Perception Of Breathlessness Research Articles

Influence of Beclomethasone and Salmeterol on the Perception of Methacholine-lnduced Bronchoconstriction

Patient evaluation of asthma severity and medication needs is mostly based on respiratory symptoms and may be influenced by changes in perception of bronchoconstriction-induced sensations. However, the influence of asthma medication on the ability to perceive symptoms is still to be documented. This study evaluated the effects of short-term and regular use of salmeterol on the perception of methacholine-induced bronchoconstriction (MIB) in subjects with mild asthma, using inhaled salbutamol on an "as required" basis (n=15), and in subjects with moderate asthma, using daily inhaled beclomethasone (mean daily dose, 640 microg; n=15) in addition to salbutamol to control their asthma. Methacholine challenges (MC) were performed at entry into the study, and then before, 1, and 12 h following inhalation of 50 microg of salmeterol or a placebo, after a 15-day baseline period; and after 4 weeks of twice daily use of those treatments. The measurements were then repeated with the alternate treatment after a 15-day washout period. Finally, a last MC was performed after another 15-day washout period. For each MC, the perception score of bronchoconstriction-associated breathlessness at 20% fall in FEV1 (PS20) was evaluated on a modified Borg scale from 0 to 10. Subjects using regular beclomethasone had a higher baseline PS20 than those using only salbutamol (means: 3.06 0.06 and 2.01+/-0.07, p=0.0001). Short- and long-term use of salmeterol did not change significantly the PS20 compared with placebo (p>0.05) in either group (with or without corticosteroid). Although there were some intraindividual variations, mean PS20 did not vary significantly throughout the study. These observations show that the perception of bronchoconstriction-associated breathlessness is not influenced by regular use of salmeterol. Patients using inhaled corticosteroids show a greater perception of MIB.

Personality profiles and breathlessness perception in outpatients with different gradings of asthma.

We studied the relationship between personality profiles, breathlessness perception and clinical and functional features in 36 outpatient asthmatics (12 females; age range: 18-52 yr). Each patient underwent psychometric evaluation with Minnesota Multiphasic Personality Inventory (MMPI). Breathlessness perception was evaluated by Borg's scale during methacholine (M) challenge, and PS20 (the perception score obtained when FEV1 fell by 20%) was recorded. Baseline FEV1 values ranged from 70.0 to 126%. PC20 M values ranged from 0.05 to 31.7 mg/ml. According to a symptoms score system (0 to 12 points), 12 asthmatics were classified as mild, 12 as moderate, and 12 as moderate/severe. We did not find any specific personality profile in asthmatic patients. Sixteen asthmatics had at least one MMPI subscale score indicative of psychological disturbances. We found a significant trend from mild to moderate and moderate/severe asthmatics (p < 0.015), when the number of asthmatics with subscale scores indicative of psychological disturbances was compared to that of asthmatics with normal scores. Moreover, we found that the asthmatics with scores indicative of hypochondriasis showed a significant trend from mild to moderate and moderate/severe asthma (p < 0.015). Furthermore, in all asthmatic patients, hypochondriasis scores were positively correlated to asthma severity score (p < 0.02). PS20 values ranged from 0.1 to 8.1. Twelve asthmatics were hypoperceivers (PS20 < or = 1) and four were hyperperceivers (PS20 > or = 5). We observed a significant trend from mild to moderate and moderate/severe asthmatics (p < 0.025) when we compared the number of hypoperceivers to that of normoperceivers. In conclusion, we found that in outpatients with different grading of asthma, severity of disease is linked to psychological disturbances and poor perception of breathlessness, additionally, hypochondriasis was related to disease severity in all patients.

