Automatic Detection of Dyspnea in Real Human-Robot Interaction Scenarios

A respiratory distress estimation technique for telephony previously proposed by the authors is adapted and evaluated in real static and dynamic HRI scenarios. The system is evaluated with a telephone dataset re-recorded using the robotic platform designed and implemented for this study. In addition, the original telephone training data are modified using an environmental model that incorporates natural robot-generated and external noise sources and reverberant effects using room impulse responses (RIRs). The results indicate that the average accuracy and AUC are just 0.4% less than those obtained with matched training/testing conditions with simulated data. Quite surprisingly, there is not much difference in accuracy and AUC between static and dynamic HRI conditions. Moreover, the beamforming methods delay-and-sum and MVDR lead to average improvement in accuracy and AUC equal to 8% and 2%, respectively, when applied to training and testing data. Regarding the complementarity of time-dependent and time-independent features, the combination of both types of classifiers provides the best joint accuracy and AUC score.

Dyspnea Severity Assessment Based on Vocalization Behavior with Deep Learning on the Telephone

In this paper, a system to assess dyspnea with the mMRC scale, on the phone, via deep learning, is proposed. The method is based on modeling the spontaneous behavior of subjects while pronouncing controlled phonetization. These vocalizations were designed, or chosen, to deal with the stationary noise suppression of cellular handsets, to provoke different rates of exhaled air, and to stimulate different levels of fluency. Time-independent and time-dependent engineered features were proposed and selected, and a k-fold scheme with double validation was adopted to select the models with the greatest potential for generalization. Moreover, score fusion methods were also investigated to optimize the complementarity of the controlled phonetizations and features that were engineered and selected. The results reported here were obtained from 104 participants, where 34 corresponded to healthy individuals and 70 were patients with respiratory conditions. The subjects' vocalizations were recorded with a telephone call (i.e., with an IVR server). The system provided an accuracy of 59% (i.e., estimating the correct mMRC), a root mean square error equal to 0.98, false positive rate of 6%, false negative rate of 11%, and an area under the ROC curve equal to 0.97. Finally, a prototype was developed and implemented, with an ASR-based automatic segmentation scheme, to estimate dyspnea on line.

Clinical Evaluation of Deployed Military Personnel With Chronic Respiratory Symptoms: Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III

BACKGROUND

Chronic respiratory symptoms are frequently reported after Southwest Asia deployment in support of combat operations. The full spectrum of clinical lung diseases related to these deployments is not well characterized.

METHODS

Military personnel with chronic symptoms, primarily exertional dyspnea, underwent a standardized cardiopulmonary evaluation at two tertiary medical centers. Pulmonary function testing consisted of spirometry, lung volume, diffusing capacity, impulse oscillometry, and bronchodilator testing. Further testing included methacholine challenge, exercise laryngoscopy, high-resolution CT scan, ECG, and transthoracic echocardiography.

RESULTS

A total of 380 participants with a mean age of 38.5 ± 8.4 years completed testing. Asthma was the most common diagnosis in 87 patients (22.9%) based on obstructive spirometry/impulse oscillometry and evidence of airway hyperreactivity, whereas another 57 patients (15.0%) had reactivity with normal spirometry. Airway disorders included 25 (6.6%) with laryngeal disorders and 16 (4.2%) with excessive dynamic airway collapse. Interstitial lung disease was identified in six patients (1.6%), whereas 11 patients (2.9%) had fixed obstructive lung disorders. Forty patients (10.5%) had isolated pulmonary function abnormalities and 16 (4.2%) had miscellaneous disorders. The remaining 122 patients (32.1%) with normal studies were classified as undiagnosed exertional dyspnea. Significant comorbidities identified included elevated BMI > 30 kg/m² (34.2%), smoking (36.4%), positive allergy testing (43.7%), sleep apnea (38.5%), and esophageal reflux (13.6%). Mental health disorders and posttraumatic stress disorder were likewise common.

CONCLUSIONS

Postdeployment pulmonary evaluation should focus on common diseases, such as asthma and airway hyperreactivity, and include testing for upper airway disorders. Diffuse lung diseases were rarely diagnosed, whereas numerous comorbidities were common.

