Perception of intrinsic and extrinsic respiratory loads in children with life-threatening asthma

Issues affecting young people with asthma through the transition period to adult care

Asthma is among the most common medical conditions affecting children and young people, with adolescence a recognised period of increased risk, overrepresented in analyses examining recent increasing asthma mortality rates. Asthma may change significantly during this period and management also occurs in the context of patients seeking increased autonomy and self-governance whilst navigating increasing academic and social demands. A number of disease factors can destabilise asthma during adolescence including: increased rates of anaphylaxis, anxiety, depression, obesity, and, in females, an emerging resistance to corticosteroids and the pro-inflammatory effects of oestrogen. Patient factors such as smoking, vaping, poor symptom recognition, treatment non-adherence and variable engagement with health services contribute to difficult to treat asthma. Significant deficiencies in the current approach to transition have been identified by a recent EAACI task force, and subsequent asthma-specific recommendations, published in 2020 provide an important framework moving forward. As with other chronic conditions, effective transition programmes plan ahead, engage with adolescents and their families to identify the patients' management priorities and the current challenges they are experiencing with treatment. Transition needs may vary significantly across asthma patients and for more complex asthma may include dedicated transition clinics involving multidisciplinary care requiring input including, amongst others, allergy and immunology, psychological medicine, respiratory physicians and scientists and nurse specialists. Across different global regions, barriers to treatment may vary but need to be elicited and an individualised approach taken to optimising asthma care which is sustainable within the local adult healthcare system.

Dyspnea

The clinical term dyspnea (a.k.a. breathlessness or shortness of breath) encompasses at least three qualitatively distinct sensations that warn of threats to breathing: air hunger, effort to breathe, and chest tightness. Air hunger is a primal homeostatic warning signal of insufficient alveolar ventilation that can produce fear and anxiety and severely impacts the lives of patients with cardiopulmonary, neuromuscular, psychological, and end-stage disease. The sense of effort to breathe informs of increased respiratory muscle activity and warns of potential impediments to breathing. Most frequently associated with bronchoconstriction, chest tightness may warn of airway inflammation and constriction through activation of airway sensory nerves. This chapter reviews human and functional brain imaging studies with comparison to pertinent neurorespiratory studies in animals to propose the interoceptive networks underlying each sensation. The neural origins of their distinct sensory and affective dimensions are discussed, and areas for future research are proposed. Despite dyspnea's clinical prevalence and impact, management of dyspnea languishes decades behind the treatment of pain. The neurophysiological bases of current therapeutic approaches are reviewed; however, a better understanding of the neural mechanisms of dyspnea may lead to development of novel therapies and improved patient care.

Exertional Dyspnea in Childhood: Is There an Iceberg Beneath the Apex?

This essay expounds on fundamental, quantitative elements of the exercise ventilation in children, which was the subject of the Tom Rowland Lecture given at the NASPEM 2018 Conference. Our knowledge about how much ventilation rises during aerobic exercise is reasonably solid; our understanding of its governance is a work in progress, but our grasp of dyspnea and ventilatory limitation in children (if it occurs) remains embryonic. This manuscript summarizes ventilatory mechanics during dynamic exercise, then proceeds to outline our current understanding of mechanisms of dyspnea, particularly during exercise (exertional dyspnea). Most research in this field has been done in adults, and the vast majority of these studies in patients with chronic obstructive pulmonary disease. To what extent conclusions drawn from this literature apply to children and adolescents-both healthy and those with cardiopulmonary disease-will be discussed. The few, recent, pertinent, pediatric studies will be reviewed in an attempt to provide an empirical basis for proposing a hypothetical model to study exertional dyspnea in youth. Just as somatic growth will have consequences for ventilatory and exercise capacity, so too will neural developmental plasticity and experience affect perception of dyspnea. Our path to understand how these evolving inputs and influences summate during a child's life will be Columbus' India.

