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

Abstract

Bacterial infection leading to organ failure is the most common cause of death in critically ill patients. Early diagnosis and expeditious treatment is a cornerstone of therapy. Evaluating the systemic host response to infection as a complex system provides novel insights: however, bedside application with clinical value remains wanting. Providing an integrative measure of an altered host response, the patterns and character of heart rate fluctuations measured over intervals-in-time may be analysed with a panel of mathematical techniques that quantify overall fluctuation, spectral composition, scale-free variation, and degree of irregularity or complexity. Using these techniques, heart rate variability (HRV) has been documented to be both altered in the presence of systemic infection, and correlated with its severity. In this review and analysis, we evaluate the use of HRV monitoring to provide early diagnosis of infection, document the prognostic implications of altered HRV in infection, identify current limitations, highlight future research challenges, and propose improvement strategies. Given existing evidence and potential for further technological advances, we believe that longitudinal, individualized, and comprehensive HRV monitoring in critically ill patients at risk for or with existing infection offers a means to harness the clinical potential of this bedside application of complex systems science.

Influence of Cancer Severity and Functional Status of Cancer on Cardiac Parasympathetic Indicators

“…In cancer patients, ECOG score was widely applied for survival analysis in an advanced stage of cancer [18]. Indices of parasympathetic function are considered to be independent predictors of mortality in health and disease conditions including cancer [19][20][21][22]. However, no data are available on the relationship between cardiac vagal function and ECOG score in cancer patients.…”

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

“…Short-term variations in airway function are dependent mainly on intrinsic factors, such as mean airway caliber, posture, bronchial reactivity, airway smooth muscle loading, end-expiratory lung volume, and viscoelastic properties of lung, as well as extrinsic factors, such as methacholine and bronchodilators (1,15,(21)(22)(23)(24). The sources of these variations are difficult to disentangle, are different between asthma and COPD, and have been associated with disease severity and inflammatory phenotypes (25).…”

“…The potential clinical value of monitoring variability has been investigated with respect to early warning of sepsis (24,91,92) as well as prognostication of organ failure and the impact of sedation (93,94). In addition, increased age leads to degradation of the multiscale self-similar behavior seen in RRV, with loss of long-range fractal scaling, signifying loss of complexity (5).…”

Implantable Cardiac Devices and the Acute Care Management of Decompensated Heart Failure

“…Other illnesses and comorbidities that manifest with a ramping up of sympathetic tone also present with a decrease in heart rate variability, such as seen in exacerbation of chronic obstructive pulmonary disease [34] or various infectious states [35]. Examination of all parameters captured by the implantable device will give a more complete understanding of the patient's clinical picture.…”