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Fava de Lima F, Siqueira de Nóbrega R, Cesare Biselli PJ, Takachi Moriya H. Central venous pressure waveform analysis during sleep/rest: a novel approach to enhance intensive care unit post-extubation monitoring of extubation failure. J Clin Monit Comput 2024:10.1007/s10877-024-01171-0. [PMID: 38954170 DOI: 10.1007/s10877-024-01171-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 04/25/2024] [Indexed: 07/04/2024]
Abstract
This pilot study aimed to investigate the relation between cardio-respiratory parameters derived from Central Venous Pressure (CVP) waveform and Extubation Failure (EF) in mechanically ventilated ICU patients during post-extubation period. This study also proposes a new methodology for analysing these parameters during rest/sleep periods to try to improve the identification of EF. We conducted a prospective observational study, computing CVP-derived parameters including breathing effort, spectral analyses, and entropy in twenty critically ill patients post-extubation. The Dynamic Warping Index (DWi) was calculated from the respiratory component extracted from the CVP signal to identify rest/sleep states. The obtained parameters from EF patients and patients without EF were compared both during arbitrary periods and during reduced DWi (rest/sleep). We have analysed data from twenty patients of which nine experienced EF. Our findings may suggest significantly increased respiratory effort in EF patients compared to those successfully extubated. Our study also suggests the occurrence of significant change in the frequency dispersion of the cardiac signal component. We also identified a possible improvement in the differentiation between the two groups of patients when assessed during rest/sleep states. Although with caveats regarding the sample size, the results of this pilot study may suggest that CVP-derived cardio-respiratory parameters are valuable for monitoring respiratory failure during post-extubation, which could aid in managing non-invasive interventions and possibly reduce the incidence of EF. Our findings also indicate the possible importance of considering sleep/rest state when assessing cardio-respiratory parameters, which could enhance respiratory failure detection/monitoring.
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Affiliation(s)
- Felipe Fava de Lima
- Biomedical Engineering Laboratory, Escola Politécnica, University of São Paulo (USP), São Paulo, Brazil.
| | | | | | - Henrique Takachi Moriya
- Biomedical Engineering Laboratory, Escola Politécnica, University of São Paulo (USP), São Paulo, Brazil
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Adar O, Hollander A, Ilan Y. The Constrained Disorder Principle Accounts for the Variability That Characterizes Breathing: A Method for Treating Chronic Respiratory Diseases and Improving Mechanical Ventilation. Adv Respir Med 2023; 91:350-367. [PMID: 37736974 PMCID: PMC10514877 DOI: 10.3390/arm91050028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/23/2023]
Abstract
Variability characterizes breathing, cellular respiration, and the underlying quantum effects. Variability serves as a mechanism for coping with changing environments; however, this hypothesis does not explain why many of the variable phenomena of respiration manifest randomness. According to the constrained disorder principle (CDP), living organisms are defined by their inherent disorder bounded by variable boundaries. The present paper describes the mechanisms of breathing and cellular respiration, focusing on their inherent variability. It defines how the CDP accounts for the variability and randomness in breathing and respiration. It also provides a scheme for the potential role of respiration variability in the energy balance in biological systems. The paper describes the option of using CDP-based artificial intelligence platforms to augment the respiratory process's efficiency, correct malfunctions, and treat disorders associated with the respiratory system.
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Affiliation(s)
- Ofek Adar
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
| | - Adi Hollander
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
| | - Yaron Ilan
- Faculty of Medicine, Hebrew University, Jerusalem P.O. Box 1200, Israel; (O.A.); (A.H.)
- Department of Medicine, Hadassah Medical Center, Jerusalem P.O. Box 1200, Israel
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Kohlbrenner D, Marillier M, Randy H, Ghaith A, Furian M, Vergès S. Characterisation of the acute hypoxic response using breathing variability parameters: a pilot study in humans. Respir Physiol Neurobiol 2023:104096. [PMID: 37355056 DOI: 10.1016/j.resp.2023.104096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 06/26/2023]
Abstract
PURPOSE We aimed to investigate respiratory rate variability (RRV) and tidal volume (Vt) variability during exposure to normobaric hypoxia (i.e., reduction in the fraction of inspired oxygen - FiO2), and the association of the changes in RRV and Vt variability with the changes in pulse oxygen saturation (SpO2). METHODS Thirty healthy human participants (15 females) were exposed to: (1) 15-min normoxia, (2) 10-min hypoxia simulating 2200m, (3) 10-min hypoxia simulating 4000m, (4) 10-min hypoxia simulating 5000m, (5) 15-min recovery in normoxia. Linear regression modelling was applied with SpO2 (dependent variable) and the changes in RRV and Vt variability (independent variables), controlling for FiO2, age, sex, changes in heart rate (HR), changes in HR variability (HRV), and changes in minute ventilation (VE). RESULTS When modelling breathing parameter variability as root-mean-square standard deviation (RMSSD), a significant independent association of the changes in RRV with the changes in SpO2 was found (B=-4.3e-04, 95% CI=-8.3e-04/-2.1e-05, p=0.04). The changes in Vt variability showed no significant association with the changes in SpO2 (B=-1.6, 95% CI=-5.5/2.4, p=0.42). When modelling parameters variability as SD, a significant independent association of the changes in RRV with the changes in SpO2 was found (B=-8.2e-04, 95% CI=-1.5e-03/-9.4e-05, p=0.03). The changes in Vt variability showed no significant association with the changes in SpO2 (B=1.4, 95% CI=-5.8/8.6, p=0.69). CONCLUSION Higher RRV is independently associated with lower SpO2 during acute hypoxic exposure, while Vt variability parameters are not. Therefore, RRV may be a potentially interesting parameter to characterize individual responses to acute hypoxia.
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Affiliation(s)
- Dario Kohlbrenner
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France; Faculty of Medicine, University of Zurich, Zurich, Switzerland; Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland.
| | | | - Hugo Randy
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
| | - Abdallah Ghaith
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
| | - Michael Furian
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
| | - Samuel Vergès
- HP2 Laboratory, INSERM, Grenoble Alpes University, Grenoble, France
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Doufas AG, Tian L, Kutscher S, Finnsson E, Ágústsson JS, Chung BI, Panousis P. The effect of hyperoxia on ventilation during recovery from general anesthesia: A randomized pilot study for a parallel randomized controlled trial. J Clin Anesth 2022; 83:110982. [PMID: 36265267 DOI: 10.1016/j.jclinane.2022.110982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/29/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022]
Abstract
STUDY OBJECTIVE While supplemental O2 inhalation corrects hypoxemia, its effect on post-anesthesia ventilation remains unknown. This pilot trial tested the hypothesis that hyperoxia increases the time spent with a transcutaneous PCO2 (TcPCO2) > 45 mmHg, compared with standard O2 supplementation. DESIGN Single-blinded, parallel two-arm randomized pilot trial. SETTING University hospital. PATIENTS 20 patients undergoing robotic-assisted laparoscopic nephrectomy. MEASUREMENTS After institutional approval and informed consent, patients were randomized to receive O2 titrated to arterial saturation (SpO2): 90-94% (Conservative O2, N =10), or to SpO2 > 96% (Liberal O2, N = 10) for up to 90 min after anesthesia. Continuous TcPCO2, respiratory inductance plethysmography (RIP), and SpO2, were recorded. We calculated the percentage of time at TcPCO2 > 45 mmHg for each patient and compared the two groups using analysis of covariance, adjusting for sex, age, and body mass index. We also estimated the sample size required to detect the between-group difference observed in this pilot trial. RIP signals were used to calculate apnea/hypopnea index (AHI), which was then compared between two groups. MAIN RESULTS The mean percentage of time with a TcPCO2 > 45 mmHg was 80.6% for the Conservative O2 (N=9) and 61.2% for the Liberal O2 (N=10) group [between-group difference of 19.4% (95% CI: -18.7% to 57.6%), P = 0.140]. With an observed effect size of 0.73, we estimated that 30 participants per group are required, to demonstrate this difference with a power of 80% at a two-sided alpha of 5%. Means SpO2 were 94.5% and 99.9% for the Conservative O2 and the Liberal O2 groups, respectively. AHI was significantly higher in the Conservative O2, compared with the Liberal O2 group (median AHI: 16 vs. 3; P = 0.0014). CONCLUSIONS Hyperoxia in the post-anesthesia period reduced the time spent at TcPCO2 > 45 mmHg and significantly decreased AHI, while mean SpO2 ranged inside the a priori defined limits. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT04723433.
