Dyspnea relief: More than just the perception of a decrease in dyspnea

Sensory interventions to relieve dyspnoea in critically ill mechanically ventilated patients

BACKGROUND

In critically ill patients receiving mechanical ventilation, dyspnoea is frequent, severe and associated with an increased risk of neuropsychological sequelae. We evaluated the efficacy of sensory interventions targeting the brain rather than the respiratory system to relieve dyspnoea in mechanically ventilated patients.

METHODS

Patients receiving mechanical ventilation for ≥48 h and reporting dyspnoea (unidimensional dyspnoea visual analogue scale (Dyspnoea-VAS)) first underwent increased pressure support and then, in random order, auditory stimulation (relaxing music versus pink noise) and air flux stimulation (facial versus lower limb). Treatment responses were assessed using Dyspnoea-VAS, the Multidimensional Dyspnea Profile and measures of the neural drive to breathe (airway occlusion pressure (P 0.1) and electromyography of inspiratory muscles).

RESULTS

We included 46 patients (tracheotomy or intubation n=37; noninvasive ventilation n=9). Increasing pressure support decreased Dyspnoea-VAS by median 40 mm (p<0.001). Exposure to music decreased Dyspnoea-VAS compared with exposure to pink noise by median 40 mm (p<0.001). Exposure to facial air flux decreased Dyspnoea-VAS compared with limb air flux by median 30 mm (p<0.001). Increasing pressure support, but not music exposure and facial air flux, reduced P 0.1 by median 3.3 cmH2O (p<0.001).

CONCLUSIONS

In mechanically ventilated patients, sensory interventions can modulate the processing of respiratory signals by the brain irrespective of the intensity of the neural drive to breathe. It should therefore be possible to alleviate dyspnoea without resorting to pharmacological interventions or having to infringe the constraints of mechanical ventilation lung protection strategies by increasing ventilatory support.

Randomized Controlled Study Evaluating Efficiency of Low Intensity Transcranial Direct Current Stimulation (tDCS) for Dyspnea Relief in Mechanically Ventilated COVID-19 Patients in ICU: The tDCS-DYSP-COVID Protocol

The severe respiratory distress syndrome linked to the new coronavirus disease (COVID-19) includes unbearable dyspneic suffering which contributes to the deterioration of the prognosis of patients in intensive care unit (ICU). Patients are put on mechanical ventilation to reduce respiratory suffering and preserve life. Despite this mechanical ventilation, most patients continue to suffer from dyspnea. Dyspnea is a major source of suffering in intensive care and one of the main factors that affect the prognosis of patients. The development of innovative methods for its management, especially non-drug management is more than necessary. In recent years, numerous studies have shown that transcranial direct current stimulation (tDCS) could modulate the perception of acute or chronic pain. In the other hand, it has been shown that the brain zones activated during pain and dyspnea are close and/or superimposed, suggesting that brain structures involved in the integration of aversive emotional component are shared by these two complex sensory experiences. Therefore, it can be hypothesized that stimulation by tDCS with regard to the areas which, in the case of pain have activated one or more of these brain structures, may also have an effect on dyspnea. In addition, our team recently demonstrated that the application of tDCS on the primary cortical motor area can modulate the excitability of the respiratory neurological pathways. Indeed, tDCS in anodal or cathodal modality reduced the excitability of the diaphragmatic cortico-spinal pathways in healthy subjects. We therefore hypothesized that tDCS could relieve dyspnea in COVID-19 patients under mechanical ventilation in ICU. This study was designed to evaluate effects of two modalities of tDCS (anodal and cathodal) vs. placebo, on the relief of dyspnea in COVID-19 patients requiring mechanical ventilation in ICU. Trial Registration: This protocol is derived from the tDCS-DYSP-REA project registered on ClinicalTrials.gov NCT03640455. It will however be registered under its own NCT number.

