Third Space Research Articles

Accelerated lymph flow from infusion of crystalloid fluid during general anesthesia

BackgroundKinetic analysis of crystalloid fluid yields a central distribution volume (Vc) of the same size as the expected plasma volume (approximately 3 L) except during general anesthesia during which Vc might be only half as large. The present study examined whether this difference is due to influence of the intravascular albumin balance.MethodsA population volume kinetic analysis according to a three-compartment model was performed based on retrospective data from 160 infusion experiments during which 1–2.5 L of crystalloid fluid had been infused intravenously over 20–30 min. The plasma dilution based on blood hemoglobin (Hb) and plasma albumin (Alb) was measured on 2,408 occasions and the urine output on 454 occasions. One-third of the infusions were performed on anesthetized patients while two-thirds were given to awake healthy volunteers.ResultsThe Hb-Alb dilution difference was four times greater during general anesthesia than in the awake state (+ 0.024 ± 0.060 versus − 0.008 ± 0.050; mean ± SD; P < 0.001) which shows that more albumin entered the plasma than was lost by capillary leakage. The Hb-Alb dilution difference correlated strongly and positively with the kinetic parameters governing the rate of fluid transfer through the fast-exchange interstitial fluid compartment (k12 and k21) and inversely with the size of Vc. Simulations suggest that approximately 200 mL of fluid might be translocated from the interstitial space to the plasma despite ongoing fluid administration.ConclusionsPronounced plasma volume expansion early during general anesthesia is associated with a positive intravascular albumin balance that is due to accelerated lymphatic flow. This phenomenon probably represents adjustment of the body fluid volumes to anesthesia-induced vasodilatation.

Abstract 3391: Effects of repeated psychological stress on NNK-induced lung cancer development in young female mice

Abstract Lung cancer is the second most common cancer in both men and women in the US and the leading cause of cancer death. Among younger US women, lung cancer incidence rates have in recent years become higher than rates seen in men, despite comparable histories of tobacco use. The possible contribution of stress to higher lung cancer risk in young women has received little research attention despite preclinical evidence that exposure to stress-related neuroendocrine responses can cause DNA damage. The present study used a well-established lung cancer model in young female mice (in vivo exposure to NNK) along with a mouse stress model to explore their independent and combined effects on lung cancer development. In addition, we explored one possible biological pathway by chronic administration of a beta-adrenergic receptor blocker (propranolol). We also tested the use of in vivo imaging for repeated monitoring of tumor development over time. Cohort 1 (n=60) had 4 groups: Home cage control, NNK treatment alone, repeated stress (RS) alone and NNK+RS. Cohort 2 (n=60) had the same 4 groups with the addition of administration of propranolol in drinking water. Cohort 3 (n=48, imaging cohort) had 3 groups: Home cage control, NNK alone and NNK+RS. FVB/N (4-6 wk) were purchased from a commercial supplier and acclimated with gentle handling for two weeks. The repeated stress protocol began week-3 and continued for the duration of the study. It combined two well-established rodent models: social disruption stress via changes in cage mates at the time of cage cleaning (2x/week) and a 90-minute restraint stress immediately prior to cage change (1x/week). NNK or saline treatment began on week-4 (IP; 2x/week; 3 mg/injection) and continued for 4 weeks. 21 weeks after stress initiation, the mice in cohorts 1 and 2 were sacrificed, lungs removed, inflated and tumors counted and sized. Mice in cohort 3 were imaged by Hounsfield-calibrated micro-CT (μCT) at baseline, 14, 19 and 23 weeks. The entire lung space, excluding the heart, was defined as a volumetric region of interests (VOIs). The VOIs were subjected to thresholding to segment the lungs into air space and tissue space compartments. The volume of tissue space of each animal was ratioed against its own baseline tissue space volume. Results from Cohort 1 revealed significantly greater numbers and overall size of lung tumors in stressed mice that received NNK. No significant effects were seen in the absence of NNK. Results from Cohort 2 revealed no significant differences between stressed and unstressed groups treated with propranolol. Cohort 3 revealed a pattern of results with stressed mice generally showing the highest lung tumor volume levels (Hounsfield Units), which reached significance at 19 weeks in preliminary analyses. Conclusion: In this study, we found that repeated stress increased lung tumor burden in female mice treated with NNK, and that a beta-adrenergic pathway may be involved. Citation Format: Frank Jenkins, Laura P. Stabile, Jessie R. Nedrow, Kathryn Day, Joseph D. Latoche, Patrick M. Tarwater, Jessica Manculich, Dana H. Bovbjerg. Effects of repeated psychological stress on NNK-induced lung cancer development in young female mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3391.