The Effects of Repeated Dyspnea Exposure on Response Inhibition

In order to treat dyspnea (=breathlessness) successfully, response inhibition (RI) as a major form of self-regulation is a premise. This is supported by research showing that self-regulation is associated with beneficial behavioral changes supporting treatment success in patients. Recent research showed that dyspnea has an impairing effect on RI, but the effects of repeated dyspnea exposure on RI remain unknown. Therefore, the present study tested the effects of repeated resistive load-induced dyspnea on RI over a 5-day period. Healthy volunteers (n = 34) performed the standard version of the Stroop task during baseline and dyspnea conditions on the first and fifth testing day and underwent an additional dyspnea exposure phase on each testing day. Variables of interest to investigate RI were reaction time, accuracy as well as the event-related potentials late positive complex (LPC) and N400 in the electroencephalogram. Reduced accuracy for incongruent compared to congruent stimuli during the dyspnea condition on the first testing day were found (p < 0.001). This was paralleled by a reduced LPC and an increased N400 for incongruent stimuli during the induction of dyspnea (p < 0.05). After undergoing dyspnea exposure, habituation of dyspnea intensity was evident. Importantly, on the fifth testing day, no differences between baseline, and dyspnea conditions were found for behavioral and electrophysiological measures of RI. These findings demonstrate that the impairing effect of dyspnea on RI disappeared after repeated dyspnea exposure in healthy participants. Translated to a clinical sample, it might cautiously be suggested that dyspnea exposure such as dyspnea perceived during physical exercise could reduce the impairing effect of dyspnea on RI which might have the potential to help increase self-regulation abilities and subsequent treatment efforts in dyspneic patients.

The Impact of Unpredictability on Dyspnea Perception, Anxiety and Interoceptive Error Processing

Dyspnea is a prevalent interoceptive sensation and the aversive cardinal symptom in many cardiorespiratory diseases as well as in mental disorders. Especially the unpredictability of the occurrence of dyspnea episodes has been suggested to be highly anxiety provoking for affected patients. Moreover, previous studies demonstrated that unpredictable exteroceptive stimuli increased self-reports and electrophysiological responses of anxiety such as the startle probe N100 as well as amplified the processing of errors as reflected by greater error-related negativity (ERN). However, studies directly examining the role of unpredictability on dyspnea perception, anxiety, and error processing are widely absent. Using high-density electroencephalography, the present study investigated whether unpredictable compared to predictable dyspnea would increase the perception of dyspnea, anxiety and interoceptive error processing. Thirty-two healthy participants performed a respiratory forced choice reaction time task to elicit an interoceptive ERN during two conditions: an unpredictable and a predictable resistive load-induced dyspnea condition. Predictability was manipulated by pairing (predictable condition) or not pairing (unpredictable condition) dyspnea with a startle tone probe. Self-reports of dyspnea and affective state as well as the startle probe N100 and interoceptive ERN were measured. The results demonstrated greater dyspnea unpleasantness in the unpredictable compared to the predictable condition. Post hoc analyses revealed that this was paralleled by greater anxiety, and greater amplitudes for the startle probe N100 and the interoceptive ERN during the unpredictable relative to the predictable condition, but only when the unpredictable condition was experienced in the first experimental block. Furthermore, higher trait-like anxiety sensitivity was associated with higher ratings for dyspnea unpleasantness and experimental state anxiety ratings. The present findings suggest that unpredictability increases the perception of dyspnea unpleasantness. This effect seems related to increased state and trait anxiety and interoceptive error processing, especially when upcoming dyspnea is particularly unpredictable, such as in early experimental phases. Future studies are required to further substantiate these findings in patients suffering from dyspnea.

[Pulmonary function testing of dyspnea complaint by the pulmonologist]

Dyspnea results from an imbalance between ventilatory demand (linked to CO₂ production, PaCO₂ set-point and wasted ventilation-physiological dead space) and ventilatory capacity (linked to passive-compliance, resistance-and active-respiratory muscles-components of the respiratory system). Spirometry and static lung volumes investigate ventilatory capacity only. Ventilatory demand (increased for instance in all pulmonary vascular diseases due to increased physiological dead space) is not evaluated by these routine measurements. DLCO measurement, which evaluates both demand and capacity, depicts the best statistical correlation to dyspnea, for instance in obstructive and interstitial pulmonary diseases. Dyspnea has multiple domains and is inherently complex and weakly explained by resting investigations: explained variance is below 50%. The diagnostic strategy investigating dyspnea has to distinguish complaints related or not to exercise because dyspnea can occur independently from any effort. Cardiopulmonary exercise testing (V'O2, V'CO2, V'E and operating lung volumes measurements) allows the assessment of underlying pathophysiological mechanisms leading to functional impairment and can contribute to unmask potential underlying mechanisms of unexplained dyspnea although its "etiological diagnostic value" for dyspnea remains a challenging issue.

