Reduced Inspiratory Muscle Endurance Following Successful Weaning From Prolonged Mechanical Ventilation

Effects of proprioceptive neuromuscular facilitation combined with threshold inspiratory muscle training on respiratory function in neurocritical patients with weaning failure: a randomized controlled trial

The purpose of this study was to determine the effects of combining proprioceptive neuromuscular facilitation (PNF) with threshold inspiratory muscle training (TIMT), compared with TIMT alone, on respiratory function in neurocritical patients who experienced a weaning failure. Forty-seven participants (mostly after a stroke), were randomly divided into the experimental group ( n  = 24) and the control group ( n  = 23). The control group received usual care and TIMT, whereas the experimental group, in addition, underwent four 90-s periods of manual PNF. Both groups performed training in the ICU twice a day for 5 consecutive days. The main outcome measures included maximum inspiratory pressure, diaphragmatic excursions, diaphragm thickening fraction, oxygenation index, and forced expiratory volume in 1 s/forced vital capacity. The results showed a significant group-by-time interaction effect for maximum inspiratory pressure [ F (1, 45) = 17.84, η2  = 0.328, P  < 0.001] and oxygenation index [ F [1, 45) = 5.58, η2  = 0.11, P  = 0.023]. When compared with the control group, the experimental group showed overall significantly higher maximum inspiratory pressure [mean difference = 4.37 cm H 2 O, 95% confidence interval (CI) 0.25-8.50, P  = 0.038]. No other significant group differences were found. Combining PNF with TIMT may improve respiratory function in neurocritical patients with weaning failure. This combination approach may increase the likelihood of survival of neurocritical patients in the ICU.

Mechanical ventilation in dogs and cats with tick paralysis

Respiratory failure from tick paralysis (TP) is an important cause of mortality in cats and dogs in Australia, occurring from a combination of respiratory muscle paralysis, upper respiratory tract obstruction and pulmonary disease. Patients may require positive-pressure ventilation in management of any combination of hypoxemia, hypoventilation or respiratory fatigue, but may also require airway management due to laryngeal paralysis. No single ventilation strategy is recommended due to the heterogenous disease presentations. Lung protective ventilation should be used in patients with pulmonary disease. Due to local and systemic effects of TP, patients are at higher risk of complications such as aspiration pneumonia and corneal ulceration and may have additional intravenous fluid and nutritional considerations. Treatment with hyperimmune serum is associated with improved outcomes. Prognosis is considered good with documented survival to discharge (STD) of 52.6-77% for animals with TP ventilated with lung disease and 90.5% for animals without lung disease. Median reported duration of ventilation for TP ranges from 23 to 48 h (range 3 h-10 days). The severity of individual neuromuscular signs and the presence of associated conditions such as aspiration pneumonia and laryngeal paralysis may necessitate longer periods of mechanical ventilation. This review aims to summarize the current recommendations regarding indications, management and prognosis of cats and dogs undergoing MV for TP and to identify areas for future research.

Does mechanical threshold inspiratory muscle training promote recovery and improve outcomes in patients who are ventilator-dependent in the intensive care unit? The IMPROVE randomised trial

BACKGROUND

In patients who are ventilator-dependent in the intensive care unit, inspiratory muscle training may improve inspiratory muscle strength and accelerate liberation from the ventilator, but optimal training parameters are yet to be established, and little is known about the impact of inspiratory muscle training on quality of life or dyspnoea. Thus, we sought to ascertain whether inspiratory muscle training, commenced while ventilator-dependent, would improve outcomes for patients invasively ventilated for 7 days or longer.

METHODS

In this randomised trial with assessor blinding and intention-to-treat analysis, 70 participants (mechanically ventilated ≥7 days) were randomised to receive once-daily supervised high-intensity inspiratory muscle training with a mechanical threshold device in addition to usual care or to receive usual care (control). Primary outcomes were inspiratory muscle strength (maximum inspiratory pressure % predicted) and endurance (fatigue resistance index) at ventilator liberation and 1 week later. Secondary outcomes included quality of life (SF-36v2, EQ-5D), dyspnoea, physical function, duration of ventilation, and in-hospital mortality.

RESULTS

Thirty-three participants were randomly allocated to the training group, and 37 to the control group. There were no statistically significant differences in strength (maximum inspiratory pressure) (95% confidence interval [CI]: -7.4 to 14.0) or endurance (fatigue resistance index) (95% CI: -0.003 to 0.436). Quality of life improved significantly more in the training group than in the control group (EQ-5D: 17.2; 95% CI: 1.3-33.0) (SF-36-PCS: 6.97; 95% CI: 1.96-12.00). Only the training group demonstrated significant reductions in dyspnoea (-1.5 at rest, -1.9 during exercise). There were no between-group differences in duration of ventilation or other measures. In-hospital mortality was higher in the control group than in the training group (9 vs 4, 24% vs 12%, p = 0.23).

CONCLUSIONS

In patients who are ventilator-dependent, mechanical threshold loading inspiratory muscle training improves quality of life and dyspnoea, even in the absence of strength improvements or acceleration of ventilator liberation.

