Learned activation of thoracic inspiratory muscles in tetraplegics

Respiratory muscle training for cervical spinal cord injury

BACKGROUND

Cervical spinal cord injury (SCI) severely comprises respiratory function due to paralysis and impairment of the respiratory muscles. Various types of respiratory muscle training (RMT) to improve respiratory function for people with cervical SCI have been described in the literature. A systematic review of this literature is needed to determine the effectiveness of RMT (either inspiratory or expiratory muscle training) on pulmonary function, dyspnoea, respiratory complications, respiratory muscle strength, and quality of life for people with cervical SCI.

OBJECTIVES

To evaluate the efficacy of RMT versus standard care or sham treatments in people with cervical SCI.

SEARCH METHODS

We searched the Cochrane Injuries and Cochrane Neuromuscular Disease Groups' Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 1), MEDLINE, EMBASE, CINAHL, ISI Web of Science, PubMed, and clinical trials registries (Australian New Zealand Clinical Trials Registry, ClinicalTrials, Controlled Trials metaRegister) on 5 to 8 March 2013. We handsearched reference lists of relevant papers and literature reviews. We applied no date, language, or publication restrictions.

SELECTION CRITERIA

All randomised controlled trials that involved an intervention described as RMT versus a control group using an alternative intervention, placebo, usual care, or no intervention for people with cervical SCI were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected articles for inclusion, evaluated the methodological quality of the studies, and extracted data. We sought additional information from the trial authors when necessary. We presented results using mean differences (MD) (using post-test scores) and 95% confidence intervals (CI) for outcomes measured using the same scale or standardised mean differences (SMD) and 95% CI for outcomes measured using different scales.

MAIN RESULTS

We included 11 studies with 212 participants with cervical SCI. The meta-analysis revealed a statistically significant effect of RMT for three outcomes: vital capacity (MD mean end point 0.4 L, 95% CI 0.12 to 0.69), maximal inspiratory pressure (MD mean end point 10.50 cm/H2O, 95% CI 3.42 to 17.57), and maximal expiratory pressure (MD mean end point 10.31 cm/H2O, 95% CI 2.80 to 17.82). There was no effect on forced expiratory volume in one second or dyspnoea. We could not combine the results from quality of life assessment tools from three studies for meta-analysis. Respiratory complication outcomes were infrequently reported and thus we could not include them in the meta-analysis. Instead, we described the results narratively. We identified no adverse effects as a result of RMT in cervical SCI.

AUTHORS' CONCLUSIONS

In spite of the relatively small number of studies included in this review, meta-analysis of the pooled data indicates that RMT is effective for increasing respiratory muscle strength and perhaps also lung volumes for people with cervical SCI. Further research is needed on functional outcomes following RMT, such as dyspnoea, cough efficacy, respiratory complications, hospital admissions, and quality of life. In addition, longer-term studies are needed to ascertain optimal dosage and determine any carryover effects of RMT on respiratory function, quality of life, respiratory morbidity, and mortality.

Development of new measurement system of thoracic excursion with biofeedback: reliability and validity

Background

Respiratory rehabilitation reduces breathlessness from patient with respiratory dysfunction. Chest expansion score, which represents the circumference magnitude of the thoracic cage, is used for a target when treating patients with respiratory disease. However, it is often difficult for patients to understand the changes in the respiratory status and be motivated for therapy continuously. We developed a new measurement system with biofeedback named BREATH which shows chest expansion scores in real time. The purpose of this study was to determine the reliability and validity of the novel system in advance of clinical application.

Methods

Three evaluators measured chest expansion in 33 healthy individuals using tape measure, which is used for the measurement traditionally, and BREATH. The wire for BREATH system was threaded over the thoracic continuously and the data was recorded automatically; whereas the tape was winded and measured each maximal expiration and inspiration timing by evaluator. All participants were performed both measurement simultaneously for three times during deep breath. In this study, we studied chest expansion score without using biofeedback data of BREATH to check the validity of the result. To confirm intra- and inter-evaluator reliability, we computed intra-class correlations (ICCs). We used Pearson’s correlation coefficient to evaluate the validity of measurement result by BREATH with reference to the tape measure results.

Results

The average (standard deviation) chest expansion scores for all, men and women by the tape measure were 5.53 (1.88), 6.40 (1.69) and 5.22 (1.39) cm, respectively, and those by BREATH were 3.89 (2.04), 4.36 (1.83) and 2.89 (1.66) cm, respectively. ICC within and among the three evaluators for BREATH and the tape measure were 0.90-0.94 and 0.85-0.94 and 0.85 and 0.82, respectively. The correlation coefficient between the two methods was 0.76-0.87.

