Objectives The purpose of this study was to evaluate the predictive value of the cough peak flow (CPF) for successful extubation in postcraniotomy critically ill patients.Design This was a single-centre prospective diagnostic study.Setting The study was conducted in three intensive care units (ICUs) of a teaching hospital.Participants Postcraniotomy patients who were 18 years or older, stayed in ICU for more than 24 hours and underwent mechanical ventilation for more than 24 hours were eligible for the study. Patients were excluded if one of the following was present: no extubation attempt during the ICU stay; underwent tracheostomy without extubation attempt; pregnant or lactating women; enrolled in other clinical trials; declined to participate in the study. A total of 4879 patients were screened and 1037 were eligible for the study, among whom 785 were included in the study.Outcome measures CPF, including involuntary (CPF-invol) and voluntary CPF (CPF-vol), were measured before extubation. The area under the receiver operating characteristic curve (AUC) was calculated to explore the diagnostic accuracy of CPF in predicting successful extubation.Results There were 641 successful extubation cases (81.7%). The AUC of CPF-invol for predicting successful extubation was 0.810 (95% CI 0.766 to 0.854), with a cut-off value of 63.2 L/min, a sensitivity of 87.4% and a specificity of 66.7%. For conscious patients, the AUC of CPF-invol for the prediction of successful extubation was 0.849 (95% CI 0.794 to 0.904), with a cut-off value of 63.2 L/min and the AUC of CPF-vol was 0.756 (95% CI 0.696 to 0.817), with a cut-off value of 68.2 L/min.Conclusions The CPF was much higher in patients with successful extubation than that in patients with failed extubation. CPF might be valuable for the prediction of extubation outcomes in postcraniotomy critically ill patients. Multicentre studies could be carried out to further validate the results of this study.Trial registration number NCT04000997.

Objective:To investigate the effect of trigger sensitivity on ventilation homogeneity in patients under pressure support ventilation.Methods:We prospectively enrolled 20 patients with heterogeneous lung ventilation under pressure support ventilation that was defined by electrical impedance tomography as the distribution of tidal volume in dependent region lower than 45%. The low and high flow trigger sensitivity (the lowest and highest limits of Servo-i were 2 L/min and 0.2 L/min, respectively) were randomly applied for 20 mins. The distribution of tidal volume in dependent region and end-expiratory lung volume (EELV) were evaluated by electrical impedance tomography. The esophageal manometry was used to measure the inspiratory effort and work of breathing.Results:Comparing to the high trigger sensitivity, the low trigger sensitivity increased the relative distribution of tidal volume in dependent region [(33 ± 9)% vs. (36 ± 9)%, t = 3.735, P = 0.001], the esophageal pressure swings during inspiration [0.8 (0.4, 1.8) cmH2O vs. 1.6 (1.0, 2.1) cmH2O, Z = 2.722, P = 0.021], and pressure time product [29 (15, 54) cmH2O·s-1·min-1 vs. 48 (23, 74) cmH2O·s-1·min-1, Z = 3.298, P = 0.044]; whereas, the change of transpulmonary pressure did not significantly increase [(12.6 ± 4.3) cmH2O vs. (12.8 ± 4.2) cmH2O, t = 0.906, P = 0.376]. The global EELV of a low trigger sensitivity during pressure support ventilation was 78 (29, 170) mL, which mainly acted on the dependent region [75 (-6, 131) mL].Conclusion:Decreasing trigger sensitivity could allow more air to flow into the dependent lung region and improve homogeneity during pressure support ventilation by increasing inspiratory effort, while the working of breathing and transpulmonary pressure remain within acceptable ranges.

BackgroundData concerning the epidemiology of sepsis in critically ill post-craniotomy patients are scarce. This study aimed to assess the incidence, risk factors, and outcomes of sepsis in this population.MethodsThis was a single-center prospective cohort study. Post-craniotomy patients admitted to the intensive care unit (ICU) were screened daily for the presence of infection and sepsis.ResultsOf the 900 included patients, 300 developed sepsis. The cumulative incidence of sepsis was 33.3% [95% confidence interval (CI), 30.2–36.4%]. Advanced age, male, hypertension, trauma, postoperative intracranial complications, and lower Glasgow Coma Scale (GCS) on the first postoperative day were independent risk factors of sepsis. Septic patients had higher hospital mortality (13.7 vs. 8.3%, P = 0.012), longer ICU length of stay (LOS) (14 vs. 4 days, P < 0.001), longer hospital LOS (31 vs. 19 days, P < 0.001), and higher total medical cost (CNY 138,394 vs. 75,918, P < 0.001) than patients without sepsis.ConclusionSepsis is a frequent complication in critically ill post-craniotomy patients. Advanced age, male, hypertension, trauma, postoperative intracranial complications, and lower GCS on the first postoperative day were independent risk factors of sepsis.