The Perception of Asthma Severity in Children

The ability to perceive the onset and severity of symptoms of worsening asthma is important, not only for initial diagnosis but also for early identification of an asthma exacerbation and prompt management. There are subjective and objective methods for identifying symptoms. Symptom perception is affected by multiple mechanisms, and not all patients can accurately perceive symptoms of airflow limitation. Hyperperceivers will report substantial discomfort in the face of minimal bronchoconstriction, and poor perceivers will report no symptoms even in the presence of severe obstruction. The use of objective measures of airflow limitation is essential for such patients. Regimens for training perception in children and adults have been studied and are available.

Respiratory load perception in overweight and asthmatic children

Overweight asthmatic children report greater symptoms than normal weight asthmatics, despite comparable airflow obstruction. This has been widely assumed to be due to heightened perception of respiratory effort. Three groups of children (healthy weight controls, healthy weight asthmatics, overweight asthmatics) rated perceived respiratory effort throughout an inspiratory resistive loading protocol. Parasternal intercostal electromyogram was used as an objective marker of respiratory load; this was expressed relative to tidal volume and reported as a ratio of the baseline value (neuroventilatory activity ratio (NVEAR)). Significant increases in perception scores (p<0.0001), and decreases in NVEAR (p<0.0001) were observed from lowest to highest resistive load. Higher BMI increased overall perception scores, with no influence of asthma or BMI-for-age percentile on the resistance-perception relationships. These data, indicating elevated overall respiratory effort in overweight asthmatic children but comparable responses to dynamic changes in load, suggest that the greater disease burden in overweight asthmatic children may be due to altered respiratory mechanics associated with increased body mass.

On the Origin of Interoception

Over the course of a century, the meaning of interoception has changed from the restrictive to the inclusive. In its inclusive sense, it bears relevance to every individual via its link to emotion, decision making, time-perception, health, pain, and various other areas of life. While the label for the perception of the body state changes over time, the need for an overarching concept remains. Many aspects can make any particular interoceptive sensation unique and distinct from any other interoceptive sensation. This can range from the sense of agency, to the physical cause of a sensation, the ontogenetic origin, the efferent innervation, and afferent pathways of the tissue involved amongst others. In its overarching meaning, interoception primarily is a product of the central nervous system, a construct based on an integration of various sources, not per se including afferent information. This paper proposes a definition of interoception as based on subjective experience, and pleas for the use of specific vocabulary in addressing the many aspects that contribute to it.

Reliability and predictors of resistive load detection in children with persistent asthma: a multivariate approach

OBJECTIVE

Resistive load detection tasks enable analysis of individual differences in psychophysical outcomes. The purpose of this study was to determine both the reliability and predictors of resistive load detection in children with persistent asthma who completed multiple testing sessions.

METHODS

Both University of North Carolina (UNC) Charlotte and Ohio University institutional review boards approved the research protocol. The detection of inspiratory resistive loads was evaluated in 75 children with asthma between 8 and 15 years of age. Each child participated in four experimental sessions that occurred approximately once every 2 weeks. Multivariate analyses were used to delineate predictors of task performance.

RESULTS

Reliability of resistive load detection was determined for each child, and predictors of load detection outcomes were investigated in two groups of children: those who performed reliably in all four sessions (n = 31) and those who performed reliably in three or fewer sessions (n = 44). Three factors (development, symptoms, and compliance) accounted for 66.3% of the variance among variables that predicted 38.7% of the variance in load detection outcomes (Multiple R = 0.62, p = 0.004) and correctly classified performance as reliable or less reliable in 80.6% of the children, χ(2)(12) = 28.88, p = 0.004.

CONCLUSIONS

Cognitive and physical development, appraisal of symptom experiences, and adherence-related behaviors (1) account for a significant proportion of the interrelationships among variables that affect perception of airflow obstruction in children with asthma and (2) differentiate between children who perform more or less reliably in a resistive load detection task.

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.

Effects of feedback on the perception of inspiratory resistance in children with persistent asthma: a signal detection approach

OBJECTIVE

Accurate perception of asthma episodes increases the likelihood that they will be managed effectively. The purpose of the study was to examine the effect of feedback in a signal detection task on perception of increased airflow obstruction in children with persistent asthma.

