Relationship between dialysis quality and brain compliance in patients with end-stage renal disease (ESRD): a cross-sectional study

ABSTRACT BACKGROUND: The high number of patients with end-stage kidney disease (ESRD) on hemodialysis makes it necessary to conduct studies aimed at improving their quality of life. OBJECTIVES: To evaluate brain compliance, using the Brain4care method for intracranial pressure (ICP) monitoring, among patients with ESRD before and at the end of the hemodialysis session, and to correlate ICP with the dialysis quality index (Kt/V). DESIGN AND SETTING: Cross-sectional study conducted at a renal replacement therapy center in Brazil. METHODS: Sixty volunteers who were undergoing hemodialysis three times a week were included in this study. Brain compliance was assessed before and after hemodialysis using the noninvasive Brain4care method and intracranial pressure wave morphology was analyzed. RESULTS: Among these 60 ESRD volunteers, 17 (28%) presented altered brain compliance before hemodialysis. After hemodialysis, 12 (20%) exhibited normalization of brain compliance. Moreover, 10 (83%) of the 12 patients whose post-dialysis brain compliance became normalized were seen to present good-quality dialysis, as confirmed by Kt/V > 1.2. CONCLUSIONS: It can be suggested that changes to cerebral compliance in individuals with ESRD occur frequently and that a good-quality hemodialysis session (Kt/V > 1.2) may be effective for normalizing the patient's cerebral compliance.

Relationship between dialysis quality and brain compliance in patients with end-stage renal disease (ESRD): a cross-sectional study.

BACKGROUND: The high number of patients with end-stage kidney disease (ESRD) on hemodialysis makes it necessary to conduct studies aimed at improving their quality of life. OBJECTIVES: To evaluate brain compliance, using the Brain4care method for intracranial pressure (ICP) monitoring, among patients with ESRD before and at the end of the hemodialysis session, and to correlate ICP with the dialysis quality index (Kt/V). DESIGN AND SETTING: Cross-sectional study conducted at a renal replacement therapy center in Brazil. METHODS: Sixty volunteers who were undergoing hemodialysis three times a week were included in this study. Brain compliance was assessed before and after hemodialysis using the noninvasive Brain4care method and intracranial pressure wave morphology was analyzed. RESULTS: Among these 60 ESRD volunteers, 17 (28%) presented altered brain compliance before hemodialysis. After hemodialysis, 12 (20%) exhibited normalization of brain compliance. Moreover, 10 (83%) of the 12 patients whose post-dialysis brain compliance became normalized were seen to present good-quality dialysis, as confirmed by Kt/V > 1.2. CONCLUSIONS: It can be suggested that changes to cerebral compliance in individuals with ESRD occur frequently and that a good-quality hemodialysis session (Kt/V > 1.2) may be effective for normalizing the patient's cerebral compliance.

Noninvasive intracranial pressure monitoring in women with migraine.

This cross-sectional study aimed to compare the waveform morphology through noninvasive intracranial pressure (ICP-NI) measurement between patients with migraine and controls, and to analyze the association with clinical variables. Twenty-nine women with migraine, age 32.4 (11.2) years and headache frequency of 12.6 (7.5) days per month and twenty-nine women without headache, age 32.1 (9.0) years, were evaluated. Pain intensity, migraine disability, allodynia, pain catastrophizing, central sensitization and depression were evaluated. The ICP-NI monitoring was performed by a valid method consisting of an extracranial deformation sensor positioned in the patients' scalp, which allowed registration of intracranial pressure waveforms. Heart rate and blood pressure measurements were simultaneously recorded during 20 min in the supine position. The analyzed parameter was the P2/P1 ratio based on mean pulse per minute which P1 represents the percussion wave related to the arterial blood pression maximum and P2 the tidal wave, middle point between the P1 maximum and the dicrotic notch. There was no between-groups difference in the P2/P1 ratio (mean difference: 0.04, IC95%: -0.07 to 0.16, p = 0.352, F (1,1) = 0.881) adjusted by body mass index covariable. The Multiple Linear Regression showed non-statistical significance [F (5,44) = 1.104; p = 0.372; R2 = 0.11)] between the P2/P1 ratio and body mass index, presence of migraine, central sensitization, pain catastrophizing and depression. We found no correlation (p > 0.05) between P2/P1 ratio and migraine frequency, migraine onset, pain intensity, pain intensity at day of examination, disability, allodynia. Migraine patients did not present alterations in the waveform morphology through ICP-NI compared to women without headache and no association with clinical variables was found.

