Slow recovery from voluntary hyperventilation in panic disorder

High ventilation breathwork practices: An overview of their effects, mechanisms, and considerations for clinical applications

High Ventilation Breathwork (HVB) refers to practices employing specific volitional manipulation of breathing, with a long history of use to relieve various forms of psychological distress. This paper seeks to offer a consolidative insight into potential clinical application of HVB as a treatment of psychiatric disorders. We thus review the characteristic phenomenological and neurophysiological effects of these practices to inform their mechanism of therapeutic action, safety profiles and future clinical applications. Clinical observations and data from neurophysiological studies indicate that HVB is associated with extraordinary changes in subjective experience, as well as with profound effects on central and autonomic nervous systems functions through modulation of neurometabolic parameters and interoceptive sensory systems. This growing evidence base may guide how the phenomenological effects of HVB can be understood, and potentially harnessed in the context of such volitional perturbation of psychophysiological state. Reports of putative beneficial effects for trauma-related, affective, and somatic disorders invite further research to obtain detailed mechanistic knowledge, and rigorous clinical testing of these potential therapeutic uses.

Associations between psychological and respiratory distress in post-deployment Veterans

Since September 11, 2001, over 2.7 million United States service members have deployed to South-West Asia and the Middle East and have been exposed to environmental hazards and psychological trauma. Many of these service members have returned with medical and psychological illnesses, some of which have proved complex and resistant to treatment. One notable constellation of symptoms is post-deployment respiratory illness, which has become a focus of research and policy efforts. The present study sought to examine the impact of post-deployment psychological distress on respiratory symptom severity. Data were obtained from the Veterans Affairs Airborne Hazards and Open Burn Pit Registry (AHOBPR) health surveillance database (N =107,403). Psychological factors were compared against common organic and environmental predictors of post-deployment respiratory distress. Psychological distress following deployment was a stronger predictor of 12-month shortness of breath severity than general respiratory pathology or level of exposure to environmental hazards, controlling for gender, age, race, and tobacco use. Additionally, psychological distress was a better predictor of shortness of breath severity than documented respiratory illnesses including asthma, chronic obstructive pulmonary disease, and chronic bronchitis. Implications and directions for future research are discussed, as well as potential alterations to existing treatment and health surveillance paradigms.

Biological and cognitive theories explaining panic disorder: A narrative review

The current narrative review summarizes and examines several theories of panic disorder (PD) including biological theories, encompassing neurochemical factors, metabolic and genetic theories, respiratory and hyperventilation theories and cognitive theory. Biological theories have informed the development of psychopharmacological treatments; however, they may be limited in their utility given the efficacy of psychological treatments. In particular, behavioral and, more recently, cognitive models have garnered support due to the efficacy of cognitive-behavior therapy (CBT) in treating PD. The role of combination treatments has been found to be superior in the treatment of PD in particular cases, lending support for the need for an integrated approach and model for PD given that the etiology of PD is complex and multifactorial.

The sigh and related behaviors

Breathing is a critical, complex, and highly integrated behavior. Normal rhythmic breathing, also referred to as eupnea, is interspersed with different breathing related behaviors. Sighing is one of such behaviors, essential for maintaining effective gas exchange by preventing the gradual collapse of alveoli in the lungs, known as atelectasis. Critical for the generation of both sighing and eupneic breathing is a region of the medulla known as the preBötzinger Complex (preBötC). Efforts are underway to identify the cellular pathways that link sighing as well as sneezing, yawning, and hiccupping with other brain regions to better understand how they are integrated and regulated in the context of other behaviors including chemosensation, olfaction, and cognition. Unraveling these interactions may provide important insights into the diverse roles of these behaviors in the initiation of arousal, stimulation of vigilance, and the relay of certain behavioral states. This chapter focuses primarily on the function of the sigh, how it is locally generated within the preBötC, and what the functional implications are for a potential link between sighing and cognitive regulation. Furthermore, we discuss recent insights gained into the pathways and mechanisms that control yawning, sneezing, and hiccupping.

Habituation or Normalization? Experiential and Respiratory Recovery From Voluntary Hyperventilation in Treated Versus Untreated Patients With Panic Disorder

Psychophysiological theories postulate respiratory dysregulation as a mechanism contributing to panic disorder (PD). Additionally, symptomatic and respiratory recovery from voluntary hyperventilation (HVT-recovery) have been shown to lag in PD and it is unclear if HVT-recovery normalizes with treatment. Thirty-seven panic disorder patients were randomized to hypoventilation therapy (TX, n = 20) or waitlist control (WL, n = 17) (Meuret et al., 2008). In a secondary analysis, their HVT-recovery was analyzed at pre- and post-TX/WL, compared to 29 healthy controls (HC). HVT included three phases: 5-min baseline, 3-min hyperventilation, and 8-min recovery. HVT-elicited symptom severity and anxiety were rated following each phase, and end-tidal PCO₂ and respiratory rate (RR) were recorded throughout. Treatment, compared to WL, was highly effective in reducing PD pathology (d=2.21, Meuret et al., 2008). At pre-TX/WL, PD demonstrated delayed HVT-recovery PCO₂ and higher RR. Treated patients demonstrated normalization of HVT-recovery for PCO₂ and RR; however, improvements of HVT-recovery for symptom severity and anxiety did not differ between TX and WL. Results replicate pretreatment HVT respiratory recovery abnormalities in PD and further demonstrate normalization, comparable to HC, following successful treatment. The results provide support for respiratory dysregulation as a feature of PD and demonstrate the utility of HVT respiratory recovery as treatment outcome measure for respiration-based PD therapy.

