Continuous Non-invasive Arterial Pressure Monitoring Research Articles

Post-anesthesia care unit hypotension in low-risk patients recovering from non-cardiac surgery: a prospective observational study.

Intraoperative hypotension is common and associated with organ injury. Hypotension can not only occur during surgery, but also thereafter. After surgery, most patients are treated in post-anesthesia care units (PACU). The incidence of PACU hypotension is largely unknown - presumably in part because arterial pressure is usually monitored intermittently in PACU patients. We therefore aimed to evaluate the incidence, duration, and severity of PACU hypotension in low-risk patients recovering from non-cardiac surgery. In this observational study, we performed blinded continuous non-invasive arterial pressure monitoring with finger-cuffs (ClearSight system; Edwards Lifesciences, Irvine,CA, USA) in 100 patients recovering from non-cardiac surgery in the PACU. We defined PACU hypotension as a mean arterial pressure (MAP) < 65 mmHg. Patients had continuous finger-cuff monitoring for a median (25th percentile, 75th percentile) of 64 (44 to 91) minutes. Only three patients (3%) had PACU hypotension for at least one consecutive minute. These three patients had 4, 4, and 2 cumulative minutes of PACU hypotension; areas under a MAP of 65 mmHg of 17, 9, and 9 mmHg x minute; and time-weighted averages MAP less than 65 mmHg of 0.5, 0.3, and 0.2 mmHg. The median volume of crystalloid fluid patients were given during PACU treatment was 200 (100 to 400) ml. None was given colloids or a vasopressor during PACU treatment. In low-risk patients recovering from non-cardiac surgery, the incidence of PACU hypotension was very low and the few episodes of PACU hypotension were short and of modest severity.

Continuous non-invasive arterial blood pressure monitoring with photoplethysmography via SE-MSResUNet network

ObjectiveArterial blood pressure (ABP) waveforms include physiological parameters closely related to BP values, while only a few studies predict BP values through the monitoring ABP waveforms. Current ABP waveforms monitoring methods are limited by its high computing cost and information redundancy of multi-channel input signals. The aim of our work is to propose a new end-to-end method for monitoring the ABP waveforms using single-channel photoplethysmography (PPG) signals by constructing a lightweight Multi-Scale Residual U-Net fused with Squeeze-and-Excitation module (SE-MSResUNet) model. MethodsFirstly, the PPG and ABP signals are preprocessed with denoising, segmentation, and eliminating phase difference. Subsequently, the SE-MSResUNet model is constructed and trained using training data to achieve the mapping relationship between PPG and ABP signals. Then, the BP values are extracted from the monitored ABP waveforms. Finally, the performance of the SE-MSResUNet in ABP waveform monitoring and BP estimation is investigated. ResultsThe ABP waveforms monitored by our proposed SE-MSResUNet network with PPG signals only are highly consistent with the reference ABP waveforms. The MAE ± SD of estimated diastolic blood pressure (DBP), mean arterial pressure (MAP) and systolic blood pressure (SBP) compared with reference values are 2.16 ± 3.75, 2.29 ± 3.72, and 3.88 ± 6.17 mmHg, respectively. The proposed method meets the Association for the Advancement of Medical Instrumentation (AAMI) standard and reach A level of the British Hypertension Society (BHS) standard. ConclusionsOur proposed method outperforms current state-of-the-art methods for non-invasive blood pressure monitoring from PPG signals. The algorithm provides a potential possibility for continuous non-invasive blood pressure monitoring through portable wearable devices.

Agreement of continuous non-invasive arterial blood pressure monitoring (CNAP) and pulmonary artery catheter thermodilution method in estimating the hemodynamic parameters of post CABG patients