Impairment on Cardiovascular Autonomic Modulation in Women with Migraine.

Autonomic dysfunction, such as reduced vagally mediated heart rate variability, has been suggested in headache patients but is still uncertain when considering primary headache disorders. This study aims to compare the heart rate and blood pressure variability and baroreflex sensitivity between women with migraine and controls. A migraine (n = 20) and a control group (n = 20) of age-matched women without headache were evaluated. Heart rate variability was analyzed through frequency-domain using spectral analysis presenting variance, low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.15-0.4 Hz) bands and by time domain (root mean square of successive R-R interval differences, RMSSD). Blood pressure variability was analyzed with spectral analysis and baroreflex sensitivity with the sequence method. Migraine group had lower heart rate variability characterized by a reduction in total variance, LF oscillations (sympathetic/vagal modulation) and HF oscillations (vagal modulation), and a reduction in SD and RMSSD compared to control group. No difference was found in the blood pressure variability analysis. Regarding baroreflex sensitivity, migraine group had decreased values of total gain, gain down and up compared to control group. Women with migraine exhibited autonomic modulation alterations, expressed by decreased values of heart rate variability and baroreflex sensitivity, but not by differences in blood pressure variability.

Use of non-invasive intracranial pressure pulse waveform to monitor patients with End-Stage Renal Disease (ESRD).

End-stage renal disease (ESRD) is treated mainly by hemodialysis, however, hemodialysis is associated with frequent complications, some of them involve the increased intracranial pressure. In this context, monitoring the intracranial pressure of these patients may lead to a better understanding of how intracranial pressure morphology varies with hemodialysis. This study aimed to follow-up patients with ESRD by monitoring intracranial pressure before and after hemodialysis sessions using a noninvasive method. We followed-up 42 patients with ESRD in hemodialysis, for six months. Noninvasive intracranial pressure monitoring data were obtained through analysis of intracranial pressure waveform morphology, this information was uploaded to Brain4care® cloud algorithm for analysis. The cloud automatically sends a report containing intracranial pressure parameters. In total, 4881 data points were collected during the six months of follow-up. The intracranial pressure parameters (time to peak and P2/P1 ratio) were significantly higher in predialysis when compared to postdialysis for the three weekly sessions and throughout the follow-up period (p<0.01) data showed general improvement in brain compliance after the hemodialysis session. Furthermore, intracranial pressure parameters were significantly higher in the first weekly hemodialysis session (p<0.05). In conclusion, there were significant differences between pre and postdialysis intracranial pressure in patients with ESRD on hemodialysis. Additionally, the pattern of the intracranial pressure alterations was consistent over time suggesting that hemodialysis can improve time to peak and P2/P1 ratio which may reflect in brain compliance.

New device for active gastric mechanical stimulation.

BACKGROUND: Gastroparesis is a chronic stomach disorder and effective treatment is the aim of different strategies. Alternative therapies consist of an electrical stimulation of the stomach to evoke a response in the gastric activity. We present the development and in vivo application of an electromagnet system to induce a mechanical stimulus in the stomach aiming for gastric contractile responses. METHODS: The electromagnet system consisted of an implantable magnet and an external drive coil. We implanted the magnet at the greater curvature of the gastric body in rats. We applied an alternating current to the drive coils, inducing mechanical stimulation of the gastric wall. We measured the gastric contraction activity and gastric electrical activity in response to the stimulus using AC biosusceptometry and electrogastrography. Moreover, we used the phenol red to evaluate the stimulus effects on gastrointestinal transit. KEY RESULTS: The stimulus increased the spectral intensity and signal-to-noise ratio significantly of gastric contraction activity and gastric electrical activity. Furthermore, we found a lower phenol red retention in the stomach in rats without stimulus. No significant differences were found in frequency and root mean square amplitude. CONCLUSIONS & INFERENCES: We developed a new simple electromagnet system that evoked a contraction and gastric electrical response using a mechanical stimulus and decreased gastric emptying time. The system is an accessible tool and may contribute to gastroparesis studies in animals.

Comparison of Waveforms Between Noninvasive and Invasive Monitoring of Intracranial Pressure.

