Tracheostomy decannulation in severe acquired brain injury patients: The role of flexible bronchoscopy

INTRODUCTION AND OBJECTIVES

Subjects with severe acquired brain injury (sABI) require long-term mechanical ventilation and, as a consequence, the tracheostomy tube stays in place for a long time. In this observational study, we investigated to what extent the identification of late tracheostomy complications by flexible bronchoscopy (FBS) might guide clinicians in the treatment of tracheal lesions throughout the weaning process and lead to successful decannulation.

SUBJECTS AND METHODS

One hundred and ninety-four subjects with sABI admitted to our rehabilitation unit were enrolled in the study. All subjects received FBS and tracheal lesions were treated either by choosing a more suitable tracheostomy tube, or by laser therapy, or by steroid therapy, or by a combination of the above treatments.

RESULTS

Overall, 122 subjects (63%) were decannulated successfully. Our subjects received 495 FBSs (2.55 per subject) and as many as 270 late tracheostomy complications were identified. At least one complication was found in 160 subjects (82%). In only 11 subjects, late tracheostomy complications did not respond to the treatment and were the cause of decannulation failure.

CONCLUSIONS

In conclusion, in sABI patients FBS is able to guide successful tracheostomy weaning in the presence of late tracheostomy complications that could get in the way decannulation.

FRI0313 DOES INTERSTITIAL LUNG DISEASE REPRESENT A REAL COMORBIDITY IN SPONDYLOARTHRITIS PATIENTS? RESULTS FROM AN ULTRASOUND MONOCENTRIC PILOT STUDY

Background:

Interstitial lung disease (ILD) is a frequent complication in rheumatoid arthritis (RA) where it represents the most common extra-articular involvement (with a prevalence of about 10-60%) and the second cause of mortality (after cardiovascular diseases). Spondyloarthritides (SpA) are chronic arthritides that share with RA both a similar disease burden and similar therapeutical approaches. ILD evaluation is challenging, given the low sensitivity of X-ray and pulmonary function tests, and radiation linked to repetitive HRCT. Lung Ultrasound (LUS) has shown potential in the evaluation of ILD in autoimmune diseases.

Objectives:

To assess the prevalence of ILD in a cohort of SpA patients (pts) using LUS with respect to healthy controls (HC).

Methods:

Consecutive SpA out-pts were examined by LUS, applying the definition for pleural line irregularity (PLI) recently provided by the OMERACT taskforce for LUS in systemic sclerosis (1). Seventy-one intercostal spaces were studied (14 in the anterior chest, 27 lateral and 30 posterior) in all the pts/HC using an Esaote MyLab25 Gold US machine with a linear 7.5-10 MHz probe. The scoring system by Pinal-Fernandez et al (2) was applied and a total pleural score was calculated. Each patient answered to Italian-validated PROs on respiratory function (Leicester and Saint-George), global health (SF-36) and dyspnea (mMRC scale). Clinical data on disease-duration, disease-onset, disease-activity (at the moment of the examination) and MTX/biologics treatment were collected from the medical records.

Results:

Fifty-six SpA pts (35 psoriatic arthritis -PsA- and 21 ankylosing spondylitis -AS-) and 56 HC were studied. No significant differences were demonstrated between groups (SpA vs HC and PsA vs AS) for age, sex, BMI and smoking habits. The total pleural score was significantly higher in SpA pts than in HC (20.9±11.8 vs 10.3±7.7; p<0.001). A positive correlation was found between total PLI score and PLI score from anterior, posterior and lateral chest. The posterior part of the chest showed a higher PLI score than the anterior and lateral one (with the latter resulting to be significantly lower than the posterior PLI score). Higher differences in the PLI average value between SpA pts and HC were registered for posterior and anterior part of the chest. No differences were found between PsA and AS (with a not statistically significant difference in the posterior PLI score, which was slightly higher in AS pts) (Tab.I).

Table 1.

average PLI score (N±SD)

TotalAnteriorPosteriorLateralHC10.3 ± 7.74 ± 3.25 ± 3.71.4 ± 2.2PsA20.1 ± 12.56.8 ± 3.910.2 ± 6.92.9 ± 4.1AS22.1 ± 10.77 ± 2.812 ± 9.53 ± 3.1

Conclusion:

LUS examination shows a higher amount of PLI in SpA with respect to HC.

References:

[1]Delle Sedie A et al. Ann Rheum Dis 2019;78(Suppl 2):A834

[2]Pinal-Fernandez I et al. Clin Exp Rheumatol 2015;33(4 Suppl 91):S136-41

Disclosure of Interests:

Andrea Delle Sedie Speakers bureau: MSD, Lilly, Novartis, Abbvie, Celgene, Emanuele Calabresi: None declared, Ilaria Romagnoli: None declared, Linda Carli: None declared, Marta Mosca: None declared

MAPEAMENTO DA VULNERABILIDADE E RISCOS DE CONTAMINAÇÃO DAS ÁGUAS SUBTERRÂNEAS NA REGIÃO DO PONTAL DO PARANAPANEMA (UGRHI-22)