Abstract Background The use of hemodynamic parameters in monitoring patients after coronary artery bypass surgery is an essential element of clinical practice. It helps intensivist and physicians to properly manage patients after surgery where hemodynamic parameters are usually dynamic and complicated. Pulmonary artery guided thermodilution (PACT) has been the gold standard in assessing the adequacy of cardiac output, however, its invasive nature is also associated with more complex procedures and the risk of complications, including infections. With the emergence of new non-invasive hemodynamic monitoring devices such as the CNAP (continuous non-invasive arterial pressure), alternative methods for hemodynamic monitoring is now possible. Compared to invasive methods, it is easier to use with an error-free application, safer, less risk of infection and more cost effective. Purpose To determine the agreement of Continuous non-invasive arterial pressure (CNAP) and pulmonary artery guided thermodilution in monitoring the hemodynamic parameters of patients who underwent coronary artery bypass graft surgery. Methods This is a cross-sectional study conducted at the cardiovascular surgical intensive care unit and included 63 patients with Coronary artery disease who underwent elective coronary artery bypass graft surgery. Cardiac output, Cardiac Index, Stroke volume and Systemic vascular resistance were simultaneously obtained using both the CNAP and PACT. Three consecutive sets of measurements were recorded for each patient with a 3 hour interval; during arrival at the ICU, 3 hours post op, and 6 hours post op. Results The mean difference between PACT-CO and CNAP-CO was -0.81 L/min (SD -1.18 to -0.44) with a 95% limits of agreement of -3.74 to 2.11 L/min on the 0 hour, -0.81L/min (SD -1.22 to -0.41) with a 95% limits of agreement of -1.98 to 1.18 L/min on the 3rd hour, and -0.77L/min (SD -1.08 to -0.46) with a 95% limits of agreement of -3.22 to 1.68 L/min on the 6th hour post op. The results showed a significant difference between the PACT and CNAP. However, a positive correlation was noted between PACT-CO and CNAP-CO, the correlation coefficient on the 0, 3rd and 6th hour were 0.5384, 0.5158, and 0.6265 respectively. Conclusion CNAP derived hemodynamic parameters had a high mean difference compared to the PACT and there was no agreement between the two methods. However, it was able to have a positive correlation with the PACT, making it possible for the CNAP to track the hemodynamic changes during the post operative course.

Clinical Validation of Wearable Piezoelectric Blood Pressure Sensor for Continuous Health Monitoring.

Wearable blood pressure sensors have recently attracted attention as healthcare devices for continuous non-invasive arterial pressure (CNAP) monitoring. However, the accuracy of wearable blood pressure (BP) monitoring devices has been controversial due to the low signal quality of sensors, the absence of an accurate transfer function to convert the sensor signals into BP values, and the lack of clinical validation regarding measurement precision. Here, we report a wearable piezoelectric blood pressure sensor (WPBPS), which achieved a high normalized sensitivity (0.062 kPa-1 ), fast response time (23ms) for CNAP monitoring. The transfer function of a linear regression model was designed, offering a simple solution to convert the flexible piezoelectric sensor signals into BP values. In order to verify the measurement accuracy of WPBPS, clinical trials were performed on 35 subjects aged from 20s to 80s after screening. The mean difference between the WPBPS and a commercial sphygmomanometer of 175 BP data pairs was -0.89 ± 6.19mmHg and -0.32 ± 5.28mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. By building a WPBPS-embedded wristwatch, we demonstrated the potentially promising use of a convenient, portable continuous BP monitoring system for cardiovascular disease diagnosis in this study. This article is protected by copyright. All rights reserved.

PO-01-208 A COMPUTATIONAL MODEL TO TRACK CHANGES IN LEFT VENTRICULAR END-DIASTOLIC PRESSURE DURING ATRIAL FIBRILLATION

Heart failure and Atrial Fibrillation (AF) commonly occur concomitantly, resulting in significant morbidity and mortality. Thus, monitoring of heart failure status is essential in directing medical therapy in these patients. Left ventricular (LV) filling pressures are one of the most important parameters in assessing worsened or acutely decompensated left heart failure, however current LV pressure monitoring strategies include invasive devices and catheterization. Our study aims to develop a computational model of heart failure in AF and demonstrate that beat-to-beat variations in RR intervals during AF can be exploited to predict changes in LV filling pressure. We used a modified Research CardioVascular SIMulator (RCVSIM) human cardiovascular model to simulate an intact circulatory system in patients with AF over 300 seconds. To simulate beat-by-beat variation of rhythm in AF, the length of each RR-interval was drawn randomly from a Mixed Gaussian Distribution. We modelled worsening HF by changing LV end-systolic compliance in the simulator, using compliances ranging from 1 to 3.5 mL/mmHg, with interval increases in compliance of 0.1 mL/mmHg. Stroke volumes, RR-intervals, and LV end-diastolic pressures are recorded for each simulation. This was repeated for mean heart rates from 60 to 110 beats per minute. Stroke volumes were found to have a strong linear correlation with the previous beat’s RR-interval for all mean heart rates tested (Spearman rho = 0.9-0.97). In Figure 1 below, we show the slope of the RR-interval versus stroke volume (SV/RR-interval) plotted against average LV end-diastolic pressure for all LV systolic compliances noted above and a mean heart rate of 84 beats per minute. A cubic function fit to this plot shows excellent goodness-of-fit with the simulated data with a coefficient of determination (R2) of 0.99. This relationship remained consistent for all mean heart rates tested, and all cubic fits had R2 greater than 0.98. Our study provides a highly accurate model for estimating LV end-diastolic pressures over a broad range of LV systolic heart failure in simulated AF patients using only stroke volume and RR-intervals. Further work using photoplethysmography or continuous non-invasive arterial pressure (CNAP) monitoring could potentially be used to obtain these measures non-invasively, thus leading to a non-invasive method for tracking heart failure in patients with AF.