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Affiliation(s)
- Anthony G Doufas
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, United States of America; Center for Sleep and Circadian Sciences, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States of America.
| | - Lu Tian
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Scott Kutscher
- Department of Psychiatry and Behavioral Sciences, and Center for Sleep Sciences and Medicine, Stanford University School of Medicine, Stanford, CA, United States of America
| | | | | | - Benjamin I Chung
- Department of Urology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Periklis Panousis
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, United States of America
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Abstract
Breathing is a vital rhythmic motor behavior with a surprisingly broad influence on the brain and body. The apparent simplicity of breathing belies a complex neural control system, the breathing central pattern generator (bCPG), that exhibits diverse operational modes to regulate gas exchange and coordinate breathing with an array of behaviors. In this review, we focus on selected advances in our understanding of the bCPG. At the core of the bCPG is the preBötzinger complex (preBötC), which drives inspiratory rhythm via an unexpectedly sophisticated emergent mechanism. Synchronization dynamics underlying preBötC rhythmogenesis imbue the system with robustness and lability. These dynamics are modulated by inputs from throughout the brain and generate rhythmic, patterned activity that is widely distributed. The connectivity and an emerging literature support a link between breathing, emotion, and cognition that is becoming experimentally tractable. These advances bring great potential for elucidating function and dysfunction in breathing and other mammalian neural circuits.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
| | - Kaiwen Kam
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | | | - Jack L Feldman
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, California, USA;
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Balogh AL, Sudy R, Petak F, Habre W, Dos Santos Rocha A. Sevoflurane and Hypercapnia Blunt the Physiological Variability of Spontaneous Breathing: A Comparative Interventional Study. Front Physiol 2022; 13:871070. [PMID: 35480042 PMCID: PMC9035625 DOI: 10.3389/fphys.2022.871070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Although spontaneous breathing is known to exhibit substantial physiological fluctuation that contributes to alveolar recruitment, changes in the variability of the respiratory pattern following inhalation of carbon dioxide (CO2) and volatile anesthetics have not been characterized. Therefore, we aimed at comparing the indices of breathing variability under wakefulness, sleep, hypercapnia and sedative and anesthetic concentrations of sevoflurane.Methods: Spontaneous breathing pattern was recorded on two consecutive days in six rabbits using open whole-body plethysmography under wakefulness and spontaneous sleep and following inhalation of 5% CO2, 2% sevoflurane (0.5 MAC) and 4% (1 MAC) sevoflurane. Tidal volume (VT), respiratory rate (RR), minute ventilation (MV), inspiratory time (TI) and mean inspiratory flow (VT/TI) were calculated from the pressure fluctuations in the plethysmograph. Means and coefficients of variation were calculated for each measured variable. Autoregressive model fitting was applied to estimate the relative contributions of random, correlated, and oscillatory behavior to the total variance.Results: Physiological sleep decreased MV by lowering RR without affecting VT. Hypercapnia increased MV by elevating VT. Sedative and anesthetic concentrations of sevoflurane increased VT but decreased MV due to a decrease in RR. Compared to the awake stage, CO2 had no effect on VT/TI while sevoflurane depressed significantly the mean inspiratory flow. Compared to wakefulness, the variability in VT, RR, MV, TI and VT/TI were not affected by sleep but were all significantly decreased by CO2 and sevoflurane. The variance of TI originating from correlated behavior was significantly decreased by both concentrations of sevoflurane compared to the awake and asleep conditions.Conclusions: The variability of spontaneous breathing during physiological sleep and sevoflurane-induced anesthesia differed fundamentally, with the volatile agent diminishing markedly the fluctuations in respiratory volume, inspiratory airflow and breathing frequency. These findings may suggest the increased risk of lung derecruitment during procedures under sevoflurane in which spontaneous breathing is maintained.
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Affiliation(s)
- Adam L. Balogh
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
- *Correspondence: Adam L. Balogh,
| | - Roberta Sudy
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Ferenc Petak
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Walid Habre
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Andre Dos Santos Rocha
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
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Taxini CL, Marques DA, Bícego KC, Gargaglioni LH. A5 noradrenergic neurons and breathing control in neonate rats. Pflugers Arch 2021; 473:859-872. [PMID: 33855632 DOI: 10.1007/s00424-021-02550-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 02/16/2021] [Accepted: 02/25/2021] [Indexed: 10/21/2022]
Abstract
The pontine A5 noradrenergic group contributes to the maturation of the respiratory system before birth in rats. These neurons are connected to the neural network responsible for respiratory rhythmogenesis. In the present study, we investigated the participation of A5 noradrenergic neurons in neonates (P7-8 and P14-15) in the control of ventilation during hypoxia and hypercapnia in in vivo experiments using conjugated saporin anti-dopamine beta-hydroxylase (DβH-SAP) to specifically ablate noradrenergic neurons. Thus, DβH-SAP (420 ng/μL) or saporin (SAP, control) was injected into the A5 region of neonatal male Wistar rats. Hypoxia reduced respiratory variability in control animals; however, A5 lesion prevented this effect in P7-8 rats. Our data suggest that noradrenergic neurons of the A5 region in neonate rats do not participate in the control of ventilation under baseline and hypercapnic conditions, but exert an inhibitory modulation on breathing variability under hypoxic challenge in early life (P7-8).
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Affiliation(s)
- Camila L Taxini
- Department of Morphology and Animal Physiology - FCAV, São Paulo State University (UNESP), Via de acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-900, Brazil
| | - Danuzia A Marques
- Department of Pediatrics, Centre de Recherche de L'Institut Universitaire de Cardiologie Et de Pneumologie de Québec, Université Laval, Québec, G1V 4G5, Canada
| | - Kênia C Bícego
- Department of Morphology and Animal Physiology - FCAV, São Paulo State University (UNESP), Via de acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-900, Brazil
| | - Luciane H Gargaglioni
- Department of Morphology and Animal Physiology - FCAV, São Paulo State University (UNESP), Via de acesso Paulo Donato Castellane s/n, Jaboticabal, SP, 14870-900, Brazil.
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Young BP, Loparo KA, Dick TE, Jacono FJ. Ventilatory pattern variability as a biometric for severity of acute lung injury in rats. Respir Physiol Neurobiol 2019; 265:161-171. [PMID: 30928542 PMCID: PMC9994622 DOI: 10.1016/j.resp.2019.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 03/05/2019] [Accepted: 03/26/2019] [Indexed: 01/27/2023]
Abstract
We hypothesize that ventilatory pattern variability (VPV) varies with the magnitude of acute lung injury (ALI). In adult male rats, we instilled a low- or high- dose of bleomycin or saline (PBS) intratracheally. While representative samples of pulmonary tissue indicated graded lung injury, coefficient of variation (CV) of TTOT did not differ among the 3 groups. Broncho-alveolar lavage fluid (BALF), respiratory rate (fR), mutual information were greater in ALI than sham rats; but did not differ between bleomycin doses. However, nonlinear complexity index (NLCI), which is the difference in sample entropy between original and surrogate data sets was greater for high- versus low- dose; but did not differ between low-dose and sham groups. Further, NLCI correlated to an injury index based on protein concentration of BALF and failure to gain weight. Finally, Receiver Operator Curves (ROCs) indicated that both mutual information and NLCI had greater sensitivity and specificity than fR and CVTTOT in identifying ALI. Thus, nonlinear analyses of VPV can distinguish ALI and out performs fR as a biometric.
