Accurate measurement of intraarterial pressure through radial artery catheters in neonates

A technique is described for accurate measurement of intraarterial pressure through radial artery catheters in neonates. The technique, which can be used for short-term monitoring, uses cannulation of the radial artery with a 24-gauge Teflon catheter, connected by a Luer-Lok fitting to a threeway stopcock and a high-fidelity tip transducer. In vitro studies showed that the system is linear and the frequency response is flat (±3 dB) up to 50 Hz. The technique permits gathering of high-quality pressure data and can be used in the area of neonatal clinical research for short-term monitoring. It needs to be developed further before routine application in clinical practice can be recommended.     

Noninvasive continuous blood pressure measurement: A clinical evaluation of the Cortronic APM 770

The Cortronic APM 770 (Cortronic, Ronkonkoma, NY) is a commercial device that claims to measure blood pressure noninvasively and continuously with the use of a standard blood pressure cuff. The aim of our study was to assess the performance of the continuous-mode blood pressure readings of the Cortronic during anesthesia and surgery. We recorded blood pressure in 5 patients bilaterally. An intraarterial pressure (IAP) curve was recorded from 1 arm and the Cortronic pressure curve (CPC) was recorded from the other. For statistical analysis the period between 2 Cortronic recalibrations was defined as the intercalibration interval. The duration of these intervals ranged from 20 to 0.5 minutes. Four paired samples were drawn from each interval. The first sample in an interval represented the recalibration blood pressure; the other samples represented the continuous blood pressure. A total of 1,232 samples were taken, of which 308 were recalibration. The median of the differences and the 2.5th and 97.5th percentile limits of agreement were determined. Their respective values for diastolic and systolic recalibration measurements were 5, –17, and 34 mm Hg, and 6, –12, and 38 mm Hg. Their values for continuous measurements were 4, –23.5, and 32 mm Hg, and 6, –30, and 70 mm Hg. Changes in CPC were evaluated against changes in the corresponding IAP by plotting them in 4-quadrant graphs. In these graphs the Spearman rank correlations were betweenr=–0.17 andr=0.01. We observed opposite CPC and IAP trends on 24 occasions during this study. We performed a simple simulation study to better understand the measurement method of the Cortronic. The study showed a positive relationship between pulsation volume and CPC amplitude, and between pulsation rate and CPC amplitude. We conclude that during anesthesia and surgery continuous-mode blood pressure readings of the Cortronic are unreliable, and suggest that the phenomenon of the two pressures' moving in opposite directions is inherent to the measurement principles of the device.     

Availability of intraarterial pressure waveforms from catheter-manometer systems during surgery

We determined how often and for how long usable pressure waveforms were unavailable from a radial intraarterial pressure cannula during anesthesia and surgery in 41 patients. During cardiac surgery with a continuous flush system, usable arterial pressure was unavailable 8.7% of the time. It was unavailable 9.1% of the time during noncardiac surgical procedures with a continuous flush system, and 14.7% of the time in systems without continuous flush. Thus, the use of a continuous flush device improves intraarterial pressure availability. Artifact is the principal contributor to unavailability, followed by flushing and blood sampling. With rare exceptions the use of a Riva-Rocci cuff for occasional return-to-flow maneuvers on the same arm as the intraarterial cannula reduces intraarterial pressure availability only slightly, certainly not enough to detract from its usefulness in providing an estimation of systolic pressure during intraarterial pressure monitoring.     

Accuracy of four indirect methods of blood pressure measurement,with hemodynamic correlations