METHODS

The effect of feedback training on the perception of resistive loads was evaluated in 155 children with persistent asthma between 8 and 15 years of age. Each child participated in four experimental sessions that occurred approximately once every 2 weeks, an initial session followed by three training sessions. During the initial session, the threshold resistance to breathing was determined for each child. Subsequently, each child was randomly assigned to one of two resistive load training conditions in a signal detection paradigm: training with immediate performance feedback or training with no performance feedback.

RESULTS

The threshold resistance to breathing, determined in the initial session, was equivalent between groups. Children in the feedback condition discriminated more accurately between both the presence and the absence of increases in the resistance to breathing (206 [48] versus 180 [39] correct responses, p < .001), and differences over time between groups increased reliably as a function of training (165 [40] versus 145 [32] correct responses, p < .001). Response times and confidence ratings were equivalent between groups, and no differences in breathing patterns were observed between conditions.

CONCLUSIONS

Feedback training results in improved perception of respiratory sensations in children with asthma, a finding with implications for strategies of asthma self-management.

Perception of bronchoconstriction: a complementary disease marker in children with asthma

INTRODUCTION

Asthma guidelines use symptoms as the most important aspect of asthma control. Symptom perception varies widely between individuals. Over-perception as well as underperception of bronchoconstriction could have a negative effect on asthma management. We hypothesized that perception of bronchoconstriction in childhood asthma is not related to common measures of disease control. For that reason, we examined the clinical determinants of the perception of bronchoconstriction and the repeatability of perception measurements.

PATIENTS AND METHODS

In school-age children with moderately severe atopic asthma, we measured the perception of bronchoconstriction (decrease in forced expiratory volume in 1 second (FEV(1)) during methacholine bronchoprovocation challenges. The perception of bronchoconstriction was assessed as the slope of the relation between FEV(1) and Borg score, and as the Borg score at a 20% decrease in FEV(1) from baseline during the provocation test (PS(20)). Data from subjects who had a 20% or more decrease in FEV(1) (n = 112) were used for the analysis. Fifty-four children repeated the test after 3 months. Symptoms, use of rescue medication, and peak expiratory flows were scored in diaries during the 2 weeks before testing.

RESULTS

Symptom perception was significantly better in children without (PD(20) > 1570 μg, n = 28) than in children with airway hyperresponsiveness (PD(20) ≤ 1570 μg, n = 112), slope 0.22 versus 0.13 respectively (p < .001). Borg scores correlated with PD(20) (p = .01), baseline FEV(1) (only for slope, p = .04), and use of rescue beta agonist (p = .01), but not with other aspects of asthma control. Repeatability of Borg scores was good (slope: R = 0.59, PS(20): R = 0.52).

CONCLUSION

Poorer symptom perception in asthmatic children correlated with hyperresponsiveness, and was associated with lower baseline FEV(1) and less use of rescue bronchodilators. This suggests that the measurement of symptom perception should be taken into account in individual management plans for children with asthma.

The impact of emotion on the perception of graded magnitudes of respiratory resistive loads

Emotional state can modulate the perception of respiratory loads but the range of respiratory load magnitudes affected by emotional state is unknown. We hypothesized that viewing pleasant, neutral and unpleasant affective pictures would modulate the perception of respiratory loads of different load magnitudes. Twenty-four healthy adults participated in the study. Five inspiratory resistive loads of increasing magnitude (5, 10, 15, 20, 45 cm H(2)O/L/s) were repeatedly presented for one inspiration while participants viewed pleasant, neutral and unpleasant affective picture series. Participants rated how difficult it was to breathe against the load immediately after each presentation. Only at the lowest load, magnitude estimation ratings were greater when subjects viewed the unpleasant series compared to the neutral and pleasant series. These results suggest that negative emotional state increases the sense of respiratory effort for single presentations of a low magnitude resistive load but high magnitude loads are not further modulated by emotional state.

