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Núñez Silveira JM, Gallardo A, García-Valdés P, Ríos F, Rodriguez PO, Felipe Damiani L. Reverse triggering during mechanical ventilation: Diagnosis and clinical implications. Med Intensiva 2023; 47:648-657. [PMID: 37867118 DOI: 10.1016/j.medine.2023.10.009] [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: 08/11/2023] [Revised: 09/04/2023] [Accepted: 09/04/2023] [Indexed: 10/24/2023]
Abstract
This review addresses the phenomenon of "reverse triggering", an asynchrony that occurs in deeply sedated patients or patients in transition from deep to light sedation. Reverse triggering has been reported to occur in 30-90% of all ventilated patients. The underlying pathophysiological mechanisms remain unclear, but "entrainment" is proposed as one of them. Detecting this asynchrony is crucial, and methods such as visual inspection, esophageal pressure, diaphragmatic ultrasound and automated methods have been used. Reverse triggering may have effects on lung and diaphragm function, probably mediated by the level of breathing effort and eccentric activation of the diaphragm. The optimal management of reverse triggering has not been established, but may include the adjustment of ventilatory parameters as well as of sedation level, and in extreme cases, neuromuscular block. It is important to understand the significance of this condition and its detection, but also to conduct dedicated research to improve its clinical management and potential effects in critically ill patients.
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Affiliation(s)
- Juan M Núñez Silveira
- Servicio de Kinesiología, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Adrián Gallardo
- Servicio de Kinesiología, Sanatorio Clínica Modelo de Morón, Morón, Buenos Aires, Argentina
| | - Patricio García-Valdés
- Departamento de Ciencias de la Salud, Carrera de Kinesiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; CardioREspirAtory Research Laboratory (CREAR), Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernando Ríos
- Casa Hospital San Juan De Dios, Ramos Mejía, Buenos Aires, Argentina
| | - Pablo O Rodriguez
- Unidad de Terapia Intensiva, Centro de Educación Médica e Investigaciones Clínicas (CEMIC), Buenos Aires, Argentina; Instituto Universitario CEMIC (IUC), Buenos Aires, Argentina
| | - L Felipe Damiani
- Departamento de Ciencias de la Salud, Carrera de Kinesiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; CardioREspirAtory Research Laboratory (CREAR), Pontificia Universidad Católica de Chile, Santiago, Chile.
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Takahashi K, Imai K. Effects of Acupuncture Stimulation to Cervical Sympathetic Trunk on Maximal Respiratory Mouth Pressure: A Randomized Crossover Study. Med Acupunct 2022; 34:184-192. [DOI: 10.1089/acu.2021.0040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Kazufumi Takahashi
- Department of Acupuncture and Moxibustion, Faculty of Health Care, and Research Institute of Oriental Medicine, Teikyo Heisei University, Tokyo, Japan
| | - Kenji Imai
- Department of Acupuncture and Moxibustion, Faculty of Health Care, and Research Institute of Oriental Medicine, Teikyo Heisei University, Tokyo, Japan
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Damiani LF, Engelberts D, Bastia L, Osada K, Katira BH, Otulakowski G, Goligher EC, Reid WD, Dubo S, Bruhn A, Post M, Kavanagh BP, Brochard LJ. Impact of Reverse Triggering Dyssynchrony During Lung-Protective Ventilation on Diaphragm Function: An Experimental Model. Am J Respir Crit Care Med 2021; 205:663-673. [PMID: 34941477 DOI: 10.1164/rccm.202105-1089oc] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Reverse triggering is a patient-ventilator interaction where a respiratory muscle contraction is triggered by a passive mechanical insufflation. Its impact on diaphragm structure and function is unknown. OBJECTIVE To establish an animal model of reverse triggering with lung injury receiving lung-protective ventilation and to assess its impact on structure and function of the diaphragm. METHODS Lung injury was induced by surfactant depletion and high stress ventilation in 32 ventilated pigs. Animals were allocated to receive passive mechanical ventilation or a lung-protective strategy with adjustments facilitating the occurrence of reverse triggering for 3 hours. Diaphragm function (transdiaphragmatic pressure (Pdi) during phrenic nerve stimulation [Force/frequency curve]) and structure (biopsies) were assessed. The impact of reverse triggering on diaphragm function was analyzed according to the breathing effort. RESULTS Compared to passive ventilation, the protective ventilation group with reverse triggering received significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm). An entrainment pattern of 1:1 was frequent. Breathing effort induced by reverse triggering was highly variable across animals. Reverse triggering with the lowest tercile of breathing effort was associated with 23% higher twitch Pdi compared to passive ventilation, whereas reverse triggering with high breathing effort was associated with a 10% lower twitch Pdi and a higher proportion of abnormal muscle fibers. CONCLUSION In a reproducible animal model of reverse triggering with variable levels of breathing effort and entrainment patterns, reverse triggering with high effort is associated with impaired diaphragm function whereas reverse triggering with low effort is associated with preserved diaphragm force.
