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Ribeiro LDJA, Bastos VHDV, Coertjens M. Breath-holding as model for the evaluation of EEG signal during respiratory distress. Eur J Appl Physiol 2024; 124:753-760. [PMID: 38105311 DOI: 10.1007/s00421-023-05379-x] [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: 08/08/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
PURPOSE Research describes the existence of a relationship between cortical activity and the regulation of bulbar respiratory centers through the evaluation of the electroencephalographic (EEG) signal during respiratory challenges. For example, we found evidences of a reduction in the frequency of the EEG (alpha band) in both divers and non-divers during apnea tests. For instance, this reduction was more prominent in divers due to the greater physiological disturbance resulting from longer apnea time. However, little is known about EEG adaptations during tests of maximal apnea, a test that voluntarily stops breathing and induces dyspnea. RESULTS Through this mini-review, we verified that a protocol of successive apneas triggers a significant increase in the maximum apnea time and we hypothesized that successive maximal apnea test could be a powerful model for the study of cortical activity during respiratory distress. CONCLUSION Dyspnea is a multifactorial symptom and we believe that performing a successive maximal apnea protocol is possible to understand some factors that determine the sensation of dyspnea through the EEG signal, especially in people not trained in apnea.
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Affiliation(s)
- Lucas de Jesus Alves Ribeiro
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil
- Brain Mapping and Functionality Laboratory, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
| | - Victor Hugo do Vale Bastos
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil
- Postgraduate Program in Biomedical Sciences, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
- Brain Mapping and Functionality Laboratory, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
| | - Marcelo Coertjens
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil.
- Postgraduate Program in Biomedical Sciences, Universidade Federal do Delta do Parnaíba, Piauí, Brazil.
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Feinstein JS, Gould D, Khalsa SS. Amygdala-driven apnea and the chemoreceptive origin of anxiety. Biol Psychol 2022; 170:108305. [PMID: 35271957 DOI: 10.1016/j.biopsycho.2022.108305] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 02/09/2022] [Accepted: 03/03/2022] [Indexed: 12/13/2022]
Abstract
Although the amygdala plays an important part in the pathogenesis of anxiety and generation of exteroceptive fear, recent discoveries have challenged the directionality of this brain-behavior relationship with respect to interoceptive fear. Here we highlight several paradoxical findings including: (1) amygdala lesion patients who experience excessive fear and panic following inhalation of carbon dioxide (CO2), (2) clinically anxious patients who have significantly smaller (rather than larger) amygdalae and a pronounced hypersensitivity toward CO2, and (3) epilepsy patients who exhibit apnea immediately following stimulation of their amygdala yet have no awareness that their breathing has stopped. The above findings elucidate an entirely novel role for the amygdala in the induction of apnea and inhibition of CO2-induced fear. Such a role is plausible given the strong inhibitory connections linking the central nucleus of the amygdala with respiratory and chemoreceptive centers in the brainstem. Based on this anatomical arrangement, we propose a model of Apnea-induced Anxiety (AiA) which predicts that recurring episodes of apnea are being unconsciously elicited by amygdala activation, resulting in transient spikes in CO2 that provoke fear and anxiety, and lead to characteristic patterns of escape and avoidance behavior in patients spanning the spectrum of anxiety. If this new conception of AiA proves to be true, and activation of the amygdala can repeatedly trigger states of apnea outside of one's awareness, then it remains possible that the chronicity of anxiety disorders is being interoceptively driven by a chemoreceptive system struggling to maintain homeostasis in the midst of these breathless states.
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Affiliation(s)
- Justin S Feinstein
- Laureate Institute for Brain Research, Tulsa, Oklahoma, USA, 74136; University of Tulsa, Oxley College of Health Sciences, Tulsa, Oklahoma, USA, 74104; University of Iowa, Department of Neurology, Iowa City, Iowa, USA, 52242.
| | - Dylan Gould
- Laureate Institute for Brain Research, Tulsa, Oklahoma, USA, 74136
| | - Sahib S Khalsa
- Laureate Institute for Brain Research, Tulsa, Oklahoma, USA, 74136; University of Tulsa, Oxley College of Health Sciences, Tulsa, Oklahoma, USA, 74104
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3
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Tural U, Iosifescu DV. A systematic review and network meta-analysis of carbon dioxide provocation in psychiatric disorders. J Psychiatr Res 2021; 143:508-515. [PMID: 33250190 DOI: 10.1016/j.jpsychires.2020.11.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/09/2020] [Accepted: 11/15/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND False suffocation alarm hypothesis has been widely used to explain carbon dioxide hypersensitivity in panic disorder (PD). However, hypersensitivity to carbon dioxide has been observed in other psychiatric disorders. We explored the specificity of carbon dioxide inhalation as a panic provocation test among psychiatric disorders via network meta-analysis. METHODS A systematic literature search on PubMed, EMBASE, and PsycNET was performed to acquire the studies using the carbon dioxide provocation test in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and checklists. Odds ratios (OR) for a panic attack (PA) induced by the carbon dioxide inhalation tests were extracted from each of the original studies and were pooled using the random-effects model. RESULTS Network meta-analysis on a pool of 2181 participants from 41 studies was used to compare the efficacy of carbon dioxide provocation tests among psychiatric disorders. The network meta-analysis showed that the odds for PA in response to carbon dioxide inhalation are higher in patients with PD, premenstrual dysphoric syndrome (PMDD), and social anxiety disorder (SAD) than healthy controls (HC). The odds for PA were not significantly different among patients with generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), major depressive disorder (MDD), and healthy controls (HC). CONCLUSIONS The vulnerability to the carbon dioxide provocation test is not limited to PD. The specificity of the test for PD is questionable, as individuals suffering from PMDD and SAD are also significantly more responsive to carbon dioxide inhalation compared to HC, OCD, MDD, and GAD. There may be shared underpinning biological mechanisms between PD, PMDD, and SAD.
