Clinical review: a review and analysis of heart rate variability and the diagnosis and prognosis of infection

Applying Artificial Intelligence to Identify Physiomarkers Predicting Severe Sepsis in the PICU

OBJECTIVES

We used artificial intelligence to develop a novel algorithm using physiomarkers to predict the onset of severe sepsis in critically ill children.

DESIGN

Observational cohort study.

SETTING

PICU.

PATIENTS

Children age between 6 and 18 years old.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Continuous minute-by-minute physiologic data were available for a total of 493 critically ill children admitted to a tertiary care PICU over an 8-month period, 20 of whom developed severe sepsis. Using an alert time stamp generated by an electronic screening algorithm as a reference point, we studied up to 24 prior hours of continuous physiologic data. We identified physiomarkers, including SD of heart rate, systolic and diastolic blood pressure, and symbolic transitions probabilities of those variables that discriminated severe sepsis patients from controls (all other patients admitted to the PICU who did not meet severe sepsis criteria). We used logistic regression, random forests, and deep Convolutional Neural Network methods to derive our models. Analysis was performed using data generated in two windows prior to the firing of the electronic screening algorithm, namely, 2-8 and 8-24 hours. When analyzing the physiomarkers present in the 2-8 hours analysis window, logistic regression performed with specificity of 87.4% and sensitivity of 55.0%, random forest performed with 79.6% specificity and 80.0% sensitivity, and the Convolutional Neural Network performed with 83.0% specificity and 75.0% sensitivity. When analyzing physiomarkers from the 8-24 hours window, logistic regression resulted in 77.1% specificity and 39.3% sensitivity, random forest performed with 82.3% specificity and 61.1% sensitivity, whereas the Convolutional Neural Network method achieved 81% specificity and 76% sensitivity.

CONCLUSIONS

Artificial intelligence can be used to predict the onset of severe sepsis using physiomarkers in critically ill children. Further, it may detect severe sepsis as early as 8 hours prior to a real-time electronic severe sepsis screening algorithm.

Effects of esmolol on systemic hemodynamics and heart rate variability measured using the Analgesia/Nociception Index in resuscitated piglets with Pseudomonas aeruginosa septic shock

OBJECTIVE

To determine the effects of esmolol on hemodynamics and heart rate variability (HRV) in the early stage of sepsis.

DESIGN

Prospective, randomized, controlled, parallel trial.

SETTINGS

Veterinary research laboratory.

ANIMALS

Ten anesthetized piglets.

INTERVENTIONS

Septic shock was induced by infusing a suspension of live Pseudomonas aeruginosa IV in 10 anesthetized piglets. The piglets were resuscitated according to a standardized protocol using Ringer's lactate solution, norepinephrine, and milrinone. Once stabilized, the piglets were randomized to receive IV esmolol, titrated to a heart rate <90/min, or control, receiving saline. A pulmonary artery catheter and an arterial catheter were inserted for hemodynamic measurements. The Analgesia/Nociception Index (ANI) and the normalized HRV frequency domain parameters - high-frequency (HF), low frequency (LF), LF/HF ratio - were recorded using a proprietary monitor.

MEASUREMENTS AND MAIN RESULTS

A significant decrease in cardiac output and heart rate, and a significant increase in systemic vascular resistance were observed over time in the esmolol group in comparison to the control group. No other differences were observed in hemodynamic parameters. No significant differences were observed in ANI variations or HRV parameters over time between groups.

CONCLUSIONS

The administration of esmolol produced significant changes in hemodynamics with no change in ANI values or HRV parameters. Further study is needed to understand the effect of esmolol during sepsis.

Reducing Psychological Stress in Peripartum Women With Heart Rate Variability Biofeedback: A Systematic Review

Peripartum women are exposed to a variety of stressors that have adverse health consequences for the maternal-child dyad (e.g., impaired bonding). To combat these adverse health consequences, heart rate variability biofeedback (HRVBF) may be implemented by holistic nurses to aid peripartum women experiencing a high level of stress. A systematic review was completed using the guidelines established in the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. To be included in the review, studies had to meet the following criteria: (a) published scientific articles, (b) studies published in English, (c) experimental, quasi-experimental, or case reports, (d) use of HRVBF as the main treatment, (e) use of psychological stress as a dependent variable, and (f) studies published until December 2017. The major findings of this review can be described as follows: (a) HRVBF and psychological stress in peripartum women are related concepts, (b) peripartum women who completed HRVBF report a reduction in stress compared with participants who did not receive HRVBF, and (c) there is currently no information on the effectiveness of HRVBF on psychological stress in the first and early second trimester of pregnancy. Overall, this systematic review of the literature provides objective evidence that HRVBF may be a potential beneficial adjuvant treatment for stress management in peripartum women.

American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Septic Shock

OBJECTIVES

The American College of Critical Care Medicine provided 2002 and 2007 guidelines for hemodynamic support of newborn and pediatric septic shock. Provide the 2014 update of the 2007 American College of Critical Care Medicine "Clinical Guidelines for Hemodynamic Support of Neonates and Children with Septic Shock."

DESIGN

Society of Critical Care Medicine members were identified from general solicitation at Society of Critical Care Medicine Educational and Scientific Symposia (2006-2014). The PubMed/Medline/Embase literature (2006-14) was searched by the Society of Critical Care Medicine librarian using the keywords: sepsis, septicemia, septic shock, endotoxemia, persistent pulmonary hypertension, nitric oxide, extracorporeal membrane oxygenation, and American College of Critical Care Medicine guidelines in the newborn and pediatric age groups.

MEASUREMENTS AND MAIN RESULTS

The 2002 and 2007 guidelines were widely disseminated, translated into Spanish and Portuguese, and incorporated into Society of Critical Care Medicine and American Heart Association/Pediatric Advanced Life Support sanctioned recommendations. The review of new literature highlights two tertiary pediatric centers that implemented quality improvement initiatives to improve early septic shock recognition and first-hour compliance to these guidelines. Improved compliance reduced hospital mortality from 4% to 2%. Analysis of Global Sepsis Initiative data in resource rich developed and developing nations further showed improved hospital mortality with compliance to first-hour and stabilization guideline recommendations.

CONCLUSIONS

The major new recommendation in the 2014 update is consideration of institution-specific use of 1) a "recognition bundle" containing a trigger tool for rapid identification of patients with septic shock, 2) a "resuscitation and stabilization bundle" to help adherence to best practice principles, and 3) a "performance bundle" to identify and overcome perceived barriers to the pursuit of best practice principles.

