Economic impact of metagenomic next-generation sequencing versus traditional bacterial culture for postoperative central nervous system infections using a decision analysis mode: study protocol for a randomized controlled trial.

IMPORTANCE: Diagnosing and treating postoperative central nervous system infections (PCNSIs) remains challenging due to the low detection rate and time-consuming nature of traditional methods for identifying microorganisms in cerebrospinal fluid. Metagenomic next-generation sequencing (mNGS) technology provides a rapid and comprehensive understanding of microbial composition in PCNSIs by swiftly sequencing and analyzing the microbial genome. The current study aimed to assess the economic impact of using mNGS versus traditional bacterial culture-directed PCNSIs diagnosis and therapy in post-neurosurgical patients from Beijing Tiantan Hospital. mNGS is a relatively expensive test item, and whether it has the corresponding health-economic significance in the clinical application of diagnosing intracranial infection has not been studied clearly. Therefore, the investigators hope to explore the clinical application value of mNGS detection in PCNSIs after neurosurgery.

Association of preoperative frailty with postoperative delirium after elective brain tumor resection: Retrospective analysis of a prospective cohort.

BACKGROUND: Preoperative frailty is associated with poor outcomes in major surgery. Postoperative delirium is common after neurosurgery. To date, the association of preoperative frailty with postoperative delirium after neurosurgery has not been established. We aimed to determine the association between preoperative frailty and postoperative delirium in patients undergoing elective brain tumor resection. METHODS: We retrospectively analyzed the data of a prospective cohort, consecutively enrolling adult patients admitted to the intensive care unit after elective craniotomy for brain tumor resection under general anesthesia in a tertiary hospital in China from March 1, 2017 to February 2, 2018. Preoperative frailty was evaluated using the modified frailty index. The primary outcome was postoperative delirium, assessed using the Confusion Assessment Method for the Intensive Care Unit. Univariate and multivariable regression analyses were performed to examine the association. RESULTS: 659 patients met inclusion criteria for our analysis. There were 398 (60.4%) non-frail (modified frailty index = 0), 237 (36.0%) pre-frail (modified frailty index = 1-2), and 24 (3.6%) frail (modified frailty index ≥ 3) patients. Of these, 124 (18.8%) developed postoperative delirium. In adjusted analyses, frailty was independently associated with postoperative delirium (odds ratio 1.7, 95% confidence interval 1.0-2.7, P = .032). Frail patients had longer length of hospital stay and higher total costs than non-frail patients. CONCLUSION: Preoperative frailty is associated with postoperative delirium, length of hospital stay, and total costs in patients undergoing elective brain tumor resection. Preoperative frailty assessment and appropriate management strategies should be involved in the perioperative management of postoperative delirium.

Derecruitment volume assessment derived from pressure-impedance curves with electrical impedance tomography in experimental acute lung injury.

OBJECTIVE: To investigate the accuracy of derecruitment volume (VDER) assessed by pressure-impedance (P-I) curves derived from electrical impedance tomography (EIT). METHODS: Six pigs with acute lung injury received decremental positive end-expiratory pressure (PEEP) from 15 to 0 in steps of 5 cmH2O. At the end of each PEEP level, the pressure-volume (P-V) curves were plotted using the low constant flow method and release maneuvers to calculate the VDER between the PEEP of setting levels and 0 cmH2O (VDER-PV). The VDER derived from P-I curves that were recorded simultaneously using EIT was the difference in impedance at the same pressure multiplied by the ratio of tidal volume and corresponding tidal impedance (VDER-PI). The regional P-I curves obtained by EIT were used to estimate VDER in the dependent and nondependent lung. RESULTS: The global lung VDER-PV and VDER-PI showed close correlations (r = 0.948, P<0.001); the mean difference was 48 mL with limits of agreement of -133 to 229 mL. Lung derecruitment extended into the whole process of decremental PEEP levels but was unevenly distributed in different lung regions. CONCLUSIONS: P-I curves derived from EIT can assess VDER and provide a promising method to estimate regional lung derecruitment at the bedside.

Noninvasive assessment of airflows by electrical impedance tomography in intubated hypoxemic patients: an exploratory study.

BACKGROUND: Noninvasive monitoring of maximal inspiratory and expiratory flows (MIF and MEF, respectively) by electrical impedance tomography (EIT) might enable early recognition of changes in the mechanical properties of the respiratory system due to new conditions or in response to treatments. We aimed to validate EIT-based measures of MIF and MEF against spirometry in intubated hypoxemic patients during controlled ventilation and spontaneous breathing. Moreover, regional distribution of maximal airflows might interact with lung pathology and increase the risk of additional ventilation injury. Thus, we also aimed to describe the effects of mechanical ventilation settings on regional MIF and MEF. METHODS: We performed a new analysis of data from two prospective, randomized, crossover studies. We included intubated patients admitted to the intensive care unit with acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS) undergoing pressure support ventilation (PSV, n = 10) and volume-controlled ventilation (VCV, n = 20). We measured MIF and MEF by spirometry and EIT during six different combinations of ventilation settings: higher vs. lower support during PSV and higher vs. lower positive end-expiratory pressure (PEEP) during both PSV and VCV. Regional airflows were assessed by EIT in dependent and non-dependent lung regions, too. RESULTS: MIF and MEF measured by EIT were tightly correlated with those measured by spirometry during all conditions (range of R2 0.629-0.776 and R2 0.606-0.772, respectively, p < 0.05 for all), with clinically acceptable limits of agreement. Higher PEEP significantly improved homogeneity in the regional distribution of MIF and MEF during volume-controlled ventilation, by increasing airflows in the dependent lung regions and lowering them in the non-dependent ones. CONCLUSIONS: EIT provides accurate noninvasive monitoring of MIF and MEF. The present study also generates the hypothesis that EIT could guide PSV and PEEP settings aimed to increase homogeneity of distending and deflating regional airflows.