Heart rate measurement through carotid pulse by primary school children / Medición de la frecuencia cardíaca mediante pulso carotídeo por niños de primaria

This study aimed to determine whether primaryschool children can accurately monitor their heart rate (HR) through manual pulse measurement. Children aged 9 to 12 years manually assessed their HR through the carotid pulse three times in a physical education session; lying down, after submaximal effort and one minute later. Simultaneously, HR was measured by pulsometers. Of 417 children (10.58±0.93 years, 44.8% girls), 40% provided accurate values (<10% error). Concordance analysis showed wide limits of agreement (95% of measurements between 44.76% below and 78.64% above actual HR values). Sex, age and level of effort had no significant influence on the results. Primary school children are not able to accurately measure their HR through the carotid pulse (AU)

Este estudio tuvo como objetivodeterminar si los niños de primaria pueden controlar con precisión su frecuencia cardíaca (FC)mediante la medición manual del pulso. Niños de 9 a 12 años evaluaron manualmente su FC a través del pulso carotídeo tres veces en una sesión deeducación física; tumbados, trasun esfuerzo submáximo y un minuto después. Simultáneamente, se midió la FC mediante pulsómetros. De 417 niños (rango de edad 9 a 12 años, 44,8% niñas), un40% proporcionóvalores precisos (<10% de error). El análisis de concordancia mostró amplios límites de acuerdo (95% de las mediciones situadas entre un 44,76% por debajo y un 78,64% por encima de los valores reales de la FC). El sexo, la edad y el nivel de esfuerzo no tuvieron una influencia significativa en los resultados. Los niños de primaria no son capaces de medir con precisión su FC a través del pulso carotídeo (AU)

Point-of-care ultrasound compression of the carotid artery for pulse determination in cardiopulmonary resuscitation.

AIM: To identify whether a novel pulse check technique, carotid artery compression using an ultrasound probe, can reduce pulse check times compared to manual palpation (MP). METHODS: This prospective study was conducted in an emergency department between February and December 2021. A physician applied point-of-care ultrasound-carotid artery compression (POCUS-CAC) and assessed the carotid artery compressibility and pulsatility by probe compression during rhythm check time. Another clinician performed MP of the femoral artery. The primary outcome was the difference in the average time for pulse assessment between POCUS-CAC and MP. The secondary outcomes included the time difference in each pulse check between methods, the proportion of times greater than 5 s and 10 s, and the prediction of return of spontaneous circulation (ROSC) during ongoing chest compression. RESULTS: 25 cardiac arrest patients and 155 pulse checks were analyzed. The median (interquartile range) average time to carotid pulse identification per patient using POCUS-CAC was 1.62 (1.14-2.14) s compared to 3.50 (2.99-4.99) s with MP. In all 155 pulse checks, the POCUS-CAC time to determine ROSC was significantly shortened to 0.44 times the MP time (P < 0.001). The POCUS-CAC approach never exceeded 10 s, and the number of patients who required more than 5 s was significantly lower (5 vs. 37, P < 0.001). Under continuous chest compression, six pulse checks predicted the ROSC. CONCLUSIONS: We found that emergency physicians could quickly determine pulses by applying simple POCUS compression of the carotid artery in cardiac arrest patients.

Non-Contact Heart Rate Estimation via Adaptive RGB/NIR Signal Fusion.

We propose a non-contact heart rate (HR) estimation method that is robust to various situations, such as bright, low-light, and varying illumination scenes. We utilize a camera that records red, green, and blue (RGB) and near-infrared (NIR) information to capture the subtle skin color changes induced by the cardiac pulse of a person. The key novelty of our method is the adaptive fusion of RGB and NIR signals for HR estimation based on the analysis of background illumination variations. RGB signals are suitable indicators for HR estimation in bright scenes. Conversely, NIR signals are more reliable than RGB signals in scenes with more complex illumination, as they can be captured independently of the changes in background illumination. By measuring the correlations between the lights reflected from the background and facial regions, we adaptively utilize RGB and NIR observations for HR estimation. The experiments demonstrate the effectiveness of the proposed method.

Disclosure of suboptimal health status through traditional Chinese medicine-based body constitution and pulse patterns.