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Affiliation(s)
- Umit Tural
- Clinical Research Division, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
| | - Dan V Iosifescu
- Clinical Research Division, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA; Psychiatry Department, New York University School of Medicine, New York, NY 10016, USA
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Tural U, Iosifescu DV. Comparison of Sodium Lactate Infusion and Carbon Dioxide Inhalation Panic Provocation Tests: A Meta-analysis. PHARMACOPSYCHIATRY 2021; 55:87-94. [PMID: 34666404 DOI: 10.1055/a-1589-6049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND Sodium lactate (NaL) infusion and carbon dioxide (CO2) inhalation are proven to provoke acute panic attacks (PAs) in patients with panic disorder (PD). A systematic literature search and meta-analysis were performed to compare the effect sizes of these methods. METHODS Odds ratios were calculated for each of the original studies and were pooled using the random-effects model. RESULTS Either NaL or CO2 provocations significantly increased the rates of PAs in individuals with PD compared to those in healthy controls. However, the effect size of NaL infusion (OR=25.13, 95% CI=15.48-40.80) was significantly greater than that of CO2 inhalation (OR=10.58, 95%CI=7.88-14.21). CONCLUSION The evidence for the efficacy of the two panic provocation tests is very strong. Yet, the results support the superiority of NaL infusion over CO2 inhalation challenge as a panic provocation test. Thus, lactate seems a much stronger stimulus than CO2 for the brain suffocation detector.
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Affiliation(s)
- Umit Tural
- Clinical Research Division, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, USA
| | - Dan V Iosifescu
- Clinical Research Division, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, USA.,Psychiatry Department, New York University School of Medicine, New York, USA
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5
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McKeown P, O’Connor-Reina C, Plaza G. Breathing Re-Education and Phenotypes of Sleep Apnea: A Review. J Clin Med 2021; 10:jcm10030471. [PMID: 33530621 PMCID: PMC7865730 DOI: 10.3390/jcm10030471] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/13/2022] Open
Abstract
Four phenotypes of obstructive sleep apnea hypopnea syndrome (OSAHS) have been identified. Only one of these is anatomical. As such, anatomically based treatments for OSAHS may not fully resolve the condition. Equally, compliance and uptake of gold-standard treatments is inadequate. This has led to interest in novel therapies that provide the basis for personalized treatment protocols. This review examines each of the four phenotypes of OSAHS and explores how these could be targeted using breathing re-education from three dimensions of functional breathing: biochemical, biomechanical and resonant frequency. Breathing re-education and myofunctional therapy may be helpful for patients across all four phenotypes of OSAHS. More research is urgently needed to investigate the therapeutic benefits of restoring nasal breathing and functional breathing patterns across all three dimensions in order to provide a treatment approach that is tailored to the individual patient.
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Affiliation(s)
- Patrick McKeown
- Buteyko Clinic International, Loughwell, Moycullen, Co., H91 H4C1 Galway, Ireland;
| | - Carlos O’Connor-Reina
- Otorhinolaryngology Department, Hospital Quironsalud Marbella, 29603 Marbella, Spain;
- Otorhinolaryngology Department, Hospital Quironsalud Campo de Gibraltar, 11379 Palmones, Spain
| | - Guillermo Plaza
- Otorhinolaryngology Department, Hospital Universitario de Fuenlabrada, Universidad Rey Juan Carlos, 28042 Madrid, Spain
- Otorhinolaryngology Department, Hospital Sanitas la Zarzuela, 28023 Madrid, Spain
- Correspondence:
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Kyriakoulis P, Kyrios M, Nardi AE, Freire RC, Schier M. The Implications of the Diving Response in Reducing Panic Symptoms. Front Psychiatry 2021; 12:784884. [PMID: 34912254 PMCID: PMC8667218 DOI: 10.3389/fpsyt.2021.784884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/04/2021] [Indexed: 11/26/2022] Open
Abstract
Increased CO2 sensitivity is common in panic disorder (PD) patients. Free divers who are known for their exceptional breathing control have lower CO2 sensitivity due to training effects. This study aimed to investigate the immediate effects of cold facial immersion (CFI), breath holding and CO2 challenges on panic symptoms. Healthy participants and patients with PD were subjected to four experimental conditions in a randomly assigned order. The four conditions were (a) breath-holding (BH), (b) CFI for 30 s, (c) CO2 challenge, and (d) CO2 challenge followed by CFI. Participants completed a battery of psychological measures, and physiological data (heart rate and respiration rate) were collected following each experimental condition. Participants with PD were unable to hold their breath for as long as normal controls; however, this finding was not significant, potentially due to a small sample size. Significant reductions in both physiological and cognitive symptoms of panic were noted in the clinical group following the CFI task. As hypothesized, the CFI task exerted demonstrable anxiolytic effects in the clinical group in this study by reducing heart rate significantly and lessening self-reported symptoms of anxiety and panic. This outcome demonstrates the promise of the CFI task for clinical applications.
