Relation of impaired interorgan communication and parasympathetic activity in chronic heart failure and multiple-organ dysfunction syndrome

Heart rate variability as a marker of multiple organ dysfunction syndromes: a systematic review

Multiple organ dysfunction syndrome (MODS) can be caused by many factors. Assessments of the severity of MODS are currently based on occasional measurements of several clinical variables (laboratory data, vital signs, etc.). The analysis of heart rate variability (HRV) as a guide to autonomic nervous system activity might be of value in the continuous assessment of the severity of MODS. We systematically reviewed publications on the value of HRV variables for the diagnosis of MODS in patients of any age admitted to the ICU. Two investigators independently searched the PubMed, Embase, Cochrane and Science Direct databases for articles in English or French published between 2004 and 2024. Ten studies were included and rated for endpoint bias (MODS or mortality), using the revised Quality Assessment of Diagnostic Accuracy Studies. Nine studies assessed MODS, and six assessed mortality. All the studies evidenced low HRV in patients with MODS and in non-survivors. The results of our review show that HRV indices are influenced by the severity of MODS and might serve as a tool for predicting mortality in patients with MODS. However, patient characteristics, and treatments and HRV processing methods must be taken into account when interpreting the results. In order to clarify the impact of MODS on HRV variables, methodologically rigorous studies are now needed.

Predicting Time to Death After Withdrawal of Life-Sustaining Measures Using Vital Sign Variability: Derivation and Validation

To develop a predictive model using vital sign (heart rate and arterial blood pressure) variability to predict time to death after withdrawal of life-supporting measures.

[Heart rate control in shock]

Heart rate is well established in the diagnosis of shock; however, the mechanisms regulating heart rate, systemic resistance and blood pressure remain unclear. The concept of heart rate control in shock-related tachycardia has been known for about 50 years. Elevated heart rates in septic shock have been identified as an indicator of increasingly inefficient hemodynamics, worsening perfusion and organ function as well as of an unfavourable prognosis. Many drugs used for heart rate control also lower blood pressure. The challenge of this therapeutic concept is achieving optimal heart rate control without provoking critical hypotension. Only in recent years has the development of highly cardioselective, short- and ultrashort-acting β‑blockers such as esmolol and landiolol made it possible to prove the feasibility and usefulness of heart rate control in certain types of shock.

Assessment of extravascular lung water by measuring the number of pulmonary ultrasound B-lines before and after CBP in patients with MODS

To determine whether the change in the number of pulmonary ultrasound B-line can accurately assess the extravascular lung water (EVLW) before and after continuous bedside blood purification (CBP) in patients with multiple organ dysfunction syndrome (MODS).Seventy-six patients with MODS who underwent CBP were examined within 24 hours before and after CBP using pulmonary ultrasound to detect the number of ultrasound B-line or using pulse indicator continuous cardiac output method to examine extravascular lung water, blood oxygenation index, and B-type natriuretic peptide (BNP) content. The correlation of the change in the number of B lines before and after CBP treatment with the negative balance of 24 hours liquid, the change of oxygenation index, and BNP content were analyzed.In the 76 patients, CBP treatment significantly decreased EVLW, the number of B-line, and BNP (P < .05 for all), while it significantly increased the oxygenation index (P < .05). Correlation analysis showed that the decrease in B-line number after CBP treatment was positively correlated with the 24 hours negative lung fluid balance, decrease of EVLW, oxygenation index improvement, and decreased BNP content. The change in the numbers of pulmonary ultrasound B-line can accurately assess the change of EVLW before and after CBP treatment and reflect the efficiency of ventilation in the lungs and the risk of heart failure.Thus, it can replace pulse indicator continuous cardiac output as an indicator for evaluating EVLW in patients with MODS treated with CBP.