Efficacy of a rehabilitation protocol on pulmonary and respiratory muscle function and ultrasound evaluation of diaphragm and quadriceps femoris in patients with post-COVID-19 syndrome: a series of cases

This study assessed the efficacy of a pulmonary rehabilitation (PR) on pulmonary and respiratory muscle function and thickness of quadriceps femoris and diaphragm of patients with post-COVID-19 syndrome. This series of cases followed nine patients who performed PR twice a week for six weeks. Patients received the following PR program: lung expansion therapy; respiratory muscle training; upper limb strength exercises; aerobic exercises on a treadmill. After the program, we observed increased peak expiratory flow (26.03%), forced vital capacity (FVC) (7.14%), forced expiratory volume in the first second (FEV1) (9.55%), and ratio between FEV1/FVC (6.19%). All parameters of respiratory muscle strength and endurance were improved. Diaphragmatic thickening fraction and thickness of quadriceps femoris also improved, whereas echo intensity of quadriceps reduced. Thus, RP protocol improved pulmonary function, respiratory muscle strength and endurance, and thickness of diaphragm and quadriceps femoris, and reduced echo intensity of quadriceps in patients with post-COVID-19 syndrome.

Impact of peripheral muscle strength on prognosis after extubation and functional outcomes in critically ill patients: a feasibility study

The influence of peripheral muscle strength on prognosis after extubation and subsequent functional outcomes is not evident. The objectives of this study were to determine (1) whether peripheral muscle strength can be used as a predictor for patients' prognoses after extubation, and (2) whether the peripheral muscle strength before extubation is correlated with patients' subsequent ambulation ability and in-hospital mortality. This study was a prospective observational cohort study. A hand-held dynamometer was used for evaluated the muscle strength of the biceps and quadriceps right before extubation. Besides, after the patients had been transferred from the ICU to the general ward, a 2-minute walk test was performed. A total of 52 patients were enrolled in this study, and the rate of extubation failure was 15%. The muscle strength of the quadriceps was significantly correlated with the prognosis after extubation, 48% of the patients were able to ambulate after being transferred to the general ward. The overall mortality rate was 11%, and there was a significant correlation between the biceps muscle strength and in-hospital mortality. Peripheral muscle strength may serve as an important predictor of a patients' prognoses after extubation. Poor peripheral muscle strength is indicative of not only a higher risk of re-intubation but also higher in-hospital mortality and poorer functional outcomes.Trial registration: ISRCTN16370134. Registered 30 May 2019, prospectively registered. https://www.isrctn.com/ISRCTN16370134 .

Ventilatory failure in a cat following radical chest wall resection for feline injection site sarcoma

Case summary

A 12-year-old spayed female domestic shorthair cat presented for chest wall resection and radiation therapy following incomplete surgical excision of a feline injection site sarcoma. A CT scan for surgical planning was performed under general anesthesia and showed extensive tumor infiltration of the soft tissues of the right thorax. The cat recovered uneventfully from this anesthetic event. Nineteen days later, the patient was reanesthetized for forequarter amputation plus radical chest wall resection, including ribs 3–8 and all associated soft tissues plus adjacent spinous processes. Postoperatively, the patient developed acute respiratory failure secondary to hypoventilation. The cat was mechanically ventilated for 12 h prior to being successfully weaned from the ventilator. However, the improvement was transient and mechanical ventilation was reinitiated 6 h later owing to respiratory fatigue. On the second day, the cat developed unexplained central nervous system signs and was euthanized.

Relevance and novel information

To our knowledge, this is the first case report to describe ventilatory failure secondary to radical chest wall resection in a cat. Hypoventilation with subsequent need for mechanical ventilation is a potential complication that should be considered during preoperative planning in patients requiring extensive chest wall resections.

Mechanical ventilation strategy for pulmonary rehabilitation based on patient-ventilator interaction

Mechanical ventilation is an effective medical means in the treatment of patients with critically ill, COVID-19 and other pulmonary diseases. During the mechanical ventilation and the weaning process, the conduct of pulmonary rehabilitation is essential for the patients to improve the spontaneous breathing ability and to avoid the weakness of respiratory muscles and other pulmonary functional trauma. However, inappropriate mechanical ventilation strategies for pulmonary rehabilitation often result in weaning difficulties and other ventilator complications. In this article, the mechanical ventilation strategies for pulmonary rehabilitation are studied based on the analysis of patient-ventilator interaction. A pneumatic model of the mechanical ventilation system is established to determine the mathematical relationship among the pressure, the volumetric flow, and the tidal volume. Each ventilation cycle is divided into four phases according to the different respiratory characteristics of patients, namely, the triggering phase, the inhalation phase, the switching phase, and the exhalation phase. The control parameters of the ventilator are adjusted by analyzing the interaction between the patient and the ventilator at different phases. A novel fuzzy control method of the ventilator support pressure is proposed in the pressure support ventilation mode. According to the fuzzy rules in this research, the plateau pressure can be obtained by the trigger sensitivity and the patient's inspiratory effort. An experiment prototype of the ventilator is established to verify the accuracy of the pneumatic model and the validity of the mechanical ventilation strategies proposed in this article. In addition, through the discussion of the patient-ventilator asynchrony, the strategies for mechanical ventilation can be adjusted accordingly. The results of this research are meaningful for the clinical operation of mechanical ventilation. Besides, these results provide a theoretical basis for the future research on the intelligent control of ventilator and the automation of weaning process.