OBJECTIVES: Suboptimal health status (SHS) is a dynamic state wherein people have not been diagnosed with a disease but tend to develop diseases. People with SHS often experience fatigue and other nonspecific symptoms, which are related to a deviated body constitution in traditional Chinese medicine (TCM). However, the correlation between TCM constitution and SHS has not been adequately investigated. Furthermore, no study has explored the radial pulse analysis-an assistive objective indicator of TCM constitution-in healthy people and people with SHS. DESIGN: A cross-sectional study. SETTINGS/LOCATION: Center for Traditional Medicine, Taipei Veterans General Hospital, Taiwan. SUBJECTS: Sixty-six adults (27 healthy participants and 39 participants with SHS) who were aged 20-39 years. OUTCOME MEASURES: The body constitution questionnaire (BCQ) scores, suboptimal health status questionnaire-25 (SHSQ-25) scores, and radial pulse waves detected using sphygmography were recorded. Pulse wave analyses are presented as the ratio of frequency below 10 Hz to that above 10 Hz (SER10), which represent energy changes in organ blood flow. RESULTS: Participants with SHS had significantly higher Yang-Xu, Yin-Xu, and stasis scores of BCQ compared with healthy participants. The SHSQ-25 scores of the participants with SHS were moderately correlated with their Yang-Xu, Yin-Xu, and stasis scores (r = 0.65, 0.66, and 0.72, respectively; all p < 0.001), but weak correlations were discovered for healthy participants. The participants with SHS had significantly higher SER10 at the left guan (the "liver" system in TCM) than did the healthy participants. CONCLUSIONS: SHS is moderately correlated with TCM-based constitution and those with SHS had increased SER10 at the leftguan of the radial pulse.

Flexible Piezoresistive Sensors with Wide-Range Pressure Measurements Based on a Graded Nest-like Architecture.

Flexible pressure sensors present great potential in the application of human health monitoring, tactile function of prosthesis, and electronic skin for robotics. These applications require different trade-off between the sensitivity and sensing range, therefore, it is imperative to develop range-specific sensitivities in a single sensor. In this paper, a bioinspired strategy for a resistive pressure sensor using a graded porous material is proposed to measure pressures from several pascals to megapascals. Its fabrication is based on an easily accessible template method. The nest-architecture-based wide-range pressure sensor exhibits adequate sensitivity under an extensive pressure regime (20 Pa to 1.2 MPa). In addition, with rational structural design and subtle engineering of the material properties, the sensor achieves remarkable mechanical stability. To prove the concept, sensors were attached on a bicycle wheel to monitor the tire-pavement pressure and on human skin to detect biosignals such as venous and arterial blood pressure pulses.

Clinical significance of endothelial vasodilatory function evaluated by EndoPAT in patients with systemic sclerosis.

Endothelial dysfunction is a hallmark of vasculopathy associated with systemic sclerosis (SSc). Reactive hyperemia peripheral arterial tonometry is a rapid and non-invasive technique to assess peripheral microvascular endothelial function by measuring changes in digital pulse volume during reactive hyperemia. Low scores of the reactive hyperemia index (RHI) imply an impaired vasodilatory response and, accordingly, impaired endothelial and vascular health. To investigate the clinical significance of the RHI in SSc patients, RHI values were measured in 43 SSc patients and 10 healthy controls. In diffuse cutaneous SSc (dcSSc) patients, RHI values were significantly decreased compared with healthy controls, and inversely correlated with disease duration. In total SSc patients, there was a significant inverse correlation between RHI values and skin score, and interstitial lung disease was associated with the decrease in RHI values. Among vascular symptoms, the current and past history of digital ulcers was seen more frequently in patients with decreased RHI values than in those with normal RHI values. Although no SSc patients had pulmonary arterial hypertension, an inverse correlation was evident between RHI values and mean pulmonary arterial pressure measured by right heart catheterization. These results indicate that the decrease in RHI values is associated with skin fibrosis, interstitial lung disease, digital ulcers and pulmonary vascular involvement leading to pulmonary arterial hypertension, supporting the canonical idea that endothelial dysfunction is a critical event underlying the development of tissue fibrosis and vascular complications in SSc.

Nurse effects on measurement error in household biosocial surveys.