Intracranial pressure (ICP) is an important invasive monitoring parameter in management of patients with acute brain injury and compromised compliance. This study aimed to compare waveforms obtained from standard ICP monitoring and noninvasive ICP monitoring (nICP) methods.We analyzed continuous arterial blood pressure (ABP) waves, ICP (with standard monitoring), and nICP recorded simultaneously. All signal recordings were sliced into data chunks, each 1 min in duration, and from the mean pulse, we determined the time to peak (Tp) and the ratio between tidal and percussion waves (P2/P1). We also calculated the Isomap projection of the pulses into a bidimensional space-K1 and K2. The defined nICP and ICP parameters were compared using a unilateral Wilcoxon-Mann-Whitney test. The Pearson correlation coefficient and normalized mutual information were used to verify the association between parameters.In total, 1504 min of monitoring from ten patients were studied. Nine of the patients were male. The mean age of the patients was 58.4 ± 10.4 years, and they had an initial Glasgow Coma Scale of 9 ± 4, a mean Simplified Acute Physiology Score (SAPS II) of 45.6, and an intensive care unit stay of 44 ± 45 days. With the exception of Tp, all parameters showed a weak linear association but presented a strong nonlinear association.Mutual information analysis and a bigger sample size would be helpful to build more refined models and to improve understanding of the waveform relationships.

Tracking pregnant women displacements in Sao Paulo, Brazil: a complex systems approach to regionalization through the emergence of patterns.

BACKGROUND: The healthcare system can be understood as the dynamic result of the interaction of hospitals, patients, providers, and government configuring a complex network of reciprocal influences. In order to better understand such a complex system, the analysis must include characteristics that are feasible to be studied in order to redesign its functioning. The analysis of the emergent patterns of pregnant women flows crossing municipal borders for birth-related hospitalizations in a region of São Paulo, Brazil, allowed to examine the functionality of the regional division in the state using a complex systems approach and to propose answers to the dilemma of concentration vs. distribution of maternal care regional services in the context of the Brazilian Unified Health System (SUS). METHODS: Cross-sectional research of the areas of influence of hospitals using spatial interaction methods, recording the points of origin and destination of the patients and exploring the emergent patterns of displacement. RESULTS: The resulting functional region is broader than the limits established in the legal provisions, verifying that 85% of patients move to hospitals with high technology to perform normal deliveries and cesarean sections. The region has high independence rates and behaves as a "service exporter." Patients going to centrally located hospitals travel twice as long as patients who receive care in other municipalities even when the patients' conditions do not demand technologically sophisticated services. The effects of regulation and the agents' preferences reinforce the tendency to refer patients to centrally located hospitals. CONCLUSIONS: Displacement of patients during delivery may affect indicators of maternal and perinatal health. The emergent pattern of movements allowed examining the contradiction between wider deployments of services versus concentration of highly specialized resources in a few places. The study shows the potential of this type of analysis applied to other type of patients' flows, such as cancer or specialized surgery, as tools to guide the regionalization of the Brazilian Health System.

Electron spin resonance (ESR) dose measurement in bone of Hiroshima A-bomb victim.

Explosion of the bombs in Hiroshima and Nagasaki corresponds to the only historical moment when atomic bombs were used against civilians. This event triggered countless investigations into the effects and dosimetry of ionizing radiation. However, none of the investigations has used the victims' bones as dosimeter. Here, we assess samples of bones obtained from fatal victims of the explosion by Electron Spin Resonance (ESR). In 1973, one of the authors of the present study (SM) traveled to Japan and conducted a preliminary experiment on the victims' bone samples. The idea was to use the paramagnetism induced in bone after irradiation to measure the radiation dose. Technological advances involved in the construction of spectrometers, better knowledge of the paramagnetic center, and improvement in signal processing techniques have allowed us to resume the investigation. We obtained a reconstructed dose of 9.46 ± 3.4 Gy from the jawbone, which was compatible with the dose distribution in different locations as measured in non-biological materials such as wall bricks and roof tiles.

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.

Characterization of ICP Behavior in an Experimental Model of Hemorrhagic Stroke in Rats.