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Affiliation(s)
- Benjamin P Young
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kenneth A Loparo
- Department of Electrical Engineering and Computer Science, School of Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Thomas E Dick
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Neurosciences, School of Medicine Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Frank J Jacono
- Division of Pulmonary, Critical Care, & Sleep Medicine, Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Louis Stokes VA Medical Center, Cleveland, OH 44106, USA
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Satalin J, Habashi NM, Nieman GF. Never give the lung the opportunity to collapse. TRENDS IN ANAESTHESIA AND CRITICAL CARE 2018. [DOI: 10.1016/j.tacc.2018.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Fouzas S, Theodorakopoulos I, Delgado-Eckert E, Latzin P, Frey U. Breath-to-breath variability of exhaled CO2 as a marker of lung dysmaturity in infancy. J Appl Physiol (1985) 2017; 123:1563-1570. [DOI: 10.1152/japplphysiol.00372.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The concept of diffusional screening implies that breath-to-breath variations in CO2 clearance, when related to the variability of breathing, may contain information on the quality and utilization of the available alveolar surface. We explored the validity of the above hypothesis in a cohort of young infants of comparable postmenstrual age but born at different stages of lung maturity, namely, in term-born infants ( n = 128), preterm-born infants without chronic lung disease of infancy (CLDI; n = 53), and preterm infants with moderate/severe CLDI ( n = 87). Exhaled CO2 volume (VE,CO2) and concentration (FE,CO2) were determined by volumetric capnography, whereas their variance was assessed by linear and nonlinear variability metrics. The relationship between relative breath-to-breath change of VE,CO2 (ΔVE,CO2) and the corresponding change of tidal volume (ΔVT) was also analyzed. Nonlinear FE,CO2 variability was lower in CLDI compared with term and non-CLDI preterm group ( P < 0.001 for both comparisons). In CLDI infants, most of the VE,CO2 variability was attributed to the variability of VT ( r2 = 0.749), whereas in term and healthy preterm infants this relationship was weaker ( r2 = 0.507 and 0.630, respectively). The ΔVE,CO2 − ΔVT slope was less steep in the CLDI group (1.06 ± 0.07) compared with non-CLDI preterm (1.16 ± 0.07; P < 0.001) and term infants (1.20 ± 0.10; P < 0.001), suggesting that the more dysmature the infant lung, the less efficiently it eliminates CO2 under tidal breathing conditions. We conclude that the temporal variation of CO2 clearance may be related to the degree of lung dysmaturity in early infancy. NEW & NOTEWORTHY Young infants exhibit appreciable breath-to-breath CO2 variability that can be quantified by nonlinear variability metrics and may reflect the degree of lung dysmaturity. In infants with moderate/severe chronic lung disease of infancy (CLDI), the variability of the exhaled CO2 is mainly driven by the variability of breathing, whereas in term-born and healthy preterm infants this relationship is less strong. The slope of the relative CO2-to-volume change is less steep in CLDI infants, suggesting that dysmature lungs are less efficient in eliminating CO2 under tidal breathing conditions.
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Affiliation(s)
- Sotirios Fouzas
- Pediatric Respiratory Unit, University General Hospital of Patras, Patras, Greece
| | | | - Edgar Delgado-Eckert
- Computational Physiology and Biostatistics, University of Basel Children’s Hospital, Basel, Switzerland
| | - Philipp Latzin
- Pediatric Respiratory Medicine, University Children’s Hospital Bern (Inselspital), University of Bern, Bern, Switzerland
| | - Urs Frey
- Division of Pulmonology and Respiratory Research Group, University Children’s Hospital Basel, Basel, Switzerland
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Shalish W, Kanbar LJ, Rao S, Robles-Rubio CA, Kovacs L, Chawla S, Keszler M, Precup D, Brown K, Kearney RE, Sant'Anna GM. Prediction of Extubation readiness in extremely preterm infants by the automated analysis of cardiorespiratory behavior: study protocol. BMC Pediatr 2017; 17:167. [PMID: 28716018 PMCID: PMC5512825 DOI: 10.1186/s12887-017-0911-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/29/2017] [Indexed: 11/10/2022] Open
Abstract
Background Extremely preterm infants (≤ 28 weeks gestation) commonly require endotracheal intubation and mechanical ventilation (MV) to maintain adequate oxygenation and gas exchange. Given that MV is independently associated with important adverse outcomes, efforts should be made to limit its duration. However, current methods for determining extubation readiness are inaccurate and a significant number of infants fail extubation and require reintubation, an intervention that may be associated with increased morbidities. A variety of objective measures have been proposed to better define the optimal time for extubation, but none have proven clinically useful. In a pilot study, investigators from this group have shown promising results from sophisticated, automated analyses of cardiorespiratory signals as a predictor of extubation readiness. The aim of this study is to develop an automated predictor of extubation readiness using a combination of clinical tools along with novel and automated measures of cardiorespiratory behavior, to assist clinicians in determining when extremely preterm infants are ready for extubation. Methods In this prospective, multicenter observational study, cardiorespiratory signals will be recorded from 250 eligible extremely preterm infants with birth weights ≤1250 g immediately prior to their first planned extubation. Automated signal analysis algorithms will compute a variety of metrics for each infant, and machine learning methods will then be used to find the optimal combination of these metrics together with clinical variables that provide the best overall prediction of extubation readiness. Using these results, investigators will develop an Automated system for Prediction of EXtubation (APEX) readiness that will integrate the software for data acquisition, signal analysis, and outcome prediction into a single application suitable for use by medical personnel in the neonatal intensive care unit. The performance of APEX will later be prospectively validated in 50 additional infants. Discussion The results of this research will provide the quantitative evidence needed to assist clinicians in determining when to extubate a preterm infant with the highest probability of success, and could produce significant improvements in extubation outcomes in this population. Trial registration Clinicaltrials.gov identifier: NCT01909947. Registered on July 17 2013. Trial sponsor: Canadian Institutes of Health Research (CIHR). Electronic supplementary material The online version of this article (doi:10.1186/s12887-017-0911-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wissam Shalish
- Department of Pediatrics, Division of Neonatology, Montreal Children's Hospital, McGill University, 1001 Boul. Décarie, room B05.2714. Montreal, Quebec, H4A 3J1, Canada
| | - Lara J Kanbar
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Smita Rao
- Department of Pediatrics, Division of Neonatology, Montreal Children's Hospital, McGill University, 1001 Boul. Décarie, room B05.2714. Montreal, Quebec, H4A 3J1, Canada
| | - Carlos A Robles-Rubio
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Lajos Kovacs
- Department of Neonatology, Jewish General Hospital, Montreal, Quebec, H3T 1E2, Canada
| | - Sanjay Chawla
- Division of Neonatal-Perinatal Medicine, Hutzel Women's Hospital, Wayne State University, Detroit, MI, 48201, USA
| | - Martin Keszler
- Department of Pediatrics, Women and Infants Hospital of Rhode Island, Brown University, Providence, RI, 02905, USA
| | - Doina Precup
- Department of Computer Science, McGill University, Montreal, Quebec, H3A 0E9, Canada
| | - Karen Brown
- Department of Anesthesia, Montreal Children's Hospital, McGill University Health Center, Montreal, Quebec, H4A 3J1, Canada
| | - Robert E Kearney
- Department of Biomedical Engineering, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Guilherme M Sant'Anna
- Department of Pediatrics, Division of Neonatology, Montreal Children's Hospital, McGill University, 1001 Boul. Décarie, room B05.2714. Montreal, Quebec, H4A 3J1, Canada.