In 38 adults undergoing cardiac surgery, 4 indirect blood pressure techniques were compared with brachial arterial blood pressure at predetermined intervals before and after cardiopulmonary bypass. Indirect blood pressure measurement techniques included automated oscillometry, manual auscultation, visual onset of oscillation (flicker) and return-to-flow methods. Hemodynamic measurements or calculations included heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect and intraarterial blood pressure values were compared by simple linear regression by patient and measurement period. Measurement errors (arterial minus indirect blood pressure) were calculated, and stepwise regression assessed the relationship between measurement error and heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect to intraarterial blood pressure correlation coefficients varied over time, with the strongest correlations often occurring at the first and last measurement periods (preinduction and 60 minutes after cardiopulmonary bypass), particularly for systolic blood pressure. Within-patient correlations between indirect and arterial blood pressure varied widely—they were consistently high or low in some patients. In other patients, correlations were especially weak with a particular indirect blood pressure method for systolic, mean, or diastolic blood pressure; in some cases indirect blood pressure was inadequate for clinical diagnosis of acute blood pressure changes or trends. The mean correlations between indirect and direct blood pressure values were, for systolic blood pressure: 0.69 for oscillometry, 0.77 for auscultation, 0.73 for flicker, and 0.74 for return-to-flow; for mean blood pressure: 0.70 for oscillometry and 0.73 for auscultation; and for diastolic blood pressure: 0.73 for oscillometry and 0.69 for auscultation. The mean measurement errors (arterial minus indirect values) for the individual indirect blood pressure methods were, for systolic: 0 mm Hg for oscillometry, 9 mm Hg for auscultation, -5 mm Hg for flicker, 7 mm Hg for return-to-flow; for mean: -6 mm Hg for oscillometry, and -3 mm Hg for auscultation; and for diastolic: -9 mm Hg for oscillometry and -8 mm Hg for auscultation. Mean measurement error for systolic blood pressure was thus least with automated oscillometry and greatest with manual auscultation, while standard deviations ranging from 9 to 15 mm Hg confirmed the highly variable nature of single indirect blood pressure measurements. Except for oscillometric diastolic blood pressure, a combination of systemic hemodynamics (heart rate, stroke volume index, systemic vascular resistance index, and cardiac index) correlated with each indirect blood pressure measurement error, which suggests that particular numeric ranges of these variables minimize measurement error. This study demonstrates that striking variability occurs in the relationship between indirect and arterial blood pressure measurements, and that the systemic hemodynamic state influences accuracy of indirect blood pressure measurements. When the reproducibility of repeated indirect blood pressure measurements appears unsatisfactory or inconsistent with other clinical observations, clinicians may find that an alternative indirect blood pressure method is a better choice. Of the methods tested, no single indirect blood pressure technique showed precision superior to the others, but two methods yielded data only for systolic pressure. These findings lend support to intraarterial blood pressure measurement in conditions of hemodynamic variability, and suggest the theoretical benefits of continuous indirect blood pressure measurements. Annual meeting of the American Society of Anesthesiologists, New Orleans, LA, Oct 1984.     

Dynamic response of a neonatal catheter-manometer system in situ

Objective. The purpose of this study was to develop, validate, and apply a flush-pulse method to determine the dynamic response of a neonatal catheter-manometer system (CMS) in situ.Methods. In the flush-pulse method, the opened fast-flush valve of the CMS is closed; as a result, the fluid column in the CMS is impacted. This procedure can be done without affecting the net flow of infusion fluid. We validated the method in laboratory conditions by comparing 14 paired results obtained with this method to the results obtained using a generally accepted step-response method. The measurable values are the resonance frequency (f_r) and the damping coefficient (). The analysis of the flush-pulse method in situ is complicated by the patient's blood pressure wave. A remedy for this problem that is based on the first derivative of the pressure signal has been developed. The flush-pulse method is applied 14 times in situ.Results. In laboratory settings, the f_r ranged from 12.5 to 64.0 Hz and ranged from 0.14 to 0.32. The correlation coefficient was 0.99 for f_r and 0.91 for . We found four overdamped systems in situ (>1). In other systems f_r values between 8.5 and 41.0 Hz and values between 0.16 and 0.72 were observed. The dynamic response in situ appeared to deteriorate with time due to routine intensive care procedures.Conclusions. The flush-pulse method proved to be a valid test for determining the dynamic response. The results obtained in situ emphasize the need for a regular evaluation of the dynamic response of the neonatal CMS in order to assess the shape of the pressure wave.The authors are grateful to F. van Nijmweegen and R. Smeets of the Laboratory Automation Group of the Eindhoven University of Technology for their implementation of the data acquisition system.     

