Can we adapt the strategies in brain injured patients?
In a recent pilot study, Werndle et al. presented preliminary data of a new technique for the continuous monitoring of spinal cord pressure and the corresponding spinal cord perfusion pressure (Crit Care Med 2014;42:646–655). Their analyses revealed that the use of inotropic drugs for an increase of spinal cord perfusion pressure optimizes neuronal function measured by motoric evoked potentials and muscle strengths below the spinal level of injury.
Are we ready for a routinely monitored management of spinal cord perfusion?
Which mean arterial blood pressure should be targeted in this context?
How long and how invasive should we monitor?
Great questions. I think that this is an important study and that the current formulae to estimate spinal cord perfusion are flawed (basically MAP - CSF pressure). An electrophysiological measure such as an MEP, or actual clinical function is a very meaningful endpoint to guide resuscitation after spinal cord injury. We do require more information about the relationship between estimates of spinal cord pressure and actual tissue oxygenation. In addition these measurments are likely to differ depending upon where the recording device is placed relative to the epicenter of the spinal cord injury. Cranial ICP and perfusion measures went through a lengthy evolution to be validated, and it is likely that this also be true for the spinal cord. Beginning to focus on real time spinal cord physiology after SCI is important. So, I don't think we have sufficient knowledge to routinely monitor, we need to further validate methods. The MAP should probably be tied to a spinal cord physiologic measure. I don't how long monitoring should continue. There are several ways to think about that: infection-risks from recording devices, duration of perfusion-dependent secondary injury mechanisms, recovery of a more normal spinal cord tissue pressure, etc.
This is a great set of questions but I think we need to have the methodologies further validated before they are ready for wide spread use. For example, even if we know the pressure within a region of the spinal cord, it is more important to know the status of tissue oxygenation/hypoxia and how that varies with ranges of spinal cord perfusion pressures. Physiologic measures such as voluntary movement or MEPs are excellent is they are present, in e.g. an incomplete injury.
Q. Are we ready for a routinely monitored management of spinal cord perfusion?
A. We need to have validated correlates to spinal cord perfusion such as the status or tissue oxygenation.
Q.Which mean arterial blood pressure should be targeted in this context?
A. I think the "optimal" MAP should be linked to a physiological endpoint, as compared to a certain recommended number.
Q. How long and how invasive should we monitor?
A. We need further information. How do tissue pressures change over time, how does SCBF change over time? Is there an incremental time-linked risk of infection due to the measurement cannulas, etc.
Thank you Dr. Guest for your valuable comments. I completely agree with your considerations. Although this study provides detailed and well explained information regarding the underlying pathophysiologic mechanisms, we definitively need more studies in this direction to carve out guidelines for clinical practice.
Indeed, a fascinating topic. Thank you Dr. Sutter to bring this up. I came across a recent article by the Cambridge/London group that has enormous experience with ICP. Intra-spinal cord pressure seems to be closely matched to epidural pressure at the level of the lesion in spine-injured patients, which would make pressure monitoring less invasive and still reliable. Regarding spinal perfusion pressure, the evidence being gathered is most convincing for a principle analogous to CCP.
Article Intraspinal pressure and spinal cord perfusion pressure afte...
Thank you Dr. Goettel for this very interesting article. These are indeed very promising results especially if further and larger studies will confirm these preliminary findings. Currently, I could not find any larger studies that validate this method.
- Badges
- Science topic
- Similar topics
- Solid State Physics
- Devices