Introduction Rapid, sensitive, and specific laboratory assays are critical for the diagnosis and management of central nervous system (CNS) infections. The purpose of this study is to explore the intellectual landscape of research investigating methods for the detection of pathogens in patients with CNS infections and to identify the development trends and research frontier in this field. Methods A bibliometric study is conducted by analyzing literature retrieved from the Web of Science (WoS) Core Collection Database for the years 2000 to 2021. CiteSpace software is used for bibliometric analysis and network visualization, including co-citation analysis of references, co-occurrence analysis of keywords, and cooperation network analysis of authors, institutions, and countries/regions. Results A total of 2,282 publications are eventually screened, with an upward trend in the number of publications per year. The majority of papers are attributed to the disciplines of MICROBIOLOGY, INFECTIOUS DISEASES, IMMUNOLOGY, NEUROSCIENCES & NEUROLOGY, and VIROLOGY. The co-citation analysis of references shows that recent research has focused on the largest cluster “metagenomic next-generation sequencing”; the results of the analysis of the highest-cited publications and the citation burst of publications reveal that there is a strong interest stimulated in metagenomic next-generation sequencing. The co-occurrence analysis of keywords indicates that “infection”, “pathogen”, “diagnosis”, “gene”, “virus”, “polymerase chain reaction”, “cerebrospinal fluid”, “epidemiology”, and “metagenomic next-generation sequencing” are the main research priorities in the field of pathogen detection for CNS infections, and the keyword with the highest strength of burst is “metagenomic next-generation sequencing”. Collaborative network analysis reveals that the USA, the Centers for Disease Control and Prevention of USA, and XIN WANG and JENNIFER DIEN BARD are the most influential country, institution, and researchers, respectively. Conclusions Exploring more advanced laboratory assays to improve the diagnostic accuracy of pathogens is essential for CNS infection research. Metagenomic next-generation sequencing is emerging as a novel useful unbiased approach for diagnosing infectious diseases of the CNS.

Background: Postoperative delirium (POD) is a significant clinical problem in neurosurgical patients after intracranial surgery. Identification of high-risk patients may optimise individual perioperative management, but an adequate and simple risk model for use at super early phase after operation has not been developed. Methods: Adult patients were admitted to the ICU after elective intracranial surgery under general anaesthesia. The POD was diagnosed as Confusion Assessment Method for the ICU positive on postoperative day 1 to 3. Multivariate logistic regression analysis was used to develop the early prediction model (E-PREPOD-NS) and the final model was validated with 200 bootstrap samples. Results: Among 800 patients included in the study, POD occurred in 157 cases (19.6%). We identified nine variables independently associated with POD in the final E-PREPOD-NS model: age > 65 years [odds ratio (OR) = 3.336, 95% confidence interval (CI) = 1.765-6.305, 1 risk score point], education level < 9 years (OR = 2.528, 95% CI = 1.446-4.419, 1 point), history of smoking (OR = 2.582, 95% CI = 1.611-4.140, 1 point), history of diabetes (OR = 2.541, 95% CI = 1.201-5.377, 1 point), supra-tentorial lesions (OR = 3.424, 95% CI = 2.021-5.802, 1 point), anesthesia duration > 360 min (OR = 1.686, 95% CI = 1.062-2.674, 0.5 point), GCS <9 at ICU admission (OR = 6.059, 95% CI = 3.789-9.690, 1.5 points), metabolic acidosis (OR = 13.903, 95% CI = 6.248-30.938, 2.5 points), and positioning of neurosurgical drainage tube (OR = 1.924, 95% CI = 1.132-3.269, 0.5 point). The area under the receiver operator curve (AUROC) of the risk score for prediction of POD was 0.865 (95% CI = 0.835-0.895). After internal validation by bootstrap, the AUROC was 0.851 (95% CI = 0.791-0.912). The model showed good calibration (Hosmer-Lemeshow P = 0.593). Conclusions: The E-PREPOD-NS model based on nine perioperative risk factors can predict POD in patients admitted to the ICU after elective intracranial surgery with fairly good accuracy. External validation is needed before use in clinical practice.