Conclusion

The novel measurement system, BREATH, has high intra- and inter-evaluator reliabilities and validity; therefore it can lead us more effective respiratory exercise. Using its biofeedback data, this system may help patients with respiratory disease to do exercises more efficiently and clinicians to assess the respiratory exercise more accurately.

Integrated approach for in vivo evaluation of respiratory muscles mechanics

The respiratory muscles constitute the respiratory pump, which determines the efficacy of ventilation. Any functional disorder in their performance may cause insufficient ventilation. This study was designed to quantitatively explore the relative contribution of major groups of respiratory muscles to global lung ventilation throughout a range of maneuvers in healthy subjects. A computerized experimental system was developed for simultaneous noninvasive measurement of inspired/expired airflow, mouth pressure and up to 8 channels of EMG surface signals from major respiratory muscles which are located near the skin (e.g., sternomastoid, external intercostal, rectus abdominis and external oblique) during various respiratory maneuvers. Lung volumes values were calculated by integration of airflow data. Hill's muscle model was utilized to calculate the forces generated by the muscles from the acquired EMG data. Analysis of EMG measurements and respiratory muscles forces revealed the following characteristics: (a) muscle activity increased with increased breathing effort, (b) inspiratory muscles contributed to inspiration even at relatively low flow rates, while expiratory muscles are recruited at higher flow rates, (c) the forces generated by the muscle depended on the muscle properties as well as on their EMG performance and (d) the pattern of the muscle's force curves varied between subjects, but were generally consistent for the same subject regardless of breathing effort.

Respiratory muscle training for tetraplegic patients: A literature review

This paper reviews the evidence concerning the effectiveness of respiratory muscle training for tetraplegic patients. While respiratory muscle strength/endurance and/or pulmonary function have been shown to improve after inspiratory muscle training, a lack of controlled studies means it is not possible to exclude spontaneous recovery from being responsible for the improvements seen. It is not known if inspiratory muscle training improves quality of life or decreases morbidity. There are limited data which suggest that, for ventilator dependent tetraplegics, strengthening the muscles of the neck and upper thorax may improve vital capacity and allow limited ventilator-free time. The effectiveness of other techniques such as glossopharyngeal breathing, expiratory muscle training and exercise as methods of improving respiratory muscle strength/endurance is unknown.

Influence of thoracoabdominal pattern of breathing on respiratory resistance

The purpose of this study was to test the hypothesis that voluntary changes in thoracoabdominal pattern of breathing may increase total respiratory resistance. Thirty-one normal subjects were asked to control their thoracoabdominal pattern of breathing by using a visual feedback. Thoracic and abdominal volume changes were measured by inductance plethysmography. Respiratory resistance and elastance were measured by forced oscillometry. The mean (+/-SD) percent thoracic contributions to tidal volume during thoracic or abdominal breathing were 75 (+/-11) and 25% (+/-9), respectively. These changes induced small but significant increases in resistance (P < 0.005) and elastance (P < 0.002). The increased resistance was observed in 22 subjects for thoracic breathing (P < 0.016) and in 21 subjects for abdominal breathing (P < 0.043). The mean value (+/-SD) of individual increases in resistance during thoracic or abdominal breathing, compared with normal breathing, were 9.2 +/- 17.5 and 9.4 +/- 19.9%, respectively. The fact that departing from spontaneous pattern increases respiratory resistance is consistent with the notion that breathing pattern is optimally adjusted on the basis of mechanical criteria.

Effects of abdominal and thoracic breathing upon multiple-site electromyography and peripheral skin temperature

Peripheral finger temperature, frontalis and upper trapezius EMG, and self-report of arousal were assessed for four subjects during abdominal and thoracic breathing in a single-subject reversal design. Two subjects displayed significant differences between abdominal and thoracic breathing conditions; one for frontalis EMG, trapezius EMG, and self-report of arousal and one for trapezius EMG. Two subjects showed no significant effects. All subjects reached performance criteria during training sessions. Abdominal breathing performance during reversals was 100% and 92% of sampled breath cycles for the two subjects who showed significant change, and 65% and 42% for the two subjects who showed none. Methodological issues for measurement of breathing patterns and peripheral skin temperature are discussed.