Elevated pulmonary capillary wedge pressure in a patient with hypovolemia

Since its introduction in 1969, the balloon-tipped pulmonary artery catheter has become widely accepted. Pulmonary capillary wedge pressures have been used diagnostically to determine left ventricular preload and volume status. We report on a patient with noncardiogenic pulmonary edema, secondary to a heroin overdose, who was hypovolemic and had an elevated pulmonary capillary wedge pressure. We discuss possible explanations and present evidence that the pulmonary capillary wedge pressure does not always accurately reflect volume status.     

The relative accuracies of two automated noninvasive arterial pressure measurement devices

We compared the accuracies of two types of noninvasive blood pressure devices. Thirty-two patients requiring an intraarterial catheter for anesthetic management underwent simultaneous monitoring with Dinamap 1846SX and Ohmeda Finapres 3700 devices. For the first 10 minutes of recording, new Dinamap determinations were performed every 60 seconds; subsequent recordings were made at 3-minute intervals. Data were obtained at the time of new Dinamap readings, and twice between new readings to approximate the real-time performance of the two monitors. We defined superior accuracy as a statistically significant difference in mean absolute error greater than 5 mm Hg. With these criteria, pooled data from all patients revealed no difference in performance, even in real time. Pooled data can be misleading since there was a significant amount of variation in accuracy for both monitors. Therefore, we used nonparametric analysis to determine how many individual patients were monitored better by either device. When we compared only data from new Dinamap readings, the Finapres monitor showed superior performance for systolic readings in 13 patients, versus 6 patients for the Dinamap (P<0.05, chi-square test). Similar analysis for diastolic and mean pressure performance did not reach statistical significance. However, in real time, the Finapres unit monitored more patients more accurately for systolic (14 Finapres versus 3 Dinamap), diastolic (11 Finapres versus 3 Dinamap), and mean (10 Finapres versus 3 Dinamap) pressure determinations. The magnitude of these differences were, however, less dramatic than expected. This was probably due to stabilization of arterial pressure during the anesthetic, which minimized the error due to intermittent sampling. We conclude that continuous Finapres readings and new Dinamap determinations are equally accurate for diastolic and mean arterial pressures. The accuracy of Finapres appears to be slightly superior for systolic pressure. The intermittent sampling of oscillometric devices compromises their performance relative to the Finapres in many, but not all, cases.Presented in part at the annual meeting of the American Society of Anesthesiologists, San Francisco, Oct 1988.     

肱动脉血压测量方法的研究

目的探讨以病人为中心、方便临床、有效的肱动脉血压测量方法。方法将符合实验纳入标准的1 153人随机分为三组,每组进行两次肱动脉血压测量,两次测量间无时间间隔。对照组:标准方法测量两次;实验Ⅰ组:先按标准方法再用实验Ⅰ法测量;实验Ⅱ组:先按标准方法再用实验Ⅱ法测量。比较每组两次测的血压值,采用U检验;再比较实验组与对照组的两次血压测量差值,采用U检验;然后将实验组与对照组两次测量差值的波动范围进行比较,采用χ2检验。结果每组两次测得的血压值比较均P0.05;测量差值比较:实验Ⅰ组与对照组比较P0.05,实验Ⅱ组与对照组比较P0.05;差值波动范围比较:除实验Ⅰ组与对照组在舒张压≤10 mmHg比较P0.05,余均P0.05。结论用实验法测量肱动脉血压对结果无影响,但应优选实验Ⅱ法,需要时用实验Ⅰ法。     

The effect of cuff pressure deflation rate on accuracy in indirect measurement of blood pressure with the auscultatory method