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Affiliation(s)
- Peter Kyriakoulis
- School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Michael Kyrios
- College of Education, Psychology & Social Work, Orama Institute for Mental Health & Wellbeing, Flinders University, Adelaide, SA, Australia
| | - Antonio Egidio Nardi
- Institute of Psychiatry-Federal University of Rio De Janeiro, Rio De Janeiro, Brazil
| | - Rafael C Freire
- Institute of Psychiatry-Federal University of Rio De Janeiro, Rio De Janeiro, Brazil.,Department of Psychiatry and Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada
| | - Mark Schier
- School of Health, Swinburne University, Hawthorn, VIC, Australia
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McIntosh RC, Hoshi RA, Timpano KR. Take my breath away: Neural activation at breath-hold differentiates individuals with panic disorder from healthy controls. Respir Physiol Neurobiol 2020; 277:103427. [PMID: 32120012 DOI: 10.1016/j.resp.2020.103427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 02/12/2020] [Accepted: 02/24/2020] [Indexed: 01/04/2023]
Abstract
There is neuroanatomical evidence of an "extended fear network" of brain structures involved in the etiology of panic disorder (PD). Although ventilatory distrubance is a primary symptom of PD these sensations may also trigger onset of a panic attack (PA). Here, a voluntary breath-holding paradigm was used to mimic the hypercapnia state in order to compare blood oxygen level-dependent (BOLD) response, at the peak of a series of 18 s breath-holds, of 21 individuals with PD to 21 low anxiety matched controls. Compared to the rest condition, BOLD activity at the peak (12 - 18 s) of the breath-hold was greater for PD versus controls within a number of structures implicated in the extended fear network, including hippocampus, thalamus, and brainstem. Activation was also observed in cortical structures that are shown to be involved in interoceptive and self-referential processing, such as right insula, middle frontal gyrus, and precuneus/posterior cingulate. In lieu of amygdala activation, our findings show elevated activity throughout an extended network of cortical and subcortical structures involved in contextual, interoceptive and self-referential processing when individuals with PD engage in voluntary breath-holding.
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Affiliation(s)
- R C McIntosh
- Department of Psychology, University of Miami, 1120 NW 14th Street, Miami, FL, 33136, United States.
| | - R A Hoshi
- Clinical and Epidemiological Research Center, Sao Paulo University. 2565 Professor Lineu Prestes Ave, Sao Paulo, 05508-000, Brazil
| | - K R Timpano
- Department of Psychology, University of Miami, 1120 NW 14th Street, Miami, FL, 33136, United States
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8
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Haywood A, Duc J, Good P, Khan S, Rickett K, Vayne-Bossert P, Hardy JR. Systemic corticosteroids for the management of cancer-related breathlessness (dyspnoea) in adults. Cochrane Database Syst Rev 2019; 2:CD012704. [PMID: 30784058 PMCID: PMC6381295 DOI: 10.1002/14651858.cd012704.pub2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Dyspnoea is a common symptom in advanced cancer, with a prevalence of up to 70% among patients at end of life. The cause of dyspnoea is often multifactorial, and may cause considerable psychological distress and suffering. Dyspnoea is often undertreated and good symptom control is less frequently achieved in people with dyspnoea than in people with other symptoms of advanced cancer, such as pain and nausea. The exact mechanism of action of corticosteroids in managing dyspnoea is unclear, yet corticosteroids are commonly used in palliative care for a variety of non-specific indications, including pain, nausea, anorexia, fatigue and low mood, despite being associated with a wide range of adverse effects. In view of their widespread use, it is important to seek evidence of the effects of corticosteroids for the management of cancer-related dyspnoea. OBJECTIVES To assess the effects of systemic corticosteroids for the management of cancer-related breathlessness (dyspnoea) in adults. SEARCH METHODS We searched CENTRAL, MEDLINE, Embase, CINAHL, Science Citation Index Web of Science, Latin America and Caribbean Health Sciences (LILACS) and clinical trial registries, from inception to 25 January 2018. SELECTION CRITERIA We included randomised controlled trials that included adults aged 18 years and above. We included participants with cancer-related dyspnoea when randomised to systemic corticosteroids (at any dose) administered for the relief of cancer-related dyspnoea or any other indication, compared to placebo, standard or alternative treatment. DATA COLLECTION AND ANALYSIS Five review authors independently assessed trial quality and three extracted data. We used means and standard deviations for each outcome to report the mean difference (MD) with 95% confidence interval (CI). We assessed the risk of bias and quality of evidence using GRADE. We extracted primary outcomes of sensory-perceptual experience of dyspnoea (intensity of dyspnoea), affective distress (quality of dyspnoea) and symptom impact (burden of dyspnoea or impact on function) and secondary outcomes of serious adverse events, participant satisfaction with treatment and participant withdrawal from trial. MAIN RESULTS Two studies met the inclusion criteria, enrolling 157 participants (37 participants in one study