Weaned but weary: One third of adult intensive care patients mechanically ventilated for 7 days or more have impaired inspiratory muscle endurance after successful weaning

Feasibility, safety, and patient acceptability of electronic inspiratory muscle training in patients who require prolonged mechanical ventilation in the intensive care unit: A dual-centre observational study

BACKGROUND

Inspiratory muscle training (IMT) is an intervention that can be used to rehabilitate the respiratory muscle deconditioning experienced by patients with critical illness, requiring prolonged mechanical ventilation. Clinicians are currently using mechanical threshold IMT devices that have limited resistance ranges.

OBJECTIVES

The objective of this study was to evaluate the safety, feasibility, and acceptability of using an electronic device to facilitate IMT with participants requiring prolonged mechanical ventilation.

METHOD

A dual-centre observational cohort study, with convenience sampling, was conducted at two tertiary intensive care units. Daily training supervised by intensive care unit physiotherapists was completed with the electronic IMT device. A priori definitions for feasibility, safety, and acceptability were determined. Feasibility was defined as more than 80% of planned sessions completed. Safety was defined as no major adverse events and less than 3% minor adverse event rate, and acceptability was evaluated following the acceptability of intervention framework principles.

RESULTS

Forty participants completed 197 electronic IMT treatment sessions. Electronic IMT was feasible, with 81% of planned sessions completed. There were 10% minor adverse events and no major adverse events. All the minor adverse events were transient without clinical consequences. All the participants who recalled completing electronic IMT sessions reported that the training was acceptable. Acceptability was demonstrated; over 85% of participants reported that electronic IMT was either helpful or beneficial and that electronic IMT assisted their recovery.

CONCLUSION

Electronic IMT is feasible and acceptable to complete with critically ill participants who require prolonged mechanical ventilation. As all minor adverse events were transient without clinical consequences, electronic IMT can be considered a relatively safe intervention with patients who require prolonged mechanical ventilation.

Research progress on the pathogenesis and treatment of ventilator-induced diaphragm dysfunction

Prolonged controlled mechanical ventilation (CMV) can cause diaphragm fiber atrophy and inspiratory muscle weakness, resulting in diaphragmatic contractile dysfunction, called ventilator-induced diaphragm dysfunction (VIDD). VIDD is associated with higher rates of in-hospital deaths, nosocomial pneumonia, difficulty weaning from ventilators, and increased costs. Currently, appropriate clinical strategies to prevent and treat VIDD are unavailable, necessitating the importance of exploring the mechanisms of VIDD and suitable treatment options to reduce the healthcare burden. Numerous animal studies have demonstrated that ventilator-induced diaphragm dysfunction is associated with oxidative stress, increased protein hydrolysis, disuse atrophy, and calcium ion disorders. Therefore, this article summarizes the molecular pathogenesis and treatment of ventilator-induced diaphragm dysfunction in recent years so that it can be better served clinically and is essential to reduce the duration of mechanical ventilation use, intensive care unit (ICU) length of stay, and the medical burden.

The metabolic cost of inspiratory muscle training in mechanically ventilated patients in critical care

BACKGROUND

Diaphragmatic dysfunction is well documented in patients receiving mechanical ventilation. Inspiratory muscle training (IMT) has been used to facilitate weaning by strengthening the inspiratory muscles, yet the optimal approach remains uncertain. Whilst some data on the metabolic response to whole body exercise in critical care exist, the metabolic response to IMT in critical care is yet to be investigated. This study aimed to quantify the metabolic response to IMT in critical care and its relationship to physiological variables.

METHODS

We conducted a prospective observational study on mechanically ventilated patients ventilated for ≥ 72 h and able to participate in IMT in a medical, surgical, and cardiothoracic intensive care unit. 76 measurements were taken on 26 patients performing IMT using an inspiratory threshold loading device at 4 cmH₂O, and at 30, 50 and 80% of their negative inspiratory force (NIF). Oxygen consumption (VO₂) was measured continuously using indirect calorimetry.