Heart rate variability in critical care medicine: a systematic review

BACKGROUND

Heart rate variability (HRV) has been used to assess cardiac autonomic activity in critically ill patients, driven by translational and biomarker research agendas. Several clinical and technical factors can interfere with the measurement and/or interpretation of HRV. We systematically evaluated how HRV parameters are acquired/processed in critical care medicine.

METHODS

PubMed, MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (1996-2016) were searched for cohort or case-control clinical studies of adult (>18 years) critically ill patients using heart variability analysis. Duplicate independent review and data abstraction. Study quality was assessed using two independent approaches: Newcastle-Ottowa scale and Downs and Black instrument. Conduct of studies was assessed in three categories: (1) study design and objectives, (2) procedures for measurement, processing and reporting of HRV, and (3) reporting of relevant confounding factors.

RESULTS

Our search identified 31/271 eligible studies that enrolled 2090 critically ill patients. A minority of studies (15; 48%) reported both frequency and time domain HRV data, with non-normally distributed, wide ranges of values that were indistinguishable from other (non-critically ill) disease states. Significant heterogeneity in HRV measurement protocols was observed between studies; lack of adjustment for various confounders known to affect cardiac autonomic regulation was common. Comparator groups were often omitted (n = 12; 39%). This precluded meaningful meta-analysis.

CONCLUSIONS

Marked differences in methodology prevent meaningful comparisons of HRV parameters between studies. A standardised set of consensus criteria relevant to critical care medicine are required to exploit advances in translational autonomic physiology.

Systems Biology and Clinical Practice in Respiratory Medicine. The Twain Shall Meet

Respiratory diseases are highly complex, being driven by host-environment interactions and manifested by inflammatory, structural, and functional abnormalities that vary over time. Traditional reductionist approaches have contributed vastly to our knowledge of biological systems in health and disease to date; however, they are insufficient to provide an understanding of the behavior of the system as a whole. In this Pulmonary Perspective, we discuss systems biology approaches, especially but not limited to the study of the lung as a complex system. Such integrative approaches take into account the large number of dynamic subunits and their interactions found in biological systems. Borrowing methods from physics and mathematics, it is possible to study the collective behavior of these systems over time and in a multidimensional manner. We first examine the physiological basis for complexity in the respiratory system and its implications for disease. We then expand on the potential applications of systems biology methods to study complex systems, within the context of diagnosis and monitoring of respiratory diseases including asthma, chronic obstructive pulmonary disease (COPD), and critical illness. We summarize the significant advances made in recent years using systems approaches for disease phenotyping, applied to data ranging from the molecular to clinical level, obtained from large-scale asthma and COPD networks. We describe new studies using temporal complexity patterns to characterize asthma and COPD and predict exacerbations as well as predict adverse outcomes in critical care. We highlight new methods that are emerging with this approach and discuss remaining questions that merit greater attention in the field.

Advanced Materials for Health Monitoring with Skin-Based Wearable Devices

Skin-based wearable devices have a great potential that could result in a revolutionary approach to health monitoring and diagnosing disease. With continued innovation and intensive attention to the materials and fabrication technologies, development of these healthcare devices is progressively encouraged. This article gives a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to recent advances and developments in the scope of skin-based wearable devices (e.g. temperature, strain, biomarker-analysis werable devices, etc.), with an emphasis on emerging materials and fabrication techniques in the relevant fields. To give a comprehensive statement, part of the review presents and discusses different aspects of these advanced materials, such as the sensitivity, biocompatibility and durability as well as the major approaches proposed for enhancing their chemical and physical properties. A complementary section of the review linking these advanced materials with wearable device technologies is particularly specified. Some of the strong and weak points in development of each wearable material/device are highlighted and criticized. Several ideas regarding further improvement of skin-based wearable devices are also discussed.

Influence diagram of physiological and environmental factors affecting heart rate variability: an extended literature overview

Heart rate variability (HRV) corresponds to the adaptation of the heart to any stimulus. In fact, among the pathologies affecting HRV the most, there are the cardiovascular diseases and depressive disorders, which are associated with high medical cost in Western societies. Consequently, HRV is now widely used as an index of health.

In order to better understand how this adaptation takes place, it is necessary to examine which factors directly influence HRV, whether they have a physiological or environmental origin. The primary objective of this research is therefore to conduct a literature review in order to get a comprehensive overview of the subject.

The system of these factors affecting HRV can be divided into the following five categories: physiological and pathological factors, environmental factors, lifestyle factors, non-modifiable factors and effects. The direct interrelationships between these factors and HRV can be regrouped into an influence diagram. This diagram can therefore serve as a basis to improve daily clinical practice as well as help design even more precise research protocols.

Respiratory rate and pulse oximetry derived information as predictors of hospital admission in young children in Bangladesh: a prospective observational study

OBJECTIVE

Hypoxaemia is a strong predictor of mortality in children. Early detection of deteriorating condition is vital to timely intervention. We hypothesise that measures of pulse oximetry dynamics may identify children requiring hospitalisation. Our aim was to develop a predictive tool using only objective data derived from pulse oximetry and observed respiratory rate to identify children at increased risk of hospital admission.

SETTING

Tertiary-level hospital emergency department in Bangladesh.

PARTICIPANTS

Children under 5 years (n=3374) presenting at the facility (October 2012-April 2013) without documented chronic diseases were recruited. 1-minute segments of pulse oximetry (photoplethysmogram (PPG), blood oxygen saturation (SpO2) and heart rate (HR)) and respiratory rate were collected with a mobile app.

PRIMARY OUTCOME

The need for hospitalisation based on expert physician review and follow-up.

METHODS

Pulse rate variability (PRV) using pulse peak intervals of the PPG signal and features extracted from the SpO2 signal, all derived from pulse oximetry recordings, were studied. A univariate age-adjusted logistic regression was applied to evaluate differences between admitted and non-admitted children. A multivariate logistic regression model was developed using a stepwise selection of predictors and was internally validated using bootstrapping.

RESULTS

Children admitted to hospital showed significantly (p<0.01) decreased PRV and higher SpO2 variability compared to non-admitted children. The strongest predictors of hospitalisation were reduced PRV-power in the low frequency band (OR associated with a 0.01 unit increase, 0.93; 95% CI 0.89 to 0.98), greater time spent below an SpO2 of 98% and 94% (OR associated with 10 s increase, 1.4; 95% CI 1.3 to 1.4 and 1.5; 95% CI 1.4 to 1.6, respectively), high respiratory rate, high HR, low SpO2, young age and male sex. These variables provided a bootstrap-corrected AUC of the receiver operating characteristic of 0.76.