An Anti-hyperventilation Instruction Decreases the Drop in End-tidal CO2 and Symptoms of Hyperventilation During Breathing at 0.1 Hz

Breathing at a frequency of around 0.1 Hz is widely used in basic research and in applied psychophysiology because it strongly increases fluctuations in the cardiovascular system and affects psychological functioning. Volitional control of breathing often leads to hyperventilation among untrained individuals, which may produce aversive symptoms and alter the psychological and physiological effects of the paced breathing. The present study investigated the effectiveness of a brief anti-hyperventilation instruction during paced breathing at a frequency of 0.1 Hz. Forty-six participants were randomly assigned to one of two groups: a group given an anti-hyperventilation instruction and a control group without such an instruction. The instruction asked participants to avoid excessively deep breathing and to breathe shallowly and naturally. Participants performed the breathing task for 10 min. Hyperventilation was measured by partial pressure of end-tidal CO₂ (PetCO₂); furthermore, symptoms of hyperventilation, feeling of air hunger, task difficulty, and affective state were measured by self-report. The results showed that paced breathing without instruction decreased PetCO₂ by 5.21 mmHg and that the use of the anti-hyperventilation instruction reduced the drop in PetCO₂ to 2.7 mmHg. Symptoms of hyperventilation were lower in the group with the anti-hyperventilation instruction. Neither the feeling of air hunger nor task difficulty were affected by the instruction. There were no significant effects of the instruction on affective state. The present study indicates that a brief anti-hyperventilation instruction may be used to decrease drop in PetCO₂ and symptoms of hyperventilation during breathing at 0.1 Hz and that the instruction is well tolerated.

Cognitive Vulnerability in the Context of Panic: Assessment of Panic-Related Associations and Interpretations in Individuals with Varying Levels of Anxiety Sensitivity

Background

Cognitive models of panic disorder (PD) highlight the role of panic-related associations and interpretations. However, results are mixed and rely on specific measures. This study examined panic-related associations and interpretations using established and new paradigms in individuals varying on anxiety sensitivity (AS).

Methods

Associations were measured using a priming task and a novel Single Target Implicit Association Test (STIAT); interpretations were assessed using the Interpretation Bias Questionnaire (IBQ) and a novel Scrambled Sentences Task (SST). Symptoms were assessed via a provocation task (Straw Breathing Task, SBT).

Results

Panic-related interpretations correlated with AS and other PD-related measures. Of the association tasks, only the priming task correlated with one of the other PD-related measures. Panic-related interpretations assessed via the SST, but not priming, STIAT, and IBQ, predicted SBT reactivity. The relationship between AS and SBT reactivity was mediated by panic-related interpretations.

Conclusions

Our data provide support for panic-related interpretations as an important cognitive mechanism.

Habituation of the electrodermal response - A biological correlate of resilience?

Current approaches to quantifying resilience make extensive use of self-reported data. Problematically, this type of scales is plagued by response distortions–both deliberate and unintentional, particularly in occupational populations. The aim of the current study was to develop an objective index of resilience. The study was conducted in 30 young healthy adults. Following completion of the Connor-Davidson Resilience Scale (CD-RISC) and Depression/Anxiety/Stress Scale (DASS), they were subjected to a series of 15 acoustic startle stimuli (95 dB, 50 ms) presented at random intervals, with respiration, skin conductance and ECG recorded. As expected, resilience (CD-RISC) significantly and negatively correlated with all three DASS subscales–Depression (r = -0.66, p<0.0001), Anxiety (r = -0.50, p<0.005) and Stress (r = -0.48, p<0.005). Acoustic stimuli consistently provoked transient skin conductance (SC) responses, with SC slopes indexing response habituation. This slope significantly and positively correlated with DASS-Depression (r = 0.59, p<0.005), DASS-Anxiety (r = 0.35, p<0.05) and DASS-Total (r = 0.50, p<0.005) scores, and negatively with resilience score (r = -0.47; p = 0.006), indicating that high-resilience individuals are characterized by steeper habituation slopes compared to low-resilience individuals. Our key finding of the connection between habituation of the skin conductance responses to repeated acoustic startle stimulus and resilience-related psychometric constructs suggests that response habituation paradigm has the potential to characterize important attributes of cognitive fitness and well-being–such as depression, anxiety and resilience. With steep negative slopes reflecting faster habituation, lower depression/anxiety and higher resilience, and slower or no habituation characterizing less resilient individuals, this protocol may offer a distortion-free method for objective assessment and monitoring of psychological resilience.

The effects of breathing at a frequency of 0.1 Hz on affective state, the cardiovascular system, and adequacy of ventilation

The present study aimed to investigate changes induced by breathing at 0.1 Hz in affective state, cardiovascular activity, and adequacy of ventilation as well as the relation between changes in peripheral physiological processes and alteration of affect. Eighty-three participants were randomly assigned to one of three groups: Two groups doing paced breathing at 0.1 Hz, one with and the other without a cover story hiding the goal of the experiment, and, as a control, paced breathing at 0.28 Hz. We measured the effects of breathing at 0.1 Hz on affective state (unpleasant and pleasant arousals), respiratory sinus arrhythmia (RSA), sympathetic control of the heart (preejection period, PEP), and adequacy of ventilation as measured by partial pressure of end-tidal CO₂ (PetCO₂ ). The use of a cover story did not influence the effects of paced breathing on the study outcomes. In the 0.1 Hz groups, unpleasant arousal decreased only among men. Changes in RSA were not related to changes in affect. Respiratory frequency did not influence PEP. However, changes in PEP were inversely related to changes in pleasant arousal. PetCO₂ decreased in all conditions, and a larger drop in PetCO₂ predicted a greater decrease in unpleasant arousal. The results obtained corroborate previous findings showing that slow paced breathing may lead to moderate hyperventilation among untrained participants and suggest that hyperventilation during breathing at 0.1 Hz is not deep enough to produce an increase in affective arousal.

