Respiratory muscle tension as symptom generator in individuals with high anxiety sensitivity

Biobehavioral approach to distinguishing panic symptoms from medical illness

Panic disorder is a common psychiatric diagnosis characterized by acute, distressing somatic symptoms that mimic medically-relevant symptoms. As a result, individuals with panic disorder overutilize personal and healthcare resources in an attempt to diagnose and treat physical symptoms that are often medically benign. A biobehavioral perspective on these symptoms is needed that integrates psychological and medical knowledge to avoid costly treatments and prolonged suffering. This narrative review examines six common somatic symptoms of panic attacks (non-cardiac chest pain, palpitations, dyspnea, dizziness, abdominal distress, and paresthesia), identified in the literature as the most severe, prevalent, or critical for differential diagnosis in somatic illness, including long COVID. We review somatic illnesses that are commonly comorbid or produce panic-like symptoms, their relevant risk factors, characteristics that assist in distinguishing them from panic, and treatment approaches that are typical for these conditions. Additionally, this review discusses key factors, including cultural considerations, to assist healthcare professionals in differentiating benign from medically relevant symptoms in panic sufferers.

Breathing on the mind: Treating dyspnea and anxiety symptoms with biofeedback in chronic lung disease - A qualitative analysis

RATIONALE

Chronic obstructive pulmonary disease (COPD) is characterized by dysfunctional breathing patterns that contribute to impaired lung function and symptoms of dyspnea, anxiety, and abnormal carbon dioxide (CO2) levels.

OBJECTIVE

The study objective was to measure the acceptability of a new mind-body intervention we developed called Capnography-Assisted, Learned Monitored (CALM) Breathing, implemented before pulmonary rehabilitation.

METHODS

CALM Breathing is a 4-week (8-session) intervention designed to treat dyspnea and anxiety in adults with COPD by targeting dysfunctional breathing behaviors (guided by end-tidal CO2 levels). CALM Breathing consists of ten core breathing exercises, CO2 biofeedback, and motivational interviewing. Using qualitative methods and semi-structured interviews immediately post-intervention, we evaluated the acceptability and participation process of CALM Breathing. Themes were identified using constant comparative analysis.

RESULTS

Sixteen participants were interviewed after receiving CALM Breathing. Three main themes of CALM Breathing were identified: (1) Process of learning self-regulated breathing, (2) Mechanisms of a mind-body intervention, (3) Clinical and implementation outcomes.

CONCLUSIONS

Positive themes supported the acceptability of CALM Breathing and described participants' process of learning more self-regulated breathing to manage their dyspnea and anxiety. Positive signals from qualitative participant feedback provided support for CALM Breathing as an intervention for COPD, but larger scale efficacy trials are needed.

Biofeedback Training to Increase P co2 in Asthma With Elevated Anxiety: A One-Stop Treatment of Both Conditions?

OBJECTIVE

Anxiety is highly prevalent in individuals with asthma. Asthma symptoms and medication can exacerbate anxiety, and vice versa. Unfortunately, treatments of comorbid anxiety and asthma are largely lacking. A problematic feature common to both conditions is hyperventilation. It adversely affects lung function and symptoms in asthma and anxiety. We examined whether a treatment to reduce hyperventilation, shown to improve asthma symptoms, also improves anxiety in asthma patients with high anxiety.

METHOD

One hundred twenty English- or Spanish-speaking adult patients with asthma were randomly assigned to either Capnometry-Assisted Respiratory Training (CART) to raise P co2 or feedback to slow respiratory rate (SLOW). Although anxiety was not an inclusion criterion, 21.7% met clinically relevant anxiety levels on the Hospital Anxiety and Depression Scale (HADS). Anxiety (HADS-A) and depression (HADS-D) scales, anxiety sensitivity (Anxiety Sensitivity Index [ASI]), and negative affect (Negative Affect Scale of the Positive Affect Negative Affect Schedule) were assessed at baseline, posttreatment, 1-month follow-up, and 6-month follow-up.

RESULTS

In this secondary analysis, asthma patients with high baseline anxiety showed greater reductions in ASI and PANAS-N in CART than in SLOW ( p values ≤ .005, Cohen d values ≥ 0.58). Furthermore, at 6-month follow-up, these patients also had lower ASI, PANAS-N, and HADS-D in CART than in SLOW ( p values ≤ .012, Cohen d values ≥ 0.54). Patients with low baseline anxiety did not have differential outcomes in CART than in SLOW.

CONCLUSIONS

For asthma patients with high anxiety, our brief training designed to raise P co2 resulted in significant and sustained reductions in anxiety sensitivity and negative affect compared with slow-breathing training. The findings lend support for P co2 as a potential physiological target for anxiety reduction in asthma.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT00975273 .