Home-based exercise can be beneficial for counteracting sedentary behavior and physical inactivity during the COVID-19 pandemic in older adults

The novel pandemic called coronavirus disease 2019 (COVID-19), as a global public health emergency, seems to be having a major impact on physical activity (PA) behaviors. Older adults are at high risk of death from the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2). Health authorities around the world have been implementing preventive health measures, including quarantine and self-isolation, to mitigate the COVID-19 outbreak. This period is characterized by the cessation of outdoor exercising. During this period of lockdown, PA has been one of the rare reasons for going out in some countries. To avoid the harmful effects of periods of exercise cessation, PA could be prescribed to older adults, which is of great importance for breaking their sedentary lifestyle and improving their immunity. The present review discusses the potential impacts of the COVID-19 pandemic on sedentary behavior and physical inactivity in older adults. The importance of performing PA to reduce the harmful effects of the COVID-19 pandemic is discussed, and useful recommendations on home-based exercise for the older adults to maintain their level of independence, physical and mental health as well as their well-being are provided.

The combination of inspiratory muscle training and high-flow nasal cannula oxygen therapy for promoting weaning outcomes in difficult-to-wean patients: protocol for a randomised controlled trial

Background

According to the literature, 20-30% of intubated patients are difficult to wean off mechanical ventilation and have a prolonged intensive care unit (ICU) stay with detrimental effects on muscle strength, functional ability and quality of life. Inspiratory muscle training (IMT) via a threshold device has been proposed as an effective exercise for minimising the effects of mechanical ventilation on respiratory muscles of critically ill patients with prolonged weaning. In addition, high-flow nasal cannula (HFNC) oxygen has been proved to provide efficient support for both high- and low-risk patients after extubation, thus preventing re-intubation.

Material and methods

A randomised controlled trial was designed to assess the efficacy of combining IMT and HFNC as therapeutic strategies for patients with high risk for weaning failure. Once patients with prognostic factors of difficult weaning are awake, ventilated with support settings and cooperative, they will be randomised to one of the two following study groups: intervention group (IMT and HFNC) and control group (IMT and Venturi mask). IMT will start as soon as possible. Each allocated oxygen delivery device will be applied immediately after extubation. IMT intervention will continue until patients' discharge from ICU. The primary outcome is the rate of weaning failure. Secondary outcomes are maximal inspiratory and expiratory strength, endurance of respiratory muscles, global muscle strength, functional ability and quality of life along with duration of ventilation (days) and ICU and hospital length of stay.

Conclusion

The present study could significantly contribute to knowledge of how best to treat patients with difficult weaning and high risk of re-intubation.

Effects of Inspiratory Muscle Training and Early Mobilization on Weaning of Mechanical Ventilation: A Systematic Review and Network Meta-analysis

OBJECTIVE

To compare the effectiveness and rank order of physical therapy interventions, including conventional physical therapy (CPT), inspiratory muscle training (IMT), and early mobilization (EM) on mechanical ventilation (MV) duration and weaning duration.

DATA SOURCES

PubMed, The Cochrane Library, Scopus, and CINAHL complete electronic databases were searched through August 2019.

STUDY SELECTION

Randomized controlled trials (RCTs) investigating the effect of IMT, EM, or CPT on MV duration and the weaning duration in patients with MV were included. Studies that were determined to meet the eligibility criteria by 2 independent authors were included. A total of 6498 relevant studies were identified in the search, and 18 RCTs (934 participants) were included in the final analysis.

DATA EXTRACTION

Data were extracted independently by 2 authors and assessed the study quality by the Cochrane risk-of-bias tool. The primary outcomes were MV duration and weaning duration.

DATA SYNTHESIS

Various interventions of physical therapy were identified in the eligible studies, including IMT, IMT+CPT, EM, EM+CPT, and CPT. The data analysis demonstrated that compared with CPT, IMT+CPT significantly reduced the weaning duration (mean difference; 95% confidence interval) (-2.60; -4.76 to -0.45) and EM significantly reduced the MV duration (-2.01; -3.81 to -0.22). IMT+CPT and EM had the highest effectiveness in reducing the weaning duration and MV duration, respectively.

CONCLUSION

IMT or EM should be recommended for improving the weaning outcomes in mechanically ventilated patients. However, an interpretation with caution is required due to the heterogeneity.

