Intracranial compliance in type 2 diabetes mellitus and its relationship with the cardiovascular autonomic nervous control.

The intracranial compliance in type 2 diabetes mellitus (T2DM) patients and the association with cardiovascular autonomic control have not been fully elucidated. The aim of this study was to assess intracranial compliance using the noninvasive intracranial pressure (niICP) and the monitoring of waveform peaks (P1, P2, and P3) and the relationship with cardiovascular autonomic control in T2DM patients. Thirty-two men aged 40-60 years without cardiovascular autonomic neuropathy (CAN) were studied: T2DMG (n=16) and control group CG (n=16). The niICP was evaluated by a noninvasive extracranial sensor placed on the scalp. Cardiovascular autonomic control was evaluated by indices of the baroreflex sensitivity (BRS), from temporal series of R-R intervals of electrocardiogram and systolic arterial pressure, during supine and orthostatic positions. The participants remained in the supine position for 15 min and then 15 min more in orthostatism. T2DMG presented a decrease of the P2/P1 ratio during the orthostatic position (P<0.001). There was a negative moderate correlation between the P2 peak with cardiovascular coupling (K2HP-SAPLF) in supine (r=-0.612, P=0.011) and orthostatic (r=-0.568, P=0.020) positions in T2DMG. We concluded that T2DM patients without CAN and cardiovascular complications presented intracranial compliance similar to healthy subjects. Despite preserved intracranial adjustments, T2DM patients had a response of greater magnitude in orthostatism. In addition, the decoupling between the heart period and blood pressure signal oscillations in low frequency appeared to be related to the worsening of intracranial compliance due to the increased P2 peak.

Analysis of a Minimally Invasive Intracranial Pressure Signals During Infusion at the Subarachnoid Spinal Space of Pigs.

OBJECTIVE: We developed a new minimally invasive method for intracranial pressure monitoring (ICPMI). The objective of this project is to verify the similarities between the ICPMI and the invasive method (ICPInv), for different components of the intracranial pressure signal-namely, the mean value (trend) as well as its pulsatile component. MATERIALS AND METHODS: A 9 kg anesthetized pig was used for simultaneous ICP monitoring with both methods. ICP was increased by performing ten infusions of 6 ml 0.9% saline into the spinal subarachnoid space, using a catheter implanted in the lumbar region. For correlation analysis, the signals were decomposed into two components-trend and pulsatile signals. Pearson correlation coefficient was calculated between ICPInv and ICPMI. RESULTS: During the infusions, the correlation between the pulsatile components of the signals was above 0.5 for most of the time. The signal trends showed a good agreement (correlation above 0.5) for most of the time during infusions. CONCLUSIONS: The ICPMI signal trends showed a good linear agreement with the signal obtained invasively. Based on the waveform analysis of the pulsatile component of ICP, our results indicate the possibility of using the minimally invasive method for assessing the neuroclinical state of the patient.

Analysis of a Non-invasive Intracranial Pressure Monitoring Method in Patients with Traumatic Brain Injury.

OBJECTIVE: We aimed to compare the invasive (iICP) and a non-invasive intracranial pressure (nICP) monitoring methods in patients with traumatic brain injury, based on the similarities of the signals' power spectral densities. MATERIALS AND METHODS: We recorded the intracranial pressure of seven patients with traumatic brain injury admitted to Hospital São João, Portugal, using two different methods: a standard intraparenchymal (iICP) and a new nICP method based on mechanical extensometers. The similarity between the two monitoring signals was inferred from the Euclidean distance between the non-linear projection in a lower dimensional space (ISOMAP) of the windowed power spectral densities of the respective signals. About 337 h of acquisitions were used out of a total of 608 h. The only data exclusion criterion was the absence of any of the signals of interest. RESULTS: The averaged distance between iICP and nICP, and between arterial blood pressure (ABP) and nICP projections in the embedded space are statistically different for all seven patients analysed (Mann-Whitney U, p < 0.05). CONCLUSIONS: The similarity between the iICP and nICP monitoring methods was higher than the similarity between the nICP and the recordings of the radial ABP for all seven patients. Despite the possible differences between the shape of the ABP waveform at radial and parietal arteries, the results indicate-based on the similarities of iICP and nICP as functions of time-that the nICP method can be applied as an alternative method for ICP monitoring.

Noninvasive intracranial pressure monitoring for HIV-associated cryptococcal meningitis.

Mortality and adverse neurologic sequelae from HIV-associated cryptococcal meningitis (HIV-CM) remains high due to raised intracranial pressure (ICP) complications. Cerebrospinal fluid (CSF) high opening pressure occurs in more than 50% of HIV-CM patients. Repeated lumbar puncture with CSF drainage and external lumbar drainage might be required in the management of these patients. Usually, there is a high grade of uncertainty and the basis for clinical decisions regarding ICP hypertension tends to be from clinical findings (headache, nausea and vomiting), a low Glasgow coma scale score, and/or fundoscopic papilledema. Significant neurological decline can occur if elevated CSF pressures are inadequately managed. Various treatment strategies to address intracranial hypertension in this setting have been described, including: medical management, serial lumbar punctures, external lumbar and ventricular drain placement, and either ventricular or lumbar shunting. This study aims to evaluate the role of a non-invasive intracranial pressure (ICP-NI) monitoring in a critically ill HIV-CM patient.