Role of Sensory Nerves in Pulmonary Fibrosis.

Pulmonary fibrosis results from the deposition and proliferation of extracellular matrix components in the lungs. Despite being an airway disorder, pulmonary fibrosis also has notable effects on the pulmonary vasculature, with the development and severity of pulmonary hypertension tied closely to patient mortality. Furthermore, the anatomical proximity of blood vessels, the alveolar epithelium, lymphatic tissue, and airway spaces highlights the need to identify shared pathogenic mechanisms and pleiotropic signaling across various cell types. Sensory nerves and their transmitters have a variety of effects on the various cell types within the lungs; however, their effects on many cell types and functions during pulmonary fibrosis have not yet been investigated. This review highlights the importance of gaining a new understanding of sensory nerve function in the context of pulmonary fibrosis as a potential tool to limit airway and vascular dysfunction.

Modification of brain conductivity in human focal epilepsy: A model-based estimation from stereoelectroencephalography.

We have developed a novel method for estimating brain tissue electrical conductivity using low-intensity pulse stereoelectroencephalography (SEEG) stimulation coupled with biophysical modeling. We evaluated the hypothesis that brain conductivity is correlated with the degree of epileptogenicity in patients with drug-resistant focal epilepsy. We used bipolar low-intensity biphasic pulse stimulation (.2 mA) followed by a postprocessing pipeline for estimating brain conductivity. This processing is based on biophysical modeling of the electrical potential induced in brain tissue between the stimulated contacts in response to pulse stimulation. We estimated the degree of epileptogenicity using a semi-automatic method quantifying the dynamic of fast discharge at seizure onset: the epileptogenicity index (EI). We also investigated how the location of stimulation within specific anatomical brain regions or within lesional tissue impacts brain conductivity. We performed 1034 stimulations of 511 bipolar channels in 16 patients. We found that brain conductivity was lower in the epileptogenic zone (EZ; unpaired median difference = .064, p < .001) and inversely correlated with the epileptogenic index value (p < .001, Spearman rho = -.32). Conductivity values were also influenced by anatomical site, location within lesion, and delay between SEEG electrode implantation and stimulation, and had significant interpatient variability. Mixed model multivariate analysis showed that conductivity is significantly associated with EI (F = 13.45, p < .001), anatomical regions (F = 5.586, p < .001), delay since implantation (F = 14.71, p = .003), and age at SEEG (F = 6.591, p = .027), but not with the type of lesion (F = .372, p = .773) or the delay since last seizure (F = 1.592, p = .235). We provide a novel model-based method for estimating brain conductivity from SEEG low-intensity pulse stimulations. The brain tissue conductivity is lower in EZ as compared to non-EZ. Conductivity also varies significantly across anatomical brain regions. Involved pathophysiological processes may include changes in the extracellular space (especially volume or tortuosity) in epileptic tissue.

