Intensive Care Medicine Experimental最新文献

Background: Patients undergoing extended multivisceral, non-cardiac surgery require a high demand for intravenous fluid administration, leading to substantial positive fluid balances. This study aimed to perioperatively characterize extravasation as a correlate of capillary leakage and micro-arterial regulation, as well as venous return characteristics, as possible causes for the positive fluid balances.

Methods: In this single center, observational trial we included patients undergoing abdominal debulking surgery due to ovarian cancer. The measurements were performed by a venous congestion plethysmography (VCP) protocol to determine extravasation, micro-arterial reagibility, and after deflation of congestion venous outflow characteristics at timepoints before and during surgery, and repeatedly during the postoperative course.

Results: Thirty patients with primary ovarian cancer undergoing cytoreductive surgery treated within a goal-directed hemodynamic algorithm (GDA) based on the esophageal Doppler were included in the analysis. Stroke volume index did not change throughout the procedure with an increase in heart rate and consequently an increase in cardiac index. The norepinephrine requirements to maintain mean arterial pressure increased during surgery. Patients received a median 1750[25-quartile 1075;75-quartile 2100]ml crystalloids and 1000[1000;1500]ml starches, transfusions of 0[0;1040]ml red-packed cells, and 360[0;2880]ml fresh-frozen plasma. The intraoperative fluid and blood loss of 1020[508;1695]ml resulted in a positive fluid balance (2820[1338;6075]ml). Extravasation did not increase during surgery, even in the presence of substantially positive fluid balances. On the third and fifth postoperative days, extravasation increased relative to the preoperative baseline value. The micro-arterial function deteriorated throughout the course of the surgery, recovering to baseline values within 4 h after surgery. The venous outflow characteristics of the limb after releasing the venous congestion deteriorated over the course of surgery.

Conclusions: There was no increase in extravasation measured by VCP during surgery despite a substantial intraoperative positive fluid balance, showing that they were not associated with each other. The micro-arterial function and venous backflow characteristics deteriorated during surgery, indicating that vascular dilation rather than capillary leakage may contribute to the high fluid demands.

Trial registration: ClinicalTrials.gov identifier: NCT01311297.

Background: Mechanical ventilation is a critical life support technology in the intensive care unit. However, the weaning process remains complex, making the optimal timing for liberation from ventilation challenging to ascertain and imposing a considerable clinical workload. Additionally, advanced weaning assistance tools that integrate multidimensional clinical factors to help clinical staff make precise decisions during the weaning process are lacking. The aim of this study to develop and validate an interpretable machine learning model that comprehensively evaluates the factors influencing weaning to provide clinical decision support for weaning.

Method: We collected data from the ICU of Shanghai Tenth People's Hospital and its affiliated hospitals. Ten distinct machine learning algorithms for predicting extubation outcomes in patients receiving mechanical ventilation were developed and internally validated. Model performance was quantified using the area under the receiver operating characteristic curve AUC, overall accuracy, sensitivity, specificity, and F1 score. NRI, IDI, and DCA were used to comprehensively identify the optimal model. The relative contribution of each predictor was ranked and compared through SHAP analysis, and the best-performing model was externally validated.

Results: Through univariate and LASSO analyses, 24 predictive variables for machine learning model construction were identified. Comprehensive evaluation showed that among the candidate algorithms, the LGB model demonstrated the highest overall performance. SHAP analysis revealed that the top-ranked features for predicting successful liberation from mechanical ventilation were creatinine levels, lactate levels, the level of consciousness, SpO2, systolic blood pressure, cough reflex, chronic respiratory disease, diastolic blood pressure, and age.

Conclusions: The optimized predictive model, which was developed through the integration of multidimensional predictive factors with diverse machine learning algorithms, exhibits superior predictive accuracy and demonstrates significant clinical potential for determining the optimal timing for weaning patients receiving invasive mechanical ventilation. Trial registration Current Controlled Trials ChiCTR2400093658; registration date: December 10, 2024.

Background: Paradoxical improvement in respiratory system compliance with chest wall loading ('mechanical paradox') has been well described in adult respiratory distress syndrome (ARDS), especially in the setting of severe Covid-19 pneumonia. A standardized bedside technique of chest wall loading to elicit this paradoxical response has not been fully developed.

Methods: In two community ICUs, adult patients who were passively ventilated with volume control for diverse conditions underwent a series of stepwise compression maneuvers: first, manual compressions of the chest and abdomen in the semi-Fowler and supine positions; then, compressions of the chest and abdomen with 2, 6, and 10 kg saline bags in the supine position. These maneuvers were conducted with small and large surface 'footprints'. Under each loading condition, three breath cycles were allowed to pass before tidal volume, PEEP, peak, and plateau pressures were recorded.

