[Determination of polybrominated diphenyl ethers in marine sediments by composite chromatography column purification-gas chromatography-negative chemical ionization-mass spectrometry].

Polybrominated diphenyl ethers (PBDEs) are used as additive flame retardants. Because they lack the ability to form chemical bonds, PBDEs can easily enter the sediment environment. The accurate qualitative and quantitative analysis of PBDEs in sediments is of great importance for the accurate assessment of PBDE pollution in this environment. Sediments contain many impurities. Therefore, PBDEs in sediment should be purified before analysis to reduce the matrix effect. A method based on gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI/MS) was developed to determine 13 PBDEs in marine sediment samples using a column packed with deactivated silica gel, acidified silica gel, Florisil, and anhydrous sodium sulfate. Sediment samples were extracted by ultrasonication with a mixed solvent of n-hexane-dichloromethane (3∶1, v/v). After two cycles of ultrasonic extraction, the extract was purified by a composite chromatographic column and eluted with n-hexane-dichloromethane (3∶1, v/v). Thirteen PBDEs were determined by GC-NCI/MS in selected-ion monitoring (SIM) mode. The effects of different fillers, eluents, and elution volumes on the purification of PBDEs in the composite column were compared and analyzed, and the GC-NCI/MS analysis conditions were optimized. Three different packing columns were used to purify the sample extract. The first column was packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate; the second column was packed with 3 g of Florisil, 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate; and the third column was packed with 3 g of deactivated silica, 6 g of acidified silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate. Among these columns, that packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate showed the best purification effect. The 13 PBDEs showed good linearity in the mass concentration range of 0.1-20 µg/L with correlation coefficients (r2) greater than 0.995 (decabromodiphenyl oxide (BDE-209), r2>0.99). The limits of quantification (S/N=10) was 0.002-0.126 µg/kg. The average recoveries of the 13 PBDEs at three spiked levels of 0.2, 1.0, and 4.0 µg/kg were 85.3%-101.3%, 84.8%-113.6%, and 86.3%-94.7% with relative standard deviations of 4.4%-14.0%, 0.4%-4.9%, and 1.9%-6.6%, respectively. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the analysis and detection of PBDEs in actual marine sediment samples. The results revealed that the sediment samples contained different contents of the 13 PBDEs, and high detection rates were obtained for lower-brominated PBDE homologs. The detection rate of bis(4-bromophenyl) ether (BDE-15) was 100%, and the detected content of BDE-209 was as high as 60.49 µg/kg. These results demonstrate that the developed method is suitable for the accurate qualitative and quantitative analysis of PBDEs in marine sediment samples.

Development of an early prediction model for postoperative delirium in neurosurgical patients admitted to the ICU after elective craniotomy (E-PREPOD-NS): A secondary analysis of a prospective cohort study.

Postoperative delirium (POD) is a significant clinical problem in neurosurgical patients after intracranial surgery. Identification of high-risk patients may optimize perioperative management, but an adequate risk model for use at early phase after operation has not been developed. In the secondary analysis of a prospective cohort study, 800 adult patients admitted to the ICU after elective intracranial surgeries were included. 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 early prediction model (E-PREPOD-NS) and the final model was validated with 200 bootstrap samples. The incidence of POD in this cohort was19.6%. We identified nine variables independently associated with POD in the final model: advanced age (OR 3.336, CI 1.765-6.305, 1 point), low education level (OR 2.528, 1.446-4.419, 1), smoking history (OR 2.582, 1.611-4.140, 1), diabetes (OR 2.541, 1.201-5.377, 1), supra-tentorial lesions (OR 3.424, 2.021-5.802, 1), anesthesia duration > 360 min (OR 1.686, 1.062-2.674, 0.5), GCS < 9 at ICU admission (OR 6.059, 3.789-9.690, 1.5), metabolic acidosis (OR 13.903, 6.248-30.938, 2.5), and neurosurgical drainage tube (OR 1.924, 1.132-3.269, 0.5). 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). The AUROC was 0.851 after internal validation (95% CI 0.791-0.912). The model showed good calibration. The E-PREPOD-NS model can predict POD in patients admitted to the ICU after elective intracranial surgery with good accuracy. External validation is needed in the future.

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.

Effect of positive end-expiratory pressure on functional residual capacity in two experimental models of acute respiratory distress syndrome.