Assessment of intraocular pressure changes following intravitreal injections of three anti-VEGF agents

PurposeIntravitreal injection (IVI) of anti-vascular endothelial growth factor (anti-VEGF) agents has emerged as the primary treatment for prevalent retinal diseases. Despite its efficacy, IVI may induce intraocular pressure elevation due to vitreous fluid shifts. This study aims to compare the effects of three distinct anti-VEGF agents on intraocular pressure (IOP) elevation within a single clinic setting. DesignA prospective study, conducted at a single retinal clinic in a tertiary medical center (Tel Aviv Sourasky Medical Centre, Tel-Aviv, Israel). MethodsPatients receiving 3 different anti VEGF medications; bevacizumab, aflibercept, and ranibizumab, were examined. IOP was measured pre- and post-injection using an iCare Pro-tonometer. Demographic parameters and ocular characteristics were collected. ResultsThe study included 195 patients (average age 76.13 years; 100 males, 95 females). The medications administered were aflibercept (N = 70, 35 %), bevacizumab (N = 73, 37.4 %), and ranibizumab (N = 52, 26.7 %). In patients with a normal baseline intraocular pressure, no significant variance was observed in the post-injection versus pre-injection pressure change (delta) across medications. Conversely, in patients with higher pressure (>20 mmHg), aflibercept incited a more substantial increase than bevacizumab or ranibizumab. No correlation emerged between the pressure rise and age or lens status. ConclusionsNo significant difference was found in the increase of intraocular pressure following injection among different medications in patients with low-normal intraocular pressure. However, for patients prone to higher baseline pressure, caution is recommended with aflibercept due to a more pronounced increase. Further research is essential to comprehend the factors influencing pressure increase and their associated clinical implications.

Jugular venous flow dynamics during acute weightlessness.

During spaceflight, fluids shift headward, causing internal jugular vein (IJV) distension and altered hemodynamics, including stasis and retrograde flow, that may increase the risk of thrombosis. This study's purpose was to determine the effects of acute exposure to weightlessness (0-G) on IJV dimensions and flow dynamics. We used two-dimensional (2-D) ultrasound to measure IJV cross-sectional area (CSA) and Doppler ultrasound to characterize venous blood flow patterns in the right and left IJV in 13 healthy participants (6 females) while 1) seated and supine on the ground, 2) supine during 0-G parabolic flight, and 3) supine during level flight (at 1-G). On Earth, in 1-G, moving from seated to supine posture increased CSA in both left (+62 [95% CI: +42 to 81] mm2, P < 0.0001) and right (+86 [95% CI: +58 to 113] mm2, P < 0.00012) IJV. Entry into 0-G further increased IJV CSA in both left (+27 [95% CI: +5 to 48] mm2, P = 0.02) and right (+30 [95% CI: +0.3 to 61] mm2, P = 0.02) relative to supine in 1-G. We observed stagnant flow in the left IJV of one participant during 0-G parabolic flight that remained during level flight but was not present during any imaging during preflight measures in the seated or supine postures; normal venous flow patterns were observed in the right IJV during all conditions in all participants. Alterations to cerebral outflow dynamics in the left IJV can occur during acute exposure to weightlessness and thus, may increase the risk of venous thrombosis during any duration of spaceflight.NEW & NOTEWORTHY The absence of hydrostatic pressure gradients in the vascular system and loss of tissue weight during weightlessness results in altered flow dynamics in the left internal jugular vein in some astronauts that may contribute to an increased risk of thromboembolism during spaceflight. Here, we report that the internal jugular veins distend bilaterally in healthy participants and that flow stasis can occur in the left internal jugular vein during acute weightlessness produced by parabolic flight.

A Slow-Exchange Interstitial Fluid Compartment in Volunteers and Anesthetized Patients: Kinetic Analysis and Physiology.

