scholarly journals Conditional symbolic analysis detects nonlinear influences of respiration on cardiovascular control in humans

2015 ◽  
Vol 373 (2034) ◽  
pp. 20140096 ◽  
Author(s):  
Alberto Porta ◽  
Andrea Marchi ◽  
Vlasta Bari ◽  
Karsten Heusser ◽  
Jens Tank ◽  
...  
Keyword(s):  
Time Course ◽  
Muscle Sympathetic Nerve Activity ◽  
Systolic Arterial Pressure ◽  
Symbolic Analysis ◽  
Cardiovascular Control ◽  
Experimental Conditions ◽  
Sympathetic Modulation ◽  
Life Threatening ◽  
Head Up Tilt ◽  
Threatening Situation

We propose a symbolic analysis framework for the quantitative characterization of complex dynamical systems. It allows the description of the time course of a single variable, the assessment of joint interactions and an analysis triggered by a conditioning input. The framework was applied to spontaneous variability of heart period (HP), systolic arterial pressure (SAP) and integrated muscle sympathetic nerve activity (MSNA) with the aim of characterizing cardiovascular control and nonlinear influences of respiration at rest in supine position, during orthostatic challenge induced by 80° head-up tilt (TILT) and about 3 min before evoked pre-syncope signs (PRESY). The approach detected (i) the exaggerated sympathetic modulation and vagal withdrawal from HP variability and the increased presence of fast MSNA variability components during PRESY compared with TILT; (ii) the increase of the SAP–HP coordination occurring at slow temporal scales and a decrease of that occurring at faster time scales during PRESY compared with TILT; (iii) the reduction of the coordination between fast MSNA and SAP patterns during TILT and PRESY; (iv) the nonlinear influences of respiration leading to an increased likelihood to observe the abovementioned findings during expiration compared with inspiration one. The framework provided simple, quantitative indexes able to distinguish experimental conditions characterized by different states of the autonomic nervous system and to detect the early signs of a life threatening situation such as postural syncope.

Influences of neural mechanisms on heart period and arterial pressure variabilities in quadriplegic patients

1994 ◽  
Vol 266 (3) ◽  
pp. H1112-H1120 ◽  
Author(s):  
S. Guzzetti ◽  
C. Cogliati ◽  
C. Broggi ◽  
C. Carozzi ◽  
D. Caldiroli ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Spectral Component ◽  
Systolic Arterial Pressure ◽  
Neural Mechanisms ◽  
Heart Period ◽  
Recording Session ◽  
Sympathetic Modulation ◽  
Arterial Pressure Variability ◽  
Head Up Tilt ◽  
Vasomotor Activity

The heart period (R-R) variability power spectrum presents two components, at low (LF; approximately 0.10 Hz) and high (approximately 0.25 Hz) frequencies, whose reciprocal powers appear to furnish an index of sympathovagal interaction modulating heart rate. In addition, the LF component of the systolic arterial pressure variability spectrum furnishes a marker of sympathetic modulation of vasomotor activity. The contribution of spinal and supraspinal neural circuits to the genesis of these rhythmic oscillatory components remains largely unsettled. Therefore we performed spectral analysis of R-R and systolic arterial pressure variabilities in 15 chronic neurologically complete quadriplegic patients (QP) and in 15 control subjects during resting conditions, controlled respiration, and head-up tilt. At rest, in seven QP the LF component was undetectable in both cardiovascular variability spectra; in two QP this component was present only in R-R variability spectrum, whereas the remaining six showed a significantly reduced LF in both signals. In QP, the LF component, when present, underwent paradoxical changes with respect to controls, decreasing during tilt and increasing during controlled respiration. In five QP in whom the recording session was repeated after 6 mo, a significant increase in LF was observed in both variability spectra. These data confirm the finding that a disconnection of sympathetic outflow from supraspinal centers can cause the disappearance of the LF spectral component. However, LF presence in some QP supports the hypothesis of a spinal rhythmicity likely to be modulated by the afferent sympathetic activity.

Pulse Photoplethysmographic Analysis Estimates the Sympathetic Activity Directed to Heart and Vessels

2015 ◽  
Vol 123 (2) ◽  
pp. 336-345 ◽  
Author(s):  
Riccardo Colombo ◽  
Andrea Marchi ◽  
Beatrice Borghi ◽  
Tommaso Fossali ◽  
Roberto Rech ◽  
...  
Keyword(s):  
Heart Rate ◽  
High Frequency ◽  
Sympathetic Activity ◽  
Baroreflex Sensitivity ◽  
Systolic Arterial Pressure ◽  
Experimental Conditions ◽  
Arterial Pressure Variability ◽  
Head Up Tilt ◽  
Normalized Units ◽  
Good Agreement