Background Spontaneous breathing trials (SBTs) have been shown to improve outcomes in critically ill patients. However, in patients with brain injury, indications for intubation and mechanical ventilation are different from those of non-neurological patients, and the role of an SBT in patients with brain injury is less established. The aim of the present study was to compare key respiratory variables acquired during a successful SBT between patients with successful ventilator liberation versus failed ventilator liberation. Methods In this prospective study, patients with brain injury (≥18 years of age), who completed a 30-min SBT, were enrolled. Airway pressure, flow, esophageal pressure, and diaphragm electrical activity (ΔEAdi) were recorded before (baseline) and during the SBT. Respiratory rate (RR), tidal volume, inspiratory muscle pressure (ΔPmus), ΔEAdi, and neuromechanical efficiency (ΔPmus/ΔEAdi) of the diaphragm were calculated breath by breath and compared between the liberation success and failure groups. Failed liberation was defined as the need for invasive ventilator assistance within 48 h after the SBT. Results In total, 46 patients (51.9±13.2 years, 67.4% male) completed the SBT. Seventeen (37%) patients failed ventilator liberation within 48 h. Another 11 patients required invasive ventilation within 7 days after completing the SBT. There were no differences in baseline characteristics between the success and failed groups. In-depth analysis showed similar changes in patterns and values of respiratory physiological parameters between the groups. Conclusions In patients with brain injury, ventilator liberation failure was common after successful SBT. In-depth physiological analysis during the SBT did not provide data to predict successful liberation in these patients. Trial registration The trial was registered at ClinicalTrials.gov (No. NCT02863237).

Background : Data about the epidemiology of sepsis in post-craniotomy critical ill patients are scarce. This study aims to assess the incidence, risk factors, and outcomes of sepsis in this population. Methods : We conducted a prospective cohort study between January 1, 2017, and December 31, 2018, in the intensive care unit (ICU) of Beijing Tiantan Hospital. Patients admitted to ICU after intracranial operations and meeting the inclusion criteria were screened daily for the presence of infection and sepsis. We also collected demographics, primary diagnosis, chronic comorbidities, information about surgery, infection, and patients’ outcomes. Results : Of the 900 included patients, 509 (56.6%) were with infection, and 300 developed sepsis. The cumulative incidence of sepsis was 33.3% [95% CI, 30.2%-36.4%]. Male sex, older in age, supratentorial surgery, the sellar region tumors, postoperative hydrocephalus, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score, higher Sequential Organ Failure Assessment (SOFA) score, and lower Glasgow Coma Scale (GCS) were independent risk factors of sepsis. Sepsis was associated with a higher hospital mortality rate (13.7% vs. 8.3%, p =0.012), lower Glasgow Outcome Scale (GOS) at discharge (3 vs. 4, p<0.001), longer ICU length of stay (LOS) (14 vs. 4 days, p<0.001), longer hospital LOS (31 vs. 19 days, p<0.001), and higher total medical costs (RMB 138,394 vs 75,918 Yuan, p<0.001). Conclusions: Sepsis is a frequent complication in post-craniotomy critical ill patients, and is associated with increased hospital mortality rate, increased hospital costs, prolonged ICU LOS, and hospital LOS. Trial registration: Clinicaltrials.gov number: NCT03803813

