Patient State Index Detects Changes in Cerebral Blood Flow and May Predict New Ischemic Lesions during Carotid Stenting—Case Report

Ana B.  Fernández

doi:10.4236/ojanes.2015.51004

Ana B. Fernández

Abstract: Carotid angioplasty and stenting (CAS) was developed to be a less invasive and complex procedure compared to carotid endarterectomy (CEA). It has emerged as an alternative for patients who are considered to have high surgical risks due to medical comorbidities or anatomical high-risk features [1]. The procedure is usually done under local anesthesia with light sedation, with the subsequent expectation of less neurologic injury, venous thromboembolisms, and myocardial infarctions—all well-known clinical risks of undergoing surgical procedures under general anesthesia. CAS, however, carries some increased risks of arterial dissection, dislocation of atherothrombotic debris and embolization to the brain or eye, late embolization due to thrombus formation on the damaged plaque, and bradycardia and hypotension as a result of carotid sinus stimulation. Electroencephalography can detect cerebral ischemia and hypoxia along with measuring hypnotic effects, but has not been reported to be used during CAS to signal impending neurological deficit and allow for intervention to prevent stroke. We report on the use of patient state index (PSI), an electroencephalographic (EEG) derived variable used by SEDLine monitor (Masimo Inc., San Diego, CA) to monitor changes in cerebral blood flow during carotid angioplasty and stenting in an awake patient under local anesthesia. PSI was developed to measure the level of hypnosis and sedation during anesthesia and in the ICU. The PSI is based on quantitative electroencephalogram features, recorded from anterior and posterior scalp sites, as input to a multivariate algorithm that quantifies the most probable level of anesthesia or sedation. The PSI is reported as a range from 0 to 100, with decreasing values indicating increasing levels of anesthesia or sedation. Adequate depth of anesthesia is reflected by PSI value of 25 - 50, and a fully awake state by a PSI of 100 [2]. Other EEG analysis techniques have been explored to detect changes in cerebral blood flow during carotid surgery [3], such as entropy described by Khan and Ozcan in his recent work entitled Disagreement in Bilateral State Entropy Values in Carotid Artery Disease [4], but there are no previous reports of the use of PSI during procedural sedation in carotid angioplasty and stenting in an awake patient.

Keywords: Patient State Index (PSI), Carotid Angioplasty, Cerebral Ischemia, EEG Analysis

Cite this paper: Fernández, A. (2015) Patient State Index Detects Changes in Cerebral Blood Flow and May Predict New Ischemic Lesions during Carotid Stenting—Case Report. Open Journal of Anesthesiology, 5, 20-22. doi: 10.4236/ojanes.2015.51004.

References

[1] Erikson, K.M. and Cole, D.J. (2010) Carotid Artery Disease: Stenting vs Endarterectomy. British Journal of Anesthesia, 105, i34-i49.
http://dx.doi.org/10.1093/bja/aeq319

[2] Caputo, T., Ramsay, M., Rossmann, J., Beach, M., Griffiths, G., Meyrat, B., et al. (2011) Evaluation of the SED Line to Improve the Safety and Efficiency of Conscious Sedation. Baylor University Medical Center Proceedings, 24, 200-204.

[3] Skordilis, M., Rich, N., Viloria, A., Dimitrova, G., Bergese, S. and Dzwonczyk, R. (2011) Processed Electroencephalogram Response of Patients Undergoing Carotid Endarterectomy: A Pilot Study. Annals of Vascular Surgery, 25, 909-912.
http://dx.doi.org/10.1016/j.avsg.2011.05.011

[4] Khan, Q.S. and Ozcan, M.S. (2011) Disagreement in Bilateral State Entropy Values in Carotid Artery Disease. Journal of Neurosurgical Anesthesiology, 23, 51-52.
http://dx.doi.org/10.1097/ANA.0b013e3181f0461f

[5] Chaer, R. and Schneider, P. (2010) Carotid Stenting. Peripheral Endovascular Interventions, Part 5, 349-368.
http://dx.doi.org/10.1007/978-1-4419-1387-6_24

[6] Altinbas, A., et al. (2011) Cognition after Carotid Endarterectomy or Stenting: A Randomized Comparison. Neurology, 77, 1084-1090.
http://dx.doi.org/10.1212/WNL.0b013e31822e55b9

[7] Wasser, K., et al. (2011) New Brain Lesions after Carotid Revascularization Are Not Associated with Cognitive Performance. Journal of Vascular Surgery, 53, 61-70.
http://dx.doi.org/10.1016/j.jvs.2010.07.061

[8] Wasser, K., et al. (2012) Age-Dependent Effects of Carotid Endarterectomy or Stenting on Cognitive Performance. Journal of Neurology, 259, 2309-2318.
http://dx.doi.org/10.1007/s00415-012-6491-9