2010-10-19 11:58:55 UTC
"After more than 200 years of haphazard use"
Change in how paramedics use oxygen could reduce deaths
Published: Tuesday, October 19, 2010 - 05:02 in Health & Medicine
A change to the way paramedics use oxygen when treating patients with
chronic lung disease could cut the death rate in these cases by up to
78%, according to a new study published on bmj.com today. Researchers
based in Australia found the risk of death in patients with chronic
obstructive pulmonary disease (COPD) was significantly reduced by
using titrated (controlled) oxygen therapy instead of the current
common approach of high concentration oxygen.
High concentration oxygen is used routinely by many paramedics in
emergency situations for patients with acute breathlessness caused by
episodes of COPD, a condition that affects over 200 million people
across the world.
However, giving high concentration oxygen to patients with severe lung
disease can lead to a build up of carbon dioxide in the blood, which
can induce respiratory failure.
Hospital audits have also shown an association between using high
concentration oxygen and adverse outcomes such as an increase in
mortality, length of hospital stay, need for ventilation and admission
to high dependency units.
For these reasons, the British Thoracic Society together with 21 other
UK Colleges and Societies produced a guideline in 2008 which
recommended that oxygen therapy for patients with COPD should be
titrated to achieve a blood oxygen saturation of 88-92% compared with
a target saturation range of 94-98% for most other medical
emergencies. This guidance was implemented by the UK ambulance service
Researchers from Tasmania carried out a study involving 405 patients
aged 35 and over who were treated by 62 paramedics from the Tasmanian
Ambulance Service and transported to a local hospital.
The participants were split into two groups – one group (226) was
treated with the standard high concentration oxygen approach and the
other (179) with titrated oxygen therapy – and data collected over a
13-month period between 2006 and 2007.
A confirmed COPD subgroup was identified retrospectively as those
patients with a definite diagnosis of COPD during the study and this
included 214 patients, 117 of whom were treated using high
concentration oxygen and 97 with titrated oxygen with a target range
Results showed significant differences in outcomes, depending on which
approach was used.
Overall mortality was 9% (21 deaths) in the high concentration oxygen
group and 4% (7 deaths) in the titrated oxygen group. This difference
was more pronounced in the confirmed COPD subgroup for which there was
a 9% (11 deaths) mortality rate in the high concentration group
compared with a 2% mortality rate (2 deaths) in the titrated group.
Overall, titrated oxygen therapy reduced the risk of death from
respiratory failure by 58% for all patients and 78% for confirmed COPD
patients compared to high concentration oxygen therapy.
Patients who received high concentration oxygen were also
significantly more likely to develop respiratory acidosis (a condition
in which decreased respiration causes increased blood carbon dioxide
and decreased pH) or hypercapnia, when there is too much carbon
dioxide in the blood.
The researchers conclude: "Our findings provide the first high quality
evidence from a randomised controlled trial for the development of
universal guidelines and support the British Thoracic Society's recent
guidelines on acute oxygen treatment, which recommend that oxygen
should be administered only at concentrations sufficient to maintain
adequate oxygen saturations."
In an accompanying editorial, senior doctors Ronan O'Driscoll and
Richard Beasley warn that routine use of high concentration oxygen may
also be harmful in several other medical emergencies, including heart
attack and stroke."
They conclude: "After more than 200 years of haphazard use, it should
be recognised that oxygen should be prescribed for defined indications
in which its benefits outweigh its risks and that the patient's
response must be monitored."
Source: BMJ-British Medical Journal
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