Eficacia y seguridad de la respiración consciente para el tratamiento de distintas condiciones clínicas / Efficacy and safety of mindful breathing for the treatment of different clinical conditions

NOMBRE DE LA TÉCNICA CON PRETENDIDA FINALIDAD SANITARIA: Respiración consciente. DEFINICIÓN DE LA TÉCNICA E INDICACIONES CLÍNICAS: La respiración consciente consiste en estar presente de forma plena en el momento en que se realiza la respiración y sentir los efectos de esta sobre el cuerpo. Esta práctica podría aliviar la sensación de angustia o estrés a la persona que la realiza, ya que disminuye el ritmo cardíaco y frecuencia respiratoria a nivel físico. Este informe ha investigado la utilidad de esta práctica en el estrés, la ansiedad y la depresión, así como en otras patologías como la disnea (dificultad respiratoria o falta de aire) y la hipertensión arterial, y en pacientes que están en cuidados paliativos. CALIDAD DE LA EVIDENCIA: Los estudios que evaluaron la respiración consciente no presentan una buena calidad, es decir, que pueden presentar errores en su planteamiento y, por tanto, sus resultados deben ser tomados con precaución. RESULTADOS CLAVE: La respiración consciente podría considerarse una práctica segura y no se espera que aparezcan efectos adversos. Los resultados de los estudios localizados apuntan que podría reducir el estrés, la ansiedad y la depresión. En el entorno paliativo podría mejorar la angustia/malestar y los niveles de depresión y ansiedad, aunque no se han encontrado beneficios sobre síntomas como el dolor, la falta de aliento y las náuseas en estos pacientes. En cuanto a su uso en otras patologías, la evidencia parece señalar que podría mejorar la disnea y la hipertensión arterial. Estos resultados deben ser interpretados con suma cautela, ya que baja calidad metodológica global de la evidencia científica identificada no garantiza que sean extrapolables a la práctica clínica. CONCLUSIÓN FINAL: No existe evidencia confiable que apoye la eficacia de la respiración consciente para el tratamiento de las condiciones clínicas evaluadas.

NAME OF THE TECHNIQUE WITH HEALTH PURPOSES: Mindful breathing or mindful breath awareness. DEFINITION OF THE TECHNIQUE AND CLINICAL INDICATIONS: Mindful breathing or mindful breath awareness, consists of being fully present in the moment of breathing and feeling the effects of the breath on the body. This practice may reduce feelings of distress or stress for people who practice it, causing decreases in heart rate and respiratory rate at a physical level. This report has investigated the usefulness of this practice on stress, anxiety and depression, as well as in other pathologies such as dyspnea (shortness of breath), arterial hypertension, and palliative care patients. QUALITY OF THE EVIDENCE: The studies that have evaluated mindful breathing are generally of low quality, including failures in their approach, and therefore their results should be taken with cautio. KEY RESULTS: Mindful breathing could be considered as a safe practice and no adverse effects are expected. Results from studies suggest that mindful breathing may reduce stress, anxiety, and depression. In the palliative setting it may reduce distress, discomfort, depression, and anxiety levels, although no benefits have been found on symptoms such as pain, shortness of breath and nausea in these patients. In respect of its use in other conditions, the evidence seems to indicate that it could improve dyspnoea and arterial hypertension. These results should be interpreted with extreme caution, as the overall low methodological quality of the scientific evidence identified does not guarantee that they can be extrapolated to clinical practice. FINAL CONCLUSION: There is currently no reliable evidence to support the efficacy of mindful breathing for the treatment of the clinical conditions evaluated.

Respiratory muscle training and exercise ventilation while diving at altitude.

Introduction: Pre-dive altitude exposure may increase respiratory fatigue and subsequently augment exercise ventilation at depth. This study examined pre-dive altitude exposure and the efficacy of resistance respiratory muscle training (RMT) on respiratory fatigue while diving at altitude. Methods: Ten men (26±5 years; VO2peak: 39.8±3.3 mL• kg-1•min-1) performed three dives; one control (ground level) and two simulated altitude dives (3,658 m) to 17 msw, relative to ground level, before and after four weeks of resistance RMT. Subjects performed pulmonary function testing (e.g., inspiratory [PI] and expiratory [PE] pressure testing) pre- and post-RMT and during dive visits. During each dive, subjects exercised for 18 minutes at 55% VO2peak, and ventilation (VE), breathing frequency (ƒb,), tidal volume (VT) and rating of perceived exertion (RPE) were measured. Results: Pre-dive altitude exposure reduced PI before diving (p=0.03), but had no effect on exercise VE, ƒb, or VT at depth. At the end of the dive in the pre-RMT condition, RPE was lower (p=0.01) compared to control. RMT increased PI and PE (p<0.01). PE was reduced from baseline after diving at altitude (p<0.03) and this was abated after RMT. RMT did not improve VE or VT at depth, but decreased ƒb (p=0.01) and RPE (p=0.048) during the final minutes of exercise. Conclusion: Acute altitude exposure pre- and post-dive induces decrements in PI and PE before and after diving, but does not seem to influence ventilation at depth. RMT reduced ƒb and RPE during exercise at depth, and may be useful to reduce work of breathing and respiratory fatigue during dives at altitude.

