Non-invasive Cardiac Monitoring Research Articles

Correlation and concordance of carotid Doppler ultrasound and echocardiography with invasive cardiac output measurement in critically ill patients

BackgroundCritical care management heavily relies on accurate cardiac output (CO) measurement. Echocardiography has been a mainstay in non-invasive cardiac monitoring; however, its comparability to invasive methods warrants further exploration. Recent studies have suggested the potential of carotid Doppler measurements as a promising approach to estimate CO. Despite this potential, the literature presents mixed outcomes regarding its reliability and accuracy. This study aims to evaluate the correlation and concordance between carotid Doppler ultrasonography and invasive hemodynamic monitoring in estimating CO in critically ill patients. Furthermore, it assesses the concordance and correlation between echocardiography CO and the standard invasive CO measurements.MethodsThis concordance study involved critically ill adults requiring invasive CO measurement. Patients with arrhythmias, severe valvulopathy, pregnancy, and poor acoustic window were excluded. Statistical analyses comprised univariate analysis, Wilcoxon signed-rank test, Spearman correlation, and intraclass correlation coefficient. Ethical approval was granted by the institution’s ethics committee.ResultsA total of 49 critically ill patients were included, predominantly male (63.27%), with a median age of 57 years. Diagnoses included subarachnoid hemorrhage (53.06%) and heart failure (8.16%). Mean cardiac index was 3.36 ± 0.81 L/min/m2 and mean cardiac output was 5.98 ± 1.47 L/min. Spearman correlation coefficient between echocardiography and invasive CO measurements was 0.58 (p-value = p < 0.001), with an ICC of 0.59 for CO and 0.52 for cardiac index. Carotid measurements displayed no significant correlation with invasive CO.ConclusionThere is a moderate correlation and concordance between echocardiography and invasive CO measurements. There is no significant correlation between carotid variables and invasive CO, underscoring the necessity for cautious interpretation and application, particularly in patients with distinctive cerebral blood flow dynamics.

ASIC design of power and area efficient programmable FIR filter using optimized Urdhva-Tiryagbhyam Multiplier for impedance cardiography

Impedance cardiography (ICG) is a rapidly growing non-invasive cardiac health monitoring approach. Synchronous detection of ICG requires an FIR filter to remove the high-frequency carrier signal. Low power consumption and compact area are critical considerations in the design of portable biomedical systems. This paper proposes a novel product quantization-based optimization strategy for the Urdhva Tiryagbhyam Sutra-based multiplier architecture. This paper presents an ASIC design of a low-power and low-area 64th-order programmable FIR filter architecture using the optimized Urdhva Tiryagbhyam Multiplier. The programmable architecture empowers medical practitioners to select the carrier frequency at which the ICG analysis will be performed. The elimination of redundant multipliers from the design based on the filter coefficients is demonstrated. The programmable Vedic FIR filter architecture (described in VHDL) is implemented on the Basys-3 FPGA board for rapid prototyping. The RTL-to-GDSII flow has been completed using Cadence digital design and sign-off tools for the SCL-180 nm technology. The results indicate that the proposed filter architecture occupies 41.33% less area and 42.16% lower power consumption than the contemporary designs described in the literature.

Use of non-invasive cardiac monitoring to guide discontinuation of postpartum magnesium sulfate in individuals with preeclampsia with severe features

