PURPOSE: One of the most important consequences of smoking is the development of cardiovascular diseases. However, little is known about the early consequences of smoking and the acute effects of a single inspiratory muscle exercise session (IME). We evaluated the acute effects of an IME on cardiac parameters of young smokers.
METHODS: Twelve nonsmokers (C) and fifteen smokers [S; 2.08 (1.0-3.2) pack-years] underwent an acute IME. We evaluated blood pressure (BP) and lactate, and we recorded RR interval for posterior analysis of heart rate variability (HRV), before and after IME.
RESULTS: At baseline, systolic BP and HRV parameters in time and frequency domains were changed in S group in comparison with the C. Following IME, S group reduced systolic BP (-8 %), low frequency band (LF) (-21.4 %), LF/high frequency (HF) (-57 %), as well as increased RR variance (+105 %) and HF band.
CONCLUSIONS: Our findings indicate that a single session of inspiratory muscle exercise was able to both reduce systolic BP and improve parasympathetic and sympathetic modulations in young smokers. The results of the current study highlight the importance of furthering research on this area to better elucidate the acute and chronic effects of inspiratory muscle training on early cardiovascular and pulmonary changes of cigarette smoking.
PMID: 23812534 DOI: 10.1007/s10286-013-0202-1

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.
KEYWORDS: Exercise; Respiratory Measurement; Respiratory Muscles
PMID: 27257003 PMCID: PMC5013088 DOI: 10.1136/thoraxjnl-2016-208279

Definitely, mechanical ventilation (MV) is a life-saving treatment in the intensive care unit (ICU), but it is also a double-edged sword. Forty percent of the overall time spent in the ICU was reported to be devoted to weaning of MV. The major cause of weaning failure is the imbalance between the imposed load on the respiratory system and its capacity to overcome that. Thus, since the 1980’s numerous studies with inspiratory muscle training (IMT) have been conducted in an attempt to reduce weaning and MV time in prolonged mechanically ventilated patients. Despite dozens of published research, only 5 randomized controlled trials (RCT) were conducted until this date. Nevertheless, it was not yet clear whether IMT led to a shorter duration of mechanical ventilation, improved weaning success, or improved survival. These RCT show considerable heterogeneity among them and possible bias that could have impaired their results. Thus, some questions may be made to highlight main points: What is the ideal prescription of IMT for patients on MV? What is the best time to measure treatment effect? Which kind of device should be used to IMT? What are the best endpoints to evaluate the effects of IMT on the process of discontinuing from MV? IMT on mechanically ventilated patients seems to be a promissory treatment despite controversial results. Therefore, RCTs should be carried out to verify the efficacy of new protocols in different approaches.
Keywords: Breathing exercises; Extubation; Inspiratory muscle training; Physiotherapy; Ventilator dependence; Ventilator weaning.

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.
KEYWORDS: Intensive care; Mechanical ventilators; Physiotherapy; Respiratory muscle training; Systematic review; Weaning
PMID: 26092389 DOI: 10.1016/j.jphys.2015.05.016

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. PMID: 22417017 DOI: 10.1177/0310057X1204000205