CONCLUSIONS

Objective measurements, easily obtained using a mobile device in low-resource settings, can predict the need for hospitalisation. External validation will be required before clinical adoption.

Brazilian studies on pulmonary function in COPD patients: what are the gaps?

BACKGROUND

COPD is a major cause of death and morbidity worldwide, and is characterized by persistent airflow obstruction. The evaluation of obstruction is critically dependent on sensitive methods for lung-function testing. A wide body of knowledge has been accumulated in recent years showing that these methods have been significantly refined and seems promising for detection of early disease.

OBJECTIVES

This review focuses on research on pulmonary function analysis in COPD performed in Brazil during this century.

MATERIALS AND METHODS

The literature was searched using a systematic search strategy limited to English language studies that were carried out in Brazil from the year 2000 onward, with study objectives that included a focus on lung function.

RESULTS

After we applied our inclusion and exclusion criteria, 94 articles addressed our stated objectives. Among the new methods reviewed are the forced-oscillation technique and the nitrogen-washout test, which may provide information on small-airway abnormalities. Studies investigating the respiratory muscles and thoracoabdominal motion are also discussed, as well as studies on automatic clinical decision-support systems and complexity measurements. We also examined important gaps in the present knowledge and suggested future directions for the cited research fields.

CONCLUSION

There is clear evidence that improvements in lung-function methods allowed us to obtain new pathophysiological information, contributing to improvement in our understanding of COPD. In addition, they may also assist in the diagnosis and prevention of COPD. Further investigations using prospective and longitudinal design may be of interest to elucidate the use of these new methods in the diagnosis and prevention of COPD.

Heart rate time series characteristics for early detection of infections in critically ill patients

It is difficult to make a distinction between inflammation and infection. Therefore, new strategies are required to allow accurate detection of infection. Here, we hypothesize that we can distinguish infected from non-infected ICU patients based on dynamic features of serum cytokine concentrations and heart rate time series. Serum cytokine profiles and heart rate time series of 39 patients were available for this study. The serum concentration of ten cytokines were measured using blood sampled every 10 min between 2100 and 0600 hours. Heart rate was recorded every minute. Ten metrics were used to extract features from these time series to obtain an accurate classification of infected patients. The predictive power of the metrics derived from the heart rate time series was investigated using decision tree analysis. Finally, logistic regression methods were used to examine whether classification performance improved with inclusion of features derived from the cytokine time series. The AUC of a decision tree based on two heart rate features was 0.88. The model had good calibration with 0.09 Hosmer-Lemeshow p value. There was no significant additional value of adding static cytokine levels or cytokine time series information to the generated decision tree model. The results suggest that heart rate is a better marker for infection than information captured by cytokine time series when the exact stage of infection is not known. The predictive value of (expensive) biomarkers should always be weighed against the routinely monitored data, and such biomarkers have to demonstrate added value.

Heart rate variability is reduced during acute uncomplicated diverticulitis

BACKGROUND

The aim of the present study was to report the trajectory of heart rate variability (HRV) indices during a low-grade acute inflammation and their associations to biomarkers for infection.

METHODS

Twelve patients with uncomplicated acute diverticulitis completed this observational study, which composed of 3 sessions of continuous HRV recording from 9 PM to 8 AM during ongoing diverticulitis and at complete remission (baseline). The blood samples were collected at each study session measuring C-reactive protein (CRP) and leukocytes.

RESULTS

This study showed that the trajectories of the HRV indices were decreased both in time and frequency domains during acute diverticulitis compared to baseline. In particular, the indices reflecting the balance of sympathetic and parasympathetic activities were affected: standard deviation of normal-to-normal beats (P = .003), low-frequency power (P < .001), and total power (P = .001). These HRV changes indicate alterations in the autonomic nervous system during acute inflammation. All reductions of mean HRV indices had significant (P < .001) correlations to increased CRP correlations to increased CRP levels during diverticulitis suggesting inflammatory involvement in the observed HRV alterations.

CONCLUSION

We found substantial HRV depression in relation to acute uncomplicated diverticulitis, and this was associated with the elevated CRP levels.

The Baroreflex Mechanism Revisited

We state that the autonomic part of the brain controls the blood pressure (BP) and the heart rate (HR) via the baroreflex mechanism in all situations of human activity (at sleep, at rest, during exercise, fright etc.), in a way which is not, as was hitherto assumed, a mere homeostatic tool or even a resetting device, designed to bring these variables on the road to preset values. The baroreflex is rather a continuous feedback mechanism commanded by the autonomic part of the brain, leading to values appropriate to the situation at hand. Feasibility of this assertion is demonstrated here by using the Seidel-Herzel feedback system outside of its regular practice. Results show indeed that the brain can, and we claim that it does, control the HR and BP throughout life. New responses are demonstrated, e.g., to a sudden fear or apnea. In this event, large BP and HR overshoots are expected before the variables can relax to a new level. Response to abrupt downward change in the controlling parameter shows an undershoot in HR and just a gradual resetting in the BP. The relaxation from sudden external changes to various expected states are calculated and discussed and properties of the Rheos test are explained. Experimental findings for orthostatic tests and for babies under translations and rotations reveal complete qualitative agreement with our model and show no need to invoke the operation of additional body systems. Our method should be the preferred one by the Occam Razor approach. The outcomes may lead to beneficial clinical implication.

Spontaneous breathing trial in T-tube negatively impact on autonomic modulation of heart rate compared with pressure support in critically ill patients

INTRODUCTION

Spontaneous breathing with a conventional T-piece (TT) connected to the tracheal tube orotraqueal has been frequently used in clinical setting to weaning of mechanical ventilation (MV), when compared with pressure support ventilation (PSV). However, the acute effects of spontaneous breathing with TT versus PSV on autonomic function assessed through heart rate variability (HRV) have not been fully elucidated.

OBJECTIVE

The purpose of this study was to examine the acute effects of spontaneous breathing in TT vs PSV in critically ill patients.