and 120 in the other study), of whom 114 were included in the analyses. The studies compared oral dexamethasone to placebo, followed by an open-label phase in one study. One study lasted seven days, and the duration of the other study was 15 days.We were unable to conduct many of our predetermined analyses due to different agents, dosages, comparators and outcome measures, routes of drug delivery, measurement scales and time points. Subgroup analysis according to type of cancer was not possible.Primary outcomesWe included two studies (114 participants) with data at one week in the meta-analysis for change in dyspnoea intensity/dyspnoea relief from baseline. Corticosteroid therapy with dexamethasone resulted in an MD of lower dyspnoea intensity compared to placebo at one week (MD -0.85 lower dyspnoea (scale 0-10; lower score = less breathlessness), 95% CI -1.73 to 0.03; very low-quality evidence), although we were uncertain as to whether corticosteroids had an important effect on dyspnoea as results were imprecise. We downgraded the quality of evidence by three levels from high to very low due to very serious study limitations and imprecision.One study measured affective distress (quality of dyspnoea) and results were similar between groups (29 participants; very low-quality evidence). We downgraded the quality of the evidence three times for imprecision, inconsistency, and serious study limitations.Both studies assessed symptom impact (burden of dyspnoea or impact on function) (113 participants; very low-quality evidence). In one study, it was unclear whether dexamethasone had an effect on dyspnoea as results were imprecise. The second study showed more improvement for physical well-being scores at days eight and 15 in the dexamethasone group compared with the control group, but there was no evidence of a difference for FACIT social/family, emotional or functional scales. We downgraded the quality of the evidence three times for imprecision, inconsistency, and serious study limitations.Secondary outcomesDue to the lack of homogenous outcome measures and inconsistency in reporting, we could not perform quantitative analysis for any secondary outcomes. In both studies, the frequency of adverse events was similar between groups, and corticosteroids were generally well tolerated. The withdrawal rates for the two studies were 15% and 36%. Reasons for withdrawal included lost to follow-up, participant or carer (or both) refusal, and death due to disease progression. We downgraded the quality of evidence for these secondary outcomes by three levels from high to very low due to serious study limitations, inconsistency and imprecision.Neither study examined participant satisfaction with treatment. AUTHORS' CONCLUSIONS There are few studies assessing the effects of systemic corticosteroids on cancer-related dyspnoea in adults with cancer. We judged the evidence to be of very low quality that neither supported nor refuted corticosteroid use in this population. Further high-quality studies are needed to determine if corticosteroids are efficacious in this setting.
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Affiliation(s)
- Alison Haywood
- School of Pharmacy, Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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9
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Haywood A, Duc J, Good P, Khan S, Rickett K, Vayne-Bossert P, Hardy JR. Systemic corticosteroids for the management of cancer-related breathlessness (dyspnoea) in adults. Hippokratia 2017. [DOI: 10.1002/14651858.cd012704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alison Haywood
- School of Pharmacy, Menzies Health Institute Queensland, Griffith University; Gold Coast Australia
- Mater Research Institute - The University of Queensland; Brisbane Australia
| | - Jacqueline Duc
- Mater Health Services; Department of Palliative and Supportive Care; Brisbane Australia
- Faculty of Medicine; University of Brisbane Brisbane Australia
- Children's Health Queensland; Paediatric Palliative Care Service; Brisbane Australia
| | - Phillip Good
- Mater Research Institute - The University of Queensland; Brisbane Australia
- Mater Health Services; Department of Palliative and Supportive Care; Brisbane Australia
- St Vincent's Private Hospital; Department of Palliative Care; 411 Main Street Kangaroo Point Brisbane Queensland Australia 4169
| | - Sohil Khan
- School of Pharmacy, Menzies Health Institute Queensland, Griffith University; Gold Coast Australia
- Mater Research Institute - The University of Queensland; Brisbane Australia
| | - Kirsty Rickett
- UQ/Mater McAuley Library; The University of Queensland Library; Raymond Terrace Brisbane Queensland Australia 4101
| | - Petra Vayne-Bossert
- University Hospitals of Geneva; Department of Readaptation and Palliative Medicine; 11 chemin de la Savonnière Collonge-Bellerive Geneva Switzerland 1245
| | - Janet R Hardy
- Mater Research Institute - The University of Queensland; Brisbane Australia
- Mater Health Services; Department of Palliative and Supportive Care; Brisbane Australia
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Pirildar S, Bayraktar E, Berdeli A, Kucuk O, Alkin T, Kose T. Progesterone Receptor Gene Polymorphism in Panic Disorder: Associations with Agoraphobia and Respiratory Subtype of Panic Disorder. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/10177833.2010.11790650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Sebnem Pirildar
- Ege University School of Medicine Psychiatry Department, Bornova, Izmir-Turkey