BACKGROUND: Biosocial survey data are in high demand, yet little is known about the measurement quality of health measures collected by nurses in respondents' homes. Our objective was to analyze the degree to which nurses influence measurement in anthropometric and physical performance indicators collected from respondents in two nationally-representative UK biosocial surveys. METHODS: The English Longitudinal Survey of Ageing and the UK Household Longitudinal Study - Understanding Society were used to analyze fourteen anthropometric and physical performance measures covering weight, height, pulse, grip strength, and lung capacity. Cross-classified multilevel models were used to estimate "nurse effects" on measurement error. RESULTS: Overall, there is a medium effect of nurses on measurement. Across all measures collected in both studies, nurses explain around 13% of all measurement variation. Variation in specific measures range between approximately 2 and 25%. Grip strength and lung capacity are more heavily influenced by nurses than are height, weight, and pulse. Lastly, nurse characteristics explain only a very small proportion of nurse measurement variation. CONCLUSION: Objective health measures collected by nurses in household biosocial surveys are susceptible to non-trivial amounts of measurement variation. Nurse ID numbers should be regularly included in biosocial data releases to allow researchers to account for this unnecessary source of variation. Further, researchers are advised to conduct sensitivity analyses using control variables that account for nurse variation to confirm whether their substantive findings are influenced by nurse measurement effects.

Different Numbers of Long-Pulse 1064-nm Nd-YAG Laser Treatments for Onychomycosis: A Pilot Study.

PURPOSE: To examine the benefits of different numbers of 1064-nm Nd-YAG laser treatments in patients with onychomycosis. METHODS: This was a pilot study of patients with onychomycosis who were divided into three groups: four treatment sessions (group A), eight sessions (group B), and 12 sessions (group C). Only infected nails of degrees II-III (Scoring Clinical Index for Onychomycosis) were included. Treatment was given once a week using a long-pulse Nd-YAG 1064-nm laser. Patients were followed at 8, 16, and 24 weeks after the first treatment. Side effects were recorded. RESULTS: Treatments were completed for 442 nails in 102 patients. The efficacy rates at 8, 16, and 24 weeks were 35.5%, 38.7%, and 37.4% for group A; 31.4%, 41.7%, and 44.0% for group B; and 27.7%, 50.0%, and 55.4% for group C, respectively. There was a significant difference in the efficacy rate at 24 weeks (P = 0.016) between groups A and C, but not for groups A vs. B, or for groups B vs. C. No difference in the efficacy rate at 8 or 16 weeks was observed among the three groups. In all three groups, the efficacy was better for degree II nails than for degree III nails (all P = 0.016) between groups A and C, but not for groups A vs. B, or for groups B vs. C. No difference in the efficacy rate at 8 or 16 weeks was observed among the three groups. In all three groups, the efficacy was better for degree II nails than for degree III nails (all. CONCLUSIONS: The 1064-nm Nd-YAG laser had clinical benefits against onychomycosis. Higher numbers of treatments provided better long-term (24-week) benefits, but had no impact on the short-term outcomes. The efficacy of laser treatment on degree II onychomycosis was better than for degree III.

Non-invasive assessment of arterial pulsatility in patients with continuous-flow left ventricular assist devices.

INTRODUCTION: Long-term use of continuous-flow left ventricular assist devices may have negative consequences for autonomic, cardiovascular and gastrointestinal function. It has thus been suggested that non-invasive monitoring of arterial pulsatility in patients with a left ventricular assist device is highly important for ensuring patient safety and longevity. We have developed a novel, semi-automated frequency-domain-based index of arterial pulsatility that is obtained during suprasystolic occlusions of the upper arm: the 'cuff pulsatility index'. PURPOSE: The purpose of this study was to evaluate the relationship between the cuff pulsatility index and invasively determined arterial pulsatility in patients with a left ventricular assist device. METHODS: Twenty-three patients with a left ventricular assist device with end-stage heart failure (six females: age = 65 ± 9 years; body mass index = 30.5 ± 3.7 kg m-2) were recruited for this study. Suprasystolic occlusions were performed on the upper arm of the patient's dominant side, from which the cuff pressure waveform was obtained. Arterial blood pressure was obtained from the radial artery on the contralateral arm. Measurements were obtained in triplicate. The relationship between the cuff pressure and arterial blood pressure waveforms was assessed in the frequency-domain using coherence analysis. A mixed-effects approach was used to assess the relationship between cuff pulsatility index and invasively determined arterial pulsatility (i.e. pulse pressure). RESULTS: The cuff pressure and arterial blood pressure waveforms demonstrated a high coherence up to the fifth harmonic of the cardiac frequency (heart rate). The cuff pulsatility index accurately tracked changes in arterial pulse pressure within a given patient across repeated measurements. CONCLUSIONS: The cuff pulsatility index shows promise as a non-invasive index for monitoring residual arterial pulsatility in patients with a left ventricular assist device across time.

