healthy preterm infant

Th systemic blood pressure (BP) and heart rate were estimated by the neonatal Dinamap 847 in 16 healthy preterm neonates in active sleep (AS) before, during and after milk feed by indwelling nasogastric tube. The mean arterial blood pressure (MAP) rose by 10.2% (P less than 0.01) and the diastolic pressure by 8.3% (P less than 0.05) during feeding. The systolic and pulse pressures also rose but individual variation rendered these changes insignificant. The heart rate increased by 6.3% (P less than 0.05) 10 min after the end of the feed. The degree of change in BP and heart rate was unrelated to body weight, gestational age, postnatal age, rate of feeding, volume or duration of the feed.     

Use of pulse oximetry for blood pressure measurement after cardiac surgery

Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.     

Arterial Blood Pressure in the Very Low Birthweight Neonate

ABSTRACT. The noninvasive oscillometric technique of arterial blood pressure determination was evaluated in fifteen very low birth weight neonates (<1400 g). Measurement of invasive umbilical artery catheter pressure was used as a reference standard. By using a cuff width to arm circumference ratio of 0.33–0.42, mean blood pressure was overestimated by 6.2 (7.2) mmHg (mean and 1 SD), p <0.001. More accurate mean blood pressure measurements were recorded with a cuff width to arm circumference ratio of 0.44–0.55. Measurements of systolic and diastolic blood pressure showed similar results.     

Use of pulse oximetry for blood pressure measurement after cardiac surgery

Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.

     

Arterial blood pressure in the very low birthweight neonate. Evaluation of an automatic oscillometric technique

The noninvasive oscillometric technique of arterial blood pressure determination was evaluated in fifteen very low birth weight neonates (less than 1,400 g). Measurement of invasive umbilical artery catheter pressure was used as a reference standard. By using a cuff width to arm circumference ratio of 0.33-0.42, mean blood pressure was overestimated by 6.2 (7.2) mmHg (mean and 1 SD), p less than 0.001. More accurate mean blood pressure measurements were recorded with a cuff width to arm circumference ratio of 0.44-0.55. Measurements of systolic and diastolic blood pressure showed similar results.