Intracranial pressure (ICP) monitoring is sometimes required in clinical pictures of stroke, as extensive intraparenchymal hematomas and intracranial bleeding may severely increase ICP, which can lead to irreversible conditions, such as dementia and cognitive derangement. ICP monitoring has been accepted as a procedure for the safe diagnosis of increased ICP, and for the treatment of intracranial hypertension in some diseases. In this work, we evaluated ICP behavior during the induction of an experimental model of autologous blood injection in rats, simulating a hemorrhagic stroke. Rats were subjected to stereotactic surgery for the implantation of a unilateral cannula into the left striatal region of the brain. Autologous blood was infused into the left striatal region with an automatic microinfusion pump. ICP monitoring was performed throughout the procedure of hemorrhagic stroke induction. Analyses consisted of short-time Fourier transform for ICP before and after stroke induction and the histological processing of the animals' brains. Short-time Fourier transform analysis demonstrated oscillations in the ICP frequency components throughout time after the microinjections compared with data before them. Histological analysis revealed neuropathological changes in the striatum in all microinjected animals.

Characterization of Intracranial Pressure Behavior in Chronic Epileptic Animals: A Preliminary Study.

Intracranial pressure (ICP) is a major neurological parameter in animals and humans. ICP is a function of the relationship between the contents of the cranium (brain parenchyma, cerebrospinal fluid, and blood) and the volume of the skull. Increased ICP can cause serious physiological effects or even death in patients who do not quickly receive proper care, which includes ICP monitoring. Epilepsies are a set of central nervous system disorders resulting from abnormal and excessive neuronal discharges, usually associated with hypersynchronism and/or hyperexcitability. Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy and is also refractory to medication. ICP characteristics of subjects with epilepsy have not been elucidated because there are few studies associating these two important neurological factors. In this work, an invasive (ICPi) and the new minimally invasive (ICPmi) methods were used to evaluate ICP features in rats with chronic epilepsy, induced by the experimental model of pilocarpine, capable of generating the main features of human TLE in these animals.

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods.

Elevation of intracranial pressure (ICP) may occur in many diseases, and therefore the ability to measure it noninvasively would be useful. Flow velocity signals from transcranial Doppler (TCD) have been used to estimate ICP; however, the relative accuracy of these methods is unclear. This study aimed to compare four previously described TCD-based methods with directly measured ICP in a prospective cohort of traumatic brain-injured patients. Noninvasive ICP (nICP) was obtained using the following methods: 1) a mathematical "black-box" model based on interaction between TCD and arterial blood pressure (nICP_BB); 2) based on diastolic flow velocity (nICP_FVd); 3) based on critical closing pressure (nICP_CrCP); and 4) based on TCD-derived pulsatility index (nICP_PI). In time domain, for recordings including spontaneous changes in ICP greater than 7 mm Hg, nICP_PI showed the best correlation with measured ICP (R = 0.61). Considering every TCD recording as an independent event, nICP_BB generally showed to be the best estimator of measured ICP (R = 0.39; p < 0.05; 95% confidence interval [CI] = 9.94 mm Hg; area under the curve [AUC] = 0.66; p < 0.05). For nICP_FVd, although it presented similar correlation coefficient to nICP_BB and marginally better AUC (0.70; p < 0.05), it demonstrated a greater 95% CI for prediction of ICP (14.62 mm Hg). nICP_CrCP presented a moderate correlation coefficient (R = 0.35; p < 0.05) and similar 95% CI to nICP_BB (9.19 mm Hg), but failed to distinguish between normal and raised ICP (AUC = 0.64; p > 0.05). nICP_PI was not related to measured ICP using any of the above statistical indicators. We also introduced a new estimator (nICP_Av) based on the average of three methods (nICP_BB, nICP_FVd, and nICP_CrCP), which overall presented improved statistical indicators (R = 0.47; p < 0.05; 95% CI = 9.17 mm Hg; AUC = 0.73; p < 0.05). nICP_PI appeared to reflect changes in ICP in time most accurately. nICP_BB was the best estimator for ICP "as a number." nICP_Av demonstrated to improve the accuracy of measured ICP estimation.

The new ICP minimally invasive method shows that the Monro-Kellie doctrine is not valid.

The Monro-Kellie doctrine states that the interior of the cranium is formed of three main components: blood, fluid and cerebral parenchyma. An increase in the volume of one or more components may increase the intracranial pressure (ICP). This doctrine also affirms that the skull cannot be expanded after the closure of the fontanels. Monro and Kellie's theory has been perfected during the last two centuries. This study leads to a new contribution that proves that even adults' consolidated skulls present volumetric changes as a consequence of ICP variations.