Relationship between Respiratory Load Perception and Perception of Nonrespiratory Sensory Modalities in Subjects with Life-Threatening Asthma

Subjects with life-threatening asthma (LTA) have reported decreased sensitivity to inspiratory resistive (R) loads. It is unknown if decreased sensitivity is specific for inspiratory R loads, other types of respiratory loads, or a general deficit affecting sensory modalities. This study hypothesized that impairment is specific to respiratory stimuli. This study tested perceptual sensitivity of LTA, asthmatic (A), and nonasthmatic (NA) subjects to 4 sensory modalities: respiratory, somatosensory, auditory, visual. Perceptual sensitivity was measured with magnitude estimation (ME): respiratory loads ME, determined using inspiratory R and pressure threshold (PT) loads; somatosensory ME, determined using weight ranges of 2–20 kg; auditory ME, determined using graded magnitudes of 1 kHz tones delivered for 3 seconds bilaterally; visual ME, determined using gray-to-white disk intensity gradations on black background. ME for inspiratory R loads lessened for LTA over A and NA subjects. There was no significant difference between the 3 groups in ME for PT inspiratory loads, weight, sound, and visual trials. These results demonstrate that LTA subjects are poor perceivers of inspiratory R loads. This deficit in respiratory perception is specific to inspiratory R loads and is not due to perceptual deficits in other types of inspiratory loads, somatosensory, auditory, or visual sensory modalities.

Beyond the guidelines: fatal and near-fatal asthma

While asthma is extremely common, fatal and near fatal asthma is rare and often preventable if there is early recognition of symptom progression and appropriate intervention. In the past decade, asthma mortality has progressively declined in association with the widespread use of inhaled corticosteroids and asthma care plans. Management of life threatening asthma requires patient education to ensure the proper use of medications and to enable the patient to recognize when additional therapy for poorly controlled asthma is required. There is some evidence that suggests that the overly aggressive use of asthma medications when treating a severe exacerbation may contribute to morbidity. Because of the risks of air trapping and barotrauma associated with partial airway obstruction, it is best to avoid mechanical ventilation if possible but when this is used, low tidal volumes, longer exhalation times, and permissive hypercarbia can minimize these risks. There is the promise that a better understanding of asthma immunology and severe asthma "phenotypes" will lead to better prevention and therapy.

Perception of multiple-breath inspiratory resistive loads in males and females

Resistive load magnitude estimation (ME) was measured over multiple breaths in male and female subjects. It was hypothesized that multiple breaths against a range of resistive loads would result in a change in the perceived load magnitude as a function of load magnitude and the number of inspiratory efforts. It was further hypothesized that males and females would differ in their perceptual response to sustained breathing against inspiratory resistive loads. The subjects were tested in a sound isolated room and respired through a non-rebreathing valve, the inspiratory port connected to the loading manifold. The subject inspired to a peak airflow target for each breath. Each R load was presented for 10 continuous breaths. The load was estimated at breath 1, 5, and 10 using a modified Borg scale. Each 10-breath load presentation was presented in a randomized block. There was no significant group difference between the ME for breath 1 and 10 for small R loads, but a significant group difference for large R loads. The ME for males did not change between breath 1 and 10 for the small load magnitudes, but decreased with large loads. The ME for the 10th breath of the large R load was greater than the 1st breath for females. Males estimated the large R load on the 1st breath the same as females but the ME on the 10th breath was significantly less for males compared to females. These results demonstrate that magnitude estimation of large resistive loads with a sustained 10-breath trial elicits significant increases in females, but significantly decreased in males. The increase in ME may represent increased respiratory discomfort for females and the decrease habituation in males.

Do asthma patients prefer to monitor symptoms or peak flow?