ObjectivesTo determine the utility of using total peripheral systemic vascular resistance assessed using non-invasive cardiac monitor for individualizing the duration of postpartum magnesium sulfate in individuals with preeclampsia with severe features. Study designSingle center pilot randomized controlled trial in which singleton pregnant individuals with preeclampsia with severe features were randomized to 24 h of postpartum magnesium sulfate per standard of care (control group) or individualized duration of postpartum magnesium sulfate based on reduction in post-delivery systemic vascular resistance (intervention group). Systemic vascular resistance was assessed with non-invasive cardiac monitoring using the Cheetah® system. A 30 % reduction (maintained for 1 h) from baseline post-delivery systemic vascular resistance was used as a cutoff for discontinuation of postpartum magnesium sulfate. Our primary outcome was duration of postpartum magnesium sulfate use in hours. Secondary outcomes included a composite of maternal morbidities associated with preeclampsia. ResultsOf 53 individuals enrolled, we excluded 6 from this analysis due to insufficient data to assess primary outcome. Baseline characteristics of the control (n = 26) and intervention (n = 21) groups were similar. Six (28.6 %) individuals in intervention group met the systemic vascular resistance criteria and had their postpartum magnesium sulfate discontinued before 24 h. The duration of postpartum magnesium sulfate infusion was shorter in the intervention group (21.6 ± 4.7 h; range: 7–24 h) compared with control group (24 h, p = 0.02). There was no difference in secondary outcomes between the two groups. There was no difference in adverse outcomes in individuals that had magnesium discontinued earlier than 24 h. ConclusionNon-invasive monitoring of systemic vascular resistance can be a valuable tool to individualize the duration of postpartum magnesium sulfate for preeclampsia with severe features. These findings should be conformed in a larger trial.

A Patient‐Centered Approach to Cardiac Monitoring After Cryptogenic Stroke: A Review

Due to the variety of cardiac monitoring devices available after cryptogenic stroke to screen for atrial fibrillation, there is a need to understand the challenges and perceptions of these devices for patients. This article reviews in detail the cardiac monitoring technologies available to screen for atrial fibrillation after cryptogenic stroke/transient ischemic attack, with a focus on what is known regarding patient preferences and compliance in real‐world settings. As the optimal type of device and duration of time to screen for atrial fibrillation after cryptogenic stroke continues to be studied, a shared decision‐making approach that incorporates patient preferences with regard to the monitoring device chosen should be considered. Clinicians should explain to patients the uncertainty about the clinical impact of invasive monitoring, and future studies should aim to qualitatively delineate the viewpoints and comfort levels of patients with stroke regarding the use of implantable versus noninvasive cardiac monitoring.

The utility of heart rate and heart rate variability to identify limits of tolerance to moderate-intensity work in the heat: a secondary analysis.

We investigated the utility of heart rate (HR) and heart rate variability (HRV) for identifying individuals who may terminate work early due to excessive heat strain. Forty-eight men and women (median=36 years; Q1=20 years; Q3=54 years) attempted 180 min of moderate-intensity work at a fixed metabolic rate (∼200W/m2; ∼3.5 METs) in a hot environment (wet-bulb globe temperature: 32 °C). Receiver operating characteristics (ROC) curves were used to identify the ability of indices of HR (absolute HR, percentage of maximum HR, percentage of HR reserve) and HRV (root-mean-square of successive differences (RMSSD), high-frequency power, and detrended fluctuation analysis component alpha 1 (DFA α1)) to discriminate between participants who completed the 180 min work bout or terminated prematurely. Participants who terminated work prematurely (n=26) exhibited higher HR and percentage of HR measures, as well as reduced RMSSD and DFA α1 after the first hour of work compared to participants who completed the bout. The discriminative utility of HR and HRV indices was strongest within the first hour of work, with percentage of HR reserve demonstrating excellent discriminative power (ROC area under curve (AUC) of 0.8). Stratifying participants by age and sex improved ROC AUC point estimates for most indices, particularly in female participants. The study provides preliminary evidence supporting the use of noninvasive cardiac monitoring for predicting work tolerance in healthy individuals exposed to occupational heat stress. HR and percentage of HR reserve were suggested to discriminate work termination most effectively. Further investigations are warranted to explore the influence of individual factors and refine the discriminative thresholds for early identification of excessive occupational heat strain.