Fluid resuscitation with guidance of pulse pressure variability measured by continuous non-invasive arterial pressure monitor in postoperative hypovolemic patients: a prospective randomized controlled trial

Fluid resuscitation with guidance of pulse pressure variability measured by continuous non-invasive arterial pressure monitor in postoperative hypovolemic patients: a prospective randomized controlled trial

Comparison of restrictive fluid therapy with goal-directed fluid therapy for postoperative delirium in patients undergoing spine surgery: a randomized controlled trial

BackgroundPostoperative delirium (POD) is a common phenomenon after spinal surgery. Intraoperative fluid management may affect POD. The aim of this study was to compare the effects of restrictive fluid therapy (RF) with those of goal-directed fluid therapy (GDT) on POD.MethodsA total of 195 patients aged ≥ 50 years who underwent spinal surgery were randomly divided into two groups: the RF group and the GDT group. In group RF, a bolus of lactated Ringer’s solution was administered at a dose of 5 mL·kg-1 before the induction of anesthesia, followed by a dose of 5 mL·kg-1·h-1 until the end of surgery. For patients in the GDT group, in addition to the initial administration of lactated Ringer’s solution at 5 mL·kg-1, the subsequent fluid therapy was adjusted by using a continuous noninvasive arterial pressure (CNAP) monitoring system to maintain pulse pressure variation (PPV) ≤ 14%. The primary endpoint was the incidence of POD, assessed once daily with the Confusion Assessment Method-Chinese Reversion (CAM-CR) scale at 1–3 days postoperatively. The secondary endpoints were intraoperative fluid infusion volume, urine volume, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), regional cerebral oxygen saturation (rSO2) value, lactic acid value, and visual analog scale (VAS) pain score at 1–3 days after surgery. Moreover, postoperative complications and the length of hospital stay were recorded.ResultsThe incidence of POD was lower in the GDT group than in the RF group (12.4% vs 4.1%; P = 0.035) in the first 3 days after spine surgery. Compared to group RF, group GDT exhibited a significantly increased volume of intraoperative lactated Ringer’s solution [1500 (interquartile range: 1128 to 1775) mL vs 1000 (interquartile range: 765 to 1300) mL, P < 0.001] and urine volume [398 (interquartile range: 288 to 600) mL vs 300 (interquartile range: 200 to 530) mL, P = 0.012]. Intraoperative MAP, CI and rSO2 values were higher in the GDT group than in the RF group (P < 0.05). Moreover, the length of hospital stay [17.0 (14 to 20) days versus 14.5 (13 to 17.0) days, P = 0.001] was shorter in the GDT group than in the RF group.ConclusionsGDT reduced the incidence of POD in middle- and old-aged patients undergoing spinal surgery possibly by stabilizing perioperative hemodynamic and improving the supply and demand of oxygen.Trial registrationChiCTR2000032603; Registered on May 3, 2020.

Implications of Continuous Noninvasive Finger Cuff Arterial Pressure Device Use during Cesarean Delivery for Goal-Directed Fluid Therapy Preload Optimization: A Randomized Controlled Trial.

Background Although fixed-volume conventional fluid preloading protocol fails to attenuate postspinal hypotension during cesarean delivery, the effect of goal-directed fluid therapy (GDFT) remains less explored. Continuous noninvasive finger cuff arterial pressure monitoring using devices such as the ClearSight System can provide the noninvasive stroke volume value, enabling clinicians to perform GDFT before spinal anesthesia; however, the efficacy of GDFT requires further elucidation. Method In total, 71 consecutive full-term pregnant women were randomly divided into a control group (n = 34) and a GDFT group (n = 37). Before spinal anesthesia, the control group received a fixed dose (1000 mL) of crystalloid fluid, but the GDFT group received repeated 3 mL/kg body weight of crystalloid fluid challenges within 3 minutes with a 1-minute interval between each fluid challenge based on the stroke volume incremental changes obtained using the ClearSight System (targeting a stroke volume increase of ≥5% after a fluid challenge). The primary outcome was the incidence of postspinal hypotension. The secondary outcomes were total fluid volume, vasopressor dosage, hemodynamic parameter changes, maternal adverse effects, and neonatal profiles. Result Women in the GDFT group received more fluid than did those in the control group (1132 ± 108 vs. 1247 ± 202 mL; p = 0.0044), but the incidence of postspinal hypotension (79.4% vs. 73.0%,; p = 0.5864) and norepinephrine dose (12.5 ± 10.6 vs. 15.1 ± 12.8 mcg, respectively; p = 0.3512) was comparable between the two groups. Fewer women in the GDFT group experienced nausea (61.76% vs. 35.14%; p = 0.0332). Neonatal outcomes (Apgar score and umbilical blood analysis) were comparable and typical in both groups. Conclusion ClearSight-guided GDFT did not ameliorate postspinal hypotension but may reduce nausea. This trial is registered with NCT03013140.