Differences in Respiratory Muscle Responses to Hyperpnea or Loaded Breathing in COPD.

INTRODUCTION: We aimed to compare acute mechanical and metabolic responses of the diaphragm and rib cage inspiratory muscles during two different types of respiratory loading in patients with chronic obstructive pulmonary disease. METHODS: In 16 patients (age, 65 ± 13 yr; 56% male; forced expiratory volume in the first second, 60 ± 6%pred; maximum inspiratory pressure, 82 ± 5%pred), assessments of respiratory muscle EMG, esophageal pressure (Pes) and gastric pressures, breathing pattern, and noninvasive assessments of systemic (V˙O2, cardiac output, oxygen delivery and extraction) and respiratory muscle hemodynamic and oxygenation responses (blood flow index, oxygen delivery index, deoxyhemoglobin concentration, and tissues oxygen saturation [StiO2]), were performed during hyperpnea and loaded breathing. RESULTS: During hyperpnea, breathing frequency, minute ventilation, esophageal and diaphragm pressure-time product per minute, cardiac output, and V˙O2 were higher than during loaded breathing (P < 0.05). Average inspiratory Pes and transdiaphragmatic pressure per breath, scalene (SCA), sternocleidomastoid, and intercostal muscle activation were higher during loading breathing compared with hyperpnea (P < 0.05). Higher transdiaphragmatic pressure during loaded breathing compared with hyperpnea was mostly due to higher inspiratory Pes (P < 0.05). Diaphragm activation, inspiratory and expiratory gastric pressures, and rectus abdominis muscle activation did not differ between the two conditions (P > 0.05). SCA-blood flow index and oxygen delivery index were lower, and SCA-deoxyhemoglobin concentration was higher during loaded breathing compared with hyperpnea. Furthermore, SCA and intercostal muscle StiO2 were lower during loaded breathing compared with hyperpnea (P < 0.05). CONCLUSION: Greater inspiratory muscle effort during loaded breathing evoked larger rib cage and neck muscle activation compared with hyperpnea. In addition, lower SCA and intercostal muscle StiO2 during loaded breathing compared with hyperpnea indicates a mismatch between inspiratory muscle oxygen delivery and utilization induced by the former condition.

Assessment of Work of Breathing in Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease.

The assessment of the work of breathing (WOB) of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) is difficult, particularly when the patient first presents with acute hypercapnia and respiratory acidosis. Acute exacerbations of COPD patients are in significant respiratory distress and noninvasive measurements of WOB are easier for the patient to tolerate. Given the interest in using alternative therapies to noninvasive ventilation, such as high flow nasal oxygen therapy or extracorporeal carbon dioxide removal, understanding the physiological changes are key and this includes assessment of WOB. This narrative review considers the role of three different methods of assessing WOB in patients with acute exacerbations of COPD. Esophageal pressure is a very well validated measure of WOB, however the ability of patients with acute exacerbations of COPD to tolerate esophageal tubes is poor. Noninvasive alternative measurements include parasternal electromyography (EMG) and electrical impedance tomography (EIT). EMG is easily applied and is a well validated measure of neural drive but is more likely to be degraded by the electrical environment in intensive care or high dependency. EIT is less well validated as a tool for WOB in COPD but extremely well tolerated by patients. Each of the different methods assess WOB in a different way and have different advantages and disadvantages. For research into therapies treating acute exacerbations of COPD, combinations of EIT, EMG and esophageal pressure are likely to be better than only one of these.

Airway clearance techniques for patients with acute exacerbations of chronic obstructive pulmonary disease: Physical therapy practice in Sweden.