Dentre os principais riscos que o agrohidronegócio traz para a região do Pontal do Paranapanema (SP) estão os relacionados ao uso indiscriminado de agrotóxicos. A utilização de defensivos agrícolas aliada ao manejo incorreto pode acarretar na contaminação das águas subterrâneas, e consequentemente refletir prejudicialmente na saúde humana e ambiental. O Pontal do Paranapanema (SP) possui uma recente expansão da cultura da cana-de-açúcar, iniciada nos anos 2000. Recoberta por sedimentos do aquífero Bauru, toda região pode ser considerada como naturalmente vulnerável, já que é um aquífero com recarga direta. Sendo assim, o objetivo deste trabalho foi avaliar a vulnerabilidade natural do Aquífero Bauru a partir do método GOD e realizar estimativas de contaminação de água subterrânea por agrotóxicos utilizados na produção de cana-de-açúcar, a partir do software ARAquá, verificando o potencial de contaminação no Pontal do Paranapanema. Os resultados mostraram que apesar de uma expansão nos cultivos superior a 1.000 % em área plantada, a classe de alta vulnerabilidade foi que apresentou menor avanço das áreas de cultivo de cana-de-açúcar. Ao que se refere as simulações realizadas, foi possível concluir que não houveram concentrações de ingrediente ativo estimadas acima do valor para o padrão de potabilidade na região. O agrotóxico que mais se destacou com maiores valores de concentração nas estimativas realizadas foi o Tebuthiuron, apresentando risco às plantas aquáticas e animas em risco de extinção.

Chest wall kinematics in young subjects with Pectus excavatum

Quantifying chest wall kinematics and rib cage distortion during ventilatory effort in subjects with Pectus excavatum (PE) has yet to be defined. We studied 24 patients: 19 during maximal voluntary ventilation (MVV) and 5 during MVV and cycling exercise (CE). By optoelectronic plethysmography (OEP) we assessed operational volumes in upper rib cage, lower rib cage and abdomen. Ten age-matched healthy subjects served as controls. Patients exhibited mild restrictive lung defect. During MVV end-inspiratory and end-expiratory volumes of chest wall compartments increased progressively in controls, whereas most patients avoided dynamic hyperinflation by setting operational volumes at values lower than controls. Mild rib cage distortion was found in three patients at rest, but neither in patients nor in controls did MVV or CE consistently affect coordinated motion of the rib cage. Rib cage displacement was not correlated with a CT-scan severity index. Conclusions, mild rib cage distortion rarely occurs in PE patients with mild restrictive defect. OEP contributes to clinical evaluation of PE patients.

Role of hyperinflation vs. deflation on dyspnoea in severely to extremely obese subjects

AIM

To test the hypothesis that obese individuals may either hyperinflate or deflate the lung when exercising. In both cases breathlessness is an inescapable consequence.

METHODS

Ventilatory variables, end-expiratory lung volume and end-inspiratory lung volume, and dyspnoea score (Borg scale) were studied in 20 class II-III obese subjects and 14 healthy controls during incremental symptom-limited cycle exercise.

RESULTS

Ventilation increased with increasing work rate, in obese and in control subjects; most obese subjects had to increase end-expiratory lung volume to escape from flow limitation; in contrast, like controls, a few subjects deflated the lung on heavy-to-peak exercise. Dyspnoea was equal in degree at anaerobic threshold and peak exercise in obese as in control subjects, and in obese who hyperinflated as in those who deflated the lung. In particular, end-expiratory lung volume at baseline (r = -0.84, P = 0.04) was negatively correlated with changes in Borg score in obese who did not hyperinflate: the lower the former the higher the latter. On the other hand, tidal volume (r = 0.54, P = 0.045) and decrease in inspiratory reserve volume (r = 0.59, P = 0.028) were positively correlated with the Borg score in obese subjects who hyperinflated. No other independent variable correlated with the Borg score.

CONCLUSIONS

We conclude that not all obese subjects had to increase end-expiratory lung volume on heavy-to-peak exercise. Changes in dyspnoea for unit changes in ventilation were similar in obese who did hyperinflate as well as in those who did not, suggesting that the increase in respiratory neural drive, associated with an increase in ventilation, is an important source of dyspnoea in obese as well as in control subjects.

Chest wall kinematics during cough in healthy subjects

AIM

The study of kinematics of the chest wall (CW) could allow us to define the relative deflationary contribution of its compartments during fits of coughing. We hypothesized that if forces applied to the lung apposed rib cage are not commensurate with those applied to the abdomen-apposed rib cage, cough could result in rib cage distortion.

METHODS

In 12 (five women) healthy subjects we evaluated the volumes of CW (Vcw) and its compartments: the lung apposed rib cage, the abdomen apposed rib cage and the abdomen, by optoelectronic plethysmography. The loop of volume of the lung apposed rib cage/volume of the abdomen apposed rib cage allowed the calculation of mean rib cage distortion, resulting in a dimensionless number which, when multiplied by 100, gives percentage distortion. Each subject performed voluntary single and prolonged coughing efforts at functional residual capacity (FRC) and after maximal inspiration (max). The normal level of mean distortion was set at <0.5%.

RESULTS

The three compartments contributed to reducing end-expiratory Vcw during cough at FRC and prolonged maximum cough, with the latter resulting in the greatest CW deflation. Mean rib cage distortion did not differ between men and women (P > 0.1), but tended to significantly increase from single to prolonged Cough Max (1.3% +/- 1.0 vs. 2.3% +/- 1.6, respectively; P = 0.06).