Home-based, upper-arm exercise training for patients with chronic obstructive pulmonary disease

Prior studies demonstrate the ability of upper extremity training to increase arm strength and endurance when incorporated into a pulmonary rehabilitation program. However, patients with severe chronic obstructive pulmonary disease (COPD) may have transportation or mobility problems that make it difficult to travel to a rehabilitation site to obtain this training. This pilot study was designed to determine whether a home-based, upper-arm exercise program could increase arm strength and endurance, and decrease perceptions of breathlessness and fatigue during five activities of daily living. Twenty patients with severe COPD (FEV1 0.80 +/- 0.42) were randomized to an experimental (n = 10) or control group (n = 10). The experimental-group training included three upper arm exercises five times a week for 8 weeks, with training level incremented during weekly home visits. Control-group subjects were contacted weekly to equalize attention from health care providers. During the upper-extremity endurance test for number of rings moved, no significant differences between groups were seen for interaction or treatment. However, there was a significant interaction between treatment and time for perceived fatigue (p = 0.0012), with the experimental group perceiving less fatigue during upper arm work than did the control group. No change was seen in perceived breathlessness. Findings of this study suggest that a home-based, upper-arm exercise program can reduce perceptions of fatigue for patients with severe COPD during activities involving upper arm work. Testing in a larger sample is indicated to determine whether this training can also improve ability to perform unsupported arm work.

Dyspnoea: a study of measurement instruments for the assessment of dyspnoea and their application for patients with advanced cancer

Dyspnoea or breathlessness is a problem commonly encountered in the palliative care of many patients with advanced cancer, although its impact on the patient is frequently under-estimated. In advanced cancer, the aim of effective management is to minimize the patient's perception of breathlessness which, in turn, depends on reliable assessment. Most of the knowledge and experience of dyspnoea has been acquired through working with patients with chronic pulmonary disease and there is a dearth of literature relating specifically to the assessment of dyspnoea in advanced cancer. A critical analysis of available literature was undertaken and measurement instruments available for assessing breathlessness and their application to dyspnoeic patients with advanced cancer were reviewed. Dyspnoea is a complex, multidimensional sensation and its subjectivity makes it difficult to quantify. For patients with advanced cancer, dyspnoea may be one of many symptoms and measurement instruments need to take this into account. No single measurement instrument takes into account the different components of dyspnoea and as the final choice will depend on the purpose of assessment, it is likely that more than one instrument will be required.

Activation and inhibition of the endogenous opioid system in human heart failure.

In a canine model of congestive heart failure beta endorphin concentrations were high and opioid receptor antagonists exerted beneficial haemodynamic effects. In humans previous studies have suggested that opioid peptides may modify the perception of breathlessness and fatigue in heart failure. Plasma concentrations of beta endorphin were measured in patients with acute and chronic heart failure and cardiogenic shock. A subgroup of eight patients with New York Heart Association (NYHA) class III-IV heart failure was assessed for acute haemodynamic effects of naloxone, an opioid receptor antagonist. A separate group of 10 patients with class II-III heart failure, was randomised to a double blind placebo controlled study of the effects of intravenous naloxone on cardiopulmonary exercise performance. Plasma concentrations of beta endorphin were usually normal in patients with chronic heart failure and did not correlate with severity as assessed by NYHA class. In 29% of patients with acute heart failure and 71% of those with cardiogenic shock beta endorphin concentrations were high. The median concentration in the cardiogenic shock group was significantly higher than in either of the two heart failure groups and there was some evidence of a relation between beta endorphin concentrations and survival. At the doses tested, naloxone was unable to modify systemic haemodynamics, exercise performance, or symptoms in patients with chronic congestive heart failure. Circulating concentrations of beta endorphin are usually normal in patients with chronic congestive heart failure. Inhibition of the endogenous opioid system is unlikely to have therapeutic potential in heart failure.

Perception of airflow obstruction and associated breathlessness in normal and asthmatic subjects: correlation with anxiety and bronchodilator needs.

Perception of bronchoconstriction varies between individuals and its determinants remain to be identified. The perception of airflow obstruction and breathlessness during induced bronchoconstriction was studied, and the effects of anxiety, repetition of the stimulus, and bronchodilator needs on these measurements were examined in normal and asthmatic subjects. Fifteen normal (control) and 25 asthmatic subjects had two consecutive methacholine inhalation tests to induce a 20-50% fall in FEV1. Evaluation of the perceived magnitude of airflow obstruction, breathlessness, level of anxiety generated, and bronchodilator needs was obtained before each FEV1 measurement on a modified Borg scale from 0 to 10. Mean (SE) maximal fall in FEV1 in asthmatic and control subjects was of similar magnitude: test 1, 37.6 (1.4)% and 38.7 (3.1)%, and test 2, 36.0 (1.6)% and 27.7 (2.4)% respectively. There was a large interindividual variation in perception of airflow obstruction and breathlessness but, although they were well correlated in asthmatic subjects, they were perceived differently by the control subjects. Perception of airflow obstruction was greater in asthmatic subjects. The level of anxiety and the bronchodilator use were low and did not influence perception. During induced bronchoconstriction, the overall perception of airflow obstruction and breathlessness were similar among asthmatic subjects but controls showed a higher perception of airflow obstruction for any given level of breathlessness. Asthmatic subjects perceived airflow obstruction and breathlessness to a greater degree than did controls but anxiety and bronchodilator need were not correlated with respiratory sensation. The variability of bronchodilator use for similar degrees of bronchoconstriction suggests that it may be misleading to assess the severity of asthma control using only this indirect measure.