RESULTS

First session mean (SD) VO₂ was 276 (86) ml/min at baseline, significantly increasing to 321 (93) ml/min, 333 (92) ml/min, 351(101) ml/min and 388 (98) ml/min after IMT at 4 cmH₂O and 30, 50 and 80% NIF, respectively (p = 0.003). Post hoc comparisons revealed significant differences in VO₂ between baseline and 50% NIF and baseline and 80% NIF (p = 0.048 and p = 0.001, respectively). VO₂ increased by 9.3 ml/min for every 1 cmH₂O increase in inspiratory load from IMT. Every increase in P/F ratio of 1 decreased the intercept VO₂ by 0.41 ml/min (CI - 0.58 to - 0.24 p < 0.001). NIF had a significant effect on the intercept and slope, with every 1 cmH₂O increase in NIF increasing intercept VO₂ by 3.28 ml/min (CI 1.98-4.59 p < 0.001) and decreasing the dose-response slope by 0.15 ml/min/cmH₂O (CI - 0.24 to - 0.05 p = 0.002).

CONCLUSIONS

IMT causes a significant load-dependent increase in VO₂. P/F ratio and NIF impact baseline VO₂. The dose-response relationship of the applied respiratory load during IMT is modulated by respiratory strength. These data may offer a novel approach to prescription of IMT.

TAKE HOME MESSAGE

The optimal approach to IMT in ICU is uncertain; we measured VO₂ at different applied respiratory loads to assess whether VO₂ increased proportionally with load and found VO₂ increased by 9.3 ml/min for every 1 cmH₂O increase in inspiratory load from IMT. Baseline NIF has a significant effect on the intercept and slope, participants with a higher baseline NIF have a higher resting VO₂ but a less pronounced increase in VO₂ as the inspiratory load increases; this may offer a novel approach to IMT prescription. Trial registration ClinicalTrials.gov, registration number: NCT05101850. Registered on 28 September 2021, https://clinicaltrials.gov/ct2/show/NCT05101850.

Dyspnoea in COVID-19 recovery beyond the intensive care unit: the potential impact of inspiratory muscle weakness

Emerging evidence confirms that dyspnoea and inspiratory muscle weakness persist for up to 6 months following mechanical ventilation with #COVID19 pneumonia. Screening for inspiratory muscle weakness should be prioritised, as it may be treatable. https://bit.ly/3CBQXO2.

Pulmonary function test and computed tomography features during follow-up after SARS, MERS and COVID-19: a systematic review and meta-analysis

Background

The COVID-19 pandemic follows severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronavirus epidemics. Some survivors of COVID-19 infection experience persistent respiratory symptoms, yet their cause and natural history remain unclear. Follow-up after SARS and MERS may provide a model for predicting the long-term pulmonary consequences of COVID-19.

Methods

This systematic review and meta-analysis aims to describe and compare the longitudinal pulmonary function test (PFT) and computed tomography (CT) features of patients recovering from SARS, MERS and COVID-19. Meta-analysis of PFT parameters (DerSimonian and Laird random-effects model) and proportion of CT features (Freeman-Tukey transformation random-effects model) were performed.

Findings

Persistent reduction in the diffusing capacity for carbon monoxide following SARS and COVID-19 infection is seen at 6 months follow-up, and 12 months after MERS. Other PFT parameters recover in this time. 6 months after SARS and COVID-19, ground-glass opacity, linear opacities and reticulation persist in over 30% of patients; honeycombing and traction dilatation are reported less often. Severe/critical COVID-19 infection leads to greater CT and PFT abnormality compared to mild/moderate infection.

Interpretation

Persistent diffusion defects suggestive of parenchymal lung injury occur after SARS, MERS and COVID-19 infection, but improve over time. After COVID-19 infection, CT features are suggestive of persistent parenchymal lung injury, in keeping with a post-COVID-19 interstitial lung syndrome. It is yet to be determined if this is a regressive or progressive disease.

Prolonged Mechanical Ventilation: Outcomes and Management

The number of patients requiring prolonged mechanical ventilation (PMV) is increasing worldwide, placing a burden on healthcare systems. Therefore, investigating the pathophysiology, risk factors, and treatment for PMV is crucial. Various underlying comorbidities have been associated with PMV. The pathophysiology of PMV includes the presence of an abnormal respiratory drive or ventilator-induced diaphragm dysfunction. Numerous studies have demonstrated that ventilator-induced diaphragm dysfunction is related to increases in in-hospital deaths, nosocomial pneumonia, oxidative stress, lung tissue hypoxia, ventilator dependence, and costs. Thus far, the pathophysiologic evidence for PMV has been derived from clinical human studies and experimental studies in animals. Moreover, recent studies have demonstrated the outcome benefits of pharmacological agents and rehabilitative programs for patients requiring PMV. However, methodological limitations affected these studies. Controlled prospective studies with an adequate number of participants are necessary to provide evidence of the mechanism, prognosis, and treatment of PMV. The great epidemiologic impact of PMV and the potential development of treatment make this a key research field.