Results: Ten patients were included in the case series. Only one of ten patients demonstrated mechanical paradox, which was elicited both by chest wall loading and by moving the patient from the semi-Fowler to the horizontal position. In all patients, abdominal compression elicited a larger change in plateau pressure than did sternal compression. At least 6 kg of weighting force was needed to detect a meaningful change in plateau pressure.

Conclusions: Mechanical paradox occurs infrequently outside of very severe, unresolving ARDS. Apart from compression over the upper abdomen, a simple bedside maneuver for detection of mechanical paradox may be moving the patient from the semi-upright to the supine position.

Introduction: Venous congestion is a major contributor to organ dysfunction in critically ill and perioperative patients. While Doppler-based ultrasound strategies such as VExUS are the focus of growing clinical and research interest, the common femoral vein (CFV) is a promising, easily accessible alternative window for assessing right heart function and volume status.

Objective: To map and synthesize current evidence on the use of common femoral vein (CFV) Doppler ultrasound to assess venous congestion, right heart function, and intravascular volume status in adult patients across perioperative, critical care, heart failure, and emergency care settings.

Design: Scoping review conducted according to the PRISMA-ScR guideline.

Review methods: PubMed, Embase, Scopus, and the Cochrane Library were searched from inception to August 2025. We charted clinical setting, CFV Doppler/diameter parameters, acquisition protocol details, reference standards (invasive pressures and imaging-based surrogates), and reported associations with hemodynamic measures and clinical outcomes. Two reviewers independently screened records and extracted data.

Results: Nineteen observational studies (n = 2146) were included. CFV pulsatility or waveform morphology was assessed in 10/19 studies; 5/19 reported quantitative pulsatility indices or retrograde-flow thresholds, 5/19 evaluated femoral vein diameter/collapsibility, and 1/19 proposed derived indices. Most studies compared CFV measures with invasive central venous pressure (CVP) or echocardiographic surrogates; when correlation coefficients were reported, associations were weak-to-moderate (e.g., r = 0.66 for CFV diameter vs CVP; r = - 0.476 for minimum velocity vs CVP). Only a minority of studies assessed clinical outcomes, and abnormal CFV patterns were variably associated with postoperative complications, including acute kidney injury, delirium and, in ICU cohorts, longer ICU length of stay or mortality. Acquisition protocols and waveform interpretation criteria varied across studies, with heterogeneous definitions and thresholds.

Conclusions: CFV Doppler is a feasible and accessible tool for congestion assessment, with promising correlations to invasive measures. However, variability in acquisition protocols, waveform definitions, and thresholds limits its current applicability. Standardization and prospective validation in high-risk populations are needed.

Background: Dexmedetomidine (DEX) is increasingly used in the intensive care unit for sedation and also serves as an adjuvant in general anesthesia and in procedural sedations. We tested whether dexmedetomidine at different concentrations influences the activity of the neuromuscular junction at the diaphragm and whether DEX has an impact on the action of rocuronium at the diaphragm as well as the reversal of the neuromuscular block by sugammadex.

Methods: 20 male Wistar rat phrenic nerve-hemidiaphragm system was used for our experiments. The concentration-response characteristics of DEX and rocuronium were quantified as the depression of the force amplitude of single twitches (ST) in response to electrical stimulation of the phrenic nerve. Rocuronium concentration-response curves were obtained with 0, 1, and 2.67 μg/ml DEX concentration. After a single dose of rocuronium, sugammadex doses were given until additional doses of sugammadex were not accompanied by a further increase in ST force amplitude. The concentration-response curve of sugammadex was also measured in the presence of 1 μg/ml DEX concentration.

Results: DEX at different doses negligibly reduces the force of the contractions and the contractility of the diaphragm. The EC50 of rocuronium [7.74 µM (6.99-8.57)] did not change significantly [7.18 µM (6.58-7.84); p = 0.27] with the addition of DEX 1 µg/ml. At 2.67 µg/ml DEX concentration, the ED50 of rocuronium was significantly reduced [6.37 µM (5.69-7.13); p = 0.015]. With 1 µg/ml DEX concentration, the EC50 of the sugammadex [2.04 µM (1.94-2.14)] needed for the reversal of rocuronium-induced neuromuscular blockade was significantly increased [2.45 µM (2.39-2.51); p < 0.01].

Conclusions: DEX at clinically administered doses does not significantly influence the function of the neuromuscular junction at the diaphragm. Under routine dosing conditions, the action of the neuromuscular blocking agents and their reversal by sugammadex are also not modified by DEX.