Cambios fisiológicos relacionados con entrenamiento muscular respiratorio en pacientes con ventilación mecánica

Introducción. El entrenamiento muscular respiratorio es una técnica fisioterapéutica usada para incrementar la fuerza de la musculatura respiratoria, sin embargo pocos estudios han abordado los cambios fisiológicos relacionados con esta intervención en pacientes con ventilación mecánica.Objetivo. Determinar los cambios fisiológicos relacionados con el entrenamiento muscular respiratorio en pacientes con ventilación mecánica.Materiales y métodos. Se realizó un análisis de datos secundarios en el marco del estudio “Eficacia del entrenamiento muscular respiratorio en el destete de la ventilación mecánica en pacientes con ventilación mecánica por 48 horas o más: Un ensayo clínico controlado”. La población estuvo conformada por los 62 pacientes del grupo experimental del estudio principal, quienes recibieron entrenamiento muscular respiratorio. Los valores de frecuencia cardiaca, frecuencia respiratoria, presión arterial, saturación de oxígeno y volumen corriente fueron registrados. La diferencia entre el promedio de cada una de las variables fue analizada mediante la prueba de t pareada, mientras que para el análisis de los cambios fisiológicos entre sesiones de entrenamiento se empleó la prueba de Kruskal-Wallis.Resultados. Se observaron diferencias significativas entre las variables fisiológicas antes y después del entrenamiento muscular respiratorio (p<0.05), a excepción del volumen corriente y la presión arterial media (p>0.05). Por el contrario, no se observaron diferencias significativas en ninguna de las variables fisiológicas entre sesiones de entrenamiento (p>0.05)Conclusiones. El entrenamiento muscular respiratorio es una intervención terapéutica viable y tolerable en esta población.

Inspiratory Muscle Training to Enhance Weaning from Mechanical Ventilation

This report describes the use of specific inspiratory muscle training to enhance weaning from mechanical ventilation in a patient who had failed conventional weaning strategies. A 79-year-old man remained ventilator-dependent 17 days following laparotomy. A program of daily inspiratory muscle training was initiated. The mean training threshold increased progressively during the program and simultaneously the periods of unassisted breathing achieved gradually increased. By day 27, mechanical ventilation was no longer required. Inspiratory muscle training can be implemented effectively in the difficult to wean patient and should be considered for patients who have failed conventional weaning strategies.

Inspiratory Muscle Training in Patients with Prolonged Mechanical Ventilation: Narrative Review

Patients with impending respiratory failure often require mechanical ventilation to optimize gas exchange. Although this form of assisted ventilation is required for survival, its persistent use results in diaphragm weakness and muscle fiber atrophy. There is strong evidence that mechanical ventilation alters the structure and function of the diaphragm, resulting in prolonged dependence on assisted ventilation and long-term consequences such as a delayed functional recovery, reduced quality of life and increased risk of mortality. This review summarizes the mechanisms underlying diaphragm dysfunction due to prolonged mechanical ventilation, highlights the role of inspiratory muscle exercise as a strategy to counter diaphragm weakness, and identifies the parameters of an evidence-supported exercise prescription for difficult to wean patients.

Inspiratory muscle training for intensive care patients: A multidisciplinary practical guide for clinicians

OBJECTIVES

To describe a multidisciplinary approach to inspiratory muscle training (IMT) for patients in the intensive care unit (ICU).

BACKGROUND

Inspiratory muscle weakness is a known consequence of prolonged mechanical ventilation, and there is emerging evidence that specific IMT can ameliorate this weakness. However, IMT is not yet standard practice in many ICUs, possibly because of the wide variety of methods reported and a lack of published practical guidelines. While the optimal parameters for IMT are yet to be established, we share our detailed methodology which has been shown to be safe in selected ventilator-dependent patients and is the only approach which has been shown to increase quality of life in ICU patients.

METHODS

Patients who have experienced invasive mechanical ventilation for at least 7 days can commence IMT in either the ventilator-dependent phase or when weaned from mechanical ventilation. Intensity should be prescribed based on maximum inspiratory pressure, which is measurable through the tracheostomy or endotracheal tube via the ventilator or a respiratory pressure meter. Using a removable threshold device, we recommend high-intensity training (5 sets of 6 breaths at a minimum of 50% of maximum inspiratory pressure) performed once per day, supervised by the physiotherapist, with intensity increased daily such that patients can only just complete the 6th breath in each set.

RESULTS

Using this high-intensity approach, IMT is likely to improve not only inspiratory muscle strength but also quality of life in patients recently weaned from mechanical ventilation of 7 days' duration or longer. Effective IMT requires a multidisciplinary approach to maximise feasibility, with doctors, nurses, and therapists working closely to optimise conditions for successful IMT.

CONCLUSIONS

This multidisciplinary approach to implement IMT in ICU patients should assist clinicians in translating best-available evidence into practice, with the potential to enhance patient recovery.

An investigation into the use of ultrasound as a surrogate measure of diaphragm function

PURPOSE

Sonographic assessment of the diaphragm may be a surrogate for interpretation of diaphragm function in mechanically ventilated patients. This study aimed to determine the correlation between respiratory muscle function and diaphragm thickness in a healthy population.

METHODS

A descriptive study was conducted. Diaphragm thickness was determined by sonographic measurement. Respiratory muscle strength, fatigue and endurance was determined using a mouth pressure manometer.