On detection of spontaneous pulse by photoplethysmography in cardiopulmonary resuscitation.

OBJECTIVE: This work investigates the potential of photoplethysmography (PPG) to detect a spontaneous pulse from the finger, nose or ear in order to support pulse checks during cardiopulmonary resuscitation (CPR). METHODS: In a prospective single-center cross-sectional study, PPG signals were acquired from cardiac arrest victims who underwent CPR. The PPG signals were analyzed and compared to arterial blood pressure (ABP) signals as a reference during three distranaisco; Date: 2/2/2020; Time:18:44:23inct phases of CPR: compression pauses, on-going compressions and at very low arterial blood pressure. Data analysis was based on a qualitative subjective visual description of similarities of the frequency content of PPG and ABP waveform. RESULTS: In 9 patients PPG waveforms corresponded to ABP waveforms during normal blood pressures. During ABP in the clinically challenging range of 60 to 90 mmHg and during chest compressions and pauses, PPG continued to resemble ABP, as both signals showed similar frequency components as a result of chest compressions as well as cardiac activity. Altogether 1199 s of PPG data in compression pauses were expected to show a spontaneous pulse, of which 732 s (61%) of data were artifact-free and showed the spontaneous pulse as visible in the ABP. CONCLUSIONS: PPG signals at all investigated sites can indicate pulse presence at the moment the heart resumes beating as verified via the ABP signal. Therefore, PPG may provide decision support during CPR, especially related to preventing and shortening interruptions for unnecessary pulse checks. This could have impact on CPR outcome and should further be investigated.

Blind Source Separation on Non-Contact Heartbeat Detection by Non-Negative Matrix Factorization Algorithms.

In non-contact heart rate (HR) monitoring via Doppler radar, the disturbance from respiration and/or body motion is treated as a key problem on the estimation of HR. This paper proposes a blind source separation (BSS) approach to mitigate the noise effect in the received radar signal, and incorporates the sparse spectrum reconstruction to achieve a high-resolution of heartbeat spectrum. The proposed BSS decomposes the spectrogram of mixture signal into original sources, including heartbeat, using non-negative matrix factorization (NMF) algorithms, through learning the complete basis spectra (BS) by a hierarchical clustering. In particular, to exploit the temporal sparsity of heartbeat component, two variants of NMF algorithms with sparseness constraints are applied as well, namely sparse NMF and weighted sparse NMF. Compared with usual BSS, our proposed BSS has three advantages: 1) clustering-induced unsupervised manner; 2) compact demixing architecture; and 3) merely requiring single-channel input data. In addition, the HR estimation method using our proposal delivers more satisfactory precision and robustness over other existing methods, which is demonstrated through the measurements of distinguishing people's activities, gaining both smallest absolute errors of HR estimation for sitting still and typewriting.

Acute effects of strength exercise with blood flow restriction on the arterial resistance index / Efeitos agudos do exercício de força com restrição do fluxo sanguíneo sobre o índice de resistência arterial

ABSTRACT The present study aimed to evaluate the acute behavior of the brachial artery resistance index (BARI) and popliteal artery resistance index (PARI) in response to low intensity strength exercises involving small (SMG) and large muscle groups (LMG) performed with and without blood flow restriction. Eleven men (age 23 ± 3.29 years) underwent a four-arm, randomized, cross-over experiment: Small muscle group exercise (SMG), small muscle groups with blood flow restriction (SMG+BFR), large muscle groups (LMG) and large muscle groups with blood flow restriction (LMG+BFR). The behavior of BARI and PARI was evaluated at rest, immediately after exercise, and at 15 and 30 minutes during recovery. Data analysis showed a significant reduction of the BARI from rest to post-exercise only in the protocols involving SMG, regardless of the BFR (p <0.05). Protocols involving LMG, with or without BFR, did not affect PARI (p> 0.05), but were efficient to promote significant increases in BARI (p <0.05) immediately after exercise. Our findings indicate that the exercises involving SMG, regardless of BFR, are efficient to promote local vasodilatation (brachial artery), but without systemic effects. None of the analyzed protocols affected the PARI behavior.