Continuous Noninvasive Arterial Pressure Monitoring for Transcatheter Aortic Valve Replacement

The objective of the present study, which was conducted in patients undergoing transcatheter aortic valve replacement, was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA) with invasive radial artery pressure used as the reference method. The authors hypothesized that the ClearSight device is an accurate, precise, safe, and efficient method for arterial blood pressure measurement comparable with an invasive radial arterial line. The study included the retrospective review of 20 consecutive patients scheduled for elective transcatheter aortic valve replacement with the SAPIEN 3 transcatheter heart valve (Edwards Lifesciences) at a single tertiary academic hospital, who underwent monitoring with both the ClearSight device and an invasive radial arterial pressure line. The patients underwent transcatheter aortic valve replacement from October to December 2019. Single tertiary academic medical center. The study comprised 20 patients, with 2,243 unique blood pressure data points. None. A statistically significant correlation between the invasive radial arterial pressure line and the ClearSight device was observed for systolic blood pressure (correlation coefficient 0.86; p < 0.001), diastolic blood pressure (correlation coefficient 0.56; p < 0.001), and mean arterial pressure (correlation coefficient 0.78; p < 0.001). Bland-Altman analysis was used to assess the agreement of systolic blood pressure, diastolic blood pressure, and mean arterial pressure between the two methods. Results for systolic blood pressure between the arterial line and ClearSight device were as follows: bias = 9.8 ± 10.1, percentage bias = 7.6%, and mean error = 15.8%. Results for diastolic blood pressure between the arterial line and ClearSight device were as follows: bias = -5.9 ± 7.8, percentage bias = 10.7%, and mean error = 28.4%. Results for mean arterial pressure between the arterial line and ClearSight device were as follows: bias = 0.3 ± 7.4, percentage bias = 0.4%, and mean error = 18.3%. The concordance rates of systolic blood pressure, diastolic blood pressure, and mean arterial pressure were 100%, 95.1%, and 98.8%, respectively. The accuracy, agreement, and precision of the ClearSight device were convincing for mean arterial pressure, systolic blood pressure, and diastolic blood pressure for patients with severe aortic stenosis undergoing elective transcatheter aortic valve replacement.

Detection of hypotension during spinal anesthesia for caesarean section with continuous non-invasive arterial pressure monitoring and intermittent oscillometric blood pressure monitoring in patients treated with ephedrine or phenylephrine

Introduction/Objective. Despite frequent side effects such as hypotension, spinal anesthesia (SA) is still one of the best anesthetic methods for elective cesarean section (CS). Intermittent, oscillometric, noninvasive blood pressure monitoring (NIBP) frequently leads to missed hypotensive episodes. The objective was to compare continuous non-invasive arterial pressure (CNAP) monitoring with NIBP in the terms of efficiency to detect hypotension. Methods. In this study, we compared CNAP and NIBP monitoring for hypotension detection in 76 patients divided into two groups of 38 patients treated with ephedrine (E) or phenylephrine (P), during threeminute intervals, starting from SA, by the end of the surgery. Results. In E group, significantly lower mean systolic blood pressure (SBP) values with CNAP compared with NIBP (p = 0.008) was detected. By monitoring CNAP, we detected 31 (81.6%) hypotensive patients in E group and significantly lower number, 20 (52.6%), with NIBP (p = 0.001), while in P group CNAP detected 34 patients (89.5%) and NIBP only 18 (47.3%), p = 0.001. By monitoring CNAP, we detected significantly higher number of hypotensive intervals in E and P groups (p &lt; 0.001). Umbilical vein pH was lower within hypotensive compared with normotensive patients in E and P groups, with CNAP and NIBP, respectively (p &lt; 0.001, p = 0.027 in E, and p = 0.009, p &lt; 0.001, in P group). Conclusion. CNAP is more efficient in hypotension detection for CS during SA, which allows faster treatment of hypotension, thus improving fetal and maternal outcome.