OBJECTIVE: Measurement of positive end-expiratory pressure (PEEP)-induced recruitment lung volume using passive spirometry is based on the assumption that the functional residual capacity (FRC) is not modified by the PEEP changes. We aimed to investigate the influence of PEEP on FRC in different models of acute respiratory distress syndrome (ARDS). METHODS: A randomized crossover study was performed in 12 pigs. Pulmonary (n = 6) and extra-pulmonary (n = 6) ARDS models were established using an alveolar instillation of hydrochloric acid and a right atrium injection of oleic acid, respectively. Low (5 cmH2O) and high (15 cmH2O) PEEP were randomly applied in each animal. FRC and recruitment volume were determined using the nitrogen wash-in/wash-out technique and release maneuver. RESULTS: FRC was not significantly different between the two PEEP levels in either pulmonary ARDS (299 ± 92 mL and 309 ± 130 mL at 5 and 15 cmH2O, respectively) or extra-pulmonary ARDS (305 ± 143 mL and 328 ± 197 mL at 5 and 15 cmH2O, respectively). The recruitment volume was not significantly different between the two models (pulmonary, 341 ± 100 mL; extra-pulmonary, 351 ± 170 mL). CONCLUSIONS: PEEP did not influence FRC in either the pulmonary or extra-pulmonary ARDS pig model.

Use of Electrical Impedance Tomography (EIT) to Estimate Global and Regional Lung Recruitment Volume (VREC) Induced by Positive End-Expiratory Pressure (PEEP): An Experiment in Pigs with Lung Injury.

BACKGROUND Electrical impedance tomography (EIT) is a real-time tool used to monitor lung volume change at the bedside, which could be used to measure lung recruitment volume (VREC) for setting positive end-expiratory pressure (PEEP). We assessed and compared the agreement in VREC measurement with the EIT method versus the flow-derived method. MATERIAL AND METHODS In 12 Bama pigs, lung injury was induced by tracheal instillation of hydrochloric acid and verified by an arterial partial pressure of oxygen to inspired oxygen fraction ratio below 200 mmHg. During the end-expiratory occlusion, an airway release maneuver was conduct at 5 and 15 cmH2O of PEEP. VREC was measured by flow-integrated PEEP-induced lung volume change (flow-derived method) and end-expiratory lung impedance change (EIT-derived method). Linear regression and Bland-Altman analysis were used to test the correlation and agreement between these 2 measures. RESULTS Lung injury was successfully induced in all the animals. EIT-derived VREC was significantly correlated with flow-derived VREC (R²=0.650, p=0.002). The bias (the lower and upper limits of agreement) was -19 (-182 to 144) ml. The median (interquartile range) of EIT-derived VREC was 322 (218-469) ml, with 110 (59-142) ml and 194 (157-307) ml in dependent and nondependent lung regions, respectively. Global and regional respiratory system compliance increased significantly at high PEEP compared to those at low PEEP. CONCLUSIONS Close correlation and agreement were found between EIT-derived and flow-derived VREC measurements. The advantages of EIT-derived recruitability assessment included the avoidance of ventilation interruption and the ability to provide regional recruitment information.

Incidence and risk factors of postoperative delirium in patients admitted to the ICU after elective intracranial surgery: A prospective cohort study.

BACKGROUND: Postoperative delirium (POD) has been confirmed as an important complication after major surgery. However, neurosurgical patients have usually been excluded in previous studies. To date, data on POD and risk factors in patients after intracranial surgery are scarce. OBJECTIVES: To determine the incidence and risk factors of POD in patients after intracranial surgery. DESIGN: Prospective cohort study. SETTING: A neurosurgical ICU of a university-affiliated hospital, Beijing, China. INTERVENTIONS: Adult patients admitted to the ICU after elective intracranial surgery under general anaesthesia were consecutively enrolled between 1 March 2017 and 2 February 2018. Delirium was assessed using the Confusion Assessment Method for the ICU. POD was diagnosed as Confusion Assessment Method for the ICU positive on either postoperative day 1 or day 3. Patients were classified into groups with or without POD. Data were collected for univariate and multivariate analyses to determine the risk factors for POD. RESULTS: A total of 800 patients were included. POD was diagnosed in 157 patients (19.6%, 95% confidence interval 16.9 to 22.4%). Independent risk factors for POD included age, nature of intracranial lesion, frontal approach craniotomy, duration of surgery, presence of an episode of low pulse oxygenation at ICU admission, presence of inadequate emergence and emergence delirium, postoperative pain and presence of immobilising events. POD was associated with adverse outcomes and high costs. CONCLUSION: POD is prevalent in patients after elective intracranial surgery. The identified risk factors for and the potential association of POD with adverse outcomes suggest that a comprehensive strategy involving screening for predisposing factors and early prevention of modifiable factors should be established in this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT03087838.