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12
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BuSha BF, Banis G. A stochastic and integrative model of breathing. Respir Physiol Neurobiol 2017; 237:51-56. [DOI: 10.1016/j.resp.2016.12.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/21/2016] [Accepted: 12/28/2016] [Indexed: 12/17/2022]
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13
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Goto Y, Katayama S, Shono A, Mori Y, Miyazaki Y, Sato Y, Ozaki M, Kotani T. Roles of neurally adjusted ventilatory assist in improving gas exchange in a severe acute respiratory distress syndrome patient after weaning from extracorporeal membrane oxygenation: a case report. J Intensive Care 2016; 4:26. [PMID: 27057312 PMCID: PMC4823850 DOI: 10.1186/s40560-016-0153-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/31/2016] [Indexed: 02/06/2023] Open
Abstract
Background Patient-ventilator asynchrony is a major cause of difficult weaning from mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) is reported useful to improve the synchrony in patients with sustained low lung compliance. However, the role of NAVA has not been fully investigated. Case presentation The patient was a 63-year-old Japanese man with acute respiratory distress syndrome secondary to respiratory infection. He was treated with extracorporeal membrane oxygenation for 7 days and survived. Dynamic compliance at withdrawal of extracorporeal membrane oxygenation decreased to 20 ml/cmH2O or less, but gas exchange was maintained by full support with assist/control mode. However, weaning from mechanical ventilation using a flow trigger failed repeatedly because of patient-ventilator asynchrony with hypercapnic acidosis during partial ventilator support despite using different types of ventilators and different trigger levels. Weaning using NAVA restored the regular respiration and stable and normal acid-base balance. Electromyographic analysis of the diaphragm clearly showed improved triggering of both the start and the end of spontaneous inspiration. Regional ventilation monitoring using electrical impedance tomography showed an increase in tidal volume and a ventilation shift to the dorsal regions during NAVA, indicating that NAVA could deliver gas flow to the dorsal regions to adjust for the magnitude of diaphragmatic excursion. NAVA was applied for 31 days, followed by partial ventilatory support with a conventional flow trigger. The patient was discharged from the intensive care unit on day 110 and has recovered enough to be able to live without a ventilatory support for 5 h per day. Conclusion Our experience showed that NAVA improved not only patient-ventilator synchrony but also regional ventilation distribution in an acute respiratory distress patient with sustained low lung compliance.
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Affiliation(s)
- Yuya Goto
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Shinshu Katayama
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Atsuko Shono
- Department of Anesthesiology, Shimane University, Shimane, 693-8501 Japan
| | - Yosuke Mori
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Yuya Miyazaki
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Yoko Sato
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Makoto Ozaki
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Toru Kotani
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
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Ranohavimparany A, Bautin N, Fiamma MN, Similowski T, Straus C. Source of ventilatory complexity in the postmetamorphic tadpole brainstem, Pelophylax ridibundus: A pharmacological study. Respir Physiol Neurobiol 2016; 224:27-36. [DOI: 10.1016/j.resp.2014.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/22/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022]
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15
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Schmidt M, Cecchini J, Kindler F, Similowski T, Demoule A. Variabilité ventilatoire et assistance ventilatoire en réanimation. MEDECINE INTENSIVE REANIMATION 2014. [DOI: 10.1007/s13546-014-0843-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Tobin MJ, Laghi F, Jubran A. Ventilatory failure, ventilator support, and ventilator weaning. Compr Physiol 2013; 2:2871-921. [PMID: 23720268 DOI: 10.1002/cphy.c110030] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The development of acute ventilatory failure represents an inability of the respiratory control system to maintain a level of respiratory motor output to cope with the metabolic demands of the body. The level of respiratory motor output is also the main determinant of the degree of respiratory distress experienced by such patients. As ventilatory failure progresses and patient distress increases, mechanical ventilation is instituted to help the respiratory muscles cope with the heightened workload. While a patient is connected to a ventilator, a physician's ability to align the rhythm of the machine with the rhythm of the patient's respiratory centers becomes the primary determinant of the level of rest accorded to the respiratory muscles. Problems of alignment are manifested as failure to trigger, double triggering, an inflationary gas-flow that fails to match inspiratory demands, and an inflation phase that persists after a patient's respiratory centers have switched to expiration. With recovery from disorders that precipitated the initial bout of acute ventilatory failure, attempts are made to discontinue the ventilator (weaning). About 20% of weaning attempts fail, ultimately, because the respiratory controller is unable to sustain ventilation and this failure is signaled by development of rapid shallow breathing. Substantial advances in the medical management of acute ventilatory failure that requires ventilator assistance are most likely to result from research yielding novel insights into the operation of the respiratory control system.
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Affiliation(s)
- Martin J Tobin
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Affairs Hospital and Loyola University of Chicago Stritch School of Medicine, Hines, Illinois, USA.
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18
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Control of ventilation in COPD and lung injury. Respir Physiol Neurobiol 2013; 189:371-6. [PMID: 23856486 DOI: 10.1016/j.resp.2013.07.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 06/27/2013] [Accepted: 07/04/2013] [Indexed: 11/23/2022]
Abstract
Breathing occurs in single breaths and in patterns which are altered by the onset, progression and resolution of respiratory diseases. Through modulations of rate, depth, and patterning of breathing, the ventilatory control system maintains numerous critical variables within their homeostatic ranges. A dynamic respiratory control system is critical to successful adaptation in the face of progressive pulmonary pathology. The objective of this review, is to illustrate functional changes and compensatory mechanisms which occur with the onset and progression of acute and chronic lung disease. Chronic obstructive pulmonary disease (COPD) will be considered as a model of a slowly progressive pulmonary process, where destruction of lung parenchyma and airway obstruction leads to hypoxemia and hypercapnia. Over time, adaptations of the respiratory control system to this disease include changes in the intrinsic properties of respiratory muscles, chemoreceptor signaling, and central respiratory drive which increase motor output to the respiratory muscles. In contrast, acute respiratory distress syndrome (ARDS) is an exemplar of an acute pulmonary process. The result of severe lung injury, ARDS is characterized by lung infiltrates, rapidly progressive hypoxemic respiratory failure, and possible progression to pulmonary fibrosis. Changes in breathing patterns result from these functional changes, as well as altered processing of afferent feedback by the central controller, possibly influenced by brainstem inflammation. Taken together, these disease models highlight the plasticity of the respiratory control system in response to the development and progression of lung disease.
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Latshang TD, Turk AJ, Hess T, Schoch OD, Bosch MM, Barthelmes D, Merz TM, Hefti U, Hefti JP, Maggiorini M, Bloch KE. Acclimatization improves submaximal exercise economy at 5533 m. Scand J Med Sci Sports 2011; 23:458-67. [PMID: 22093058 DOI: 10.1111/j.1600-0838.2011.01403.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2011] [Indexed: 11/28/2022]
Abstract
We tested whether the better subjective exercise tolerance perceived by mountaineers after altitude acclimatization relates to enhanced exercise economy. Thirty-two mountaineers performed progressive bicycle exercise to exhaustion at 490 m and twice at 5533 m (days 6-7 and day 11), respectively, during an expedition to Mt. Muztagh Ata. Maximal work rate (W(max)) decreased from mean ± SD 356 ± 73 watts at 490 m to 191 ± 49 watts and 193 ± 45 watts at 5533 m, days 6-7 and day 11, respectively; corresponding maximal oxygen uptakes (VO2max ) were 50.7 ± 9.5, 26.3 ± 5.6, 24.7 ± 7.0 mL/min/kg (P = 0.0001 5533 m vs 490 m). On days 6-7 (5533 m), VO(2) at 75% W(max) (152 ± 37 watts) was 1.75 ± 0.45 L/min, oxygen saturation 68 ± 8%. On day 11 (5533 m), at the same submaximal work rate, VO(2) was lower (1.61 ± 0.47 L/min, P < 0.027) indicating improved net efficiency; oxygen saturation was higher (74 ± 7%, P < 0.0004) but ratios of VO(2) to work rate increments remained unchanged. On day 11, mountaineers climbed faster from 4497 m to 5533 m than on days 5-6 but perceived less effort (visual analog scale 50 ± 15 vs 57 ± 20, P = 0.006) and reduced symptoms of acute mountain sickness. We conclude that the better performance and subjective exercise tolerance after acclimatization were related to regression of acute mountain sickness and improved submaximal exercise economy because of lower metabolic demands for non-external work-performing functions.