METHOD

Twenty-one patients who had received MV for ≥ 48 h and who met the study inclusion criteria for weaning were assessed. Eligible patients were randomized to TT and PSV. Cardiorespiratory responses (respiratory rate -ƒ, tidal volume-V_T , mean blood pressure (MBP) and diastolic blood pressure (DBP), end tidal dioxide carbone (P_ET CO₂ ), peripheral oxygen saturation (SpO₂ ) and HRV indices in frequency domain (low-LF, high frequency (HF) and LF/HF ratio were evaluated.

RESULTS

TT increased ƒ (20 ± 5 vs 25 ± 4 breaths/min, P<0.05), MBP (90 ± 14 vs 94 ± 18 mmHg, P<0.05), HR (90 ± 17 vs 96 ± 12 beats/min, P<0.05), P_ET CO₂ (33 ± 8 vs 48 ± 10 mmHg, P<0.05) and reduced SpO₂ (98 ± 1.6 vs 96 ± 1.6%, P<0.05). In addition, LF increased (47 ± 18 vs 38 ± 12 nu, P<0.05) and HF reduced (29 ± 13 vs 32 ± 16 nu, P<0.05), resulting in higher LF/HF ratio (1.62 ± 2 vs 1.18 ± 1, P<0.05) during TT. Conversely, V_T increased with PSV (0.58 ± 0.16 vs 0.50 ± 0.15 L, P<0.05) compared with TT.

CONCLUSION

Acute effects of TT mode may be closely linked to cardiorespiratory mismatches and cardiac autonomic imbalance in critically ill patients.

Impaired heart rate regulation and depression of cardiac chronotropic and dromotropic function in polymicrobial sepsis

The scope of cardiac pathophysiology in sepsis has not been fully defined. Accordingly, we evaluated the effects of sepsis on heart rate (HR), HR variability, and conduction parameters in a murine model of sepsis. Electrocardiograms were recorded noninvasively from conscious mice before and after cecal ligation and puncture (CLP) or sham surgery. Responses of isolated atria to tyramine and isoproterenol were quantified to assess the functional state of sympathetic nerves and postjunctional sensitivity to adrenergic stimulation. Cecal ligation and puncture mice had lower HR compared with sham at 16 to 18 h postsurgery (sham, 741 ± 7 beats/min; CLP, 557 ± 31 beats/min; n = 6/group; P < 0.001), and there was significant prolongation of the PR, QRS, and QTc intervals. Slowing of HR and conduction developed within 4 to 6 h after CLP and were preceded by a decrease in HR variability. Treatment of CLP mice with isoproterenol (5 mg/kg, intraperitoneally) at 25 h after surgery failed to increase HR or decrease conduction intervals. The lack of in vivo response to isoproterenol cannot be attributed to hypothermia because robust chronotropic and inotropic responses to isoproterenol were evoked from isolated atria at 25 °C and 30 °C. These findings demonstrate that impaired regulation of HR (i.e., reduced HR variability) develops before the onset of overt cardiac rate and conduction changes in septic mice. Subsequent time-dependent decreases in HR and cardiac conduction can be attributed to hypothermia and would contribute to decreased cardiac output and organ perfusion. Because isolated atria from septic mice showed normal responsiveness to adrenergic stimulation, we conclude that impaired effectiveness of isoproterenol in vivo can be attributed to reversible effects of systemic factors on adrenergic receptors and/or postreceptor signaling.

Physiologic variability at the verge of systemic inflammation: multiscale entropy of heart rate variability is affected by very low doses of endotoxin

INTRODUCTION

Human injury or infection induces systemic inflammation with characteristic neuroendocrine responses. Fluctuations in autonomic function during inflammation are reflected by beat-to-beat variation in heart rate, termed heart rate variability (HRV). In the present study, we determine threshold doses of endotoxin needed to induce observable changes in markers of systemic inflammation, investigate whether metrics of HRV exhibit a differing threshold dose from other inflammatory markers, and investigate the size of data sets required for meaningful use of multiscale entropy (MSE) analysis of HRV.

METHODS

Healthy human volunteers (n = 25) were randomized to receive placebo (normal saline) or endotoxin/lipopolysaccharide (LPS): 0.1, 0.25, 0.5, 1.0, or 2.0 ng/kg administered intravenously. Vital signs were recorded every 30 min for 6 h and then at 9, 12, and 24 h after LPS. Blood samples were drawn at specific time points for cytokine measurements. Heart rate variability analysis was performed using electrocardiogram epochs of 5 min. Multiscale entropy for HRV was calculated for all dose groups to scale factor 40.

RESULTS

The lowest significant threshold dose was noted in core temperature at 0.25 ng/kg. Endogenous tumor necrosis factor α and interleukin 6 were significantly responsive at the next dosage level (0.5 ng/kg) along with elevations in circulating leukocytes and heart rate. Responses were exaggerated at higher doses (1 and 2 ng/kg). Time domain and frequency domain HRV metrics similarly suggested a threshold dose, differing from placebo at 1.0 and 2.0 ng/kg, below which no clear pattern in response was evident. By applying repeated-measures analysis of variance across scale factors, a significant decrease in MSE was seen at 1.0 and 2.0 ng/kg by 2 h after exposure to LPS. Although not statistically significant below 1.0 ng/kg, MSE unexpectedly decreased across all groups in an orderly dose-response pattern not seen in the other outcomes.

CONCLUSIONS

By using repeated-measures analysis of variance across scale factors, MSE can detect autonomic change after LPS challenge in a group of 25 subjects using electrocardiogram epochs of only 5 min and entropy analysis to scale factor of only 40, potentially facilitating MSE's wider use as a research tool or bedside monitor. Traditional markers of inflammation generally exhibit threshold dose behavior. In contrast, MSE's apparent continuous dose-response pattern, although not statistically verifiable in this study, suggests a potential subclinical harbinger of infectious or other insult. The possible derangement of autonomic complexity prior to or independent of the cytokine surge cannot be ruled out. Future investigation should focus on confirmation of overt inflammation following observed decreases in MSE in a clinical setting.

Improved Effect of Continuous Renal Replacement Therapy in Metabolic Status and Body Composition of Early Phase of Acute Pancreatitis

Objective

To observe the metabolic changes in the early phase of acute pancreatitis (AP) patients induced by continuous renal replacement therapy (CRRT), and to investigate the correlation between the metabolic changes and outcomes of the AP patients.