The importance of cuff deflation rate in the auscultatory method of measuring blood pressure was investigated using a computer-based model. To determine the relationship between the cuff deflation rate and the measurement error, two cuff deflation protocols were used, one based on heart rate (mm Hg per heartbeat), the other on a constant rate (mm Hg per second). The different deflation protocols and rates were tested using a constant blood pressure of 120/80 mm Hg and heart rates ranging from 40 to 120 beats/min. It was confirmed that a cuff deflation rate that is time based will introduce larger errors at low heart rates. Using heart rate as a basis for cuff deflation rate yields a constant error that is independent of heart rate. The currently used standard of 3 mm Hg/s could result in a maximum error of 2.5 mm Hg in both systolic and diastolic pressures at a heart rate of 72 beats/min. The maximum systolic and diastolic errors increase to more than 4 mm Hg at 40 beats/min. A deflation rate of 2 mm Hg/beat, however, yields a maximum error of 2 mm Hg for both systolic and diastolic pressures, independent of heart rate. A cuff deflation rate based on heart rate is recommended to help minimize changes in measurement error when measuring blood pressure if a wide range of heart rates will be encountered.Supported by grants from IVAC, San Diego, CA, and Physio Control, Redmond, WA.     

The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure

Objective. The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space.Methods. Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vsU-tube manometers.Results. The three catheters had high damping coefficients () (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r=0.99;p<0.001). Using theU-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H₂O. The rate of rise in theU-tube manometer pressure was limited by the rate of fluid flow through the catheters.Conclusions. We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium madeU-tube manometry unsuitable for clinical use.

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Kurzfassung Ziel. Ziel dieser Untersuchung war die Bestimmung der Genauigkeit von Drucksignalen, die durch lange, enge, in den lumbalen Intrathekalraum eingeführte (Epidural-) Katheter übermittelt werden.Methoden. Unter Verwendung eines Wirbelkanalmodells prüften wir drei Epiduralkatheter: 20-G Arrow, 20-G Abbott und 21-G Portex. Wir bestimmten Dämpfungsfaktor und Eigenfrequenz der drei Katheter, korrelierten die bei der Verwendung dieser drei Katheter gemessenen statischen Drücke im Vergleich zum tatsächlichen Druck im Intrathekalraum und verglichen die Ansprechzeit der drei an Umwandler angeschlossenen Katheter mit der vonU-Rohr-Manometern.Ergebnisse. Die drei Katheter hatten hohe Dämpfungsfaktoren (Arrow, 0,75; Abbott, 0,85; Portex, 1,10) und niedrige Eigenfrequenzen (Arrow, 15,23 Hz; Abbott, 12,83 Hz; Portex, 9,09 Hz). Die dynamischen Ansprechmerkmale des Katheters mit dem größten Innendurchmesser (Arrow 20-G) reichten für eine verläßliche Wiedergabe des pulsierenden zerebrospinalen Flüssigkeitsdrucks aus. Kleinere Katheter hielten den mittleren Druck, obwohl die Oszillationen gedämpft waren. Messungen des statischen Drucks bei allen drei Kathetern zeigten eine gute Korrelation mit den Prüfdrücken (r=0,99;p<0,001). Bei der Verwendung desU-Rohr-Manometers benötigten die Portex-, Abbott- und Arrow-Katheter 170, 140 bzw. 130 Minuten, um mit einem Prüfdruck von 30 cm Wasser ins Gleichgewicht zu kommen. Die Druckanstiegsrate imU-Rohr-Manometer wurde durch die Flüssigkeitsflowrate durch die Katheter begrenzt.Schlußfolgerung. Wir stellten fest, daß ein an ein Umwandler angeschlossener Katheter mit mindestens 20-G Drücke in der zerebrospinalen Flüssigkeitskammer mit einem hohen Maß an Genauigkeit aufnehmen kann. Die längere Zeit zum Erreichen des Gleichgewichts machte dasU-Rohr-Manometer für den klinischen Gebrauch untauglich.