There is considerable global variability in clinical practice regarding the prescription of airway clearance techniques (ACTs) for patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Little is known about the physical therapy practice, and no international guidelines are available. The aim of this survey was to identify current physical therapy practice regarding ACT prescription for patients with AECOPD in Sweden. A cross-sectional, descriptive study was conducted via a Web-based questionnaire, sent to all (n = 70) hospitals that offer physical therapy service for patients with AECOPD in Sweden. Responses were received from 117 physical therapists (76%) across all sites. ACTs were prescribed for more than half of all patients with an AECOPD by 75% of physical therapists. The most frequently used ACTs were positive expiratory pressure (PEP) devices (90%), directed huffing (88%) and cough (71%). Most physical therapists (89%) perceived sputum clearance to be an important aspect of the overall management of patients with AECOPD. The main factors influencing choice of ACT were the 'degree of dyspnoea or work of breathing' and 'access to resources/equipment'. Physical therapists prescribe predominantly PEP-based ACTs for patients with AECOPD in Sweden. Several factors come into consideration that influences the choice of treatment technique.

Comparison of Diaphragmatic Stretch Technique and Manual Diaphragm Release Technique on Diaphragmatic Excursion in Chronic Obstructive Pulmonary Disease: A Randomized Crossover Trial.

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) impairs the function of the diaphragm by placing it at a mechanical disadvantage, shortening its operating length and changing the mechanical linkage between its various parts. This makes the diaphragm's contraction less effective in raising and expanding the lower rib cage, thereby increasing the work of breathing and reducing the functional capacity. AIM OF THE STUDY: To compare the effects of diaphragmatic stretch and manual diaphragm release technique on diaphragmatic excursion in patients with COPD. MATERIALS AND METHODS: This randomised crossover trial included 20 clinically stable patients with mild and moderate COPD classified according to the GOLD criteria. The patients were allocated to group A or group B by block randomization done by primary investigator. The information about the technique was concealed in a sealed opaque envelope and revealed to the patients only after allocation of groups. After taking the demographic data and baseline values of the outcome measures (diaphragm mobility by ultrasonography performed by an experienced radiologist and chest expansion by inch tape performed by the therapist), group A subjects underwent the diaphragmatic stretch technique and the group B subjects underwent the manual diaphragm release technique. Both the interventions were performed in 2 sets of 10 deep breaths with 1-minute interval between the sets. The two outcome variables were recorded immediately after the intervention. A wash-out period of 3 hours was maintained to neutralize the effect of given intervention. Later the patients of group A and group B were crossed over to the other group. RESULTS: In the diaphragmatic stretch technique, there was a statistically significant improvement in the diaphragmatic excursion before and after the treatment. On the right side, p=0.00 and p=0.003 in the midclavicular line and midaxillary line. On the left side, p=0.004 and p=0.312 in the midclavicular and midaxillary line. In manual diaphragm release technique, there was a statistically significant improvement before and after the treatment. On the right side, p=0.000 and p=0.000 in the midclavicular line and midaxillary line. On the left side, p=0.002 and p=0.000 in the midclavicular line and midaxillary line. There was no statistically significant difference in diaphragmatic excursion in the comparison of the postintervention values of both techniques. CONCLUSION: The diaphragmatic stretch technique and manual diaphragm release technique can be safely recommended for patients with clinically stable COPD to improve diaphragmatic excursion.

Respiratory mechanics and cerebral blood flow during heat-induced hyperventilation and its voluntary suppression in passively heated humans.

We investigated whether heat-induced hyperventilation can be voluntarily prevented, and, if so, how this modulates respiratory mechanics and cerebral blood flow in resting heated humans. In two separate trials, 10 healthy men were passively heated using lower body hot-water immersion and a water-perfused garment covering their upper body (both 41°C) until esophageal temperature (Tes ) reached 39°C or volitional termination. In each trial, participants breathed normally (normal-breathing) or voluntarily controlled minute ventilation (VE ) at a level equivalent to that observed after 5 min of heating (controlled-breathing). Respiratory gases, middle cerebral artery blood velocity (MCAV), work of breathing, and end-expiratory and inspiratory lung volumes were measured. During normal-breathing, VE increased as Tes rose above 38.0 ± 0.3°C, whereas controlled-breathing diminished the increase in VE (VE at Tes  = 38.6°C: 25.6 ± 5.9 and 11.9 ± 1.3 L min-1 during normal- and controlled-breathing, respectively, P < 0.001). During normal-breathing, end-tidal CO2 pressure and MCAV decreased with rising Tes , but controlled-breathing diminished these reductions (at Tes  = 38.6°C, 24.7 ± 5.0 vs. 39.5 ± 2.8 mmHg; 44.9 ± 5.9 vs. 60.2 ± 6.3 cm sec-1 , both P < 0.001). The work of breathing correlated positively with changes in VE (P < 0.001) and was lower during controlled- than normal-breathing (16.1 ± 12.6 and 59.4 ± 49.5 J min-1 , respectively, at heating termination, P = 0.013). End-expiratory and inspiratory lung volumes did not differ between trials (P = 0.25 and 0.71, respectively). These results suggest that during passive heating at rest, heat-induced hyperventilation increases the work of breathing without affecting end-expiratory lung volume, and that voluntary control of breathing can nearly abolish this hyperventilation, thereby diminishing hypocapnia, cerebral hypoperfusion, and increased work of breathing.