Physiological studies suggest that the interstitial space contains 2 fluid compartments, but no analysis has been performed to quantify their sizes and turnover rates. Retrospective data were retrieved from 270 experiments where Ringer's solution of between 238 and 2750 mL (mean, 1487 mL) had been administered by intravenous infusion to awake and anesthetized humans (mean age 39 years, 47% females). Urinary excretion and hemoglobin-derived plasma dilution served as input variables in a volume kinetic analysis using mixed-models software. The kinetic analysis successfully separated 2 interstitial fluid compartments. One equilibrated rapidly with the plasma and the other equilibrated slowly. General anesthesia doubled the rate constants for fluid entering these 2 compartments (from 0.072 to 0.155 and from 0.026 to 0.080 min -1 , respectively). The return flows to the plasma were impeded by intensive fluid therapy; the rate constant for the fast-exchange compartment decreased from 0.251 to 0.050 when the infusion time increased from 15 to 60 minutes, and the rate constant for the slow-exchange compartment decreased from 0.019 to 0.005 when the infused volume increased from 500 to 1500 mL. The slow-exchange compartment became disproportionately expanded when larger fluid volumes were infused and even attained an unphysiologically large size when general anesthesia was added, suggesting that the flow of fluid was restrained and not solely determined by hydrostatic and oncotic forces. The dependence of the slow-exchange compartment on general anesthesia, crystalloid infusion rate, and infusion volume all suggest a causal physiological process. Kinetic analysis supported that Ringer's solution distributes in 2 interstitial compartments with different turnover times. The slow compartment became dominant when large amounts of fluid were infused and during general anesthesia. These findings may explain why fluid accumulates in peripheral tissues during surgery and why infused fluid can remain in the body for several days after general anesthesia.

Understanding the complexities of space anaemia in extended space missions: revelations from microgravitational odyssey.

Space travel exposes astronauts to several environmental challenges, including microgravity and radiation exposure. To overcome these stressors, the body undergoes various adaptations such as cardiovascular deconditioning, fluid shifts, metabolic changes, and alterations in the state of the bone marrow. Another area of concern is the potential impact of these adaptations on erythrocyte and haemoglobin concentrations, which can lead to what is commonly referred to as space anaemia or microgravity-induced anaemia. It is known that anaemia may result in impaired physical and cognitive performance, making early detection and management crucial for the health and wellbeing of astronauts during extended space missions. However, the effects and mechanisms of space anaemia are not fully understood, and research is underway to determine the extent to which it poses a challenge to astronauts. Further research is needed to clarify the long-term effects of microgravity on the circulatory system and to investigate possible solutions to address spaceflight-induced anaemia. This article reviews the potential link between spaceflight and anaemia, based on existing evidence from simulated studies (e.g., microgravity and radiation studies) and findings from spaceflight studies (e.g., International Space Station and space shuttle missions).

Impact of head-down-tilt body position on abdomen resistance for urinary bladder monitory applications

Tissue electrical impedance (or bioimpedance) is a quantity related to the passive, frequency-dependent electrical properties of a biological tissue and is a promising modality for continuous monitoring of relative bladder volume and bladder activity. In this study, the impact of body position [specifically 6° head-down tilt (HDT)] intended to induce fluid redistribution and, therefore, result in a change in the electrical resistance of the abdomen is evaluated. The abdomen resistance (10 kHz–100 kHz) of nine healthy young adults was measured before and after 240 min in a 6° HDT position. Over this period, the resistance increase was not statistically significant even though the average bladder volume increased by 506 mL. It was expected that the abdomen resistance would decrease with an increase in bladder volume over this period. The masking of the expected resistance decrease is attributed to the shift in the fluid from the legs/abdomen to the neck/chest caused by the HDT body position over this period. Overall, this suggests that methods to differentiate bladder volume changes from other types of fluid shifts in the body are needed for resistance-based monitoring under free-living conditions.

