Avaliação do modelo da curva de onda de pulso da pressão intracraniana avaliada por um método não invasivo

Abstract

Introduction: Intracranial pressure (ICP) is determined by the dynamics of volumes such as brain, blood and cerebrospinal fluid, interacting with structures such as the meninges and braincase. Increased ICP can occur in a series of neurological conditions such as traumatic brain injury and stroke, and determines a reduction in cerebral perfusion pressure with consequent cellular damage. Recently, a non-invasive system capable of capturing the morphology of intracranial pressure waves was developed, seeking quantitative parameters that may suggest a reduction in cerebral compliance and intracranial hypertension. However, to date, reference values for these parameters have not been predicted in individuals without neurological complaints. Objective: To determine the reference values obtained from the analysis of ICP pulse wave morphology using a non-invasive system in neurologically healthy participants in the horizontal supine position at 0 and 45 degrees. Method: This is an analytical and cross sectional study. Inclusion criteria were participants aged between 8 and over 65 years; neurologically healthy; and without a history of neurological diseases. The non-invasive Brain4care analysis system was used to analyze the P2/P1 ratio, time to peak of the wave, and pulse amplitude. Results: A total of 120 participants were evaluated, of which 65 (54.17%) were female. The average age was 39.47 years (SD ± 17.75), ranging from 8 to 83 years. The medians of the evaluated parameters were: for the P2/P1 ratio, 1.085 (P25 = 0.81; P75 = 1.25) at 0° and 1.065 (P25 = 0.92; P75 = 1.30) at 45°; for time to peak, 0.22 seconds (P25 = 0.11; P75 = 0.28) at 0° and 0.21 seconds (P25 = 0.11; P75 = 0.27) at 45°; and for pulse amplitude, 6.8 µV (P25 = 4.45; P75 = 9.80) at 0° and 6.0 µV (P25 = 4.30; P75 = 9.25) at 45°. There was a moderate correlation between age and the P2/P1 ratio at 0 and 45 degrees (r=0.43, p<0.0001, for both). In the multivariate analysis, the main variables associated with the P2/P1 ratio were age and gender (p<0.001 and p=0.014, respectively). Conclusion: This study established reference values for a non-invasive method of assessing intracranial compliance across different age groups. Furthermore, it was found that the values of the P2/P1 ratio may be primarily affected by the variables of age and gender.