STUDY OBJECTIVE:To determine the association between postoperative delirium (POD) and cognitive outcomes at least 1 month after surgery in elderly patients, and synthesize the dynamic risk trajectory of cognition impairment after POD. DESIGN:Meta-analysis searching PubMed, Cochrane and EMBASE from inception to November 1, 2020. The terms postoperative delirium, delirium after surgery, postsurgical delirium, postoperative cogniti*, postoperative cognitive dysfunction, postoperative cognition decline, cognitive decline, cognitive impair* and dement* were searched alone or in combination. MEASUREMENTS:Inclusion criteria were prospective cohort studies investigating the association between POD and cognitive outcomes in patients aged ≥60 years underwent surgery. The primary outcome was the association between POD and cognitive outcomes at 1 or more months after surgery. We considered cognitive outcomes measured up to 12 months after surgery as short-term and beyond 12 months as long-term. Two authors performed the study screening, data extraction and quality assessments. Effect sizes were calculated as Hedges g or Odds ratio (OR) based on random- and fixed-effects models. Meta-regression was conducted to analyze the role of potential contributors to heterogeneity. MAIN RESULTS:Eighteen studies were included. Our result showed a significant and medium association between POD and cognitive outcomes after at least 1 month postoperatively (g = 0.61 95% CI 0.43-0.79; I2 = 65.1%), indicating that patients with POD were associated with worse cognitive outcomes. The association of POD with short- and long-term cognitive impairment were also both significant (short-term: g = 0.46 95% CI 0.24-0.68; I2 = 53.1%; and long-term: g = 0.82 95% CI 0.57-1.06; I2 = 57.1%). A multivariate meta-regression suggested that age and measure of delirium were significant sources of heterogeneity. POD was also associated with the significant risk for dementia (OR = 6.08 95% CI 3.80-9.72; I2 = 0) as well as attention (OR = 1.74 95% CI 1.13-2.68; I2 = 0), executive (OR = 1.33 95% CI 1.00-1.80; I2 = 0) and memory impairment (OR = 1.59 95% CI 1.20-2.10; I2 = 43.0%). Additionally, our results showed that the risk trajectory for cognitive decline associated with POD within five years after surgery revealed exponential growth. CONCLUSIONS:This is the first meta-analysis quantifying the association between POD and cognitive outcomes. Our results showed that POD was significantly associated with worse cognitive outcomes, including short- and long-term cognitive outcomes following surgery.

We evaluated the association between the timing of tracheostomy and clinical outcomes in patients with infratentorial lesions. We performed a retrospective observational cohort study in a neurosurgical intensive care unit (ICU) at a tertiary academic medical center from January 2014 to December 2018. Consecutive adult patients admitted to the ICU who underwent resection of infratentorial lesions as well as tracheostomy were included for analysis. Early tracheostomy was defined as performed on postoperative days 1-10 and late tracheostomy on days 10-20 after operation. Univariate and multivariate analyses were used to compare the characteristics and outcomes between both cohorts. A total of 143 patients were identified, and 96 patients received early tracheostomy. Multivariable analysis identified early tracheostomy as an independent variable associated with lower occurrence of pneumonia (odds ratio, 0.25; 95% CI, 0.09-0.73;p = 0.011), shorter stays in ICUs (hazard ratio, 0.4; 95% CI, 0.3-0.6;p = 0.03), and earlier decannulation (hazard ratio, 0.5; 95% CI, 0.4-0.8;p = 0.003). However, no significant differences were observed between the early and late tracheostomy groups regarding hospital mortality (p > 0.999) and the modified Rankin scale after 6 months (p = 0.543). We also identified postoperative brainstem deficits, including cough, swallowing attempts, and extended tongue as well as GCS < 8 at ICU admission as the risk factors independently associated with patients underwent tracheostomy. There is a significant association between early tracheostomy and beneficial clinical outcomes or reduced adverse event occurrence in patients with infratentorial lesions.

Objective:To analyze the incidence and risk factors of postoperative delirium (POD) in patients with glioma and to explore the association between WHO (World Health Organization) tumor grades and POD.Methods:A second analysis of clinical data from 113 adult glioma patients in a single-center, prospective cohort study of 800 neurosurgery patients was conducted from March 2017 to February 2018 at Department of Critical Medicine (ICU), Beijing Tiantan Hospital, Capital Medical University. Patients were assessed for delirium on the first to third days post surgery (twice a day) using the Richmond Agitation-Sedation Scale (RASS) and Confusion Assessment Method for the ICU (CAM-ICU). The patient was divided into delirium group (43 cases) and non-delirium group (70 cases) by whether the patient had had delirium. We collected the patient’s general preoperative information, preoperative condition, early postoperative clinical data, and neurosurgical specialty data (including WHO grades) as potential risk factors that may be associated with the occurrence of POD. The independent risk factors of POD were identified using multivariate logistic regression analysis. In particular, the relationship between WHO glioma grade and POD was explored.Results:In 113 glioma patients who were admitted to the ICU for routine postoperative monitoring, the incidence of POD was 38.1% (43/113). The incidence of POD in patients with WHO grade Ⅰ-Ⅳ gliomas increased with the increase of the WHO grade: 7.7% (1/13), 14.3% (3/21), 22.7% (5/22) and 63.0% (34/57). Among the potential risk factors, age ( OR=1.08, 95% CI: 1.04-1.13, P<0.001), GCS (Glasgow coma scale) score at admission to ICU ( OR=0.80, 95% CI: 0.71-0.90, P<0.001) and the WHO grade of tumor ( OR=2.01, 95% CI: 1.03-3.92, P=0.041) was independent risk factors for POD. Conclusions:The WHO grade of glioma is an independent risk factor for POD. With the increase of tumor grade, the incidence of POD also increases.