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Affiliation(s)
- T D Latshang
- Pulmonary Division, University Hospital Zurich, Zurich, Switzerland
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20
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Jacono FJ, Mayer CA, Hsieh YH, Wilson CG, Dick TE. Lung and brainstem cytokine levels are associated with breathing pattern changes in a rodent model of acute lung injury. Respir Physiol Neurobiol 2011; 178:429-38. [PMID: 21569869 PMCID: PMC3170447 DOI: 10.1016/j.resp.2011.04.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/22/2011] [Accepted: 04/27/2011] [Indexed: 02/07/2023]
Abstract
Acute lung injury evokes a pulmonary inflammatory response and changes in the breathing pattern. The inflammatory response has a centrally mediated component which depends on the vagi. We hypothesize that the central inflammatory response, complimentary to the pulmonary inflammatory response, is expressed in the nuclei tractus solitarii (nTS) and that the expression of cytokines in the nTS is associated with breathing pattern changes. Adult, male Sprague-Dawley rats (n=12) received intratracheal instillation of either bleomycin (3units in 120μl of saline) or saline (120μl). Respiratory pattern changed by 24h. At 48h, bronchoalveolar lavage fluid and lung tissue had increased IL-1β and TNF-α levels, but not IL-6. No changes in these cytokines were noted in serum. Immunocytochemical analysis of the brainstem indicated increased expression of IL-1β in the nTS commissural subnucleus that was localized to neurons. We conclude that breathing pattern changes in acute lung injury were associated with increased levels of IL-1β in brainstem areas which integrate cardio-respiratory sensory input.
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Affiliation(s)
- Frank J Jacono
- Division of Pulmonary, Critical Care and Sleep Medicine, CWRU School of Medicine and University Hospitals Case Medical Center, United States.
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21
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Nemati S, Edwards BA, Sands SA, Berger PJ, Wellman A, Verghese GC, Malhotra A, Butler JP. Model-based characterization of ventilatory stability using spontaneous breathing. J Appl Physiol (1985) 2011; 111:55-67. [PMID: 21474696 DOI: 10.1152/japplphysiol.01358.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyclic ventilatory instabilities are widely attributed to an increase in the sensitivity or loop gain of the chemoreflex feedback loop controlling ventilation. A major limitation in the conventional characterization of this feedback loop is the need for labor-intensive methodologies. To overcome this limitation, we developed a method based on trivariate autoregressive modeling using ventilation, end-tidal Pco(2) and Po(2); this method provides for estimation of the overall "loop gain" of the respiratory control system and its components, chemoreflex gain and plant gain. Our method was applied to recordings of spontaneous breathing in 15 anesthetized, tracheostomized, newborn lambs before and after administration of domperidone (a dopamine D(2)-receptor antagonist that increases carotid body sensitivity). We quantified the known increase in hypoxic ventilatory sensitivity in response to domperidone; controller gain for O(2) increased from 0.06 (0.03, 0.09) l·min(-1)·mmHg(-1) to 0.09 (0.08, 0.13) l·min(-1)·mmHg(-1); median (interquartile-range). We also report that domperidone increased the loop gain of the control system more than twofold [0.14 (0.12, 0.22) to 0.40 (0.15, 0.57)]. We observed no significant changes in CO(2) controller gain, or plant gains for O(2) and CO(2). Furthermore, our estimate of the cycle duration of periodic breathing compared favorably with that observed experimentally [measured: 7.5 (7.2, 9.1) vs. predicted: 7.9 (7.0, 9.2) breaths]. Our results demonstrate that model-based analysis of spontaneous breathing can 1) characterize the dynamics of the respiratory control system, and 2) provide a simple tool for elucidating an individual's propensity for ventilatory instability, in turn allowing potential therapies to be directed at the underlying mechanisms.
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Affiliation(s)
- Shamim Nemati
- Massachusetts Institute of Technology, Cambridge, MA, USA.
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22
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Lower interbreath interval complexity is associated with extubation failure in mechanically ventilated patients during spontaneous breathing trials. ACTA ACUST UNITED AC 2010; 68:1310-6. [PMID: 20539175 DOI: 10.1097/ta.0b013e3181da90db] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine whether lower complexity of interbreath interval as measured with nonlinear analysis techniques will identify patients who fail to separate from mechanical ventilation after 30-minute spontaneous breathing trials (SBTs). METHODS Respiratory waveforms from SBT of patients in surgical or burn intensive care units were recorded for later analysis. The decision to extubate was made by attending physician. Extubated patients were observed for 48 hours; during this time, reintubation or noninvasive positive pressure ventilation was considered as a failure. Analysis of waveform data by software was performed post hoc. Sample entropy (SampEn) and other nonlinear measures were 48 hours of extubation. RESULTS Thirty-two patients (24 burn, 8 trauma/surgical admissions; mean age, 40.2 +/- 16.9 years; 26 men and 6 women) who were intubated >24 hours were extubated after SBT. Twenty-four patients were successfully separated from mechanical ventilation and eight failed. Age, gender, and mechanism of injury did not influence outcome. SampEn calculated for the two groups presented in this study was different with the cohort that failed extubation having a lower mean value (1.35 +/- 0.39 vs. 1.87 +/- 0.27; p < 0.001). Other nonlinear metrics were moved in concert with SampEn. The stationarity in the respiratory signal was not different between groups. CONCLUSION In intubated patients, the interbreath interval in those who were successfully separated from mechanical ventilation was more irregular than those who failed, as measured by nonlinear techniques. When available at bedside, these metrics may be useful markers of pulmonary health and assist in clinical decision making.
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23
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McKechnie SR, Drummond GB. Cytokines, neurokines or both? Mixed mechanisms of mechanical lung injury. J Physiol 2010; 588:1813-4. [PMID: 20516345 PMCID: PMC2901965 DOI: 10.1113/jphysiol.2010.191478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- S R McKechnie
- Adult Intensive Care Unit, John Radcliffe Hospital, Oxford, UK.
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24
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Papaioannou V, Dragoumanis C, Pneumatikos I. Biosignal analysis techniques for weaning outcome assessment. J Crit Care 2009; 25:39-46. [PMID: 19592203 DOI: 10.1016/j.jcrc.2009.04.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 04/14/2009] [Accepted: 04/28/2009] [Indexed: 11/18/2022]
Abstract
Discontinuation of mechanical ventilation in critically ill patients is a challenging task and involves a careful weighting of the benefits of early extubation and the risks of premature spontaneous breathing trial. Recently, apart from studying different physiological variables by means of descriptive statistical tests, breathing pattern variability analysis has been performed for the assessment of weaning readiness. A limited number of clinical studies implementing different weaning protocols in heterogeneous groups of patients and using a variable set of signal processing techniques have appeared in the critical care literature, with varying results. The purpose of this review article is 3-fold: (1) to describe the different signal processing techniques being implemented for the assessment of weaning readiness, (2) to provide insight into the pathophysiological mechanisms that may govern breath-to-breath variability/complexity in health and disease, and (3) to present results from the critical care literature derived from the application of biosignal analysis tools for the identification of possible weaning indices.
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Affiliation(s)
- Vasilios Papaioannou
- Department of Intensive Care Medicine, Democritus University of Thrace, Alexandroupolis Medical School, 68100 Dragana, Greece.
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25
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Song G, Poon CS. Lateral parabrachial nucleus mediates shortening of expiration and increase of inspiratory drive during hypercapnia. Respir Physiol Neurobiol 2009; 165:9-12. [PMID: 18996229 PMCID: PMC2692991 DOI: 10.1016/j.resp.2008.10.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 09/10/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022]
Abstract
We have previously shown that unilateral or bilateral lesions of the lateral parabrachial nucleus (LPBN) in anesthetized, vagotomized rats markedly and selectively attenuate the shortening of expiratory duration (T(E)) during hypoxia without appreciably affecting all other hypoxic response components. Here, we report that unilateral LPBN lesion by kainic acid in the same group of animals not only abolished normal T(E)-shortening during central chemoreceptors activation by hyperoxic hypercapnia, but led to paradoxical T(E)-prolongation and corresponding decrease of respiratory frequency. Furthermore, LPBN lesion significantly attenuated the increase in phrenic activity during hyperoxic hypercapnia, without appreciably affecting the corresponding shortening of inspiratory duration (T(I)). These findings provide the first evidence indicating that central chemoafferent inputs are organized in parallel and segregated pathways that separately modulate inspiratory drive, T(I), and T(E) in conjunction with similar parallel and segregated central processing of peripheral chemoafferent inputs reported previously [Young, D.L., Eldridge, F.L., Poon, C.S., 2003. Integration-differentiation and gating of carotid afferent traffic that shapes the respiratory pattern. J. Appl. Physiol. 94, 1213-1229].