Methods

We performed a retrospective analysis in the surgical intensive care unit (ICU) of a tertiary teaching hospital. A total of 169 patients diagnosed as AP were divided into 2 groups: CRRT group (n = 71) and non-CRRT group (n = 98), based on whether they received CRRT for more than 24 hours within 7 days from onset of AP. Measured energy expenditure was measured by indirect calorimetry and predicted energy expenditure was determined by specific equations on admission and day 7 (or the closest day to day 7), respectively. Meanwhile, the body composition was measured by multiple-frequency bioelectrical impedance analyzer. Blood test, body weight and vital signs were analyzed daily for both groups.

Results

In this study, we found a significant improvement in the hypermetabolism and fluid distribution of the CRRT group compared with the non-CRRT group. Complications, hospital and ICU length of stays were reduced in CRRT patients.

Conclusions

CRRT is an effective treatment for AP patients. Patients with overhydration and hypermetabolism may get improved outcomes from CRRT.

Role of heart rate variability in predicting the severity of severe acute pancreatitis

BACKGROUND

Infected pancreatic necrosis (IPN) and multiple organ dysfunction syndrome (MODS) are major complications of acute pancreatitis which determine disease severity and outcome.

AIMS

The aim of this study is to investigate the value of admission heart rate variability as a marker of IPN or MODS in severe acute pancreatitis (SAP) patients.

METHODS

Forty-one SAP patients within 72 h of symptoms onset were included in this prospective observational study. General demographics, laboratory data and the acute physiology and chronic health evaluation (APACHE) II scores were recorded at admission. 5-minute ECG signals were obtained at the same time for heart rate variability analyses to assess SAP severity.

RESULTS

The baseline heart rate variability measurements, levels of low frequency/high frequency (LF/HF) were significantly lower whereas high frequency norm (nHF) levels were significantly higher in patients who present with IPN and MODS or died (P < 0.01). Low frequency (LF) levels were lower in patients who present with IPN or MODS as compared to patients without these complications. Levels of low frequency norm (nLF) were lower in MODS and non-survival patients. nHF and LF/HF were good predictors of IPN and MODS, superior to procalcitonin. nHF and LF/HF were better than APACHE II in predicting IPN and LF/HF showed superiority over APACHE II in the prediction of MODS.

CONCLUSIONS

Admission heart rate variability is a good marker of IPN and MODS in SAP patients.

Heart rate variability biofeedback: how and why does it work?

In recent years there has been substantial support for heart rate variability biofeedback (HRVB) as a treatment for a variety of disorders and for performance enhancement (Gevirtz, 2013). Since conditions as widely varied as asthma and depression seem to respond to this form of cardiorespiratory feedback training, the issue of possible mechanisms becomes more salient. The most supported possible mechanism is the strengthening of homeostasis in the baroreceptor (Vaschillo et al., 2002; Lehrer et al., 2003). Recently, the effect on the vagal afferent pathway to the frontal cortical areas has been proposed. In this article, we review these and other possible mechanisms that might explain the positive effects of HRVB.

Sepsis: current dogma and new perspectives

Sepsis, a clinical syndrome occurring in patients following infection or injury, is a leading cause of morbidity and mortality worldwide. Current immunological mechanisms do not explain the basis of cellular dysfunction and organ failure, the ultimate cause of death. Here we review current dogma and argue that it is time to delineate novel immunometabolic and neurophysiological mechanisms underlying the altered cellular bioenergetics and failure of epithelial and endothelial barriers that produce organ dysfunction and death. These mechanisms might hold the key to future therapeutic strategies.

Neural control of the immune system

Neural reflexes support homeostasis by modulating the function of organ systems. Recent advances in neuroscience and immunology have revealed that neural reflexes also regulate the immune system. Activation of the vagus nerve modulates leukocyte cytokine production and alleviates experimental shock and autoimmune disease, and recent data have suggested that vagus nerve stimulation can improve symptoms in human rheumatoid arthritis. These discoveries have generated an increased interest in bioelectronic medicine, i.e., therapeutic delivery of electrical impulses that activate nerves to regulate immune system function. Here, we discuss the physiology and potential therapeutic implications of neural immune control.

Variability is adaptability…also during weaning!

Heart rate variability in the frequency domain can now be obtained at the bedside in the ICU. Promising data suggest that it may help to characterize a patient response to a spontaneous breathing trial. Refinement of the analysis could even help to predict the outcome of extubation or at least help to detect early patients at risk of failure. It is possible that combining this type of analysis, the breathing pattern variability, and other objective indices could help clinicians in the decision-making process of weaning and extubation.

Evaluating physiological dynamics via synchrosqueezing: prediction of ventilator weaning

Oscillatory phenomena abound in many types of signals. Identifying the individual oscillatory components that constitute an observed biological signal leads to profound understanding about the biological system. The instantaneous frequency (IF), the amplitude modulation (AM), and their temporal variability are widely used to describe these oscillatory phenomena. In addition, the shape of the oscillatory pattern, repeated in time for an oscillatory component, is also an important characteristic that can be parametrized appropriately. These parameters can be viewed as phenomenological surrogates for the hidden dynamics of the biological system. To estimate jointly the IF, AM, and shape, this paper applies a novel and robust time-frequency analysis tool, referred to as the synchrosqueezing transform (SST). The usefulness of the model and SST are shown directly in predicting the clinical outcome of ventilator weaning. Compared with traditional respiration parameters, the breath-to-breath variability has been reported to be a better predictor of the outcome of the weaning procedure. So far, however, all these indices normally require at least 20 min of data acquisition to ensure predictive power. Moreover, the robustness of these indices to the inevitable noise is rarely discussed. We find that based on the proposed model, SST and only 3 min of respiration data, the ROC area under curve of the prediction accuracy is 0.76. The high predictive power that is achieved in the weaning problem, despite a shorter evaluation period, and the stability to noise suggest that other similar kinds of signal may likewise benefit from the proposed model and SST.

Developing predictive models using electronic medical records: challenges and pitfalls

While Electronic Medical Records (EMR) contain detailed records of the patient-clinician encounter - vital signs, laboratory tests, symptoms, caregivers' notes, interventions prescribed and outcomes - developing predictive models from this data is not straightforward. These data contain systematic biases that violate assumptions made by off-the-shelf machine learning algorithms, commonly used in the literature to train predictive models. In this paper, we discuss key issues and subtle pitfalls specific to building predictive models from EMR. We highlight the importance of carefully considering both the special characteristics of EMR as well as the intended clinical use of the predictive model and show that failure to do so could lead to developing models that are less useful in practice. Finally, we describe approaches for training and evaluating models on EMR using early prediction of septic shock as our example application.