CONCLUSION

Rib cage distortion may ensue during coughing, probably as a result of uneven distribution of forces applied to the rib cage.

Chest wall kinematics, respiratory muscle action and dyspnoea during arm vs. leg exercise in humans

AIM

We hypothesize that different patterns of chest wall (CW) kinematics and respiratory muscle coordination contribute to sensation of dyspnoea during unsupported arm exercise (UAE) and leg exercise (LE).

METHODS

In six volunteer healthy subjects, we evaluated the volumes of chest wall (V(cw)) and its compartments, the pulmonary apposed rib cage (V(rc,p)), the diaphragm-abdomen apposed rib cage (V(rc,a)) and the abdomen (V(ab)), by optoelectronic plethysmography. Oesophageal, gastric and trans-diaphragmatic pressures were simultaneously measured. Chest wall relaxation line allowed the measure of peak rib cage inspiratory muscle, expiratory muscle and abdominal muscle pressures. The loop V(rc,p)/V(rc,a) allowed the calculation of rib cage distortion. Dyspnoea was assessed by a modified Borg scale.

RESULTS

There were some differences and similarities between UAE and LE. Unlike LE with UAE: (i) V(cw) and V(rc,p) at end inspiration did not increase, whereas a decrease in V(rc,p) contributed to decreasing CW end expiratory volume; (ii) pressure production of inspiratory rib cage muscles did not significantly increase from quiet breathing. Not unlike LE, the diaphragm limited its inspiratory contribution to ventilation with UAE with no consistent difference in rib cage distortion between UAE and LE. Finally, changes in abdominal muscle pressure, and inspiratory rib cage muscle pressure predicted 62% and 41.4% of the variability in Borg score with UAE and LE, respectively (P < 0.01).

CONCLUSION

Leg exercise and UAE are associated with different patterns of CW kinematics, respiratory muscle coordination, and production of dyspnoea.

Breathing pattern and kinematics in normal subjects during speech, singing and loud whispering

AIMS

We used for the first time a non-invasive optoelectronic plethysmography to assess breathing movements and to provide a quantitative description of chest wall kinematics during phonation.

METHODS

Volumes of different chest wall compartments (abdomen and lung apposed to rib cage and abdomen) were assessed using optoelectronic plethysmography in 16 normal Italians (eight men) during reading, singing and high-effort whispering (HW).

RESULTS

During phonation the breathing pattern was different from quiet breathing and exercise. (1) During phonation, tidal volume and expiratory time increased while inspiratory time decreased. The expiratory volume changes and flows during HW were considerably greater than during vocalization. During HW, the overall end-expiratory thoracic volume significantly decreased as a result of decreased volume of all compartments and essentially impinged on the maximal expiratory flow-volume curve. (2) While, as previously shown, during exercise the expired volume is due entirely to the abdomen, during phonation all three chest wall compartments contribute to it. Under all conditions studied breathing was, on average, more costal in females than in males but this was mainly related to different size rather than gender per se.

CONCLUSIONS

Physical characteristics have a greater importance than gender in determining breathing pattern and chest wall kinematics during phonation. The activity of the control of expiration during phonation is more complex than during exercise.

Chest wall kinematics and respiratory muscle action in ankylosing spondylitis patients

No direct measurements of the pressures produced by the ribcage muscles, the diaphragm and the abdominal muscles during hyperventilation have been reported in patients with ankylosing spondylitis. Based on recent evidence indicating that abdominal muscles are important contributors to stimulation of ventilation, it was hypothesised that, in ankylosing spondylitis patients with limited ribcage expansion, a respiratory centre strategy to help the diaphragm function may involve coordinated action of this muscle with abdominal muscles. In order to validate this hypothesis, the chest wall response to a hypercapnic/hyperoxic rebreathing test was assessed in six ankylosing spondylitis patients and seven controls by combined analysis of: 1) chest wall kinematics, using optoelectronic plethysmography, this system is accurate in partitioning chest wall expansion into the contributions of the ribcage and the abdomen; and 2) respiratory muscle pressures, oesophageal, gastric and transdiaphragmatic (Pdi); the pressure/volume relaxation characteristics of both the ribcage and the abdomen allowed assessment of the peak pressure of both inspiratory and expiratory ribcage muscles, and of the abdominal muscles. During rebreathing, chest wall expansion increased to a similar extent in patients to that in controls; however, the abdominal component increased more and the ribcage component less in patients. Peak inspiratory ribcage, but not abdominal, muscle pressure was significantly lower in patients than in controls. End-inspiratory Pdi increased similarly in both groups, whereas inspiratory swings in Pdi increased significantly only in patients. No pressure or volume signals correlated with disease severity. The diaphragm and abdominal muscles help to expand the chest wall in ankylosing spondylitis patients, regardless of the severity of their disease. This finding supports the starting hypothesis that a coordinated response of respiratory muscle activity optimises the efficiency of the thoracoabdominal compartment in conditions of limited ribcage expansion.