Perception of breathlessness during exercise in patients with respiratory disease

The perception of breathlessness during physical activities is a frequent and disturbing complaint for patients with chronic respiratory disease. Psychophysical principles can be applied to quantitate the severity of dyspnea during cardiopulmonary exercise testing. Power production (or work) appears to be the most appropriate stimulus for measuring the dyspnea response. The 0-10 category-ratio (CR-10) scale and the visual analog scale (VAS) are two instruments for measuring the intensity of breathlessness. Studies demonstrate that the slope and/or intercept of the power production-breathlessness relationship provide a valid, reliable, and responsive approach for measurement. Ratings of dyspnea during exercise are useful to determine the severity of breathing difficulty and to assess the efficacy of therapy.

Chronic lung diseases and the perception of breathlessness: a clinical perspective.

Breathlessness is an extremely common symptom. Its genesis is incompletely understood but is known to be largely determined by many of the mechanical factors associated with the act of breathing. As with all subjective sensations various other factors including volition, behavioural style and other cortical and subcortical factors play a part in its genesis. The relief of breathlessness is primarily directed at the underlying disorder. In those conditions and situations where specific therapy has little to offer or little impact it is reasonable to consider ways of reducing the perception of breathlessness by pharmacological means. However, to date there is no convincing evidence that use of drugs in the pursuit of the relief of breathlessness has any specific effect in modifying the perception of this often distressing symptom. Any reduction in breathlessness achieved in this way can be adequately explained in terms of a reduction in ventilation and other indices of respiratory mechanics.

Exertional breathlessness in patients with chronic airflow limitation. The role of lung hyperinflation.

There is considerable intersubject variability in the perceived intensity of breathlessness for a given level of activity among patients with chronic airflow limitation (CAL). To examine possible factors contributing to this variability we compared breathing pattern parameters, dynamic operational lung volumes, and Borg dyspnea ratings in 23 patients with severe CAL and in 10 healthy age-matched normal subjects during cycle ergometry to symptom-limitation. Patients with CAL had significantly (p < 0.01) higher levels of ventilation (% maximal voluntary ventilation) for a given work rate (slope of VE(%MVV)/WR(% pred max) = 1.51 +/- 0.18 versus 0.63 +/- 0.10; mean +/- SEM) and greater dynamic lung hyperinflation (DH) (change [delta] in end-expiratory lung volume [EELVdyn] = +0.31 +/- 0.11 L versus -0.16 +/- 0.22 L). Compared with normal subjects at a standardized VE (30 L/min), the CAL group was more breathless Borg = 4 +/- 1 versus 2 +/- 1, p < 0.01) and hyperinflated (EELVdyn = 75 +/- 3 versus 46 +/- 6% TLC, p < 0.001; end-inspiratory lung volume [EILVdyn] = 85 +/- 3 versus 67 +/- 5% TLC, p < 0.01). Within the CAL group, change in Borg ratings correlated with delta VE(%MVV) (r = 0.77, p < 0.001) and with slope of VE(%MVV)/WR(% pred max) (r = 0.48, p < 0.01). Regression analysis selected delta EILVdyn (or delta inspiratory reserve volume [delta IRVdyn]) from various dynamic ventilatory parameters as the strongest predictor of delta Borg (r = 0.63, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Does Cold Air Affect Exercise Capacity and Dyspnea in Stable Chronic Obstructive Pulmonary Disease?