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Affiliation(s)
- L Felipe Damiani
- Pontificia Universidad Católica de Chile - Facultad de Medicina, Departamento de Ciencias de la Salud, Santiago, Chile
| | - Doreen Engelberts
- Hospital for Sick Children, 7979, Physiology & Experimental Medicine, Toronto, Ontario, Canada
| | - Luca Bastia
- SickKids, 7979, Translational Medicine, Toronto, Ontario, Canada.,University of Milan-Bicocca, 9305, Medicine, Milano, Lombardia, Italy
| | - Kohei Osada
- SickKids, 7979, Translational Medicine, Toronto, Ontario, Canada
| | - Bhushan H Katira
- Hospital for Sick Children, 7979, Paediatric Critical Care Medicine, Toronto, Ontario, Canada
| | - Gail Otulakowski
- Hospital for Sick Children Research Institute, Lung Biology, Toronto, Ontario, Canada
| | - Ewan C Goligher
- University Health Network, 7989, Department of Medicine, Division of Respirology, Critical Care Program, Toronto, Ontario, Canada.,University of Toronto, 7938, Interdepartmental Division of Critical Care Medicine, Toronto, Ontario, Canada
| | - W Darlene Reid
- University of Toronto, Department of Physical Therapy, Toronto, Ontario, Canada
| | - Sebastián Dubo
- Universidad de Concepcion, 28056, Departamento de Kinesiología, Facultad de Medicina, Concepcion, Chile
| | - Alejandro Bruhn
- Pontificia Universidad Católica de Chile - Facultad de Medicina, Departamento de Medicina Intensiva, Santiago, Chile
| | - Martin Post
- Hospital for Sick Children, Lung Biology, Toronto, Ontario, Canada
| | - Brian P Kavanagh
- Hospital Sick Children, Department of Critical Care Medicine, Toronto, Ontario, Canada
| | - Laurent J Brochard
- St Michael's Hospital in Toronto, Li Ka Shing Knowledge Institute, Keenan Research Centre, Toronto, Ontario, Canada.,University of Toronto, 7938, Interdepartmental Division of Critical Care Medicine, Toronto, Ontario, Canada;
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Lin Z, Zhou J, Lin X, Wang Y, Zheng H, Huang W, Liu X, Li Y, Zhong N, Huang Y, Xu Y, Sang L. Reverse Trigger in Ventilated Non-ARDS Patients: A Phenomenon Can Not Be Ignored! Front Physiol 2021; 12:670172. [PMID: 34393811 PMCID: PMC8359823 DOI: 10.3389/fphys.2021.670172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 06/28/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction The role of reverse trigger (RT) was unknown in ventilated non-acute respiratory distress syndrome (ARDS) patients. So we conducted a retrospective study to evaluate the incidence, characteristics and physiologic consequence of RT in such population. Method Six ventilated non-ARDS patients were included, the esophageal balloon catheter were placed for measurements of respiratory mechanics in all patients. And the data were analyzed to identified the occurrence of RT, duration of the entrainment, the entrainment pattern or ratio, the phase difference (dP) and the phase angle (θ), phenotypes, Effects and clinical correlations of RT. Result RT was detected in four patients of our series (66.7%), and the occurrence of RT varying from 19 to 88.6% of their recording time in these 4 patients. One patient (No.2) showed a stable 1:1 ratio and Mid-cycle RT was the most common phenotype. However, the remained patients showed a mixed ratios, and Late RT was the most common phenotype, followed by RT with breath stacking. The average values of mean phase delay and phase angles were 0.39s (0.32, 0.98) and 60.52° (49.66, 102.24). Mean phase delay and phase angles were shorter in early reverse triggering with early and delayed relaxation, and longer in mid, late RT and RT with breath stacking. Pmus was variable between patients and phenotypes, and larger Pmus was generated in Early RT, Delayed Relaxation and mid cycle RT. When the RT occurred, the Peso increased 17.27 (4.91, 19.71) cmH2O compared to the controlled breathing, and the average value of incremental ΔPeso varied widely inter and intra patients (Table 3B and Figure 1). Larger ΔPeso was always generated in Early RT, Delayed Relaxation and mid cycle RT, accompanied by an significant increase of PL with 19.12 (0.75) cmH2O and 16.10 (6.23) cmH2O. Conclusion RT could also be observed in ventilated non-ARDS patients. The characteristics of pattern and phenotype was similar to RT in ARDS patients to a large extent. And RT appeared to alter lung stress and delivered volumes.