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Resumen Objetivo. El objetivo de este estudio fue determinar la fidelidad de transmisión de señales de presión a través de catéteres largos y finos (epidurales), insertados en el espacio intratecal lumbar.Métodos. Utilizando un modelo del canal espinal, estudiamos tres catéteres epidurales: Arrow 20-G, Abbott 20-G y Portex 21-G. Determinamos la frecuencia natural y el coeficiente de amortiguación para cada uno de los tres catéteres, correlacionando las presiones estáticas medidas por cada uno de los tres catéteres con la presión real en el espacio intratecal, y comparamos para cada catéter los tiempos de respuesta, tanto conectados a transductores como conectados a manómetros de tubo enU. Resultados. Los tres catéteres presentaron coeficiente de amortiguación alto (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) y frecuencia natural baja (Arrow, 15.23 Hz; Abbott, 12.83 Hz; y Portex, 9.09 Hz). Las características de respuesta dinámica del catéter con mayor diametro interno (Arrow 20-G) fueron adecuadas para reproducir en form confiable la presión pulsátil del líquido céfalo-raquídeo. Catéteres más delgados permitieron pesquisar los cambios de presión media, si bien las oscilaciones resultaron amortiguadas. Las mediciones de presión estática a través de los tres catéteres demostraron buena correlación con la presión real (r=0.99, p<0.001). Al usar un manómetro de tubo enU, los tiempos necesarios para alcanzar equilibrio con una presión de 30 cm H₂O fueron 170, 140 y 130 minutos para los catéteres Portex, Abbott y Arrow, respectivamente. La velocidad de ascenso de presión en el manómetro de tubo enU estuvo limitada por la velocidad de flujo de líquido a través de los catéteres.Conclusiones. Encontramos que catéteres de calibre al menos 20-G, conectados a un transductor, pudieron reproducir la presión del líquido céfalo-raquídeo con un alto grado de fidelidad. El prolongado tiempo requerido para alcanzar equilibrio hace que la manometría con tubo enU sea inapropiada para uso clínico.

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Résumé Objectifs. Le but de cette étude est de déterminer la fidélité des sigaux de pression transmis par de longs cathéters fins introduits dans l'espace intrathécal au niveau lombaire.Méthodes. A l'aide d'un modèle de canal rachidien, nous avons évalué trois cathéters épiduraux: Arrow 20G, Abbott 20G, et Portex 21G. Nous avons déterminé le coeffieient d'amortissement et la fréquence propre des 3 cathéters et nous avons comparé, d'une part, les pressions statiques mesurés par les 3 cathéters avec la pression réelle régnant dans l'espace intrathécal, et, da'autre part, les temps de réponse des 3 cathéters reliés à des transducteurs ou reliés à un manométre de type tube enU. Résultats. Les trois cathéters ont présenté des coefficients d'amortissement élevés (Arrow: 0,75; Abbott: 0,85; Portex: 1,10) et des fréquences propres basses (Arrow: 15,23 Hz; Abbott: 12,83 Hz; Portex: 9,09 Hz). Les caractéristiques en réponse dynamique du cathéter de plus grand diamètre interne (Arrow 20G) ont entrainé une reproduction fiable de la pression pulsatile du liquide céphalo-rachidien. Les cathéters les plus petits ont permis de suivre la pression artérielle moyenne, mais les oscillations étaient amorties. Il existait une bonne corrélation entre les mesures de pression statique avec les 3 cathéters et la pression contrôle (r=0,99, p<0,001). Avec un manomètre type tube enU, les délais nécessaires jusqu'à l'équilibre des pressions lors de l'application d'une pression contrôle de 30cm H₂O ont été respectivement de 170, 140, et 130 minutes pour les cathéters Portex, Abbott, et Arrow. L'augmentation de la pression dans le manomètre type tube enU était limité par le débit de fluide à travers les cathéters.Conclusions. Nous avons trouvé qu'un cathéter de diamètre interne d'au moins 20G connecté à un transducteur pouvait transmettre les pressions avec un haut degré de fidélité. Le durée longue nécessaire pour atteindre l'équilibre rend le manomètre type tube enU inadapté pour l'usage clinique.