OGC P50 Evaluating the outcomes of routine level one ward care post major oesphago-gastric surgery

Abstract Background Oesophago-gastric cancer resections are complex operations. Many centres routinely manage patients in higher acuity settings such as surgical HDU, ITU or fast track beds. The UK has 2.4 critical care beds per 1000, compared to an average of 5 per 1000 across OECD-EU nations. The COVID-19 pandemic has also had a significant impact on availability of these beds. Patients in our unit are routinely admitted to a standard level one surgical bed with continuous non-invasive cardiac monitoring and nursing care ratio of 1 to 5. This has been in practice for over 10 years with good outcomes. Methods Consecutive major oesophago-gastric resections between April 2020 and March 2023 in a single tertiary unit were included. Patients were split into two groups: Patients who were admitted directly to the surgical ward or had a planned admission to ITU based on pre-operative assessment and routine Integrated Cardiopulmonary Exercise Testing (CPEX) outcomes were considered to have completed a standard pathway. The primary outcome was unplanned ITU admission rate. Secondary outcomes included: total length of stay (TLOS), 30- and 90-day mortality. Results 238 patients (187 M: 51 F) were identified with a median age of 69 (33 – 84 years). The resections performed were Ivor Lewis oesophago-gastrectomy (ILGO) (n=196, 81%), total/extended total (n=30), subtotal (n=10) or distal gastrectomy (n=3). 34 patients were admitted to ITU, of which 23 were unplanned (9.2%) and all had undergone an ILGO. The median TLOS and mortality data are outlined in Table 1, with &amp;lt;1% 30 and 90-day mortality for patients on the standard pathway. The median ITU length of stay was 5 days (1 – 48 days) with reasons for admission listed in Table 2. Conclusions Major oesophago-gastric cancer resections can be managed safely in the early post-operative period, outside of higher acuity care settings with good outcomes.

Randomized comparison of effects of two different remifentanil dose on surgical conditions during endoscopic sinus surgery

BackgroundThe combination of propofol and remifentanil results in better surgical field conditions during endoscopic sinus surgery than inhalation anesthesia. This study compared surgical field conditions between two groups receiving low or high concentration of remifentanil and hemodynamic variables using non-invasive cardiac monitoring.MethodsFifty-four patients between ASA I or II, were randomly assigned to either the high-concentration remifentanil group (HR), effect-site concentration of 8 ng/mL or the low-concentration remifentanil group(LR), effect-site concentration of 4 ng/mL. Surgical condition was evaluated using the Boezaart Surgical Field Grading Scale presented by Boezaart. Cardiac output was measured using non-invasive cardiac monitoring (CSN-1901).ResultsIn terms of surgical conditions, the HR group showed significantly lower values than the LR group (p = 0.021) at 90 min after the start of surgery. Heart rate was significantly lower in the HR group than the LR group at 30, 60, and 90 min after the start of surgery (30 min; p = 0.005, 60 min; p = 0.002, 90 min; p = 0.001). There was a statistically significant decrease of cardiac output in the HR group compared to the LR group immediately after endotracheal intubation and at 30, 60, and 90 min after the start of surgery (Base; P = 0.222, Intubation; P = 0.016, 30 min; p = 0.014, 60 min; P = 0.012, 90 min; P = 0.008). However, in the case of stroke volume, there was no significant difference between the two groups in all measurements.ConclusionWhen comparing the HR group and the LR group, the surgical condition was improved at 90 min after the start of surgery. MAP was lower in the HR group and this was a result of reduction in cardiac output primarily attributed to the decrease in heart rate rather than a decrease in stroke volume.Trial registrationClinical Trial Registry of the Republic of Korea (KCT0006453).

Telemedicine in Heart Failure in the COVID-19 and Post-Pandemic Era: What Have We Learned?

Numerous studies showed that patients with heart failure (HF) and COVID-19 are at high risk of in-hospital complications and long-term mortality. Changes in the organisation of the medical system during the pandemic also worsened access to standard procedures, increasing the general mortality in HF and forcing the systems to be reorganised with the implementation and development of telemedical technologies. The main challenges for HF patients during the pandemic could be solved with new technologies aimed to limit the risk of SARS-CoV-2 transmission, optimise and titrate the therapy, prevent the progression and worsening of HF, and monitor patients with acute HF events in the course of and after COVID-19. Dedicated platforms, phone calls or video conferencing and consultation, and remote non-invasive and invasive cardiac monitoring became potential tools used to meet the aforementioned challenges. These solutions showed to be effective in the model of care for patients with HF and undoubtedly will be developed after the experience of the pandemic. However, the multitude of possibilities requires central coordination and collaboration between institutes with data protection and cost reimbursement to create effective mechanisms in HF management. It is crucial that lessons be learned from the pandemic experience to improve the quality of care for HF patients.

