Many behavioral phenomena have been found to spread interpersonally through social networks, in a manner similar to infectious diseases. An important difference between social contagion and traditional infectious diseases, however, is that behavioral phenomena can be acquired by non-social mechanisms as well as through social transmission. We introduce a novel theoretical framework for studying these phenomena (the SISa model) by adapting a classic disease model to include the possibility for ‘automatic’ (or ‘spontaneous’) non-social infection. We provide an example of the use of this framework by examining the spread of obesity in the Framingham Heart Study Network. The interaction assumptions of the model are validated using longitudinal network transmission data. We find that the current rate of becoming obese is 2 per year and increases by 0.5 percentage points for each obese social contact. The rate of recovering from obesity is 4 per year, and does not depend on the number of non-obese contacts. The model predicts a long-term obesity prevalence of approximately 42, and can be used to evaluate the effect of different interventions on steady-state obesity. Model predictions quantitatively reproduce the actual historical time course for the prevalence of obesity. We find that since the 1970s, the rate of recovery from obesity has remained relatively constant, while the rates of both spontaneous infection and transmission have steadily increased over time. This suggests that the obesity epidemic may be driven by increasing rates of becoming obese, both spontaneously and transmissively, rather than by decreasing rates of losing weight. A key feature of the SISa model is its ability to characterize the relative importance of social transmission by quantitatively comparing rates of spontaneous versus contagious infection. It provides a theoretical framework for studying the interpersonal spread of any state that may also arise spontaneously, such as emotions, behaviors, health states, ideas or diseases with reservoirs.

Infectious Disease Modeling of Social Contagion in Networks

Rationale: Optimal positive end-expiratory pressure (PEEP) is unknown in patients with severe acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation receiving mechanical ventilation with very low tidal volume.Objectives: To evaluate the ability of electrical impedance tomography (EIT) to monitor a PEEP trial and to derive from EIT the best compromise PEEP in this setting.Methods: A decremental PEEP trial (20–0 cm H2O) in 5 cm H2O steps was monitored by EIT, with lung images divided into four ventral-to-dorsal horizontal regions of interest. The EIT-based PEEP providing the best compromise between overdistention and collapsed zones was arbitrarily defined as the lowest pressure able to limit EIT-assessed collapse to less than or equal to 15% with the least overdistention. Driving pressure was maintained constant at 14 cm H2O in pressure controlled mode.Measurements and Main Results: Tidal volume, static compliance, tidal impedance variation, end-expiratory lung impedance, and the...

https://www.atsjournals.org/doi/pdf/10.1164/rccm.201605-1055OC

Bedside Contribution of Electrical Impedance Tomography to Setting Positive End-Expiratory Pressure for Extracorporeal Membrane Oxygenation-treated Patients with Severe Acute Respiratory Distress Syndrome.

BackgroundChanges in autonomic nervous system (ANS) function have been observed in a variety of psychological disorders, including posttraumatic stress disorder (PTSD). Analysis of heart rate variability (HRV) provides insight into the functioning of the ANS. Previous research on PTSD found lower HRV in PTSD patients compared to controls, indicating altered sympathetic and parasympathetic activity, but findings are inconsistent. The purpose of this meta-analysis was to examine differences in HRV indices between individuals with PTSD and healthy controls at baseline and during stress.MethodsThe included primary studies present an aggregate of studies analyzing different HRV indices. Examined HRV indices were standard deviation of the normalized NN-intervals (SDNN), root mean square of successive differences (RMSSD), low-frequency (LF) and high-frequency (HF) spectral components, LF/HF ratio, and heart rate (HR). Moderating effects of study design, HRV and PTSD assessment, and sample characteristics were examined via subgroup-analyses and meta-regressions.ResultsRandom-effects meta-analyses for HRV parameters at rest revealed significant group differences for RMSSD and HF-HRV, suggesting lower parasympathetic activity in PTSD. The aggregated effect size for SDNN was medium, suggesting diminished total variability in PTSD. A small effect was found for LF-HRV. A higher LF/HF ratio was found in the PTSD sample as compared to controls. Individuals with PTSD showed significantly higher HR. During stress, individuals with PTSD showed higher HR and lower HF-HRV, both indicated by small effect sizes.ConclusionsFindings suggest that PTSD is associated with ANS dysfunction.

/pdf/autonomic-dysfunction-in-posttraumatic-stress-disorder-4sor4dok4f.pdf

Autonomic dysfunction in posttraumatic stress disorder indexed by heart rate variability: a meta-analysis.

