There is a need for continuous, non-invasive neurologic monitoring in patients who are suffering from a significant neurologic insult such as stroke, intracerebral hemorrhage (ICH) or traumatic brain injury. Currently, these patients are typically sedated and/or intubated in the ICU setting, making it difficult for the clinician to assess their neurologic status. A device capable of non-invasively determining acute changes in brain function would be of great utility in this clinical setting. Here, we present the results of a pilot study of a non-invasive radiofrequency (RF) electromagnetic (EM) radiation device to detect acute blood in a well-established in vivo porcine ICH model.
Methods:
Two antennae were placed collinearly with the upper eyelids of a sedated, anesthetized pig, after local IACUC approval of the protocol. An RF signal was transmitted by one antenna across the head of the pig and received by the other antenna, which was connected to a spectrum analyzer to measure received power (Pr). Blood (3 mL) was infused into the frontal lobe white matter at the level of the upper eyelids. Pr values were collected for the healthy pig (Pr(control)), after infusion of ICH (Pr(ICH)), and 30 minutes after Pr(ICH) measurement (Pr(clot)). Clot size was determined by measuring the clot in post-mortem frozen brain slices. Seven pig experiments were conducted. A student’s paired t-test was used for statistical analysis, and P < 0.05 was considered to be significant.
Results:
A 12% (SD: 6%) increase in Pr(ICH) was seen compared to Pr(control) (P = 0.003). Pr(clot) also increased by 13% (SD: 10%) compared to Pr(control) but the difference was not significant (P = 0.053). The average clot size was 1.2mL.
Conclusion:
It has been demonstrated that an RF EM signal can be used to detect acute ICH in an in vivo porcine model. A non-invasive sensor based on this technique may be useful in monitoring the neurologically injured patient.
In vivo study of non-invasive effects of non-thermal plasma in pressure ulcer treatment
