Endobronchial coils for severe emphysema are effective up to 12 months following treatment: medium term and cross-over results from a randomised controlled trial.

BACKGROUND: There is a clinical need for therapeutic options to reduce hyperinflation associated with severe emphysema. Endobronchial Coils (coils) are nitinol devices implanted bronchoscopically under fluoroscopic guidance to re-tension the lung. We report the medium term effectiveness and safety of coils in a study of patients with emphysema. METHODS: Forty five subjects with severe airflow obstruction and hyperinflation received bilateral sequential treatment with coils (30 day interval between treatments) as part of a randomised controlled trial with a primary endpoint 90 days after the final treatment (Clinicaltrials.gov NCT01334307). Further assessments were made at 180 and 360 days and in this study the primary outcome was the effect of coil treatment on the St. George's Respiratory Questionnaire (SGRQ) 360 days following treatment. RESULTS: At 360 days following treatment, there was an improvement in the SGRQ score of -6.1±14.0 points (p = 0.01) compared to baseline. Improvements in secondary outcomes were seen with increases in forced expiratory volume in the first second of 8.9 ±22.2% (p = 0.002) and 6-minute walking distance of 34.1±52.4m (p = 0.003). The safety profile was acceptable out to 360 days post-treatment. CONCLUSIONS: Statistically and clinically meaningful benefits in quality of life, exercise capacity and pulmonary function in patients treated with coils are sustained twelve months after treatment. TRIAL REGISTRATION INFORMATION: Clinicaltrials.gov NCT01334307.

Endobronchial coils for the treatment of severe emphysema with hyperinflation (RESET): a randomised controlled trial.

BACKGROUND: Few treatment options exist for patients with severe emphysema. We assessed the clinical benefits and safety of lung volume reduction coils (LVRCs) for the treatment of patients with severe emphysema with hyperinflation. METHODS: In a randomised study, we recruited patients with severe emphysema (aged ≥35 years) from three centres in the UK. Using a computer-generated randomisation sequence, we randomly allocated patients in a one-to-one ratio (block sizes of four and stratified by centre) to either LVRC treatment (treatment group) or best medical care (usual care group). The primary endpoint was the difference in response in the St George's Respiratory Questionnaire (SGRQ) between treatment and usual care groups at 90 days after final treatment (by intention-to-treat analysis). The trial is registered with ClinicalTrials.gov, number NCT01334307. FINDINGS: Between Jan 27, 2010, to Oct 25, 2011, we recruited and randomly allocated 47 patients: 23 to treatment and 24 to usual care (23 patients in each group were included in the intention-to-treat analysis). SGRQ response at 90 days after final treatment was greater in the treatment group than it was in the usual care group (between-group difference in change from baseline -8·36 points [95% CI -16·24 to -0·47]; p=0·04). We detected no between-group difference in serious adverse events. INTERPRETATION: Our findings suggest that treatment with endobronchial coils can improve quality of life for patients with severe emphysema and hyperinflation. FUNDING: PneumRx.

Exercise-induced depression of the diaphragm motor evoked potential is not affected by non-invasive ventilation.

Whole body exercise is followed by a depression of the diaphragm motor evoked potential (MEP). It is unknown whether the change is due to diaphragm activity or whole body exercise. To test the hypothesis that exercise-induced MEP depression was related to diaphragm activity, we performed two experiments. The first examined the effect of whole body exercise, performed with and without the use of non-invasive ventilation (NIV). NIV resulted in significant unloading of the diaphragm (pressure time product 101+/-68 cm H(2)O/s/min versus 278+/-95 cm H(2)O/s/min, p<0.001). Both conditions produced significant MEP depression compared to the control condition (% drop at 5 min, after exercise and exercise with NIV: 29 and 34%, p=0.77). Study 2 compared exercise with isocapnic hyperventilation. At 20 min the MEP had fallen by 29% in the exercise session versus 5% with hyperventilation (p=0.098). We conclude that the work of breathing during whole body exercise is not the primary driver of exercise-induced diaphragm MEP depression.

Does symptom-limited cycle exercise cause low frequency diaphragm fatigue in patients with heart failure?