Assessment of Lung Recruitment by Electrical Impedance Tomography and Oxygenation in ARDS Patients

Pulmonary function testing and monitoring plays an important role in the respiratory management of neonates. A noninvasive and complete bedside evaluation of the respiratory status is especially useful in critically ill neonates to assess disease severity and resolution and the response to pharmacological interventions as well as to guide mechanical respiratory support. Besides traditional tools to assess pulmonary gas exchage such as arterial or transcutaenous blood gas analysis, pulse oximetry, and capnography, additional valuable information about global lung function is provided through measurement of pulmonary mechanics and volumes. This has now been aided by commercially available computerized pulmonary function testing systems, respiratory monitors, and modern ventilators with integrated pulmonary function readouts. In an attempt to apply easy-to-use pulmonary function testing methods which do not interfere with the infants airflow, other tools have been developed such as respiratory inductance plethysmography, and more recently, electromagnetic and optoelectronic plethysmography, electrical impedance tomography, and electrical impedance segmentography. These alternative technologies allow not only global, but also regional and dynamic evaluations of lung ventilation. Although these methods have proven their usefulness for research applications, they are not yet broadly used in a routine clinical setting. This review will give a historical and clinical overview of different bedside methods to assess and monitor pulmonary function and evaluate the potential clinical usefulness of such methods with an outlook into future directions in neonatal respiratory diagnostics.

Evaluation of bedside pulmonary function in the neonate: From the past to the future.

Heart rate variability (HRV): From brain death to resonance breathing at 6 breaths per minute.

Lung failure after acute lung injury remains a challenge in different clinical settings. Various interventions for restoration of gas exchange have been investigated. Recruitment of collapsed alveoli by positive end expiratory pressure (PEEP) titration and optimization of ventilation-perfusion ratio by prone positioning have been extensively described in animal and clinical trials. This animal study was conducted to investigate the effects of PEEP and positioning by means of advanced respiratory monitoring including gas exchange, respiratory mechanics, volumetric capnography and electrical impedance tomography. After induction of acute lung injury by oleic acid and lung lavage, 12 domestic pigs were studied in randomly assigned supine or prone position during a PEEP titration trial with maximal PEEP of 30 mbar. Induction of lung injury resulted in significant deterioration of oxygenation [partial pressure of arterial oxygen/inspiratory fraction of oxygen (PaO2/FiO2): p = 0.002] and ventilation [partial pressure of arterial carbon dioxide (PaCO2): p = 0.002] and elevated alveolar dead-space ratios (Valv/Vte: p = 0.003) in both groups. Differences in the prone and the supine group were significant for PaCO2 at incremental PEEP 10 and 20 and at decremental PEEP 20 (20d) and 10 (10d), for PaO2/FiO2 at PEEP 10 and 10d and for alveolar dead space at PEEP 10d. Electrical impedance tomography revealed homogenous ventilation distribution in prone position during PEEP 20, 30 and 20d. Prone position leads to improved oxygenation and ventilation parameters in a lung injury model. Respiratory monitoring with measurement of alveolar dead space and electrical impedance tomography may visualize optimized ventilation in a PEEP titration trial.

https://link.springer.com/content/pdf/10.1186%2Fs40635-014-0038-6.pdf

Effect of body position on ventilation distribution during PEEP titration in a porcine model of acute lung injury using advanced respiratory monitoring and electrical impedance tomography.

l lcart rate variability ( I IRV) is frequently used to study hean rate regulation and therewith especially the lunct ion l thc brain slem [1,2]. Previous studies have mdicated that the Cerebral Function Analysis Monitor ( (ΤΑΜ) is a powerful tool to evaluate continuously cerebral funetion in the Neonatal Intensive Gare Unit 1 3. 4.5 1 . Λ combination of both, HRV and clcctroencephalogram (EEG) measurements are thercfore suitable to monitor at the same time the functioning of cortical and brain stem structures [6]. The goal of this paper is to demonstrate the first time a combined HRV-EEG monitoring in neonates with very low birth weight (VLBW).

Klaus Pfurtscheller

Papers

Heart rate variability (HRV): From brain death to resonance breathing at 6 breaths per minute.

Effect of body position on ventilation distribution during PEEP titration in a porcine model of acute lung injury using advanced respiratory monitoring and electrical impedance tomography.

Coherent behavior of eec activity and heart rate variability in premature infants