A sigh of relief or a sigh of expected relief: Sigh rate in response to dyspnea relief

Research has suggested that sighs may serve a regulatory function during stress and emotions by facilitating relief. Evidence supports the hypotheses that sighs both express and induce relief from stress. To explore the potential role of sighs in the regulation of symptoms, the present study aimed to investigate the relationship between sighs and relief of symptoms, and relief of dyspnea, specifically. Healthy volunteers participated in two studies (N = 44, N = 47) in which dyspnea was induced by mild (10 cmH₂ O/l/s) or high (20 cmH₂ 0/l/s) inspiratory resistances. Dyspnea relief was induced by the offset of the inspiratory resistances (transitions from high and mild inspiratory resistance to no resistance). Control comparisons included dyspnea increases (transitions from no or mild inspiratory resistance to high inspiratory resistance) and dyspnea continuations (continuations of either no resistance or a high resistance). In Experiment 1, dyspnea levels were cued. In Experiment 2, no cues were provided. Sigh rate during dyspnea relief was significantly higher compared to control conditions, and sigh rate increased as self-reported dyspnea decreased. Additionally, sigh rate was higher during cued dyspnea relief compared to noncued dyspnea relief. These results suggest that sighs are important markers of dyspnea relief. Moreover, sighs may importantly express dyspnea relief, as they are related to experiential dyspnea decreases and occur more frequently during expected dyspnea relief. These findings suggest that sighs may not only be important in the regulation of stress and emotions, but also may be functional in the regulation of dyspnea.

Sigh rate during emotional transitions: More evidence for a sigh of relief

Evidence suggests that sighs regulate stress and emotions, e.g. by facilitating relief. This study aimed to investigate sigh rates during relief. In addition, links between sighs, anxiety sensitivity and HPA-axis activity were explored. Healthy volunteers (N=29) were presented cues predicting the valence of subsequent stimuli. By sequencing cues that predicted pleasant or unpleasant stimuli with or without certainty, transitions to certain pleasantness (relief) or to certain unpleasantness (control) were created and compared to no transitions. Salivary cortisol, anxiety sensitivity and respiration were measured. Sigh frequency was significantly higher during relief than during control transitions and no transition states, and higher during control transitions than during no transition states. Sigh frequency increased with steeper cortisol declines for high anxiety sensitive persons. Results confirm a relationship between sighs and relief. In addition, results suggest that sigh frequency is importantly related to HPA-axis activity, particularly in high anxiety sensitive persons.

Psychological treatment of comorbid asthma and panic disorder in Latino adults: Results from a randomized controlled trial

Confusion between panic and asthma symptoms can result in serious self-management errors. A cognitive behavior psychophysiological therapy (CBPT) intervention was culturally adapted for Latinos consisting of CBT for panic disorder (PD), asthma education, differentiation between panic and asthma symptoms, and heart rate variability biofeedback. An RCT compared CBPT to music and relaxation therapy (MRT), which included listening to relaxing music and paced breathing at resting respiration rates. Fifty-three Latino (primarily Puerto Rican) adults with asthma and PD were randomly assigned to CBPT or MRT for 8 weekly sessions. Both groups showed improvements in PD severity, asthma control, and several other anxiety and asthma outcome measures from baseline to post-treatment and 3-month follow-up. CBPT showed an advantage over MRT for improvement in adherence to inhaled corticosteroids. Improvements in PD severity were mediated by anxiety sensitivity in CBPT and by depression in MRT, although earlier levels of these mediators did not predict subsequent improvements. Attrition was high (40%) in both groups, albeit comparable to CBT studies targeting anxiety in Latinos. Additional strategies are needed to improve retention in this high-risk population. Both CBPT and MRT may be efficacious interventions for comorbid asthma-PD, and CBPT may offer additional benefits for improving medication adherence.

The role of respiratory measures to assess mental load in pilot selection

While cardiovascular measures have a long tradition of being used to determine operator load, responsiveness of the respiratory system to mental load has rarely been investigated. In this study, we assessed basic and variability measures of respiration rate (RR), partial pressure of end-tidal carbon dioxide (petCO2) as well as performance measures in 63 male pilot candidates during completion of a complex cognitive task and subsequent recovery. Mental load was associated with an increase in RR and a decrease in respiratory variability. A significant decrease was also found for petCO2. RR and respiratory variability showed partial and complete effects of recovery, respectively, whereas petCO2 did not return to baseline level. Overall, a good performance was related to a stronger reactivity in RR. Our findings suggest that respiratory parameters would be a useful supplement to common measures for the assessment of mental load in pilot selection. Practitioner Summary: Respiratory measures are a promising yet poorly investigated approach to monitor operator load. For pilot selection, we assessed respiration in response to multitasking in 63 candidates. Task-related changes as well as covariation with performance strongly support the consideration of respiratory parameters when evaluating reactivity to mental load.