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Affiliation(s)
- Gang Song
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chi-Sang Poon
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Mangin L, Fiamma MN, Straus C, Derenne JP, Zelter M, Clerici C, Similowski T. Source of human ventilatory chaos: lessons from switching controlled mechanical ventilation to inspiratory pressure support in critically ill patients. Respir Physiol Neurobiol 2008; 161:189-96. [PMID: 18387347 DOI: 10.1016/j.resp.2008.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2007] [Revised: 01/30/2008] [Accepted: 02/08/2008] [Indexed: 11/15/2022]
Abstract
Ventilatory flow measured at the airway opening in humans exhibits a complex dynamics that has the features of chaos. Currently available data point to a neural origin of this feature, but the role of respiratory mechanics has not been specifically assessed. In this aim, we studied 17 critically ill mechanically ventilated patients during a switch form an entirely machine-controlled assistance mode (assist-controlled ventilation ACV) to a patient-driven mode (inspiratory pressure support IPS). Breath-by-breath respiratory variability was assessed with the coefficient of variation of tidal volume, total cycle time, inspiratory time, expiratory time, mean inspiratory flow, duty cycle. The detection of chaos was performed with the noise titration technique. When present, chaos was characterized with numerical indexes (correlation dimension, irregularity; largest Lyapunov exponent, sensitivity to initial conditions). Expectedly, the coefficients of variations of the respiratory variables were higher during IPS than during ACV. During ACV, noise titration failed to detect nonlinearities in 12 patients who did not exhibit signs of spontaneous respiratory activity. This indicates that the mechanical properties of the respiratory system were not sufficient to produce ventilatory chaos in the presence of a nonlinear command (ventilator clock). A positive noise limit was found in the remaining 5 cases, but these patients exhibited signs of active expiratory control (highly variable expiratory time, respiratory frequency higher than the set frequency). A positive noise limit was also observed in 16/17 patients during IPS (p<0.001). These observations suggest that ventilatory chaos predominantly has a neural origin (intrinsic to the respiratory central pattern generators, resulting from their perturbation by respiratory afferents, or both), with little contribution of respiratory mechanics, if any.
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Affiliation(s)
- Laurence Mangin
- Université Paris 7 and Service de Physiologie-Explorations fonctionnelles, Hôpital Bichat, AP-HP, Paris, France.
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27
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Jubran A, Tobin MJ. Noninvasive Respiratory Monitoring. Crit Care Med 2008. [DOI: 10.1016/b978-032304841-5.50015-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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28
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Giraldo BF, Chaparro J, Ballesteros D, Lopez-Rodriguez L, Geat D, Benito S, Caminal P. Study of the respiratory pattern variability in patients during weaning trials. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:3909-12. [PMID: 17271151 DOI: 10.1109/iembs.2004.1404093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mechanical ventilators are used to provide life support in patients with respiratory failure. One of the challenges in intensive care is the process of weaning from mechanical ventilation. We studied the differences in respiratory pattern variability between patients capable of maintaining spontaneous breathing during weaning trials and patients that fail to maintain spontaneous breathing. The respiratory pattern was characterized by the following time series: inspiratory time (T(I)), expiratory time (T(E)), breath duration (T(Tot)), tidal volume (V(T)), fractional inspiratory time (T(I)/T(Tot)), mean inspiratory flow (V(T)/T(I)), respiratory frequency (f), and rapid shallow breathing index (f/V(T)). The variational activity of breathing was partitioned into autoregressive, periodic and white noise fractions. Patients with unsuccessful trial presented a tendency to higher values of gross variability of V(T)/T(I) and f/V(T), and lower values of T(I). The autocorrelation coefficients tended to present higher values for T(I), T(I)/T(Tot) and V(T)/T(I). During both successful and unsuccessful T-tube test uncorrelated random behavior constituted > 75% of the variance of each time breath components and represented 50 to 70% in the breath component related to V(T). Correlated behavior represented 6 to 21% in time components and 28 to 50% in component related to V(T).
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Affiliation(s)
- B F Giraldo
- Biomedical Engineering Research Centre (CREB), Department ESAII, Technical University of Catalonia, Barcelona, Spain
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29
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Fiamma MN, Straus C, Thibault S, Wysocki M, Baconnier P, Similowski T. Effects of hypercapnia and hypocapnia on ventilatory variability and the chaotic dynamics of ventilatory flow in humans. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1985-93. [PMID: 17218438 DOI: 10.1152/ajpregu.00792.2006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In humans, lung ventilation exhibits breath-to-breath variability and dynamics that are nonlinear, complex, sensitive to initial conditions, unpredictable in the long-term, and chaotic. Hypercapnia, as produced by the inhalation of a CO2-enriched gas mixture, stimulates ventilation. Hypocapnia, as produced by mechanical hyperventilation, depresses ventilation in animals and in humans during sleep, but it does not induce apnea in awake humans. This emphasizes the suprapontine influences on ventilatory control. How cortical and subcortical commands interfere thus depend on the prevailing CO2 levels. However, CO2 also influences the variability and complexity of ventilation. This study was designed to describe how this occurs and to test the hypothesis that CO2 chemoreceptors are important determinants of ventilatory dynamics. Spontaneous ventilatory flow was recorded in eight healthy subjects. Breath-by-breath variability was studied through the coefficient of variation of several ventilatory variables. Chaos was assessed with the noise titration method (noise limit) and characterized with numerical indexes [largest Lyapunov exponent (LLE), sensitivity to initial conditions; Kolmogorov-Sinai entropy (KSE), unpredictability; and correlation dimension (CD), irregularity]. In all subjects, under all conditions, a positive noise limit confirmed chaos. Hypercapnia reduced breathing variability, increased LLE ( P = 0.0338 vs. normocapnia; P = 0.0018 vs. hypocapnia), increased KSE, and slightly reduced CD. Hypocapnia increased variability, decreased LLE and KSE, and reduced CD. These results suggest that chemoreceptors exert a strong influence on ventilatory variability and complexity. However, complexity persists in the quasi-absence of automatic drive. Ventilatory variability and complexity could be determined by the interaction between the respiratory central pattern generator and suprapontine structures.
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30
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Wysocki M, Cracco C, Teixeira A, Mercat A, Diehl JL, Lefort Y, Derenne JP, Similowski T. Reduced breathing variability as a predictor of unsuccessful patient separation from mechanical ventilation. Crit Care Med 2006; 34:2076-83. [PMID: 16755257 DOI: 10.1097/01.ccm.0000227175.83575.e9] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To compare descriptors of the breath-to-breath respiratory variability during a 60-min spontaneous breathing trial in patients successfully and unsuccessfully separated from the ventilator and the endotracheal tube and to assess the usefulness of these predictors in discriminating these two categories of patients. DESIGN Prospective observational study. SETTING Four general intensive care units in university hospitals. PATIENTS A total of 51 consecutive patients mechanically ventilated for >24 hrs. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Tidal volume, respiratory period, inspiratory time, expiratory time, mean inspiratory flow (tidal volume/inspiratory time), and duty cycle (inspiratory time/respiratory period) were obtained from the flow signal. Breath-by-breath variability was expressed in terms of their coefficients of variation (CV), the number of breaths among which a significant correlation was found (lag), and the autocorrelation coefficient between one breath and the following one. Five patients were excluded because of nonstationarity of the data, leaving 46 cases for analysis. Between-group comparison was conducted with the Mann-Whitney test, and a nonparametric classification and regression tree was used to identify variables discriminating "success" (n = 32) and "failure" patients (n = 14). All coefficients of variation were significantly higher in success patients, who also exhibited significantly less respiratory autocorrelation (shorter "short memory"). The classification and regression tree analysis allocated all success patients to a group defined by a coefficient of variation of tidal volume/inspiratory time of > or =19% and a coefficient of variation of inspiratory time/respiratory period of > or =10% that did not contain any failure patient. All failure patients belonged to a group with coefficient of variation of tidal volume/inspiratory time of <19%, a lag tidal volume of > or =11, and that contained no success patient. CONCLUSIONS In intensive care unit patients undergoing a spontaneous breathing trial, breathing variability is greater in patients successfully separated from the ventilator and the endotracheal tube. Variability indices are sufficient to separate success from failure cases.