We administered a 65-item survey to patients to assess preference of symptoms and peak flow to detect worsening asthma and to collect information about asthma triggers, asthma knowledge sources, and barriers to peak flow meter use. It was completed by 139 asthma patients. Survey responses were comparable for adult and pediatric patients and for those who owned peak flow meters and those who did not. But patients who owned a peak flow meter reported more severe asthma than others. On average, the patients preferred symptoms to peak flow for assessing worsening asthma. It is likely that the preference for symptom over peak flow monitoring was effort related: Patients preferred symptom monitoring because it was the easier of the two to conduct.

Perception of dyspnea during acetylcholine-induced bronchoconstriction in asthmatic children

BACKGROUND

Few studies have examined the relationship between dyspnea perception and bronchial hyperresponsiveness (BHR) in asthmatic children.

OBJECTIVE

To test the hypothesis that severe BHR is associated with poor perception of the severity of airway obstruction.

METHODS

One hundred one asthmatic children (mean [SD] age, 11.1 [2.3] years) were evaluated using acetylcholine chloride (Ach) challenge. The BHR was assessed as the provocative concentration of Ach causing a 20% decrease in forced expiratory volume in 1 second (FEV1) (PC20). Perception of dyspnea was scored using a modified Borg scale after each dose of Ach and bronchodilator. The dyspnea threshold was defined as the point at which the Borg scale score became higher than 0. We evaluated the dyspnea perception score at a 20% decrease in FEV1 relative to baseline (PS20) and after bronchodilator administration (PS(BD)).

RESULTS

The mean (SD) PS20 and PS(BD) were significantly lower in the severe vs the mild BHR group (PS20: 2.1 [1.9] vs 4.2 [2.4], P < .001; PS(BD): 0.5 [1.0] vs 1.0 [1.3], P = .048). The mean (SD) % decrease in FEV1 at the dyspnea threshold was significantly greater in the severe vs the mild BHR group (14.1% [11%] vs 5.4% [11%], P < .001). The PS20 was correlated positively with the PC20 (r2 = 0.25, P < .001), and the decrease in FEV1 at the dyspnea threshold was correlated negatively with the PC20 (r2 = 0.18, P < .001).

CONCLUSIONS

Moderate to severe asthmatic children with severe BHR perceive dyspnea only after the stage of mild bronchoconstriction has passed. This relative insensitivity to dyspnea in asthmatic children with severe BHR may lead to undertreatment of asthma.

Inaccurate perception of asthma symptoms: a cognitive-affective framework and implications for asthma treatment

Inaccurate perception of respiratory symptoms is often found in asthma patients. Typically, patients who inaccurately perceive asthma symptoms are divided into underperceivers and overperceivers. In this paper we point out that this division is problematic. We argue that little evidence exists for a trait-like stability of under- and overperception and that accuracy of respiratory symptom perception is highly variable within persons and strongly influenced by contextual information. Particularly, expectancy and affective cues appear to have a powerful influence on symptom accuracy. Based on these findings and incorporating recent work on associative learning, attention and mental representations in anxiety and symptom perception, we propose a cognitive-affective model of symptom perception in asthma. The model can act as a framework to understand both normal perception as well as under- and overperception of asthma symptoms and can guide the development of affect-related interventions to improve perceptual accuracy, asthma control and quality of life in asthma patients.

The multiple dimensions of dyspnea: review and hypotheses

Although dyspnea is a common and troubling symptom, our understanding of the neurophysiology of dyspnea is woefully incomplete. Most measurements of dyspnea treat it as a single entity. Although the multidimensional dyspnea concept has been mentioned for many decades, only recently has the concept been the subject of experimental tests. Emerging evidence has begun to favor the hypothesis that dyspnea comprises multiple dimensions or components that can be measured as different entities. Most recently, studies have begun to show that there is a separable 'affective dimension' (i.e. unpleasantness and emotional impact). Understanding of the multidimensional measurement of pain is far in advance of dyspnea, and has enabled progress in the neurophysiology of pain, including identification of separate neural structures subserving various elements of pain perception. We propose here a multidimensional model of dyspnea based on a state-of-the-art pain model, and review existing evidence in the light of this model.

