An extended interview with Dr. Alfred P Bowles, Jr., Chairman of Neuroscience and Neurosurgery, on Hypothermia Treatment for Brain and Spine Injuries
Q. So today we are going to talk about how you’re using the hypothermia or cooling the body for brain injuries.
A. Well we are using hypothermia for brain injuries at our institution, and we developed a comprehensive traumatic brain injury protocol that we use universally, hospital wide which we collaborate with our trauma service which we’re implementing an aggressive form of therapy for patients with traumatic brain injury. It focuses on cerebral perfusion pressure, ICP, partial brain tissue oxygen concentration and the real concept is that we’re trying to prevent secondary injury. When you have a traumatic brain injury, you can have a primary injury which occurs at the impact but then there is this generation of secondary injury. You have sort of injured brain cells that have a potential to recover or they have a potential to worsen and they can recruit other cells to become damaged to, and it’s caused by a number of molecular and cellular mechanisms and what we try to do with our traumatic brain injury protocol, we try to optimize an environment for those damaged, injured or recuperating brain cells to recover and part of the protocol is to maximize brain temperature. Obviously if the temperature is too high, metabolic activity would be too high or be higher and requirements would be much too much for an injured brain and what we find is that as we’re trying to control various parameters as we monitor the recovery of the brain, when we lower the temperature to 36 to 37 degrees, that gives us a beneficial effect for brain recovery and we have a lot of sophisticated delivery systems in order to control brain temperature.
Q. How do you control brain temperature?
A. Well, you know, initially we may use cooling blankets. Sometimes we use IV bags that are cooled and put them on the side of the patients head and then we can do them in a controlled setting with these delivery systems where often times either veins or arteries are cannulated and cooled saline is administered in a controlled fashion in which you can actually regulate and monitor just the, how cold the body is and you can control the rate of descent of the temperature that way too.
Q. So to cool the brain are you actually cooling down, do you have to cool down the whole body?
A. Yes you do.
Q. So do you use the Arctic Sun?
A. That’s right. Absolutely, absolutely.
Q. And so the average person at home watching this could understand, cooling the brain you’re actually I guess slowing it down so it’s not working so hard.
A. Well you’re slowing down the metabolic requirements. So if the, if the brain needs more energy, if the brain needs more oxygen, if it doesn’t have those, the oxygen, the blood flow, and the energy then it won’t survive, but if you reduce their needs then it has a better chance to survive. It has a better chance to recover and that’s what, that’s how lowering the temperature theoretically can be a neuroprotector for the injured brain.
Q. Are you excited by this, because I would think that this could really have some big implications down the road?
A. Oh yeah, it’s very exciting. I think, you know, anything and everything that we study to help protect the brain, to help the brain to recover, to help protect the spinal cord, to help the spinal cord to recover, I think it’s very, very exciting and it’s very, very interesting. I think we are making good progress.
Q. So we have a protocol here at Memorial for cardiac arrest patients where they use the Arctic Sun and cool the body and a protocol in place for brain. Spine is a little, something coming down the road, I mean are there implications that this will work for the spine as well?
A. Absolutely, absolutely. When we talk about it’s the concept of hypothermia for the brain and spinal cord, now that’s not a new concept, and it’s been looked at and studied probably since the 1960s. With studies for people probably in the 70s and 80s. Well the enthusiasm has waxed and waned because there are certain side effects that can occur when the temperature of the body is brought down too low. Typically when it’s below 92 degrees Fahrenheit or 33 degrees Celsius, there are some side effects which can occur such as cardiac arrhythmias, infection and bleeding disorders. Now there’s been a resurgence in the enthusiasm for the study of hypothermia particularly for spinal cord injury which has been focused through a lot of work done through Dr. John Barth, Chairman of Neurosurgery at Miami through the Miami Project to Cure Paralysis, and they’ve done a lot of research trying to look at ways to allow, to either protect the spinal cord or to allow it to recover and what they found is the real premise for hypothermia is that if you are able to, if you are able to cool down the spinal cord soon within injury the hypothermia can confer neuroprotective mechanisms and it can slow down the damaging inflammatory processes which typically occur right after injury and the concept is if you have a spinal cord injury patient you implement and you infuse cold saline immediately within minutes to hours. You know, in the case of our football player who was injured, the, his attending surgeon was right on the scene and as they were in route to the hospital ice saline was given intravenously through the vein and an operation was performed. Then after the operation performed, they used this controlled mechanism much like the Arctic Circle where a catheter was placed into the femoral artery and iced saline is given in a controlled fashion that can be monitored and regulated so the temperature can be brought down very slowly and controlled and you know exactly what you are doing and typically they would keep that lowered temperature down to a level of about 33 degrees Celsius and they would keep that temperature that low for 48 hours and then they would, after 48 hours they would raise the temperature about 1 degree every eight hours. And, you know, the whole concept is is that they’re minimizing the secondary injury or the inflammatory processes, secondary damage that can be so damaging to the spinal cord that’s been initially injured. Now, you got to remember, this is all experimental. It’s not standard of care and it can be done and only in a very, very controlled setting like the Miami Project and, you know, now I am just at the beginning phases to try to bring that form of therapy to our institution as well but, you know, it has to be done in a very controlled supervised and regulated environment.