Increased physiological dead space at exercise is a marker of mild pulmonary or cardiovascular disease in dyspneic subjects

Background: The characteristics of cardiopulmonary exercise testing (CPET)-derived parameters for the differential diagnosis of exertional dyspnea are not well known.

Objectives: We hypothesized that increased physiological dead space ventilation (VD/Vt) is a marker for mild pulmonary or cardiovascular disease in patients with exertional dyspnea.

Design: We used receiver operating characteristic analysis to determine the performance of individual CPET parameters for identifying subjects with either mild pulmonary or cardiovascular disease, among 77 subjects with mild-to-moderate exertional dyspnea (modified Medical Research Council scale 1–2).

Results: In comparison with subjects without disease, subjects with pulmonary disease (n = 31) had higher VE/V′CO₂ slope, higher VD/Vt, and lower ventilatory reserve. Subjects with cardiovascular disease (n = 14) had lower heart rate and cardiovascular double product and higher VD/Vt at peak exercise. At a threshold of 28%, the sensitivity and specificity of VD/Vt at peak exercise for identifying pulmonary or cardiovascular disease were 89% (95% CI: 64–98%) and 72% (95% CI: 46–89%), respectively.

Conclusions: Increased physiological VD/Vt at exercise is a sensitive and specific marker of mild pulmonary or cardiovascular disease in dyspneic subjects.

Retrospective memory for symptoms in patients with medically unexplained symptoms

OBJECTIVE

Clinical assessment and diagnostic processes heavily rely on memory-based symptom reports. The current study investigated memory for symptoms and the peak-end effect for dyspnea in patients with medically unexplained symptoms and healthy participants.

METHODS

Female patients with medically unexplained dyspnea (MUD) (n=22) and matched healthy controls (n=22) participated in two dyspnea induction trials (short, long). Dyspnea ratings were collected: (1) continuously during symptom induction (concurrent with respiratory measures), (2) immediately after the experiment, and (3) after 2weeks. Symptoms, negative affect, and anxiety were assessed at baseline and after every trial. The mediating role of state anxiety in symptom reporting was assessed. The peak-end effect was tested with forced-choice questions measuring relative preference for the trials.

RESULTS

Compared to controls, dyspnea induction resulted in higher levels of symptoms, anxiety, concurrent dyspnea ratings, and minute ventilation in the patient group. In both groups, immediate retrospective ratings were higher than averaged concurrent ratings. No further increase in dyspnea ratings was observed at 2-week recall. Retrospective dyspnea ratings were mediated by both state anxiety and concurrent dyspnea ratings. Patients did not show a peak-end effect, whereas controls did.

CONCLUSION

The findings show that patients' experience of a dyspneic episode is subject to immediate memory bias, but does not change over a longer time period. The results also highlight the importance of affective state during symptom experience for both symptom perception and memory.

The Specificity of Health-Related Autobiographical Memories in Patients With Somatic Symptom Disorder

OBJECTIVE

Patients with somatic symptom disorder (SSD) have persistent distressing somatic symptoms that are associated with excessive thoughts, feelings, and behaviors. Reduced autobiographical memory specificity (rAMS) is related to a range of emotional disorders and is considered a vulnerability factor for an unfavorable course of pathology. The present study investigated whether the specificity of health-related autobiographical memories is reduced in patients with SSD with medically unexplained dyspnea complaints, compared with healthy controls.

METHODS

Female patients with SSD (n = 30) and matched healthy controls (n = 24) completed a health-related Autobiographical Memory Test, the Beck Depression Inventory, the Ruminative Response Scale, and rumination scales concerning bodily reactions. Depressive symptoms and rumination were assessed because both variables previously showed associations with rAMS.

RESULTS

Patients with SSD recalled fewer specific (F(1,52) = 13.63, p = .001) and more categoric (F(1,52) = 7.62, p = .008) autobiographical memories to health-related cue words than healthy controls. Patients also reported higher levels of depressive symptoms and rumination (all t > 3.00, p < .01). Importantly, the differences in memory specificity were independent of depressive symptoms and trait rumination.

CONCLUSIONS

The present study extends findings on rAMS to a previously unstudied sample of patients with SSD. Importantly, the presence of rAMS could not be explained by increased levels of depressive symptoms and rumination. We submit that rAMS in this group reflects how health-related episodes and associated symptoms are encoded in memory.

