Intracranial compliance in patients with COVID-19: a multicenter observational study.

BACKGROUND: Patients with severe coronavirus disease-19 (COVID-19) may require the use of invasive mechanical ventilation (MV) for prolonged periods. Aggressive MV parameters have been associated with changes in intracranial pressure (ICP) in patients with acute intracranial disorders. Significant ICP elevation could compromise intracranial compliance (ICC) and cerebrovascular hemodynamics (CVH). However, the effects of these parameters in individuals without neurological disorders have not yet been evaluated. OBJECTIVE: To evaluate ICC in patients on MV with COVID-19 infection compared to other diagnoses, to better characterize the effects of MV and COVID-19 upon ICC. We also compared between the ICC in patients with COVID-19 who did not require MV and healthy volunteers, to assess the isolated effect of COVID-19 upon ICC. METHODS: This was an exploratory, observational study with a convenience sample. The ICC was evaluated with a noninvasive ICP monitoring device. The P2/P1 ratio was calculated by dividing the amplitude of these two points, being defined as "abnormal" when P2 > P1. The statistical analysis was performed using a mixed linear model with random effects to compare the P2/P1 ratio in all four groups on the first monitoring day. RESULTS: A convenience sample of 78 subjects (15 MV-COVID-19, 15 MV non-COVID-19, 24 non-MV-COVID-19, and 24 healthy participants) was prospectively enrolled. There was no difference in P2/P1 ratios between MV patients with and without COVID-19, nor between non-MV patients with COVID-19 and healthy volunteers. However, the P2/P1 ratio was higher in COVID-19 patients with MV use than in those without it. CONCLUSION: This exploratory analysis suggests that COVID-19 does not impair ICC.

ANTECEDENTES: Pacientes com doença grave por coronavírus-19 (COVID-19) podem necessitar do uso de ventilação mecânica (VM) invasiva por um período prolongado. Parâmetros agressivos de VM têm sido associados a alterações na pressão intracraniana (PIC) em pacientes com doenças intracranianas agudas. Elevações significativas da PIC podem comprometer a complacência intracraniana (CIC) e a hemodinâmica cerebrovascular (HVC). No entanto, os efeitos desses parâmetros em indivíduos sem doenças neurológicas ainda não foram sistematicamente avaliados. OBJETIVO: Avaliar a CIC em pacientes em VM com COVID-19 comparados com outros diagnósticos, para melhor caracterizar os efeitos da VM e COVID-19 sobre a CIC. Também foi feita a comparação entre a CIC em pacientes com COVID-19 sem VM e voluntários saudáveis, para avaliar o efeito isolado da COVID-19 sobre a ICC. MéTODOS: Trata-se de um estudo exploratório, observacional com amostra por conveniência. A CIC foi avaliada com um dispositivo não invasivo de monitoramento da PIC. A relação P2/P1 foi calculada dividindo-se a amplitude desses dois pontos, sendo definida como "anormal" quando P2 > P1. A análise estatística foi realizada usando um modelo linear misto com efeitos aleatórios para comparar a relação P2/P1 nos quatro grupos no primeiro dia de monitoramento. RESULTADOS: Uma amostra de conveniência com 78 voluntários (15 COVID-19 em VM, 15 sem COVID-19 em VM, 24 com COVID em respiração espontânea e 24 saudáveis) foram prospectivamente incluídos. Não houve diferença nas razões P2/P1 entre pacientes em VM com e sem COVID-19, nem entre pacientes sem VM com COVID-19 ou saudáveis. No entanto, a relação P2/P1 foi maior em pacientes com COVID-19 com uso de VM do que naqueles sem. CONCLUSãO: Os dados dessa análise exploratória sugerem que a COVID-19 não prejudica a CIC.

Comparison of Noninvasive Measurements of Intracranial with Tap Test Results in Patients with Idiopathic Normal Pressure Hydrocephalus.

Background: Normal pressure hydrocephalus is a disease directly related to the change in intracranial compliance and consequent repercussions in the brain parenchyma. Invasive monitoring of such parameters proves to be reliable especially for prognosis in neurocritical patients; however, it is not applicable in an outpatient service setting. The present study describes the comparison between the tap test results and the parameters obtained with a non-invasive sensor for monitoring intracranial compliance in patients with suspected NPH. Methods: Twenty-eight patients were evaluated before and after lumbar puncture of 50mL of CSF (the tap test), comprising clinical assessment, magnetic resonance imaging, physical therapy assessment using the Timed Up and Go test, Dynamic Gait Index, BERG test, neuropsychological assessment, and recording of non-invasive intracranial compliance data using the Brain4care® device in three different positions (lying, sitting, and standing) for 5 min each. The tap test results were compared to the Time to Peak and P2/P1 ratio parameters obtained by the device. Results: The group that had a positive Tap test result presented a median P2/P1 ratio greater than 1.0, suggesting a change in intracranial compliance. In addition, there was also a significant difference between patients with positive, negative, and inconclusive results, especially in the lying position. Conclusion: A non-invasive intracranial compliance device when used with the patient lying down and standing up obtained parameters that suggest correspondence with the result of the tap test.