| | - Erhan Bayraktar
- Ege University School of Medicine Psychiatry Department, Bornova, Izmir-Turkey
| | - Afig Berdeli
- Ege University School of Medicine Department of Pediatrics, Molecular Genetic Laboratory, Izmir-Turkey
| | | | - Tunc Alkin
- Dokuz Eylul University School of Medicine Psychiatry Department, Izmir-Turkey
| | - Timur Kose
- Ege University School of Medicine Biostatistics Department, Izmir-Turkey
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Amaral JMXD, Spadaro PTM, Pereira VM, Silva ACDOE, Nardi AE. The carbon dioxide challenge test in panic disorder: a systematic review of preclinical and clinical research. BRAZILIAN JOURNAL OF PSYCHIATRY 2013; 35:318-31. [DOI: 10.1590/1516-4446-2012-1045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 12/28/2012] [Indexed: 11/22/2022]
Affiliation(s)
- Julio Mario Xerfan do Amaral
- Universidade Federal do Rio de Janeiro, Brazil; UFRJ, Brazil; National Science and Technology Institute for Translational Medicine
| | - Pedro Tadeu Machado Spadaro
- Universidade Federal do Rio de Janeiro, Brazil; UFRJ, Brazil; National Science and Technology Institute for Translational Medicine
| | | | | | - Antonio Egidio Nardi
- UFRJ, Brazil; National Science and Technology Institute for Translational Medicine
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12
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Grassi M, Caldirola D, Vanni G, Guerriero G, Piccinni M, Valchera A, Perna G. Baseline respiratory parameters in panic disorder: a meta-analysis. J Affect Disord 2013; 146:158-73. [PMID: 23107756 DOI: 10.1016/j.jad.2012.08.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 08/21/2012] [Accepted: 08/21/2012] [Indexed: 02/01/2023]
Abstract
BACKGROUND The presence of abnormalities in baseline respiratory function of subjects with panic disorder (PD) is expected according to PD respiratory theories. We aimed to meta-analyze results from studies comparing baseline respiratory and hematic parameters related to respiration between subjects with PD and controls. METHODS A literature research in bibliographic databases was performed. Fixed-effects models were applied for all parameters while random-effects models only when suitable (at least 10 independent studies). Several moderator analyses and publication bias diagnostics were performed. RESULTS We found significantly higher mean minute ventilation and lower et-pCO(2) in subjects with PD than controls. Moreover we also found evidences of reduced HCO(3)(-) and PO(4)(-) hematic concentrations, higher indexes of respiratory variability/irregularity and higher rate of sighs and apneas. Evidence of heterogeneity was partly explained by moderator analyses. No relevant publication bias was found. LIMITATIONS Several shortcomings affected the included studies, such as over-inclusive recruitment criteria, samples unbalanced for socio-demographic characteristics, lack of statistical details and small number of studies available for several parameters. DISCUSSION Our results support the idea of abnormalities in respiratory function of subjects with PD. Compared to controls, they showed baseline hyperventilation; the results from hematic parameters suggest that hyperventilation may be chronic and not simply caused by their high anxiety levels during respiratory assessment. Evidences of higher variability and irregularity in respiratory patterns of subjects with PD were also found. It is unclear to what extent the higher rate of sighs and apneas may explain the other baseline respiratory abnormalities found in PD.
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Affiliation(s)
- Massimiliano Grassi
- Department of Clinical Neurosciences, Villa San Benedetto Hospital, Hermanas Hospitalarias, FoRiPsi, Albese con Cassano, Italy.
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Vickers K. Hypersensitivity to hypercapnia: definition/(s). Psychiatry Res 2012; 197:7-12. [PMID: 22401967 DOI: 10.1016/j.psychres.2011.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 08/29/2011] [Accepted: 11/08/2011] [Indexed: 10/28/2022]
Abstract
Empirical evidence indicates that panic disorder (PD) patients experience hypersensitivity to hypercapnia, a condition in which the blood level of carbon dioxide exceeds the normal value. The importance of this research line is substantial and indeed, hypercapnic hypersensitivity has been advanced as a possible endophenotype of panic. Definitions of "hypersensitivity," however, have varied. The purpose of this brief review is to delineate and critique different definitions of hypercapnic hypersensitivity. Several definitions - panic attack rate, panic symptoms including dyspnea, subjective anxiety, and respiratory disturbance - are explored. The review concludes that although no ideal definition has emerged, marked anxiety post-hypercapnia has substantial support as a putative trait marker of PD. The term "subjective hypersensitivity" (Coryell et al., 2001) is re-introduced to denote pronounced anxiety post-hypercapnia and recommended for use along with its previous definition: increased self-reported anxiety measured on a continuous visual analog scale, already widely in use. Due to the well-established link between panic and respiration, definitional candidates focusing on aberrant respiratory response - less investigated as trait markers of PD in high risk studies - warrant scrutiny as well. Several reasons why definitional clarity might be beneficial are presented, along with ideas for future research.