Are respiratory abnormalities specific for panic disorder? A meta-analysis

OBJECTIVES

There is evidence of baseline respiratory abnormalities in panic disorder (PD), but whether they are specific to PD remains unclear. To investigate this issue, we meta-analyzed results from studies comparing baseline respiratory and hematic variables between subjects with PD and subjects with other anxiety disorders.

METHODS

A literature search in bibliographic databases was performed. Fixed-effects models were applied. Several moderator analyses and publication bias diagnostics were performed.

RESULTS

We found: (1) significantly lower mean end-tidal partial pressure of CO(2) (et-pCO(2)) in subjects with PD than in those with social phobia (SP) or generalized anxiety disorder (GAD), and (2) higher mean respiratory rate, lower venous et-pCO(2) and HCO(3)(-) concentration in subjects with PD than in those with SP. No publication bias was found.

CONCLUSIONS

Subjects with PD show a condition of baseline hyperventilation when compared to subjects with SP or GAD. Hematic variables suggest that the hyperventilation may be chronic. These results support the idea that baseline respiratory abnormalities are specific to PD pathophysiology. Further studies are needed to clarify whether these abnormalities are related to a malfunction of the respiratory system or to specific cognitive/emotional/behavioral factors in this population.

Low baseline pCO2 predicts poorer outcome from behavioral treatment: evidence from a mixed anxiety disorders sample

Low levels of end-tidal partial pressure of carbon dioxide (pCO2)-the amount of carbon dioxide measured from expired air-are commonly found in individuals with anxiety disorders but have not been examined as predictors of outcome from anxiety treatment. The current study examined pre-treatment baseline pCO2 as a predictor of outcome from cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) for anxiety disorders. Sixty-one individuals with a Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defined principal anxiety disorder diagnosis completed 12 sessions of either CBT or ACT. Baseline pCO2 was measured prior to entering treatment. Self-reported anxiety symptoms and quality of life were assessed at pre-treatment, post-treatment, and 6- and 12-month follow-up from baseline. Low baseline pCO2 was associated with higher anxiety symptoms and lower quality of life across follow-up timepoints, above and beyond baseline symptom severity. These results suggest that low baseline pCO2 predicts poorer outcome from CBT and ACT for anxiety and may warrant treatment that directly addresses respiratory dysregulation.

Physiological evaluation of psychological treatments for anxiety

Classification of mental disorders has been greatly influenced by a medical model postulating biological abnormalities that underlie its divisions. Particularly in anxiety disorders, physiological symptoms are part of the Diagnostic and Statistical Manual criteria. Therefore, successful therapy should influence physiological as well as cognitive-verbal expressions of anxiety. Nevertheless, despite the well-known limitations of self-report, physiological outcome measures have only occasionally been employed. We searched the literature for treatment studies that attempted to make a physiological argument for the efficacy of a psychological treatment for anxiety. Our search found only a few methodologically sound examples, where normalization of self-report and physiological measures corresponded. The most convincing studies dealt with the treatment of specific phobias and post-traumatic stress disorder.

The integrative role of the sigh in psychology, physiology, pathology, and neurobiology

"Sighs, tears, grief, distress" expresses Johann Sebastian Bach in a musical example for the relationship between sighs and deep emotions. This review explores the neurobiological basis of the sigh and its relationship with psychology, physiology, and pathology. Sighs monitor changes in brain states, induce arousal, and reset breathing variability. These behavioral roles homeostatically regulate breathing stability under physiological and pathological conditions. Sighs evoked in hypoxia evoke arousal and thereby become critical for survival. Hypoarousal and failure to sigh have been associated with sudden infant death syndrome. Increased breathing irregularity may provoke excessive sighing and hyperarousal, a behavioral sequence that may play a role in panic disorders. Essential for generating sighs and breathing is the pre-Bötzinger complex. Modulatory and synaptic interactions within this local network and between networks located in the brainstem, cerebellum, cortex, hypothalamus, amygdala, and the periaqueductal gray may govern the relationships between physiology, psychology, and pathology. Unraveling these circuits will lead to a better understanding of how we balance emotions and how emotions become pathological.

Experiential, autonomic, and respiratory correlates of CO2 reactivity in individuals with high and low anxiety sensitivity

Psychometric studies indicate that anxiety sensitivity (AS) is a risk factor for anxiety disorders such as panic disorder (PD). To better understand the psychophysiological basis of AS and its relation to clinical anxiety, we examined whether high-AS individuals show similarly elevated reactivity to inhalations of carbon dioxide (CO2) as previously reported for PD and social phobia in this task. Healthy individuals with high and low AS were exposed to eight standardized inhalations of 20% CO2-enriched air, preceded and followed by inhalations of room air. Anxiety and dyspnea, in addition to autonomic and respiratory responses were measured every 15 s. Throughout the task, high AS participants showed a respiratory pattern of faster, shallower breathing and reduced inhalation of CO2 indicative of anticipatory or contextual anxiety. In addition, they showed elevated dyspnea responses to the second set of air inhalations accompanied by elevated heart rate, which could be due to sensitization or conditioning. Respiratory abnormalities seem to be common to high AS individuals and PD patients when considering previous findings with this task. Similarly, sensitization or conditioning of anxious and dyspneic symptoms might be common to high AS and clinical anxiety. Respiratory conditionability deserves greater attention in anxiety disorder research.

