Noninvasive Blood Pressure Monitoring Research Articles

A non-invasive heart rate and blood pressure monitoring system using piezoelectric and photoplethysmographic sensors

In this work, a non-invasive heart rate (HR) and blood pressure (BP) monitoring system using a lead zirconate titanate (PZT) piezoelectric and photoplethysmographic (PPG) sensor has, preliminarily, been investigated. A modified pulse transit time (MPTT) is applied to demodulate HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP) from obtained BP waveforms. In addition, an engineering application software written by LabView programming is, also, developed for dynamic signal monitoring and processing of desired parameters. Consequently, HR and BP measurements on 15 volunteers are performed and validated against a reference digital sphygmomanometer. The results show equivalent HR from both sensors with a mean absolute difference (MAD) of 1.78 beats per minute. Meanwhile, MADs of SBP and DBP measurements are 2.62 and 1.36 mmHg, complying with AAMI-BHS accuracy of “Grade A”, respectively. Therefore, PZT and PPG-based monitoring system could lead to development of accurate, non-invasive, and low-cost HR and BP devices.

Case Series in the Utility of Invasive Blood Pressure Monitoring in Microvascular Decompression.

The utility of arterial lines in microvascular decompression (MVD) is not well described. To examine the safety and costs of arterial lines compared with noninvasive blood pressure (NIBP) monitoring in MVDs. We retrospectively reviewed patients undergoing MVD from 2012 to 2020. Patients were grouped by procedure date from 2012 to 2014 and 2015 to 2020, reflecting our institution's decreasing trend in arterial line placement around 2014 to 2015. Patient features, intraoperative characteristics, and postoperative complications were collected for all cases. Statistical differences were evaluated using chi-squared analyses and t-tests. Eight hundred fifty-eight patients underwent MVDs, with 204 between 2012 and 2014 and 654 between 2015 and 2020. Over time, the frequency of arterial line placement decreased from 64.2% to 30.1%, P < .001. Arterial lines involved 11 additional minutes of preincision time, P < .001. Patients with arterial lines required both increased doses and costs of vasoactive medications intraoperatively. Patients receiving arterial lines demonstrated no significant differences in complications compared with patients with NIBP monitoring. On average, patients with arterial lines incurred $802 increased costs per case compared with NIBP monitoring. NIBP monitoring in MVDs provides neurologically and hemodynamically safe outcomes compared with invasive blood pressure monitoring. For patients without significant cardiopulmonary risk factors, NIBP monitoring may be a cost-effective alternative in MVDs.

Inflationary noninvasive blood pressure monitoring reduces lower-limb pain during measurement

Objective: This study aimed to investigate whether inflationary noninvasive blood-pressure measurement reduces pain during blood-pressure monitoring with the lower limbs compared to the conventional noninvasive measurement method.Methods: Healthy volunteers aged ≥ 18 years were recruited for the study. After seating the participants, a manchette was fitted onto each limb (upper limbs: YP-713T YAWARA CUFF2 13 cm; lower limbs: YP-715T YAWARA CUFF2 for thigh 19 cm, Nihon Kohden Tokyo, Japan). The inflationary and conventional noninvasive blood-pressure measurement devices (PVM-9901 and PVM-9901, Nihon Kohden, Tokyo, Japan) were connected, and the blood pressure was measured simultaneously at two points in the upper and lower limbs. After the measurement, the participants answered a questionnaire regarding the lower-limb pain, and the intensity of pain was evaluated using the visual analog scale.Results: The study included 111 healthy volunteers. The visual analog scale scores of the upper and lower limbs were significantly lower with the inflationary noninvasive blood pressure measurement device than with the conventional noninvasive blood pressure device (upper limbs: 25.6 ± 23.2 vs. 38.8 ± 27.5, p &lt; .001 and lower limbs: 42.2 ± 25.1 vs. 54.2 ± 26.1, p &lt; .01, respectively).Conclusions: We examined the effect of pain reduction on the lower limbs with inflationary noninvasive blood-pressure measurements in healthy volunteers. We conclude that inflationary noninvasive blood pressure measurement may reduce pain in the lower limbs during blood-pressure monitoring compared to a conventional noninvasive blood pressure measurement.