RESULTS

55 subjects with a mean (SD) age 21.16 ± 1.55 years were studied. Diaphragm thickness was moderately correlated with strength (r = 0.52; r²=0.27; p < 0.001). Respiratory muscle fatigue was not correlated with thickness (r=-0.15; r²=0.02; p = 0.29) or strength (r=-0.19; r²=0.04; p = 0.16).

CONCLUSION

Diaphragm thickness was moderately correlated to strength but not to fatigue or endurance in healthy individuals. Sonography may be a surrogate measure of volitional respiratory muscle strength and requires confirmation in critically ill patients.

Short-Term Pulmonary Rehabilitation for a Female Patient with Chronic Scleroderma under a Single-Case Research Design

Although previously proposed that chronic scleroderma should be cared for clinically and early rehabilitation should be performed in hospital by a chest physical therapist, little evidence is currently available on its benefits. Therefore, this study demonstrated the benefits of short-term pulmonary rehabilitation during hospitalization in a female patient with chronic scleroderma. The aim of rehabilitation was to improve ventilation and gas exchange by using airway clearance, chest mobilization, and breathing-relearning techniques, including strengthening the respiratory system and the muscles of the limbs by using the BreathMax^® device and elastic bands. Gross motor function and activities of daily life were regained by balancing, sitting, and standing practices. Data on minimal chest expansion, high dyspnea, high respiratory rate, and low maximal inspiratory mouth pressure were recorded seven days before rehabilitation or at the baseline period. But there was a clinically significant improvement in dyspnea, chest expansion, maximal inspiratory mouth pressure, and respiratory rate, when compared to baseline data, which were recorded by a chest physical therapist during seven days of rehabilitation. Furthermore, physicians decided to stop using a mechanical ventilator, and improvement in functional capacity was noted. Therefore, in the case of chronic and stable scleroderma, short-term rehabilitation during hospitalization for chest physical therapy possibly shows clinical benefits by improving both pulmonary function and physical performance.

Leaky ryanodine receptors contribute to diaphragmatic weakness during mechanical ventilation

Ventilator-induced diaphragmatic dysfunction (VIDD) refers to the diaphragm muscle weakness that occurs following prolonged controlled mechanical ventilation (MV). The presence of VIDD impedes recovery from respiratory failure. However, the pathophysiological mechanisms accounting for VIDD are still not fully understood. Here, we show in human subjects and a mouse model of VIDD that MV is associated with rapid remodeling of the sarcoplasmic reticulum (SR) Ca(2+) release channel/ryanodine receptor (RyR1) in the diaphragm. The RyR1 macromolecular complex was oxidized, S-nitrosylated, Ser-2844 phosphorylated, and depleted of the stabilizing subunit calstabin1, following MV. These posttranslational modifications of RyR1 were mediated by both oxidative stress mediated by MV and stimulation of adrenergic signaling resulting from the anesthesia. We demonstrate in the murine model that such abnormal resting SR Ca(2+) leak resulted in reduced contractile function and muscle fiber atrophy for longer duration of MV. Treatment with β-adrenergic antagonists or with S107, a small molecule drug that stabilizes the RyR1-calstabin1 interaction, prevented VIDD. Diaphragmatic dysfunction is common in MV patients and is a major cause of failure to wean patients from ventilator support. This study provides the first evidence to our knowledge of RyR1 alterations as a proximal mechanism underlying VIDD (i.e., loss of function, muscle atrophy) and identifies RyR1 as a potential target for therapeutic intervention.

Inspiratory muscle training to enhance recovery from mechanical ventilation: a randomised trial

Background

In patients who have been mechanically ventilated, inspiratory muscles remain weak and fatigable following ventilatory weaning, which may contribute to dyspnoea and limited functional recovery. Inspiratory muscle training may improve inspiratory muscle strength and endurance following weaning, potentially improving dyspnoea and quality of life in this patient group.

Methods

We conducted a randomised trial with assessor-blinding and intention-to-treat analysis. Following 48 hours of successful weaning, 70 participants (mechanically ventilated ≥7 days) were randomised to receive inspiratory muscle training once daily 5 days/week for 2 weeks in addition to usual care, or usual care (control). Primary endpoints were inspiratory muscle strength and fatigue resistance index (FRI) 2 weeks following enrolment. Secondary endpoints included dyspnoea, physical function and quality of life, post-intensive care length of stay and in-hospital mortality.

Results

34 participants were randomly allocated to the training group and 36 to control. The training group demonstrated greater improvements in inspiratory strength (training: 17%, control: 6%, mean difference: 11%, p=0.02). There were no statistically significant differences in FRI (0.03 vs 0.02, p=0.81), physical function (0.25 vs 0.25, p=0.97) or dyspnoea (−0.5 vs 0.2, p=0.22). Improvement in quality of life was greater in the training group (14% vs 2%, mean difference 12%, p=0.03). In-hospital mortality was higher in the training group (4 vs 0, 12% vs 0%, p=0.051).

Conclusions

Inspiratory muscle training following successful weaning increases inspiratory muscle strength and quality of life, but we cannot confidently rule out an associated increased risk of in-hospital mortality.