Abstract Background: Novel pulse photoplethysmographic–derived indices have been proposed as tools to measure autonomic nervous system (ANS) modulation in anesthetized and awake patients, but nowadays their experimental validation is lacking. The authors aimed to investigate the ability of pulse photoplethysmographic amplitude (PPGA), ANS state (ANSS), and ANSS index (ANSSi) to measure changes of ANS modulation in response to sympathetic stimulation. Methods: Ten awake healthy volunteers underwent two passive head-up tilts at 45° and 90°. The heart rate variability (HRV) and systolic arterial pressure variability were analyzed in the frequency domain as a measure of ANS modulation directed to the heart and the vessels. HRV, baroreflex sensitivity, and pulse photoplethysmographic indices were measured at baseline and after tilt maneuvers. The agreement between HRV-derived indices and pulse photoplethysmographic indices was assessed using Bland–Altman plots. Results: PPGA, ANSS, and ANSSi changed significantly during the study protocol. Head-up tilt decreased PPGA and ANSS and increased ANNSi. There was a good agreement between ANSSi and baroreflex sensitivity explored in the high-frequency band (bias, 0.23; 95% CI, −22.7 to 23.2 normalized units) and between ANSSi and the sympathovagal modulation directed to the heart (bias, 0.96; 95% CI, −8.7 to 10.8 normalized units). Conclusions: In controlled experimental conditions, novel pulse plethysmographic indices seem to estimate the changes of the sympathetic outflow directed to the vessels and the sympathovagal balance modulating heart rate. These indices might be useful in the future to monitor the fluctuation of sympathetic activity in anesthetized patients.

scholarly journals Influence of Gravitational Sympathetic Stimulation on the Surgical Plethysmographic Index

2015 ◽  
pp. 183-189 ◽  
Author(s):  
R. COLOMBO ◽  
A. MARCHI ◽  
B. BORGHI ◽  
T. FOSSALI ◽  
E. TOBALDINI ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Study Protocol ◽  
Confounding Factor ◽  
Systolic Arterial Pressure ◽  
Sympathetic Outflow ◽  
Sympathetic Stimulation ◽  
Sympathetic Modulation ◽  
Head Up Tilt ◽  
Hrv Analysis

Surgical Plethysmographic Index (SPI), calculated from pulse photo-plethysmographic amplitude oscillations, has been proposed as a tool to measure nociception anti-nociception balance during general anesthesia, but it is affected by several confounding factor that alter the autonomic nervous system (ANS) modulation. We hypothesized that SPI may be mainly affected by sympathetic stimulation independently from nociception. We studied the effects of two sympathetic stimuli on SPI, delivered through passive head-up tilt at 45 and 90 degrees angles, in nine awake healthy adults. The sympathetic modulation was assessed by means of heart rate variability (HRV) analysis. Mean (SD) SPI significantly increased from baseline to 45 degrees [from 38.6 (13.7) to 60.8 (7.6), p<0.001)] and to 90 degrees angle tilt [82.3 (5.4), p<0.001]. The electrocardiographic mean R-to-R interval significantly shortened during both passive tilts, whereas systolic arterial pressure did not change during the study protocol. HRV changed significantly during the study protocol towards a predominance of sympathetic modulation during passive tilt. Gravitational sympathetic stimulation at two increasing angles, in absence of any painful stimuli, affects SPI in awake healthy volunteers. SPI seems to reflect the sympathetic outflow directed to peripheral vessels.

A Simple Method for Estimation of Lipoxygenase and Cyclo-Oxygenase Pathways in Human Platelets - the Use of Thiobarbituric Acid Reaction

1980 ◽  
Vol 44 (02) ◽  
pp. 111-114 ◽  
Author(s):  
Hiroshi Takayama ◽  
Minoru Okuma ◽  
Haruto Uchino
Keyword(s):  
Time Course ◽  
Normal Values ◽  
Human Platelet ◽  
Thiobarbituric Acid ◽  
Human Platelets ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Simple Method ◽  
Acid Reaction ◽  
Optimal Ph

SummaryTo develop a simple method for estimation of platelet lipoxygenase (PLO) and cyclo-oxygenase (PCO) pathways, the arachidonic acid (AA) metabolism of human platelet was investigated under various experimental conditions by the use of the thiobarbituric acid (TBA) reaction and a radioisotope technique. A TBA-reactive substance different from malondialdehyde (MDA) via PCO pathway was detected and shown to be derived from the PLO pathway. Since the optimal pH and time course of its formation were different from those of MDA formation via PCO pathway, PLO and PCO pathways were estimated by quantitating the TBA-reactive substances produced by the incubation of AA either with aspirin-treated platelets or with untreated ones, respectively, each under optimal conditions. Normal values expressed in terms of nmol MDA/108 platelets were 1.17±0.34 (M±SD, n = 31) and 0.79±0.15 (n = 31) for PLO and PCO pathways, respectively.