RESUMO O presente estudo objetivou avaliar o comportamento agudo do índice de resistência da artéria braquial (IRAB) e da artéria poplítea (IRAP) em resposta a exercícios de força de baixa intensidade envolvendo pequenos (PGM) e grandes grupos musculares (GGM), realizado com e sem restrição de fluxo sanguíneo. Onze homens (idade 23 ± 3,29 anos) realizaram um experimento randomizado, cruzado, com quatro braços: Exercício para pequenos grupos musculares (PGM), pequenos grupos musculares com restrição de fluxo sanguíneo (PGM+RFS), grandes grupos musculares (GGM) e grandes grupos musculares com restrição de fluxo sanguíneo (GGM+RFS). O comportamento de IRAB e IRAP foi avaliado em repouso, mediatamente após o exercício, e aos 15 e 30 minutos da recuperação. A análise dos dados mostrou uma redução significativa do IRAB do repouso para o pós-exercício apenas nos protocolos de PGM com ou sem RFS (p <0,05). Protocolos envolvendo GGM, independentemente do BFR, não afetaram o IRAP (p> 0,05), porém, foram eficientes para promover aumentos significativos do IRAB (p <0,05) imediatamente após o exercício. Nossos achados indicam que os exercícios envolvendo PGM, independentemente da BFR, são capazes de promover a vasodilatação local (artéria braquial), porém, sem efeitos sistêmicos. Nenhum dos protocolos analisados afetou o comportamento do IRAP.

The POCUS Pulse Check: A Case Series on a Novel Method for Determining the Presence of a Pulse Using Point-of-Care Ultrasound.

BACKGROUND: During cardiopulmonary resuscitation, pulse checks must be rapid and accurate. Despite the importance placed on the detection of a pulse, several studies have shown that health care providers have poor accuracy for detection of central pulses by palpation. To date, the use of point-of-care ultrasound (POCUS) in cardiac arrest has focused on the presence of cardiac standstill and diagnosing reversible causes of the arrest. OBJECTIVE: This case series highlights a simple, novel approach to determine whether pulses are present or absent by using POCUS compression of the central arteries. DISCUSSION: Using this technique, we found that a POCUS pulse check can be consistently performed in < 5 s and is clearly determinate, even when palpation yields indeterminate results. CONCLUSIONS: In this case series, the POCUS pulse check was a valuable adjunct that helped to change management for critically ill patients. Future prospective studies are required to determine the accuracy of this technique and the impact on patient outcomes in a larger cohort.

The POCUS pulse check: A randomized controlled crossover study comparing pulse detection by palpation versus by point-of-care ultrasound.

BACKGROUND: Manual pulse checks (MP) are an unreliable skill even in the hands of healthcare providers (HCPs). In the context of cardiac arrest, this may translate into inappropriate chest compressions when a pulse is present, or conversely omitting chest compressions when one is absent. To date, no study has assessed the use of B-mode ultrasound (US) for the detection of a carotid pulse. The primary objective of this study was to assess the time required to detect a carotid pulse in live subjects using US compared to the traditional palpation method. METHODS: We conducted a prospective randomized controlled crossover non-inferiority trial. HCPs attended a 15 minute focused US workshop on identification of the carotid pulse. Both pulse check methods were timed for each participant on two different subjects in random order. The primary outcome was time to carotid pulse detection in seconds (s). Secondary outcomes included confidence levels of pulse detection measured on a 100 mm visual analog scale (VAS) and rates of prolonged pulse checks (> 5 s or >10 s). The study was powered to determine whether US pulse checks were not slower than MP by greater than two seconds. The results are presented as the difference in means with a 90% two-sided confidence interval (CI). RESULTS: 111 participants completed the study. Mean pulse detection times were 4.22 s (SD 3.26) by US compared to 4.71 s (SD 6.45) by MP with a mean difference in times of -0.49 s (90% CI: -1.77 to 0.39). There were no significant differences between US and MP in the rates of prolonged pulse checks of greater than 5 s (23% vs 19%, p = 0.45) or 10 s (9% vs 8%, p = 0.81). First attempt at detection of pulse checks was more successful in the US group (99.1% vs 85.6%, p = 0.0001). Prior to training, participants reported higher confidence using MP compared to US; 68 (IQR 48-83) vs 15 (IQR 8-42) mm (p < 0.001). Following the study, participants reported higher confidence levels using US than MP; 91 (IQR 82-97) vs 83 (IQR 72-94) mm (p < 0.001). CONCLUSIONS: Carotid pulse detection in live subjects was not slower using US as compared to palpation, and demonstrated higher first attempt success rate and less variability in measurement times. A brief teaching session was sufficient to improve confidence of carotid pulse identification even in those with no previous US training. The preliminary results from this study provide the groundwork for larger studies to evaluate this pulse check method for patients in cardiac arrest.