目的 探寻颅脑手术中甘露醇输注时长对血钾浓度和颅内压的影响.方法 选择择期行幕上肿瘤切除术患者65例,采用随机数字表法将其分为2组,在磨骨时开始静脉输注20％甘露醇注射液(1g/kg),一组于15 min内输完(15 min组,32例),另一组于30 min内输完(30 min组,33例).分别于输注前(T0)和输注后的即刻(T1)、15 min(T2)、30 min(T3)、60 min(T4)、120 min(T5)时检测血钾浓度,并于剪开硬脑膜时进行颅内压评分.结果 两组T0时间点间血钾浓度的差异无统计学意义[(3.53±0.25) mmol/L比(3.55±0.26) mmol/L,P＞0.05];在输注甘露醇后两组均出现血钾浓度一过性升高;30 min组高钾血症发生率为6.06％(2/33),15 min组患者均未发生高钾血症;两组间血钾浓度峰值的差异无统计学意义[(3.88±0.36) mmol/L比(4.02±0.55) mmol/L,P＞0.05];然而,15 min组血钾浓度峰值与基础值的差值(△K)显著小于30 min组[(0.38±0.30) mmol/L比(0.55±0.40) mmol/L,P＜0.05].在剪开硬脑膜时,15 min组颅内压评分显著低于30 min组[(1.59±0.67)分比(2.21±0.70)分,P＜0.01].从T0到血钾浓度峰值时,两组液体输入量分别为(695.31±391.31)和(808.79±448.84)mL,差异无统计学意义(P＞0.05);然而,两组尿量分别为(739.62±392.45)和(383.94±286.18) mL,15 min组显著多于30 min组(P＜0.01).结论 在颅脑手术中,在15 min内输完甘露醇可在有效降低患者颅内压的同时减少高钾血症的发生.

BACKGROUND: The dynamic occlusion test is used to guide balloon catheter placement during esophageal pressure (P-es) monitoring. We introduced a cardiac cycle locating method to attenuate the influence of cardiac artifacts on Pes measurement. The aim was to provide a reliable analytic algorithm for the occlusion test. METHODS: Esophageal balloon catheters were placed in subjects receiving pressure support ventilation. During balloon position adjustment, end-expiratory occlusion was performed to induce 3 consecutive inspiratory efforts. Pes and airway pressure (P-aw) data were collected for off-line analysis. For each occluded inspiratory effort, the change in Pes (Delta P-es) was plotted against the change in Paw (Delta P-aw), and the slope of the regression line was calculated. The Delta P-es/Delta P-aw ratio was also measured with the cardiac cycle locating method and peak-to-peak method. Bland-Altman analysis was used to assess the agreement between the Delta P-es/Delta P-aw ratio and the slope. We defined the occlusion test with all fitted slopes for the 3 inspiratory efforts within 0.8 to 1.2 to indicate optimal balloon position; otherwise, the position was deemed non-optimal. Using the slope as the reference, the diagnostic accuracy of the Delta P-es/Delta P-aw ratio in distinguishing the optimal and the non-optimal balloon position was analyzed. RESULTS: A total of 86 occlusion tests containing 258 inspiratory efforts were collected from 15 subjects. The median (interquartile range) slope of Delta P-es versus Delta P-aw plot was 0.85 (0.76, 0.91). Bias (lower and upper limit of agreement) of Delta P-es/Delta P-aw ratio measured by the cardiac cycle locating method and the peak-to-peak method was 0.02 (-0.13 to 0.16) and 0.06 (-0.18 to 0.31), respectively. Forty-five (52.3%) occlusion tests indicated optimal balloon positions. Compared to the peak-to-peak method, the cardiac cycle locating method was more specific in detecting the non-optimal position. CONCLUSIONS: The cardiac cycle locating method provided reliable and precise measurement for the occlusion test. This method can accurately detect non-optimal balloon position during catheter adjustment.

