Resting end-tidal CO2 and negative affectivity

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 .

Dyspnea related to reversibly-binding P2Y12 inhibitors: A review of the pathophysiology, clinical presentation and diagnostics

Dyspnea is a common symptom physiologically associated with strenuous exercise and pathologically reflecting well-known diseases and conditions that are predominantly pulmonary, cardiovascular, and weight-related in origin. Dyspnea improves with appropriate measures that enhance physical performance and treatment of the underlying diseases. Dyspnea is less commonly triggered by other causes such as the environment (e.g., ozone), drugs, and others, some of which do not seem to affect bronchopulmonary function as evidenced by normal results of comprehensive pulmonary function testing. In cardiovascular medicine, dyspnea has recently attracted attention because it has been reported that this symptom occurs more frequently with the administration of the new oral reversibly-binding platelet P2Y12 receptor inhibitors ticagrelor [1-6], cangrelor [7-10], and elinogrel [11]. This paper succinctly addresses the current understanding of the pathophysiology, clinical presentation, and diagnostics of dyspnea, associated either with bronchopulmonary function impairment, as triggered mainly by pulmonary and cardiovascular diseases, or without bronchopulmonary function impairment, as induced by endogenous or external compounds such as drugs in order to provide a context for understanding, recognizing and managing P2Y12 inhibitor-induced dyspnea.

Different patterns of respiration in rat lines selectively bred for high or low anxiety

In humans, there is unequivocal evidence of an association between anxiety states and altered respiratory function. Despite this, the link between anxiety and respiration has been poorly evaluated in experimental animals. The primary objective of the present study was to investigate the hypothesis that genetic lines of rats that differ largely in their anxiety level would display matching alterations in respiration. To reach this goal, respiration was recorded in high-anxiety behavior (HAB, n = 10) and low-anxiety behavior (LAB, n = 10) male rats using whole-body plethysmography. In resting state, respiratory rate was higher in HABs (85 ± 2 cycles per minute, cpm) than LABs (67 ± 2 cpm, p<0.05). During initial testing into the plethysmograph and during a restraint test, HAB rats spent less time at high-frequency sniffing compared to LAB rats. In addition, HAB rats did not habituate in terms of respiratory response to repetitive acoustic stressful stimuli. Finally, HAB rats exhibited a larger incidence of sighs during free exploration of the plethysmograph and under stress conditions. We conclude that: i) HAB rats showed respiratory changes (elevated resting respiratory rate, reduced sniffing in novel environment, increased incidence of sighs, and no habituation of the respiratory response to repetitive stimuli) that resemble those observed in anxious and panic patients, and ii) respiratory patterns may represent a promising way for assessing anxiety states in preclinical studies.

Aerodynamic profiles of women with muscle tension dysphonia/aphonia

PURPOSE

In this study, the authors aimed to (a) determine whether phonatory airflows and estimated subglottal pressures (est-Psub) for women with primary muscle tension dysphonia/aphonia (MTD/A) differ from those for healthy speakers; (b) identify different aerodynamic profile patterns within the MTD/A subject group; and (c) determine whether results suggest new understanding of pathogenesis in MTD/A.

METHOD

Retrospective review of aerodynamic data collected from 90 women at the time of primary MTD/A diagnosis.

RESULTS

Aerodynamic profiles were significantly different for women with MTD/A as compared with healthy speakers. Five distinct profiles were identified: (a) normal flow, normal est-Psub; (b) high flow, high est-Psub; (c) low flow, normal est-Psub; (d) normal flow, high est-Psub; and (e) high flow, normal est-Psub.

CONCLUSIONS

This study is the first to identify distinct subgroups of aerodynamic profiles in women with MTD/A and to quantitatively identify a clinical phenomenon sometimes described in association with it-"breath holding"-that is shown by low airflow with normal est-Psub. Results were consistent with clinical claims that diverse respiratory and laryngeal functions may underlie phonatory patterns associated with MTD/A. One potential mechanism, based in psychobiological theory, is introduced to explain some of the variability in aerodynamic profiles of women with MTD/A.

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.

Differentiation between the sensory and affective aspects of histamine-induced bronchoconstriction in asthma

Respiratory symptom perception research has focused mainly on respiratory sensations. Because dyspnea is multidimensional, affective aspects should be investigated. Patients with asthma (N=25) underwent a histamine provocation until a 20% fall in forced expiratory volume in 1s (FEV(1)). After each dose level, 6 symptoms of dyspnea intensity and 6 symptoms of dyspnea affectivity were rated. Individual perceptual sensitivity was determined by calculating the linear slope between the fall in FEV(1) and the increase in the total symptom score, and for affective and sensory symptoms separately [Bijl-Hofland, Folgering, van den Hoogen, et al. Perception of bronchoconstriction in asthma patients measured during histamine challenge test. Eur Respir J 1999;14:1049-54]. Trait anxiety, baseline state anxiety, daily asthma symptoms and catastrophizing during an asthma exacerbation were also assessed. Sensitivity was unrelated to physiological indices of disease severity (i.e., baseline FEV(1) and histamine dose level at 20% fall in FEV(1)), whereas it was positively related to trait anxiety, state anxiety, daily asthma symptoms and catastrophic thinking during an asthma exacerbation in daily life. These relationships were overall much stronger for affective than for sensory symptom slopes. In stepwise multiple regressions, state anxiety was the best predictor of the affective symptom slopes, whereas catastrophic thinking during an asthma exacerbation was the best predictor for the sensory symptom slopes. The differentiation between sensory and affective components of dyspnea adds to the understanding of respiratory symptom perception in asthma.