A robust and flexible pulse wave sensory array enabling real-time non-invasive blood pressure monitoring

Chronical cardiovascular decreases such as hypertension requires real-time and continuous monitoring of blood pressures (BPs). Pulse wave that contains critical and ample information on cardiovascular dynamics is a direct vital sign to extract BP and therefore an epidermal wearable device enabling real-time acquisition of pulse waves becomes necessary. In this work, we propose and study a flexible pulse wave sensory array aiming for real-time wearable pulse wave acquisition with robustness. A piezoelectric sensor together with a thin-film transistor-based sensor interface circuit is used to detect multiple pulse waveforms at the location of radial artery, which are input to a convolutional neural network for a deep-learning BP estimation model training. The estimated BPs are assessed by a correlation study with the BPs measured by conventional sphygmomanometers. Our study shows a reasonable accuracy of mean deviation and standard deviation of 2.84 ± 7.53 mmHg for systolic BP and 0.88 ± 7.06 mmHg for diastolic BP.

Low-cost noninvasive continuous blood pressure monitor

Low-cost noninvasive continuous blood pressure monitor

A Flexible, Wearable, and Wireless Biosensor Patch with Internet of Medical Things Applications.

Monitoring the vital signs and physiological responses of the human body in daily activities is particularly useful for the early diagnosis and prevention of cardiovascular diseases. Here, we proposed a wireless and flexible biosensor patch for continuous and longitudinal monitoring of different physiological signals, including body temperature, blood pressure (BP), and electrocardiography. Moreover, these modalities for tracking body movement and GPS locations for emergency rescue have been included in biosensor devices. We optimized the flexible patch design with high mechanical stretchability and compatibility that can provide reliable and long-term attachment to the curved skin surface. Regarding smart healthcare applications, this research presents an Internet of Things-connected healthcare platform consisting of a smartphone application, website service, database server, and mobile gateway. The IoT platform has the potential to reduce the demand for medical resources and enhance the quality of healthcare services. To further address the advances in non-invasive continuous BP monitoring, an optimized deep learning architecture with one-channel electrocardiogram signals is introduced. The performance of the BP estimation model was verified using an independent dataset; this experimental result satisfied the Association for the Advancement of Medical Instrumentation, and the British Hypertension Society standards for BP monitoring devices. The experimental results demonstrated the practical application of the wireless and flexible biosensor patch for continuous physiological signal monitoring with Internet of Medical Things-connected healthcare applications.

CORRELATION OF ARSENIC AND HESPERIDIN ON BLOOD PRESSURE IN WISTAR RAT.

Background: Arsenic causes various health problems including cardiovascular abnormalities through contaminated drinking water and environmental exposure. Arsenic cardiovascular toxicity is the major concern nowadays. Hesperidin, a avonoid, may alter the Arsenic induced toxicity. Objectives: The aim of our study was to nd out the protective role of hesperidin against Arsenic exposure effects on blood pressure in wistar rats. Materials and Methods: Eighteen male wistar rats were procured from Indian Institute Of Toxicology and Research (CSIR-IITR), Lucknow, UP. Rats were divided into three groups equally (n=6). Group-Awere taken as control, Animals of Group B were treated with Sodium Arsenite, while Sodium Arsenite and Hesperidin was given to animals of Group C in desired doses. Blood Pressure was measured with NIBP(Non Invasive Blood Pressure) Monitoring machine before starting of treatment and at the every end of weeks for four successive weeks. Results: In our present study we found that the effect of Arsenite and hesperidin was statistically signicant. Results showed that the systolic blood pressure was raised by treatment with sodium arsenite and the hesperidin was able to reduce the arsenite induced increment of blood pressure in wistar rats. Conclusion: There exist a signicant increase of systolic blood pressure with Sodium Arsenite and Hesperidin protects against rise in systolic blood pressure.