BACKGROUND: Reduced diaphragm contractility occurs in some healthy subjects when they exercise to exhaustion. This indicates low frequency fatigue, which may contribute to task failure. We hypothesised that patients with congestive heart failure (CHF) might be especially vulnerable to the development of low frequency diaphragm fatigue after exhaustive exercise. AIMS: To study the effect of exhaustive incremental cycle exercise on diaphragm contractility in patients with CHF. METHODS: 12 patients with CHF with an ejection fraction of 36.5 +/- 7.3% and 12 healthy age-matched control subjects performed an incremental cycle test to exhaustion. The unpotentiated twitch transdiaphragmatic pressure (twitch Pdi) in response to bilateral anterolateral magnetic phrenic nerve stimulation (BAMPS) was measured before and after exercise. RESULTS: Twitch Pdi at baseline was 20.2 +/- 6.7 cm H2O in the CHF group and 20.3 +/- .3 cm H2O in the controls (p = 0.957). 25 and 35 min post exercise the values were 19.9+/-5.4 and 20.0+/-5.1 cm H2O in the CHF group and 20.6 +/- 4.3 and 21.2 +/- 3.4 cm H2O in the control group; neither change was significant (F(2,27) = 0.007, p = 0.993; F(2,33) = 0.144, p = 0.866, respectively). CONCLUSION: When patients with CHF cycle to exhaustion, low frequency fatigue of the diaphragm does not occur, and this is unlikely to be an important factor limiting exercise capacity of such patients.

Motor control of the costal and crural diaphragm--insights from transcranial magnetic stimulation in man.

The costal and crural parts of the diaphragm differ in their embryological development and physiological function. It is not known if this is reflected in differences in their motor cortical representation. We compared the response of the costal and crural diaphragms using varying intensities of transcranial magnetic stimulation of the motor cortex at rest and during submaximal and maximal inspiratory efforts. The costal and crural motor evoked potential recruitment curves during submaximal inspiratory efforts were similar. The response to stimulation before, during and at 10 and 30 min after 44 consecutive maximal inspiratory efforts was also the same. Using paired stimulations to investigate intra-cortical facilitatory and inhibitory circuits we found no difference between the costal and crural response with varying interstimulus intervals, or when conditioning and test stimulus intensity were varied. We conclude that supraspinal control of the costal and crural diaphragm is identical during inspiratory tasks.

Corticospinal control of respiratory muscles in chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) face an increased respiratory load and in consequence have an elevated respiratory drive. We used transcranial magnetic stimulation (TMS) to investigate associated changes in corticospinal excitability both at rest and during voluntary facilitation at different levels of inspiratory effort. Diaphragm and abdominal motor thresholds were significantly lower in COPD than healthy controls, but the quadriceps response was the same. In patients there was a significant increase in diaphragm response from rest during 20% inspiratory efforts but no further increase with greater efforts. In controls there was a further stepwise increase at 40% and 60% of inspiratory effort. The cortical silent period was significantly shorter in COPD. Using paired stimulation to study intracortical inhibitory and excitatory circuits we found significantly less excitability of intracortical facilitatory circuits in patients at long (>7 ms) interstimulus intervals. These results suggest that there is a ceiling effect in motor control output to the respiratory muscles of patients with COPD.

Depression of diaphragm motor cortex excitability during mechanical ventilation.

The effect of mechanical ventilation on the diaphragm motor cortex remains unknown. We assessed the effect of mechanical ventilation on diaphragm motor cortex excitability by measuring the costal and crural diaphragm motor-evoked potential (MEP) elicited by single and paired transcranial magnetic stimulation. In six healthy subjects, MEP recruitment curves of the costal and crural diaphragms were assessed at relaxed end expiration during spontaneous breathing [baseline tidal volume (Vt(baseline))] and isocapnic volume cycled ventilation delivered noninvasively (NIV) at three different levels of tidal volume (Vt(baseline), Vt(baseline) + 5 ml/kg liters, and Vt(baseline) + 10 ml/kg liters). The costal and crural diaphragm response to peripheral stimulation of the right phrenic nerve was not reduced by NIV. NIV reduced the costal and crural MEP amplitude during NIV (P < 0.0001) with the maximal reduction at Vt(baseline) + 5 ml/kg. Response to paired TMS showed that NIV (Vt(baseline) + 5 ml/kg) significantly increased the sensitivity of the cortical motoneurons to facilitatory (>9 ms) interstimulus intervals (P = 0.002), suggesting that the diaphragm MEP amplitude depression during NIV is related to neuromechanical inhibition at the level of motor cortex. Our results demonstrate that mechanical ventilation directly inhibits central projections to the diaphragm.