Gendered Impact of Corruption in Healthcare Service Delivery in Nigeria

2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Yetunde A. Aluko
Keyword(s):  
Service Delivery ◽  
Public Hospitals ◽  
Public Health Care ◽  
Women's Voices ◽  
Medical Supplies ◽  
Poor Women ◽  
Level Information ◽  
Life Threatening ◽  
Threatening Situation ◽  
The Impact

This paper supports the hypothesis that corruption and non-delivery of services in key sectors such as health have gender-specific poverty consequences. The study utilized qualitative micro-level information about the structures of corruption and its impact on poor women. Respondents expressed their perceptions on the occurrence of corrupt practices in public health care system and its wider impact on society. The findings revealed that the impact of corruption is felt disproportionately by women and the poor, who are most dependent on public services, and have no alternative even when facing corrupt practices in a life threatening situation, such as complicated birth delivery. Pregnant women denied access to doctors tended to deliver at home, which increased the likelihood of complications and maternal and child mortality. Medical supplies meant for public hospitals are sold to private clinics who charge more for drugs and supplies. There is need to strengthen sectoral oversight mechanisms and transparency as well as increase women’s voices in service delivery.

Understanding Process Variables and their Interactions for Maximizing Production of Artemisinin Derivative Artemether (Anti-Malarial Drug) Through Cunninghamella echinulata var elegans at 5 L Bioreactor Level

2019 ◽  
Vol 15 (4) ◽  
pp. 442-452
Author(s):  
Kashyap Kumar Dubey ◽  
Punit Kumar
Keyword(s):  
Experimental Finding ◽  
Culture Broth ◽  
Quadratic Model ◽  
Optimum Conditions ◽  
Reverse Phase Hplc ◽  
Polar Solvents ◽  
Reverse Phase ◽  
Experimental Conditions ◽  
Cunninghamella Echinulata ◽  
Life Threatening

Background: Malaria is one of the life threatening diseases which is caused by Plasmodium sp. of protozoa and uses Anopheles mosquitos as vector. Plasmodium vivax and Plasmodium falciparum are common form of malaria parasite. Artemisinin is reported for its antimalarial activities and Artemether which is a methyl ether derivative of Artemisinin, has been found effective against P. falciparum. Methods: In the present study, bioconversion of Artemisinin into Artemether was carried out experimentally and the statistical tools like experimental factorial design and Response Surface Methodology were used to find optimal conditions (concentration of Artemisinin, age of inoculum, temperature & pH) using Cunninghamella echinulata var. elegans. Experimental conditions for maximum product recovery from culture broth were also optimized using various polar and non-polar solvents for extraction. Artemether purity was analyzed by reverse-phase HPLC. Experimental data was fitted in a quadratic model and effect of various parameters was analyzed. Results: It was found that bioconversion of Artemisinin into Artemether is growth associated process. It was observed that molasses used as carbon source supported production of Artemether to 3.4g/L. The biomass and oxygen are key element affecting of bioconversion of Artemisinin into Artemether such as higher dissolved oxygen reduced the Artemether bioconversion. The highest bioconversion of Artemisinin into Artemether was obtained at temperature 25.5oC, 5g/L concentration of Artemisinin, at age of inoculum of 44.5 h and at pH 6.0. Model suggested the highest bioconversion of Artemisinin into Artemether was 54% at shake flask level which was near about experimental finding. An optimal condition for bioconversion was also analyzed and 64% bioconversion was obtained in 5L bioreactor. Conclusion: The outcomes of the study provided optimum conditions for bioconversion of Artemisinin into Artemether.

Telemedicine-guided point-of-care ultrasound can be feasible and effective in a life-threatening situation: The case of a field hospital during the COVID-19 pandemic (Preprint)

2020 ◽  
Author(s):  
Tarso Accorsi ◽  
Karine De Amicis Lima ◽  
Alexandra Brigido ◽  
Deborah Belfort ◽  
Fabio Habrum ◽  
...  
Keyword(s):  
Point Of Care ◽  
Image Interpretation ◽  
Acquisition Time ◽  
Point Of Care Ultrasound ◽  
Field Hospital ◽  
Portable Ultrasound ◽  
Local Staff ◽  
Assessment Protocol ◽  
Life Threatening ◽  
Threatening Situation

