Too Much Oxygen Potentially Risky for Chronic Lung Patients

For Immediate release

Landmark Kiwi Research Shows Too Much Oxygen is Potentially Risky for Chronic Lung Patients

Ground-breaking research looks set to change the way patients who are acutely unwell with a chronic and common lung disease are treated in hospital.

An estimated 200,000 New Zealanders suffer from Chronic Obstructive Pulmonary Disease (COPD), a smoking-related illness which damages the lungs beyond repair. COPD is the clinical term for both emphysema and chronic bronchitis. Over 12,000 patients are hospitalised with acute COPD every year, and are often admitted in distress, struggling to breathe. It is the fourth most common cause of death in New Zealand behind cancer, heart disease and stroke.

Until now, it’s been common practice in hospitals worldwide to administer nebuliser drugs to millions of acutely ill COPD patients using high flow oxygen as a means of driving the treatment into the lungs where it’s needed. The pervasive view has been that high flow oxygen-driven nebulisation is the best treatment and preferable to the use of high flow air.

However a landmark new study conducted by a team at the Medical Research Institute of New Zealand (MRINZ) shows, for the first time, that nebulisation using oxygen as the driving gas is potentially dangerous for acutely unwell COPD patients compared with room air.

“Until now it has been thought that oxygen as a means of delivering vital nebuliser therapy has been safe for patients hospitalised with acute flare-ups” says study author and MRINZ Director Professor Richard Beasley. “This study however shows that high flow oxygen to nebulise the medication can actually cause harm. Our results show excessive oxygen actually reduces ventilation, and, in some patients, causes a substantial build-up of carbon dioxide to risky levels” he says.

The Health Research Council-funded study, just published in the international journal BMC Pulmonary Medicine, followed 90 patients who presented to Wellington Hospital with acute COPD in 2015/2016. Participants were randomised to receive salbutamol nebulisers, driven by either oxygen or air. (Oxygen-driven nebulisation delivers 100% oxygen at high flow as opposed to room air nebulisation which delivers only 21% oxygen at high flow). The results showed that four in every ten (40%) patients given oxygen-driven nebuliser treatment exhibited a significant increase in levels of carbon dioxide in the blood as opposed to none (0%) whose treatment was driven by air alone. Very high levels of carbon dioxide are a cause for concern as they can cause patients to fall into a coma and potentially die. This risk varies from patient to patient.

“The results of this study have immediate and important implications for health-care providers, policymakers and researchers” says Professor Beasley. “Prior practice guidelines and medical directives on the preferred driving gas for nebulisers have been inconsistent. Our results provide much-needed clarification by showing that administering bronchodilators via oxygen driven nebulisers is potentially harmful, and that either air-driven nebulisers or simple inhalers are the preferred method of delivery.”

Waikato DHB Respiratory Physician Professor Bob Hancox agrees.

“As a result of this study guidelines should be reviewed to recommend that bronchodilator treatment is provided with air rather than oxygen and that if patients do need additional oxygen, this should be provided separately in a controlled manner” he says. “We need to ensure we provide the correct dose of oxygen adjusted to the patient’s needs”.

The HRC also welcomes the study findings.

“ COPD exacerbations are distressing and can be terrifying for the person with the disease and their loved ones” says HRC Chief Executive Professor Kathryn McPherson. “These results provide solid evidence for safer treatment for people when they are acutely unwell. This matters enormously given that 12,000 New Zealanders with severe COPD are estimated to need hospitalisation in any one year”.

The study is the latest in a longstanding programme of MRINZ research examining the optimal use of oxygen across a wide range of acute and stable illnesses. The Institute’s next HRC-backed study aims to establish just how much oxygen is safe or potentially harmful for adults receiving life support in hospital intensive care units. This study has just completed enrolling the 1000 patients required to proceed.

What is COPD?

• It is the umbrella disease covering both emphysema and chronic bronchitis. It is a chronic lung disease, primarily caused by smoking, which causes the airways and tissues of the lungs to become permanently damaged, making it hard to breathe.

• Although affecting around 200,000 New Zealanders, many are unaware they have it until the disease becomes quite advanced, limiting the effectiveness of treatment.

• Symptoms include breathlessness, chest tightness, a cough with mucous, tiredness and weight loss.

• The best treatment for COPD is immediate smoking cessation. Symptoms can be managed with medications such as bronchodilators, inhaled and oral steroids.

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