Trial registration number

ACTRN12610001089022, results.

Influence of inspiratory muscle training on weaning patients from mechanical ventilation: a systematic review

Abstract Introduction: The inability of respiratory muscles to generate force and endurance is recognized as an important cause of failure in weaning patients from invasive mechanical ventilation (IMV). Thus, inspiratory muscle training (IMT) might be an interesting treatment option for patients with prolonged IMV weaning. Objective: The aim of this systematic literature review was to evaluate the effectiveness of inspiratory muscle training in weaning patients from mechanical ventilation and to identify the most effective type of training for this particular purpose. Methods: We searched PubMed, LILACS, PEDro and Web of Science for randomized clinical trials published in English or Portuguese from January 1990 until March 2015. Results: Eighty-nine studies were identified of which five were selected. A total of 267 patients participated in the five randomized clinical trials analyzed here. IMV duration before onset of training varied greatly among subjects. Three studies performed IMT using a threshold device and two studies used adjustments of ventilator pressure sensitivity. Four studies have shown that IMT resulted in a significant increase in inspiratory maximal pressure. Only two studies, however, have reported that IMT resulted in higher success rates in weaning patients from IMV. One study has found that patients showed a shorter ventilator weaning duration after IMT. Conclusion: IMT using pressure threshold devices results in increased inspiratory muscle strength and can therefore be considered a more effective treatment option and with the potential to optimize ventilator weaning success in patients at risk of prolonged IMV.

Computed tomography confirms a reduction in diaphragm thickness in mechanically ventilated patients

PURPOSE

Patients who require mechanical ventilation (MV) may experience diaphragm atrophy, which may delay the discontinuation of MV. Here, we used computed tomographic (CT) scans to confirm this phenomenon.

METHOD AND MATERIALS

Patients who underwent two chest CT scans while on MV were retrospectively evaluated. Diaphragm thickness was measured using a three-dimensional CT image processing program.

RESULTS

Thirteen patients, including 8 men, who underwent 26 CT scans were assessed. The mean age was 67.8 ± 7.5 years. The interval between CT scans was 18.4 ± 14.9 days. The first CT scans revealed that the mean thicknesses of the left and right sides of the diaphragm were 3.8 ± 0.6 and 3.9 ± 0.8 mm, respectively (total: 7.7 ± 1.4 mm). These values were significantly reduced to 3.4 ± 0.6 and 3.5 ± 0.9 mm, respectively, (total: 6.9 ± 1.5 mm) after the second scan (P < .01). No significant change in body weight (57.3 ± 12.6 vs. 56.7 ± 11.6 kg) or body mass index (21.8 ± 5.1 vs. 21.6 ± 4.8 kg/m(2)) was observed.

CONCLUSION

Computed tomography confirmed that diaphragm thickness was reduced in critically ill patients who underwent MV.

Inspiratory muscle training facilitates weaning from mechanical ventilation among patients in the intensive care unit: a systematic review

QUESTION

Does inspiratory muscle training improve inspiratory muscle strength in adults receiving mechanical ventilation? Does it improve the duration or success of weaning? Does it affect length of stay, reintubation, tracheostomy, survival, or the need for post-extubation non-invasive ventilation? Is it tolerable and does it cause adverse events?

DESIGN

Systematic review of randomised trials.

PARTICIPANTS

Adults receiving mechanical ventilation.

INTERVENTION

Inspiratory muscle training versus sham or no inspiratory muscle training.

OUTCOME MEASURES

Data were extracted regarding: inspiratory muscle strength and endurance; the rapid shallow breathing index; weaning success and duration; duration of mechanical ventilation; reintubation; tracheostomy; length of stay; use of non-invasive ventilation after extubation; survival; readmission; tolerability and adverse events.

RESULTS

Ten studies involving 394 participants were included. Heterogeneity within some meta-analyses was high. Random-effects meta-analyses showed that the training significantly improved maximal inspiratory pressure (MD 7 cmH2O, 95% CI 5 to 9), the rapid shallow breathing index (MD 15 breaths/min/l, 95% CI 8 to 23) and weaning success (RR 1.34, 95% CI 1.02 to 1.76). Although only assessed in individual studies, significant benefits were also reported for the time spent on non-invasive ventilation after weaning (MD 16 hours, 95% CI 13 to 18), length of stay in the intensive care unit (MD 4.5 days, 95% CI 3.6 to 5.4) and length of stay in hospital (MD 4.4 days, 95% CI 3.4 to 5.5). Weaning duration decreased in the subgroup of patients with known weaning difficulty. The other outcomes weren't significantly affected or weren't measured.

CONCLUSION

Inspiratory muscle training for selected patients in the intensive care unit facilitates weaning, with potential reductions in length of stay and the duration of non-invasive ventilatory support after extubation. The heterogeneity among the results suggests that the effects of inspiratory muscle training may vary; this perhaps depends on factors such as the components of usual care or the patient's characteristics.