Accuracy and bias in retrospective symptom reporting

PURPOSE OF REVIEW

Self-reported bodily symptoms are of primary importance in healthcare and in health-related research. Typically, they are assessed in clinical interviews or by means of traditional questionnaire formats that require the respondent to provide retrospective symptom estimates rated along intuitive frequency and/or intensity standards and aggregated across varying or unspecified time windows.

RECENT FINDINGS

Retrospective symptom assessments are often biased when compared to (averaged) momentary assessments of symptoms. A variety of factors and conditions have been identified to influence the amount of bias in symptom reporting. Recent research has focused on the underlying mechanisms for the discrepancy between memory and experience. It is suggested that different types of questions and formats assess different types of information, and each may be relevant for different purposes. Knowledge of these underlying mechanisms also provides a relevant framework to better understand individual differences in symptom reporting, including somatoform and somatic symptom disorder.

SUMMARY

Accuracy of self-reported bodily symptoms is important for the clinician and the researcher. Understanding the mechanisms underlying bias may provide an interesting window to understand how symptom episodes are processed, encoded, and consolidated in memory and may also provide clues to modify symptom experiences.

Brain mechanisms of short-term habituation and sensitization toward dyspnea

Dyspnea is a prevalent and threatening cardinal symptom in many diseases including asthma. Whether patients suffering from dyspnea show habituation or sensitization toward repeated experiences of dyspnea is relevant for both quality of life and treatment success. Understanding the mechanisms, including the underlying brain activation patterns, that determine the dynamics of dyspnea perception seems crucial for the improvement of treatment and rehabilitation. Toward this aim, we investigated the interplay between short-term changes of dyspnea perception and changes of related brain activation. Healthy individuals underwent repeated blocks of resistive load induced dyspnea with parallel acquisition of functional magnetic resonance imaging data. Late vs. early ratings on dyspnea intensity and unpleasantness were correlated with late vs. early brain activation for both, dyspnea anticipation and dyspnea perception. Individual trait and state anxiety were determined using questionnaire data. Our results indicate an involvement of the orbitofrontal cortex (OFC), midbrain/periaqueductal gray (PAG) and anterior insular cortex in habituation/sensitization toward dyspnea. Changes in the anterior insular cortex were particularly linked to changes in dyspnea unpleasantness. Changes of both dyspnea intensity and unpleasantness were positively correlated with state and trait anxiety. Our findings are in line with the suggested relationship between the anterior insular cortex and dyspnea unpleasantness. They further support the notion that habituation/sensitization toward dyspnea is influenced by anxiety. Our study extends the known role of the midbrain/PAG in anti-nociception to an additional involvement in habituation/sensitization toward dyspnea and suggests an interplay with the OFC.

Study of active duty military for pulmonary disease related to environmental deployment exposures (STAMPEDE)

RATIONALE

Because of increased levels of airborne particulate matter in Southwest Asia, deployed military personnel are at risk for developing acute and chronic lung diseases. Increased respiratory symptoms are reported, but limited data exist on reported lung diseases.

OBJECTIVES

To evaluate new respiratory complaints in military personnel returning from Southwest Asia to determine potential etiologies for symptoms.

METHODS

Returning military personnel underwent a prospective standardized evaluation for deployment-related respiratory symptoms within 6 months of returning to their duty station.

MEASUREMENTS AND MAIN RESULTS

Prospective standardized evaluation included full pulmonary function testing, high-resolution chest tomography, methacholine challenge testing, and fiberoptic bronchoscopy with bronchoalveolar lavage. Other procedures including lung biopsy were performed if clinically indicated. Fifty patients completed the study procedures. A large percentage (42%) remained undiagnosed, including 12% with normal testing and an isolated increase in lavage neutrophils or lymphocytes. Twenty (40%) patients demonstrated some evidence of airway hyperreactivity to include eight who met asthma criteria and two with findings secondary to gastroesophageal reflux. Four (8%) additional patients had isolated reduced diffusing capacity and the remaining six had other miscellaneous airway disorders. No patients were identified with diffuse parenchymal disease on the basis of computed tomography imaging. A significant number (66%) of this cohort had underlying mental health and sleep disorders.

CONCLUSIONS

Evaluation of new respiratory symptoms in military personnel after service in Southwest Asia should focus on airway hyperreactivity from exposures to higher levels of ambient particulate matter. These patients may be difficult to diagnose and require close follow-up.

