Postural influence on intracranial fluid dynamics: an overview

Survival analysis of famotidine administration routes in non-traumatic intracerebral hemorrhage patients: based on the MIMIC-IV database

OBJECTIVE

This project aims to compare the survival outcomes of non-traumatic intracerebral hemorrhage (ICH) patients with different famotidine administration routes, and explore the risk factors influencing patients' clinical outcomes.

METHODS

Data of patients admitted to the ICU from 2008 to 2019 and receiving famotidine therapy were collected from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients selected for ICU admission > 1 day and treated with famotidine were divided into the group via intravenous (IV) dosing and the group via non-intravenous (Non-IV) dosing. Cox analysis and bilateral stepwise regression were utilized to determine independent prognostic factors affecting patient survival. Survival of patients on different routes of administration before and after propensity score matching (PSM) was compared using Kaplan - Meier (K-M) survival curves.

RESULTS

This investigation included 351 patients. After PSM was matched with a 1:2 ratio, 109 patients were clustered in the IV group and 84 patients in the Non-IV group. Cox multivariate results uncovered that survival prognosis in ICH patients receiving famotidine was associated with age (HR = 1.031, 95%CI:1.011-1.050, p = 0.002), chloride ion levels (HR = 1.061, 95%CI:1.027-1.096, p < 0.001), blood urea nitrogen (BUN) (HR = 1.034, 95%CI:1.007-1.062, p = 0.012), intracranial pressure (ICP) (HR = 1.059, 95%CI:1.027-1.092, p < 0.001), red blood cell distribution width (RDW) (HR = 1.156, 95%CI:1.030-1.299, p = 0.014), mechanical ventilation (HR = 2.526, 95%CI:1.341-4.760, p = 0.004), antibiotic use (HR = 0.331, 95%CI:0.144-0.759, p = 0.009), and Non-IV route (HR = 0.518, 95%CI:0.283-0.948, p = 0.033). The K-M curve results indicated that the 30-day survival rate of Non-IV group ICH patients was substantially higher than that of IV group patients (before PSM, p = 0.036; after PSM, p = 0.011). In the subgroup analysis of age, ICP, mechanical ventilation, and antibiotic use, there was a great heterogeneity interaction between the administration of famotidine and the 30-day mortality rate (P for interaction < 0.05). The Non-IV route considerably reduced the risk of death in patients with normal ICP (7-15 mmHg) (HR = 0.518, 95%CI:0.283-0.948, p = 0.033).

CONCLUSION

Among ICH patients receiving famotidine, those receiving famotidine via Non-IV have a better 30-day survival rate compared to those receiving IV, especially in patients with normal ICP (7-15 mmHg).

Evaluation of the effect of trendelenburg position duration on intracranial pressure in laparoscopic hysterectomies using ultrasonographic optic nerve sheath diameter measurements

BACKGROUND

During laparoscopic surgery, pneumoperitoneum and Trendelenburg positioning applied to provide better surgical vision can cause many physiological changes as well as an increase in intracranial pressure. However, it has been reported that cerebral autoregulation prevents cerebral edema by regulating this pressure increase. This study aimed to investigate whether the duration of the Trendelenburg position had an effect on the increase in intracranial pressure using ultrasonographic optic nerve sheath diameter (ONSD) measurements.

METHODS

The near infrared spectrometry monitoring of patients undergoing laparoscopic hysterectomy was performed while awake (T0); at the fifth minute after intubation (T1); at the 30th minute (T2), 60th minute (T3), 75th minute (T4), and 90th minute (T5) after placement in the Trendelenburg position; and at the fifth minute after placement in the neutral position (T6).

RESULTS

The study included 25 patients. The measured ONSD values were as follows: T0 right/left, 4.18±0.32/4.18±0.33; T1, 4.75±0.26/4.75±0.25; T2, 5.08±0.19/5.08±0.19; T3, 5.26±0.15/5.26±0.15; T4, 5.36±0.11/5.37±0.12; T5, 5.45±0.09/5.48±0.11; and T6, 4.9±0.24/4.89±0.22 ( p < 0.05 compared with T0). ). No statistical difference was detected in all measurements in terms of MAP, HR and ETCO2 values compared to the T0 value (p > 0.05).

CONCLUSIONS

It was determined that as the Trendelenburg position duration increased, the ONSD values ​​increased. This suggests that as the duration of Trendelenburg positioning and pneumoperitoneum increases, the sustainability of the mechanisms that balance the increase in intracranial pressure becomes insufficient.

TRIAL REGISTRATION

This study was registered at Clinical Trials.gov on 21/09/2023 (registration number NCT06048900).