Clinical experience of continuous intraoperative non-invasive arterial pressure (CNAP) monitoring in children

Clinical experience of continuous intraoperative non-invasive arterial pressure (CNAP) monitoring in children

Continuous Non-Invasive Arterial Pressure Monitoring (ClearSight System) and Ankle Blood Pressure Measurements as Alternatives to Conventional Arm Blood Pressure.

Measuring blood pressure (BP) via a pneumatic cuff placed around the arm has long been the standard method. However, in clinical situations where BP monitoring at the arm is difficult, the ankle is frequently used instead. We compared continuous non-invasive blood pressure (CNBP) measurements obtained at the finger, ankle BP and arm BP in patients undergoing breast cancer surgery. Arm BP, ankle BP (both obtained with a conventional pneumatic cuff) and CNBP measurements were obtained every 2.5 min during surgery. Correlation and Bland–Altman analyses were performed and differences among measurements were analyzed using a linear mixed model. A total of 245 sets of BP measurements were obtained from 10 patients. All systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) measurements of ankle BP and CNBP were positively correlated with the arm BP measurements (Spearman rho 0.688–0.836, p < 0.001 for each correlation). The difference between CNBP and arm SBP was significantly smaller (least squares mean (95% confidence interval): −6.03 (−11.40, −0.67)) compared to that between ankle and arm SBP (least squares mean (95% CI): −15.32 (−20.69, −9.96), p = 0.019). However, this significant difference was not observed in DBP and MBP (−1.23 vs. 1.75, p = 0.190 and −3.85 vs. −2.63, p = 0.604, respectively). Ankle SBP measurements showed larger differences from arm SBP measurements than did CNBP SBP measurements in patients undergoing breast cancer surgery. CNBP could serve as a useful alternative to ankle BP when standard arm BP measurements cannot be obtained.

The influence of labor epidural analgesia on maternal, uteroplacental and fetoplacental hemodynamics in normotensive parturients: a prospective observational study

BackgroundEpidural analgesia provides sufficient analgesia during labor but can cause hypotension despite various prophylactic measures. We studied its effects on pre-placental, fetoplacental, and fetal hemodynamics using Doppler ultrasound. The primary endpoint was the pulsatility index of the umbilical artery at 30 min after establishing epidural analgesia. Secondary endpoints included maternal blood pressures and neonatal outcome data. MethodsWe included healthy parturients at a cervical dilation ≥2 cm, with or without a request for epidural analgesia (n=32 per group). Ultrasound studies of the uterine arteries, umbilical artery and fetal middle cerebral artery were performed before insertion of the epidural catheter, and 30, 60 and 90 min after; the same time-points were assessed in the non-epidural control group. Maternal blood pressure was measured by a continuous non-invasive arterial pressure monitor. ResultsUltrasound studies detected no significant differences in pulsatility indices over time in any blood vessel. In contrast to the control group, maternal blood pressures were significantly lower for all measures after the onset of analgesia compared with baseline values (mean systolic pressure decreased from 132.7 ± 15.9 mmHg to 123.1 ± 14.4 mmHg at 30 min, P=0.003). The mean pH value of the umbilical arterial blood was 7.29 (±0.06) in the epidural group versus 7.31 (±0.08) in the control group (P=0.33). The median Apgar score at 5 min was 10 in both groups. ConclusionsPre-placental, fetoplacental and fetal hemodynamics remained stable despite a statistically significant decrease in maternal blood pressure in laboring parturients receiving epidural analgesia.

Postoperative continuous non-invasive cardiac output monitoring on the ward: a feasibility study

Postoperative hypotension is common (occurring in one third of patients) and is associated with worse clinical outcomes. The LiDCO CNAP (continuous non-invasive arterial pressure) device measures haemodynamics but has not been widely adopted in ward environments. Improved early detection of hypotension by CNAP might guide interventions to improve clinical outcomes. We aimed to find the proportion of patients who tolerated LiDCO CNAP for 12 h postoperatively, to unmask episodes of hypotension detected by continuous monitoring and to characterise the haemodynamic profile at the time of hypotension. In this feasibility study, patients undergoing major elective surgery were continuously postoperatively monitored using CNAP. Haemodynamic data gathered from CNAP, including nSVRI (nominal systemic vascular resistance index), nSVI (nominal stroke volume index), SVV (stroke volume variation) and blood pressure, were analysed using Microsoft Excel and GraphPad Prism 8. 104 patients (age (mean ± sd): 68 ± 14, male (56%)) had CNAP sited postoperatively. 39% tolerated the CNAP device for at least 12 h. Within the 104 patients a mean of 81.2 min of hypotension detected by CNAP was not detected by usual care. The proportion of low/normal/high nSVI was 71%, 27% and 2%, nSVRI was 43%, 17% and 40%, respectively. CNAP monitoring was not tolerated for 12 h in the majority of patients. There were many episodes of hypotension unmasked through continuous monitoring. Based on the advanced haemodynamic data provided it is possible that the underlying cause of a third of postoperative hypotensive episodes is vasodilation rather than hypovolaemia.Trial registry number: NCT04010058 (ClinicalTrials.gov) Date of registration: 08/07/2019.