Acceptability of capnography-assisted respiratory therapy: a new mind-body intervention for COPD

Dyspnoea self-management is often suboptimal for patients with COPD. Many patients with COPD experience chronic dyspnoea as distressing and disabling, especially during physical activities. Breathing therapy is a behavioural intervention that targets reducing the distress and impact of dyspnoea on exertion in daily living. Using a qualitative design, we conducted interviews with 14 patients after they participated in a novel mind-body breathing therapy intervention adjunct, capnography-assisted respiratory therapy (CART), combined with outpatient pulmonary rehabilitation. Comprehensive CART consisted of patient-centred biofeedback, tailored breathing exercises, a home exercise programme and motivational interviewing counselling. We assessed participants' perceptions and reported experiences to gauge the acceptability of CART and refine CART based on feedback. Constant comparative analysis was used to identify commonalities and themes. We identified three main themes relating to the acceptability and reported benefits of CART: (1) self-regulating breathing; (2) impact on health; and (3) patient satisfaction. Our findings were used to refine and optimise CART (i.e. its intensity, timing and format) for COPD. By addressing dysfunctional breathing behaviours and dysregulated interoception, CART offers a promising new paradigm for relieving dyspnoea and related anxiety in patients with COPD.

Respiratory therapy for the treatment of anxiety: Meta-analytic review and regression

OBJECTIVE

Respiratory abnormalities are a hallmark of anxiety symptomatology and may serve as clinically useful modifiers for alleviating anxiety symptoms. However, gold-standard anxiety treatments (e.g., cognitive-behavioral interventions) often do not directly address respiratory components despite their theoretical utility and clinical accessibility. This review examined the clinical effectiveness of respiratory interventions, interventions that directly target respiration abnormalities and processes, in treating trait anxiety symptoms.

METHODS

The final analysis included 40 randomized controlled trials including at least one measure of trait anxiety, a respiratory-focused intervention group, and a non-respiratory control-group (active or inactive treatment). Overall effects of respiratory focused interventions were examined, as well as the effect of hypothesized moderators.

RESULTS

Respiratory component interventions yielded significantly greater improvements (moderate to large effect) in anxiety symptoms than controls, with the stronger effects observed in comparison to inactive, rather than active, control conditions. Significant heterogeneity in findings suggests that variability in intervention design, population, and control comparison may obfuscate interpretation of findings.

CONCLUSIONS

Evidence supports the clinical utility of respiratory interventions as either an independent anxiety treatment, or as an adjunct to other interventions. Clinical and research implications of findings along with recommendations for ongoing investigations in this domain are discussed.

Cardiopulmonary exercise testing for identification of patients with hyperventilation syndrome

Introduction

Measurement of ventilatory efficiency, defined as minute ventilation per unit carbon dioxide production (V_E/VCO₂), by cardiopulmonary exercise testing (CPET) has been proposed as a screen for hyperventilation syndrome (HVS). However, increased V_E/VCO₂ may be associated with other disorders which need to be distinguished from HVS. A more specific marker of HVS by CPET would be clinically useful. We hypothesized ventilatory control during exercise is abnormal in patients with HVS.

Methods

Patients who underwent CPET from years 2015 through 2017 were retrospectively identified and formed the study group. HVS was defined as dyspnea with respiratory alkalosis (pH >7.45) at peak exercise with absence of acute or chronic respiratory, heart or psychiatric disease. Healthy patients were selected as controls. For comparison the Student t-test or Mann-Whitney U test were used. Data are summarized as mean ± SD or median (IQR); p<0.05 was considered significant.

Results

Twenty-nine patients with HVS were identified and 29 control subjects were selected. At rest, end-tidal carbon dioxide (P_ETCO₂) was 27 mmHg (25–30) for HVS patients vs. 30 mmHg (28–32); in controls (p = 0.05). At peak exercise P_ETCO₂ was also significantly lower (27 ± 4 mmHg vs. 35 ± 4 mmHg; p<0.01) and V_E/VCO₂ higher ((38 (35–43) vs. 31 (27–34); p<0.01)) in patients with HVS. In contrast to controls, there were minimal changes of P_ETCO₂ (0.50 ± 5.26 mmHg vs. 6.2 ± 4.6 mmHg; p<0.01) and V_E/VCO₂ ((0.17 (-4.24–6.02) vs. -6.6 (-11.4-(-2.8)); p<0.01)) during exercise in patients with HVS. The absence of V_E/VCO₂ and P_ETCO₂ change during exercise was specific for HVS (83% and 93%, respectively).

Conclusion

Absence of V_E/VCO₂ and P_ETCO₂ change during exercise may identify patients with HVS.

Mental load during cognitive performance in complex regional pain syndrome I

BACKGROUND

Complex regional pain syndrome (CRPS) is associated with deficits in limb recognition. The purpose of our study was to determine whether mental load during this task affected performance, sympathetic nervous system activity or pain in CRPS patients.