Rheoencephalography: A non-invasive method for neuromonitoring

In neurocritical care, the gold standard method is intracranial pressure (ICP) monitoring for the patient's lifesaving. Since it is an invasive method, it is desirable to use an alternative, noninvasive technique. The computerized real-time invasive cerebral blood flow (CBF) autoregulation (AR) monitoring calculates the status of CBF AR, called the pressure reactivity index (PRx). Studies documented that the electrical impedance of the head (Rheoencephalography - REG) can detect the status of CBF AR (REGx) and ICP noninvasively. We aimed to test REG to reflect ICP and CBF AR. For nineteen healthy subjects we recorded bipolar bifrontal and bitemporal REG derivations and arm bioimpedance pulses with a 200 Hz sampling rate. The challenges were a 30-second breath-holding and head-down-tilt (HDT - Trendelenburg) position. Data were stored and processed offline. REG pulse wave morphology and REGx were calculated. The most relevant finding was the significant morphological change of the REG pulse waveform (2nd peak increase) during the HDT position. Breath-holding caused REG amplitude increase, but it was not significant. REGx in male and female group averages have similar trends during HDT by indicating the active status of CBF AR. The morphological change of REG pulse wave during HDT position was identical to ICP waveform change during increased ICP, reflecting decreased intracranial compliance. A correlation study between ICP and REG was initiated in neurocritical care patients. The noninvasive REG monitoring would also be useful in space research as well as in military medicine during the transport of wounded service members as well as for fighter pilots to indicate the loss of CBF and consciousness.

A Study on the Effects of Different Positions on the Clinical Prognosis of Patients with Acute Ischemic Stroke

The key to treating Acute Ischemic Stroke (AIS) is to rapidly reopen occluded blood vessels, restore blood flow, and rescue the ischemic penumbra. Treatment methods mainly include thrombolysis, endovascular intervention, etc. However, these treatments are limited by strict time windows and technical conditions. Simpler and more feasible methods to improve cerebral blood flow are currently a hot topic in clinical research. In recent years, several studies have shown that changes in body position can effectively improve cerebral blood flow in patients. However, the effect on the neurological functional prognosis of AIS remains inconclusive. This review has examined the effects of changes in body position on the clinical prognosis of AIS, combining relevant guidelines and the latest research. The study has provided evidence of an improvement in the clinical prognosis of AIS.

A Neuro-Ophthalmologist's Guide to Advances in Intracranial Pressure Measurements

Cerebrospinal fluid disorders have a wide-ranging impact on vision, headache, cognition and a person's quality of life. Due to advances in technology and accessibility, intracranial pressure measurement and monitoring, usually managed by neurosurgeons, are being employed more widely in clinical practice. These developments are of direct importance for Ophthalmologists and Neurologists because the ability to readily measure intracranial pressure can aide management decisions. The aim of this review is to present the emerging evidence for intracranial pressure measurement methods and interpretation that is relevant to Neuro-ophthalmologists.

Influence of head-over-body and body-over-head posture on craniospinal, vascular, and abdominal pressures in an acute ovine in-vivo model

INTRODUCTION

Optimal shunt-based hydrocephalus treatments are heavily influenced by dynamic pressure behaviors between proximal and distal ends of shunt catheters. Posture-dependent craniospinal, arterial, venous, and abdominal dynamics thereby play an essential role.

METHODS

An in-vivo ovine trial (n = 6) was conducted to evaluate communication between craniospinal, arterial, venous, and abdominal dynamics. Tilt-testing was performed between -13° and + 13° at 10-min intervals starting and ending at 0° prone position. Mean pressure, pulse pressure, and Pearson correlation (r) to the respective angle were calculated. Correlations are defined as strong: |r|≥ 0.7, mild: 0.3 <|r|< 0.7, and weak: |r|≤ 0.3. Transfer functions (TFs) between the arterial and adjacent compartments were derived.

RESULTS

Strong correlations were observed between posture and: mean carotid/femoral arterial (r = - 0.97, r = - 0.87), intracranial, intrathecal (r = - 0.98, r = 0.94), jugular (r = - 0.95), abdominal cranial, dorsal, caudal, and intravesical pressure (r = - 0.83, r = 0.84, r = - 0.73, r = 0.99) while mildly positive correlation exists between tilt and central venous pressure (r = 0.65). Only dorsal abdominal pulse pressure yielded a significant correlation to tilt (r = 0.21). TFs followed general lowpass behaviors with resonant peaks at 4.2 ± 0.4 and 11.5 ± 1.5 Hz followed by a mean roll-off of - 15.9 ± 6.0 dB/decade.

CONCLUSIONS

Tilt-tests with multi-compartmental recordings help elucidate craniospinal, arterial, venous, and abdominal dynamics, which is essential to optimize shunt-based therapy. Results motivate hydrostatic influences on mean pressure, with all pressures correlating to posture, with little influence on pulse pressure. TF results quantify the craniospinal, arterial, venous, and abdominal compartments as compliant systems and help pave the road for better quantitative models of the interaction between the craniospinal and adjacent spaces.