Chest wall kinematics and respiratory muscle coordinated action during hypercapnia in healthy males

The present study was designed to verify whether during hypercapnic stimulation, as we had previously found during exercise or walking, the partitioning of the respiratory motor output is equally distributed to the muscles of chest wall compartments to assist diaphragm function. We studied chest wall kinematics and respiratory muscle recruitment in seven healthy men during rebreathing of a hypercapnic-hyperoxic gas mixture (CO(2) RT). Data were compared with those previously obtained during either cycling exercise or walking. The chest wall volume ( Vcw), assessed by optoelectronic plethysmography (OEP), was modeled as the sum of the volumes of the lung-apposed rib cage ( Vrc,p), diaphragm-apposed rib cage ( Vrc,a) and abdomen ( Vab). Esophageal ( Pes), gastric ( Pga) and transdiaphragmatic ( Pdi= Pga- Pes) pressures were simultaneously recorded. Velocity of shortening ( V') and power ( W'= Px V') of the diaphragm ( W'di), rib cage muscles ( W'rcm) and abdominal muscles ( W'abm) were also calculated. During CO(2) RT the progressive increase in end-inspiratory Vcw resulted from an increase in both end-inspiratory Vrc,p and Vrc,a, while the progressive decrease in end-expiratory Vcw was entirely due to the decrease in end-expiratory Vab. The increase in Vrc,p was proportionally slightly greater than that in Vrc,a. The end-inspiratory increase and end-expiratory decrease in Vcw were accounted for by inspiratory rib cage (RCM,i) and abdominal (ABM) muscle recruitment, respectively. W'di, W'rcm and W'abm progressively increased. However, while most of W'di was expressed in terms of velocity of shortening, most of W'rcm and W'abm was expressed as force or pressure. A comparison of CO(2) results with data obtained during exercise revealed: (1). a gradual vs. an immediate response, (2). a similar decrease in Vab,e and Pabm, (3). an apparent lack of any difference in ABM recruitment, (4). less gradual ABM relaxation, (5). no drop in Pdi but a similar Wdi change and decrease in pressure-to-velocity ratio of the diaphragm. We have found that in healthy humans: (1). the increased motor output with hypercapnia is equally distributed between RCM and ABM to minimize transdiaphragmatic pressure and (2). data on chest wall kinematics and respiratory muscle recruitment are only partly in line with those obtained during walking or cycling exercise.

Chest wall kinematics during chemically stimulated breathing in healthy man

Chest wall compartment kinematics and respiratory muscle coordinate activity, during either hypercapnia or hypoxia, have not been comparatively assessed in healthy humans. We assessed the displacement volume of the chest wall (Vcw) in 5 normal subjects during hypoxic-normocapnic and hypercapnic-hyperoxic rebreathing by using linearized magnetometers. Vcw was divided into displacement volumes of the rib cage (Vrc) and the abdomen (Vab). Esophageal (Pes) and gastric (Pga) pressures were simultaneously recorded and transdiaphragmatic pressure (Pdi) was calculated by subtracting Pes from Pga. Pressure swings (sw) from end expiration (EE) to end inspiration (EI) were also calculated. During both hypoxia and hypercapnia, from quiet breathing to 40 L/min VE, Vrc,EI increased consistently but Vrc,EE, and Vab,EI did not. Moreover, Vab,EE decreased significantly during hypercapnia and remained unchanged during hypoxia. PesEI decreased (more negative values) and PesEE increased (less negative values) during either stimulus, while PgaEE increased with hypercapnia. Pdisw, calculated as the difference between PdiEE and PdiEI, increased significantly with both hypercapnia and hypoxia ( p = 0.002 for both). On the plot of Pes vs Pga, the slope of a line from end expiratory to end inspiratory lung volume between 20 and 40 L/min VE progressively increased during hypercapnia indicating increasing rib cage muscle (RCM) contribution to inspiratory pressure swings relative to the diaphragm. From these results we conclude that in healthy man: (i) with both chemical stimuli RCM contribution accounts for increase in Vrc displacement; (ii) with hypercapnia, the decrease in Vab,EE displacement indicates abdominal muscle (ABM) contribution to tidal volume; (iii) RCM and ABM assist the diaphragmatic function during hypercapnic stimulation.

Measures of perception of bronchoconstriction and clinical and functional data are not interrelated in asthma

BACKGROUND

Sensitivity and absolute perceptual magnitude characterize the perception of bronchoconstriction (PB).

OBJECTIVES

To define whether clinical and functional characteristics and level of bronchial hyperresponsiveness (BHR) correlate with these two PB indexes during bronchial challenge in asthma.

METHODS

PB on both the Borg scale and the visual-analogue scale (VAS) was assessed in 45 consecutive asthmatics during a methacholine-induced decrease in forced expiratory volume in 1 s (FEV(1)) and specifically quantified as Borg and VAS slope, as a measure of sensitivity, whereas scores at a 20% FEV(1) decrease (PB(20)) were assessed as a measure of absolute perceptual magnitude. Clinical score and BHR were also assessed.

RESULTS

PB(20) related to slope on both the Borg scale and the VAS (p < 0.0001). PB(20) and slope related neither to clinical score nor to baseline functional data on both scales. The relationship between the level of BHR and PB(20) on either scale was of questionable clinical significance (r(2) = 7%).

CONCLUSIONS

Irrespective of the scale employed, our data indicate the need for directly assessing PB rather than deriving it from clinical and functional data and level of BHR.