Efficacy of goal-directed fluid therapy monitored by pulse-pressure variation using a continuous noninvasive arterial pressure monitoring system (the CNAPTM system) during parathyroidectomy in patients with end-stage renal failure – a randomised trial

IntroductionThere are no well-recognised guidelines for intraoperative fluid management in patients with end-stage renal failure (ESRF). Goal-directed fluid therapy (GDFT) is a concept of perioperative fluid management that improves patients’ prognosis. In this study, we assessed a GDFT protocol with monitoring of pulse pressure variation (PPV) in patients with ESRF undergoing parathyroidectomy.Material and methodsA total of 102 patients who underwent elective parathyroidectomy were randomised into a control group (restrictive group, n = 51), managed with a restricted fluid regimen, or a PPV group (GDFT group, n = 51), given a normal saline infusion, and they were monitored for changes in PPV. If PPV reached &gt; 13%, 250 ml of normal saline was administered over 15 min. Ephedrine was given to keep the mean arterial pressure &gt; 65 mm Hg. Haemodynamic variables in the perioperative period were recorded. The primary endpoint was the occurrence of postoperative hypotension.ResultsThe occurrence of postoperative hypotension (0 vs. 11.67%, p = 0.027) and complications (35.3% vs. 54.9%, p = 0.047) in the GDFT group was lower than in the restrictive group. The volume of saline infused during the operation was 364 (219–408) ml and 50 (50–50) ml, respectively (p = 0.001). Ephedrine was given to 16/51 (29.4%) patients of the GDFT group and 27/51 (52.9%) patients of the restrictive group (p = 0.027).ConclusionsThe use of GDFT with dynamic PPV monitoring in patients with ESRF undergoing parathyroidectomy could potentially be used to guide the administration of infused fluids, with the possibility of reducing the occurrence of postoperative hypotension.

Wearable skin-like optoelectronic systems with suppression of motion artifacts for cuff-less continuous blood pressure monitor.

According to the statistics of the World Health Organization, an estimated 17.9 million people die from cardiovascular diseases each year, representing 31% of all global deaths. Continuous non-invasive arterial pressure (CNAP) is essential for the management of cardiovascular diseases. However, it is difficult to achieve long-term CNAP monitoring with the daily use of current devices due to irritation of the skin as well as the lack of motion artifacts suppression. Here, we report a high-performance skin-like optoelectronic system integrated with ultra-thin flexible circuits to monitor CNAP. We introduce a theoretical model via the virtual work principle for predicting the precise blood pressure and suppressing motion artifacts, and propose optical difference in the frequency domain for stable optical measurements in terms of skin-like devices. We compare the results with the blood pressure acquired by invasive (intra-arterial) blood pressure monitoring for >1500 min in total on 44 subjects in an intensive care unit. The maximum absolute errors of diastolic and systolic blood pressure were ±7/±10 mm Hg, respectively, in immobilized, and ±10/±14 mm Hg, respectively, in walking scenarios. These strategies provide advanced blood pressure monitoring techniques, which would directly address an unmet clinical need or daily use for a highly vulnerable population.

A clinical study of the evaluation of hemodynamic status in mechanically ventilated critically ill patients by continuous non-invasive arterial pressure monitor