Monitoring for arrhythmia in transthyretin cardiac amyloidosis with remote patch devices

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Transthyretin cardiac amyloidosis (ATTR-CA) is associated with an increased incidence of arrhythmias. We hypothesized that non-invasive, two-week outpatient cardiac rhythm monitoring of patients with ATTR-CA would detect high rates of ventricular tachycardia and atrial fibrillation/flutter (AF). Purpose To characterize arrhythmia in patients with ATTR-CA on two-week, non-invasive cardiac rhythm monitors. Methods 38 patients with ATTR-CA (mean age 76.9 SD 10.0 years, 89.5% male) who underwent two-week remote external patch monitoring were included in this single center retrospective study. An age-matched control group included 38 patients (mean age 73.9 SD 12.3, 76.3% male) who underwent the same cardiac rhythm monitoring as part of neurological workups. Results NSVT was detected on the remote monitor in 81.6% of ATTR-CA patients and AF was detected in 26.3% of patients. ATTR-CA was associated with higher rates of NSVT and AF compared to the control group (28.9% with NSVT and 5.3% with AF). As seen in Figure 1, there were only three ATTR-CA patients without either AF, NSVT, advanced atrioventricular block, or a significant pause detected on remote monitor. Among the ATTR-CA group, at median 45 weeks follow-up, there were 4 heart failure hospitalizations, 2 cardiovascular events (1 episode of sustained VT and 1 stroke), 6 permanent pacemakers placed, and 3 implantable cardioverter-defibrillators placed, including one for sustained VT. NSVT and AF were not associated with a composite of these adverse outcome. Conclusion ATTR-CA was associated with high rates of NSVT and AF on noninvasive remote monitors. While evidence regarding the management of arrhythmias, particularly NSVT/VT, in ATTR-CA remains limited, two-week noninvasive cardiac monitoring can be considered to aid in risk stratification for both atrial and ventricular arrhythmias in ATTR-CA.

Use of non-invasive cardiac monitoring to guide discontinuation of postpartum magnesium sulfate in severe preeclampsia

Use of non-invasive cardiac monitoring to guide discontinuation of postpartum magnesium sulfate in severe preeclampsia

Effects of trunk posture on cardiovascular and autonomic nervous systems: A pilot study.

Objective: Although regular and moderate physical activity has been shown to improve the cardiovascular and autonomic nervous systems, little has been done to study the effects of postural changes in the movement on the heart and autonomic nervous system. To uncover changes in cardiac function and autonomic nerves induced by different underlying posture transitions and explore which trunk postures lead to chronic sympathetic activation. Therefore, this study investigated the effects of trunk posture on the cardiovascular and autonomic nervous systems. Methods: Twelve male subjects (age 24.7 ± 1.3) underwent this study. The non-invasive cardiac output NICOM monitoring equipment and the FIRSTBEAT system are used to dynamically monitor seven trunk postures in the sitting position simultaneously (neutral position, posterior extension, forward flexion, left lateral flexion, right lateral flexion, left rotation, right rotation). Each posture was maintained for 3min, and the interval between each movement was 3min to ensure that each index returned to the baseline level. Repeated analysis of variance test was used to compare and analyze the differences in human cardiac function, heart rate variability index, and respiratory rate under different postures. Results: Compared with the related indicators of cardiac output in a neutral trunk position: the cardiac index (CI) was significantly reduced in forwarding flexion and left rotation (3.48 ± 0.34 vs. 3.21 ± 0.50; 3.48 ± 0.34 vs. 3.21 ± 0.46, ΔL/(min/m2)) (p = 0.016, p = 0.013), cardiac output decreased significantly (6.49 ± 0.78 vs. 5.93 ± 0.90; 6.49 ± 0.78 vs. 6.00 ± 0.96, ΔL/min) (p = 0.006, p = 0.014), the stroke volume (stroke volume)decreased significantly (87.90 ± 15.10 vs. 81.04 ± 16.35; 87.90 ± 15.10 vs. 79.24 ± 16.83, Δml/beat) (p = 0.017, p = 0.0003); heart rate increased significantly in posterior extension (75.08 ± 10.43 vs. 78.42 ± 10.18, Δbeat/min) (p = 0.001); left rotation stroke volume index (SVI) decreased significantly (47.28 ± 7.97 vs. 46.14 ± 8.06, Δ ml/m2) (p = 0.0003); in the analysis of HRV-related indicators, compared with the neutral trunk position, the LF/HF of the posterior extension was significantly increased (1.90 ± 1.38 vs. 3.00 ± 1.17, p = 0.037), and the LF/HF of the forward flexion was significantly increased (1.90 ± 1.38 vs. 2.85 ± 1.41, p = 0.041), and the frequency-domain index LF/HF of right rotation was significantly increased (1.90 ± 1.38 vs. 4.06 ± 2.19, p = 0.008). There was no significant difference in respiratory rate (p > 0.05). Conclusion: A neutral trunk is the best resting position, and deviations from a neutral trunk position can affect the cardiovascular and autonomic nervous systems, resulting in decreased stroke volume, increased heart rate, and relative activation of sympathetic tone.