Breathing retraining and exercise conditioning in patients with chronic obstructive pulmonary disease (COPD): a physiological approach

In this review we shall consider the commonest techniques to reduce dyspnea that are being applied to patients with chronic obstructive pulmonary disease (COPD) subjected to a pulmonary rehabilitation program (PRP). Pursed lip breathing (PLB) and diaphragmatic breathing (DB) are breathing retraining strategies employed by COPD patients in order to relieve and control dyspnea. However, the effectiveness of PLB in reducing dyspnoea is controversial. Moreover, DB may be associated with asynchronous and paradoxical breathing movements, reflecting a decrease in the efficiency ofthe diaphragm. Exercise training (EXT) is a mandatory component of PRP.EXT has been shown to improve exercise performances and peripheral muscle strength. Recent studies have focused on the effect of EXT on breathlessness. However, concerns persist as to whether the decreased sensation of dyspnea for a given exercise stimulus is principally due to psychological benefits of rehabilitation or to improved physiological ability to perform exercise. The effect of EXT on breathlessness may be reinforced by inhaling oxygen. However, two studies have recently shown that breathing supplemental oxygen during training has either a marginal effect or no advantage over training. In a comprehensive PRP, strength training (ST) and arm endurance training (AET) could have a role in decreasing peripheral muscle weakness and metabolic and ventilatory requirements for AET. The role of unloading the respiratory muscles during EXT has to be

Dyspnea, respiratory function and sputum profile in asthmatic patients during exacerbations

Dyspnea is often used as a marker of asthma severity although a wide variation in dyspnea perception associated with bronchoconstriction (PB) has been described in asthmatic patients. Our hypothesis is that changes of airway inflammation, airway narrowing and hyperinflation may account for a part of the variability of breathlessness in spontaneous asthma attack. In asthmatic patients with exacerbation of the disease, we evaluated respiratory function, dyspnea (using visual Analogue Scale--VAS) and peak expiratory flow (PEF) values and variability (amplitude % mean), and sputum cellular and biochemical profile before (day I) and after (day II) therapy with i.v. corticosteroids and inhaled beta2-agonists, as appropriate. By day II, forced expiratory volume in 1 s (FEV1), inspiratory capacity (IC), PEF or VAS values and variability, sputum eosinophils and eosinophilic cationic protein (ECP) had improved. Improvement of dyspnea expressed as a decrease in VAS and reduction in variability of dyspnea sensation significantly correlated with increase in FEV1 %predicted value (%pv) (P=0.03; p=0.72 and P=0.02; p=0.74, respectively). No significant correlation was found between IC and VAS either in absolute values or as changes from days I and II, nor between sputum outcomes and PEF or VAS, regardless of how they were measured. We conclude that in acute asthmatic patients, dyspnea measurement, functional measurements and sputum analysis may be useful in monitoring disease activity, response to therapy and can provide different information on the state of the disease.

The diaphragm and dyspnea during chemically stimulated breathing in a subset of patients with diabetes

In patients with insulin-dependent diabetes mellitus (IDDM) isolated peripheral airway involvement may give rise to inspiratory threshold load (ITL) contributing to dyspnea. Based on the reported evidence of a greater increase in end-expiratory lung volume (EELV) with hypoxia than with hypercapnia in IDDM, we wondered whether, and to what extent in the two conditions, EELV contribute to perception of dyspnea (PD). We studied five nonsmokers aged between 19 and 45, with IDDM under good metabolic control and five normal control subjects matched for age. In each patient, we evaluated the electromyographic activity of the diaphragm (Edi), the swings of esophageal (Pessw), gastric (Pgsw), and transdiaphragmatic (Pdisw = Pgsw-Pessw) pressures; PD was assessed by a modified Borg scale during hypercapnic-hyperoxic (HCH) and hypoxic-isocapnic (HIC) stimulation. Change in inspiratory capacity (IC) was considered the mirror image of increase in EELV, that is, dynamic hyperinflation (DH), while intrinsic positive end inspiratory pressure (PEEPi) was measured as an index of inspiratory threshold load (ITL). In controls, Edi and Pdi but not their ratio (Edi/Pdi) related to Borg. In patients the following was found: (1) with each of the two stimuli, for any given Edi, Pdi, and Edi/Pdi ratio, there was greater Borg than in controls, (2) a similar increase in ITL and DH with HCH and HIC, (3) Edi/Pdi related to Borg similarly with HCH as with HIC. In conclusion, in controls, Edi and Pdi were associated with the perception of dyspnea similarly with the two chemical stimuli. In this subset of patients with IDDM, Edi/Pdi ratio throughout increase in EELV and ITL was found to affect the perception of dyspnea in hypoxia to a similar extent as in hypercapnia.