Cold air may worsen asthmatic bronchoconstriction but can lessen breathlessness in normal individuals. Patients with COPD sometimes report improvement in their dyspnea in cold weather. We examined the effect of breathing cold air on exercise tolerance and the perception of breathlessness in 19 patients with stable COPD (age [+/- SD], 63 +/- 6 years; FEV1, 0.99 +/- 0.28 L) in a randomized open study. Patients exercised on a cycle ergometer breathing either room or cold air (-13 degrees C), breathlessness being assessed by Borg scaling. Peak exercise performance improved when breathing cold air (mean +/- SE), 46 +/- 6 W compared with 37 +/- 7 W (p < 0.05) while end-exercise breathlessness fell from 4.6 +/- 0.4 compared with 4.1 +/- 0.5 (p < 0.05) when breathing cold air. End-exercise ETCO2 was higher breathing cold air (6.1 +/- 0.3 kPa compared with 5.5 +/- 0.3 kPa) (p < 0.005). There was no difference in breathlessness at equivalent levels of ventilation. Cold air reduces breathlessness in COPD, probably by inducing relative hypoventilation.

Effect of residence at altitude on the perception of breathlessness on return to sea level in normal subjects.

1. The effect of residence at altitude on the perception of breathlessness after return to sea level was examined in normal subjects. Breathlessness (Borg scale), minute ventilation, respiratory frequency, tidal volume, 'oxygen pulse' (oxygen consumption/heart rate) and the ventilatory equivalent for oxygen (minute ventilation/oxygen consumption) were measured at exercise (cycle-ergometer) during 5 months of training before 4 weeks at 4000 m and during the 6 month period after return to sea level. 2. There was no change in the subjects' pattern of breathing (respiratory frequency and tidal volume) or 'oxygen pulse' after the period at altitude (P = 0.0001). The ventilatory equivalent for oxygen was increased at all work rates after the period at altitude (P = 0.02). This ratio was slightly lower after 6 weeks and had returned to normal by 6 months (P = 0.4). 3. During training there was no change in breathlessness score (P = 0.6). On return to sea level, breathlessness score relative to ventilation was reduced (P = 0.0001). This was maintained for at least 6 weeks, but not as long as 6 months. 4. This study has demonstrated that, in normal subjects, the otherwise stable and reproducible relationship between breathlessness and ventilation may be disrupted for several weeks by factors other than lung disease. 5. The mechanism responsible for this is not clear, but the observations are consistent with the hypothesis that prior experience of breathlessness may condition subsequent estimates of breathlessness.

Breathlessness perception in airways obstruction

Breathlessness perception in airways obstruction

Longitudinal Study of Near Fatal Asthma

The effect of careful follow-up and treatment modification for 45 patients with an admission for NFA has been studied. In 24 of 45, inciting events were recognized. BDP was used by 14 patients pre-NFA. In the mean follow-up of 863 days, there have been no deaths and seven patients have been readmitted with asthma. Six of the 45 patients have attained normal FEV1 and PC20H. Blunted perception of breathlessness, change in VAS ratio/change in FEV1, was found when first measured, but normalized to be no different than that of other asthmatic subjects as airway responsiveness became milder. The CO2 ventilatory responses did not differentiate individual NFA patients from non-NFA asthmatic or normal subjects. Comparison of the NFA cohort with the 1985 asthma admission cohort showed that an asthma admission within the last five years was a risk factor for a NFA episode.

Perception of breathlessness during bronchoconstriction induced by antigen, exercise, and histamine challenges.

Perception of breathlessness was studied in eight patients with mild, stable asthma after a histamine and exercise challenge performed before and 24 and 48 hours respectively after an antigen challenge. FEV1 and perception of breathlessness, evaluated by Borg's 10 point category scale, were measured after each administration of doubling antigen or histamine concentrations to achieve a greater than 20% fall in FEV1, and after six minutes of steady state exercise at 80% of maximal oxygen consumption (VO2max). The geometric mean provocative concentration of histamine causing a 20% fall in FEV1 (PC20) fell from 1.67 mg/ml before antigen challenge to 0.52 mg/ml 24 hours after the challenge. The median maximal % fall in FEV1 with exercise was 24.9% (range 10.5-40.5%) before and 30.6% (range 13.8-52.3%) 48 hours after antigen challenge. The median maximum % fall in FEV1 after antigen inhalation was 20.1% (range 13.3-35.2%) within the first hour; only two subjects had a late fall in FEV1 (23% and 58%). The median (range) of Borg scores obtained when FEV1 was reduced by 20% did not differ significantly for the three types of acute challenges: 1.25 (0.5-2.5) and 1.0 (0.5-3.0) after histamine tests, 1.0 (0.5-4.1) and 1.55 (0.5-2.0) after exercise, and 1.5 (0-3.0) after antigen challenge. In the two subjects who had a late response to antigen the Borg score was reduced for the same % fall in FEV1 as with the early response. It is concluded that the perception of breathlessness does not differ appreciably during the early response to histamine, antigen exposure, or exercise, but that it is reduced during the late asthmatic response. It was not influenced by previous antigen exposure, despite an increase in airway responsiveness.