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Affiliation(s)
- Kristin Vickers
- Department of Psychology, Ryerson University, Toronto, ON, Canada.
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Wan L, Stans L, Bogaerts K, Decramer M, Van den Bergh O. Sensitization in Medically Unexplained Dyspnea. Chest 2012; 141:989-995. [DOI: 10.1378/chest.11-1423] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Parshall MB, Schwartzstein RM, Adams L, Banzett RB, Manning HL, Bourbeau J, Calverley PM, Gift AG, Harver A, Lareau SC, Mahler DA, Meek PM, O'Donnell DE. An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea. Am J Respir Crit Care Med 2012; 185:435-52. [PMID: 22336677 PMCID: PMC5448624 DOI: 10.1164/rccm.201111-2042st] [Citation(s) in RCA: 1109] [Impact Index Per Article: 92.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.
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Parshall MB, Schwartzstein RM, Adams L, Banzett RB, Manning HL, Bourbeau J, Calverley PM, Gift AG, Harver A, Lareau SC, Mahler DA, Meek PM, O'Donnell DE. An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea. Am J Respir Crit Care Med 2012. [PMID: 22336677 DOI: 10.1164/rccm.201111–2042st] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.
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Muhtz C, Yassouridis A, Daneshi J, Braun M, Kellner M. Acute panicogenic, anxiogenic and dissociative effects of carbon dioxide inhalation in patients with post-traumatic stress disorder (PTSD). J Psychiatr Res 2011; 45:989-93. [PMID: 21324483 DOI: 10.1016/j.jpsychires.2011.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Revised: 12/14/2010] [Accepted: 01/13/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Increased anxiety and panic to inhalation of carbon dioxide (CO(2)) has been described in patients with anxiety disorders, especially panic disorder, compared to healthy subjects. Post-traumatic stress disorder (PTSD) has been hypothesised to resemble panic disorder and is currently classified as an anxiety disorder in DSM-IV. However, there are only very few data available about the sensitivity of patients with PTSD to CO(2). METHODS In 10 patients with PTSD, 10 sex- and age-matched healthy subjects and 8 patients with panic disorder we assessed anxiety, panic, dissociative and PTSD symptoms before and after a single vital capacity inhalation of 35% CO(2). RESULTS Patients with PTSD showed an increased anxiety, panic and dissociative reaction to the inhalation of 35% CO(2) compared to healthy participants. PTSD subjects' responses were indistinguishable from those of panic patients. Additionally, PTSD-typical symptoms like post-traumatic flashbacks were provoked in patients with PTSD after the inhalation of CO(2). CONCLUSIONS In our sample, PTSD was associated with an increased CO(2) reactivity, pointing to an increased susceptibility of PTSD patients to CO(2) challenge.
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Affiliation(s)
- Christoph Muhtz
- Department of Psychiatry and Psychotherapy, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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Effects of Breathing Training on Voluntary Hypo- and Hyperventilation in Patients with Panic Disorder and Episodic Anxiety. Appl Psychophysiol Biofeedback 2011; 36:81-91. [DOI: 10.1007/s10484-011-9150-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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History of suffocation, state-trait anxiety, and anxiety sensitivity in predicting 35% carbon dioxide-induced panic. Psychiatry Res 2010; 179:194-7. [PMID: 20478634 DOI: 10.1016/j.psychres.2009.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 06/23/2009] [Accepted: 06/24/2009] [Indexed: 11/23/2022]
Abstract
The aim of this study was to examine the effects of history of suffocation, state-trait anxiety, and anxiety sensitivity on response to a 35% carbon dioxide (CO₂) challenge in panic disorder patients, their healthy first-degree relatives and healthy comparisons. Thirty-two patients with panic disorder, 32 first-degree relatives, and 34 healthy volunteers underwent the 35% CO₂ challenge. We assessed baseline anxiety with the Anxiety Sensitivity Index (ASI) and State-Trait Anxiety Inventory (STAI1), and panic symptoms with the Panic Symptom List (PSL III-R). A history of suffocation was associated with greater risk of CO₂ reactivity in the combined sample. Patients had more anxiety sensitivity and state and trait anxiety than relatives and healthy comparisons; the difference between relatives and healthy comparisons was not significant. In female patients, trait anxiety predicted CO₂-induced panic. Having a CO₂-sensitive panic disorder patient as a first-degree relative did not predict CO₂-induced panic in a healthy relative. History of suffocation may be an important predictor of CO₂-induced panic. Trait anxiety may have a gender-specific relation to CO₂ reactivity.