Geriatric dyspnea: doing worse, feeling better

Older age is associated with a decline in physical fitness and reduced efficiency of the respiratory system. Paradoxically, it is also related to reduced report of dyspnea, that is, the experience of difficult and uncomfortable breathing. Reduced symptom reporting contributes to misdiagnosis or late diagnosis of underlying disease, suboptimal treatment, faster disease progression, shorter life expectancy, lower quality of life for patients, and considerably increased costs for the health care system in an aging society. However, pathways in the complex relationship between dyspnea and age are not well explored yet. We propose a model on geriatric dyspnea that integrates physiological, neurological, psychological and social pathways which link older age with dyspnea perception and expression. We suggest that the seemingly paradox of reduction of dyspnea in older age, despite physiological decline, can be solved by taking age-related changes on these multiple levels into account. In identifying these variables, the Geriatric Dyspnea Model highlights risk factors for reduced dyspnea perception and report in older age and pathways for intervention.

Severely impaired health-related quality of life in chronic hyperventilation patients: exploratory data

Patients with hyperventilation syndrome (HVS) report severe symptom-related suffering and often complain from insufficient medical attention. However, quality of life data in this context are scarce. We aimed at assessing the health-related quality of life (HRQoL) of HVS patients. Twenty-one HVS patients with extensive cardiorespiratory workup including cardiopulmonary exercise testing (CPET) filled in the generic SF-36 questionnaire and the results were compared to French normal values. Correlations between SF36 dimensions and clinical and functional data were established. All SF-36 scores were markedly decreased in HVS patients compared to healthy subjects: Physical Functioning: 44 ± 24, Social Functioning: 57 ± 27, Role Physical: 21 ± 32, Role Emotional: 48 ± 42, Mental Health: 51 ± 27, Vitality: 34 ± 20, Body Pain: 41 ± 21, General Health: 42 ± 21. These figures were all significantly lower in the HVS patients respective to the normal reference population. They were also lower than corresponding values published in patients with asthma or chronic obstructive pulmonary disease (COPD). "Vitality" and "Physical Functioning" scores were correlated with Nijmegen score (r = -0.594, p = 0.047) and peak respiratory frequency during CPET (r = -0.644, p = 0.019). The SF-36 Social Functioning score was correlated with the ventilatory threshold (r = 0.629, p = 0.034), peak V'E/V'CO2 (ventilation/CO2 production) (r = 0.650, p = 0.016) and peak PaCO2 (r = -0.664, p = 0.027). In conclusion, this study shows that HRQoL can be severely impaired in patients with HVS, which is one more reason to take this condition seriously.

Control and sensation of breathing during cycling exercise in hypoxia under naloxone: a randomised controlled crossover trial

Background

Opioid receptors are possibly involved in the perception of exertion and the ventilatory response to exercise. We compared incremental cycling exercise in conditions of normoxia and hypoxia (11% O₂) after injection of the opioid receptor antagonist naloxone (30 mg i.v.) or placebo. Naloxone was expected to increase sensation of breathing and cycling and to curtail exercise performance more in hypoxia.

Methods

Ten healthy subjects (29 ± 2 years, 183 ± 6 cm, 75 ± 7 kg, mean ± SD) cycled in normoxia and hypoxia until voluntary exhaustion, receiving naloxone or placebo in a balanced double-blind crossover design.

Results

Hypoxia decreased peak power output by 37%–39% with placebo and naloxone (P < 0.001, no effect of naloxone). Switching to normoxia at exhaustion in hypoxia allowed continuing up to 97%–100% of power developed in normoxia with placebo and naloxone (P < 0.001, no effect of naloxone). Perceived exertion increased in hypoxia, dropped upon switching to normoxia and increased again towards exhaustion, no effect of naloxone. SpO₂ (earlobe oximetry) was lower in hypoxia, dropping to 64%–68% with naloxone and placebo. The ventilatory response to exercise in normoxia and hypoxia was not changed by naloxone.

Conclusions

It follows that in healthy subjects the ventilatory response and the perception of exertion in hypoxia as compared to normoxia do not involve the endogenous opioid system, and the latter does not play a role in limiting maximum exercise capacity in hypoxia.

On the psychology of cough

Neurobiological research is increasingly documenting the role of higher brain areas in cough, but little systematic behavioral research on the role of psychological factors exists. In this article we discuss the role of perceptual, attentional, cognitive, and emotional factors, learning mechanisms, self-regulation, and the role of social context. We also describe how interactions among these mechanisms can help to shed light on idiopathic cough and on placebo/nocebo effects on cough. This functional-behavioral perspective may lay the groundwork for a structured research program on the role of psychological factors in cough.