Ventilator-induced diaphragm dysfunction: cause and effect

Mechanical ventilation (MV) is used clinically to maintain gas exchange in patients that require assistance in maintaining adequate alveolar ventilation. Common indications for MV include respiratory failure, heart failure, drug overdose, and surgery. Although MV can be a life-saving intervention for patients suffering from respiratory failure, prolonged MV can promote diaphragmatic atrophy and contractile dysfunction, which is referred to as ventilator-induced diaphragm dysfunction (VIDD). This is significant because VIDD is thought to contribute to problems in weaning patients from the ventilator. Extended time on the ventilator increases health care costs and greatly increases patient morbidity and mortality. Research reveals that only 18–24 h of MV is sufficient to develop VIDD in both laboratory animals and humans. Studies using animal models reveal that MV-induced diaphragmatic atrophy occurs due to increased diaphragmatic protein breakdown and decreased protein synthesis. Recent investigations have identified calpain, caspase-3, autophagy, and the ubiquitin-proteasome system as key proteases that participate in MV-induced diaphragmatic proteolysis. The challenge for the future is to define the MV-induced signaling pathways that promote the loss of diaphragm protein and depress diaphragm contractility. Indeed, forthcoming studies that delineate the signaling mechanisms responsible for VIDD will provide the knowledge necessary for the development of a pharmacological approach that can prevent VIDD and reduce the incidence of weaning problems.

Respiratory Dysfunction in Ventilated Patients: Can Inspiratory Muscle Training Help?

Respiratory muscle dysfunction is associated with prolonged and difficult weaning from mechanical ventilation. This dysfunction in ventilator-dependent patients is multifactorial: there is evidence that inspiratory muscle weakness is partially explained by disuse atrophy secondary to ventilation, and positive end-expiratory pressure can further reduce muscle strength by negatively shifting the length-tension curve of the diaphragm. Polyneuropathy is also likely to contribute to apparent muscle weakness in critically ill patients, and nutritional and pharmaceutical effects may further compound muscle weakness. Moreover, psychological influences, including anxiety, may contribute to difficulty in weaning. There is recent evidence that inspiratory muscle training is safe and feasible in selected ventilator-dependent patients, and that this training can reduce the weaning period and improve overall weaning success rates. Extrapolating from evidence in sports medicine, as well as the known effects of inspiratory muscle training in chronic lung disease, a theoretical model is proposed to describe how inspiratory muscle training enhances weaning and recovery from mechanical ventilation. Possible mechanisms include increased protein synthesis (both Type 1 and Type 2 muscle fibres), enhanced limb perfusion via dampening of a sympathetically-mediated metaboreflex, reduced lactate levels and modulation of the perception of exertion, resulting in less dyspnoea and enhanced exercise capacity.

Inspiratory muscle training increases inspiratory muscle strength in patients weaning from mechanical ventilation: a systematic review

QUESTION

Does inspiratory muscle training improve inspiratory muscle strength and endurance, facilitate weaning, improve survival, and reduce the rate of reintubation and tracheostomy in adults receiving mechanical ventilation?

DESIGN

Systematic review of randomised or quasi-randomised controlled trials.

PARTICIPANTS

Adults over 16 years of age receiving mechanical ventilation.

INTERVENTION

Inspiratory muscle training versus sham or no inspiratory muscle training.

OUTCOME MEASURES

Data were extracted regarding inspiratory muscle strength and endurance, the duration of unassisted breathing periods, weaning success and duration, reintubation and tracheostomy, survival, adverse effects, and length of stay.

RESULTS

Three studies involving 150 participants were included in the review. The studies varied in time to commencement of the training, the device used, the training protocol, and the outcomes measured. Inspiratory muscle training significantly increased inspiratory muscle strength over sham or no training (weighted mean difference 8 cmH(2)O, 95% CI 6 to 9). There were no statistically significant differences between the groups in weaning success or duration, survival, reintubation, or tracheostomy.

CONCLUSION

Inspiratory muscle training was found to significantly increase inspiratory muscle strength in adults undergoing mechanical ventilation. Despite data from a substantial pooled cohort, it is not yet clear whether the increase in inspiratory muscle strength leads to a shorter duration of mechanical ventilation, improved weaning success, or improved survival. Further large randomised studies are required to clarify the impact of inspiratory muscle training on patients receiving mechanical ventilation.

REVIEW REGISTRATION

PROSPERO CRD42011001132.

Inspiratory muscle training to facilitate weaning from mechanical ventilation: protocol for a systematic review

Background

In intensive care, weaning is the term used for the process of withdrawal of mechanical ventilation to enable spontaneous breathing to be re-established. Inspiratory muscle weakness and deconditioning are common in patients receiving mechanical ventilation, especially that of prolonged duration. Inspiratory muscle training could limit or reverse these unhelpful sequelae and facilitate more rapid and successful weaning.

Methods

This review will involve systematic searching of five electronic databases to allow the identification of randomised trials of inspiratory muscle training in intubated and ventilated patients. From these trials, we will extract available data for a list of pre-defined outcomes, including maximal inspiratory pressure, the duration of the weaning period, and hospital length of stay. We will also meta-analyse comparable results where possible, and report a summary of the available pool of evidence.

