Dyspnoea in children. Does development alter the perception of breathlessness?

The role of cardiopulmonary exercise testing in evaluating children with exercise induced dyspnoea

Exercise induced dyspnoea (EID) is a common manifestation in children and adolescents. Although EID is commonly attributed to exercise induced bronchoconstriction, several conditions other than asthma can cause EID in otherwise healthy children and adolescents. Cardiopulmonary exercise testing (CPET) offers a non-invasive comprehensive assessment of the cardiovascular, ventilatory and metabolic responses to exercise and is a powerful diagnostic and prognostic tool. CPET is a reproducible, non-invasive form of testing that allows for comparison against age- and gender-specific norms. CPET can assess the child's exercise capacity, determine the limiting factors associated with this, and be used to prescribe individualised interventions. EID can occur due to asthma, exercise induced laryngeal obstruction, breathing pattern disorders, chest wall restriction and cardiovascular pathology among other causes. Differentiating between these varied causes is important if effective therapy is to be initiated and quality of life improved in subjects with EID.

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.

Difficult vs. Severe Asthma: Definition and Limits of Asthma Control in the Pediatric Population

Evaluating the degree of disease control is pivotal when assessing a patient with asthma. Asthma control is defined as the degree to which manifestations of the disease are reduced or removed by therapy. Two domains of asthma control are identified in the guidelines: symptom control and future risk of poor asthma outcomes, including asthma attacks, accelerated decline in lung function, or treatment-related side effects. Over the past decade, the definition and the tools of asthma control have been substantially implemented so that the majority of children with asthma have their disease well controlled with standard therapies. However, a small subset of asthmatic children still requires maximal therapy to achieve or maintain symptom control and experience considerable morbidity. Childhood uncontrolled asthma is a heterogeneous group and represents a clinical and therapeutic challenge requiring a multidisciplinary systematic assessment. The identification of the factors that may contribute to the gain or loss of control in asthma is essential in differentiating children with difficult-to-treat asthma from those with severe asthma that is resistant to traditional therapies. The aim of this review is to focus on current concept of asthma control, describing monitoring tools currently used to assess asthma control in clinical practice and research, and evaluating comorbidities and modifiable and non-modifiable factors associated with uncontrolled asthma in children, with particular reference to severe asthma.

Dyspnea in Children: What is driving it and how to approach it

Dyspnea in children has important physical and psychosocial impact. It is useful to define the quality of the dyspnea and quantify its magnitude in a child-friendly manner. Through careful history taking and physical examination, a targeted investigation can lead to identification of the cause and potential treatment. This article provides a framework for the clinical approach to dyspnea in children, including important information to gather during the history, physical assessment, how to quantify dyspnea, and choice and use of laboratory measurements.

Down-Regulation of Cough during Exercise Is Less Frequent in Healthy Children than Adults. Role of the Development and/or Atopy?

Cough is typically associated with physical activity in children with asthma, but the characteristics of the relationship between cough and exercise has not been established under physiological conditions. The aim of the study was to describe the effect of exercise on the reflex cough response elicited by a single breath of capsaicin in non-asthmatic children. A group of non-asthmatic adults was studied as reference. Thirty children and 29 adults were recruited. The cough reflex sensitivity to capsaicin was first determined to establish the dose that provokes 5 cough efforts (C5). The number of coughs elicited by C5 (NC5) was then compared at baseline and during a standardized submaximal treadmill exercise. Data are expressed as median (interquartile range). Children and adults showed a significant decrease in NC5 (respectively from 5.0 (4.0–6.0) to 2.5 (2.0–4.0), p < 0.0005 and from 6.0 (5.0–7.0) to 2.0 (0.0–3.0, p < 0.0005). During exercise, NC5 was observed to decrease in all adult subjects, but in only 24/30 children (80%, p = 0.02). A trend for a higher incidence of personal and familial atopy was observed in children that lacked cough down-regulation during exercise compared with other children. It is concluded that the cough reflex response to capsaicin is down regulated by exercise in both children and adults. The effect however is less consistently observed in the former. The difference may reflect maturation of descending inhibitory pathways of the cough reflex, but may also be associated to atopy. The data stress the importance of assessing the time relationship of cough and exercise in questionnaire studies of asthma.

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.

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.

Dalhousie Dyspnea and perceived exertion scales: psychophysical properties in children and adolescents

Children and adolescents vary widely in their perception of, or capacity to rate, sensations during exercise using the Borg scale. We sought to measure sensory-perceptual responses obtained using Dalhousie Dyspnea and Perceived Exertion Scales in 79 pediatric subjects during maximal exercise challenge and to determine the psychophysical function relationship(s). Concurrent validity was assessed by canonical plots of mean ratings on either scale, which showed showing very good correlations for perceived leg exertion vs work, and dyspnea vs ventilation. Both scales yielded similar results with respect to goodness of fit regardless of whether data was fitted to a power or quadratic function provided a delay term was included. The quadratic model fixed the exponent of the power law at 2 but, unlike a power model, allowed characterization of individual responses that increased and then plateaued. Dalhousie Dyspnea and Perceived Exertion Scales offer an alternative to Borg scale during exercise in pediatric populations.