The Relationship between Hypoglycaemic Episodes and Arrhythmias in Type 2 Diabetes Subjects after Acute Myocardial Infarction with ST-Segment Elevation—A Case Series

Background and Aims: Several studies have shown that hypoglycaemia, especially a severe episode is associated with an increased mortality rate in diabetes mellitus subjects with previous cardiovascular disease or acute coronary syndrome. One of the presumed mechanisms is the proarrhythmic effect of hypoglycaemia related to the prolongation of the action potential, or the catecholamine surge that follows an episode. The aim of this case series analysis was to investigate the relationship between hypoglycaemia and glucose variability with arrhythmic events in type 2 diabetes patients who suffered an acute myocardial infarction. Materials and Methods: We selected patients admitted consecutively to the cardiology department of Clinical Emergency Hospital in Bucharest for a period of three months with acute myocardial infarction and previously diagnosed type 2 diabetes. For each patient, a retrospective continuous glucose monitoring system (CGMS) or glucose sensor (Medtronic&#174 Enlite, USA) and a dual electrocardiograph and blood pressure monitor for 24 hours were available. Also, patients had an oscillometric device (Arteriograph&#174 TensioMed Ltd) for 24 hours or non-invasive monitoring of central blood pressure, pulse wave velocity and augmentation index. The data were analysed using Medtech&#174, TensioWin&#174 and Carelink iPro&#174 softwares. We used SPSS&#174 version 20.0 (IBM) for the statistical analysis. The results are presented as median and interquartile range (IQR). Results and Discussion: Ten type 2 diabetes patients (4 males, 6 females) with anterior (4/10) and inferior acute myocardial infarction (6/10) were included. They were treated with insulin (3/10), sulphonylurea (Gliclazide) plus Metformin (4/10), Metformin monotherapy (2/10), or all three (1/10). The patients had a median age of 67.5 (3.25) years with a median disease duration of 8 (7.75) years. The median body mass index was 29.54 (5.65) kg/m2. The median HbA1c was 7.9% (3.15) % and C-peptide 3.3 (2.66) ng/ml. There were no significant differences regarding the number of atrial or ventricular premature beats, ventricular or atrial tachycardia or fibrillation, the duration of QT interval, systolic and diastolic blood pressure, aortic pressure, augmentation index, pulse wave velocity between subjects with hypoglycaemia and those without. There was a negative correlation between QTc and glucose values in patients with hypoglycaemia (Spearman coefficient correlation r = -0.232; p Conclusion: Mild hypoglycaemia in type 2 diabetes patients with systolic dysfunction after ST-elevated myocardial infarction did not increase the number of supraventricular premature beats and QTc duration. We suggest that non-severe hypoglycaemia does not increase the risk of arrhythmias in patients with type 2 diabetes.

Photoplethysmography Fast Upstroke Time Intervals Can Be Useful Features for Cuff-Less Measurement of Blood Pressure Changes in Humans.

Photoplethysmography (PPG) waveform analysis is being increasingly investigated for continuous, non-invasive, and cuff-less blood pressure (BP) measurement. However, the efficacy of this approach and the useful features and models remain largely unclear. The objectives were to develop easy-to-understand models relating PPG waveform features to BP changes (after a cuff calibration) and to determine their value in BP measurement accuracy. The study data comprised finger, toe, and ear PPG waveforms, an ECG waveform, and reference manual cuff BP measurements from 32 human subjects (25% hypertensive) before and after slow breathing, mental arithmetic, cold pressor, and nitroglycerin administration. Stepwise linear regression was employed to create parsimonious models for predicting the intervention-induced BP changes from popular PPG waveform features, pulse arrival time (PAT, time delay between ECG R-wave and PPG foot), and subject demographics. Leave-one-subject-out cross validation was applied to compare the BP change prediction root-mean-squared-errors (RMSEs) of the resulting models to reference models in which PPG waveform features were excluded. Finger b-time (PPG foot to minimum second derivative time interval) and ear "STT" (PPG amplitude divided by maximum derivative), when combined with PAT, reduced the systolic BP change prediction RMSE of reference models by 6-7% (p 0.022). Ear STT together with pulse width reduced the diastolic BP change prediction RMSE of the reference model by 13% (p = 0.003). The two PPG fast upstroke time intervals can offer some added value in cuff-less BP trending. This study offers important information towards achieving non-invasive and passive BP monitoring without a cuff.

