THE STRAITS TIMES
PHOTO: ST FILE
The way the Hemolung Respiratory Assist System works is similar to a kidney
dialysis machine (above). It collects the patient’s blood, removes carbon dioxide
and then returns the blood back to the patient.
‘Dialysis’ for
the lungs
New machine removes
dangerous build-up of
carbon dioxide in
patients’ blood.
Joan Chew reports
A
new machine is being
tried out at a hospital
here, which could save
the lives of patients on
mechanical ventilators.
The ventilator that
helps patients breathe, thus keeping
them alive, is also the device that
could make them worse.
The machine is needed for
patients who have moderate to
severe acute respiratory distress
syndrome, a life-threatening
condition which prevents enough
oxygen from reaching the lungs.
But the ventilator changes the
way air is delivered to the lungs.
It pushes air into a patient’s
airway, instead of relying on air
being sucked in through breathing,
said Dr Matthew Cove, an intensivist
and consultant at the division of
respiratory and critical care medicine
at National University Hospital
(NUH).
The airway then reacts to the
increased pressure by releasing
inflammatory substances that further
injure the lungs and worsen acute
respiratory distress syndrome.
Up to half of these patients can
die when this happens.
Doctors now reduce the amount
of air that is pushed into the lungs,
called the tidal volume, but this has
created other problems.
As less carbon dioxide is removed
through the ventilator with a lower
tidal volume, it accumulates in the
patient’s blood, turning it acidic.
High levels of carbon dioxide in
the blood causes hypercapnia, which
impairs the function of the heart and
puts a patient at risk of a cardiac
arrest. It also appears to slow down
or impair bacterial killing, preventing
patients from fighting infections
properly.
Dr Cove and his team are now
testing a new machine that collects
blood from the body and removes
the carbon dioxide before returning it
back to the patient.
He said it is similar to a dialysis
machine, which takes over the
function of an impaired kidney by
removing toxins from the blood.
The machine, called the
Hemolung Respiratory Assist
System, is easier to operate than
other carbon dioxide-removal
machines, he added.
In the next 11/2 years, up to 50
patients with acute respiratory
distress syndrome who are on
ventilators will be randomly assigned
to either Hemolung or standard care.
Consent for the study will be sought
from their next-of-kin.
Their rate of recovery and number
of days on the ventilator will be
tracked, among other things.
Dr Cove said: “Our goal is to halt
the progression of acute respiratory
distress syndrome and facilitate lung
recovery, while avoiding more
invasive treatments.”
Acute respiratory distress
syndrome affects critically ill
patients and is typically triggered by
pneumonia, sepsis (blood poisoning)
or trauma. Up to 60 in every
100,000 people will be affected,
according to overseas studies.
[email protected]
MAY 21 2015
13