Heart rate variability is associated with survival in patients with brain metastasis: a preliminary report

Impaired heart rate variability (HRV) has been demonstrated as a negative survival prognosticator in various diseases. We conducted this prospective study to evaluate how HRV affects brain metastasis (BM) patients. Fifty-one BM patients who had not undergone previous brain operation or radiotherapy (RT) were recruited from January 2010 to July 2012, and 40 patients were included in the final analysis. A 5-minute electrocardiogram was obtained before whole brain radiotherapy. Time domain indices of HRV were compared with other clinical factors on overall survival (OS). In the univariate analysis, Karnofsky performance status (KPS) <70 (P = 0.002) and standard deviation of the normal-to-normal interval (SDNN) <10 ms (P = 0.004) significantly predict poor survival. The multivariate analysis revealed that KPS <70 and SDNN <10 ms were independent negative prognosticators for survival in BM patients with hazard ratios of 2.657 and 2.204, respectively. In conclusion, HRV is associated with survival and may be a novel prognostic factor for BM patients.

Predicting 7-day survival using heart rate variability in hospice patients with non-lung cancers

BACKGROUND

A simple and accurate survival prediction tool can facilitate decision making processes for hospice patients with advanced cancers. The objectives of this study were to explore the association of cardiac autonomic functions and survival in patients with advanced cancer and to evaluate the prognostic value of heart rate variability (HRV) in 7-day survival prediction.

METHODS

A prospective study was conducted on 138 patients with advanced cancer recruited from the hospice ward of a regional hospital in southern Taiwan. Information on functional status and symptom burden of the patients was recorded. Frequency-domain HRV was obtained for the evaluation of cardiac autonomic functions at admission. The end point of the study was defined as the survival status at day 7 after admission to the hospice ward. Multivariate logistic regression analyses were performed to evaluate the independent associations between HRV indices and survival of 7 days or less.

RESULTS

The median survival time of the patients was 20 days (95% CI, 17-28 days). Results from the multivariate logistic regression analysis indicated that the natural logarithm-transformed high-frequency power (lnHFP) of a value less than 2 (OR = 3.8, p = 0.008) and ECOG performance status of 3 or 4 (OR = 3.4, p = 0.023) were significantly associated with a higher risk of survival of 7 days or less. Receiver operating characteristic (ROC) curve analysis revealed that the area under the curve was 0.71 (95% CI, 0.61-0.81).

CONCLUSIONS

In hospice patients with non-lung cancers, an lnHPF value below 2 at hospice admission was significantly associated with survival of 7 days or less. HRV might be used as a non-invasive and objective tool to facilitate medical decision making by improving the accuracy in survival prediction.

The digital patient

Despite efforts, the detection of patients who are deteriorating in hospital is often later than it should be. Several technologies could provide the basis of a solution. Recording of vital signs could be improved by both automated transmission of the measured parameters to an electronic patient record and the use of unobtrusive wearable monitors that track the patient's physiology continuously. Electronic charting systems could make the recorded vital signs readily available for further processing. Software algorithms could identify such patients with greater sensitivity and specificity than the existing, paper-based track-and-trigger systems. Electronic storage of vital signs also makes intelligent alerting and remote patient surveillance possible. However, the potential of these technologies depends strongly on implementation, with poor-quality deployment likely to worsen patient care.

Heart rate before ICU discharge: a simple and readily available predictor of short- and long-term mortality from critical illness

PURPOSE

A heart rate >90 bpm serves as one of four characteristics defining the systemic inflammatory response syndrome and is used in scoring systems to predict in-hospital mortality of intensive care unit (ICU) patients. Despite its central role in critical illness, specific data regarding the relationship between heart rate and outcome are rare.

METHODS

In this post hoc analysis of a prospectively collected database, we analyzed the value of heart rate averaged from four predefined time points during the last 24 h before ICU discharge as a predictor of post-ICU in-hospital and post-hospital mortality in medical ICU patients. Furthermore, the relationship between heart rate and inflammation, as well as the influence of rate control medications on the association between heart rate and outcome were identified.

RESULTS

Among the 702 ICU patients discharged from the ICU, 7.1 % died before hospital discharge. At 4 years of follow-up, post-hospital mortality was 14.4 %. Multivariate Cox proportional hazards models revealed heart rate before ICU discharge (HR 5.95; 95 % CI 1.24-28.63; p = 0.03) as an independent predictor of post-ICU in-hospital mortality. Both heart rate (HR 2.56; 95 % CI, 1.05-6.34; p = 0.04) and the C-reactive protein serum concentration before ICU discharge (HR, 1.26; 95 % CI, 1.09-1.46; p = 0.002) were independently associated with post-hospital mortality. Heart rate control therapy reduced the risk of post-ICU in-hospital (HR 0.38; 95 % CI, 0.18-0.81; p = 0.01) and post-hospital (HR, 0.47; 95 % CI, 0.22-1.00; p = 0.05) mortality.

CONCLUSION

Heart rate evaluated 24 h before ICU discharge was independently associated with post-ICU in-hospital and post-hospital mortality. Pharmacological interventions to control heart rate may beneficially influence post-ICU mortality.

Predictive monitoring for early detection of sepsis in neonatal ICU patients

PURPOSE OF REVIEW

Predictive monitoring is an exciting new field involving analysis of physiologic data to detect abnormal patterns associated with critical illness. The first example of predictive monitoring being taken from inception (proof of concept) to reality (demonstration of improved outcomes) is the use of heart rate characteristics (HRC) monitoring to detect sepsis in infants in the neonatal ICU. The commercially available 'HeRO' monitor analyzes electrocardiogram data from existing bedside monitors for decreased HR variability and transient decelerations associated with sepsis, and converts these changes into a score (the HRC index or HeRO score). This score is the fold increase in probability that a patient will have a clinical deterioration from sepsis within 24 h. This review focuses on HRC monitoring and discusses future directions in predictive monitoring of ICU patients.

RECENT FINDINGS

In a randomized trial of 3003 very low birthweight infants, display of the HeRO score reduced mortality more than 20%. Ongoing research aims to combine respiratory and HR analysis to optimize care of ICU patients.

SUMMARY

Predictive monitoring has recently been shown to save lives. Harnessing and analyzing the vast amounts of physiologic data constantly displayed in ICU patients will lead to improved algorithms for early detection, prognosis, and therapy of critical illnesses.