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Affiliation(s)
- Marc Wysocki
- UPRES EA 2397, Université Paris VI Pierre et Marie Curie, Paris, France
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Casaseca-de-la-Higuera P, Martín-Fernández M, Alberola-López C. Weaning From Mechanical Ventilation: A Retrospective Analysis Leading to a Multimodal Perspective. IEEE Trans Biomed Eng 2006; 53:1330-45. [PMID: 16830937 DOI: 10.1109/tbme.2006.873695] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Practitioners' decision for mechanical aid discontinuation is a challenging task that involves a complete knowledge of a great number of clinical parameters, as well as its evolution in time. Recently, an increasing interest on respiratory pattern variability as an extubation readiness indicator has appeared. Reliable assessment of this variability involves a set of signal processing and pattern recognition techniques. This paper presents a suitability analysis of different methods used for breathing pattern complexity assessment. The contribution of this analysis is threefold: 1) to serve as a review of the state of the art on the so-called weaning problem from a signal processing point of view; 2) to provide insight into the applied processing techniques and how they fit into the problem; 3) to propose additional methods and further processing in order to improve breathing pattern regularity assessment and weaning readiness decision. Results on experimental data show that sample entropy outperforms other complexity assessment methods and that multidimensional classification does improve weaning prediction. However, the obtained performance may be objectionable for real clinical practice, a fact that paves the way for a multimodal signal processing framework, including additional high-quality signals and more reliable statistical methods.
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Affiliation(s)
- Pablo Casaseca-de-la-Higuera
- Laboratory of Image Processing, E.T.S. Ingenieros de Telecomunicación, University of Valladolid, 47011 Valladolid, Spain.
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Brack T, Jubran A, Laghi F, Tobin MJ. Fluctuations in end-expiratory lung volume during Cheyne-Stokes respiration. Am J Respir Crit Care Med 2005; 171:1408-13. [PMID: 15778489 DOI: 10.1164/rccm.200503-409oc] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We hypothesized that patients with Cheyne-Stokes respiration exhibit periodic increases in end-expiratory lung volume, mediated by changes in breath components, postinspiratory inspiratory muscle activity, or both. Calibrated inductive plethysmography revealed that 12 of 12 patients with Cheyne-Stokes respiration experienced increases in end-expiratory volume during hyperpnea: maximum 412 +/- 112 (SE) ml (range 75-1,543 ml). Compared with quiet breathing, the breath with largest increase in end-expiratory volume had larger tidal volume (867 +/- 107 vs. 567 +/- 38 ml, p < 0.01) and shorter expiratory time (1.25 +/- 0.11 vs. 1.66 +/- 0.15 seconds, p < 0.05). During decrescendo, the breath with largest decrease in end-expiratory volume had smaller tidal volume (p < 0.01) and longer expiratory time (p < 0.01). Cross-correlation of time series revealed that end-expiratory volume was related to both breath components (p < 0.0001). Bipolar needle electrodes revealed that scalene muscle activity at end-expiration was 50.7 +/- 14.0% higher at highest increase in lung volume than during preceding apnea (p < 0.05). Time series for scalene activity and end-expiratory volume were cross-correlated (p < 0.008). Increase in tonic scalene activity at end-expiration, however, was equivalent during crescendo and decrescendo phases: 50.6 +/- 22.1 versus 42.0 +/- 12.9% (p = 0.48). In conclusion, patients with Cheyne-Stokes respiration exhibit fluctuations in end-expiratory lung volume, primarily because of alterations in tidal volume and expiratory time rather than postinspiratory inspiratory muscle activity.
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Affiliation(s)
- Thomas Brack
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. VA Hospital, 111N, 5th Avenue and Roosevelt Road, Hines, IL 60141, USA
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Bien MY, Hseu SS, Yien HW, Kuo BIT, Lin YT, Wang JH, Kou YR. Breathing pattern variability: a weaning predictor in postoperative patients recovering from systemic inflammatory response syndrome. Intensive Care Med 2004; 30:241-247. [PMID: 14647889 DOI: 10.1007/s00134-003-2073-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Accepted: 10/20/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To investigate whether breathing pattern variability can serve as a potential weaning predictor for postoperative patients recovering from systemic inflammatory response syndrome (SIRS). DESIGN AND SETTING A prospective measurement of retrospectively analyzed breathing pattern variability in a surgical intensive care unit. PATIENTS Seventy-eight mechanically ventilated SIRS patients who had undergone abdominal surgery were included when they were ready for weaning. They were divided into success (n=57) and failure (n=21) groups based upon their weaning outcome. MEASUREMENTS AND RESULTS Before weaning, tidal volume, total breath duration, inspiratory time, expiratory time, and peak inspiratory flow were continuously monitored for 30 min, while patients received 5 cmH2O pressure support weaning trial. After the patients successfully completed the trial, they were extubated. Successful weaning was defined as patients free from the ventilator for over 48 h, whereas a weaning failure was considered as reinstitution of mechanical ventilation within 48 h of extubation. The coefficient of variation and two values of standard deviation (SD1 and SD2; indicators of the dispersion of data points in the plot) obtained from the Poincaré plot of five respiratory parameters in the failure group were significantly lower than those in the success group. The area under the receiver operating characteristic curve of these variability indices was within the range of 0.73-0.80, indicating the accuracy of prediction. CONCLUSIONS Small breathing pattern variability is associated with a high incidence of weaning failure in postoperative patients recovering from SIRS, and this variability may potentially serve as a weaning predictor.
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Affiliation(s)
- Mauo-Ying Bien
- Institute of Physiology, School of Medicine, National Yang-Ming University, 11221, Taipei, Taiwan, Republic of China
- Department of Respiratory Therapy, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Shu-Shya Hseu
- Department of Anesthesiology, Department of Surgical Critical Care Unit, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Huey-Wen Yien
- Department of Anesthesiology, Department of Surgical Critical Care Unit, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Benjamin Ing-Tiau Kuo
- Laboratory of Epidemiology and Biostatistics, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Yu-Ting Lin
- Department of Anesthesiology, Department of Surgical Critical Care Unit, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Jia-Horng Wang
- Department of Respiratory Therapy, Taipei Veterans General Hospital, 11217, Taipei, Taiwan, Republic of China
| | - Yu Ru Kou
- Institute of Physiology, School of Medicine, National Yang-Ming University, 11221, Taipei, Taiwan, Republic of China.
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Caminal P, Domingo L, Giraldo BF, Vallverdú M, Benito S, Vázquez G, Kaplan D. Variability analysis of the respiratory volume based on non-linear prediction methods. Med Biol Eng Comput 2004; 42:86-91. [PMID: 14977227 DOI: 10.1007/bf02351015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This work proposed and studied a method of automatically classifying respiratory volume signals as high or low variability by means of non-linear analysis of the respiratory volume. The analysis used volume signals generated by the respiratory system to construct a model of its dynamics and to estimate the quality of the predictions made with the model. Different methods of prediction evaluation, prediction horizons and embedding dimensions were also analysed. Assessment of the method was made using a database that contained 40 respiratory volume signals classified using clinical criteria into two classes: low or high variability. The results obtained using the method of surrogate data provided evidence of non-linear determinism in the respiratory volume signals. A discriminant analysis carried out using non-linear prediction variables classified the respiratory volume signals with an accuracy of 95%.
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Affiliation(s)
- P Caminal
- Biomedical Engineering Research Centre, Departament ESAII, Technical University of Catalonia, Spain.