Can pulse check by the photoplethysmography sensor on a smart watch replace carotid artery palpation during cardiopulmonary resuscitation in cardiac arrest patients? a prospective observational diagnostic accuracy study.

OBJECTIVE: The purpose of this study was to assess whether a photoplethysmography (PPG) sensor in a smart watch can accurately recognise the return of spontaneous circulation (ROSC) in cardiac arrest patients compared with carotid artery palpation. METHODS: This prospective observational study was conducted on 50 out-of-hospital cardiac arrest patients who visited the emergency department (ED) of one tertiary hospital. As soon as the patient arrived at the ED, advanced cardiac life support was carried out immediately. At this time, three smart watches were attached to the carotid artery, forehead and wrist and were checked for pulse measurements every 2 min. In the case of ROSC, blood pressure, heart rate and heart rate regularity were confirmed, and pulse was simultaneously measured at three sites with smart watches. In the case of no ROSC, only the pulse was measured at three sites with the smart watches. RESULTS: There were 33 males (66%) and the mean age was 68±11.57 years. In 14 patients (28%), spontaneous circulation was recovered through cardiopulmonary resuscitation, and all survived. The sensitivity and specificity of manual palpation were 78.6% and 90.4%, respectively. False-positive and false-negative rates were 9.6% and 21.4%, respectively. Smart watches at all three sites had the same or higher sensitivity than manual palpation. The sensitivity of the smart watch was the highest, at 100%, in the carotid region and the lowest, at 78.6%, in the wrist region. The specificity of the smart watch was the highest, at 100%, in the wrist region and the lowest, at 78.7%, in the carotid region. CONCLUSION: Compared with manual pulse check, the PPG sensor embedded in the smart watch showed the same sensitivity and a higher specificity for recognising ROSC when measured at the wrist.

Pulse Arrival Time and Pulse Interval as Accurate Markers to Detect Mechanical Alternans.

Mechanical alternans (MA) is a powerful predictor of adverse prognosis in patients with heart failure and cardiomyopathy, but its use remains limited due to the need of invasive continuous arterial pressure recordings. This study aims to assess novel cardiovascular correlates of MA in the intact human heart to facilitate affordable and non-invasive detection of MA and advance our understanding of the underlying pathophysiology. Arterial pressure, respiration, and ECG were recorded in 12 subjects with healthy ventricles during voluntarily controlled breathing at different respiratory rate, before and after administration of beta-blockers. MA was induced by ventricular pacing. A total of 67 recordings lasting approximately 90 s each were analyzed. Mechanical alternans (MA) was measured in the systolic blood pressure. We studied cardiovascular correlates of MA, including maximum pressure rise during systole (dPdtmax), pulse arrival time (PAT), pulse wave interval (PI), RR interval (RRI), ECG QRS complexes and T-waves. MA was detected in 30% of the analyzed recordings. Beta-blockade significantly reduced MA prevalence (from 50 to 11%, p < 0.05). Binary classification showed that MA was detected by alternans in dPdtmax (100% sens, 96% spec), PAT (100% sens, 81% spec) and PI (80% sens, 81% spec). Alternans in PAT and in PI also showed high degree of temporal synchronization with MA (80 ± 33 and 73 ± 40%, respectively). These data suggest that cardiac contractility is a primary factor in the establishment of MA. Our findings show that MA was highly correlated with invasive measurements of PAT and PI. Since PAT and PI can be estimated using non-invasive technologies, these markers could potentially enable affordable MA detection for risk-prediction.