Effects of Sprint-Interval and Endurance Respiratory Muscle Training Regimens.

INTRODUCTION: Recently a novel, time-saving respiratory muscle sprint-interval training (RMSIT) was developed. To test the extent to which RMSIT improves respiratory muscle performance compared with a conventional respiratory muscle endurance training (RMET), a novel incremental respiratory muscle test (IncRMT), loading inspiratory and expiratory muscles, was designed to assess performance changes associated with respiratory muscle training (RMT). METHODS: Healthy, moderately trained males and females (age: 26 ± 5 yr, V˙O2peak: 47 ± 12 mL·min·kg) were randomized and balanced to three groups (RMSIT 5m/5f; RMET 6m/6f; PLAT 5m/6f). Lung function, respiratory muscle strength, and IncRMT performance were tested before and after 1 month of RMT. During the IncRMT, muscle activity and muscle deoxygenation were assessed via surface EMG and near-infrared spectroscopy of sternocleidomastoid (STERNO), intercostal (INTER), and abdominal (ABDO) muscles. RESULTS: Two-way ANOVA revealed a main effect of training for increased maximal voluntary ventilation (P = 0.001) and maximal inspiratory pressure (P = 0.017). Both RMT groups increased work of breathing during training sessions to the same extent (RMSIT: +17.4 ± 8.9 kJ; RMET: +26.2 ± 16.1 kJ; P = 0.143) with a larger increase in average mouth pressure in RMSIT (RMSIT: +20.0 ± 15.0 cm H2O; RMET: +3.3 ± 1.5 cm H2O; P = 0.001). After training, IncRMT duration increased in both RMT groups compared with PLAT (RMSIT: +5.6 ± 2.1 min, P = 0.0006 vs PLAT; RMET: +3.8 ± 4.2 min, P = 0.020 vs PLAT). At similar work, only INTER activity during inspiration increased after RMET. Higher performance after RMSIT was associated with higher activity in STERNO and ABDO, but after RMET, STERNO, INTER, and ABDO showed higher activity. CONCLUSION: One month of RMSIT and RMET shows similar improvements in respiratory muscle performance despite different duration of training sessions. Also, muscular adaptations might differ.

Effect of Breathing Exercise Using Panflutes on the Postoperative Compliance, Pulmonary Infections and Life Satisfaction in Elderly Patients Undergoing Spinal Surgery

PURPOSE: The purpose of this study was to examine the effects of breathing exercises performed using panflutes in elderly patients undergoing spinal surgery. METHODS: The study design was a nonequivalent control group non-synchronized pre-post test. The study included 24 patients in both the experimental group and the control group. The experimental group completed a daily breathing exercise regimen using panflutes for 30minutes after meals, whereas the control group was provided standard preoperative education, including breathing exercises using incentive spirometers. After the exercise regimen, breathing exercise compliance, pulmonary infections, and life satisfaction were measured in both groups, and the data were analyzed using the SPSS/WIN program. RESULTS: The compliance rate of breathing exercises was significantly higher in the experimental group. The experimental group presented no pulmonary infections in the later period, whereas the control group presented higher pulmonary infection rates in the same period. In addition, the life satisfaction score in the experimental group significantly increased. CONCLUSION: The breathing exercise program using panflutes for elderly patients undergoing spinal surgery enhanced their breathing exercise compliance and their daily life satisfaction in addition to reducing their pulmonary infection rates.