Perception of Inspiratory Resistive Loads in Asthmatic Children with Attention Deficit Disorder

Magnitude estimation (ME) of inspiratory resistive (R) loads has been studied in asthmatic children. Some children have been reported to be unable to perform the perception task. One reason some children may be unable to perform the ME task is Attention Deficit Disorder (ADD) or Attention Deficit Hyperactivity Disorder (ADHD). The aim of this study was to determine if asthmatic patients with ADD/ADHD have a perceptual and/or attention deficit in the ME of graded inspiratory R loads.

Methods

Asthmatic children aged 11-18 years were classified into ADD/ADHD and asthma control groups. Perception of extrinsic loads was assessed by handgrip ME of inspiratory R loads. A methacholine challenge was performed and the PC20 for each subject determined.

Results

There was no significant difference between asthma control and ADD/ADHD groups in the group mean for the slope of ME-R load slopes. The ADD/ADHD subjects had significantly greater variability in ME of R loads.

Conclusions

Asthmatic children with ADD/ADHD do not have an impaired perception of extrinsic respiratory loads but do have difficulty attending to the perceptual task. Difficulties in their asthma management may be due to their attention deficit and not their symptom perception.

Symptom perception in pediatric asthma: resistive loading and in vivo assessment compared

BACKGROUND

Inaccurate symptom perception contributes to asthma morbidity and mortality in children and adults. Various methods have been used to quantify perceptual accuracy, including psychophysical (resistive loading) approaches, ratings of dyspnea during induced bronchoconstriction, and in vivo monitoring, but it is unclear whether the different methods identify the same individuals as good or poor perceivers. The objectives of the study were as follows: (1) to compare in the same asthmatic children two methods of quantifying perceptual ability: threshold detection of added resistive loads and in vivo symptom perception; and (2) to determine which method best predicts asthma morbidity.

METHODS

Seventy-eight asthmatic children 7 to 16 years of age completed two threshold detection protocols in the laboratory and recorded their subjective estimates of lung function prior to spirometry at home twice daily for 5 to 6 weeks. Summary measures from both methods were compared to each other and to asthma morbidity (as measured with the Rosier asthma functional severity scale).

RESULTS

Symptom perception ability, as summarized by either method, varied greatly from child to child. Neither of the resistive load detection thresholds were significantly related to any of the three in vivo perception scores, nor were they related to asthma morbidity. The three in vivo scores did show a significant or marginal relationship with morbidity (p < 0.01, p < 0.06, and p < 0.07, respectively).

CONCLUSIONS

Resistive loading techniques may not be useful in assessing symptom perception ability in children. Measuring estimates of symptoms in relation to naturally occurring asthma can identify children at risk for greater asthma morbidity.

Symptom perception and functional morbidity across a 1-year follow-up in pediatric asthma

The purpose of this study was to examine the association between asthma symptom perception measured during a 5-6 week baseline and functional morbidity measured prospectively across a 1-year follow-up. Symptom perception was measured by comparing subjective ratings with peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV(1)). We hypothesized that accurate symptom perception (ASP) would be associated with less functional morbidity. Participants consisted of 198 children with asthma ages 7-17 recruited from three sites. The children used a programmable electronic spirometer in the home setting to guess their PEFR prior to exhalation. Each "subjective" guess was classified as being in an ASP, dangerous symptom perception (DSP; underestimation of symptoms), or symptom magnification (SM; overestimation) zone based upon the corresponding measurement of PEFR or FEV(1). An index of functional morbidity was collected by parent report at baseline and across 1-year follow-up. A greater proportion of ASP blows and a lower proportion of DSP blows based on PEFR predicted less functional morbidity reported at baseline, independent of asthma severity and race/ethnicity. A greater proportion of ASP blows (using PEFR and FEV(1)) and a lower proportion of SM blows (using FEV(1)) predicted less functional morbidity across 1-year follow-up. Symptom perception was not associated with emergency department visits for asthma at baseline or across follow-up. In comparison to PEFR, FEV(1) more frequently detected a decline in pulmonary function that children did not report. Symptom perception measured in naturalistic settings was associated with functional morbidity at baseline and prospectively across 1-year follow-up. Support was found for including multiple measures of pulmonary function in the assessment of asthma symptom perception.