     

Peripheral vascular effects on auscultatory blood pressure measurement

Experiments were conducted to examine the accuracy of the conventional auscultatory method of blood pressure measurement. The influence of the physiologic state of the vascular system in the forearm distal to the site of Korotkoff sound recording and its impact on the precision of the measured blood pressure is discussed. The peripheral resistance in the arm distal to the cuff was changed noninvasively by heating and cooling effects and by induction of reactive hyperemia. All interventions were preceded by an investigation of their effect on central blood pressure to distinguish local effects from changes in central blood pressure. These interventions were sufficiently moderate to make their effect on central blood pressure, recorded in the other arm, statistically insignificant (i.e., changes in systolic [p<0.3] and diastolic [p<0.02]). Nevertheless, such alterations were found to modify the amplitude of the Korotkoff sound, which can manifest itself as an apparent change in arterial blood pressure that is readily discerned by the human ear. The increase in diastolic pressure for the cooling experiments was statistically significant (p<0.001). Moreover, both measured systolic (p<0.004) and diastolic (p<0.001) pressure decreases during the reactive hyperemia experiments were statistically significant. The findings demonstrate that alteration in vascular state generates perplexing changes in blood pressure, hence confirming experimental observations by earlier investigators as well as predictions by our model studies.Supported in part by NIH grants no. HL 10,330, HL 22,223, and HL 31,480.     

Oscillometric blood pressure measurement: a simple method in screening for peripheral arterial disease

Blood pressure at the ankle level is a reliable indicator of peripheral arterial disease (PAD) and the ankle brachial index (ABI) is a useful non-invasive screening tool for the early detection of atherosclerosis. In the first part of the study, systolic blood pressures obtained by oscillometry and plethysmography were compared in 80 subjects referred for possible vascular disease. In the second part of the study, 31 general practitioners enrolled 1258 consecutive patients aged more than 60 years. ABI was estimated by oscillometry. Patients with an ABI lower than 0.9 were referred to the local hospital for standardized measurements. In the first part, oscillometry showed a sensitivity of 97% and a specificity of 62% with a positive and negative predictive value of 71% and 96%, respectively. In the second part, significant PAD was found in 111 cases corresponding to a prevalence of 12.2%. In this population, the oscillometry showed a positive predictive value of 47%. The presence of PAD was significantly correlated to exercise related leg pain, a diagnosis of hypertension and smoking, whereas no correlation could be found with a diagnosis of heart disease, stroke, or with the presence of diabetes. The prevalence of PAD was sufficiently high in subjects over the age of 60 years to warrant screening. The ankle brachial index based on measurements with an oscillometric device was shown reliable in the exclusion of PAD, thereby fulfilling an important criterion for the use in screening.     

Deep learning-based automatic blood pressure measurement: evaluation of the effect of deep breathing,talking and arm movement

Abstract

Objectives: It is clinically important to evaluate the performance of a newly developed blood pressure (BP) measurement method under different measurement conditions. This study aims to evaluate the performance of using deep learning-based method to measure BPs and BP change under non-resting conditions.

Materials and methods: Forty healthy subjects were studied. Systolic and diastolic BPs (SBPs and DBPs) were measured under four conditions using deep learning and manual auscultatory method. The agreement between BPs determined by the two methods were analysed under different conditions. The performance of using deep learning-based method to measure BP changes was finally evaluated.

Results: There were no significant BPs differences between two methods under all measurement conditions (all p?>?.1). SBP and DBP measured by deep learning method changed significantly in comparison with the resting condition: decreased by 2.3 and 4.2?mmHg with deeper breathing (both p?<?.05), increased by 3.6 and 6.4?mmHg with talking, and increased by 5.9 and 5.8?mmHg with arm movement (all p?<?.05). There were no significant differences in BP changes measured by two methods (all p?>?.4, except for SBP change with deeper breathing).

Conclusion: This study demonstrated that the deep learning method could achieve accurate BP measurement under both resting and non-resting conditions.

• Key messages

• Accurate and reliable blood pressure measurement is clinically important. We evaluated the performance of our developed deep learning-based blood pressure measurement method under resting and non-resting measurement conditions.

• The deep learning-based method could achieve accurate BP measurement under both resting and non-resting measurement conditions.