METHODS

We investigated twenty CRPS-I patients with pain in the upper extremity and twenty age- and sex-matched healthy controls. Each participant completed a limb recognition task. To experimentally manipulate mental load, the presentation time for each picture varied from 2 s (greatest mental load), 4, 6 to 10 s (least mental load). Before and after each run, pain intensity was assessed. Skin conductance was recorded continuously.

RESULTS

Patients with CRPS did not differ from controls in terms of limb recognition and skin conductance reactivity. However, patients with CRPS reported an increase in pain during the task, particularly during high mental load and during the latter stages of the task. Interestingly, state anxiety and depressive symptoms were also associated with increases in pain intensity during high mental load.

CONCLUSIONS

These findings indicate that high mental load intensifies pain in CRPS. The increase of pain in association with anxiety and depression indicates a detrimental effect of negative affective states in situations of high stress and mental load in CRPS.

SIGNIFICANCE

The effects of mental load need to be considered when patients with CRPS-I are investigated for diagnostic or therapeutic reasons.

Effects of respiratory and applied muscle tensing interventions on responses to a simulated blood draw among individuals with high needle fear

Fear of blood and needles increases risk for presyncopal symptoms. Applied muscle tension can prevent or attenuate presyncopal symptoms; however, it is not universally effective. This study examined the effects of applied muscle tension, a respiratory intervention, and a no treatment control condition, on presyncopal symptoms and cerebral oxygenation, during a simulated blood draw with individuals highly fearful of needles. Participants (n = 95) completed questionnaires, physiological monitoring, and two trials of a simulated blood draw with recovery. Presyncopal symptoms decreased across trials; however, no group differences emerged. Applied muscle tension was associated with greater cerebral oxygenation during trial two, and greater end-tidal carbon dioxide during both trials. The respiratory intervention did not differ from the no treatment control. Applied muscle tension is an intervention that can increase cerebral oxygenation and end-tidal carbon dioxide. While the respiratory intervention is promising within therapeutic settings, it was not efficacious after a brief audio training.

Hypoventilation Therapy Alleviates Panic by Repeated Induction of Dyspnea

BACKGROUND

Previous research has shown that hypoventilation therapy reduces panic symptoms in part by increasing basal partial pressure of carbon dioxide (PCO₂) levels. We tested an additional pathway by which hypoventilation therapy could exert its therapeutic effects: through repeated interoceptive exposure to sensations of dyspnea.

METHODS

A total of 35 patients with panic disorder were trained to perform exercises to raise their end-tidal PCO₂ levels using a portable capnometry device. Anxiety, dyspnea, end-tidal PCO₂, and respiratory rate were assessed during each exercise across 4 weeks of training. Mixed-model analysis examined whether within-exercise levels of dyspnea were predictive of reduction of panicogenic cognitions.

RESULTS

As expected, within-exercise anxiety and respiratory rate decreased over time. Unexpectedly, PCO₂ dropped significantly from the beginning to the end of exercise, with these drops becoming progressively smaller across weeks. Dyspnea increased and remained consistently above basal levels across weeks. As hypothesized, greater dyspnea was related to significantly lower panicogenic cognitions over time even after controlling for anxiety and PCO₂. Additional exploratory analyses showed that within-exercise increases in dyspnea were related to within-exercise increases in anxiety but were not related to within-exercise increases in PCO₂.

CONCLUSIONS

In support of the interoceptive exposure model, we found that greater dyspnea during hypoventilation exercises resulted in lower panicogenic cognitions even after the effect of PCO₂ was taken into account. The findings offer an additional important target in panic treatment.

Breathing training for dysfunctional breathing in asthma: taking a multidimensional approach

Various breathing training programmes may be helpful for adults with asthma. The main therapeutic aim for many of these programmes is the correction of dysfunctional breathing. Dysfunctional breathing can be viewed practically as a multidimensional entity with the three key dimensions being biochemical, biomechanical and psychophysiological. The objectives of this review are to explore how each of these dimensions might impact on asthma sufferers, to review how various breathing therapy protocols target these dimensions and to determine if there is evidence suggesting how breathing therapy protocols might be optimised. Databases and reference lists of articles were searched for peer-reviewed English language studies that discussed asthma or dysfunctional breathing and various breathing therapies. Biochemical, biomechanical and psychophysiological aspects of dysfunctional breathing can all potentially impact on asthma symptoms and breathing control. There is significant variation in breathing training protocols and the extent to which they evaluate and improve function in these three dimensions. The various dimensions of dysfunctional breathing may be of greater or lesser importance in different cases and the effectiveness of breathing training protocols is likely to be improved when all three dimensions are considered. Outcomes for breathing training for dysfunctional breathing in asthma may be most successful when the three key dimensions of dysfunctional breathing are evaluated at the start of treatment and monitored during treatment. This allows breathing training protocols to be adjusted as appropriate to ensure that treatment is sufficiently comprehensive and intensive to produce measurable improvements where necessary.