Acute and short-term fluctuations in gravity are associated with changes in circulatory plasma protein levels

Gravitational changes between micro- and hypergravity cause several adaptations and alterations in the human body. Besides muscular atrophy and immune system impairment, effects on the circulatory system have been described, which can be associated with a wide range of blood biomarker changes. This study examined nine individuals (seven males, two females) during a parabolic flight campaign (PFC). Thirty-one parabolas were performed in one flight day, resulting in ~22 s of microgravity during each parabola. Each participant was subjected to a single flight day with a total of 31 parabolas, totaling 11 min of microgravity during one parabolic flight. Before and after (1 hour (h) and 24 h), the flights blood was sampled to examine potential gravity-induced changes of circulating plasma proteins. Proximity Extension Assay (PEA) offers a proteomic solution, enabling the simultaneous analysis of a wide variety of plasma proteins. From 2925 unique proteins analyzed, 251 (8.58%) proteins demonstrated a differential regulation between baseline, 1 h and 24 h post flight. Pathway analysis indicated that parabolic flights led to altered levels of proteins associated with vesicle organization and apoptosis up to 24 h post microgravity exposure. Varying gravity conditions are associated with poorly understood physiological changes, including stress responses and fluid shifts. We provide a publicly available library of gravity-modulated circulating protein levels illustrating numerous changes in cellular pathways relevant for inter-organ function and communication.

The Effect of Simulated Obstructive Apneas on Mechanical Characteristics of Lower Airways in Individuals with Asthma.

Increased negative intrathoracic pressure that occurs during pharyngeal obstruction can increase thoracic fluid volume that may contribute to lower airway narrowing in individuals with obstructive sleep apnea (OSA) and asthma. Our previous study showed that fluid accumulation in the thorax induced by simulated OSA can increase total respiratory resistance. However, the effect of fluid shift on lower airway narrowing has not been investigated. To examine the effect of fluid accumulation in the thorax on the resistance of the lower airway. Non-asthma participants and individuals with (un)controlled asthma were recruited and underwent a single-day experiment. A catheter with six pressure sensors was inserted through the nose to continuously measure pressure at different sites of the airway, while a pneumotachograph was attached to a mouthpiece to record airflow. To simulate obstructive apneas, participants performed 25 Mueller maneuvers (MMs) while lying supine. Using the recordings of pressure sensor and airflow, total respiratory (RT), lower respiratory components (RL), and upper airway (RUA) resistances were calculated before and after MMs. Generalized estimation equation method was used to find the predictors of RL among variables including age, sex, body mass index, and the effect of MMs and asthma. Eighteen participants were included. Performing MMs significantly increased RT (2.23 ± 2.08 cmH2O/L/s, p = 0.003) and RL (1.52 ± 2.00 cmH2O/L/s, p = 0.023) in participants with asthma, while only RL was increased in non-asthma group (1.96 ± 1.73 cmH2O/L/s, p = 0.039). We found the model with age, and the effect of MMs and asthma severity generated the highest correlation (R2 = 0.69, p < 0.001). We provide evidence that fluid accumulation in the thorax caused by excessive intrathoracic pressure increases RL in both non-asthma and asthma groups. The changes in RL were related to age, having asthma and the effect of simulated OSA. This can explain the interrelationship between OSA and asthma.

Dynamic changes in perivascular space morphology predict signs of spaceflight-associated neuro-ocular syndrome in bed rest

During long-duration spaceflight, astronauts experience headward fluid shifts and expansion of the cerebral perivascular spaces (PVS). A major limitation to our understanding of the changes in brain structure and physiology induced by spaceflight stems from the logistical difficulties of studying astronauts. The current study aimed to determine whether PVS changes also occur on Earth with the spaceflight analog head-down tilt bed rest (HDBR). We examined how the number and morphology of magnetic resonance imaging-visible PVS (MV-PVS) are affected by HDBR with and without elevated carbon dioxide (CO2). These environments mimic the headward fluid shifts, body unloading, and elevated CO2 observed aboard the International Space Station. Additionally, we sought to understand how changes in MV-PVS are associated with signs of Spaceflight Associated Neuro-ocular Syndrome (SANS), ocular structural alterations that can occur with spaceflight. Participants were separated into two bed rest campaigns: HDBR (60 days) and HDBR + CO2 (30 days with elevated ambient CO2). Both groups completed multiple magnetic resonance image acquisitions before, during, and post-bed rest. We found that at the group level, neither spaceflight analog affected MV-PVS quantity or morphology. However, when taking into account SANS status, persons exhibiting signs of SANS showed little or no MV-PVS changes, whereas their No-SANS counterparts showed MV-PVS morphological changes during the HDBR + CO2 campaign. These findings highlight spaceflight analogs as models for inducing changes in MV-PVS and implicate MV-PVS dynamic compliance as a mechanism underlying SANS. These findings may lead to countermeasures to mitigate health risks associated with human spaceflight.