Continuous cardiac rhythm monitoring post-stroke: A feasibility study in REGARDS

ObjectivesCardiac rhythm monitoring is increasingly used after stroke. We studied feasibility of telephone guided, mail-in ambulatory long-term cardiac rhythm monitoring in Black and White stroke survivors. Materials and methods;We contacted 28 participants of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who had an ischemic stroke during follow-up. After obtaining informed consent by telephone, a noninvasive 14-day cardiac rhythm monitoring device (ZIO® XT patch; iRhythm Technologies, San Francisco, CA) was mailed to each participant. We evaluated the results of telephone consent, follow-up calls, compliance and wear time as the primary objective. Secondarily, we reported prevalence of atrial and ventricular arrhythmias. ResultsThe majority of those contacted (20/28 = 71%) agreed to enroll in the monitoring study. Non-participation was nominally more common in Black than White participants; 6/16 (37.5%) vs. 2/12 (17%). Of those who agreed, 15 participants (75%, 6 Black, 9 White) completed ambulatory monitoring with mean wear time 12.9 ± 2.5 days. Arrhythmias were observed in two-thirds of the 15 participants: AF in 2, brief atrial tachycardia in 12, NSVT in 2, premature ventricular contractions in 3, and pause or atrioventricular block in 2. ConclusionsNon-invasive rhythm monitoring was feasible in this pilot from a large, national cohort study of stroke survivors that employed a telephone guided, mail-in monitoring system, and these preliminary results suggest a high prevalence of arrhythmias. Increased emphasis on recruitment strategies for Black stroke survivors may be required. We demonstrated a high yield of significant cardiac arrhythmias among post-stroke participants who completed monitoring.

Mechanism-Driven Modeling to Aid Non-invasive Monitoring of Cardiac Function via Ballistocardiography.

Left ventricular (LV) catheterization provides LV pressure-volume (P-V) loops and it represents the gold standard for cardiac function monitoring. This technique, however, is invasive and this limits its applicability in clinical and in-home settings. Ballistocardiography (BCG) is a good candidate for non-invasive cardiac monitoring, as it is based on capturing non-invasively the body motion that results from the blood flowing through the cardiovascular system. This work aims at building a mechanistic connection between changes in the BCG signal, changes in the P-V loops and changes in cardiac function. A mechanism-driven model based on cardiovascular physiology has been used as a virtual laboratory to predict how changes in cardiac function will manifest in the BCG waveform. Specifically, model simulations indicate that a decline in LV contractility results in an increase of the relative timing between the ECG and BCG signal and a decrease in BCG amplitude. The predicted changes have subsequently been observed in measurements on three swine serving as pre-clinical models for pre- and post-myocardial infarction conditions. The reproducibility of BCG measurements has been assessed on repeated, consecutive sessions of data acquisitions on three additional swine. Overall, this study provides experimental evidence supporting the utilization of mechanism-driven mathematical modeling as a guide to interpret changes in the BCG signal on the basis of cardiovascular physiology, thereby advancing the BCG technique as an effective method for non-invasive monitoring of cardiac function.