To evaluate the difference and correlation between continuous non-invasive arterial pressure (CNAP) monitor and pulse indicated continuous cardiac output (PiCCO) monitor on determination of hemodynamic parameters in mechanically ventilated critically ill patients, and to assess the feasibility of non-invasive monitoring of hemodynamics with CNAP. A prospective observation self-control study was conducted.The critically ill patients with mechanical ventilation who needed hemodynamics monitoring, and admitted to the fourth department of intensive care unit (ICU) of Fujian Provincial Hospital from June 2018 to March 2019 were enrolled. PiCCO catheter were inserted immediately after admission, the hemodynamic indexes were measured by thermodilution method, and mean arterial pressure (MAPPiCCO), cardiac index (CIPiCCO), pulse pressure variation rate (PPVPiCCO) and systemic vascular resistance index (SVRIPiCCO) were obtained at 0 hour and 24 hours respectively. Meanwhile, the above indexes (MAPCNAP, CICNAP, PPVCNAP and SVRICNAP) were measured with CNAP. All measurements were repeated thrice and average values were reported. The differences in above parameters between the two methods were evaluated. Pearson test was used for the correlation analysis and Bland-Altman analysis method was used for consistency test. Thirty-eight patients were enrolled into this study. One patient died within 24 hours was excluded, 2 patients were excluded due to withdrawing treatment within 24 hours, 2 patients were excluded because of atrial fibrillation, and 1 patient's data was lost due to technical problems. Thus, data from 32 patients were available for final analysis. There were 12 females and 20 males, aging 26-84 years old with the mean of (66.8±19.1) years old, body mass index (BMI) of (23.7±3.9) kg/m2, acute physiology and chronic health evaluation II (APACHE II) score of 19.5±5.3, sepsis-related organ failure assessment (SOFA) score of 9.7±4.1. There were no significant differences in CI or PPV between CNAP and PiCCO groups [CI (mL×s-1×m-2): 59.8±12.6 vs. 58.5±14.2, PPV: (14.7±6.8)% vs. (14.0±6.8)%, both P > 0.05]. MAP and SVRI measured by CNAP were significantly higher than those measured by PiCCO [MAP (mmHg, 1 mmHg = 0.133 kPa): 65.6±9.4 vs. 60.1±9.2, SVRI (kPa×s×L-1×m-2): 206.2±53.9 vs. 179.5±57.8, both P < 0.01]. The correlation analysis showed that MAP, CI, PPV and SVRI measured by the two methods were significantly positively correlated (r value was 0.624, 0.864, 0.835 and 0.655 respectively, all P < 0.05). Bland-Altman analysis showed that CNAP and PiCCO had a good consistency for the measurement of CI and PPV, the average differences were 1.2 mL×s-1×m-2 and 0.5% respectively, while the 95% confidence interval (95%CI) were -12.8-15.3 mL×s-1×m-2 and -7.1%-8.2% respectively. However, the consistency of MAP and SVRI measured by those two methods was poor, the average differences were 5.5 mmHg and 26.8 kPa×s×L-1×m-2 respectively, while the 95%CI was -10.4-21.3 mmHg and -64.5-118.0 kPa×s×L-1×m-2 respectively. CNAP was comparable with PiCCO when monitoring CI and PPV in mechanically ventilated critically ill patients; while the results of MAP and SVRI might be inaccurate, which should be interpreted correctly and carefully.

Analysis on the characteristics of postural blood pressure changes recorded with continuous non-invasive arterial pressure monitoring system and the correlative factors in elderly hospitalized patients

Objective: To explore the characteristics of postural blood pressure changes in elderly inpatients and the related factors of orthostatic hypotension (OH). Methods: This study was a clinical case control study. Two hundred and sixty-six elderly patients (≥60 years old), who were hospitalized between April 2016 and November 2017 in Geriatric Department of Peking University First Hospital, were included. They were divided into direct standing group and indirect standing group. Direct standing group involved 102 patients, they changed posture from supine directly to standing position, and the blood pressures at the moments of supine, immediately after standing and the first, second, and third minute after standing were recorded by continuous noninvasive arterial pressure (CNAP) system. Indirect standing group involved 164 patients, and they changed posture from supine to sitting for 3 minutes, and then changed to standing position. Blood pressures at the moments of supine, immediately after sitting, the third minute after sitting, immediately after standing and the third minute after standing was recorded by CNAP. Blood pressure changes after different postural changes mode and the rates of OH were compared. The related factors of OH was analyzed by binary logistic regression analysis. Results: The lowest systolic blood pressures (SBP) mostly occurred immediately after postural change: immediately after standing for direct standing group (86.3%(88/102)), and immediately after sitting for indirect standing group (59.1%(97/164)). The lowest diastolic blood pressures (DBP) mostly occurred immediately after standing in the two groups: 87.3%(89/102) for direct standing group and 43.3% (71/164) for indirect standing group. The maximum SBP drop (SBP of supine minus the lowest SBP during postural changes) of direct standing group was significantly higher than indirect standing group (median 20.5(14.0, 29.3) vs. 18.0(11.0, 26.0) mmHg (1 mmHg=0.133 kPa, P<0.05). The rates of OH occurred immediately and within 3 minutes from supine to standing position were significantly higher in direct standing group than in indirect standing group (65.7% (67/102) vs. 43.9% (72/164), and 70.6% (72/102) vs. 49.4% (81/164), both P<0.05). Binary logistic regression analysis showed that brachial-ankle pulse wave velocity was positively associated with OH after a transition from supine to standing position (immediately and within 3 minutes, OR=1.002 (95%CI 1.000-1.004), 1.003 (95%CI 1.001-1.006), P=0.014, 0.006) in direct standing group. Conclusions: OH is common in elderly hospitalized patients. The most obvious blood pressure changes are likely to occur immediately after position changes. Adding a sitting position during the transition of supine to standing position may decrease the amplitude of SBP drop. Brachial-ankle pulse wave velocity is associated with OH after the transition from the supine to standing position in the elderly inpatients.