     

血液透析患者家庭自测血压与透析日血压的相关性研究

目的 调查家庭自测血压与血液透析中心测量血压的关联度,患者在透析中心测量的血压中,哪一个能更好反映非透析日血压的状态. 方法 有56名血液透析患者参与研究,分别采集患者家庭自测血压、上机前血压及上机后不同时间点血压情况,比较不同时间点血压测量值之间的相关性.结果 上机后1h血压判定为高血压组、正常血压组与家庭自测血压判定为高血压组、正常血压组的符合率最高,分别为81.8％、61.8％.将患者按照家庭自测血压状态分为高血压组和正常血压组后,可见高血压组上机前30min的收缩压、舒张压与家庭自测收缩压、舒张压的差值最小,而正常血压组,上机前30min的收缩压、舒张压与家庭自测收缩压、舒张压的差值最大. 结论 上机后1h血压判定为高血压组、正常血压组与家庭自测血压判定为高血压组、正常血压组的符合率最高,可以通过上机后1h血压状态估计患者透析间期的血压情况.     

Accuracy of oscillometric blood pressure measurement in critically ill neonates with reference to the arterial pressure wave shape

Objective To perform further evaluation of the oscillometric device for neonatal arterial blood pressure (ABP) measurement, using a catheter-manometer system (CMS) for accurate intraarterial measurement. We aimed to describe the influence of the radial artery wave shape on oscillometric ABP determination, as pressure, wave-shape influences the relationships between systolic arterial pressure (SAP),diastolic arterial pressure (DAP) and mean arterial pressure (MAP) in the wave. These relationships are part of the algorithms contributing to the final ABP determination in the oscillometric device.Design Intra-patient comparison of two blood pressure measurement systems.Setting Neonatal intensive care unit.Patients In 51 critically ill newborn infants, ABP was determined oscillometrically in the brachial artery and, simultaneously, invasively in the radial artery using a high-fidelity CMS. Clinical data of the infants were: gestational age: 29 (25–41) weeks; brithweight: 1200 (500–3675) g, postnatal age: 6 (2–46) h.Methods Statistical analysis was performed with the paired Student'st-test. Multiple regression analysis was used to determine the influence of birthweight and height of the blood pressure on the results.Measurements and main results In 51 infants, 255 paired values of SAP, DAP and MAP were recorded. In all recordings we determined the relationship between SAP, DAP and MAP, using the equation.MAP=%(SAP-DAP)+DAP. For SAP, DAP, MAP and , we computed mean differences (bias) and the limits of agreement (precision). Biases for SAP, DAP, MAP and were significantly different from zero (P<0.001) and the limits of agreement for SAP, DAP and MAP were wide: 18.8 mmHg, 17.2 mmHg and 15.2 mmHg respectively The relationship between invasive and noninvasive values is only partly (7–19%) influenced by the height of the blood pressure; low values of SAP, DAP and MAP tend to give overestimated oscillometric values. In the relationship between SAP, DAP and MAP, was found to be 47% invasively (as generally found in the radial artery in newborns) and 34% noninvasively (as generally found in the brachial/radial artery in adults).Conclusions Inaccuracy of the oscillometric device may be partly explained by the incorporation of an inappropriately fixed algorithm for final ABP determination in newborns. Care should be taken when interpreting the oscillometrically derived values in critically ill newborn infants.Abbreviations ABP Arterial blood pressure - SAP Systolic arterial pressure - MAP Mean arterial pressure - DAP Diastolic arterial pressure - PP Pulse pressure - MAP% Level of MAP in the wave in relation to SAP and DAP expressed as MAP% (MAP-DAP)/(SAP-DAP)×100% - CMS Catheter-manometer system - IRDS Idiopathic respiratory distress syndrome     

Comparative effects of cuff size and tightness of fit on accuracy of blood pressure measurements

