Valves May Allow Patients with Severe Emphysema to Breathe Easier

The umbrella-shaped Spiration IBV® Valve.

Photo courtesy of Spiration, Inc.

Clinical trials of patients with emphysema are investigating the effectiveness of small valves, inserted into the large airways of the lung, to improve breathing.

Emphysema

Primarily caused by smoking, emphysema is an irreversible and progressive lung disease. Damaged lung tissue crowds healthier lung tissue, and patients struggle to draw a breath. Emphysema is part of a lung disease known as Chronic Obstructive Pulmonary Disease (COPD), which affects an estimated 714,000 Canadians.[1]

How It Works

The minimally invasive procedure is designed to mimic the results obtained through lung volume reduction surgery. The one-way valves are inserted into the lungs, via the throat, using a flexible instrument called a bronchoscope. The valves conform to fit the airway, allowing normal clearance of air and mucous, but preventing air from flowing into poorly functioning areas of the lung. In theory, this causes diseased areas of the lung to collapse and allows healthier areas to expand, thus increasing oxygen exchange.

On average, five valves are implanted per patient, and the procedure takes about one hour. Although the implants are meant to be permanent, the valves can be repositioned or removed as needed.

In clinical studies, valves were typically inserted under general anesthetic,[2,3] but experts suggest that the procedure could be done with intravenous sedation and local anesthetic, thus reducing hospital admissions.[3,4]

An Alternative to Major Surgery

Lung valves could provide an alternative to lung volume reduction surgery, which removes non-functional areas of the lung. Complications with this invasive surgery are common, recovery is lengthy, costs to the health care system are high, and many patients are not surgical candidates.[3]

Regulatory Status

There are two lung valve manufacturers: Emphasys Medical, Inc. (Redwood City, CA) and Spiration, Inc. (Redmond, WA). Currently, both valves are limited to investigational use in research trials in Canada and the United States.[5,6]

Evidence

A multi-centre retrospective case series reported improvements in lung function and exercise tolerance 90 days after surgery in 98 patients who received 396 Emphasys valves. Forced expiratory volume in one second (FEV1) increased by 11% (p=0.007), and the 6-minute walk distance by 23% (p<0.001). Serious complications occurred in eight patients, including one death.[2]

A multi-centre prospective case series of 30 patients reported improvements in quality of life, but not in lung function or exercise tolerance, six months after placement of 194 Spiration IBV® Valves. Adverse events, possibly due to the valves, occurred in 17 patients, and ultimately seven patients had their valves removed.[3]

Next Steps

A randomized controlled trial is underway with the Emphasys valve,[6] as is a randomized trial with the Spiration valve.[5]

Cost

Cost information is unavailable.

References

[1] Chronic obstructive pulmonary disease (COPD): backgrounder. Ottawa: The Lung Association; 2006. Available: http://www.lung.ca/_resources/COPD_Backgrounder_2006.doc

[2] Wan IY, et al. Chest 2006;129(3):518-26.

[3] Wood DE, et al. J Thoracic Cardiovasc Surg 2007;133(1):65-73.

[4] Cetti EJ, et al. Clin Pulm Med 2006;13(5):263-70.

[5] Spiration [Web page]. In: Spiration, Inc. Redmond (WA): Spiration, Inc.; 2007. Available: http://www.spirationinc.com/

[6] Emphasys [Web page]. In: Emphasys Medical, Inc. Redwood City (CA): Emphasys Medical, Inc.; 2007. Available: http://www.emphasysmedical.com/wt/home