Efficacy of a continuous non-invasive arterial blood pressure monitor system for bronchoscope diagnosis and treatment under general anesthesia

Objective To compare continuous non-invasive arterial blood pressure (CNAP) monitoring with non-invasive blood pressure (NIBP) monitoring in anesthesia monitoring application value of bronchoscope diagnosis and treatment, and to find whether the CNAP can improve the detection rate of hypotension and detect low blood pressure earlier so that improve the safety of patients. Methods Twenty patients undergoing bronchoscope diagnosis and treatment under general anesthesia from outpatient were included in this study. The NIBP monitoring was put on one side of the upper limb and the CNAP monitoring was connected to the other side upper limb before inducement of general anesthesia. Both connections were kept until the end of operation. The systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) of the CNAP were recorded one time per minute whereas the SBP, DBP and MAP of NIBP were recorded one time every 3 min. The low blood pressure (SBP<80 mmHg, 1 mmHg=0.133 kPa) frequency of CNAP and NIBP were respectively counted. The low blood pressure detection rate and the hypotension checkout time of NIBP and CNAP were calculated respectively. The consistency and correlation between the two blood pressure measurements were compared. At the same time, the complications of the two methods of monitoring were recorded and compared. Results The low blood pressure detection rate of CNAP and NIBP was 17.2% and 14.7% (P<0.05). The hypotension checkout time of CNAP and NIBP were (1.2±0.4) min and (3.0±0.0) min respectively (P<0.05). The SBP, DBP and MAP bias of CNAP and NIBP measurement were (1.5±8.8), (1.1±8.2) mmHg and (1.3±7.1) mmHg respectively. Consistency limits were -18.70-15.70 mmHg, -17.20-14.90 mmHg and -15.30-12.70 mmHg respectively. The proportion within the scope of the consistency of its corresponding boundary were 96.70%, 97.10% and 97.10% respectively. The correlation coefficients of SBP, DBP and MAP measured by CNAP and NIBP were 0.910, 0.861 and 0.941 respectively (P<0.05). None of the patients had complications. Conclusions CNAP is more sensitive and timely in detecting hypotension. It has higher consistency and more correlation than NIBP. Thus, CNAP can improve the safety of anesthesia monitoring for bronchoscope diagnosis and treatment. Key words: Continuous non-invasive arterial blood pressure monitoring; Bronchoscope diagnosis and treatment; Anesthesia, general

Changes of blood pressure following initiation of physical inactivity and after external addition of pulses to circulation

PurposeTo determine whether an innovative, motorized, wellness device that effortlessly produces physical activity (JD) can mitigate the hypertensive effects of prolonged sitting or lying down.MethodsTwenty-two normotensive and hypertensive adults of both genders gave informed consent to participate in a randomized controlled crossover study of a passive simulated jogging device (JD) in both supine and seated postures. Each study participant was monitored with a continuous non-invasive arterial pressure monitoring device (CNAP) over 60 min. The initial 10 min served as baseline for each posture. The subjects were randomized to begin with either JD or SHAM control for 30 min, and monitoring was continued for an additional 10 min in one posture; three days later posture and order of JD or SHAM were changed.ResultsIn both seated and supine postures, SHAM was associated with a significant rise in blood pressure (BP) which was observed within 5–10 min; it continued to rise or remain elevated for over a 40-min observation period. In contrast, JD produced a significant decrease in both systolic and diastolic blood pressure in both postures. During recovery in seated posture JD decreased systolic and diastolic BP by − 8.1 and − 7.6 mmHg, respectively. In supine posture, a similar decrease in BP occurred.ConclusionsThere is rapid onset of increase in systolic and diastolic BP with physical inactivity in both supine and seated postures. Administration of JD significantly decreased BP in both postures. Further studies are needed to assess long-term effectiveness.