Heart rate variability and inflammation: A meta-analysis of human studies

The inflammatory reflex is known as the body's primary defense against infection and has been implicated in a number of diseases. The magnitude of the inflammatory response is important, as an extreme or insufficient response can be differentially harmful to the individual. Converging evidence suggests that the autonomic nervous system (ANS) regulates the inflammatory reflex. Heart rate variability (HRV) can be separated into components that primarily reflect parasympathetic (PNS) or vagal activity (i.e., indices of vagally mediated HRV) and a combination of both sympathetic (SNS) and PNS influences. Given the physiological relation between the vagus and inflammatory processes, one would expect to find higher HRV, especially indices of vagally-mediated HRV, to be associated with decreased levels of inflammation via the cholinergic anti-inflammatory pathway. However, existing findings here are mixed, such that studies have also shown a positive association between indices of HRV and markers of inflammation. Therefore, the present meta-analysis aimed to synthesize existing studies, estimating the general direction and strength of the relationship between different indices of HRV and inflammatory markers. A systematic search of the literature yielded 2283 studies that were screened for inclusion eligibility (159 studies eligible for inclusion); in sum, 51 studies reported/provided adequate information for inclusion in meta-analyses. Results generally showed negative associations between indices of HRV and markers of inflammation. In this regard, the standard deviation of R-R intervals (SDNN) and power in the high frequency band of HRV (HF-HRV) showed the strongest and most robust associations with inflammatory markers compared to other time- and frequency-domain measures of HRV. Overall, we propose that indices of HRV can be used to index activity of the neurophysiological pathway responsible for adaptively regulating inflammatory processes in humans.

Spectral analysis of heart rate variability for trauma outcome prediction: an analysis of 210 ICU multiple trauma patients

PURPOSE

This study aimed to test and compare short-term spectral HRV indices with most used trauma scorings in outcome prediction of multiple trauma, and then to explore the efficacy of their combined application.

METHODS

A prospective study was conducted for patients with blunt multiple trauma admitted to an emergency intensive care unit (ICU) between January 2016 and December 2017. Short-term spectral HRV indices on admission were measured, including normalized low-frequency power (nLF), normalized high-frequency power (nHF), and the nLF/nHF ratio. Injury severity score (ISS), new injury severity score (NISS), and revised trauma score (RTS) were evaluated for each patient, as well as probability of survival (Ps) by trauma and injury severity score (TRISS) model. The primary outcome was 30-day mortality and secondary outcomes were incidence of multiple organ dysfunction syndrome (MODS) and length of ICU stay.

RESULTS

Two hundred and ten patients were recruited. The nLF/nHF ratio, RTS, and Ps_(TRISS) were independent predictors of 30-day mortality, while nLF/nHF, NISS and RTS were independent predictors of MODS. The area under the receiver operating characteristic (ROC) curve (AUC) of nLF/nHF for 30-day mortality prediction was 0.924, comparable to RTS (0.951) and Ps_(TRISS) (0.892). AUC of nLF/nHF-RTS combination was 0.979, significantly greater than that of each alone. Combination of nLF/nHF and Ps_(TRISS) showed an increased AUC (0.984) compared to each of them. The nLF/nHF ratio presented a similar AUC (0.826) to NISS (0.818) or RTS (0.850) for MODS prediction. AUC of nLF/nHF-RTS combination was 0.884, significantly greater than that of nLF/nHF. Combination of nLF/nHF and NISS showed a greater AUC (0.868) than each alone. The nLF/nHF ratio, NISS, RTS, and Ps_(TRISS) were correlated with length of ICU stay for survivors, with correlation coefficients 0.476, 0.617, - 0.588, and - 0.539.

CONCLUSIONS

These findings suggest that the short-term spectral analysis of HRV might be a potential early tool to assess injury severity and predict outcome of multiple trauma. Combination of nLF/nHF and conventional trauma scores can provide more accuracy in outcome prediction of multiple trauma.

Alterations of the respiratory system in heart failure

The review discusses mechanisms for the development of the pathology of the respiratory system in patients with CHF, such as various types of periodic respiration, pulmonary hypertension due to the pathology of the left chambers of the heart, and remodeling of the respiratory musculature. The role of chemo- and baroreceptors of the carotid zone, as well as the hyperactivation of the respiratory muscle metaboreflex in the development of the pathology of the respiratory system, and the mediated exacerbation of CHF are discussed.