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Affiliation(s)
- Zhimin Lin
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Jing Zhou
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Xiaoling Lin
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Yingzhi Wang
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Haichong Zheng
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Weixiang Huang
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Xiaoqing Liu
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Yimin Li
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Nanshan Zhong
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Yongbo Huang
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Yuanda Xu
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China
| | - Ling Sang
- Department of Critical Care Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Respiratory Health, Guangzhou, China.,State Key Laboratory of Respiratory Disease, Guangzhou, China.,Guangzhou Laboratory, Guangzhou, China
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Murias G, de Haro C, Blanch L. Does this ventilated patient have asynchronies? Recognizing reverse triggering and entrainment at the bedside. Intensive Care Med 2015; 42:1058-61. [PMID: 26676866 DOI: 10.1007/s00134-015-4177-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 11/30/2015] [Indexed: 05/28/2023]
Affiliation(s)
- Gastón Murias
- Clínica Bazterrica y Clínica Santa Isabel, Buenos Aires, Argentina
| | - Candelaria de Haro
- Critical Care Center, Hospital de Sabadell, Corporació Sanitaria Universitària Parc Taulí, Parc Taulí, 1, 08208, Sabadell, Spain.,Institut de Investigació i Innovació Parc Taulí, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Lluis Blanch
- Critical Care Center, Hospital de Sabadell, Corporació Sanitaria Universitària Parc Taulí, Parc Taulí, 1, 08208, Sabadell, Spain. .,Institut de Investigació i Innovació Parc Taulí, Universitat Autònoma de Barcelona, Sabadell, Spain. .,CIBER Enfermedades Respiratorias, ISCIII, Madrid, Spain. .,Fundació Parc Taulí, Corporació Sanitaria Universitària Parc Taulí, Sabadell, Spain.
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Akoumianaki E, Lyazidi A, Rey N, Matamis D, Perez-Martinez N, Giraud R, Mancebo J, Brochard L, Richard JCM. Mechanical Ventilation-Induced Reverse-Triggered Breaths. Chest 2013. [DOI: 10.1378/chest.12-1817] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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MacDonald SM, Song G, Poon CS. Nonassociative learning promotes respiratory entrainment to mechanical ventilation. PLoS One 2007; 2:e865. [PMID: 17848996 PMCID: PMC1959120 DOI: 10.1371/journal.pone.0000865] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Accepted: 08/09/2007] [Indexed: 12/03/2022] Open
Abstract
Background Patient-ventilator synchrony is a major concern in critical care and is influenced by phasic lung-volume feedback control of the respiratory rhythm. Routine clinical application of positive end-expiratory pressure (PEEP) introduces a tonic input which, if unopposed, might disrupt respiratory-ventilator entrainment through sustained activation of the vagally-mediated Hering-Breuer reflex. We suggest that this potential adverse effect may be averted by two differentiator forms of nonassociative learning (habituation and desensitization) of the Hering-Breuer reflex via pontomedullary pathways. Methodology/Principal Findings We tested these hypotheses in 17 urethane-anesthetized adult Sprague-Dawley rats under controlled mechanical ventilation. Without PEEP, phrenic discharge was entrained 1∶1 to the ventilator rhythm. Application of PEEP momentarily dampened the entrainment to higher ratios but this effect was gradually adapted by nonassociative learning. Bilateral electrolytic lesions of the pneumotaxic center weakened the adaptation to PEEP, whereas sustained stimulation of the pneumotaxic center weakened the entrainment independent of PEEP. In all cases, entrainment was abolished after vagotomy. Conclusions/Significance Our results demonstrate an important functional role for pneumotaxic desensitization and extra-pontine habituation of the Hering-Breuer reflex elicited by lung inflation: acting as buffers or high-pass filters against tonic vagal volume input, these differentiator forms of nonassociative learning help to restore respiratory-ventilator entrainment in the face of PEEP. Such central sites-specific habituation and desensitization of the Hering-Breuer reflex provide a useful experimental model of nonassociative learning in mammals that is of particular significance in understanding respiratory rhythmogenesis and coupled-oscillator entrainment mechanisms, and in the clinical management of mechanical ventilation in respiratory failure.