Blood Pressure Estimation From Korotkoff Sound Signals Using an End-to-End Deep-Learning-Based Algorithm

While measurement of blood pressure (BP) is now widely carried out by automated non-invasive BP (NIBP) monitoring devices, as they do not require skilled clinicians and do not carry risk of complications, their accuracy is in doubt. A novel end-to-end deep learning-based algorithm was developed in this study that estimates NIBP directly from sequences of Korotkoff sounds (KSs) rather than oscillometric waveforms. First, sequences of segments of KSs were formed using different signal segmentation techniques, i.e., segmentation using sliding window with or without overlap and segmentation using the cardiac period estimation. Each segment within each sequence was then labeled as (i) after-systolic and before-diastolic (AB), or (ii) before-systolic or after-diastolic (BA) such that a binary sequence-to-sequence classification problem was achieved. To deal with the resultant sequence-to-sequence classification problem, an algorithm was developed by combining one-dimensional (1D) convolutional neural networks (CNNs) and recurrent neural networks (RNNs). The segments associated with systolic and diastolic blood pressure (SBP and DBP) are then identified as the segments at which the output target sequence switches from class BA to class AB and later from class AB to class BA. Lastly, the values of SBP and DBP are obtained by mapping the center point of the switching segments to the deflation curve. To evaluate the performance of the proposed NIBP estimation method, we used a database of 350 NIBP samples collected from 155 participants (87 male, age: 23-97 years, arm circumference: 10-35 cm, SBP: 81-104 mmHg, and DBP: 37-104 mmHg), and the achieved estimation errors for SBP and DBP, relative to the reference values, using a 5-fold cross validation approach, were 1.6±3.9 mmHg (mean absolute error ± standard deviation of error) and 2.5±4.0 mmHg, respectively. We finally conclude that the proposed end-to-end deep learning-based NIBP estimation algorithm from sequences of KSs is a novel technique that requires modest preprocessing steps and can measure BP accurately.

Comparison of invasive blood pressure monitoring versus normal non-invasive blood pressure monitoring in ST-elevation myocardial infarction patients with percutaneous coronary intervention

BackgroundHypotension post percutaneous coronary intervention (PCI) causes stent thrombosis and reduced coronary perfusion, which aggravate myocardial ischemia and lead to patient death. Therefore, the accuracy and timeliness of blood pressure monitoring (BPM) are crucial for the nursing of patients post PCI. However, it is still controversial whether invasive blood pressure monitoring (IBPM) or non-invasive blood pressure monitoring (NIBPM) should be used for patients post PCI, and the magnitude of their assistance for patients’ recovery remains unclear. MethodsA randomized controlled trial was performed in this study. 126 ST-segment elevation myocardial infarction (STEMI) patients post PCI were recruited and randomly divided into two groups (NIBPM group n = 63; IBPM group n = 63). ResultsClinical characteristics and physiological outcomes of participants received different BPM methods were collected and analyzed to compare the effects of these two methods on the nursing of PCI patients. Compared to NIBPM group, IBPM assisted to shorten the time of myocardial ischemia, promote coronary reperfusion, reduce the occurrence of cardiovascular disease and other complications, and ultimately reduce the mortality of patients post PCI. ConclusionThe application of IBPM contributed to reduce the occurrence of complications, shorten the time of vascular reperfusion, and guide treatment of clinicians in time.

RETRACTED:Treatment effects and mechanisms of Cu(II) coordination polymer in hypotension after anesthesia

A Cu(II) coordination polymer (CP) (that is, [Cu2(OH)(H2O)2(cbca)·2H2O]n (1)) has been obtained with the reaction between Cu(II) salt and 4′-(1-carboxyethoxy)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3cbca), a semi-rigid tricarboxylic acid ligand under the hydrothermal reaction condition. Prevention activity of the new compound on hypotension after anesthesia surgery was evaluated and the related mechanism was researched at the same time. The noninvasive blood pressure monitor was firstly conducted to measure the blood pressure of the animal after compound treatment. Besides, the real time RT-PCR assay was also used to determine theα receptor relative expression on vascular endothelial cells after compound treatment.

Comparison of Invasive Arterial Blood Pressure Monitoring vs. Non-Invasive Blood Pressure Monitoring in Preterm Infants < 37 Weeks in the Neonatal Intensive Care Unit- A Prospective Observational Study.