Fisioterapia no paciente com asma: intervenção baseada em evidências / Physiotherapy in asthma patients: evidence-based intervention

As intervenções fisioterapêuticas destacam-se como tratamento não farmacológico e são coadjuvantes no tratamento da asma. O tratamento fisioterapêutico só deve ser iniciado quando o indivíduo estiver com a medicação ajustada para sua condição e em acompanhamento médico regular. Como a asma é uma doença crônica com episódios recorrentes de sibilância, tosse e dispneia, ocorre aumento do trabalho respiratório e da percepção do esforço, podendo levar a alterações da mecânica respiratória, função muscular respiratória e do descondicionamento físico. Os objetivos da fisioterapia são: reduzir o desconforto respiratório e a dispneia, melhorar a mecânica respiratória, melhorar a força muscular respiratória nos casos de fraqueza desta musculatura, melhorar o condicionamento cardiorrespiratório, promover higiene brônquica, quando necessária, e melhorar a qualidade de vida. Estudos prévios investigaram os efeitos dos exercícios respiratórios, do treinamento muscular respiratório (TMR), da reabilitação pulmonar (RP) e das técnicas de higiene brônquica em pacientes asmáticos. Não há evidências de que os exercícios respiratórios melhorem a função pulmonar, embora reduzam os sintomas e a medicação de resgate e melhorem a qualidade de vida. O TMR diminui a dispneia, aumenta a força muscular inspiratória e melhora a capacidade de exercício. O treinamento físico, que é o principal componente da RP, leva à melhora dos sintomas respiratórios, da capacidade funcional e qualidade de vida. Por fim, não há evidências científicas que suportem a realização de técnicas manuais de higiene brônquica. No entanto, o oscilador oral de alta frequência pode ser uma estratégia para eliminar secreção de adultos e crianças na vigência de infecção pulmonar.

Respiratory physiotherapy stands out as a nonpharmacological approach and is an adjuvant intervention in the treatment of asthma. Physiotherapy should only be initiated when the medication is adjusted to the patient's condition and when the patient is under regular medical follow-up. Asthma is a chronic disease with recurrent episodes of wheezing, cough, and dyspnea, resulting in increased respiratory workload and perceived exertion and potentially leading to changes in respiratory mechanics, respiratory muscle function, and physical deconditioning. The objectives of respiratory physiotherapy are: to reduce respiratory distress and dyspnea, to improve respiratory mechanics and respiratory muscle strength (in cases of muscle weakness), to improve cardiopulmonary conditioning, to promote bronchial hygiene when necessary, and to improve quality of life. Previous studies have investigated the effects of breathing exercises, respiratory muscle training (RMT), pulmonary rehabilitation (PR), and bronchial hygiene techniques in patients with asthma. There is no evidence that breathing exercises can improve lung function, even though they reduce symptoms and the use of rescue medication and improve quality of life. RMT reduces dyspnea, increases inspiratory muscle strength, and improves exercise capacity. Physical training, the main component of PR, leads to improvement of respiratory symptoms, functional capacity, and quality of life. Finally, there is no scientific evidence supporting the use of manual bronchial hygiene techniques. Nevertheless, the use of oral high-frequency oscillators could be a strategy for mucus clearance in adults and children with pulmonary infection.

The Effects of Prone with Respect to Supine Position on Stress Relaxation, Respiratory Mechanics, and the Work of Breathing Measured by the End-Inflation Occlusion Method in the Rat.

PURPOSE: The working hypothesis is that the prone position with respect to supine may change the geometric configuration of the lungs inside the chest wall, thus their reciprocal mechanical interactions, leading to possible effects on stress relaxation phenomena and respiratory mechanics. METHOD: The effects of changing body posture from supine to prone on respiratory system mechanics, particularly on stress relaxation, were investigated in the rat by the end-inflation occlusion method. RESULTS: In the prone with respect to supine position, an increment of the frictional resistance of the airway (from 0.13 ± 0.01 to 0.19 ± 0.02 cm H2O/l sec(-1), p < 0.05) and a decrement of the stress relaxation-linked pressure dissipation (from 0.51 ± 0.05 to 0.45 ± 0.05 cm H2O/l sec(-1), p < 0.01) were found. Respiratory system elastance and total resistive pressure dissipation did not change significantly. Accordingly, a significant increase of the frictional "ohmic" mechanical inspiratory work of breathing and a decrease of the visco-elastic work of inspiration were demonstrated, while no significant changes occurred for the total mechanical work of breathing and its total resistive and elastic components. CONCLUSION: It is concluded that postural changes affect the visco-elastic characteristics of the respiratory system and the related stress relaxation phenomena by influencing the disposition and relation of the lungs inside the chest wall and their relative geometrical configuration, and the interaction phenomena of the constitutive parenchymal structures, i.e., elastin and collagen fibers. Since the prone position resulted in no serious or disadvantageous respiratory system mechanical derangement, it is suggested it may be usefully applied in nursing or for therapeutic goals.