Responses to voluntary hyperventilation in children with separation anxiety disorder: implications for the link to panic disorder

BACKGROUND

Biological theories on respiratory regulation have linked separation anxiety disorder (SAD) to panic disorder (PD). We tested if SAD children show similarly increased anxious and psychophysiological responding to voluntary hyperventilation and compromised recovery thereafter as has been observed in PD patients.

METHODS

Participants were 49 children (5-14 years old) with SAD, 21 clinical controls with other anxiety disorders, and 39 healthy controls. We assessed cardiac sympathetic and parasympathetic, respiratory (including pCO2), electrodermal, electromyographic, and self-report variables during baseline, paced hyperventilation, and recovery.

RESULTS

SAD children did not react with increased anxiety or panic symptoms and did not show signs of slowed recovery. However, during hyperventilation they exhibited elevated reactivity in respiratory variability, heart rate, and musculus corrugator supercilii activity indicating difficulty with respiratory regulation.

CONCLUSIONS

Reactions to hyperventilation are much less pronounced in children with SAD than in PD patients. SAD children showed voluntary breathing regulation deficits.

Abnormal activity-dependent brain lactate and glutamate+glutamine responses in panic disorder

BACKGROUND

Prior evidence suggests panic disorder (PD) is characterized by neurometabolic abnormalities, including increased brain lactate responses to neural activation. Increased lactate responses could reflect a general upregulation of metabolic responses to neural activation. However, prior studies in PD have not measured activity-dependent changes in brain metabolites other than lactate. Here we examine activity-dependent changes in both lactate and glutamate plus glutamine (glx) in PD.

METHODS

Twenty-one PD patients (13 remitted, 8 symptomatic) and 12 healthy volunteers were studied. A single-voxel, J-difference, magnetic resonance spectroscopy editing sequence was used to measure lactate and glx changes in visual cortex induced by visual stimulation.

RESULTS

The PD patients had significantly greater activity-dependent increases in brain lactate than healthy volunteers. The differences were significant for both remitted and symptomatic PD patients, who did not differ from each other. Activity-dependent changes in glx were significantly smaller in PD patients than in healthy volunteers. The temporal correlation between lactate and glx changes was significantly stronger in control subjects than in PD patients.

CONCLUSIONS

The novel demonstration that glx responses are diminished and temporally decoupled from lactate responses in PD contradicts the model of a general upregulation of activity-dependent brain metabolic responses in PD. The increase in activity-dependent brain lactate accumulation appears to be a trait feature of PD. Given the close relationship between lactate and pH in the brain, the findings are consistent with a model of brain metabolic and pH dysregulation associated with altered function of acid-sensitive fear circuits contributing to trait vulnerability in PD.

Baseline respiratory parameters in panic disorder: a meta-analysis

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.

[Training to management of violence in hospital setting]

OBJECTIVE

Evaluate the typology of violence in hospital setting, study the psychophysiological state of care givers dealing with the aggression and provide appropriate training.

STUDY DESIGN

Single centre, observational.

PATIENTS AND METHODS

A first anonymous questionnaire was given to a sample of emergency and intensive care providers in Narbonne Hospital. The parameters studied included: demographics data, the Trait Anxiety Inventory test, the typology of aggressions, and the psycho-physiological state of subjects dealing with the aggression. Robert Paturel, an instructor of French Special Forces (Recherche-Assistance-Intervention-Dissuasion [RAID]), has provided training for the management of violence. A second questionnaire assessed satisfaction for proposed formation.

RESULTS

Forty-one questionnaires were returned. The rates of verbal and physical violence touching care givers were respectively 97 % and 41 % (median of 7years [1-36] experience on the job). Eighty-five percent of care givers wanted training in psychology of conflict and 93 % wanted a formation with a self-defense aspect. The first reason of violence was drugs and alcohol abuse. The "tunnel effect" during stress was identified in 34 % of care givers, and 20 % were unaware of its nature. Twenty-one percent of care givers spontaneously adopting a safe distance of more than 1m during a conflict had been physically assaulted versus 63 % for those staying less than 1m (P=0.03). The proposed formation, including psychology of conflict and self-defense, was satisfactory to all care givers who participated (median score 9/10 [7-10]).

CONCLUSION

The verbal and physical violence affecting emergency departments is a common phenomenon warranting appropriate training. The proposed formation included the comprehension of the conflict causality, self-defense and self-control.

Respiratory variability and sighing: a psychophysiological reset model

Whereas respiratory psychophysiological research has mainly studied respiratory time and volume, variability in these parameters has been largely disregarded, even though it may provide important information about respiratory regulation. The present paper reviews the literature on respiratory variability and elaborates on the importance of assessing various components of respiratory variability when studying the interrelationships between emotions and breathing. A model is proposed that predicts specific action tendencies related to emotions to disturb the balance between various respiratory variability components depending on valence by arousal and control dimensions. The central focus of the paper is sighing. The causes and consequences of sighing are reviewed and integrated in the proposed model in which sighing is hypothesized to function as a resetter in the regulation of both breathing and emotions, because it restores a balance in respiratory variability fractions and causes relief.