Accurate measurement of blood pressure (BP) is extremely important in the management of sick preterm newborns. The primary objective of this study was to compare non-invasive blood pressure measurement (NIBP) with invasive blood pressure measurement (IBP) using peripheral arterial cannulation (PAC) in preterm neonates < 37 weeks in the neonatal intensive care unit. Preterm neonates needing PAC were prospectively enrolled in the study. NIBP measurements were taken in the same limb as that of peripheral arterial line. Initially IBP was recorded followed by NIBP within 1 min using the same monitor. These were called as paired measurements since they are taken within 1 min of each other. Seventy-three preterm infants with 1703 paired measurements were included in the final analysis (median gestational age 32 weeks, IQR 30-34 weeks, median birth weight 1540 g, IQR 1160-2100 g). In preterm infants not receiving vasoactive agents (n = 51, 1428 paired measurements, Bland-Altman analysis for agreement between invasive mean blood pressure (MBP) and non-invasive mean BP revealed a bias of -2.9123 mmHg (SD 7.8074). The 95% limits of agreement were from -18.2157 to 12.3893 mmHg. In preterm infants with hypotension, we detected a bias of -3.9176 mmHg (SD 5.1135) between invasive MBP and non-invasive MBP. The 95% limits of agreement were from -13.9401 to 6.1048 mmHg. In normotensive preterm infants receiving vasoactive agents, we detected a bias of -0.7629 mmHg (SD 8.0539) between invasive MBP and non-invasive MBP. The 95% limits of agreement were from -16.5485 to 15.02274 mmHg. There is poor level of agreement between IBP and NIBP measurements in sick preterm neonates, leading to overestimation or underestimation of blood pressure. The bias was less for mean BP measurements as compared with systolic BP measurements and also for normotensive neonates as compared with hypotensive neonates. Hence, NIBP may be used as a screening method in haemodynamically stable preterm infants, but infants who are haemodynamically unstable and need to be commenced on vasoactive agents should have IBP monitoring.

Recurrent Neural Network Models for Blood Pressure Monitoring Using PPG Morphological Features.

Continuous non-invasive Blood Pressure (BP) monitoring is vital for the early detection and control of hypertension. However, this is yet not possible as all current non-invasive BP devices are cuff-based devices and hence precluding continuous monitoring. Several methods have been proposed to overcome this challenge, one of which utilises the Photoplethysmograph (PPG) signal in an effort to predict reliable BP values from this signal using various computational approaches. Although, good performance has been reported in the literature, it was mainly achieved on a small inadequate sample size using conventional models that are unable to account for the temporal variations in the input vector. To address these limitations, this paper proposes cuff-less and continuous blood pressure estimation using Long Short-term Memory (LSTM) and Gated Recurrent Units (GRU). The models were evaluated on 942 patients acquired from the Multiparameter Intelligent Monitoring in Intensive Care (MIMIC II) dataset. The proposed models produced superior results in comparison with conventional artificial neural network. In particular, the best performance was achieved by the GRU, with mean absolute error and standard deviation of 5.77 ± 8.52 mmHg and 3.33±5.02 mmHg for systolic (SBP) and diastolic blood pressure (DBP), respectively. Furthermore, the results comply with the international standards for cuff-less blood pressure estimation.

Effects of blood withdrawal on cardiac, hemodynamic, and pulmonary responses to a moderate acute workload in healthy middle-aged and older females

ObjectivesTo investigate the effects of blood withdrawal on cardiac, hemodynamic, and pulmonary responses to submaximal exercise in females. Design and methods30 healthy females (63.8 ± 8.3 years) were recruited for this experimental study. Transthoracic echocardiography, non-invasive blood pressure monitoring, and oxygen uptake were assessed during a fixed submaximal workload (100 W) prior to (day 1) and immediately after (day 2) a 10% reduction of blood volume. Main measurements included left ventricular end-diastolic volume, stroke volume, cardiac output, mean arterial pressure, systolic blood pressure, diastolic blood pressure, and oxygen uptake. Blood volume was determined via carbon monoxide rebreathing. ResultsParticipant's blood volume ranged from 3.8 to 6.6 L. Following 10% reduction in blood volume (0.5 ± 0.1 L), left ventricular end-diastolic volume (p ≤ 0.030) and stroke volume (p < 0.019) were reduced during submaximal exercise while cardiac output was unchanged (p = 0.139) due to increased heart rate (p < 0.026). Hemodynamic variables including mean arterial pressure (p < 0.015), systolic blood pressure (p < 0.005), and diastolic blood pressure (p < 0.038) were reduced while oxygen uptake was unaltered (p = 0.250). ConclusionsBlood withdrawal results in marked reductions in cardiac filling with compensatory chronotropic responses that preserve cardiac output at a moderate submaximal workload in healthy females. Thus, blood volume determines the relative exercise intensity, as typically determined by heart rate, of submaximal efforts in this population.