A gold nanowire-integrated soft wearable system for dynamic continuous non-invasive cardiac monitoring

Blood pressure (BP) is a cardiovascular parameter which exhibits significant variability. Whilst continuous BP monitoring would be of significant clinical utility. This is particularly challenging outside the hospital environment. New wearable cuff-based and cuffless BP monitoring technologies provide some capacity, however they have a number of limitations including bulkiness, rigidity and discomfort, poor accuracy and motion artefact. Here, we report on a lightweight, user-friendly, non-invasive wearable cardiac sensing system based on deformation-insensitive conductive gold nanowire foam (G-foam) and pressure-sensitive resistive gold nanowire electronic skin (G-skin). The G-foam could serve as a new soft dry bioelectrode for electrocardiogram (ECG) monitoring; a new soft button-based G-skin design could avoid manual holding for continuous pulse recording. They could be integrated seamlessly with everyday bandage for facile wireless recording of ECG and artery pulses under real-word dynamic environments including walking, running, deep squatting, and jogging. Further machine learning algorithm was developed for estimation of systolic and diastolic BP, showing comparable accuracy to commercial cuff-based sphygmomanometer. The measured dynamic BP changes correlated well with the volunteer’s daily activities, indicating the potential applications of our soft wearable systems for real-time diagnostics of cardiovascular functions in complex dynamic real-world setting.

Stroke Volume Estimation from Respiratory Inductive Plethysmography: Double Empirical Decomposition

In this study, we have developed a “double-empirical mode decomposition algorithm” to estimate cardiac stroke volume from respiratory inductive plethysmography (RIP) signals. The algorithm consists of first an ensemble empirical mode decomposition (EEMD) to extract the cardiorespiratory components. Then, it is followed by an empirical mode decomposition (EMD) to extract only the cardiac components. This double approach permits (a) solving problems of mixing between cardiac and respiratory components (mode and scale mixing), (b) cardiogenic oscillations extraction in the respiratory inductive plethysmography signal, and (c) subsequent estimation of stroke volume. The algorithm is applied to simulated and real RIP signals. The simulated signals are generated by a cardiorespiratory model previously published by the authors. The real signals are measured via a developed inductive vest. In the real case, the values of estimated stroke volumes are compared to the values obtained by thoracocardiographic filter-based method. In the simulated case, the values are compared to the simulated cardiac activity. The results of comparison through Bland and Altman indicate an error lying in the range ±10%. In contrast to thoracocardiography, the proposed method consists of a promising tool for continuous noninvasive adaptive cardiac monitoring that does not need adjusting parameters or cut-off based on ECG. Also, in comparison to echocardiography and impedance-based methods, it does not necessitate the presence of an expert and is not too sensitive to current penetration.

Benefit of continued noninvasive cardiac monitoring in geriatric trauma: A retrospective review of geriatric pelvis, hip, and femur fractures and analysis of cardiac events during immediate post-traumatic course.

Objective:The geriatric population suffers from a predisposition to cardiac events due to physiologic changes commonly associated with aging. The majority of the trauma population seen at our facility is within the geriatric population (greater than 65 years old). Therefore, this study was aimed to determine which of those preexisting factors were associated with an increased risk for developing cardiac event. By assessing those risks, we hoped to determine a timeline for the highest risk of cardiac event occurrence, in order to identify a safe period of when cardiac monitoring was indicated.Methods:A retrospective study performed over 6 months reviewing geriatric trauma patients with hip, pelvis, or femur fractures, n = 125. A list of predetermined risk factors including comorbidities, pathologies, laboratory values, electrocardiogram findings, and surgery was crossed with the patient’s records in order to identify factors for increased risk of cardiac event. Once patients who had documented cardiac events were identified, a temporal pattern of cardiac event occurrence was analyzed in order to determine a period when noninvasive cardiac monitoring should remain in place.Results:In 125 patients, 40 cardiac events occurred in 30 patients. The analyzed variables with statistically significant associations for having a cardiac event were comorbidities (p = 0.019), elevated body mass index (p = 0.001), abnormal initial phosphorus (p = 0.002), and an electrocardiogram finding of other than normal sinus rhythm (p = 0.020). Of the identified cardiac events, we found that by hospital day 3 68% of cardiac event had occurred, with 85% by hospital day 4, 95% by day 5, and 100% within the first 7 days of admission.Conclusion:Patient history of cardiac comorbidities, elevated body mass index, abnormal phosphorus, and abnormal electrocardiogram findings were found to be significant risk factors for cardiac event development in geriatric trauma. All recorded events in our study occurred within 7 days of the initial trauma.