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Affiliation(s)
- Shawna M. MacDonald
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Gang Song
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Chi-Sang Poon
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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8
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Zhou SY, Gebber GL, Zhong S, Barman SM. Pathways involved in synchronization of sympathetic nerve discharge to lung inflation. Brain Res 2002; 931:107-16. [PMID: 11897096 DOI: 10.1016/s0006-8993(02)02255-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In urethane-anesthetized cats, we tested the hypothesis that sympathetic nerve discharge (SND) is synchronized to lung inflation, in part, over a vagal afferent pathway that bypasses the central respiratory oscillator. For this purpose, partial coherence analysis was used to mathematically remove the portion of the relationship between intratracheal pressure (ITP; index of lung inflation) and inferior cardiac SND that was common to that between ITP and phrenic nerve activity (PNA; index of central respiratory cycle). ITP-SND partial coherence (PNA-related component removed) at the frequency of breathing should be significantly different from zero if a bypass pathway exists. This was found to be the case in paralyzed, artificially ventilated cats when lung inflation and rhythmic PNA were coupled in various ratios (e.g. 1:1, 3:1) and in spontaneously breathing cats. As expected, surgical vagotomy eliminated ITP-SND coherence in artificially ventilated cats. These findings support the view that a portion of the relationship between ITP and SND is independent of the influences of pulmonary stretch receptors on central respiratory networks.
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Affiliation(s)
- Shi-Yi Zhou
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824-1317, USA
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Simon PM, Habel AM, Daubenspeck JA, Leiter JC. Vagal feedback in the entrainment of respiration to mechanical ventilation in sleeping humans. J Appl Physiol (1985) 2000; 89:760-9. [PMID: 10926663 DOI: 10.1152/jappl.2000.89.2.760] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied the capacity of four "normal" and six lung transplant subjects to entrain neural respiratory activity to mechanical ventilation. Two transplant subjects were studied during wakefulness and demonstrated entrainment indistinguishable from that of normal awake subjects. We studied four normal subjects and four lung transplant subjects during non-rapid eye movement (NREM) sleep. Normal subjects entrained to mechanical ventilation over a range of ventilator frequencies that were within +/-3-5 breaths of the spontaneous respiratory rate of each subject. After lung transplantation, during which the vagi were cut, subjects did demonstrate entrainment during NREM sleep; however, entrainment only occurred at ventilator frequencies at or above each subject's spontaneous respiratory rate, and entrainment was less effective. We conclude that there is no absolute requirement for vagal feedback to induce entrainment in subjects, which is in striking contrast to anesthetized animals in which vagotomy uniformly abolishes entrainment. On the other hand, vagal feedback clearly enhances the fidelity of entrainment and extends the range of mechanical frequencies over which entrainment can occur.
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Affiliation(s)
- P M Simon
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Mayo Foundation, Rochester, MN 59055, USA
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Simon PM, Zurob AS, Wies WM, Leiter JC, Hubmayr RD. Entrainment of respiration in humans by periodic lung inflations. Effect of state and CO(2). Am J Respir Crit Care Med 1999; 160:950-60. [PMID: 10471624 DOI: 10.1164/ajrccm.160.3.9712057] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Lack of synchrony between a patient and the mechanical ventilator occurs when the respiratory rhythm of the patient fails to entrain to machine inflations. Entrainment implies a resetting of the respiratory rhythm such that a fixed temporal relationship exists between the onset of inspiratory activity and the onset of a mechanical breath. We examined the entrainment response to mechanical ventilation of normal humans over a range of machine rates during wakefulness and during isocapnic and hypercapnic NREM sleep. Wakefulness facilitated 1:1 entrainment of the respiratory rhythm to the mechanical ventilator over a wider range of machine frequencies than during NREM sleep (p < 0.001); isocapnic and hypercapnic conditions did not differ (p = 0.95). To evaluate the Hering-Breuer reflexes in the resetting of the respiratory rhythm during sleep, we examined changes in neural inspiratory time (TI) as the relationship between inspiratory efforts and onset of machine inflations changed. As inspiratory efforts extended into the machine inflation cycle, neural TI shortened. We conclude that entrainment responses of normal humans to mechanical ventilation differ depending on state, but mild increases in respiratory drive caused by CO(2) stimulation do not affect these entrainment responses. Furthermore, the changes in neural TI are consistent with observations in animal studies in which Hering-Breuer reflexes mediated entrainment.