BACKGROUND:Stress index provides a noninvasive approach to detect injurious ventilation patterns and to personalize ventilator settings. Obtaining the stress index (SI), however, requires quantitatively analyzing the shape of pressure-time curve with dedicated instruments or a specific ventilator, which may encumber its clinical implementation. We hypothesized that the SI could be qualitatively determined through a visual inspection of ventilator waveforms. METHODS:Thirty-six adult subjects undergoing volume controlled ventilation without spontaneous breathing were enrolled. For each subject, 2 trained clinicians visually inspected the pressure-time curve directly from the ventilator screen. They then qualitatively categorized the shape of pressure-time curve as linear, a downward concavity, or an upward concavity at the bedside. We simultaneously recorded airway pressure and flow signals using a dedicated instrument. A quantitative off-line analysis was performed to calculate the SI using specific research software. This quantitative analysis of the SI served as the reference method for classifying the shape of the pressure-time curve (ie, linear, a downward concavity, or an upward concavity). We compared the SI categorized by visual inspection with that by the reference. RESULTS:We obtained 200 SI assessments of pressure-time curves, among which 125 (63%) were linear, 55 (27%) were a downward concavity, and 20 (10%) were an upward concavity as determined by the reference method. The overall accuracy of visual inspection and weighted kappa statistic (95% CI) was 93% (88-96%) and 0.88 (0.82-0.94), respectively. The sensitivity and specificity to distinguish a downward concavity from a linear shape were 91% and 98%, respectively. The respective sensitivity and specificity to distinguish an upward concavity from a linear shape were 95% and 95%. CONCLUSIONS:Visual inspection of the pressure-time curve on the ventilator screen is a simple and reliable approach to assess SI at the bedside. This simplification may facilitate the implementation of SI in clinical practice to personalize mechanical ventilation. (ClinicalTrials.gov registration NCT03096106.).

Accurate measurement of esophageal pressure (Pes) depends on proper filling of the balloon. Esophageal wall elastance (Ees) may also influence the measurement. We examined the estimation of balloon-surrounding elastance in a bench model and investigated a simplified calibrating procedure of Pes in a balloon with relatively small volume.

Background: Endotracheal extubation is a painful and stressful procedure. The authors hypothesized that the prophylactic use of remifentanil would attenuate the pain intensity and stress responses resulting from extubation in neurosurgical patients. Materials and Methods: In this prospective, randomized, double-blinded, controlled trial, 160 patients with planned delay ex-tubation after elective intracranial operation were randomized 1: 1 to receive either remifentanil or normal saline (control) before their extubation. The dose regime of remifentanil was a bolus of 0.5 mu g/kg over 1 minute, followed by a continuous in-fusion of 0.05 mu g/kg/min for 20 minutes. The primary outcome was the incidence of severe pain during the periextubation period. Secondary outcomes included changes in the pain intensity and vital signs, failing to pass an extubation evaluation after the study drug infusion, severe adverse events, postextubation complications, and clinical outcomes. Results: Two patients in the remifentanil group did not pass the extubation evaluation. The incidence of severe pain during the periextubation period was significantly lower in the remifentanil group compared with the control group (25.0% vs. 41.3%, P = 0.029). Compared with the control group, the visual analog scale in the remifentanil group was significantly lower after the bolus of remifentanil (12 +/- 18 vs. 25 +/- 27, P = 0.001) and immediately after extubation (19 +/- 25 vs. 34 +/- 30, P = 0.001). There were no significant differences in the vital signs immediately after extubation between the 2 groups (P > 0.05). Conclusions: The prophylactic use of remifentanil decreases the incidence of severe pain. Our preliminary findings merit a larger trial to clarify the effect of the prophylactic use of remifentanil on clinical outcomes and adverse events.

Objective To investigate the clinical feasibility of the injection test for balloon placement during oesophageal pressure measurement in patients without spontaneous breathing. Methods The injection test was performed in 12 mechanically ventilated patients under deep sedation and paralysis. During withdrawal of the balloon from the stomach and air injection into the gastric lumen of the catheter, the presence of the injection test wave in the balloon pressure tracing indicated that the whole balloon was positioned above the lower oesophageal sphincter (LES). The positive pressure occlusion test was performed at different balloon positions. Results In each patient, the injection test wave appeared at a distinct balloon depth, with a mean ± standard deviation of 41.9 ± 3.3 cm and range from 37 cm to 47 cm. The optimal ratio of changes in the balloon and airway pressure (0.8–1.2) during the positive pressure occlusion test was obtained when the balloon was located 5 cm and 10 cm above the LES in nine (75%) and three (25%) patients, respectively. Conclusions The injection test is feasible for identification of the whole balloon position above the LES during passive ventilation. The middle third of the oesophagus might be the optimal balloon position.