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Roberson-Nay R, Klein DF, Klein RG, Mannuzza S, Moulton JL, Guardino M, Pine DS. Carbon dioxide hypersensitivity in separation-anxious offspring of parents with panic disorder. Biol Psychiatry 2010; 67:1171-7. [PMID: 20172505 PMCID: PMC3617557 DOI: 10.1016/j.biopsych.2009.12.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 11/26/2009] [Accepted: 12/11/2009] [Indexed: 10/19/2022]
Abstract
BACKGROUND Similar patterns of vulnerability to carbon dioxide (CO(2)) inhalation have been reported in adults with panic disorder (PD) and children with separation anxiety disorder (SAD), suggesting a link between the adult and child conditions. This study examines the influence of familial risk for PD on CO(2) responses in children with SAD. We hypothesized that offspring with SAD of parents with PD would have distinct CO(2) responses. METHODS Two hundred twelve 9- to 20-year-old offspring of parents with or without PD were exposed to maintained 5% CO(2) inhalation in the participants' homes. Anxiety symptoms, panic attacks, and respiratory physiology (respiratory frequency and tidal volume) were monitored during baseline and 15-min maintained CO(2) breathing. RESULTS As hypothesized, significant offspring SAD x parent PD interactions were obtained for anxiety symptoms, respiratory frequency, tidal volume, and a panting index during CO(2) inhalation. Offspring with both SAD and parental PD exhibited more anxiety symptoms at termination of 5% CO(2) breathing than the other offspring groups and had the most extreme values on measures of respiratory physiology. CONCLUSIONS Youth with both SAD and parental PD have respiratory responses to CO(2) similar to adult PD. They might be a subtype of SAD at particularly high risk for adult PD.
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Affiliation(s)
- Roxann Roberson-Nay
- Virginia Commonwealth University, Department of Psychiatry, Richmond, VA, USA.
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Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies. Int J Psychophysiol 2010; 78:68-79. [PMID: 20685222 DOI: 10.1016/j.ijpsycho.2010.05.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 11/23/2022]
Abstract
Sustained or spontaneous hyperventilation has been associated with a variety of physical symptoms and has been linked to a number of organic illnesses and mental disorders. Theories of panic disorder hold that hyperventilation either produces feared symptoms of hypocapnia or protects against feared suffocation symptoms of hypercapnia. Although the evidence for both theories is inconclusive, findings from observational, experimental, and therapeutic studies suggest an important role of low carbon dioxide (CO2) levels in this disorder. Similarly, hypocapnia and associated hyperpnia are linked to bronchoconstriction, symptom exacerbation, and lower quality of life in patients with asthma. Raising CO2 levels by means of therapeutic capnometry has proven beneficial effects in both disorders, and the reversing of hyperventilation has emerged as a potent mediator for reductions in panic symptom severity and treatment success.
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Sardinha A, Freire RCDR, Zin WA, Nardi AE. Respiratory manifestations of panic disorder: causes, consequences and therapeutic implications. J Bras Pneumol 2010; 35:698-708. [PMID: 19669009 DOI: 10.1590/s1806-37132009000700012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 03/17/2009] [Indexed: 11/22/2022] Open
Abstract
Multiple respiratory abnormalities can be found in anxiety disorders, especially in panic disorder (PD). Individuals with PD experience unexpected panic attacks, characterized by anxiety and fear, resulting in a number of autonomic and respiratory symptoms. Respiratory stimulation is a common event during panic attacks. The respiratory abnormality most often reported in PD patients is increased CO2 sensitivity, which has given rise to the hypothesis of fundamental abnormalities in the physiological mechanisms that control breathing in PD. There is evidence that PD patients with dominant respiratory symptoms are more sensitive to respiratory tests than are those who do not manifest such symptoms, and that the former group constitutes a distinct subtype. Patients with PD tend to hyperventilate and to panic in response to respiratory stimulants such as CO2, triggering the activation of a hypersensitive fear network. Although respiratory physiology seems to remain normal in these subjects, recent evidence supports the idea that they present subclinical abnormalities in respiration and in other functions related to body homeostasis. The fear network, composed of the hippocampus, the medial prefrontal cortex, the amygdala and its brain stem projections, might be oversensitive in PD patients. This theory might explain why medication and cognitive-behavioral therapy are both clearly effective. Our aim was to review the relationship between respiration and PD, addressing the respiratory subtype of PD and the hyperventilation syndrome, with a focus on respiratory challenge tests, as well as on the current mechanistic concepts and the pharmacological implications of this relationship.
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Affiliation(s)
- Aline Sardinha
- Laboratory of Panic and Respiration, Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
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Nardi AE, Freire RC, Zin WA. Panic disorder and control of breathing. Respir Physiol Neurobiol 2009; 167:133-43. [DOI: 10.1016/j.resp.2008.07.011] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 07/15/2008] [Accepted: 07/17/2008] [Indexed: 10/21/2022]
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Wan L, Van Diest I, De Peuter S, Bogaerts K, Van de Woestijne K, Gallego J, Van den Bergh O. Breathlessness rating type influences respiratory behavior during hypercapnia in the rebreathing test. J Psychosom Res 2008; 65:501-4. [PMID: 18940381 DOI: 10.1016/j.jpsychores.2008.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 04/10/2008] [Accepted: 05/05/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The online rating of perceived breathlessness in a rebreathing test (RT) is a new and powerful technique to analyze the psychological and physiological process related to the mechanisms of breathlessness. The aim of the present study was to assess the influence of rating type on respiratory sensation and behavior during repeated hypercapnic exposures. METHODS Sixty-one healthy women performed three rebreathing trials. Half of them were auditorily cued to rate breathlessness intensity every 12 s (CR, n=30), the other half was instructed to rate breathlessness each time a change in breathlessness intensity was perceived (UCR, n=31). The ventilatory response was assessed simultaneously. RESULTS The CR group yielded an earlier threshold in tidal volume (V(T)) than the UCR group. Only in the UCR group did changes occur across rebreathing trials: the V(T) threshold decreased, the respiratory rate (RR) threshold increased, and the sensitivity of the RR increased. CONCLUSIONS The type of breathlessness rating influences respiratory behavior in the RT. The short-interval cued rating seems to be the best option for a standardized application of this test in research on panic disorder.