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Affiliation(s)
- P M Simon
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Foundation, Rochester, Minnesota, USA
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Abstract
The dorsal column nuclei include the gracile and cuneate nuclei, which receive somatosensory information from the periphery and project to the ventroposterior nucleus of the contralateral thalamus. The aim of this study was to determine the electrophysiological and morphological characteristics of the neurons of the dorsal column nuclei and to identify synaptic events evoked by electrical stimulation of the dorsal column, using an in vitro slice preparation. The results show two types of neurons, termed type I and II. A repolarizing sag distinguished type I cells during hyperpolarizing current injection, suggesting the activation of a Q-current. Moreover, type I cells, but not type II cells, were capable of maintaining spontaneous rhythmic activity at 9-15 Hz. Both types of cells displayed a delay in their return to the resting membrane potential following hyperpolarizing current pulses, indicating the existence of an A-current. Electrical stimuli applied to the dorsal column elicited brief EPSPs and IPSPs in both cell types. EPSPs were abolished by 6-cyano-7-nitroquinoxaline-2,3-dione, indicating that they were mediated through non-NMDA receptors. IPSPs were blocked by picrotoxin, implying the activation of GABAA receptors. Intracellular staining with carboxyfluoresceine revealed that type I neurons had elongated somas and primary dendrites that extended radially. Type II cells were smaller and had round somas with few primary dendrites, most of them emerging from one pole of the soma. The axon of many type I neurons was stained and could be followed running ventrally and in rostral direction.
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Affiliation(s)
- A Nuñez
- Departamento de Mofrfologia, Facultad de Medicina, Universidad Autonoma de Madrid, Spain.
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Segundo JP, Vibert JF, Stiber M. Periodically-modulated inhibition of living pacemaker neurons--III. The heterogeneity of the postsynaptic spike trains, and how control parameters affect it. Neuroscience 1998; 87:15-47. [PMID: 9722139 DOI: 10.1016/s0306-4522(98)00101-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Codings involving spike trains at synapses with inhibitory postsynaptic potentials on pacemakers were examined in crayfish stretch receptor organs by modulating presynaptic instantaneous rates periodically (triangles or sines; frequencies, slopes and depths under, respectively, 5.0 Hz, 40.0/s/s and 25.0/s). Timings were described by interspike and cross-intervals ("phases"); patterns (dispersions, sequences) and forms (timing classes) were identified using pooled graphs (instant along the cycle when a spike occurs vs preceding interval) and return maps (plots of successive intervals). A remarkable heterogeneity of postsynaptic intervals and phases characterizes each modulation. All cycles separate into the same portions: each contains a particular form and switches abruptly to the next. Forms differ in irregularity and predictability: they are (see text) "p:q alternations", "intermittent", "phase walk-throughs", "messy erratic" and "messy stammering". Postsynaptic cycles are asymmetric (hysteresis). This contrasts with the presynaptic homogeneity, smoothness and symmetry. All control parameters are, individually and jointly, strongly influential. Presynaptic slopes, say, act through a postsynaptic sensitivity to their magnitude and sign; when increasing, hysteresis augments and forms change or disappear. Appropriate noise attenuates between-train contrasts, providing modulations are under 0.5 Hz. Postsynaptic natural intervals impose critical time bases, separating presynaptic intervals (around, above or below them) with dissimilar consequences. Coding rules are numerous and have restricted domains; generalizations are misleading. Modulation-driven forms are trendy pacemaker-driven forms. However, dissimilarities, slight when patterns are almost pacemaker, increase as inhibition departs from pacemaker and incorporate unpredictable features. Physiological significance-(1) Pacemaker-driven forms, simple and ubiquitous, appear to be elementary building blocks of synaptic codings, present always but in each case distorted typically. (2) Synapses are prototype: similar behaviours should be widespread, and networks simulations benefit by nonlinear units generating all forms. (3) Relevant to periodic functions are that few variables need be involved in form selection, that distortions are susceptible to noise levels and, if periods are heterogeneous, that simple input cycles impose heterogeneous outputs. (4) Slow Na inactivations are necessary for obtaining complex forms and hysteresis. Formal significance--(1) Pacemaker-driven forms and presumably their modulation-driven counterparts, pertain to universal periodic, intermittent, quasiperiodic and chaotic categories whose formal properties carry physiological connotations. (2) Only relatively elaborate, nonlinear geometric models show all forms; simpler ones, show only alternations and walk-throughs. (3) Bifurcations resemble those of simple maps that can provide useful guidelines. (4) Heterogeneity poses the unanswered question of whether or not the entire cycle and all portions have the same behaviours: therefore, whether trajectories are continuous or have discontinuities and/or singular points.