Monitorización de la variación de la presión de pulso durante la cirugía de resección pulmonar / Monitoring pulse pressure variation during lung resection surgery

Antecedentes y objetivo: La variación de presión de pulso (VPP) es un parámetro dinámico eficaz y ampliamente empleado para predecir el aumento del gasto cardiaco tras la administración de fluidos en cirugía abdominal, sin embargo su uso en cirugía torácica es controvertido. Se diseñó un estudio para describir el comportamiento de la VPP durante cirugía de resección pulmonar. Pacientes y métodos: Estudio observacional prospectivo en pacientes adultos programados para cirugía de resección pulmonar. Se excluyeron los pacientes con sangrado mayor de 200cc o con necesidad de vasopresores durante la recogida de datos. Se recogieron los valores de la VPP durante diferentes fases: en ventilación bipulmonar (T1), tras el inicio de la ventilación unipulmonar y la apertura del tórax (T2), al finalizar el procedimiento previo a la reinstauración de la ventilación bipulmonar (T3) y tras el cierre del tórax en ventilación bipulmonar (T4). Se calculó el coeficiente de correlación de los valores de VPP en los diferentes momentos. Resultados: Se incluyeron 50 pacientes consecutivos. Los valores medios y desviaciones estándar de VPP en las diferentes fases fueron: T1: 11,14% (6,67); T2: 6,24% (3,21; T3: 5,68% (3,19) y T4: 7,84% (4,61). El ANOVA de medidas repetidas encontró diferencias significativas entre los valores medios de VPP en las diferentes fases (p <0,001). La correlación entre los valores de VPP durante T1 y T2 (VPPT1 y VPPT2) fue de r = 0,868 ([p <0,001], r2 = 0,753), mientras que entre T3 y T4 (VPPT3 y VPPT4) la correlación fue de r=0,616 ([p <0,001], r2=0,379) entre los valores de VPP en T3 y T4. Conclusiones: La VPP presenta un comportamiento predecible en el transcurso de cirugía de resección pulmonar, caracterizado por una disminución de casi el 50% al inicio de la ventilación unipulmonar y apertura del tórax y posteriormente se mantiene estable a lo largo de la cirugía cuando no hay cambios en la volemia

Background and objective: Although pulse pressure variation (PPV) is an effective dynamic parameter widely used to predict the increase in cardiac output after the administration of fluids in abdominal surgery, its use in thoracic surgery is controversial. A study was designed to describe the behaviour of PPV during lung resection surgery. Patients and methods: A prospective observational study was conducted on adult patients scheduled for lung resection surgery. Patients with bleeding greater than 200cc, or those who required vasopressors during data collection, were excluded. The PPV values were collected during different phases: in bipulmonary ventilation (T1), after the start of single lung ventilation, and the opening of the thorax (T2), at the end of the procedure prior to the restoration of the bipulmonary ventilation (T3), and after the closure of the thorax in bipulmonary ventilation (T4). The correlation coefficient of the PPV values at the different times was calculated. Results: The study included 50 consecutive patients. The mean values and standard deviations of PPV in the different phases were: T1, 11.14% (6.67); T2 6.24% (3.21, T3 5.68% (3.19), and T4 7.84% (4.61). The repeated ANOVA measurements found significant differences between the mean values of PPV in the different phases (P<.001). The correlation between the PPV values during T1 and T2 (PPVT1 and PPVT2) was r=0.868 ([P<.001], r2=0.753), while between T3 and T4 (PPVT3 and PPVT4) the correlation was r=0.616 ([P<.001], r2=0.379) between the PPV values in T3 and T4. Conclusions: PPV presents a predictable behaviour in the course of lung resection surgery, characterised by a decrease of almost half at the beginning of the unipulmonary ventilation and opening of the thorax. It then remains stable throughout the surgery when there are no changes in the intravascular blood volume

Comparison of pulse contour, aortic Doppler ultrasound and bioelectrical impedance estimates of stroke volume during rapid changes in blood pressure.