Possible predictors of cardiorespiratory events after immunization in preterm neonates

BACKGROUND

The influence of the first immunization on cardiorespiratory (CR) stability in very preterm infants is still a controversial subject.

OBJECTIVES

To describe the changes induced by immunization on heart and respiratory rate variability (HRV-RRV) and to test a potential association between preimmunization profiles and postimmunization CR events.

METHODS

Continuous 72-hour CR recordings and 2.5-hour polysomnographic recordings were performed on very preterm infants immunized after 7 weeks. The results are expressed as medians (interquartile ranges).

RESULTS

Immunization was performed on 31 very preterm infants [28 weeks' gestation (26.9-29), birth weight: 965 g (795-1,105)], and was associated with an increased incidence (p < 0.01) of events lasting more than 10 s: bradycardia <80 bpm [2.2 (1.1-7) vs. 1.8 (1-4)/12 h], desaturation [17.6 (9.4-36.4) vs. 13.9 (7.7-33.8)/12 h] and associated bradycardia-desaturation [IB+D, 4.1 (1.4-7.3) vs. 2.4 (1-4.6)/12 h], with mild changes in HRV and no change in RRV. The changes in IB+D frequency were correlated with preimmunization IB+D frequency (r = 0.44, p < 0.05), HRV spectral parameter low frequency/high frequency ratio (LF/HF, r = 0.55, p < 0.01) and approximate entropy of HRV (r = -0.39, p < 0.05).

CONCLUSION

The increase in CR events after the first immunization in very preterm infants was associated with: (1) sympathetic predominance in heart rate control (high LF/HF ratio), (2) abnormal oversimplification of HRV (low entropy) and (3) persistent respiratory rhythm control immaturity (high IB+D before vaccine).

The use of intravenous antibiotics at the onset of neutropenia in patients receiving outpatient-based hematopoietic stem cell transplants

Empirical antibiotics at the onset of febrile neutropenia are one of several strategies for management of bacterial infections in patients undergoing Hematopoietic Stem Cell Transplant (HSCT) (empiric strategy). Our HSCT program aims to perform HSCT in an outpatient setting, where an empiric antibiotic strategy was employed. HSCT recipients began receiving intravenous antibiotics at the onset of neutropenia in the absence of fever as part of our institutional policy from 01 Jan 2009; intravenous Prophylactic strategy. A prospective study was conducted to compare two consecutive cohorts [Year 2008 (Empiric strategy) vs. Year 2009 (Prophylactic strategy)] of patients receiving HSCT. There were 238 HSCTs performed between 01 Jan 2008 and 31 Dec 2009 with 127 and 111 in the earlier and later cohorts respectively. Infection-related mortality pre- engraftment was similar with a prophylactic compared to an empiric strategy (3.6% vs. 7.1%; p = 0.24), but reduced among recipients of autologous HSCT (0% vs. 6.8%; p = 0.03). Microbiologically documented, blood stream infections and clinically documented infections pre-engraftment were reduced in those receiving a prophylactic compared to an empiric strategy, (11.7% vs. 28.3%; p = 0.001), (9.9% vs. 24.4%; p = 0.003) and (18.2% vs. 33.9% p = 0.007) respectively. The prophylactic use of intravenous once-daily ceftriaxone in patients receiving outpatient based HSCT is safe and may be particularly effective in patients receiving autologous HSCT. Further studies are warranted to study the impact of this Prophylactic strategy in an outpatient based HSCT program.

Monitoring and identification of sepsis development through a composite measure of heart rate variability

Tracking the physiological conditions of a patient developing infection is of utmost importance to provide optimal care at an early stage. This work presents a procedure to integrate multiple measures of heart rate variability into a unique measure for the tracking of sepsis development. An early warning system is used to illustrate its potential clinical value. The study involved 17 adults (age median 51 (interquartile range 46-62)) who experienced a period of neutropenia following chemoradiotherapy and bone marrow transplant; 14 developed sepsis, and 3 did not. A comprehensive panel (N = 92) of variability measures was calculated for 5 min-windows throughout the period of monitoring (12 ± 4 days). Variability measures underwent filtering and two steps of data reduction with the objective of enhancing the information related to the greatest degree of change. The proposed composite measure was capable of tracking the development of sepsis in 12 out of 14 patients. Simulating a real-time monitoring setting, the sum of the energy over the very low frequency range of the composite measure was used to classify the probability of developing sepsis. The composite revealed information about the onset of sepsis about 60 hours (median value) before of sepsis diagnosis. In a real monitoring setting this quicker detection time would be associated to increased efficacy in the treatment of sepsis, therefore highlighting the potential clinical utility of a composite measure of variability.

Heart rate variability - a potential early marker of sub-acute post-stroke infections

OBJECTIVE

Infection is the most relevant complication after acute ischemic stroke. Activity of the autonomic nervous system seems to control post-stroke immunodepression. We investigated heart rate variability (HRV) indices that reflect autonomic readjustments as predictors of post-stroke infection.

MATERIALS AND METHODS

Forty-three patients with acute ischemic stroke were enrolled in a prospective study. The predictability of sub-acute infections (day 4 ± 1 after admission) was investigated in 34 patients without acute infection by means of HRV indices obtained in the acute period (48 h after admission).

RESULTS

Sub-acute infection could be predicted in patients without clinical or paraclinical (white blood cell count and C-reactive protein) signs of infection in the acute period at (i) day: increased HFnorm, reduced LFnorm and LF/HF; (ii) night: reduced LF and VLF (P < 0.05).

CONCLUSIONS

HRV indices are candidates for early markers of developing post-stroke infections, preceding routine blood samples. Thus, HRV-based early diagnosis of post-stroke infection should be investigated in more detail as it may have implications as a novel tool for timely and appropriate treatment. A corresponding continuous HRV-based risk assessment using the ECG provided by the routine stroke monitoring system would be possible without any additional burden for patients and staff.