Which symptoms matter? Self-report and observer discrepancies in repressors and high-anxious women with metastatic breast cancer

Clinicians working with cancer patients listen to them, observe their behavior, and monitor their physiology. How do we proceed when these indicators do not align? Under self-relevant stress, non-cancer repressors respond with high arousal but report low anxiety; the high-anxious report high anxiety but often have lower arousal. This study extends discrepancy research on repressors and the high-anxious to a metastatic breast cancer sample and examines physician rating of coping. Before and during a Trier Social Stress Test (TSST), we assessed affect, autonomic reactivity, and observers coded emotional expression from TSST videotapes. We compared non-extreme (N = 40), low-anxious (N = 16), high-anxious (N = 19), and repressors (N = 19). Despite reported low anxiety, repressors expressed significantly greater Tension or anxiety cues. Despite reported high anxiety, the high-anxious expressed significantly greater Hostile Affect rather than Tension. Physicians rated both groups as coping significantly better than others. Future research might productively study physician-patient interaction in these groups.

Hyperventilation in anticipatory music performance anxiety

OBJECTIVES AND METHODS

Self-report studies have shown an association between music performance anxiety (MPA) and hyperventilation complaints. However, hyperventilation was never assessed physiologically in MPA. This study investigated the self-reported affective experience, self-reported physiological symptoms, and cardiorespiratory variables including partial pressure of end-tidal CO(2) (Petco(2)), which is an indicator for hyperventilation, in 67 music students before a private and a public performance. The response coherence between these response domains was also investigated.

RESULTS

From the private to the public session, the intensity of all self-report variables increased (all p values < .001). As predicted, the higher the musician's usual MPA level, the larger were these increases (p values < .10). With the exception of Petco(2), the main cardiorespiratory variables also increased from the private to the public session (p values < .05). These increases were not modulated by the usual MPA level (p values > .10). Petco(2) showed a unique response pattern reflected by an MPA-by-session interaction (p < .01): it increased from the private to the public session for musicians with low MPA levels and decreased for musicians with high MPA levels. Self-reported physiological symptoms were related to the self-reported affective experience (p values < .05) rather than to physiological measures (p values > .17).

CONCLUSIONS

These findings show for the first time how respiration is stimulated before a public performance in music students with different MPA levels. The hypothesis of a hyperventilation tendency in high-performance-anxious musicians is supported. The response coherence between physiological symptoms and physiological activation is weak.

Coping skills and exposure therapy in panic disorder and agoraphobia: latest advances and future directions

Although cognitive-behavioral treatments for panic disorder have demonstrated efficacy, a considerable number of patients terminate treatment prematurely or remain symtpomatic. Cognitive and biobehavioral coping skills are taught to improve exposure therapy outcomes but evidence for an additive effect is largely lacking. Current methodologies used to study the augmenting effects of coping skills test the degree to which the delivery of coping skills enhances outcomes. However, they do not assess the degree to which acquisition of coping skills and their application during exposure therapy augment outcomes. We examine the extant evidence on the role of traditional coping skills in augmenting exposure for panic disorder, discuss the limitations of existing research, and offer recommendations for methodological advances.

Does fear reactivity during exposure predict panic symptom reduction?

OBJECTIVE

Fear reactivity during exposure is a commonly used indicator of learning and overall therapy outcome. The objective of this study was to assess the predictive value of fear reactivity during exposure using multimodal indicators and an advanced analytical design. We also investigated the degree to which treatment condition (cognitive training vs. respiratory skill training) moderated fear reactivity and therapeutic outcome.

METHOD

Thirty-four patients with panic disorder and agoraphobia completed a total of 123 in-vivo exposure sessions, comprising 3 weekly sessions and a 4th session 2 months following therapy completion. Sessions varied in length and phobic stimuli. Cardiorespiratory physiology (heart rate, carbon dioxide partial pressure [PCO2], respiration rate) and experiential symptoms (panic symptoms and anxiety) were assessed repeatedly throughout exposure sessions, in addition to weekly assessments of panic cognitions, avoidance, and functioning.

RESULTS

Panic symptomatology decreased substantially in both treatment conditions during therapy and follow-up. Significant cardiorespiratory and experiential reactivity was observed during all exposures, characterized by activation followed by reduction. Greater within-session activation of anxiety and panic symptoms was inversely related to improvement in panic symptoms severity, but neither physiological activation nor within- or between-session reduction of either physiological or experiential variables was predictive of outcome. No moderating effects of treatment condition were found.

CONCLUSIONS

Fear activation and reduction during exposure are weak predictors of corrective learning and fear extinction. Clinical implications for exposure therapy and directions for future research are discussed.

Perceived and physiological arousal during a stress task: can they differentiate between anxiety and depression?

BACKGROUND

Anxiety and depression might be two different valid constructs that often co-occur, or they could be different manifestations of the same underlying vulnerability. A theoretical framework to address this question is the tripartite model, by Clark and Watson, which hypothesizes that physiological hyperarousal (PH) is specific for anxiety. Knowledge about the relationship between PH, psychophysiological measures, perceived arousal, and anxiety would increase our understanding of the validity of the PH construct in this model. Our objective was to assess whether (a) hypothalamic-pituitary-adrenocortical (HPA) axis functioning, and (b) perceived arousal before, during and after stress can differentiate anxious from depressive children.

METHODS

In a general population sample of 225 children aged 8-12 years, self-reported anxiety and depressive symptoms were assessed using the Multidimensional Anxiety Scale for Children (MASC) and the Children's Depression Inventory (CDI). Perceived arousal was assessed using a self-report questionnaire before, during and after a stress task. Basal and reactive HPA-axis functioning were used as indices for psychophysiological arousal.