A Review of Current Literature of Interest to the Office-Based Anesthesiologist.

A Review of Current Literature of Interest to the Office-Based Anesthesiologist.

The systolic to diastolic pressure ratio in non-dipping essential hypertension patients

Nocturnal blood-pressure (BP) decline or dipping is a physiological response in healthy BP-regulation; the lack of this adaptation is frequently observed in patients with essential hypertension (EH) [Chesebro,2020]. Involvement of autonomic dysregulation in EH may result in adrenergic overdrive [Mancia and Grassi,2014; Carthy, 2014]. Heart morphology [Henein, 2011] and systolic to diastolic pressure ratio (SDPR) were previously related to the harmony of the so-called golden ratio (GR = 1.618) [Yetkin, 2015]. We aimed here to identify patterns of circadian dysfunction in newly diagnosed patients with EH compared to individuals with normotensive individuals (NIs) by monitoring them with a non-invasive ambulatory blood pressure monitoring (ABPM) system and evaluating their SDPR.

280 Arterial Line versus Noninvasive Blood Pressure Monitoring in Hypertensive Emergencies

Blood pressure (BP) monitoring is important for managing patients with hypertensive emergencies. Management of such conditions often involves relatively narrow and specific blood pressure windows. While invasive arterial blood pressure (IABP) monitoring is considered the gold standard method of BP measurement, its usefulness is unclear. Although previous studies demonstrated differences between IABP and NIBP values, few had assessed whether these differences would affect clinical management. Our study aimed to determine whether the difference between NIBP and IABP would change BP management in patients with hypertensive emergencies. This was a prospective observational study of adult patients with any hypertensive emergency admitted to the Critical Care Resuscitation Unit (CCRU) at a quaternary academic center from January 2019—April 2021. We included consecutive patients with diagnoses of ischemic stroke, acute aortic disease, spontaneous intracranial hemorrhage (sICH), etc, and who required arterial monitoring. We excluded patients who had hypertensive diagnoses but required vasopressors due to overtreatment of anti-hypertensive medications or those who had arterial catheters prior to arrival. All arterial catheters were inserted upon patients’ arrival per CCRU clinical policy. Patients who had IABP and NIBP in the same extremity and four consecutive measurements of each modality following arterial catheter placement were eligible. Before arterial catheter placement, we recorded in real time clinicians’ decisions to manage patients’ systolic BP (SBP) according to the NIBP values and current guidelines, for example maintaining SBP ≤160 mmHg for patients with sICH. After the arterial catheter was placed, we again recorded in real time clinicians’ management of patients’ arterial SBP. We defined change in clinical management as any difference in blood pressure management (eg, adding a new antihypertensive agent, increasing or decreasing dose). We used Classification and Regression Tree (CART) analysis to identify sensitive and specific clinical predictors of management differences. A total of 183 patients were identified and analyzed, 71 (39%) female. Mean age was 63 years (standard deviation [SD] 14), mean body mass index (BMI) was 29 (6). Mean difference between IABP and NIBP and was 11 mmHg (95% CI 5-17). One hundred and seventeen patients (64%) had difference >10 mmHg between the two modalities, while 70 (38%) had a difference >20 mmHg. Seventy-nine patients (43%) had a change in management after arterial catheters were inserted. The most important factors in predicting management change included mean SBP >148 mmHg. Subsequent important factors were BMI >21, difference in BP value [IABP – NIBP] >6 mmHg, and diagnoses of ruptured abdominal aortic aneurysm, ischemic stroke + alteplase, any aortic dissection. Arterial BP monitoring identified a change in clinical management in almost half of patients with hypertensive emergencies. Clinicians should consider using arterial BP monitoring more frequently in the management of hypertensive emergencies, especially when strict BP goals are warranted.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Continuous Noninvasive Blood Pressure Monitoring of Beat-By-Beat Blood Pressure and Heart Rate Using Caretaker Compared With Invasive Arterial Catheter in the Intensive Care Unit