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Affiliation(s)
- J P Segundo
- Department of Neurobiology, Brain Research Institute, University of California, Los Angeles 90025-1763, USA
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13
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Segundo JP, Stiber M, Vibert JF, Hanneton S. Periodically modulated inhibition and its postsynaptic consequences--II. Influence of modulation slope, depth, range, noise and of postsynaptic natural discharges. Neuroscience 1995; 68:693-719. [PMID: 8577367 DOI: 10.1016/0306-4522(95)00170-n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This paper examines the relation, or "synaptic coding", between the discharges of inhibitory fibres whose instantaneous firing rate is modulated periodically and pacemaker postsynaptic neurons using crayfish synapses and point process statistics. Several control parameters were varied individually, and the other maintained constant as far as possible: it extends the preceding publication that described the general features and varied only the modulation frequency [Segundo et al. (1995) Neuroscience 68, 657-692]. Statistics were mainly cycle histograms and Lissajous diagrams (with presynaptic and post-synaptic histograms on the abscissae and ordinate, respectively), complemented occasionally by displays of intervals along time and of interval differences along order ("basic graphs" and "recurrence plots", respectively). The postsynaptic influence of modulated inhibitory discharges is characteristically sensitive to all control parameters examined. (1) The frequency was reported in the companion paper [Segundo et al. (1995) Neuroscience 68, 657-692]. (2) The average slope per half-cycle, controlled via either frequency or depth, acts by way of its magnitude and sign in ways revealed by hysteretic loops. Hysteresis increases and varies as the modulation's steepness increases: it is minor and with a single clockwise loop at small slopes, but major and multi-looped at the larger ones. Slopes, because of their different postsynaptic consequences, were separated into the categories of "steep", "gentle" and "abrupt" if around, respectively, 1.0, 30.0 and 150.0 s-2. The influence of slopes in restricted portions of the cycle depends on their position on the inhibitory rate scale. (3) The modulation's range acts by way of its depth and of its position on the inhibitory rate scale. Deeper ranges, when compared with the shallower ones they contain, induce effects similar to those of shallower modulations with their central portion, plus effects peculiar to them at extreme rates. Changes in range position from the centre to the extremes of the inhibitory rate scale are influential (e.g., saturations appear). Changes within the centre can be highly influential, particularly when ranges are narrow and close to the postsynaptic natural rate, and modulation frequencies are low: relations between corresponding rates can be linear increasing, linear decreasing or piecewise linear. Changes around extreme rates are negligible, however, and saturations are present. (4) The usual modulations whose individual cycles did not differ from the cycle histogram were compared to others with the same cycle histograms but whose individual cycles had an unpredictable fast variability referred to as "noise".(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J P Segundo
- Department of Anatomy and Cell Biology, University of California, Los Angeles 90024-1763, USA
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Segundo JP, Vibert JF, Stiber M, Hanneton S. Periodically modulated inhibition and its postsynaptic consequences--I. General features. Influence of modulation frequency. Neuroscience 1995; 68:657-92. [PMID: 8577366 DOI: 10.1016/0306-4522(95)00169-j] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Our aim was to examine the relation, or "synaptic coding", between spike trains across a synapse with inhibitory postsynaptic potentials when the presynaptic rate is modulated periodically and the postsynaptic cell is a pacemaker. Experiments were on the synapse in crayfish stretch receptor organs. Spike trains were considered point processes along time; the time series of corresponding pre- and postsynaptic intervals were extracted. Analyses used displays of intervals along time and order ("basic graphs", and "rasters", respectively), displays of differences between intervals along order ("recurrence plots"), cycle histograms (as such and as Lissajous diagrams with presynaptic and postsynaptic on the abscissae and ordinate, respectively), and correlation histograms. Cycle histograms and correlation histograms demonstrated that all presynaptic modulation frequencies (1/60-10 Hz) are reflected postsynaptically; novel frequencies may arise, not always relating