Experimental investigation on the vortex-induced vibration response of a lazy-wave flexible riser filled with different fluid media

This paper reports the experimental results of the vortex-induced vibration (VIV) of a lazy-wave flexible riser filled with different fluid media, including the water and helium as typical liquid and light gas examples. The lazy-wave configuration was produced by mounting a buoyancy module of approximately triple the riser diameter on the one-third of the riser length measured from the riser base. The VIV tests were carried out in the depth-averaged reduced velocity (U¯r) range of 9.32–23.19 using the non-intrusive optical measurement with a couple of high-speed cameras. The experimental results indicate that not only the excited mode of in-plane response but also the response amplitude is significantly adjusted when the internal fluid changes, while the excited mode of the out-of-plane response has no obvious modification. Both the water- and helium-filled risers experience the space-varying dominant frequency. However, the helium-filled riser segment possessing a higher dominant frequency is significantly shortened as compared to the water-filled one. When the internal fluid shifts from water to helium, the in-plane mode transition from the first to second becomes incomplete, and the mode transition becomes smoother as U¯r grows. It is found that the starting position of the mode transition is related to the dominant mode as well as the response direction. Then, the influenced length of the riser response from the buoyancy module and the affecting length of the riser on the buoyancy module response are quantified in terms of the spatial distribution of the dominant frequency in comparison with the natural frequencies. The in-plane response of the helium-filled riser is more vulnerable to the oscillation of the buoyancy module, and hence, the coupling between the in-plane and out-of-plane responses is weaker than the water-filled riser. When the impact of buoyancy module on the riser response is enhanced, the reverse effect is weakened.

Red Blood Cells in the Cerebrospinal Fluid Compartment After Subarachnoid Haemorrhage: Significance and Emerging Therapeutic Strategies.

Subarachnoid haemorrhage (SAH) is a subtype of stroke that predominantly impacts younger individuals. It is associated with high mortality rates and can cause long-term disabilities. This review examines the contribution of the initial blood load and the dynamics of clot clearance to the pathophysiology of SAH and the risk of adverse outcomes. These outcomes include hydrocephalus and delayed cerebral ischaemia (DCI), with a particular focus on the impact of blood located in the cisternal spaces, as opposed to ventricular blood, in the development of DCI. The literature described underscores the prognostic value of haematoma characteristics, such as volume, density, and anatomical location. The limitations of traditional radiographic grading systems are discussed, compared with the more accurate volumetric quantification techniques for predicting patient prognosis. Further, the significance of red blood cells (RBCs) and their breakdown products in secondary brain injury after SAH is explored. The review presents novel interventions designed to accelerate clot clearance or mitigate the effects of toxic byproducts released from erythrolysis in the cerebrospinal fluid following SAH. In conclusion, this review offers deeper insights into the complex dynamics of SAH and discusses the potential pathways available for advancing its management.

Reply to Wostyn, P. Targeting the Cerebrospinal Fluid Compartment in Glaucoma: Still the Dark Side of the Moon? Comment on "Passaro et al. Glaucoma as a Tauopathy-Is It the Missing Piece in the Glaucoma Puzzle? J. Clin. Med. 2023, 12, 6900".

We are grateful to the author of the comment [...].

Cerebrospinal fluid pH regulation.