To examine the accuracy of noninvasively-derived peripheral arterial blood pressure (BP) by the Caretaker device (CT) against invasively measured arterial BP and the fidelity of heart rate variability by CT compared with electrocardiogram (ECG)-derived data. Prospective cohort study. Adult surgical and trauma patients admitted to the intensive care unit. Academic tertiary care medical center. In a prospective manner, beat-by-beat BP by CT was recorded simultaneously with invasive arterial BP measured in patients in the intensive care unit. Invasive arterial BPs were compared with those obtained by the CT system. All comparisons among the CT data, arterial catheter data, and ECG data were postprocessed. From 37 enrolled patients, 34 were included with satisfactory data that overlapped between arterial catheter and CT. A total of 87,757 comparative data points were obtained for the 40-minute time window comparisons of the 34 patients, spanning approximately 22.5 hours in total. Systolic BP and diastolic BP correlations (Pearson coefficient), as well as the mean difference (standard deviation), were 0.92 and -0.36 (7.57) mmHg and 0.83 and -2.11 (6.00) mmHg, respectively. The overall interbeat correlation was 0.99, with the mean difference between interbeats obtained with the arterial BP and the CT of -0.056 ms (6.0). This study validated the noninvasive tracking of BP using the CT device, and the pulse decomposition analysis approach is possible within the guidelines of the standard.

Performance of the Hypotension Prediction Index With Noninvasive Arterial Pressure Waveforms in Awake Cesarean Delivery Patients Under Spinal Anesthesia.

Arterial hypotension is common after spinal anesthesia (SA) for cesarean delivery (CD), and to date, there is no definitive method to predict it. The hypotension prediction index (HPI) is an algorithm that uses the arterial waveform to predict early phases of intraoperative hypotension. The aims of this study were to assess the diagnostic ability of HPI working with arterial waveforms detected by ClearSight system in predicting impending hypotension in awake patients, and the agreement of pressure values recorded by ClearSight with conventional noninvasive blood pressure (NIBP) monitoring in patients undergoing CD under SA. In this retrospective analysis of pregnant patients scheduled for elective CD under SA, continuous hemodynamic data measured with the ClearSight monitor until delivery were downloaded from an Edwards Lifesciences HemoSphere platform and analyzed. Receiver operating characteristic (ROC) curves were constructed to evaluate the performance of HPI algorithm working on the ClearSight pressure waveform in predicting hypotensive events, defined as mean arterial pressure (MAP) <65 mm Hg for >1 minute. The sensitivity, specificity, positive predictive value, and negative predictive value were computed at the optimal cutpoint, selected as the value that minimizes the difference between sensitivity and specificity. ClearSight MAP values were compared to NIBP MAP values by linear regression and Bland-Altman analysis corrected for repeated measurements. Fifty patients undergoing CD were included in the analysis. Hypotension occurred in 23 patients (48%). Among patients experiencing hypotension, the HPI disclosed 71 alerts. The HPI predicted hypotensive events with a sensitivity of 83% (95% confidence interval [CI], 69-97) and specificity of 83% (95% CI, 70-95) at 3 minutes before the event (area under the curve [AUC] 0.913 [95% CI, 0.837-0.99]); with a sensitivity of 97% (95% CI, 92-100) and specificity of 97% (95% CI, 92-100) at 2 minutes before the event (AUC 0.995 [95% CI, 0.979-1.0]); and with a sensitivity of 100% (95% CI, 100-100) and specificity 100% (95% CI, 100-100) 1 minute before the event (AUC 1.0 [95% CI, 1.0-1.0]). A total of 2280 paired NIBP MAP and ClearSight MAP values were assessed. The mean of the differences between the ClearSight and NIBP assessed using Bland-Altman analysis (±standard deviation [SD]; 95% limits of agreement with respective 95% CI) was -0.97 mm Hg (±4.8; -10.5 [-10.8 to -10.1] to 8.5 [8.1-8.8]). HPI provides an accurate real time and continuous prediction of impending intraoperative hypotension before its occurrence in awake patients under SA. We found acceptable agreement between ClearSight MAP and NIBP MAP.