Positive expiratory pressure - Common clinical applications and physiological effects.

Breathing out against resistance, in order to achieve positive expiratory pressure (PEP), is applied by many patient groups. Pursed lips breathing and a variety of devices can be used to create the resistance giving the increased expiratory pressure. Effects on pulmonary outcomes have been discussed in several publications, but the expected underlying physiology of the effect is seldom discussed. The aim of this article is to describe the purpose, performance, clinical application and underlying physiology of PEP when it is used to increase lung volumes, decrease hyperinflation or improve airway clearance. In clinical practice, the instruction how to use an expiratory resistance is of major importance since it varies. Different breathing patterns during PEP increase or reduce expiratory flow, result in movement of EPP centrally or peripherally and can increase or decrease lung volume. It is therefore necessary to give the right instructions to obtain the desired effects. As the different PEP techniques are being used by diverse patient groups it is not possible to give standard instructions. Based on the information given in this article the instructions have to be adjusted to give the optimal effect. There is no consensus regarding optimal treatment frequency and number of cycles included in each treatment session and must also be individualized. In future research, more precise descriptions are needed about physiological aims and specific instructions of how the treatments have been performed to assure as good treatment quality as possible and to be able to evaluate and compare treatment effects.

Acute Effects of a Respiratory Sprint-Interval Session on Muscle Contractility.

INTRODUCTION: Respiratory muscle training has been shown to improve physical performance in healthy individuals and patients. One training modality for both inspiratory and expiratory muscles is respiratory muscle endurance training (RMET), which consists of normocapnic hyperpnea at constant ventilation for 30 min. Here, a new training regimen, respiratory muscle sprint-interval training (RMSIT), is introduced and tested for its potential to fatigue respiratory muscles. In addition, effects of both modalities on airway properties are investigated. METHODS: In 12 healthy subjects (six men and six women; 24 ± 3 yr; forced expiratory volume in 1 s, 115% ± 10%), changes in inspiratory transdiaphragmatic twitch pressure (Pdi,tw) and expiratory gastric twitch pressure (Pga,tw) were assessed during cervical magnetic stimulation or thoracic magnetic stimulation before and after a single bout of RMET and RMSIT. At similar time points, mechanical airway properties were assessed by impulse oscillometry. RMET was performed for 30 min at 60% of maximal voluntary ventilation, with constant tidal volume and breathing frequency. RMSIT consisted of six 30-s respiratory sprints (with 2-min breaks in between) at constant tidal volume, with the greatest possible breathing frequency and added resistance. RESULTS: Pdi,tw and Pga,tw decreased significantly after RMET (-17.7% ± 9.0% and -22.4% ± 18.5%; P < 0.01) and RMSIT (-18.1% ± 12.8% and -21.2% ± 13.1%; P < 0.01), and changes did not differ between training modalities (P = 0.50 and P = 0.12), suggesting similar levels of fatigue. Work of breathing per minute was 2.4 ± 0.8-fold greater in RMSIT than in RMET, whereas total work of breathing was substantially smaller in RMSIT (3.4 ± 0.8 kJ) than in RMET (15.0 ± 0.42 kJ). No subject showed clinically relevant changes in mechanical airway properties. CONCLUSIONS: Despite different work history, RMSIT appears to place a metabolic load on respiratory muscles similarly to RMET and could therefore be considered a time-saving and safe training alternative.

The effects of inspiratory muscle training in older adults.

PURPOSE: Declining inspiratory muscle function and structure and systemic low-level inflammation and oxidative stress may contribute to morbidity and mortality during normal ageing. Therefore, we examined the effects of inspiratory muscle training (IMT) in older adults on inspiratory muscle function and structure and systemic inflammation and oxidative stress, and reexamined the reported positive effects of IMT on respiratory muscle strength, inspiratory muscle endurance, spirometry, exercise performance, physical activity levels (PAL), and quality of life (QoL). METHODS: Thirty-four healthy older adults (68 ± 3 yr) with normal spirometry, respiratory muscle strength, and physical fitness were divided equally into a pressure-threshold IMT or sham-hypoxic placebo group. Before and after an 8-wk intervention, measurements were taken for dynamic inspiratory muscle function and inspiratory muscle endurance using a weighted plunger pressure-threshold loading device; diaphragm thickness by using B-mode ultrasonography; plasma cytokine concentrations by using immunoassays; DNA damage levels in peripheral blood mononuclear cells by using comet assays; spirometry, maximal mouth pressures, and exercise performance by using a 6-min walk test; PAL by using a questionnaire and accelerometry; and QoL using a questionnaire. RESULTS: Compared with placebo, IMT increased maximal inspiratory pressure (+34% ± 43%, P = 0.008), diaphragm thickness at residual volume (+38% ± 39%, P = 0.03), and peak inspiratory flow (+35% ± 42%, P = 0.049) but did not change other spirometry measures, plasma cytokine concentrations, DNA damage levels in peripheral blood mononuclear cells, dynamic inspiratory muscle function, inspiratory muscle endurance, exercise performance, PAL, or QoL. CONCLUSION: These novel data indicate that in healthy older adults, IMT elicits some positive changes in inspiratory muscle function and structure but neither attenuates systemic inflammation and oxidative stress nor improves exercise performance, PAL, or QoL.