NEW FINDINGS: What is the central question of this study? Pulse contour analysis of the finger arterial pressure by Windkessel modelling is commonly used to estimate stroke volume continuously. But is it valid during dynamic changes in blood pressure? What is the main finding and its importance? Second-by-second analysis revealed that pulse contour analysis underestimated stroke volume by up to 25% after standing from a squat, and 16% after standing thigh-cuff release, when compared with aortic Doppler ultrasound estimates. These results reveal that pulse contour analysis of stroke volume should be interpreted with caution during rapid changes in physiological state. ABSTRACT: Dynamic measurements of stroke volume (SV) and cardiac output provide an index of central haemodynamics during transitional states, such as postural changes and onset of exercise. The most widely used method to assess dynamic fluctuations in SV is the Modelflow method, which uses the arterial blood pressure waveform along with age- and sex-specific aortic properties to compute beat-to-beat estimates of aortic flow. Modelflow has been validated against more direct methods in steady-state conditions, but not during dynamic changes in physiological state, such as active orthostatic stress testing. In the present study, we compared the dynamic SV responses from Modelflow (SVMF ), aortic Doppler ultrasound (SVU/S ) and bioelectrical impedance analysis (SVBIA ) during two different orthostatic stress tests, a squat-to-stand (S-S) transition and a standing bilateral thigh-cuff release (TCR), in 15 adults (six females). Second-by-second analysis revealed that when compared with estimates of SV by aortic Doppler ultrasound, Modelflow underestimated SV by up to 25% from 3 to 11 s after standing from the squat position and by up to 16% from 3 to 7 s after TCR (P < 0.05). The SVMF and SVBIA were similar during the first minute of the S-S transition, but were different 3 s after TCR and at intermittent time points between 34 and 44 s (P < 0.05). These findings indicate that the physiological conditions elicited by orthostatic stress testing violate some of the inherent assumptions of Modelflow and challenge models used to interpret bioelectrical impedance responses, resulting in an underestimation in SV during rapid changes in physiological state.

A Stochastic Gradient Approach for Robust Heartbeat Detection With Doppler Radar Using Time-Window-Variation Technique.

Heart rate (HR) variability indicates health condition and mental stress. The development of non-contact HR monitoring techniques with Doppler radar is attracting great attention. However, the performance of heartbeat detection via radar signals easily degrades due to respiration and body motion. In this paper, first, a stochastic gradient approach is applied to reconstruct the high-resolution spectrum of heartbeat by proposing the zero-attracting sign least-mean-square (ZA-SLMS) algorithm. To correct the quantized gradient of cost function and penalize the sparse constraint on updating the spectrum, a more accurate heartbeat spectrum is reconstructed. Then, to better adapt to the noises of different strengths caused by subjects' movements, an adaptive regularization parameter is introduced in the ZA-SLMS algorithm as an improved variant, which can adaptively regulate the proportion between gradient correction and sparse penalty. Moreover, in view of the stability of the location of the spectral peak associated with the HR when the size of time window slightly changes, a time-window-variation (TWV) technique is further incorporated in the improved ZA-SLMS (IZA-SLMS) algorithm for more stable HR estimation. Through the experiments on five subjects, our proposal is demonstrated to bring a significant improvement in accuracy compared with existing detection methods. Specifically, the IZA-SLMS algorithm with TWV achieves the smallest average error of 3.79 beats per minute when subjects type on a laptop.

Analysis of Pulse Signals Based on Array Pulse Volume.

OBJECTIVE: To collect and analyze multi-dimensional pulse diagram features with the array sensor of a pressure profile system (PPS) and study the characteristic parameters of the new multi-dimensional pulse diagram by pulse diagram analysis technology. METHODS: The pulse signals at the Guan position of left wrist were acquired from 105 volunteers at the Shanghai University of Traditional Chinese Medicine. We obtained the pulse data using an array sensor with 3×4 channels. Three dimensional pulse diagrams were constructed for the validated pulse data, and the array pulse volume (APV) parameter was computed by a linear interpolation algorithm. The APV differences among normal pulse (NP), wiry pulse (WP) and slippery pulse (SP) were analyzed using one-way analysis of variance. The coefficients of variation (CV) were calculated for WP, SP and NP. RESULTS: The APV difference between WP and NP in the 105 volunteers was statistically significant (6.26±0.28 vs. 6.04±0.36, P=0.048), as well as the difference between WP and SP (6.26±0.28 vs. 6.07±0.46, P=0.049). However, no statistically significant difference was found between NP and SP (P=0.75). WP showed a similar CV (4.47%) to those of NP (5.96%) and SP (7.58%). CONCLUSION: The new parameter APV could differentiate between NP or SP and WP. Accordingly, APV could be considered an useful parameter for the analysis of array pulse diagrams in Chinese medicine.