BACKGROUND Lightweight portable ultrasound is widely available, especially in inaccessible geographical areas. It demonstrates effectiveness and diagnosis improvement even in field conditions but no precise information about protocols, acquisition time, image interpretation, and the relevance in changing medical conduct exists. The COVID-19 pandemic implied many severe cases and the rapid construction of field hospitals with massive general practitioner (GP) recruitment. OBJECTIVE This prospective and descriptive study aimed to evaluate the feasibility of telemedicine guidance using a standardized multi-organ sonographic assessment protocol in untrained GPs during a COVID-19 emergency in a field hospital. METHODS Eleven COVID-19 in-patients presenting life-threatening complications, attended by local staff who spontaneously requested on-time teleconsultation, were enrolled. All untrained doctors successfully positioned the transducer and obtained key images guided by a remote doctor via telemedicine, with remote interpretation of the findings. RESULTS Only four (36%) general practitioners obtained the appropriate key heart image on the left parasternal long axis window, and three (27%) had an image interpreted remotely on-time. The evaluation time ranged from seven to 42 minutes, with a mean of 22.7 + 12. CONCLUSIONS Telemedicine is effective in guiding GPs to perform portable ultrasound in life-threatening situations, showing effectiveness in conducting decisions.

Surgical resection of locally recurrent cervical cancer: a single institutional 70 patient series

2004 ◽  
Vol 14 (5) ◽  
pp. 846-851 ◽  
Author(s):  
V. Moutardier ◽  
G. Houvenaeghel ◽  
M. Martino ◽  
B. Lelong ◽  
V. J. Bardou ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Local Control ◽  
Cancer Recurrence ◽  
Palliative Surgery ◽  
Morbidity Rate ◽  
Actuarial Survival ◽  
Recurrent Cervical Cancer ◽  
Actuarial Survival Rate ◽  
Life Threatening ◽  
Threatening Situation

Pelvic recurrence of cervical cancer is a life-threatening situation and only local control can provide hope for remission. The aim of this study was to evaluate the role of surgery in the treatment of cervical cancer recurrence. This retrospective study analyzed a series of 70 patients who underwent resection of cervix locoregional recurrence. Thirteen patients had palliative salvage surgery for pelvic complications. Twenty-nine resections were considered as curative. Fifty recurrences required pelvic exenterations. The hospital mortality rate was 9% and the morbidity rate was 44%. Overall 5-year actuarial survival rate was 23%. Survival was significantly higher: (a) after curative resection and (b) after centropelvic recurrence resection. Local control was obtained in 48% of the cases and 13 patients are alive with a median follow-up of 75 months. In conclusion, the results of this small and heterogen series seem to justify an attempt to resection for centropelvic recurrences whenever possible. Palliative surgery should be reserved to salvage therapy and highly selected patients.

Ventricular Arrhythmias in Long Term LVAD Patients - Life Threatening Situation or Nothing to Worry About?

2017 ◽  
Vol 36 (4) ◽  
pp. S432 ◽  
Author(s):  
J.G. Jungschleger ◽  
M.M. Mydin ◽  
A. Woods ◽  
M. Urban ◽  
N. Robinson ◽  
...  
Keyword(s):  
Ventricular Arrhythmias ◽  
Life Threatening ◽  
Threatening Situation

Relation between QT interval variability and muscle sympathetic nerve activity in normal subjects

2015 ◽  
Vol 309 (7) ◽  
pp. H1218-H1224 ◽  
Author(s):  
Fatima El-Hamad ◽  
Elisabeth Lambert ◽  
Derek Abbott ◽  
Mathias Baumert
Keyword(s):  
Supine Position ◽  
Sympathetic Nerve ◽  
Qt Interval ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Low Frequency ◽  
Normal Subjects ◽  
Nerve Activity ◽  
Head Up Tilt ◽  
Low Frequency Power

Beat-to-beat variability of the QT interval (QTV) is sought to provide an indirect noninvasive measure of sympathetic nerve activity, but a formal quantification of this relationship has not been provided. In this study we used power contribution analysis to study the relationship between QTV and muscle sympathetic nerve activity (MSNA). ECG and MSNA were recorded in 10 healthy subjects in the supine position and after 40° head-up tilt. Power spectrum analysis was performed using a linear autoregressive model with two external inputs: heart period (RR interval) variability (RRV) and MSNA. Total and low-frequency power of QTV was decomposed into contributions by RRV, MSNA, and sources independent of RRV and MSNA. Results show that the percentage of MSNA power contribution to QT is very small and does not change with tilt. RRV power contribution to QT power is notable and decreases with tilt, while the greatest percentage of QTV is independent of RRV and MSNA in the supine position and after 40° head-up tilt. In conclusion, beat-to-beat QTV in normal subjects does not appear to be significantly affected by the rhythmic modulations in MSNA following low to moderate orthostatic stimulation. Therefore, MSNA oscillations may not represent a useful surrogate for cardiac sympathetic nerve activity at moderate levels of activation, or, alternatively, sympathetic influences on QTV are complex and not quantifiable with linear shift-invariant autoregressive models.

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