RESULTS

Our data showed that the relation between perceived arousal and anxiety problems is stronger than the relation with depressive problems. Reactive HPA-axis functioning is reduced in children with depressive problems.

CONCLUSIONS

Some evidence was found in support of the tripartite model. Our findings indicate that perceived arousal to a challenge might be a useful tool to assess the PH component of the tripartite model. Reactive HPA-axis functioning might be able to differentiate between anxiety and depressive problems in children in a general population sample, but effect sizes are small and replication is needed.

Temporal stability and coherence of anxiety, dyspnea, and physiological variables in panic disorder

Twenty-five panic disorder (PD) patients, 19 social phobics (SP), and 20 healthy controls (HC) sat quietly for 15 min, rating their anxiety and dyspnea every 30s while respiratory, cardiovascular, and electrodermal responses were recorded. No panic attacks were reported. For self-reported anxiety and dyspnea, within-subject variability over time was higher in PD than in SP or HC. In PD within-subject correlations across 30-s epochs were significant for (a) self-reported anxiety versus dyspnea, end-tidal pCO2, minute volume, duty cycle, skin conductance level, and interbeat interval, and for (b) dyspnea versus end-tidal pCO2, minute volume, tidal volume, and inspiratory flow rate. Several positive or negative correlations were greater in PD than in other groups. Thus in PD, experienced anxiety and dyspnea are temporally unstable but are correlated with each other and with fluctuations in respiratory and autonomic variables, even in the absence of panic attacks.

The psychophysiology of blood-injection-injury phobia: looking beyond the diphasic response paradigm

Blood-injection-injury (BII) phobia is an anxiety disorder that may be accompanied by vasovagal fainting during confrontation with the feared stimuli. The underlying pattern of autonomic regulation has been characterized as a diphasic response, with initial increases in heart rate and blood pressure that are typical of a fight-flight response, and subsequent drops in blood pressure and/or heart rate that may precipitate vasovagal fainting. Tensing skeletal muscles of the arms, legs, and trunk (applied tension) has been proposed as a technique to cope with this dysregulation. This review critically examines the empirical basis for the diphasic response and its treatment by applied tension in BII phobia. An alternative perspective on the psychophysiology of BII phobia and vasovagal fainting is offered by focusing on hypocapnia that leads to cerebral blood flow reductions, a perspective supported by research on neurocardiogenic and orthostatically-induced syncope. The evidence may indicate a role for respiration-focused coping techniques in BII phobia.

Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies

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.

Acids in the brain: a factor in panic?

Several methods to experimentally induce panic cause profound acid-base disturbances. Evidence suggests that CO(2) inhalations, lactate infusions and, to a certain extent, voluntary hyperventilation can conceivably lead to a common scenario of brain acidosis in the face of disparate intravascular pH alterations. The importance of this event is reflected in data that support a model in which experimental panic attacks, as proxy to those occurring spontaneously, constitute a response to acute brain acidosis. Given that central CO(2)/H(+) chemoreception is an important drive for ventilation, and many chemosensitive neurons are related to respiration and arousal, this model can explain much of the connection between panic and respiration. We propose that the shared characteristics of CO(2)/H(+) sensing neurons overlap to a point where threatening disturbances in brain pH homeostasis, such as those produced by CO(2) inhalations, elicit a primal emotion that can range from breathlessness to panic.

Take a deep breath: the relief effect of spontaneous and instructed sighs

Spontaneous sighing is related to subjective relief of negative emotional states. Whether this also applies to instructed sighing is not known. The present study aimed to investigate sEMG and respiratory variability (1) during recovery from mental stress with and without an instructed sigh; (2) before and after spontaneous sighs throughout the experiment. A spontaneous sigh was preceded by increasing sEMG and increasing random respiratory variability, and followed by decreasing sEMG and increased structured correlated respiratory variability. Following an instructed sigh, a smaller reduction in sEMG and an increase in random respiratory variability during recovery from mental stress were observed. Thus, a spontaneous sigh seemed to induce relief. An instructed sigh appeared to inhibit recovery from mental stress.

Change point analysis for longitudinal physiological data: detection of cardio-respiratory changes preceding panic attacks

Statistical methods for detecting changes in longitudinal time series of psychophysiological data are limited. ANOVA and mixed models are not designed to detect the existence, timing, or duration of unknown changes in such data. Change point (CP) analysis was developed to detect distinct changes in time series data. Preliminary reports using CP analysis for fMRI data are promising. Here, we illustrate the application of CP analysis for detecting discrete changes in ambulatory, peripheral physiological data leading up to naturally occurring panic attacks (PAs). The CP method was successful in detecting cardio-respiratory changes that preceded the onset of reported PAs. Furthermore, the changes were unique to the pre-PA period, and were not detected in matched non-PA control periods. The efficacy of our CP method was further validated by detecting patterns of change that were consistent with prominent respiratory theories of panic positing a relation between aberrant respiration and panic etiology.