Altered anticipation and processing of aversive interoceptive experience among women remitted from bulimia nervosa

Bulimia nervosa (BN) is characterized by dysregulated intake of food, which may indicate homeostatic imbalance. Critically important for homeostatic regulation is interoception, or the sensing and processing of body-relevant information. A well-documented link between avoidance of unpleasant body sensations and BN symptoms suggests that aversive interoceptive experiences may be particularly relevant to BN pathophysiology. This study examined whether individuals with a history of BN show aberrant neural processing of aversive interoceptive stimuli. Using a cued inspiratory breathing load paradigm, we compared women remitted from BN (RBN; n = 24; to reduce the confounding effects of active bulimic symptoms) and control women (CW; n = 25). During breathing load anticipation, the RBN group, relative to CW, showed increased activation in mid-insula, superior frontal gyrus, putamen, dorsal anterior cingulate, posterior cingulate, and amygdala. However, over the course of the aversive experience, neural activation in RBN relative to CW showed an aberrant decline in most of these regions. Exploratory analyses indicated that greater activation during breathing load anticipation was associated with past bulimic symptom severity and the duration of symptom remission. An exaggerated anticipatory response and an abnormally decreasing response during aversive homeostatic perturbations may promote hallmark bulimic behaviors-binge eating, dietary restriction, and purging. Our findings support a role for homeostatic instability in BN, and these altered patterns of brain activation may serve as novel targets for pharmacological, neuromodulatory, and behavioral interventions.

Altered interoceptive activation before, during, and after aversive breathing load in women remitted from anorexia nervosa

BACKGROUND

The neural mechanisms of anorexia nervosa (AN), a severe and chronic psychiatric illness, are still poorly understood. Altered body state processing, or interoception, has been documented in AN, and disturbances in aversive interoception may contribute to distorted body perception, extreme dietary restriction, and anxiety. As prior data implicate a potential mismatch between interoceptive expectation and experience in AN, we examined whether AN is associated with altered brain activation before, during, and after an unpleasant interoceptive state change.

METHODS

Adult women remitted from AN (RAN; n = 17) and healthy control women (CW; n = 25) underwent functional magnetic resonance imaging during an inspiratory breathing load paradigm.

RESULTS

During stimulus anticipation, the RAN group, relative to CW, showed reduced activation in right mid-insula. In contrast, during the aversive breathing load, the RAN group showed increased activation compared with CW in striatum and cingulate and prefrontal cortices (PFC). The RAN group also showed increased activation in PFC, bilateral insula, striatum, and amygdala after stimulus offset. Time course analyses indicated that RAN responses in interoceptive processing regions during breathing load increased more steeply than those of CW. Exploratory analyses revealed that hyperactivation after breathing load was associated with markers of past AN severity.

CONCLUSIONS

Anticipatory deactivation with a subsequent exaggerated brain response during and after an aversive body state may contribute to difficulty predicting and adapting to internal state fluctuation. Because eating changes our interoceptive state, restriction may be one method of avoiding aversive, unpredictable internal change in AN.

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.

Experimental dyspnea as a stressor: differential cardiovegetative responses to inspiratory threshold loading in healthy men and women

Dyspnea is associated with an emotional reaction that involves limbic activation. The inspiratory threshold load (ITL) is known to elicit a dyspneic response in healthy subjects. Laboratory-induced stress conditions have been shown to elicit sex-related differences in cardiovascular responses. The aim of this study was to evaluate how healthy men ( n = 8) and women ( n = 9) react and adapt to 5-min periods of ITL at three levels (low, medium, and high) in terms of heart rate (HR), temporal (RMSSD) and spectral (LF, HF, LF/HF ratio) HRV indexes, and rating of breathing discomfort. HR increased with low, medium, and high ITL in men, whereas it increased only with high ITL in women. LF/HF ratio increased at low ITL in both men and women. Modifications appear to depend essentially on increased LF in men and on reduced HF in women. In addition, HRV modifications differ between men and women, following the order of presentation of ITLs. Our results show a continuous and sustained stress in men (increased HR, LF, and LF/HF ratio across ITL presentation) and a stress adaptation in women. Subjective responses of breathing discomfort were not correlated with sympatho-vagal balance modifications for a subgroup of subjects ( n = 10). Breathing against the ITL induced autonomic modifications that are different between men and women, i.e., driven by sympathetic mediated responses in men, whereas women showed a greater parasympathetic modulation of cardiovascular activity. These results highlight the role of the mechanical inspiratory load in the heart rate variability seen in chronic obstructive pulmonary disease.

NEW & NOTEWORTHY Breathing against the ITL induced autonomic modifications driven by sympathetic mediated responses in men, whereas women showed a greater parasympathetic modulation of cardiovascular activity, even for low load. A stress circuit could be at the origin of autonomic modifications induced by ITL. Our results would underline the role of the mechanic inspiratory load in the abnormalities in heart rate variability seen in COPD patients.