simply to the pre- or postsynaptic ones. The transferred frequency domain is broad and physiologically meaningful. Indeed, vitally important functions have strong periodicities in all portions of the explored domain, and so do the discharges of participating neurons. Overall, pre- and postsynaptic discharges change oppositely, one accelerating while the other slows. Locally, however, pre- and postsynaptic discharges contrast clearly in other ways. The presynaptic evolution is everywhere smooth and orderly, half-cycles usually are symmetric, and there is a single kind of discharge, as expected because the presynaptic axon follows well the controlling stimuli. The postsynaptic cycle shows marked local distortions. These involve presynaptic domains called "congruent portions" where changes are in the same sense (e.g., joint accelerations), "saturated" domains where postsynaptic discharges are arrested, and asymmetric sensitivities to presynaptic change with hysteretic loops in the Lissajous diagrams; the postsynaptic discharge is heterogeneous showing dissimilar forms in succession. Congruent portions are either "positive segments" with pre- to postsynaptic rate ratios practically 1:1, 2:1, 1:1, or parts of Lissajous loops. Different modulation frequencies have different postsynaptic consequences. Differences involve the width and number of positive segments, the proportion of the cycle with saturation, the sense, magnitude and lead-lag characteristics of the hysteretic loops, etc. Because their consequences are separable, frequencies are classified within categories labelled "low" (under 0.5 Hz), "high" (between 0.5 and 5.0 Hz) and "very high" (over 5.0 Hz). Categories arise widely but each prevails in different biological functions (e.g., low or high in, respectively, respiration or vibratory sensitivity). The refactoriness of the inhibitory fibre affects how it can be modulated: consequently, the very high category resembles pacemaker discharges and was not analysed.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J P Segundo
- Department of Anatomy and Cell Biology, University of California, Los Angeles 90024-1763, USA
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Persegol L, Palisses R, Viala D. Different mechanisms involved in supraspinal and spinal reflex regulation of phrenic activity through chest movements. Neuroscience 1987; 23:631-40. [PMID: 3437984 DOI: 10.1016/0306-4522(87)90081-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The coordination of breathing activity with chest movements was compared in the same decorticate rabbit preparations prior to and after a transection at the C2 spinal level. Pharmacological activation was induced with a combination of nialamide and DOPA in the latter situation. The preparation was curarized and chest inflations and deflations were induced by a respirator whose parameters could be modified. In decorticate preparations, phrenic activity was coordinated 1:1 with the respirator period over a large range of imposed periods. Beyond the extreme values a new coupling was achieved with a ratio of either 1:2 or 2:1. Throughout the range of 1:1 coordination, phrenic bursting always happened at a preferred time in the respirator period, although this time differed for the various imposed periods. This coordinated activity required vagal inputs. After spinal transection the phrenic nerves were totally silent; DOPA administration allowed rhythmic activity to develop. In some preparations, phrenic bursts were coordinated 1:1 with the respirator period and remained so for all the imposed periods: the phase of these phrenic discharges relative to the respirator cycle was kept unchanged for the different periods. In addition, there was a modulation of amplitude superimposed on this 1:1 coupling. These spinal phrenic bursts were generally suppressed when the respirator was turned off. From these results, the coordination of phrenic activity with the respirator rate appears to be produced by different mechanisms in the decorticate and in the spinal preparations. In the decorticate animal the periodic vagal inflow reset the activity of the medullary inspiratory generator and entrains it at its own rate. The coordination observed in the spinal preparation results from a periodic peripheral activation of premotoneuronal or motoneural phrenic elements during inflation. If the central bursts provided by the spinal "respiration" generator can fire phrenic motoneurons above threshold, their timing is not dependent on the peripheral inflow; when the motoneurons are fired below threshold by these central inputs, they are probably summing together the central and peripheral excitations, which could account for the amplitude modulation of the coordinated phrenic bursts of pure reflex origin. Possible afferent pathways are discussed.