Physical outcomes of patients infected with HIV requiring intensive care unit admission for mechanical ventilation at one South African hospital: a pilot study

Patients with life-threatening illnesses in intensive care receive management that improves their chances for survival. The physical outcomes of individuals infected with HIV who survive an intensive care unit (ICU) stay are not well known. The purpose was to describe the physical outcomes of ICU survivors in a high HIV prevalent area and highlight challenges as it relates to study feasibility. A pilot study at a tertiary-care university-affiliated hospital was done. Participants were assessed at ICU and ward admission, hospital discharge, three and six months following discharge. The profile and physical function, assessed with the ICU Mobility Scale, Karnofsky Performance Status Scale and six-minute walk test, of participants was determined. The EQ-5D-3 L provides information on participants' health-related quality of life (HRQOL). The pilot study consists of five patients (n = 173 screened). All were independently mobile and on antiretroviral therapy prior to hospital admission. Respiratory and peripheral muscle weakness were present with variable performance in physical function across participants. Improvement in function occurred over time but participants still had physical dysfunction at six months. Pain/physical discomfort and anxiety/depression were common complaints influencing HRQOL. ICU survivors, who are HIV-positive, present with significant physical dysfunction who require rehabilitation to reduce disability.

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.

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.

Respiratory Muscle Rehabilitation in Patients with Prolonged Mechanical Ventilation: A Targeted Approach

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Which ICU patients benefit most from inspiratory muscle training? Retrospective analysis of a randomized trial

Background: Inspiratory muscle training (IMT) increases inspiratory muscle strength and improves quality of life in intensive care unit (ICU) patients who have been invasively mechanically ventilated for ≥7 days. The purpose of this study was to identify which patients benefit most from IMT following weaning from mechanical ventilation. Methods: Secondary analysis of a randomized trial of supervised daily IMT in 70 patients (mean age 59 years) in a 31-bed ICU was carried out. Changes in inspiratory muscle strength (maximum inspiratory pressure, MIP) between enrolment and 2 weeks (ΔMIP) were analyzed to compare the IMT group (71% male) and the control group (58% male). Linear regression models explored which factors at baseline were associated with ΔMIP. Results: Thirty-four participants were allocated to the IMT group where baseline MIP was associated with an increase in ΔMIP, significantly different from the control group (p = 0.025). The highest ΔMIP was associated with baseline MIP ≥ 28 cmH₂O. In the IMT group, higher baseline quality of life (EQ5D) scores were associated with positive ΔMIP, significantly different from the control group (p = 0.029), with largest ΔMIP for those with EQ5D ≥ 40. Conclusions: Physiotherapists should target ICU patients with moderate inspiratory muscle weakness (MIP ≥28 cmH₂O) and moderate to high quality of life (EQ5D>40) within 48 h of ventilatory weaning as ideal candidates for IMT following prolonged mechanical ventilation.

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.

Self-reported fatigue following intensive care of chronically critically ill patients: a prospective cohort study

Background

Protracted treatment on intensive care unit (ICU) sets the patients at increased risk for the development of chronic critical illness (CCI). Muscular and cardio-respiratory deconditioning are common long-term sequelae, going along with a state of chronic fatigue. At present, findings regarding the frequency, long-term course, and associated factors of self-reported fatigue following ICU treatment of CCI patients are lacking.

Methods

CCI patients with the diagnosis of critical illness polyneuropathy/myopathy (CIP/CIM) were assessed at three time points. Four weeks following the discharge from ICU at acute care hospital (t1), eligibility for study participation was asserted. Self-reported fatigue was measured using the Multidimensional Fatigue Inventory (MFI-20) via telephone contact at 3 (t2, n = 113) and 6 months (t3, n = 91) following discharge from ICU at acute care hospital.