When dyspnea gets worse: Suffocation fear and the dynamics of defensive respiratory responses to increasing interoceptive threat

In patients with anxiety and/or respiratory diseases, body sensations, particularly from the respiratory system, may increase in intensity and aversiveness and thus lead into defensive action (e.g., escape) or panic. The processes, however, that might contribute to the culmination of symptoms and the switch into defensive action have not been well understood yet. The current study aimed at evaluating an experimental paradigm to characterize the dynamics of defensive mobilization to body sensations increasing in intensity and aversiveness. Persons reporting low and high suffocation fear (SF; N = 69) were exposed to increasingly unpleasant feelings of dyspnea induced by inspiratory resistive loads and a breathing occlusion requiring voluntary breath holding. Respiratory responses were assessed along with subjective reports of anxiety and panic symptoms. Presentation of respiratory loads with increasing physical resistance led to increasingly unpleasant feelings of dyspnea. Twenty-eight participants terminated the exposure prematurely at least once. When dyspnea was severe, high compared to low SF persons exhibited an increased respiratory rate that was accompanied by reports of more intense panic symptoms. Premature terminations of exposure were preceded by a surge in anxiety, breathing frequency, and mouth pressure, and a decrease in tidal volume. We successfully established an experimental paradigm to assess changes in defensive responding with increasing intensity of an interoceptive threat. The current data foster our understanding of behavioral expression patterns observed in patients with anxiety and/or respiratory diseases and the processes involved in the culmination of bodily sensations and anxiety into panic.

Panic Disorder Comorbidity with Medical Conditions and Treatment Implications

Panic disorder (PD) is unique among the anxiety disorders in that panic symptoms are primarily of a physical nature. Consequently, comorbidity with medical illness is significant. This review examines the association between PD and medical illness. We identify shared pathophysiological and psychological correlates and illustrate how physiological activation in panic sufferers underlies their symptom experience in the context of the fight-or-flight response and beyond a situation-specific response pattern. We then review evidence for bodily symptom perception accuracy in PD. Prevalence of comorbidity for PD and medical illness is presented, with a focus on respiratory and cardiovascular illness, irritable bowel syndrome, and diabetes, followed by an outline for potential pathways of a bidirectional association. We conclude by illustrating commonalities in mediating mechanistic pathways and moderating risk factors across medical illnesses, and we discuss implications for diagnosis and treatment of both types of conditions.

Can Interoception Improve the Pragmatic Search for Biomarkers in Psychiatry?

Disrupted interoception is a prominent feature of the diagnostic classification of several psychiatric disorders. However, progress in understanding the interoceptive basis of these disorders has been incremental, and the application of interoception in clinical treatment is currently limited to panic disorder. To examine the degree to which the scientific community has recognized interoception as a construct of interest, we identified and individually screened all articles published in the English language on interoception and associated root terms in Pubmed, Psychinfo, and ISI Web of Knowledge. This search revealed that interoception is a multifaceted process that is being increasingly studied within the fields of psychiatry, psychology, neuroscience, and biomedical science. To illustrate the multifaceted nature of interoception, we provide a focused review of one of the most commonly studied interoceptive channels, the cardiovascular system, and give a detailed comparison of the most popular methods used to study cardiac interoception. We subsequently review evidence of interoceptive dysfunction in panic disorder, depression, somatic symptom disorders, anorexia nervosa, and bulimia nervosa. For each disorder, we suggest how interoceptive predictions constructed by the brain may erroneously bias individuals to express key symptoms and behaviors, and outline questions that are suitable for the development of neuroscience-based mental health interventions. We conclude that interoception represents a viable avenue for clinical and translational research in psychiatry, with a well-established conceptual framework, a neural basis, measurable biomarkers, interdisciplinary appeal, and transdiagnostic targets for understanding and improving mental health outcomes.

Subjective ratings of prolonged inspiratory resistive loaded breathing in males and females

Dyspnea and fear of suffocation are burdensome to patients with respiratory disease. Inspiratory resistive loads offer an experimental respiratory stimulus to quantify the discriminative domain of respiratory perception. Resistive (R) load magnitude estimation (ME) and subjective ratings were measured over sustained multiple breaths in healthy subjects. There was no significant group difference between the ME for Breath 1 and 20 for small R loads, but a significant gender difference for large R loads. Subjective responses of fear, fear of suffocation, displeasure, chest pressure, faintness, dizziness, fear of losing control, trembling, and tingling were significantly greater for females. These results demonstrate that ME of large resistive sustained loads elicits nonsignificant increases in ME in females, but a significant decrease in ME for males. The maintenance of ME in females co-occurs with increased aversive processing relative to males.