The cerebrospinal fluid (CSF) fills the brain ventricles and the subarachnoid space surrounding the brain and spinal cord. The fluid compartment of the brain ventricles communicates with the interstitial fluid of the brain across the ependyma. In comparison to blood, the CSF contains very little protein to buffer acid-base challenges. Nevertheless, the CSF responds efficiently to changes in systemic pH by mechanisms that are dependent on the CO2/HCO3- buffer system. This is evident from early studies showing that the CSF secretion is sensitive to inhibitors of acid/base transporters and carbonic anhydrase. The CSF is primarily generated by the choroid plexus, which is a well-vascularized structure arising from the pial lining of the brain ventricles. The epithelial cells of the choroid plexus host a range of acid/base transporters, many of which participate in CSF secretion and most likely contribute to the transport of acid/base equivalents into the ventricles. This review describes the current understanding of the molecular mechanisms in choroid plexus acid/base regulation and the possible role in CSF pH regulation.

A pilot study to assess the effects of preventing fluid retention in the legs by wearing compression stockings on overnight airway narrowing in mild asthma.

Nocturnal asthma is a sign of asthma worsening and could be partially due to more fluid drawn into the thorax during sleep by gravitational force and/or pharyngeal collapse in those with obstructive sleep apnea. Wearing compression stockings during the day reduces fluid shift from the legs to the neck overnight. However, the potential effect of wearing compression stockings to reduce fluid accumulation in the leg and to improve nocturnal small airway narrowing in patients with asthma has not been investigated. This study investigates whether reducing leg fluid volume by wearing compression stockings during the day would attenuate small airway narrowing in patients with asthma before and after sleep. We enrolled 11 participants with asthma. All participants underwent overnight polysomnography with or without wearing compression stockings for 2weeks. Before and after sleep, leg fluid volume (LFV) was measured by bioelectrical impedance, and airway narrowing was primarily assessed by respiratory system resistance and reactance at 5Hz (R5 and X5 respectively) using oscillometry. After 2weeks of wearing compression stockings, the LFV measured in the evening was reduced (∆ = - 192.6 ± 248.3ml, p = 0.02), and R5 and X5 improved (∆ = - 0.7 ± 0.9 cmH2O/L/s, p = 0.03 and 0.2 ± 1.4 cmH2O/L/s, p = 0.05 respectively). No changes were observed in the morning. Preventing fluid retention in the legs by wearing compression stockings for 2weeks during the day, reduced LFV and airway narrowing in the evening in all participants with asthma, but not in the morning after sleep.

Development of optic disc edema during 30 days of hypercapnic head-down tilt bed rest is associated with short sleep duration and blunted temperature amplitude.

Sleep and circadian temperature disturbances occur with spaceflight and may, in part, result from the chronically elevated carbon dioxide (CO2) levels on the international space station. Impaired sleep may contribute to decreased glymphatic clearance and, when combined with the chronic headward fluid shift during actual spaceflight or the spaceflight analog head-down tilt bed rest (HDTBR), may contribute to the development of optic disc edema. We determined if strict HDTBR combined with mildly elevated CO2 levels influenced sleep and core temperature and was associated with the development of optic disc edema. Healthy participants (5 females) aged 25-50 yr, underwent 30 days of strict 6° HDTBR with ambient Pco2 = 4 mmHg. Measures of sleep, 24-h core temperature, overnight transcutaneous CO2, and Frisén grade edema were made pre-HDTBR, on HDTBR days 4, 17, 28, and post-HDTBR days 4 and 10. During all HDTBR time points, sleep, core temperature, and overnight transcutaneous CO2 were not different than the pre-HDTBR measurements. However, independent of the HDTBR intervention, the odds ratios {mean [95% confidence interval (CI)]} for developing Frisén grade optic disc edema were statistically significant for each hour below the mean total sleep time (2.2 [1.1-4.4]) and stage 2 nonrapid eye movement (NREM) sleep (4.8 [1.3-18.6]), and above the mean for wake after sleep onset (3.6 [1.2-10.6]) and for each 0.1°C decrease in core temperature amplitude below the mean (4.0 [1.4-11.7]). These data suggest that optic disc edema occurring during HDTBR was more likely to occur in those with short sleep duration and/or blunted temperature amplitude.NEW & NOTEWORTHY We determined that sleep and 24-h core body temperature were unaltered by 30 days exposure to the spaceflight analog strict 6° head-down tilt bed rest (HDTBR) in a 0.5% CO2 environment. However, shorter sleep duration, greater wake after sleep onset, and lower core temperature amplitude present throughout the study were associated with the development of optic disc edema, a key finding of spaceflight-associated neuro-ocular syndrome.