Perception of bronchoconstriction in smokers with airflow limitation

To our knowledge, no data have been provided as to whether and to what extent dynamic hyperinflation, through its deleterious effect on inspiratory muscle function, affects the perception of dyspnoea during induced bronchoconstriction in patients with chronic airflow obstruction. We hypothesized that dynamic hyperinflation accounts in part for the variability in dyspnoea during acute bronchoconstriction. We therefore studied 39 consecutive clinically stable patients whose pulmonary function data were as follows (% of predicted value): vital capacity (VC), 97.8% (S.D. 16.0%); functional residual capacity, 105.0% (18.8%); actual forced expiratory volume in 1 s (FEV(1))/VC ratio, 56.1% (6.3%). Perception of dyspnoea using the Borg scale was assessed during a methacholine-induced fall in FEV(1). The clinical score and the treatment score, the level of bronchial hyper-responsiveness and the cytological sputum differential count were also assessed. In each patient, the percentage fall in FEV(1) and the concurrent Borg rating were linearly related, with the mean slope (PD slope) being 0.09 (0.06). The percentage fall in FEV(1) accounted for between 41% and 94% of the variation in the Borg score. At a 20% fall in FEV(1), the decrease in inspiratory capacity (Delta IC) was 0.156 (0.050) litres. Patients were divided into three subgroups according to the PD slope (arbitrary units/% fall in FEV(1)): subgroup I [eight hypoperceivers; PD slope 0.026 (0.005)], subgroup II [26 moderate perceivers; 0.090 (0.037)] and subgroup III [five hyperperceivers; 0.200 (0.044)]. By applying stepwise multiple regression analysis with the PD slope as the dependent variable, and other characteristics (demographic, clinical and functional characteristics, smoking history, level of bronchial hyper-responsiveness and sputum cytological profile) as independent variables, Delta IC (r(2)=45%, P<0.00001) and to a lesser extent treatment score (r(2)=17.3%, P<0.0006), and to an even lesser extent age (r(2)=3%, P<0.05), independently predicted a substantial amount (r(2)=65.27%, P<0.00001) of the variability in the Borg slope. Thus acute hyperinflation, and to a lesser extent treatment score and age, account in part for the variability in the perception of dyspnoea after accounting for changes in FEV(1) during bronchoconstriction in patients with chronic airflow obstruction.

Do inhaled corticosteroids affect perception of dyspnea during bronchoconstriction in asthma?

BACKGROUND

Some of the disagreements on the perception of dyspnea (PD) during bronchoconstriction in asthma patients could depend on the interrelationships among the following: (1) the influence of baseline airflow obstruction on the patient's ability to detect any further increase in airway resistance; (2) the effect of eosinophilic inflammation on the airway; (3) bronchial hyperresponsiveness (BHR); and (4) the effect of inhaled corticosteroids (ICSs).

OBJECTIVE

We hypothesized that if the inflammation of the airway wall influences to some extent and in some way the PD in asthma patients, ICSs reverse the effect of airway inflammation on the PD.

METHODS

We studied 100 asthma patients who were divided into the following four groups: patients with obstruction who were either ICS-naive (group I) or were treated with ICSs (group II); and nonobstructed patients who were either ICS-naive (group III) or were treated with ICSs (group IV). PD on the visual analog scale (VAS) was assessed during a methacholine-induced FEV(1) decrease and specifically was quantified as the VAS slope and score at an FEV(1) decrease of 5 to 20%. BHR was assessed in terms of the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)). Eosinophil counts in induced sputum samples also were performed. Regression analysis, univariate analysis of variance, and factor analysis were applied for statistical evaluation.

RESULTS

For a 5 to 20% fall in FEV(1) from the lowest point after saline solution induction, VAS score was lowest in group II, slightly higher in group I, slightly higher still in group IV, and the highest in group III. In the patients as a whole, BHR related to PD, but age, clinical score, duration of the disease, and presence of baseline airway obstruction did not. In patients with obstruction who were treated with ICSs, eosinophil counts related to PD negatively. Factor analysis yielded the following four factors that accounted for 70% of the variance in the data: ICS; eosinophil counts; FEV(1); and PC(20) loaded on separated factors with PD loading on the same factors as PC(20). The post hoc analysis carried out dividing the patients into ICS-treated and ICS-naive, showed that in the former group eosinophil counts and BHR proved to be factors negatively associated with PD, while in the latter group eosinophil counts were positively associated with PD.

CONCLUSIONS

We have shown that eosinophilic inflammation of the airway wall may increase PD and that the association of eosinophil counts with ICSs may result in lessening the PD.

Perception of dyspnea in patients with neuromuscular disease

BACKGROUND

The perception of dyspnea is not a prominent complaint of resting patients with neuromuscular disease (NMD). To our knowledge, no study has been addressed at evaluating the interrelationships among lung mechanics, respiratory motor output, and the perception of dyspnea in patients with NMD receiving ventilatory stimulation.

MATERIAL

Eleven patients with NMD (mean +/- SD age, 44 +/- 11.8 years; 5 men) of different etiology and a group of normal subjects matched for age and sex (control subjects).

METHODS

While patients were breathing room air, lung volumes, arterial blood gases, the pattern of breathing (minute ventilation [E], tidal volume [VT], respiratory frequency, inspiratory time), and maximal (less negative) esophageal pressure during a sniff maneuver (Pessn), as an index of inspiratory muscle strength, were measured. Then we evaluated the response to hypercapnic-hyperoxic stimulation (hypercapnic-hyperoxic rebreathing test [RT]) in terms of breathing pattern, inspiratory swing of pleural pressure (Pessw), and inspiratory effort (Pessw[%Pessn]). During the RT, dyspnea was assessed every 30 s using a modified Borg scale (0 to 10).