To determine the effect of snugness of cuff wrap on the accuracy of blood pressure (BP) measurements, we performed two studies on 6 healthy volunteers. In both studies, control values were obtained from the right upper arm with cuffs of appropriate size and snug fit. Study 1 had two phases. In the first, cuffs of appropriate size were wrapped snugly around the upper left arm of seated subjects. The effects of two other degrees of cuff snugness on the measurement of BP were evaluated by placing a filled 250-mL intravenous fluid bag between the cuff and arm over the triceps, measuring BP, then draining the same bag of half its contents and then all of its contents without rewrapping the cuff (loose, very loose fit), each time measuring BP. The second phase of study 1 was identical in procedure, except that the cuffs used on the left arm were one size too small. In study 2, the experimental cuffs were placed just above the right ankle. To alter the signal-to-noise ratio, BP was raised or lowered: the standing position elevated mean BP by an average of 90 mm Hg, and elevation of the legs decreased mean BP by an average of 43 mm Hg. In study 1, we found that appropriately sized cuffs, whether wrapped tightly or loosely, gave correct BP readings. Cuffs snugly wrapped, but too small for the subject, gave high BP readings, on the average by approximately 10 mm Hg. Loose wrapping of small cuffs gave variable results in individual subjects that exaggerated systolic BP from 2 to 80 mm Hg. In study 2, elevating the legs or standing decreased or increased BP consistently. Loose wrapping of appropriately sized cuffs around the ankles of the subjects had no additional significant effect on BP.     

Rapid measurement of blood pressure in the sick neonate

We measured mean arterial blood pressure using a hydrostatic technique in 24 sick neonates who had umbilical artery catheters in place. Values for blood pressure obtained with this technique correlated significantly (r= 0.9844,P<0.01) with measurements obtained with standard strain gauge and electronic monitor. The method is simple, quick, and safe. It is particularly useful when the infant's size or clinical condition precludes the use of the sphygmomanometer or Doppler ultrasound device or in a setting, such as during transport, when standard electronic means of blood pressure measurement are unavailable.Supported in part by MRP HD 11021     

Noninvasive continuous blood pressure measurement during anaesthesia: A clinical evaluation of a method commonly used in measuring devices

The objective of the study was assess the utility during anaesthesia of noninvasive continuous blood pressure measurement techniques which use intermittent oscillometric blood pressure measurement for their calibration. The assessment was performed by comparing noninvasive blood pressure with intra-arterial blood pressure. The noninvasive blood pressure measurement device used for evaluation was the NCAT N-500 which uses tonometry for its continuous measurements. Fifteen patients were studied. In 10 patients the intra-arterial blood pressure curve (IBP) was recorded from the radial artery (radial artery group), and in 5 patients it was recorded from the brachial artery (brachial artery group). In all patients the oscillometrically calibrated tonometric blood pressure (OTBP) was recorded from the other arm. To discriminate between calibration dependent measurement error and tonometric measurement error, the OTBP signal was recalibrated against the IBP signal to get the intra-arterial calibrated tonometric pressure curve (ITBP). OTBP-IBP reflected the overall measurement error, ITBP-IBP the error of the tonometric measurement, and OTBP-ITBP the calibration dependent measurement error. According to criteria formulated in the discussion the accuracy and agreement of the ITBP-IBP measurements were clinical acceptable. Accuracy and agreement of OTBP-IBP and of OTBP-ITBP were not clinical acceptable. Correlation of dynamic behavior was lower for OTBP than for ITBP. A significant effect of site difference between calibration measurements and continuous measurements was not found. It is concluded that the approach of continuous noninvasive blood pressure measurement based on the combination of two different measurement methods, in which the continuous method is calibrated by the oscillometric method, lead to clinical unacceptable accuracy and agreement in the patient group studied.     

农民健康体检中血压测量的质量评估及分析

目的 了解农民健康体检中血压测量的质量.方法 对丽水市辖区4个农民体检点的血压测量质量进行评估及分析.结果 4个体检点由8位血压测量员检测514人血压,均用电子血压计,品牌不同;电子血压计测得血压平均值为(133.21±21.62)/(82.84±12.41)mmHg,经汞柱血压计复测为(126.78±21.09)/(80.15±11.59)mmHg;测血压环境不够理想;血压测量员测血压不够规范.结论 农村健康体检中血压测量质量存在问题,有待改进.