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Brack T, Jubran A, Tobin MJ. Dyspnea and decreased variability of breathing in patients with restrictive lung disease. Am J Respir Crit Care Med 2002; 165:1260-4. [PMID: 11991875 DOI: 10.1164/rccm.2201018] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Patients with restrictive lung disease are typically dyspneic and have an increase in overall respiratory center drive, as a result of increased lung elasticity. When we subjected healthy volunteers to external elastic loads, their variability of breathing was lessened. Accordingly, we hypothesized that patients with restrictive lung disease display decreased variability of breathing and, also, that decreased variability of breathing is related to dyspnea. Breathing pattern was measured nonobtrusively over 1 hour in 10 patients with restrictive lung disease and in 7 healthy subjects. On a separate occasion, dyspnea was measured while all subjects copied different tidal volumes and frequencies. Compared with healthy subjects, the random fraction of breath variability was reduced in patients with restrictive lung disease: 27 times for expiratory time, 12 times for tidal volume, and 6 times for inspiratory time (p < 0.01 in each instance). Conversely, the nonrandom, correlated fraction for tidal volume was increased almost 3-fold in the patients (p < 0.01). Small variations from average resting tidal volume caused marked increases in dyspnea in patients, and the relationship was parabolic (r2 = 0.97; p < 0.001). In conclusion, patients with restrictive lung disease adopt a tightly constrained breathing pattern, probably as a strategy for avoiding dyspnea.
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Affiliation(s)
- Thomas Brack
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr., Veterans Affairs Hospital, Hines, Illinois 60141, USA
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Van den Aardweg JG, Karemaker JM. Influence of chemoreflexes on respiratory variability in healthy subjects. Am J Respir Crit Care Med 2002; 165:1041-7. [PMID: 11956042 DOI: 10.1164/ajrccm.165.8.2104100] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The background of this study was the hypothesis that respiratory variability is influenced by chemoreflex regulation. In search for periodicities in the variability due to instability of the respiratory control system, spectral analysis was applied to breath-to-breath variables in 19 healthy subjects at rest. During room-air breathing, coherent oscillations in end-tidal CO2 (PET(CO2)) and mean inspiratory flow (VI/TI) were found in 15 subjects with frequencies mostly below 0.15 cycles per breath. Coherent oscillations in PET(CO2) and VI/TI were expressed by gain (0.13 to 0.34 L/second small middle dot kPa) and phase (-170 degrees to +8 degrees ). The oscillations in VI/TI were in phase with inspiratory volume (VI). A model that describes the effects of chemoreflex feedback to noise in the system could explain these gains and phases, whereas a model without chemoreflex could not. During 100% O2 breathing, only eight subjects had coherent oscillations in PET(CO2) and VI/TI. The coherent oscillations in PET(CO2) and VI/TI were interpreted as a manifestation of chemoreflex activity. We conclude that respiratory variability is not a random process but contains information on chemoreflex properties, such as the chemoreflex gain. The analysis of respiratory variability therefore provides a new tool to study the action of the chemoreflexes without application of external stimuli.
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Bruce EN. Assessing respiratory control during spontaneous breathing: practice may be more difficult than theory. Am J Respir Crit Care Med 2002; 165:1033-4. [PMID: 11956038 DOI: 10.1164/ajrccm.165.8.2202071a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Preas HL, Jubran A, Vandivier RW, Reda D, Godin PJ, Banks SM, Tobin MJ, Suffredini AF. Effect of endotoxin on ventilation and breath variability: role of cyclooxygenase pathway. Am J Respir Crit Care Med 2001; 164:620-6. [PMID: 11520726 DOI: 10.1164/ajrccm.164.4.2003031] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To evaluate the effects of endotoxemia on respiratory controller function, 12 subjects were randomized to receive endotoxin or saline; six also received ibuprofen, a cyclooxygenase inhibitor, and six received placebo. Administration of endotoxin produced fever, increased respiratory frequency, decreased inspiratory time, and widened alveolar-arterial oxygen tension gradient (all p < or = 0.001); these responses were blocked by ibuprofen. Independent of ibuprofen, endotoxin produced dyspnea, and it increased fractional inspiratory time, minute ventilation, and mean inspiratory flow (all p < or = 0.025). Endotoxin altered the autocorrelative behavior of respiratory frequency by increasing its autocorrelation coefficient at a lag of one breath, the number of breath lags with significant serial correlations, and its correlated fraction (all p < 0.05); these responses were blocked by ibuprofen. Changes in correlated behavior of respiratory frequency were related to changes in arterial carbon dioxide tension (r = 0.86; p < 0.03). Endotoxin decreased the oscillatory fraction of inspiratory time in both the placebo (p < 0.05) and ibuprofen groups (p = 0.06). In conclusion, endotoxin produced increases in respiratory motor output and dyspnea independent of fever and symptoms, and it curtailed the freedom to vary respiratory timing-a response that appears to be mediated by the cyclooxygenase pathway.
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Affiliation(s)
- H L Preas
- Critical Care Medicine Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
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Jubran A, Tobin MJ. Effect of isocapnic hypoxia on variational activity of breathing. Am J Respir Crit Care Med 2000; 162:1202-9. [PMID: 11029318 DOI: 10.1164/ajrccm.162.4.9907003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In the presence of either hypocapnia or sleep, hypoxia has been shown to induce periodic breathing and increase the total variational activity of breath components. It is not known whether hypoxia induces alterations in breathing variability during wakefulness and in the absence of hypocapnia. To address this issue, we studied nonobtrusively 14 healthy awake subjects before and during the delivery of a hypoxic gas mixture via a plastic hood; the subjects' oxygen saturation decreased from 98 to 79% and end-tidal carbon dioxide tension was kept constant. Compared with air, isocapnic hypoxia increased the gross variability of minute ventilation (V I), tidal volume (VT), inspiratory time (TI), and expiratory time (TE) (all p < 0.004). Isocapnic hypoxia decreased the autocorrelation coefficient at a lag of one breath for TE (p < 0. 008) and V I (p = 0.07), the number of consecutive breath lags having significant autocorrelation coefficients for TE (p = 0.03), and the cycle time of oscillations in V I (p = 0.03). When partitioned, the increase in total variational activity during isocapnic hypoxia was found to result from increases in the random fractions of V I, VT, TI, and TE (all p < 0.05), and the oscillatory fractions of V I, VT, and TE (all p < 0.03). In conclusion, hypoxia induced hidden oscillations in V I, VT, and TE despite wakefulness and an isocapnic state, suggesting that neural responses may have a more important role in the genesis of hypoxia-induced oscillations than previously reported.
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Affiliation(s)
- A Jubran
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr., Veterans Affairs Hospital and Loyola University of Chicago Stritch School of Medicine, Hines, Illinois, USA
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Bruce EN. Invited editorial on "Irregularities and power law distributions in the breathing pattern in preterm and term infants". J Appl Physiol (1985) 1998; 85:787-8. [PMID: 9729548 DOI: 10.1152/jappl.1998.85.3.787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Brack T, Jubran A, Tobin MJ. Effect of resistive loading on variational activity of breathing. Am J Respir Crit Care Med 1998; 157:1756-63. [PMID: 9620902 DOI: 10.1164/ajrccm.157.6.9704114] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To examine the effect of resistive loading on variational activity of breathing, we studied 18 healthy subjects breathing at rest and with inspiratory resistive loads of 3 and 6 cm H2O/L/s, applied randomly for 1 h each. Compared with resting breathing, a resistive load of 3 cm H2O/L/s decreased the total variational activity of expiratory time (TE) and minute ventilation (V I), whereas a load of 6 cm H2O/L/s increased the total variational activity of inspiratory time (TI). Compared with the load of 3 cm H2O/L/s, the load of 6 cm H2O/L/s increased total variational activity of tidal volume (VT), TI, TE, and V I. Partitioning of the total variational activity revealed that these alterations were due to changes in the random uncorrelated fraction. Compared with rest, both the resistive loads of 3 and 6 cm H2O/L/s increased the number of breath lags displaying significant serial correlations ("short-term memory") of TI. Compared with rest, the load of 3 cm H2O/L/s increased the autocorrelation coefficient at a lag of one breath for VT and the load of 6 cm H2O/L/s increased the correlated fraction of variational activity of VT. Thus, three measures of correlated behavior-autocorrelation coefficient at a lag of 1 breath, "short-term memory," and the correlated fraction of total variational activity- increased with loading. In conclusion, resistive loading changed total variational activity according to the size of the load: the random fraction decreased with the smaller load but increased with the larger load; in contrast, correlated behavior increased with both loads. The different behaviors of random and correlated variability with loading may reflect different physiologic influences on respiratory control.
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Affiliation(s)
- T Brack
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA
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