We need oxygen to keep us alive, but what happens when we stop breathing and that oxygen runs out? One cardiologist believes that injecting oxygen into the bloodstream could be the answer.
One of the biggest problems faced by doctors dealing with critically ill patients is how to keep them breathing.
If there’s no oxygen in the blood, oxygen won’t get to the brain, and that’s when cardiac arrests or brain injuries occur.
Luckily, there are machines which help to keep blood oxygenated, but they aren’t always readily available and can also take a considerable amount of time to set up.
But what if doctors were simply able to inject oxygen into the blood? Up until now, restoring the oxygen level of blood by injecting it with oxygen has been out of the question, because the oxygen can form bubbles which can then block blood flow.
However, a recent study conducted by a Boston-based doctor might just be about to change all that.
In 2006, Dr John Kheir, a cardiologist based at Boston Children’s Hospital’s cardiology department, was treating a young girl whose lungs had been seriously damaged by pneumonia.
Her lungs had subsequently filled with blood, but by the time the doctors had set up the heart-lung bypass machine, she’d suffered severe brain damage due to the lack of oxygen.
‘Despite our efforts, she suffered severe brain injury and died,’ recalled Dr Kheir.
‘I was frustrated that all we had needed to do was to provide oxygen to her blood for just a few minutes and that could have prevented her death.’
He added: ‘Many patients die every year from critically low oxygen levels. The typical treatment for these patients involves increasing the amount of oxygen they are breathing by the placement of a breathing tube, or by using a heart-lung bypass machine.
‘The problem is that these measures take time to put into place and during this time low oxygen levels can cause the heart to function poorly, lowering blood pressure and causing cardiac arrest or brain injury.’
Dr Kheir then embarked on a study which would prove oxygen can be injected into bloodstreams without causing blockages, through enclosing tiny bubbles of oxygen within a shell-like structure.
Key to Dr Kheir’s study were lipids – a group of naturally-occurring molecules which include fats, waxes, sterols and vitamins. The lipids used in Dr Kheir’s study were fats and measured about two to four micrometres (a micrometre is one-thousandth of a millimetre) in size.
The lipid-encased oxygen bubbles were then suspended in a fluid commonly used in transfusions, which could be injected into the bloodstream.
Because such a treatment could only ever be used as a temporary measure – to prevent brain damage, cardiac arrest and therefore keep a patient alive until they can access life-saving equipment – in theory, it could be also be used by ‘first responders’ such as paramedics, in addition to hospital-based medical staff.
‘First responders face challenges that include difficulty in maintaining or obtaining an airway that results in a loss of critical time,’ said Professor John F Beshai, director of pacemaker and defibrillator services at the University of Chicago.
‘Advances in resuscitation that can maintain adequate oxygenation of tissues and organs just long enough to get the patient to a centre where further lifesaving measures can be implemented would be a major breakthrough.’
However, Dr Duncan Young, senior lecturer in anaesthetics at the University of Oxford, is less positive and foresees a possible stumbling block in getting funding for further research when the treatment in question would only ever benefit a small group of people.
He said it could only help those in a situation in which simple measures to maintain blood oxygen levels have failed and who have access to a secondary long term solution such as heart-lung machines or extracorporeal membrane oxygenation (ECMO). This process provides support oxygen through a machine to the heart and lungs when they can no longer function properly.
‘The number of patients this could actually help is very small,’ said Dr Young.
‘This drug could only be used in centres with ECMO, as it wouldn’t keep people alive long enough for transfer to an ECMO centre.
‘However, there are only five ECMO centres in the UK. It would also have to be stable in storage, which would be unlikely, as oxygen is a highly reactive chemical.’
Additionally, the nature of the treatment means that it could only be used in cases where the patient’s blood is still circulating efficiently.
‘Studies in humans were conducted as far back as the 1990s to see if similar agents could reduce the size of heart attacks, but with no real success,’ said Professor John Cleland, from the Department of Cardiology at Hull York Medical School.
‘The bigger issue may be less about whether an oxygenated blood substitute can be created but rather what should it be used for.
‘The patient still needs to have blood circulating around the body for these agents to work and deliver the oxygen.’
However, there’s no denying the importance of Dr Kheir’s study. His peers admit its consequences could be huge if Dr Kheir gets the FDA (US Food and Drug Administration) approval he hopes to apply for in several years’ time.
‘The concept of the therapy seems sound,’ said Allen S Anderson, from the University of Chicago’s Medical Center. ‘While many of the patients would ultimately need ECMO and many centres don’t have this technology, there are some scenarios where the therapy might be useful without the need for ECMO.
‘And for those of us practicing in centres with ECMO – we’ve all had patients in whom it couldn’t be started rapidly enough to prevent brain damage.
Buying 20 to 30 minutes of time could be the difference between life and death.’