Noninvasive intracranial pressure real-time waveform analysis monitor during prostatectomy robotic surgery and Trendelenburg position: case report.

Both robotic surgery and head-down tilt increase intracranial pressure by impairing venous blood outflow. Prostatectomy is commonly performed in elderly patients, who are more likely to develop postoperative cognitive disorders. Therefore, increased intracranial pressure could play an essential role in cognitive decline after surgery. We describe a case of a 69-year-old male who underwent a robotic prostatectomy. Noninvasive Brain4careTM intraoperative monitoring showed normal intracranial compliance during anesthesia induction, but it rapidly decreased after head-down tilt despite normal vital signs, low lung pressure, and adequate anesthesia depth. We conclude that there is a need for intraoperative intracranial compliance monitoring since there are major changes in cerebral compliance during surgery, which could potentially allow early identification and treatment of impaired cerebral complacency.

Serum Myeloperoxidase, C-reactive Protein and α1-acid Glycoprotein: Insights about Cardiovascular Risk in End-stage Renal Disease.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death in patients with end-stage renal disease (ESRD). Elevated serum concentrations of myeloperoxidase (MPO) are associated with an increased risk of developing CVD. The objective of this study was to evaluate serum MPO levels, as well as other laboratory parameters, in individuals with ESRD, with and without CVD, undergoing hemodialysis. METHODS: 80 volunteers were admitted, divided into the following groups: control group (CON): 20 individuals without chronic kidney disease (CKD); ESRD group: 45 individuals with CKD stage V and ESRD/CVD group: 15 individuals with CKD stage V and with CVD. The following biomarkers were evaluated: MPO, High sensitivity C-reactive protein (hs-CRP) and α1-acid glycoprotein, following the manufacturer's guidelines in the package inserts. The data were processed through the statistical software SPSS 20.0®. RESULTS: The level of MPO for the CON group was 84 ng/mL (73-87 ng/mL), for the ESRD group 77 ng/mL (11-89 ng/mL) and for the ESRD/CVD group 21 ng/mL (8-47 ng/mL), with a significant statistical difference of the ESRD/CVD group from the CON and ESRD groups (p<0.001). For the parameters hs-CRP and α1-acid glycoprotein a statistical difference between the ESRD and ESRD/CVD groups from the CON group (p<0.0001) was observed, but not between the ESRD and ESRD/CVD groups. CONCLUSION: It is suggested that further studies should be performed to define the potential role of MPO as a cardiovascular risk marker for patients with ESRD on hemodialysis.

Validation of a New Minimally Invasive Intracranial Pressure Monitoring Method by Direct Comparison with an Invasive Technique.

In this chapter we present in vivo experiments with a new minimally invasive method of monitoring intracranial pressure (ICP). Strain gauge deformation sensors are externally glued onto the exposed skull. The signal from these sensors is amplified, filtered, and sent to a computer with appropriate software for analysis and data storage. Saline infusions into the spinal channel of rats were performed to produce ICP changes, and minimally invasive ICP and direct Codman intraparenchymal ICP were simultaneously acquired in six animals. The similarity between the invasive and minimally invasive methods in response to ICP increase was assessed using Pearson's correlation coefficient. It demonstrated good agreement between the two measures < r > = 0.8 ± 0.2, with a range of 0.31-0.99.

Validation of a New Noninvasive Intracranial Pressure Monitoring Method by Direct Comparison with an Invasive Technique.

The search for a completely noninvasive intracranial pressure (ICPni) monitoring technique capable of real-time digitalized monitoring is the Holy Grail of brain research. If available, it may facilitate many fundamental questions within the range of ample applications in neurosurgery, neurosciences and translational medicine, from pharmaceutical clinical trials, exercise physiology, and space applications. In this work we compare invasive measurements with noninvasive measurements obtained using the proposed new noninvasive method. Saline was infused into the spinal channel of seven rats to produce ICP changes and the simultaneous acquisition of both methods was performed. The similarity in the invasive and noninvasive methods of ICP monitoring was calculated using Pearson's correlation coefficients (r). Good agreement between measures < r > = 0.8 ± 0.2 with a range 0.28-0.96 was shown.