Pulmonary Denervation in Humans: Effects on Dyspnea and Ventilatory Pattern during Exercise

The role of the pulmonary autonomic nerves in the mediation of respiratory sensation is unclear. Pulmonary neurogenic mechanisms may contribute to dyspnea either directly or indirectly via an influence on the pattern of ventilation. Using human heart-lung transplantation as a model of pulmonary denervation, we studied the ventilatory response, respiratory drive (P0.1), and sensation of breathlessness (modified Borg scale) during maximal incremental bicycle exercise. The subjects were four female heart-lung transplant recipients 3 to 9 months post-transplant and 10 age-matched control subjects. The ventilatory response to increasing CO2 output (VCO2) was higher (p less than 0.001) in transplant recipients than in control subjects, such that ventilation at peak exercise was similar in the two groups despite a lower peak VCO2 in transplant recipients. The ratio of tidal volume to inspiratory capacity increased with increasing ventilation in a similar fashion in both groups. Although the respiratory rate increased more quickly in transplant recipients, it was similar at peak ventilation in the two groups. Ventilatory timing and duty cycle at half-peak and peak ventilation were similar in transplant recipients and control subjects. Dyspnea ratings were not different between the two groups at similar levels of ventilation. Dyspnea as a function of P0.1 was also similar in transplant and control groups. These results indicate that pulmonary neurogenic mechanisms play a role in determining the level, but not the pattern, of ventilation during exercise. Furthermore, these pathways do not appear to contribute significantly to the perception of breathlessness in normal humans.

Influence of prior ventilatory experience on the estimation of breathlessness during exercise

1. The intensity of breathlessness was measured during exercise in nine normal subjects using a modified Borg scale to examine the effect of prior experience of breathlessness on subsequent estimates of breathlessness. 2. Each subject performed four exercise tests, each of which consisted of two identical runs of workload incrementation (run 1 and run 2). An inspiratory resistive load of 3.8 cmH2O s-1 l-1 was applied during the appropriate run of the exercise test to examine the effect of (a) prior experience of 'loaded' breathing on breathlessness estimation during 'unloaded' breathing, and (b) prior experience of 'unloaded' breathing on breathlessness estimation during 'loaded' breathing. Run 1 was the conditioning run: run 2 was the run in which the effect of conditioning was measured. 3. There was a good correlation between breathlessness and minute ventilation during both 'unloaded' breathing (median r = 0.93) and 'loaded' breathing (median r = 0.95). 4. The slope of the Borg score/minute ventilation relationship was greater during 'loaded' breathing than during 'unloaded' breathing (P less than 0.01). There was no difference in mean Borg score between 'unloaded' and 'loaded' breathing. 5. After a period of 'loaded' breathing during run 1, estimated breathlessness was significantly reduced during ensuing 'unloaded' breathing in run 2 (P less than 0.01) compared with the exercise test in which 'unloaded' breathing was experienced throughout both run 1 and run 2. 6. After a period of 'unloaded' breathing in run 1, estimated breathlessness was significantly increased during ensuing 'loaded' breathing in run 2 (P less than 0.01) compared with the exercise test in which the inspiratory load had already been experienced in run 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Prior Ventilatory Experience on Breathlessness Perception during Exercise

Effect of Prior Ventilatory Experience on Breathlessness Perception during Exercise

Effects of Oral Morphine on Breathlessness and Exercise Tolerance in Patients with Chronic Obstructive Pulmonary Disease