A review of recent findings about stress-relaxation in the respiratory system tissues.

This article reviews the state of the art about an unclear physiological phenomenon interesting respiratory system tissues, i.e., stress-relaxation. Due to their visco-elastic properties, the tissues do not maintain constant stress under constant deformation. Rather, the stress slowly relaxes and falls to a lower value. The exact molecular basis of this complex visco-elastic behavior is not well defined, but it has been suggested that it may be generated because of the anisotropic mechanical properties of elastin and collagen fibers in the alveolar septa and their interaction phenomena, such as reciprocal sliding, also in relation to interstitial liquid movements. The effects on stress-relaxation of various biochemical and physical factors are reviewed, including the consequences of body temperature variations, respiratory system inflammations and hyperbaric oxygen exposure, endocrinal factors, circulating blood volume variations, changes in inflation volume and/or flow, changes in intra-abdominal pressure because of pneumoperitoneum or Trendelenburg position. The effects of these factors on stress-relaxation have practical consequences because, depending on visco-elastic pressure amount which is requested to inflate the respiratory system in different conditions, respiratory muscles have to produce different values of inspiratory pressure during spontaneous breathing. High inspiratory pressure values might increase the risk of respiratory failure development on mechanical basis.

Physiotherapy intervention for preventing the respiratory muscle deterioration in institutionalized older women with functional impairment.

INTRODUCTION: In elderly seniors (>80 years), respiratory function may be compromised when, in addition to the presence of comorbidity and loss of mobility, there is also reduced respiratory muscle (RM) strength. The literature has shown that RM training could be an effective method to improve RM function and prevent clinical deterioration, particularly in population with RM weakness. The main purpose of this paper was to assess the effectiveness of RM training on the respiratory muscle strength and endurance of institutionalized elderly women with functional impairment. METHOD: Fifty-four residents (mean=85 years, SD=6.7) were randomly assigned to either a control (n=27) or training (n=27) group. A supervised training program was developed with Threshold(®)IMT, five times per week for 6-weeks. The main variables of the intervention were: maximum inspiratory pressure (PI(max)), maximum expiratory pressure (PE(max)) and maximal voluntary ventilation (MVV), all of which were measured at weeks 0, 4, 7 and 10. RESULTS: Statistical analysis revealed no significant differences in PI(max) (F(3,114)=1.04, p=0.368, R(2)=0.027), PE(max) (F(3,114)=1.86, p=0.14, R(2)=0.047) and MVV (F(3,114)=1.74, p=0.162, R(2)=0.044) between the two groups after the intervention. However, the workload significantly improved with the training sessions (F(5,100)=72.031, p<0.001, R(2)=0.791). CONCLUSION: In a 6-week interval-based training program, the threshold loading device does not significantly improve parameters related to RM strength and endurance of the study population.

Effects of inspiratory muscle training on dynamic hyperinflation in patients with COPD.