Personalized physiological medicine

This paper introduces the concept of personalized physiological medicine that is specifically directed at the needs of the critically ill patient. This differs from the conventional view of personalized medicine, characterized by biomarkers and gene profiling, instead focusing on time-variant changes in the pathophysiology and regulation of various organ systems and their cellular and subcellular constituents. I propose that personalized physiological medicine is composed of four pillars relevant to the critically ill patient. Pillar 1 is defined by the frailty and fitness of the patient and their physiological reserve to cope with the stress of critical illness and therapy. Pillar 2 involves monitoring of the key physiological variables of the different organ systems and their response to disease and therapy. Pillar 3 concerns the evaluation of the success of resuscitation by assessment of the hemodynamic coherence between the systemic and microcirculation and parenchyma of the organ systems. Finally, pillar 4 is defined by the integration of the physiological and clinical data into a time-learning adaptive model of the patient to provide feedback about the function of organ systems and to guide and assess the response to disease and therapy. I discuss each pillar and describe the challenges to research and development that will allow the realization of personalized physiological medicine to be practiced at the bedside for critically ill patients.

Safety and efficacy of regional citrate anticoagulation in continuous blood purification treatment of patients with multiple organ dysfunction syndrome

The aim of this study was to discuss the safety and efficacy of regional citrate anticoagulation (RCA) on continuous blood purification (CBP) during the treatment of multiple organ dysfunction syndrome (MODS). Thirty-five patients with MODS were divided into two groups: the local citrate anticoagulation (RCA) group, and the heparin-free blood purification (hfBP) group. The MODS severity was assessed according to Marshall's MODS score criteria. Blood coagulation indicators, blood pressure, filter lifespan, filter replacement frequency, anticoagulation indicators, and main metabolic and electrolyte indicators were analyzed and compared between RCA and hfBP groups. RCA resulted in lower blood pressure than hfBP. The filter efficacy in RCA treatment was longer than in the hfBP group. The blood clearance of creatine, blood urea nitrogen and uric acid was better in the RCA group. RCA also led to higher pH than hfBP. Neither treatment resulted in severe bleeding events. In addition, MODS score was positively correlated with prothrombin time and activated partial thromboplastin time but negatively correlated with platelet concentration. RCA is a safer and more effective method in CBP treatment; however, it could also lead to low blood pressure and blood alkalosis.

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.

Mitochondrial multiorgan disorder syndrome score generated from definite mitochondrial disorders

OBJECTIVES

Mitochondrial disorders (MIDs) frequently present as mitochondrial multiorgan disorder syndrome (MIMODS) at onset or evolve into MIMODS during the course. This study aimed to find which organs and/or tissues are most frequently affected by MIMODS, which are the most frequent abnormalities within an affected organ, whether there are typical MIMODS patterns, and to generate an MIMODS score to assess the diagnostic probability for an MID.

METHODS

This is a retrospective evaluation of clinical, biochemical, and genetic investigations of adult patients with definite MIDs. A total of 36 definite MID patients, 19 men and 17 women, aged 29-82 years were included in this study. The diagnosis was based on genetic testing (n=21), on biochemical investigations (n=17), or on both (n=2).

RESULTS

The number of organs most frequently affected was 4 ranging from 1 to 9. MIMODS was diagnosed in 97% of patients. The organs most frequently affected were the muscle (97%), central nervous system (CNS; 72%), endocrine glands (69%), heart (58%), intestines (55%), and peripheral nerves (50%). The most frequent CNS abnormalities were leukoencephalopathy, prolonged visually evoked potentials, and atrophy. The most frequent endocrine abnormalities included thyroid dysfunction, short stature, and diabetes. The most frequent cardiac abnormalities included arrhythmias, systolic dysfunction, and hypertrophic cardiomyopathy. The most frequent MIMODS patterns were encephalomyopathy, encephalo-myo-endocrinopathy, and encepalo-myo-endocrino-cardiopathy. The mean ± 2SD MIMODS score was 35.97±27.6 (range =11-71). An MIMODS score >10 was regarded as indicative of an MID.

CONCLUSION

Adult MIDs manifest as MIMODS in the vast majority of the cases. The organs most frequently affected in MIMODS are muscles, CNS, endocrine glands, and heart. An MIMODS score >10 suggests an MID.