Previous studies have shown that opiates increase the maximal external work performed at exhaustion in patients with chronic obstructive pulmonary disease (COPD). The mechanism responsible for this improvement in exercise tolerance is unknown. The purpose of this study was to determine the effects of an oral morphine solution (0.8 mg/kg) on the exercise tolerance, perception of dyspnea, and arterial blood gases of patients with COPD. Thirteen eucapnic patients with stable COPD (FEV1 = 0.99 +/- 0.48) underwent duplicate incremental cycle ergometer tests to exhaustion (Emax) after the ingestion of placebo and after the ingestion of morphine. After the ingestion of morphine, the maximal workload increased by 18% (p less than 0.001) and the VO2 increased by 19.3% (p less than 0.001). Ten of the 13 patients had a higher ventilation at Emax after morphine ingestion. Despite the higher ventilation at Emax after morphine, the mean Borg score was not significantly higher. At Emax after morphine ingestion, the PaO2 (65.8 +/- 11.6 mm Hg) was significantly lower and the PaCO2 (43.5 +/- 8.3 mm Hg) was significantly higher than at Emax after placebo (71.9 +/- 15.5 and 38.3 +/- 8.5, respectively). When data at the highest equivalent workload were analyzed, the ventilation and the Borg scores were significantly lower, whereas the VO2 and VCO2 were comparable. From this study, we conclude that the administration of opiates can substantially increase the exercise capacity of patients with COPD. The improved exercise tolerance appears to be related to both a higher PaCO2 resulting in lowered ventilation requirements for a given workload and also to a reduced perception of breathlessness for a given level of ventilation.

Anxiety Disorder and Perception of Inspiratory Resistive Loads

Sensations of breathlessness in the absence of respiratory disease are common in anxiety disorders. Perceptions of breathlessness in eight patients with anxiety disorder were compared with eight normal control subjects, matched for age and sex, by the application of Steven's law to the magnitude of resistive load test. All subjects estimated the magnitudes of resistive loads to inspiration while peak inspiratory mouth pressures were monitored. Anxious patients' perceptions of the added loads were significantly less sensitive than normal, even though the effort, determined by peak inspiratory mouth pressure, in overcoming each load was normal. Correlations between estimates of resistive loads and peak inspiratory mouth pressure were significantly less for the anxious patients than for normal subjects. Thus, perception of breathlessness in anxiety disorders may be affected by factors not normally associated with breathlessness and may help account for the greater than normal variability in resistive load perception in respiratory disease.

Breathlessness and exercise in patients with cardiorespiratory disease.

Previous studies have led to the revival of the hypothesis that breathlessness is the perception of respiratory muscle effort and is present when the tension developed by muscles increases, when the muscles are weak, or when both conditions are present simultaneously. Using a category scale, the intensity of breathlessness was measured in 20 subjects (2 normal subjects and 18 patients) undergoing an incremental exercise test (50 to 100 kpm/min) to maximal capacity. The patients were selected to provide a heterogeneous group of pulmonary diseases, obesity, muscular weakness, and cardiac disease, with a wide variability in exercise capacity (250 to 1,900 kpm/min) and severity of dyspnea. Maximal inspiratory pressure (MIP), pleural pressure (Ppl), the extent of shortening of the inspiratory muscles as indicated by the tidal volume expressed as a percent of vital capacity (VT/VC), the rate of shortening as indicated by flow rate, the frequency of contraction as indicated by breathing frequency (fb), and the duty cycle (TI/Ttot) were measured throughout exercise to assess their relative contribution to the intensity of breathlessness. Using multifactorial analysis, the perception of breathlessness was significantly (p less than 0.01) related to the Ppl, inspiratory flow rate (VI), VT/VC, TI/Ttot, and fb. A multiple linear regression equation that included all these variables explained 69% of the variance, with no single factor being identified as uniquely predominant: Breathlessness = 3.0 (Ppl/MIP) + 1.2 (VI) + 4.5 (VT/VC) + 0.13 (fb) + 5.6 TI/Ttot) - 6.2 (R = 0.83). The intensity of effort required to produce a given pressure increases when the muscle is weak, when the velocity of contraction increases, or when the muscle shortens.(ABSTRACT TRUNCATED AT 250 WORDS)