Respiratory, autonomic, and experiential responses to repeated inhalations of 20% CO₂ enriched air in panic disorder, social phobia, and healthy controls

Inhalation of carbon dioxide (CO₂) enriched air triggers anxiety in panic disorder (PD) patients, which is often interpreted as a sign of biological vulnerability. However, most studies have not measured respiration in these tasks. We compared patients with PD (n=20) and social phobia (SP, n=19) to healthy controls (n=18) during eight inhalations of 20% CO₂, preceded and followed by two inhalations of room air, while continuously measuring subjective anxiety and dyspnea as well as autonomic and respiratory variables. PD patients showed increased reactivity and delayed recovery during CO₂ inhalations for most measures. Unlike both other groups, the PD group's tidal volume responses did not habituate across CO₂ inhalations. However, PD patients did not differ from SP patients on most other measures, supporting a continuum model of CO₂ sensitivity across anxiety disorders. Both patient groups showed continued reactivity during the last air inhalations, which is unlikely to be due to a biological sensitivity.

Respiratory variability preceding and following sighs: a resetter hypothesis

Respiratory behavior is characterized by complex variability with structured and random components. Assuming that both a lack of variability and too much randomness represent suboptimal breathing regulation, we hypothesized that sighing acts as a resetter inducing structured variability. Spontaneous breathing was measured in healthy persons (N=42) during a 20min period of quiet sitting using the LifeShirt(®) System. Four blocks of 10 breaths with a 50% window overlap were determined before and after spontaneous sighs. Total respiratory variability of minute ventilation was measured using the coefficient of variation and structured (correlated) variability was quantified using autocorrelation. Towards a sigh, total variability gradually increased without concomittant changes in correlated variability, suggesting that randomness increased. After a sigh, correlated variability increased. No changes in variability were found in comparable epochs without intermediate sighs. We conclude that a sigh resets structured respiratory variability, enhancing information processing in the respiratory system.

Respiratory patterns in panic disorder reviewed: a focus on biological challenge tests

OBJECTIVE

To provide a systematic review of studies investigating respiration in PD and comments on relative inconsistencies.

METHOD

A Medline search of controlled studies focusing on pCO(2), respiratory rate, tidal volume, and minute volume in PD patients was conducted for baseline/resting condition, challenge, and recovery phase. Respiratory variability and comparisons between panickers and non-panickers were also examined.

RESULTS

Lower pCO(2) levels in PD subjects are a consistent finding during the baseline/resting condition, the challenge, and recovery phases. Tidal volume and minute volume are increased in PD subjects relative to controls during the baseline/resting condition. However, the most robust finding is a higher than normal respiratory variability, which appears to be a promising factor for the identification of respiratory etiopathological pathways in PD.

CONCLUSION

Respiratory variability might be a candidate for a biological marker of PD: an abnormal breathing pattern as found in panic disorder (PD) patients compared with controls might indicate instability of the respiratory homeostasis.

Research applications of magnetic resonance spectroscopy to investigate psychiatric disorders

Advances in magnetic resonance spectroscopy (MRS) methodology and related analytic strategies allow sophisticated testing of neurobiological models of disease pathology in psychiatric disorders. An overview of principles underlying MRS, methodological considerations, and investigative approaches is presented. A review of recent research is presented that highlights innovative approaches applying MRS, in particular, hydrogen MRS, to systematically investigate specific psychiatric disorders, including autism spectrum disorders, schizophrenia, panic disorder, major depression, and bipolar disorder.

Changes in respiration mediate changes in fear of bodily sensations in panic disorder

The purpose of the study was to examine whether changes in pCO(2) mediate changes in fear of bodily sensation (as indexed by anxiety sensitivity) in a bio-behavioral treatment for panic disorder that targets changes in end-tidal pCO(2). Thirty-five panic patients underwent 4 weeks of capnometry-assisted breathing training targeting respiratory dysregulation. Longitudinal mediation analyses of the changes in fear of bodily symptoms over time demonstrated that pCO(2), but not respiration rate, was a partial mediator of the changes in anxiety sensitivity. Results were supported by cross lag panel analyses, which indicated that earlier pCO(2) levels predicted later levels of anxiety sensitivity, but not vice versa. PCO(2) changes also led to changes in respiration rate, questioning the importance of respiration rate in breathing training. The results provide little support for changes in fear of bodily sensations leading to changes in respiration, but rather suggest that breathing training targeting pCO(2) reduced fear of bodily sensations in panic disorder.

Hypocapnia increases the prevalence of hypoxia-induced augmented breaths

Augmented breaths promote respiratory instability and have been implicated in triggering periods of sleep-disordered breathing. Since respiratory instability is well known to be exacerbated by hypocapnia, we asked whether one of the destabilizing effects of hypocapnia might be related to an increased prevalence of augmented breaths. With this question in mind, we first sought to determine whether hypoxia-induced augmented breaths are more prevalent when hypocapnia is also present. To do this, we studied the breath-by-breath ventilatory responses of a group of freely behaving adult rats in a variety of different respiratory background conditions. We found that the prevalence of augmented breaths was dramatically increased during hypocapnic-hypoxia compared with room air conditions. When hypocapnia was prevented during exposure to hypoxia by adding 5% CO2 to the inspired air, the rate of occurrence of augmented breaths was no greater than that observed in room air. The addition of CO2 alone to room air had no effect on the prevalence of augmented breaths. We conclude that in spontaneously breathing rats, hypoxia promotes the generation of augmented breaths, but only in poikilocapnic conditions, where hypocapnia develops. Our results, therefore, reveal a means by which CO2 exerts a stabilizing influence on breathing, which may be of particular relevance during sleep in conditions commonly associated with respiratory instability.

Objective and subjective measures in recovery from a 35% carbon dioxide challenge

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.

Biological challenge procedures used to study co-occurring nicotine dependence and panic disorder

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.