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Affiliation(s)
- Li Wan
- Department of Psychology, Tiensestraat 102, B-3000 Leuven, Belgium.
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Niccolai V, van Duinen MA, Griez EJ. Objective and subjective measures in recovery from a 35% carbon dioxide challenge. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2008; 53:737-44. [PMID: 19087467 DOI: 10.1177/070674370805301105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES Because hyperventilation, dyspnea, and a feeling of choking are often core features of a panic attack, respiration has been one of the most widely studied physiological parameters in panic disorder (PD) patients. A respiratory subgroup of PD, with distinct etiological pathways, has also been suggested. Investigation of the recovery phase following a respiratory challenge may be a reliable way to establish respiratory impairment in PD patients. The objective of the present study was to investigate the recovery phase from a 35% carbon dioxide challenge in PD patients and in healthy controls, and to test the hypothesis of a different respiratory pattern in patients, compared to control subjects. METHODS Eleven nonmedicated PD patients with or without agoraphobia, 11 medicated PD patients, and 11 control subjects took part in a 35% carbon dioxide and 65% oxygen inhalation challenge. Respiratory rate, partial pressure of carbon dioxide, heart rate, and blood pressure were recorded during the baseline phase (10 minutes) and the recovery phase (10 minutes). Visual Analogue Scale of Anxiety and Panic Symptom List scores were collected pre- and post-challenge. RESULTS Nonmedicated patients had increased variability in respiratory rate and partial pressure of carbon dioxide during recovery, compared with control subjects and medicated PD patients. Also, PD patients tended to have higher heart rates and to need more time to recover from the challenge than control subjects. CONCLUSIONS Results suggest that PD patients have less effective homeostatic control after their physiological equilibrium has been disrupted by a respiratory stressor.
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Affiliation(s)
- Valentina Niccolai
- Academic Anxiety Center, Mondriaan Zorggroep, School of Mental Health and Neurosciences, Maastricht University, Maastricht, The Netherlands
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Abrams K, Schruers K, Cosci F, Sawtell S. Biological challenge procedures used to study co-occurring nicotine dependence and panic disorder. Addict Behav 2008; 33:1463-1469. [PMID: 18400413 DOI: 10.1016/j.addbeh.2008.02.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 02/27/2008] [Accepted: 02/28/2008] [Indexed: 11/15/2022]
Abstract
A wide array of biological challenge procedures - including carbon dioxide inhalation, hyperventilation, and breath holding - have been used to model panic in laboratory settings. Originally used to study developmental processes in panic disorder (PD), these procedures, along with nicotine patch administration and self-administered smoking, have recently been applied to help understand the etiology of co-occurring nicotine dependence and PD. The goals of the present paper are to review studies that have employed biological challenges to study the comorbid condition, identify the advantages and limitations of the various procedures, describe desirable outcome measures for use in biological challenges, and present recommendations for future challenge studies in this field. We argue that biological challenges, though in need of standardization, are useful for studying the development, maintenance, prevention, and treatment of comorbid nicotine dependence and PD.
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Repeated experiences of air hunger and ventilatory behavior in response to hypercapnia in the standardized rebreathing test: effects of anxiety. Biol Psychol 2007; 77:223-32. [PMID: 18077078 DOI: 10.1016/j.biopsycho.2007.10.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Revised: 10/18/2007] [Accepted: 10/29/2007] [Indexed: 11/22/2022]
Abstract
In this study, we assessed air hunger (AH) and ventilatory responses to repeated CO(2) exposures in healthy women (N=31), scoring high or low for trait anxiety. A standardized rebreathing test, implying a gradually increasing CO(2) stimulus, was administered three times with 15-min intervals. Respiratory behavior and the intensity of AH perception were measured continuously. Across repeated exposures, maximal tolerance for AH habituated and the slope of AH (increase in AH per unit increase in CO(2)) diminished. Also the dynamics of the breathing response changed across trials. The thresholds for AH and tidal volume (V(T)) moved closer to each other, whereas the threshold for the respiratory rate (RR) was generally postponed. In addition, the association between AH and V(T) was stronger than between AH and RR, and the latter association became weaker over trials, particularly in high anxious persons. This suggests that AH perception became increasingly influenced by psychological factors, especially in high anxious persons. The results suggest that habituation of perceived air hunger is depending on a complex interplay between both changes in respiratory behavior and in perceptual-cognitive processes related to trait anxiety.
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