Anxiety and respiratory variability

Associations of inter- and intra-individual differences in anxiety and fear with within subject variability in breathing parameters were explored. Timing and volume components of respiration and FETCO(2) were measured non-intrusively before and during anxious and fearful imagery in 98 young women. Trait anxiety was associated with less variability in several breathing parameters during baseline preceding imagery. Significant decreases in the variability of expiratory time and inspiratory drive were also observed during anxious imagery. During fearful imagery, however, the variability of FETCO(2) increased compared to baseline. Results on anxiety are largely in agreement with models that posit that healthy systems are characterized by variability and flexibility. The paradoxical findings for fearful imagery enhance the importance of a distinction between fearful and anxious affects.

Imagined risk of suffocation as a trigger for hyperventilation

OBJECTIVE

Although hyperventilation has been hypothesized to play a role in many pathologies, its critical triggers remain poorly understood. The present experiment aimed to test whether stronger hyperventilation responses occur in response to suggested risk of suffocation compared with other fearful situations in high- and low-trait anxious women.

METHODS

Fractional end-tidal CO2-concentration (FetCO2), respiratory frequency, and inspiratory volume were measured nonintrusively in high- (n = 24) and low- (n = 24) trait anxious women during imagery of 3 fear, 1 tension, 1 depressive, and 3 relaxation scripts. The fear scripts were equal in ratings of unpleasantness and arousal but differed regarding the inclusion of suggested risk of suffocation and entrapment. After each imagery trial, participants rated the emotional dimensions of pleasantness, arousal, and dominance and the vividness of their imagery.

RESULTS

Decreases in FetCO2 occurred in all fear scripts. High-trait anxious women showed a stronger reduction in FetCO2 compared with low-trait anxious women during the fear script suggesting risk of suffocation but not during the other fear scripts. This effect was unrelated to any of the self-reported fear ratings. Self-reported fear of entrapment was associated with an overall lower FetCO2 but not with enhanced reactivity to imagined entrapment.

CONCLUSION

High-trait anxiety is associated with stronger respiratory responsivity to imagined risk of suffocation and may constitute a specific vulnerability factor for the development of panic disorder and claustrophobia.

Accuracy of respiratory symptom perception in different affective contexts

OBJECTIVE

The accuracy of respiratory symptom perception was investigated in different affective contexts in participants (N=48) scoring high or low for negative affectivity (NA).

METHODS

Within-subject correlations were calculated between two subjective ratings and their respective physiological referent (the rating of "deeper breathing" and respiratory volume, and rating of "faster breathing" and breathing frequency) across nine consecutive breathing trials. Three different air mixtures were used: room air, air enriched with 7.5% CO(2), and with 10% CO(2). For half the participants, the trials were framed in a pleasant context, created by adding a pleasant odour to the air mixture in addition to information announcing pleasant feelings as a result of breathing the air mixtures. The other half received the trials in a distressing context: A foul smelling odour was added and the information announced unpleasant feelings.

RESULTS

High-NA persons were overall less accurate than were low-NA persons in the perception of respiratory volume. For breathing frequency, high-NA persons were significantly less accurate in the distressing condition than in the pleasant one, whereas for low-NA persons, the information frame did not matter.

CONCLUSION

The study shows that the accuracy of respiratory symptom reports is reduced in high-NA persons, especially in a distressing context.

Dyspnea: the role of psychological processes

Breathlessness or dyspnea-the subjective experience of breathing discomfort-is a symptom in many pulmonary, cardiovascular, and neuromuscular diseases. It occurs in normals as well during intense emotional states and heavy labor or exercise. In clinical cases, it generally causes severe suffering. Dyspnea has multifactorial causes and the explanation for the symptom may differ largely among patients. Explanatory models imply the involvement of mechanisms at several levels of functioning, such as afferent signals from the respiratory muscles or blood gas levels related to hypercapnia and hypoxia. Depending on the relative involvement of specific mechanisms and their interactions, dyspnea may be experienced differently and subtypes can be distinguished. More recently, perceptual-cognitive and emotional processes related to symptom perception and interpretation have been investigated in the context of dyspnea. In this review, we focus on the psychological processes that play part in the perception of dyspnea and formulate some practical guidelines for those who are confronted with dyspnea.