Entropy analysis of tri-axial leg acceleration signal waveforms for measurement of decrease of physiological variability in human gait

Disease-related and senescent decrease of physiological variability in biological time-series outputs (e.g., heart rate) has drawn increasing attention as a potential new type of biomarker. In this paradigm, measurement of variability in periodic motion may enable quantitative evaluation of functional limitation in people with musculoskeletal disorders. A novel technique to measure variability of leg motion patterns during level walking was used to study 52 adults with symptomatic knee osteoarthritis (OA), and 57 asymptomatic control subjects over a wide range of age (20-79 years). The hypothesis was that cycle-to-cycle variability in leg motion patterns, indexed by tri-axial acceleration signal entropy, would be lower in those with greater age or with knee symptoms. Leg motions were assessed using portable inertial monitors attached bilaterally just above each ankle. The tri-axial acceleration data were analyzed using a nonlinear variability measurement tool designated as Sample Entropy (SampEn). SampEn data for asymptomatic subjects exhibited a significant negative correlation (r = -0.287, p = 0.0306) with greater age. OA subjects had significantly lower SampEn values (p = 0.0002) than did age-matched asymptomatic subjects who walked at equivalent velocity. This approach holds promise as a basis for valid, inexpensive, and convenient objective evaluation of limitations in human gait function.

Reduction of heart rate variability after colorectal resections

BACKGROUND

Heart rate variability (HRV) is a sensitive marker of altered sympathetic-parasympathetic function and is reduced in inflammation, illness, and trauma. The effect of major abdominal surgery on the course of HRV parameters is still an issue requiring further investigation.

MATERIALS AND METHODS

A prospective, observational study including 40 consecutive patients undergoing elective colorectal surgery under "fast-track" perioperative management. Time and frequency domain parameters of HRV were measured 1 day prior to operation and on days 1-5 postoperatively. General and surgical complications as well as the course of leucocytes and C-reactive protein (CRP) were documented and correlated to the HRV measurements.

RESULTS

Time domain parameters of HRV showed a significant decrease compared to the preoperative values on postoperative day 1 and returned to baseline on day 2, demonstrating impaired autonomic regulation in the early postoperative period. No correlation to complications or course of leukocytes or CRP was significant in our study.

CONCLUSIONS

Colorectal resections significantly influence the HRV course. The autonomic regulation is reduced in the early postoperative time and all parameters return to baseline until the third day.

Effects of a peripheral cholinesterase inhibitor on cytokine production and autonomic nervous activity in a rat model of sepsis

PURPOSE

Recently, cholinergic anti-inflammatory pathway manipulation has been proposed as a new strategy to control cytokine production in sepsis. We investigated whether hypercytokinemia can be controlled via this pathway in an animal model of sepsis, with concomitant monitoring of autonomic nervous activity involving heart rate variability (HRV) analysis of electrocardiographic R-R intervals.

METHODS

Sixty-eight adult male Sprague-Dawley rats were used (28 for examination of cytokine production and autonomic nervous activity; 40 for survival analysis). Each part of the study involved four animal groups, including two control groups without drug administration. Sepsis was induced by cecal ligation and puncture (CLP). Distigmine bromide, a peripheral, non-selective cholinesterase inhibitor (0.01mg/kg), was administered subcutaneously 90 min after surgery. Continuous electrocardiograms were recorded for 5 min before and after surgery (at intervals of 5h) in CLP and sham-operated animals for HRV analysis. Blood samples were collected 20 h after surgery for serum cytokine and catecholamine assay.

RESULTS

On HRV analysis, distigmine inhibited reduction of total power and high-frequency components in CLP animals (P<0.05). Distigmine significantly inhibited cytokine induction (IL-6 and IL-10) (P<0.01) as well as increase in serum levels of noradrenaline and dopamine (P<0.05). Distigmine did not significantly improve CLP animal survival rate.

CONCLUSIONS

The cholinesterase inhibitor distigmine inhibited induction of inflammatory cytokines and catecholamines as well as HRV suppression in a rat CLP model, suggesting that an agent modulating the cholinergic anti-inflammatory pathway can control excess cytokine production involved in the pathogenesis of severe sepsis/septic shock.

State classification of heart rate variability by an artificial neural network in frequency domain

This paper examines the feasibility of accurate state classification of autonomic nervous activity (ANA) based on the power spectral pattern of the heart rate fluctuations (HRFs). Some attempts have been made to utilize artificial neural networks (ANNs) to classify HRFs for clinical diagnoses such as ischemic cardiomyopathy, arrhythmia or sleep apnea. To establish the firm bases for making such clinical diagnoses, it may be important to examine the classification accuracy for the data in physiologically well defined conditions by e.g. application of autonomic blocking agents. In this paper the three layered perceptron has been trained by the heart rate data in variety of ANS states yielded by the application of Atropine and Propranolol to 14 healthy male subjects. Six state (control, atropine and propranolol for each of the spine and upright posture) classification based on power spectrum showed average sensitivity of 67.2% and specificity 91.2%. Four state (control, atropine, propranolol and double block for either spine or upright posture) resulted in the average classification sensitivity of 75.7% and specificity 95.5%. The paper revealed that entropy bandwidth and indices originated from characteristic oscillations of blood pressure change improve the classification accuracy.

Association between frequency domain heart rate variability and unplanned readmission to hospital in geriatric patients

Background

An accurate prediction of unplanned readmission (UR) after discharge from hospital can facilitate physician's decision making processes for providing better quality of care in geriatric patients. The objective of this study was to explore the association of cardiac autonomic functions as measured by frequency domain heart rate variability (HRV) and 14-day UR in geriatric patients.

Methods

Patients admitted to the geriatric ward of a regional hospital in Chiayi county in Taiwan were followed prospectively from July 2006 to June 2007. Those with invasive tubes and those who were heavy smokers, heavy alcohol drinkers, on medications that might influence HRV, or previously admitted to the hospital within 30 days were excluded. Cardiac autonomic functions were evaluated by frequency domain indices of HRV. Multiple logistic regression was used to assess the association between UR and HRV indices adjusted for age and length of hospitalization.

Results

A total of 78 patients met the inclusion criteria and 15 of them were readmitted within 14 days after discharge. The risk of UR was significantly higher in patients with lower levels of total power (OR = 1.39; 95% CI = 1.04-2.00), low frequency power (LF) (OR = 1.22; 95% CI = 1.03-1.49), high frequency power (HF) (OR = 1.27; 95% CI = 1.02-1.64), and lower ratios of low frequency power to high frequency power (LF/HF ratio) (OR = 1.96; 95% CI = 1.07-3.84).

Conclusion

This is the first study to evaluate the association between frequency domain heart rate variability and the risk of UR in geriatric patients. Frequency domain heart rate variability indices measured on admission were significantly associated with increased risk of UR in geriatric patients. Additional studies are required to confirm the value and feasibility of using HRV indices on admission as a non-invasive tool to assist the prediction of UR in geriatric patients.