Feasibility of near infrared spectroscopy in stroke patients

Abstract

Introduction Stroke is the main cause of death in Portugal. It is a severe pathology with a sudden onset and with a very high demand in both time and money from the families of the affected patients and from health organizations and social services. Inexpensive and practical diagnostic tools that will assist in early detection and treatment are the source of numerous studies. The physiology behind a stroke is a sudden ischemic event in the brain. Near infrared spectroscopy (NIRS) is a non-invasive mean of measuring cerebral perfusion in real time. Due to its rapid and recent development few data exists about its applicability. Since NIRS detects oxygen levels that are supposedly low due to oligemia in infarcted areas, our study tried to ascertain the significance of NIRS measurements in stroke patients. Objectives -Determine which systemic factors influence rSO2 values. -Determine NIRS viability in diagnosing and monitoring stroke patients by comparing their values with those of healthy individuals using the reference value of 60 rSO2. -Determine if NIRS is capable of influencing therapeutical changes in those monitored. Methodology This is a prospective study where we used NIRS EQUANOX® technology with 4 sensors: 2 Frontal 2 supra-auricular to compare cerebral oxygen values of rSO2 in a control sample of 60 healthy persons from two retirement homes from the geographical area of Covilhã, Portugal and compared them with 128 stroke patients hospitalized in the Centro Hospitalar Cova da Beira (CHCB). We also collected data consisting of: risk factors, imagiological studies and vital signs. The hospitalized patients were monitored twice on the first day and then once daily during the following four consecutive days for a total of five days. The results were analyzed using SPSS ® software - version 17 for Windows ® and were considered significant at p < 0.05. We resorted to the tests of independence Chi-square and Mann Whitney U to analyze the relationships between variables. Results Our study revealed that the hospitalized stroke patients had higher rSO2 values than healthy individuals from retirement homes, and that these higher values decreased along the week they were hospitalized. We also found that the lesion side diagnosed by CT scan had higher rSO2 values than the contralateral healthy side. We did not find any association between: stroke risk factors and rSO2 readings, use of thrombolysis and rSO2 measurements, the imagiological exams and rSO2 readings (CT, TU and CU) and no association between age or gender with rSO2 levels.