Background: Cardiac arrest (CA) is a major cause of mortality and morbidity. Accurate prediction of neurological outcome and survival remains challenging. In this context, our study aimed to explore novel molecular biomarkers that could provide additional insights into the pathophysiology of brain injury after CA and potentially distinguish patients with no brain injury (CPC 1) from those with any degree of neurological damage from moderate injury up to death (CPC 2-5), and complement existing prognostic tools.

Methods: Whole blood samples collected 48 h after return of spontaneous circulation were analyzed by RNA sequencing in a subgroup of 50 CA patients from the monocenter North Pole cohort, and by quantitative PCR in 233 patients from the same cohort as well as in 511 patients from the multicenter TTM trial. The association of gene expression changes with 6-month neurological outcome (assessed by the Cerebral Performance Category (CPC) score) and survival was studied.

Results: In a discovery phase with a subset of 50 patients from the North Pole cohort (25 CPC 1 and 25 CPC 5), direct RNA sequencing identified the solute carrier family 2 member 1 (SLC2A1), a gene encoding a major glucose transporter at the blood-brain barrier (GLUT1), as significantly upregulated in CPC 5 patients (dead with severe neurological impairment) compared to survivors without neurological sequelae (CPC 1). This upregulation was confirmed by quantitative PCR and extended to the entire North Pole cohort (p < 0.001). SLC2A1 was an independent predictor of neurological sequelae or death in this cohort. In the TTM trial, SLC2A1 was also upregulated in patients with neurological sequelae or death (p < 0.001) and was an independent predictor of neurological sequelae or death, providing an incremental predictive value to a baseline clinical model (odds ratio = 2.06, 95% confidence interval 1.31-3.4, p = 2.82E-03, and likelihood ratio test p < 0.001).

Conclusion: Blood level of SLC2A1 is a tentative blood biomarker that may aid in neurological outcome prediction after CA and also provide new insights into post-CA injury mechanisms.

The achieved technological maturity of electrical impedance tomography (EIT) and the clinical need of the information provided by this functional imaging method has intensified research activities on the medical use of chest EIT. The recent years have witnessed an accelerated research covering not only the experimental setting but also the clinical environment with the major focus on mechanically ventilated patients, both in the perioperative period or as part of the intensive care treatment. Patients of all age groups are being included in clinical investigations and studies using EIT. The major objectives for use of EIT are the monitoring of regional lung and cardiovascular function, identification of adverse events (pneumothorax, alveolar overdistension and collapse, pulmonary embolism) and guidance for individualised therapy (selection of ventilator setting, positioning and physical therapy). Our review describes the most recent achievements of experimental and clinical research on chest EIT. The provided information helps to identify the current hot topics in EIT research and to guide further improvements of EIT technology and applications that are still needed to enforce the establishment of chest EIT in routine patient care.

Background: In mechanically ventilated patients with acute respiratory distress syndrome (ARDS) it is of great importance to prevent ventilator-induced lung injury (VILI) using lung protective ventilation. VILI has been associated with a high mechanical power (MP). Flow-controlled ventilation (FCV) could play a role in decreasing the risk of VILI by lowering the MP and preventing atelectrauma by a controlled expiration.

Objectives: To assess the difference in MP between FCV and pressure-controlled ventilation (PCV). Secondary aims were to explore the effect of FCV in terms of ventilation distribution and homogeneity, measured by electrical impedance tomography (EIT).

Methods: Randomized crossover physiological pilot study in ICU patients with a moderate to severe ARDS. Patients were randomized between 90 min of FCV followed by 90 min of PCV, or vice versa. Intratracheal and esophageal pressure, airway flow and EIT were measured continuously, and hemodynamics and venous and arterial blood gases were obtained repeatedly. Pressure-volume loops were constructed for the calculation of the MP.

Results: In 10 patients, optimized FCV (compliance-guided driving pressure) versus PCV resulted in a similar MP (12.6 vs. 14.8 J/min; p = 0.302). A stable gas exchange at similar minute volumes was obtained. Optimized FCV resulted in increased tidal ventilation of the mid-ventral to dorsal regions compared to PCV, but EIT demonstrated a trend towards overdistension especially of the non-dependent lung regions. Because of this trend towards overdistension, severe hypercapnia in one patient, and inability to apply FCV as intended, the study was stopped early due to safety concerns.

Conclusions: Optimized FCV compared with PCV resulted in a similar MP and tends towards overdistension in patients with moderate to severe ARDS.

Trial registration: Clinicaltrials.gov identifier: NCT06051188. Registered 22 September 2023.