Discussion

The data generated by this review will be the most comprehensive answer available to the question of whether inspiratory muscle training is clinically useful in intensive care. As well as informing clinicians in the intensive care setting, it will also inform healthcare managers deciding whether health professionals with skills in respiratory therapy should be made available to provide this sort of intervention. Through the publication of this protocol, readers will ultimately be able to assess whether the review was conducted according to a pre-defined plan. Researchers will be aware that the review is underway, thereby avoid duplication, and be able to use it as a basis for planning similar reviews.

Efeitos da posição sentada na força de músculos respiratórios durante o desmame de pacientes sob ventilação mecânica prolongada no pós-operatório de cirurgia cardiovascular

O objetivo do estudo foi investigar os efeitos da posição sentada, nos parâmetros ventilatórios e hemodinâmicos, em pacientes com suporte ventilatório mecânico prolongado, estáveis hemodinamicamente. Participaram do estudo 40 pacientes que foram randomizados em grupo controle (n=17) e grupo intervenção (n=23). Foram mensurados parâmetros hemodinâmicos, gasometria arterial, força muscular respiratória e ventilometria, realizados em dois momentos: primeira e segunda avaliação, com intervalo de 30 minutos entre as medidas. No grupo controle, as duas avaliações foram realizadas no leito, com a cabeceira elevada a 30°. No grupo intervenção, a primeira avaliação foi realizada no leito (30°) e a segunda, 30 minutos após transferência para a poltrona, na posição sentada (90°). A idade média da amostra foi de 64,7±11,2 anos. O resultado do estudo demonstrou que não houve diferenças em relação às variáveis, hemodinâmicas, gasométricas, capacidade vital forçada, volume minuto e volume de ar corrente. Entretanto, ocorreu aumento significativo da pressão inspiratória máxima (PImáx) no grupo intervenção (p<0.01). Concluímos que pacientes em pós-operatório de cirurgia cardiovascular em ventilação mecânica podem se beneficiar da posição sentada durante o desmame do suporte ventilatório, observado pela melhora da força muscular inspiratória (PImáx). Além disso, não foram observadas alterações hemodinâmicas com a troca de postura, sendo considerado um procedimento seguro.

Inspiratory muscle training improves maximal inspiratory pressure and may assist weaning in older intubated patients: a randomised trial

QUESTIONS

Does inspiratory muscle training improve maximal inspiratory pressure in intubated older people? Does it improve breathing pattern and time to wean from mechanical ventilation?

DESIGN

Randomised trial with concealed allocation and intention-to-treat analysis.

PARTICIPANTS

41 elderly, intubated adults who had been mechanically ventilated for at least 48 hr in an intensive care unit.

INTERVENTION

The experimental group received usual care plus inspiratory muscle training using a threshold device, with an initial load of 30% of their maximal inspiratory pressure, increased by 10% (absolute) daily. Training was administered for 5 min, twice a day, 7 days a week from the commencement of weaning until extubation. The control group received usual care only.

OUTCOME MEASURES

The primary outcome was the change in maximal inspiratory pressure during the weaning period. Secondary outcomes were the weaning time (ie, from commencement of pressure support ventilation to successful extubation), and the index of Tobin (ie, respiratory rate divided by tidal volume during a 1-min spontaneous breathing trial).

RESULTS

Maximal inspiratory pressure increased significantly more in the experimental group than in the control group (MD 7.6 cmH(2)0, 95% CI 5.8 to 9.4). The index of Tobin decreased significantly more in the experimental group than in the control group (MD 8.3 br/min/L, 95% CI 2.9 to 13.7). In those who did not die or receive a tracheostomy, time to weaning was significantly shorter in the experimental group than in the control group (MD 1.7 days, 95% CI 0.4 to 3.0).

CONCLUSIONS

In intubated older people, inspiratory muscle training improves maximal inspiratory pressure and the index of Tobin, with a reduced weaning time in some patients.

TRIAL REGISTRATION

NCT00922493.

Case report: inspiratory muscle training in chronic critically ill patients--a report of two cases

BACKGROUND AND PURPOSE

Inspiratory muscle weakness and fatigue has been documented following prolonged mechanical ventilation despite successful weaning from mechanical ventilation. This report describes the application of inspiratory muscle training in two patients following successful discharge from an intensive care unit (ICU) after prolonged mechanical ventilation.

METHODS

Both patients undertook inspiratory muscle training in conjunction with standard physiotherapy rehabilitation.

RESULTS

Improvements in inspiratory muscle strength and endurance, exercise tolerance and functional performance following twice-daily inspiratory muscle training were recorded. In both cases, an improvement in maximal inspiratory pressure (MIP) and maximal tolerated inspiratory load (MIP(load)) was found following training.

CONCLUSION

These positive results indicate further research is needed to investigate the effect of inspiratory muscle training on respiratory function, exercise tolerance and functional performance, for the possible inclusion of inspiratory muscle training into the physiotherapy management of patients following prolonged mechanical ventilation.