RESULTS

Pulmonary volumes were reduced in seven patients, and PCO(2) was out of proportion to E in four patients. Group Pessn was 42.8 +/- 23.6 cm H(2)O in patients and 107 +/- 20.4 cm H(2)O in control subjects (p < 0.001). Dynamic elastance (Eldyn) [p = 0.0016] and Pessw(%Pessn) [p < 0.0005] were higher in patients. During the RT, Borg/CO(2), Pessw(%Pessn)/CO(2), and Borg/Pessw(%Pessn) were similar in the two groups, while E/CO(2) and VT/CO(2) were lower in patients (p < 0.0002 for both). As a consequence, for unit change in VT (percentage of predicted vital capacity [%VC]), greater changes in Pessw(%Pessn) were associated with greater Borg scores in patients. Baseline Eldyn related to Pessw(%Pessn)/VT(%VC) during hypercapnia (r(2) = 0.85), an index of neuroventilatory coupling of the ventilatory pump (NVC). NVC predicted a good amount of the variability in Borg/E (r(2) = 0.46, p < 0.02).

CONCLUSIONS

In this subset of NMD patients during hypercapnic stimulation, a normal inspiratory motor output per unit change in PCO(2) results in a shallow breathing pattern. The consequent impairment of NVC underlies the higher scoring of dyspnea in these patients.

Airway obstruction and chronic exertional dyspnoea in patients with persistent bronchial asthma

In patients with COPD, flow limitation (FL) predicts chronic exertional dyspnoea (CED) better than routine spirometry. Whether, and to what extent, FL and CED are overlapping quantities in chronic asthma has not yet been defined. Forty consecutive clinically stable asthmatic patients without smoking history or cardiopulmonary disorders, were studied. In each subject respiratory function, including static and dynamic pulmonary volumes, was evaluated; maximal (MEFV) and partial (PEFV) expiratory V'-V curves and isovolumic partial to maximal flow ratio (M/P). FL was assessed in a seated patient by comparing tidal and PEFV curves; FL was detected when tidal flows were superimposed or exceeded those obtained during PEFV curves, and was expressed as a percentage of the expired control tidal volume (V(T)) affected by flow limitation (FL% VT). Dyspnoea was assessed by both MRC scale and Baseline Dyspnoea Index (BDI) focal score. Half of the patients were found to have FL. They were older, more dyspnoeic and more obstructed (P<0.03 - P<0.000005) than the non-FL group. FEV1, vital capacity (VC), age, body mass index, FL and M/P ratio were all related to dyspnoea scores. FL was significantly related to FEV1 (r = - 0.59). Multiple regression analysis showed that FEV1 (P=0.003, r2= 15-3% and P = 0.004, r2= 20.3%) and age (P = 0.0006, r2 = 26.8% and P = 0.016, r2 = 11%) independently predicted a part of the variance of MRC (P = 0.0001, r2 = 42.1%) and BDI (P = 0.0008, r2 = 31.3%), respectively. With dyspnoea scale being the gold standard, diagnostic accuracy (sensitivity and specificity) by ROC (receiver operating characteristics) analysis was similar for FEV1 and FL. The results indicate that FL may be present in this subset of asthmatics. CED may not be easily explained by abnormalities of routine spirometry or FL, the largest part of the CED variance remained unexplained. Thus, routine spirometry, FL and CED in patients with bronchial asthma are only partially overlapping quantities which need to be assessed separately.

Perception of bronchoconstriction and bronchial hyper-responsiveness in asthma

The inter-relationship between the perception of bronchoconstriction, bronchial hyper-responsiveness and temporal adaptation in asthma is still a matter of debate. In a total of 52 stable asthmatic patients, 32 without airway obstruction ¿forced expiratory volume in 1 s (FEV(1))/vital capacity (VC) 84.1% (S.D. 7.9%), and 20 with airway obstruction [FEV(1)/VC 60% (4%)], we assessed the perception of bronchoconstriction during methacholine inhalation by using: (i) the slope and intercept of the Borg and VAS (Visual Analog Scale) scores against the decrease in FEV(1), expressed as a percentage of the predicted value; and (ii) the Borg and VAS scores at a 20% decrease in FEV(1) from the lowest post-saline level (PB(20)). Bronchial hyper-responsiveness was assessed as the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)FEV(1)). The reduction in FEV(1) was significantly related to the Borg and VAS scores, with values for the group mean slope and intercept of this relationship of 0.13 (S.D. 0.08) and -1.1 (3.02) for Borg, and 1.5 (1.19) and -12.01 (35) for VAS. PB(20) was 3 (1.75) with Borg scores and 34.6 (20.5) with VAS scores. Compared with the subgroup without airway obstruction, the obstructed subgroup exhibited similar slopes, but lower Borg and VAS intercepts. For similar decreases in FEV(1) (5-20% decreases from the lowest post-saline values), the Borg and VAS scores were lower in the non-obstructed than in the obstructed subgroup. PC(20)FEV(1) was significantly related to both Borg PB(20) and VAS PB(20) when considering all patients. When assessing the subgroups, PC(20)FEV(1) was related to Borg PB(20) and VAS PB(20) in the non-obstructed subjects, but not in the obstructed subjects. In neither subgroup was the log of the cumulative dose related to the Borg and VAS scores at the end of the test. We conclude that, unlike in previous studies, the ability to perceive acute bronchoconstriction may be reduced as background airflow obstruction increases in asthma. Bronchial hyper-responsiveness did not play a major role in perceived breathlessness in patients without airway obstruction, and even less of a role in patients with obstruction. The cumulative dose of agonist did not appear to influence the perception of bronchoconstriction.