The Feasibility and Applications of Non-invasive Cardiac Monitoring in Obese Patients Undergoing Day-case Surgery: Results of a Prospective Observational Study

Aims: This prospective observational study evaluates the utility of non-invasive cardiac monitoring in obese patients in the day-surgery case, considering factors, such as Body Mass Index (BMI) and anaesthesia technique. Background: Obese patients are more likely to be admitted to hospital or to get hospitalized because they are more prone to concomitant diseases and obesity itself is not a contraindication to day surgery. Obese patients are a high-risk patient population that may particularly benefit from monitoring perioperative haemodynamic variations. Methods: In this observational study, we compared haemodynamic variations between overweight or obese and normal weight patients undergoing day-case surgery. We adopted NICOM® as a non-invasive cardiac output monitoring. Objective: The aim of the current study was to investigate the haemodynamic impact of BMI and anaesthesia technique during day-case surgery procedures. The other goal was to evaluate the feasibility and applications of non-invasive cardiac output monitoring among the obese population in day-surgery. Results: 74 patients were included in the study. 34 were overweight or obese (weight 84 ± 10 kg, height 160 ± 10 cm, BMI ≈ 30 kg/m2), 40 were normal weight (weight 63 ± 15 kg, height 160 ± 10 cm, BMI ≈ 22 kg/m2). Compared to normal-weight patients, obese patients show an increase in blood pressure with a return to baseline values at the end of surgery (p &lt; 0.05). The Cardiac Output (CO) shows a similar trend, whereas the heart rate is normal. A decrease in the Cardiac Index (CI) during the operation was noticed in both groups, the one in obese patients (p = 0.24) being greater. In the same way, the Stroke Volume Index (SVI) was lower in obese patients during surgery (p &lt; 0.05). In spinal anaesthesia, the Total Peripheral Resistance Index (TPRI) was not statistically different between the groups of study. As for the TPRI in obese patients, we reported values similar to the ones in non-obese patients in spinal anaesthesia. In local anesthesia, TPRI was higher in obese patients than in non-obese. Conclusion: Cardiovascular alterations in relation to obesity include an increase in blood pressure, CO and SV. An inadequate monitoring of haemodynamic parameters is a risk factor for perioperative complications. NICOM® provides a continuous, non-invasive haemodynamic measurement.

Quality Improvement in Atrial Fibrillation detection after ischaemic stroke (QUIT-AF)

Paroxysmal atrial fibrillation (PAF) is a frequent cause of recurrent stroke but can be difficult to detect because of its episodic and often asymptomatic nature. We sought to improve rate of PAF detection through a quality improvement project (QIP) to deliver early prolonged inpatient cardiac monitoring on the stroke unit (SU). A structured protocol for cardiac monitoring using 5-day event recorders was established. 'In-house' cardiac monitoring was implemented. Performance data on this change in service was analysed prospectively and summary statistics obtained. One-hundred and two ischaemic stroke (IS) patients undertook 5-day event recorder monitoring. Provision of monitors as an inpatient (IP) increased from 20% (pre-QIP pilot 2018) to 65.7% (during QIP). New AF was detected in 15 patients (14.7% vs 8.6% pre-QIP pilot 2018) with majority of new AF (13 patients; 19%) detected when monitors applied early (IP) after IS. Although this study had a number of limitations, it did demonstrate that early and prolonged non-invasive IP cardiac monitoring could be delivered 'in-house' on the SU and improve AF detection rates.