Aim: To determine the risk factors for and the incidence, outcomes, and causative pathogens of post-craniotomy intracranial infection (PCII) in patients with brain tumors.Methods: A retrospective study was performed of 5723 patients with brain tumors who were surgically treated between January 2012 and December 2013 in Beijing Tiantan Hospital. The patients' demographics, pathohistological diagnoses, surgical procedures, postoperative variables, causative pathogens, and outcomes were evaluated.Results: The overall incidence of PCII was 6.8%, and 82.1% of all cases were diagnosed within two weeks after the craniotomy. Postoperative administration of antibiotics reduced the incidence of PCII. Independent risk factors included clean-contaminated craniotomy, prolonged operation (> 7 h), external cerebrospinal fluid (CSF) drainage/monitoring device placement, and postoperative CSF leakage. Patients <= 45 years old were more susceptible to infection. Compared with supratentorial tumors, tumors located in the infratentorial or intraventricular regions were more vulnerable to PCII. Gram-positive bacteria were the most common causative pathogens isolated from the CSF samples, accounting for 82.0% of the PCII cases.Conclusions: Risk factors for PCII can be identified early in the perioperative period. These findings raise the possibility of improving the clinical outcomes of patients with brain tumors who undergo craniotomy.

OBJECTIVE To evaluate the safety and feasibility of injection test which is used to locate esophageal balloon catheter. METHODS A prospective study was conducted. The patients undergoing invasive mechanical ventilation (MV) admitted to general intensive care unit (ICU) of Beijing Tiantan Hospital Affiliated to Capital Medical University from May 2015 and March 2017 were enrolled. The commercially available esophageal balloon catheter was modified to perform injection test. The catheter was withdrawn step by step and the injection test was repeated until the presence disturbance wave presented, which indicated that the balloon had just entered the esophagus. The position where disturbance wave appears was named 0 cm. End-expiratory occlusions were performed at the positions of +15, +10, +5, 0, -5, -10 and -15 cm, respectively, and the changes of esophageal pressure (Pes) and airway pressures (Paw) were measured in the spontaneous breathing and passive ventilation, and the ratio between the changes (ΔPes/ΔPaw) was calculated. RESULTS A total of 20 patients were enrolled, of which 15 patients finished both the spontaneous and the passive ventilation parts, and 2 patients finished only the spontaneous part and 3 patients finished only passive part. (1) Disturbance waves could be induced by injection test in all patients. The average depth of disturbance wave in spontaneous breathing was deeper than that in passive ventilation (cm: 42.4±3.8 vs. 41.8±3.3), but there was no significant difference between the two ventilation settings (P = 0.132). No adverse events occurred during the study period. (2) Pes increased with the stepwise withdraw of esophageal catheter, reached the maximal value at +5 cm, and then decreased when the catheter was further withdrawn, no matter in the spontaneous or the passive ventilation. In spontaneous breathing, the ΔPes/ΔPaw was within the ideal range (0.8-1.2) at the positions of 0, -5 and -10 cm. The ΔPes/ΔPaw was closest to unity at the positions of 0 cm (0.98±0.15). The ΔPes/ΔPaw at -15 cm (0.66±0.26) was significantly lower than that at 0 cm (P < 0.05). For passive ventilation, the ΔPes/ΔPaw was within the ideal range at the positions of -5 cm and -10 cm, and the ΔPes/ΔPaw was closest to unity at the positions of -10 cm (0.94±0.12). The ΔPes/ΔPaw at 0 cm and -5 cm was significantly higher than that at -10 cm (1.43±0.31 and 1.12±0.14, respectively); while the ΔPes/ΔPaw at -15 cm (0.68±0.23) was significantly lower than that at -10 cm (all P < 0.01). CONCLUSIONS Ideal position of the esophageal balloon catheter could be determined quickly and easily by using injection test. The method is safe and clinically feasible. Clinical Trial Registration Clinical Trials, NCT02446938.