Spinal ependymal tumors.

Spinal ependymomas are strictly to be subdivided into intramedullary lesions and extramedullary lesions as they are histologically and genetically distinct. Whereas the intramedullary lesions (SPE) are assigned to the WHO grade 2 and very rarely grade 3, the extramedullary lesions or myxopapilary tumors (MPE) are only as recently also assigned to WHO grade 2. The major difference is that in general, an intramedullary lesion of grade 2 remains confined to the local site of origin, even when rarely recurring after complete resection. In contrast, the MPEs have the capacity to spread throughout the cerebrospinal fluid compartment but can also be controlled by cautious complete resection. We here review the clinical features of spinal ependymomas, contrasting the entities, and describe the treatment found best from the literature to manage these lesions including interdisciplinary approaches.

Dyselectrolytemia in Children With Severe Pneumonia: A Prospective Study.

Background Pneumonia is a condition characterized by inflammation of the lung parenchyma. It is one of the leading causes of mortality in children below five years of age. While predominantly prevalent in developing countries, it is also associated with significant healthcare-associated costs in developed countries. Among the many risk factors for childhood pneumonia, incomplete immunization, nonexclusive breastfeeding for less than six months, delayed weaning, poor household air quality, malnutrition, and low birth weight are the most commonly found. Electrolyte disturbances, also known as dyselectrolytemia, have been associated with a broad spectrum of acute infections, including pneumonia, particularly hyponatremia. It occurs in the majority of community-acquired pneumonia. Hyper- and hypokalemia are less frequently occurring electrolyte disturbances. Electrolyte disturbances are due to impairment of the intrarenal mechanism of urine dilutiondue to extracellular fluid volume depletion and inappropriate secretion of antidiuretic hormone. The central nervous system is imminently affected by acute hyponatremia. This condition frequently culminates in cerebral edema, a result of the rapid fluid shift, and causes sudden fatality. Aim of the study This study aims to study dyselectrolytemia in children with severe pneumonia. Objectives The study objectives are to assess dyselectrolytemia in children with severe pneumonia and to correlate dyselectrolytemia with morbidity and hospital stay. Methodology This prospective study was conducted on 80 children in the age group of two months up to five years who visited our tertiary care center and had severe pneumonia. We evaluated the extent of dyselectrolytemia in our study population by analyzing the frequency correlation of different kinds of electrolyte imbalances. We also analyzed the correlation between morbidity and hospital stay. Results Out of 80 children in this study with severe pneumonia, 47 (59%) had electrolyte imbalance. Among the patients with electrolyte imbalance, 31 (39%) patients had hyponatremia followed by hypokalemia in 12 (15%) patients, hypernatremia in 3 (4%) patients, and hyperkalemia in 1 (1%) patient. Among the 17 (21%) children with pneumonia requiring ICU admission, 16 (94%) had dyselectrolytemia and 4 (24%) experienced fatal outcomes. Conclusions The majority of the children who were admitted to the ICU had severe pneumonia along with electrolyte imbalance. This necessitates the monitoring of the electrolyte and nutritional status of the patients with pneumonia. Providing proper nutrition advice for children with pneumonia may reduce morbidity and mortality. Early detection and treatment of electrolyte imbalances in pneumonia cases can decrease prolonged hospital stays, ICU admissions, and the need for mechanical ventilation, ultimately contributing to a reduction in morbidity and mortality.