Respiratory and Skeletal Muscle

Professor Micheal Polkey - Head of Group

Our group is concerned with the improvement of exercise performance in COPD. Our fundamental philosophy rests on the ‘spiral of disability [1] illustrated.

Based on this concept we believe that there are 4 key areas where science can enhance the quality of life of patients with COPD. Integral to this work is expertise in the measurement of exercise performance both on exercise tests as well as during daily life. These are

1. Reversing quadriceps dysfunction: to address this we have conducted innovative studies to delineate the extent of the problem of skeletal muscle weakness, how best to assess it and its effect on prognosis. We are actively interested in reversing it through pulmonary rehabilitation and eventually through novel pharmacological strategies~to prepare for this we are currently running a biopsy program so that we are well placed to validate targets
2. Countering anaerobic metabolism: to address this we are currently building on previous work [2] to see whether non-invasive ventilation can enhance exercise performance in COPD and thus be a useful adjunct to pulmonary rehabilitation
3. Countering hypoxia: Low oxygen levels greatly reduce quality of life for patients with COPD. One cause of a low oxygen level is persistence of a foetal right to left connection, a patent foramen ovale. Current studies are aimed at establishing how common and how important this problem is in COPD.
4. Reducing ventilatory requirements by improving lung mechanics: We are hopeful that novel mechanical strategies can achieve this aim so this remains an active area for us. We were the first to use one way valves in emphysema [3] and this described our initial experience with trans thoracic pneumonostomy [4]

The group is also expert in the assessment of respiratory muscles in diverse clinical situations having described many of the original techniques (e.g [5-7]). We are one of the last centres worldwide who remain able to assess respiratory muscle and pulmonary mechanics using catheters placed in the oesophagus and stomach.

Current  projects in the group:

• Understanding the molecular basis for quadriceps weakness in COPD
• What causes exercise limitation in patients with COPD?

References

1. Polkey MI, Moxham J. Attacking the disease spiral in chronic obstructive pulmonary disease. Clin Med 2006: 6(2): 190-196.

2. Hawkins P, Johnson LC, Nikoletou D, Hamnegard CH, Sherwood R, Polkey MI, Moxham J. Proportional assist ventilation as an aid to exercise training in severe chronic obstructive pulmonary disease. Thorax 2002: 57(10): 853-859.

3. Hopkinson NS, Toma TP, Hansell DM, Goldstraw P, Moxham J, Geddes DM, Polkey MI. Effect of bronchoscopic lung volume reduction on dynamic hyperinflation and exercise in emphysema. Am J Respir Crit Care Med 2005: 171(5): 453-460.

4. Moore AJ, Cetti E, Haj-Yahia S, Carby M, Bjorling G, Karlsson S, Shah P, Goldstraw P, Moxham J, Jordan S, Polkey MI. Unilateral extrapulmonary airway bypass in advanced emphysema. Ann Thorac Surg 2010: 89(3): 899-906, 906 e891-892.

5. Laroche CM, Mier AK, Moxham J, Green M. The value of sniff esophageal pressures in the assessment of global inspiratory muscle strength. Am Rev Respir Dis 1988: 138: 598-603.

6. Mills GH, Kyroussis D, Hamnegard CH, Polkey MI, Green M, Moxham J. Bilateral magnetic stimulation of the phrenic nerves from an anterolateral approach. Am J Respir Crit Care Med 1996: 154(4 Pt 1): 1099-1105.

7. Luo YM, Moxham J, Polkey MI. Diaphragm electromyography using an oesophageal catheter: current concepts. Clin Sci (Lond) 2008: 115(8): 233-244.