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Affiliation(s)
- L Persegol
- Laboratoire de Neurophysiologie, Faculté des Sciences Mirande, Dijon, France
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Bachoo M, Polosa C. Properties of the inspiration-related activity of sympathetic preganglionic neurones of the cervical trunk in the cat. J Physiol 1987; 385:545-64. [PMID: 3656168 PMCID: PMC1192360 DOI: 10.1113/jphysiol.1987.sp016507] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
1. The experiments reported here have examined some temporal characteristics of the inspiration-related sympathetic discharge of the cat in control conditions and during forcing of the respiratory oscillator into marked deviations from its natural frequency. The purpose of these experiments was to establish whether or not the relation of sympathetic to phrenic nerve activity shows properties consistent with the hypothesis that the inspiration-related sympathetic discharge is driven by a neural oscillator, independent of, but coupled and stably entrained to, the brain-stem respiratory oscillator. 2. The electrical activity of the whole cervical sympathetic trunk (n = 26) or of small strands of the cervical trunk containing single units (n = 20) and of the phrenic nerve was recorded in pentobarbitone-anaesthetized, paralysed, artificially ventilated, sino-aortic denervated cats. Most of the cats were bilaterally vagotomized. 3. The onset of the inspiratory burst of the sympathetic preganglionic neurones had a fixed delay from the onset of the phrenic nerve burst. The level of activity within the burst, in whole cervical trunk recording, reached a maximum in early inspiration and then was maintained at approximately this level for the rest of inspiration (twenty-two out of twenty-six cats). In four cats the activity level increased throughout the burst. Individual sympathetic preganglionic neurones displaying inspiration-related burst firing were characteristically recruited in early inspiration and thereafter maintained an approximately constant firing frequency for the rest of inspiration. 4. Electrical stimulation of afferents in the superior laryngeal nerve during various phases of the respiratory cycle caused equivalent, phase-dependent, resetting patterns of both phrenic nerve and inspiration-related sympathetic discharge. 5. In cats with intact vagus nerves, entrainment of the brain-stem respiratory oscillator to the frequency of the respiratory pump was used to change the frequency of the former, within limits, by changing the frequency of the latter. Over the range of frequencies tested, the pump-to-phrenic delay varied as a function of frequency, while the delay between phrenic and sympathetic burst onset was essentially independent of frequency. 6. In hyperthermic, hypocapnic cats phrenic nerve burst frequency increased up to about 300 bursts/min from a value of 15 bursts/min in normothermia-normocapnia. At all frequencies within this range the sympathetic burst maintained a delay, with respect to the phrenic burst, which was essentially independent of frequency.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M Bachoo
- Department of Physiology, McGill University, Montreal, Quebec, Canada
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17
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Abstract
The properties of sympathetic preganglionic neurone activity during expiration were studied in pentobarbitone-anaesthetized (n = 26) and in non-anaesthetized, mid-collicular decerebrate (n = 5), paralysed, artificially ventilated cats in which the electrical activity of the phrenic nerve and of the cervical sympathetic trunk was recorded. In control conditions (end-tidal PCO2 between 35 and 40 mmHg, zero end-expiratory pressure) sympathetic activity during expiration was either steady at a low level (n = 11) or showed a modest progressive increase from a low level in early expiration (n = 17). Very infrequently (n = 3), it showed a transient increase during the second half of expiration. Artificial ventilation with positive end-expiratory pressures in the range from 2.1 +/- 0.4 (mean +/- S.D.) to 6.7 +/- 0.6 cmH2O caused, in cats with intact vagus nerves, an increase in sympathetic neurone activity during the second half of expiration. Within this range of pressures, the magnitude of the increase was related to the magnitude of the positive end-expiratory pressure. This effect reversed at higher positive end-expiratory pressures. Pressures in excess of 10.2 +/- 1.8 cmH2O caused inhibition of sympathetic activity. The sympatho-excitatory effect of positive end-expiratory pressure disappeared after bilateral cervical vagotomy. With intact vagus nerves, it also disappeared at levels of systemic hypocapnia (end-tidal PCO2 less than or equal to 15 mmHg) which abolished phrenic nerve activity. In hypocapnia, artificial ventilation with peak tracheal pressures greater than 7.2 +/- 1.1 cmH2O caused inhibition of sympathetic activity, while ventilation with lower end-expiratory pressures had no effect on sympathetic activity. It may be concluded that the sympatho-excitatory effect of positive end-expiratory pressure is mediated by vagal afferents and requires a certain level of brain-stem respiratory neurone activity. Sympatho-excitation during expiration was also observed, in normocapnic conditions, during short-duration static lung inflation with tracheal pressures in the range from 2.5 +/- 0.3 to 7.0 +/- 0.8 cmH2O as well as during artificial ventilation with zero end-expiratory pressure when lung inflation occurred in expiration. These responses were abolished by bilateral cervical vagotomy and during systemic hypocapnia. Sympatho-excitation during expiration was also observed when systemic hypercapnia was produced in vagotomized cats by artificial ventilation with gas mixtures containing 5 or 10% CO2.(ABSTRACT TRUNCATED AT 400 WORDS)
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Abstract
The effects of periodic pulsatile stimulation on a simple mathematical model of biological oscillations, called the radial isochron clock (RIC), are investigated as a function of stimulus frequency and amplitude. This system can be reduced to a two parameter, one-dimensional circle map. Numerical and topological methods are used to give a very detailed picture of the observed bifurcations over the complete range of parameters. The bifurcations are generic for a class of models which generalize the RIC.
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