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.

Exercise-induced bronchoconstriction in school-age children born extremely preterm

BACKGROUND

School children born preterm often show airway hyperresponsiveness to methacholine or histamine. Less attention has been paid to their airway response to exercise, an important point because of the role of exercise in the child's daily life. The aim of this study was to describe the characteristics of, and potential determinants to, the airway response to exercise in children born extremely preterm.

METHODS

Forty-two nonasthmatic nonatopic children born before 32 wk gestation were compared with 27 healthy nonasthmatic nonatopic term children at age 7. Spirometry and respiratory impedance were measured at baseline and repeated after a single-step 6-min treadmill exercise in a climate-controlled room.

RESULTS

The preterm group showed significant broncho-constriction induced by exercise. Prematurity, but not low baseline lung function, neonatal oxygen supplementation, mechanical ventilation, chronic lung disease, or maternal smoking, was a determinant of exercise-induced bronchoconstriction.

CONCLUSION

Children born extremely preterm present significant exercise-induced airway obstruction at age 7. The response has different characteristics from that occurring in asthmatics and is likely to express airway noneosinophilic inflammation.

Pulmonary neuroepithelial bodies as airway sensors: putative role in the generation of dyspnea

The neuroepithelial bodies (NEB) of the intrapulmonary airways (AW) are multimodal AW sensors responding to a variety of stimuli including hypoxia, hypercarbia, and mechanical stretch. NEBs are richly innervated by a diverse population of mostly vagal afferent nerve fibers and owing to their early developmental maturation may be especially important during the perinatal period. This article reviews recent findings of NEB functional morphology and innervation, and postulates a role in the generation of dyspnea. This is based on their potential for transduction of dyspneic stimuli and findings of NEB cell abnormalities in a number of pulmonary disorders presenting with this symptom.

[Problems for assessing the newborns' pain in palliative care]

Several pain scales are available for newborns, but the assessment of pain in these preverbal beings, who are in continuing neurological development, remains challenging for healthcare teams. Although neonates at the end of life are particularly vulnerable to pain and discomfort, no assessment tool has been validated in this specific population. The difficulties for assessing pain in this context are copies of those potentially encountered in other situations. Questions arise about the limits of the available scales, about possible alterations of responses to a noxious stimulus in particular contexts (extreme immaturity, brain lesions), about possibly painful situations in palliative care, about the nature of scales to choose. Data show a perception of pain at a cortical level by extremely immature infants and the ability for neonates with significant neurological injury to express pain behaviours. For some potentially painful situations (dyspnoea, gasps, hunger) neonatal data are virtually nonexistent. Fundamental scientific data and clinical data from adults and children can give some answers. One will choose scales for which the staff is trained, easily usable (preference for behavioural scales), validated for all gestational ages, reliable in the event of neurological impairment or sedation. An assessment of prolonged pain (EDIN scale or COMFORT Behaviour scale) combined with measures of acute pain (DAN or NFCS scales) is recommended. These scales should be better validated for populations of newborns and situations that are specific to palliative care. A better assessment of the parental perception and of their distress about the discomfort or pain of their child is warranted.

Descriptors of breathlessness in children with persistent asthma

BACKGROUND

In adult patients, the consistent use of language to describe dyspnea enhances patient-provider communication and contributes to diagnostic and therapeutic decisions. The objective of this research was to determine whether pediatric patients similarly display consistency in the language used to describe "uncomfortable awareness of breathing."

METHODS

One hundred children between the ages of 8 and 15 years with moderate to severe persistent asthma enrolled in an asthma education research program completed questionnaires regarding descriptors of asthma on each of two occasions. In addition to the breathlessness questionnaires, demographic information, self-reported asthma severity, ED visits, missed school days, anthropometrics, and spirometry were obtained for each participant.

RESULTS

Children were reliable in their choice of the descriptors that they applied to their breathing discomfort across two occasions, and they selected the same descriptors that were used by adults with asthma in previous studies. Children with greater self-reported asthma severity endorsed more descriptors to characterize breathing discomfort than did children with less severe asthma, but no differences were found among children based on demographic or anthropometric variables.

CONCLUSIONS

Children with moderate to severe persistent asthma are reliable in their choice of descriptors of breathlessness. Knowledge of their experience of symptoms may be helpful clinically in the assessment and management of asthma.