Perioperative non-invasive versus semi-invasive cardiac index monitoring in patients with bariatric surgery \u2013 a prospective observational study

BackgroundIn morbidly obese patients undergoing laparoscopic bariatric surgery, the combination of obesity-related comorbidities, pneumoperitoneum and extreme posture changes constitutes a high risk of perioperative hemodynamic complications. Thus, an advanced hemodynamic monitoring including continuous cardiac index (CI) assessment is desirable. While invasive catheterization may bear technical difficulties, transesophageal echocardiography is contraindicated due to the surgical procedure. Evidence on the clinical reliability of alternative semi- or non-invasive cardiac monitoring devices is limited. The aim was to compare the non-invasive vascular unloading to a semi-invasive pulse contour analysis reference technique for continuous CI measurements in bariatric surgical patients.MethodsThis prospective observational study included adult patients scheduled for elective, laparoscopic bariatric surgery after obtained institutional ethics approval and written informed consent. CI measurements were performed using the vascular unloading technique (Nexfin®) and semi-invasive reference method (FloTrac™). At 10 defined measurement time points, the influence of clinically indicated body posture changes, passive leg raising, fluid bolus administration and pneumoperitoneum was evaluated pre- and intraoperatively. Correlation, Bland-Altman and concordance analyses were performed.ResultsSixty patients (mean BMI 49.2 kg/m2) were enrolled into the study and data from 54 patients could be entered in the final analysis. Baseline CI was 3.2 ± 0.9 and 3.3 ± 0.8 l/min/m2, respectively. Pooled absolute CI values showed a positive correlation (rs = 0.76, P < 0.001) and mean bias of of − 0.16 l/min/m2 (limits of agreement: − 1.48 to 1.15 l/min/m2) between the two methods. Pooled percentage error was 56.51%, missing the criteria of interchangeability (< 30%). Preoperatively, bias ranged from − 0.33 to 0.08 l/min/m2 with wide limits of agreement. Correlation of CI was best (rs = 0.82, P < 0.001) and percentage error lowest (46.34%) during anesthesia and after fluid bolus administration. Intraoperatively, bias ranged from − 0.34 to − 0.03 l/min/m2 with wide limits of agreement. CI measurements correlated best during pneumoperitoneum and after fluid bolus administration (rs = 0.77, P < 0.001; percentage error 35.95%). Trending ability for all 10 measurement points showed a concordance rate of 85.12%, not reaching the predefined Critchley criterion (> 92%).ConclusionNon-invasive as compared to semi-invasive CI measurements did not reach criteria of interchangeability for monitoring absolute and trending values of CI in morbidly obese patients undergoing bariatric surgery.Trial registrationThe study was registered retrospectively on June 12, 2017 with the registration number NCT03184272.

Identification of the Vibrations Corresponding with Heart Sounds using Vibrational Cardiography.

Automatically identify the vibrations corresponding to both heart sounds. Cardiac activity was monitored for 15 subjects while at rest, during exertion, and while performing static breath holds. The subjects consisted of 6 males and 9 females between the ages of 18-39 years with no known cardiorespiratory ailments. Motion corresponding to the heart sounds was identified using vibrational cardiography (VCG). The waveforms were processed to obtain quantities associated with their linear jerk and rotational kinetic energy. The ability to identity the first vibration was evaluated using the heart rate as a figure of merit. Its correlation with electrocardiography (ECG) measurements produced a r2 coefficient of 0.9887. The second vibration was compared with impedance cardiography (ICG) based on its delay from the ECG R-peak, and the fraction of the beat duration occupied by left ventricular ejection time. The comparisons produced r2 values of 0.251 and 0.2797, respectively. The vibrations corresponding to both primary heart sounds have the potential to be analyzed using VCG. This study provides evidence of the feasibility of using VCG in identifying mechanical cardiovascular function. It facilitates non-invasive cardiac health monitoring in daily life.