The impact of emotions on the perception of dyspnea in pediatric asthma

Inadequate symptom perception is increasingly recognized as a contributing factor in asthma morbidity. Recent research has shown that psychological factors can influence the perception of asthmatic symptoms such as dyspnea, but little is known, about the impact of emotions on the perception of dyspnea in pediatric asthma. Therefore, we examined the impact of viewing affective film clips of positive, neutral, and negative valence on perceived dyspnea during resistive load breathing in children with stable mild asthma. Perceived dyspnea decreased during the positive film compared to baseline and neutral film whereas the level of respiratory loading and respiratory resistance (R5) remained unchanged across conditions. The results underline the potential impact of psychological factors such as emotions on the perception of dyspnea in children with asthma.

Symptom perception and adherence to asthma controller medications

PURPOSE

To explore asthma symptom perception and the relationship between asthma symptom perception and adherence to asthma treatment.

DESIGN

Adult patients (N=120) of asthma/allergy specialty clinics, taking Advair as a controller medication, were enrolled in this cross-sectional descriptive study.

METHODS

Ninety-seven participants completed 4 weeks of daily diaries to assess subjective symptom perception and measured peak expiratory flow rates (PEFR), both done twice daily. Individual perceptual accuracy scores (PAS) were determined by correlating the subjective symptom perception scores with the PEFRs. Measures included demographic variables, illness identity (personal control and treatment control, consequences, and timeline-cyclical subscales of the IPQ-R), asthma severity (FEV1 percentage) and a single-item indicator of perceived asthma severity. Adherence was measured by the Medication Adherence Report Scale (MARS) and by an Advair dose count (percentage of doses taken as prescribed).

FINDINGS

Independent t tests comparing adherence rates of good versus poor perceivers were not significant, using either the percentage Advair dose count or the MARS. Multiple regression analyses showed that years with asthma, illness identity, and peak flow variability were all significant explanatory variables for perceptual accuracy.

CONCLUSION

Peak flow variability adds complexity to the relationship between perceptual accuracy and adherence that warrants further investigation.

Symptom perception in childhood asthma: the role of anxiety and asthma severity

This study tested the relationship of anxiety and asthma severity to symptom perception. Eighty-six children diagnosed with mild or moderate asthma had symptom perception and pulmonary function measured throughout methacholine challenge (to induce bronchoconstriction). Higher trait anxiety was associated with heightened symptom perception (controlling for pulmonary function) at baseline. Greater asthma severity was associated with blunted symptom perception (controlling for pulmonary function) at the end of methacholine challenge and with a slower rate of increase in symptom perception across methacholine challenge. These results suggest that anxiety plays a role when children's symptoms are mild, whereas medical variables such as severity play a role in perception of changes in asthma symptomatology as bronchoconstriction worsens.

Advancing the science of perceptual accuracy in pediatric asthma and diabetes

OBJECTIVES

To review research on perceptual accuracy in pediatric asthma and diabetes and to provide recommendations for future research efforts and clinical applications of the construct in these populations.

METHODS

A literature search was conducted using Medline and PsychInfo databases as well as the bibliographies of relevant articles.

RESULTS

Children and adolescents with asthma or diabetes evidence considerable variability in perceptual accuracy and frequently make clinically relevant errors that have the potential to affect self-management behavior.

CONCLUSIONS

Recommendations for future research include studying distinct types of perceptual errors, empirically supporting the relationship between perceptual accuracy and relevant outcomes, identifying factors related to perceptual inaccuracy, and conducting longitudinal research and intervention studies. Recommendations for applying the construct in clinical practice include adopting an individualized approach to symptoms to guide patient education and management, identifying patients prone to making clinically relevant errors, and developing and implementing interventions to improve accuracy.