Q. You talk about the inflammatory so basically when you have an injury in spinal cord you are going to have swelling and cooling helps stop some of that, but when you have a regular injury it swells a little and then it goes down on its own anyway eventually but as the spinal cord swells is it doing more damage?
A. Well the spinal cord swells but you got to remember the, the inflammatory cascade occurs at a cellular molecular level. With that injury there is loss of perfusion, loss of oxygenation. There’s a degree of acidosis so the cells become injured. There’s also been some studies that show that when you have a, when the spinal cord is damaged, right at the site of damage to the spinal cord, Schwann cells migrate to the damaged cell and as they migrate to the damaged area they release this inhibitory protein which prevents recovery and regeneration or --- and prevents recovery and it maintains the damage. There has also been some studies that show that when you have a spinal cord injury it stimulates cell programmed death or apoptosis. There also has been a number of studies I think very, very interesting that show that when you have an area of the spinal cord that’s completely damaged and it can’t function anymore, circuits can reroute around it. Within the spinal cord you have, you have this arborization of connections around it so that you can have a fair amount of recovery or regeneration of the deficit. That’s called CNS or spinal cord plasticity. So, you know, it’s all very interesting but the bottom line is there’s a cascade of inflammatory processes that occur at many different levels. In the brain, a lot of times it’s the release of a lot of exotoxic factors and an intercellular release of calcium that can be very damaging. So all these things help minimize the inflammatory processes than can occur. You know, each step that it may minimize we don’t know, but we do know that there are beneficial effects.
Q. Okay. I guess the brain, the spine, and the cardiac arrest too, I guess you have such a narrow window of opportunity to make a difference.
A. That’s correct. You know for a spinal cord injury we, we don’t know really what that, what that optimal window is. Do you have to do it within five minutes, do you have to do it within 50 minutes? You know, our football player who got injured, he was lucky because it was instituted within 15 minutes. Maybe that had a demonstrable affect but we don’t know, it needs to be within 15 minutes or can it be within an hour or two once we bring the patient to the hospital. We don’t know that and those are things that need to be worked on. I think we do have sort of a, through the Miami Project, a good informational base that the lower temperature should be maintained for 48 hours. I think that’s pretty well, been pretty well looked at.
Q. I’m sure you’ve seen countless lives in your field that have just been changed. You know, people that have gone from being active and in an accident or something and they’re quadriplegic and, I mean, so it must be, just the thought of what lies ahead must be so exciting for you.
A. I think it’s very exciting. You know, the things that we may be, the things that we’re able to do now that we weren’t able to do a few years ago and the things that potentially we’ll be able to do later, it’s really exciting. You know, sci-, you know, medicine, particularly neuroscience and neurosurgery, especially with the implementation of new technology, results improve or outcomes improve by leaps and bounds and it’s really exciting. You know, what in neurosurgery we’re able to do now is so much different than what we were able to do 10 years ago and especially what we were able to do 20 years ago. A lot of it, you know, it has to do with the fact that we’re just learning more, understanding more. That’s the whole evolution of how we learn and, how we learn and how the science of neuroscience grows, but a lot of it has to do with the implementation of new technology.