Dynamic hyperinflation has important clinical consequences in patients with chronic obstructive pulmonary disease (COPD). Given that most of these patients have respiratory and peripheral muscle weakness, dyspnea and functional exercise capacity may improve as a result of inspiratory muscle training (IMT). The aim of the study was to analyze the effects of IMT on exercise capacity, dyspnea, and inspiratory fraction (IF) during exercise in patients with COPD. Daily inspiratory muscle strength and endurance training was performed for 8 weeks in 10 patients with COPD GOLD II and III. Ten patients with COPD II and III served as a control group. Maximal inspiratory pressure (Pimax) and endurance time during resistive breathing maneuvers (tlim) served as parameter for inspiratory muscle capacity. Before and after training, the patients performed an incremental symptom limited exercise test to maximum and a constant load test on a cycle ergometer at 75% of the peak work rate obtained in the pretraining incremental test. ET was defined as the duration of loaded pedaling. Following IMT, there was a statistically significant increase in inspiratory muscle performance of the Pimax from 7.75 ± 0.47 to 9.15 ± 0.73 kPa (P < 0.01) and of tlim from 348 ± 54 to 467 ± 58 seconds (P < 0.01). A significant increase in IF, indicating decreased dynamic hyperinflation, was observed during both exercise tests. Further, the ratio of breathing frequency to minute ventilation (bf/V'(E)) decreased significantly, indicating an improved breathing pattern. A significant decrease in perception of dyspnea was also measured. Peak work rate during the incremental cycle ergometer test remained constant, while ET during the constant load test increased significantly from 597.1 ± 80.8 seconds at baseline to 733.6 ± 74.3 seconds (P < 0.01). No significant changes during either exercise tests were measured in the control group. The present study found that in patients with COPD, IMT results in improvement in performance, exercise capacity, sensation of dyspnea, and improvement in the IF prognostic factor.

Flow resistance, work of breathing of humidifiers, and endotracheal tubes in the hyperbaric chamber.

Humidification of inspired gas is critical in ventilated patients, usually achieved by heat and moisture exchange devices (HMEs). HME and the endotracheal tube (ETT) add airflow resistance. Ventilated patients are sometimes treated in hyperbaric chambers. Increased gas density may increase total airway resistance, peak pressures (PPs), and mechanical work of breathing (WOB). We tested the added WOB imposed by HMEs and various sizes of ETT under hyperbaric conditions. We mechanically ventilated 4 types of HMEs and 3 ETTs at 6 minute ventilation volumes (7-19.5 L/min) in a hyperbaric chamber at pressures of 1 to 6 atmospheres absolute (ATA). Peak pressure increased with increasing chamber pressure with an HME alone, from 2 cm H2O at 1 ATA to 6 cm H(2)O at 6 ATA. Work of breathing was low at 1 ATA (0.2 J/L) and increased to 1.2 J/L at 6 ATA at minute ventilation = 19.5 L/min. Connecting the HME to an ETT increased PP as a function of peak flow and chamber pressure. Reduction of the ETT diameter (9 > 8 > 7.5 mm) and increase in chamber pressure increased the PP up to 27.7 cm H2O, resistance to 33.2 cmH2O*s/L, and WOB to 3.76 J/L at 6 ATA with a 7.5-mm EET. These are much greater than the usually accepted critical peak pressures of 25 cm H2O and WOB of 1.5 to 2.0 J/L. Endotracheal tubes less than 8 mm produce significant added WOB and airway pressure swings under hyperbaric conditions. The hyperbaric critical care clinician is advised to use the largest possible ETT. The tested HMEs add negligible resistance and WOB in the chamber.

Respiratory muscle training reduces the work of breathing at depth.

Resistance respiratory muscle training (RRMT) increases respiratory muscle and swimming performance at depths down to 17 msw. It is unknown if RRMT improves swimming performance at greater depths and if the improvements are associated with a reduced work of breathing (WOB), altered respiratory mechanics and/or improved respiratory muscle performance. Eight male subjects (30.3 +/- 6.0 years) were tested swimming underwater in a hyperbaric chamber at 37 m of depth against a pre-determined load (70% VO(2)) until exhausted. End expiratory lung volume (EELV) was determined by subtracting inspiratory capacity from total lung capacity throughout the swims. The mechanical WOB on the lung was calculated as the integrated product of the transpulmonary pressure and ventilatory flow. Maximal expiratory (P EMAX) and inspiratory pressures (P IMAX) were measured pre- and post-RRMT. RRMT was performed every 30 s against spring loaded inspiratory and expiratory valves 30 min/day, 5 days/week, for 4 weeks. RRMT increased P (IMAX) and P (EMAX) by 40% (110 +/- 11 cmH2O (SD) vs. 155 +/- 22, p < 0.001) and 30% (148 +/- 33 cmH2O vs. 192 +/- 49, p < 0.001), respectively, respiratory endurance by 75% (19.7 +/- 15.4 min vs. 34.4 +/- 27.3, p = 0.010), and swimming endurance by 87% (26.4 +/- 9.7 min vs. 49.4 +/- 21.6, p = 0.004). The longer swimming time was associated with reduced V(E) and V(A) (p < 0.001), f(b) (p < 0.001), V(CO(2)) (p < 0.001) and WOB (p < 0.001). There were no changes in EELV post-RRMT. These results suggest the improved exercise performance post-RRMT was associated with stronger respiratory muscles, a decreased f b, and a reduced WOB.