Results

At both 3 and 6 months, nearly every second CCI patient showed clinically relevant fatigue symptoms (t2/t3: n = 53/n = 51, point prevalence rates: 46.9%/45.1%). While total fatigue scores remained stable in the whole sample, female patients showed a decrease from 3 to 6 months. The presence of a coronary heart disease, the perceived fear of dying at acute care ICU, a diagnosis of major depression, and the perceived social support were confirmed as significant correlates of fatigue at 3 months. At 6 months, male gender, the number of medical comorbidities, a diagnosis of major depression, and a prior history of anxiety disorder could be identified. A negative impact of fatigue on the perceived health-related quality of life could be ascertained.

Conclusions

Nearly every second CCI patient showed fatigue symptoms up to 6 months post-ICU. Patients at risk should be informed about fatigue, and appropriate treatment options should be offered to them.

Trial registration

The present study was registered retrospectively at the German Clinical Trials Register (date of registration: 13th of December 2011; registration number: DRKS00003386). Date of enrolment of the first participant to the present trial: 09th of November 2011.

Inspiratory Muscle Training in the Intensive Care Unit: A New Perspective

Background

Prolonged use of mechanical ventilation (MV) leads to weakening of the respiratory muscles, especially in patients subjected to sedation, but this effect seems to be preventable or more quickly reversible using respiratory muscle training. The aims of the study were to assess variations in respiratory and hemodinamic parameters with electronic inspiratory muscle training (EIMT) in tracheostomized patients requiring MV and to compare these variations with those in a group of patients subjected to an intermittent nebulization program (INP).

Methods

This was a pilot, prospective, randomized study of tracheostomized patients requiring MV in one intensive care unit (ICU). Twenty-one patients were randomized: 11 into the INP group and 10 into the EIMT group. Two patients were excluded in experimental group because of hemodynamic instability.

Results

In the EIMT group, maximal inspiratory pressure (MIP) after training was significantly higher than that before (P = 0.017), there were no hemodynamic changes, and the total weaning time was shorter than in the INP group (P = 0.0192).

Conclusion

The EIMT device is safe, promotes an increase in MIP, and leads to a shorter ventilator weaning time than that seen in patients treated using INP.

Mitigation of Ventilator-induced Diaphragm Atrophy by Transvenous Phrenic Nerve Stimulation

RATIONALE

Ventilator-induced diaphragm dysfunction is a significant contributor to weaning difficulty in ventilated critically ill patients. It has been hypothesized that electrically pacing the diaphragm during mechanical ventilation could reduce diaphragm dysfunction.

OBJECTIVES

We tested a novel, central line catheter-based, transvenous phrenic nerve pacing therapy for protecting the diaphragm in sedated and ventilated pigs.

METHODS

Eighteen Yorkshire pigs were studied. Six pigs were sedated and mechanically ventilated for 2.5 days with pacing on alternate breaths at intensities that reduced the ventilator pressure-time product by 20-30%. Six matched subjects were similarly sedated and ventilated but were not paced. Six pigs served as never-ventilated, never-paced control animals.

MEASUREMENTS AND MAIN RESULTS

Cumulative duration of pacing therapy ranged from 19.7 to 35.7 hours. Diaphragm thickness assessed by ultrasound and normalized to initial value showed a significant decline in ventilated-not paced but not in ventilated-paced subjects (0.84 [interquartile range (IQR), 0.78-0.89] vs. 1.10 [IQR, 1.02-1.24]; P = 0.001). Compared with control animals (24.6 μm²/kg; IQR, 21.6-26.0), median myofiber cross-sectional areas normalized to weight and sarcomere length were significantly smaller in the ventilated-not paced (17.9 μm²/kg; IQR, 15.3-23.7; P = 0.005) but not in the ventilated-paced group (24.9 μm²/kg; IQR, 16.6-27.3; P = 0.351). After 60 hours of mechanical ventilation all six ventilated-paced subjects tolerated 8 minutes of intense phrenic stimulation, whereas three of six ventilated-not paced subjects did not (P = 0.055). There was a nonsignificant decrease in diaphragm tetanic force production over the experiment in the ventilated-paced and ventilated-not paced groups.

CONCLUSIONS

These results suggest that early transvenous phrenic nerve pacing may mitigate ventilator-induced diaphragm dysfunction.

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.

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.