Management of acute breathlessness in the person with chronic refractory breathlessness

PURPOSE OF REVIEW

The purpose of this review is to synthesize the current literature on classification and management of acute breathlessness that occurs in patients who are living with chronic refractory breathlessness related to cancer, cardiopulmonary, or neuromuscular disease.

RECENT FINDINGS

In the context of chronic refractory breathlessness, acute breathlessness can be classified as either episodic breathlessness or breathlessness crisis. Episodic breathlessness is characterized by the severity, duration, and predictability of the symptom, and by the presence or absence of a trigger such as exertion, emotion, or an environmental factor. Breathlessness crisis is more sustained, occurs at rest, and overwhelms the patient's and caregivers' coping abilities, similar to the nontriggered unpredictable types of episodic breathlessness. Treatment of acute breathlessness focuses on alleviating the episode as quickly as possible without escalating medical intervention that may not be consistent with the patient's treatment preferences.

SUMMARY

Attention to breathlessness in the published literature has increased exponentially in the past two decades. The challenge is now to translate the research findings into relief of symptoms, suffering, and distress in those who suffer from acute and chronic breathlessness because of chronic illness.

Home-based respiratory rehabilitation in adult patients with moderate or severe persistent asthma

OBJECTIVE

We assessed retrospectively the feasibility of a home-based respiratory rehabilitation (RR) program for asthmatics under optimal pharmacological treatment, as this type of care can reduce costs and offer a more patient-friendly approach for subjects with persistent asthma.

METHODS

Fifty-two patients with persistent asthma were recruited to the RR program (20 males, 32 females, 54 ± 11 (SD) years, forced expiratory volume in one second 71 ± 33% of predicted mean value, BMI 29.9 ± 7.9 kg/m(2)). This two-month protocol comprised education sessions, respiratory physiotherapy and an exercise training program at home and in groups supervised by an adapted physical activity instructor.

RESULTS

Thirty-nine patients completed the whole RR program, i.e. 25% dropout. The dropout rate was significantly higher with respect to younger patients in employment. The number of exacerbations decreased significantly during the year following the program, regardless of whether the patients had dropped out (p < 0.02) or not (p < 0.001). The distance walked during a 6-min walking test increased by 33 m (p < 0.001). Several indices measured during a cycle ergometer test increased significantly after RR: peak oxygen uptake (10%), oxygen uptake at ventilatory threshold (12%) and maximum load (19%), all at a similar maximum heart rate. Concerning quality of life assessment, the Short-Form-36 Item Health Survey revealed a non-significant improvement in the "health change" item after RR (p < 0.07).

CONCLUSIONS

This study demonstrates the potential of a home-based program in the treatment and rehabilitation of patients with asthma. Both functional and physiologic indices improved during the follow-up period.

Sex differences in the neural processing of aversive interoceptive events: the benefit of relief

Do men and women process and experience unpleasant bodily states differently? We used fMRI to determine brain processing before, during and after an aversive respiratory stimulation. No sex difference emerged during anticipation or stimulation. However, after the offset of the stimulation, men but not women showed enhanced activation of brain regions that are important for interoception and reward processing. Moreover, this activation was highest in those males who rated the preceding stimulation as most unpleasant. These results indicate that men are particularly sensitive to reward associated with the termination of an aversive event, which may signal relief.

Lung/chest expansion contributes to generation of pleasantness associated with dyspnoea relief

Pleasantness associated with dyspnoea relief or 'respiratory pleasure' is considered as a particular sensory experience. The purpose of this study is to elucidate the mechanism of generation of this particular sensory experience. After taking deep breaths during normal breathing, 35 healthy subjects received three different magnitudes of inspiratory loads (light: 8.4; moderate: 23.4; severe: 70.5 cm H2O/L/s) to induce dyspnoeic sensation. We found that (1) deep breaths during normal breathing rarely induce 'respiratory pleasure', (2) a sudden removal of dyspnoea alone is not sufficient to produce 'respiratory pleasure', and (3) the generation of 'respiratory pleasure' can be observed when a sudden removal of dyspnoea accompanies a large increase in tidal volume (V(T)). In addition, qualitative assessment of 'respiratory pleasure' showed that this sensation is compatible with a strong, positively valenced sensation. These findings indicate that an increase in V(T) after removal of respiratory loading plays a crucial role in generation of 'respiratory pleasure' that is a specific sensory-emotional experience.