Hypoxic and hypercapnic breathlessness in patients with type I diabetes mellitus

STUDY OBJECTIVES

The putative role of the performance of inspiratory muscles and breathing pattern in inducing dyspnea has been recently assessed during hypoxic stimulation in patients with type I diabetes (IDDM). Compared to a hypoxic stimulus, a hypercapnic stimulus, which may differently affect the pattern of breathing, could therefore modulate the coupling between respiratory effort and ventilatory output, which is involved in dyspnea sensation.

SUBJECTS

Eight stable patients aged 19 to 48 years old, with IDDM (duration of disease, 36 to 240 months) and no smoking history, cardiopulmonary involvement, or autonomic neuropathy; and an age- and sex-matched control group.

MEASUREMENTS

Pulmonary volumes, diffusing capacity of the lung for carbon monoxide, time and volume components (tidal volume [VT] and respiratory frequency), dynamic elastance (Eldyn), and swings in pleural pressure (Pessw) were measured. Maximal inspiratory pleural pressure (Pes) during a maximal sniff maneuver (Pessn), respiratory muscle effort or output (Pessw%Pessn), tension time index (TTI) = TI/total breathing cycle time x Pessw(%Pessn), and swing in Pes during VT as a percentage of Pessn were also evaluated. Dyspnea sensation was assessed by a modified Borg scale. Subjects were studied at baseline and during hypoxic and hypercapnic rebreathing tests.

RESULTS

Compared to control subjects, patients exhibited normal routine spirometric function and Pessn, but a higher Eldyn, indicating peripheral airway involvement. In patients, but not in control subjects, Eldyn increased during both chemical stimuli and increased more during hypoxia than during hypercapnia. Also, changes in both VT and Pessw(%Pessn) on changes in PCO(2) were lower, while changes in Pessw(%Pessn)/VT, an index of neuroventilatory dissociation (NVD) of the ventilatory pump, on changes in PCO(2) were greater. Changes in VT and NVD for unit change in arterial oxygen saturation were lower and higher, respectively. Changes in Borg scale per changes in NVD were greater during both stimuli. Furthermore, compared to hypoxic conditions, a greater VT for any level of both minute volume and Pessw(%Pessn), and lower changes in Borg scale on changes in Pessw(%Pessn) and Pessw(%Pessn)/VT were found in hypercapnia. Changes in NVD and Borg scale related to changes in Eldyn with both chemical stimuli.

CONCLUSIONS

In IDDM, the greater perception of dyspnea is associated with changes in inspiratory effort being out of proportion to changes in VT. The greater increase in Eldyn and the lower increase in VT may, in part, account for the greater perception of breathlessness during hypoxia.

Respiratory muscles in internal medicine

This review provides evidence that respiratory muscle abnormalities are present in many illnesses of internal medicine and emphasizes that clinicians should look for respiratory muscle weakness in many circumstances, particularly immunological disorders. Controversial results in hormonal diseases, metabolic diseases and abdominal disorders indicate areas for further research.

Reduction in bronchodilation following a deep inhalation is poorly related to airway inflammation in asthma

In patients with bronchial asthma, forced expiratory flows are differently sensitive to a previous volume history. A reduced ability of a deep inhalation (DI) to dilate obstructed airways has been hypothesized to be a physiological marker for the degree of airway responsiveness and to relate to the presence and magnitude of inflammation in the lung, even in mild stable asthma. However, there are at present doubts as to whether functional changes could be used as a substitute for airway inflammation studies. In order to investigate the interrelations among airway inflammation, bronchial hyperresponsiveness and effects of volume history, 58 consecutive asthmatics with mild to moderate asthma were studied. The effects of DI were assessed as the isovolumic ratio of flows from forced expiratory manoeuvres started from maximal (M) or partial (P) lung inflation. Airway inflammation was assessed by using induced sputum. Sputum was analysed for total and differential cell counts, and levels of eosinophil cationic protein (ECP) which reflects eosinophil activation. Airway responsiveness was assessed as the provocative concentration of histamine which caused a 20% fall in forced expiratory volume in one second (FEV1) from control (PC20). The M/P ratio was significantly related to ECP (r=-0.31, p<0.03) and eosinophils (r=-0.29, p<0.03), FEV1/vital capacity (VC) (r=0.32; p<0.01), clinical score (r=-0.33; p<0.03) and age (r=-0.41; p<0.0001). In a stepwise multiple regression analysis including age, score, baseline lung function, ECP, number of eosinophils and the response to beta2-agonist, age (p<0.037) predicted a small amount of the variance in M/P ratio (r2=0.12). It is concluded that volume history response is substantially independent of both sputum outcomes (inflammatory cell number and eosinophil cationic protein) and bronchial hyperresponsiveness; rather it seems to be associated with anthropometric characteristics. Functional aspects do not provide information on eosinophilic, probably central, airway inflammation.