Additional Expiratory Resistance Elevates Airway Pressure and Lung Volume during High-Flow Tracheal Oxygen via Tracheostomy.

The standard high-flow tracheal (HFT) interface was modified by adding a 5-cm H2O/L/s resistor to the expiratory port. First, in a test lung simulating spontaneous breathing, we found that the modified HFT caused an elevation in airway pressure as a power function of flow. Then, three tracheal oxygen treatments (T-piece oxygen at 10 L/min, HFT and modified HFT at 40 L/min) were delivered in a random crossover fashion to six tracheostomized pigs before and after the induction of lung injury. The modified HFT induced a significantly higher airway pressure compared with that in either T-piece or HFT (p < 0.001). Expiratory resistance significantly increased during modified HFT (p < 0.05) to a mean value of 4.9 to 6.7 cm H2O/L/s. The modified HFT induced significant augmentation in end-expiratory lung volume (p < 0.05) and improved oxygenation for lung injury model (p = 0.038) compared with the HFT and T-piece. There was no significant difference in esophageal pressure swings, transpulmonary driving pressure or pressure time product among the three treatments (p > 0.05). In conclusion, the modified HFT with additional expiratory resistance generated a clinically relevant elevation in airway pressure and lung volume. Although expiratory resistance increased, inspiratory effort, lung stress and work of breathing remained within an acceptable range.

Epidemiological study on hand, foot and mouth disease in Tongzhou District, Beijing, 2013-2017.

OBJECTIVE: To study the epidemiological characteristics of hand, foot and mouth disease (HFMD) in Tongzhou District, Beijing between 2013 and 2017. METHODS: Data on HFMD infections from 1 January 2013 to 31 December 2017 were collected from the Notifiable Infectious Diseases Reporting Information System and analysed. Serotyping of enteroviruses from samples from patients with HFMD was undertaken using reverse transcription-polymerase chain reaction. RESULTS: A total of 15 341 patients with HFMD were reported and 32 patients (0.2%) were classified as having severe HFMD. The annual mean incidence rate of HFMD was 219.3/100 000 of the general population. The incidence and case-severity rates of HFMD generally decreased between 2013 and 2017. In the floating migrant population, the incidence and cases-severity rates of HFMD were significantly higher than in the local population. The peak incidence and severity-case rates were at 2 years of age and > 90% of patients were ≤5 years. Enterovirus A71 and Coxsackievirus A16 were the predominant pathogens in 2013-2017. CONCLUSIONS: During the 5-year period 2013-2017, the incidence rate and case-severity rate of HFMD generally decreased in Tongzhou District, Beijing. The floating migrant population and children ≤5 years of age were at the highest risk of HFMD.

Bi-frontal pneumocephalus is an independent risk factor for early postoperative agitation in adult patients admitted to intensive care unit after elective craniotomy for brain tumor: A prospective cohort study.

Postoperative agitation frequently occurs after general anesthesia and may be associated with serious consequences. However, studies in neurosurgical patients have been inadequate. We aimed to investigate the incidence and risk factors for early postoperative agitation in patients after craniotomy, specifically focusing on the association between postoperative pneumocephalus and agitation. Adult intensive care unit admitted patients after elective craniotomy under general anesthesia were consecutively enrolled. Patients were assessed using the Sedation-Agitation Scale during the first 24 hours after operation. The patients were divided into two groups based on their maximal Sedation-Agitation Scale: the agitation (Sedation-Agitation Scale ≥ 5) and non-agitation groups (Sedation-Agitation Scale ≤ 4). Preoperative baseline data, intraoperative and intensive care unit admission data were recorded and analyzed. Each patient's computed tomography scan obtained within six hours after operation was retrospectively reviewed. Modified Rankin Scale and hospital length of stay after the surgery were also collected. Of the 400 enrolled patients, agitation occurred in 13.0% (95% confidential interval: 9.7-16.3%). Body mass index, total intravenous anesthesia, intraoperative fluid intake, intraoperative bleeding and transfusion, consciousness after operation, endotracheal intubation kept at intensive care unit admission and mechanical ventilation, hyperglycemia without a history of diabetes, self-reported pain and postoperative bi-frontal pneumocephalus were used to build a multivariable model. Bi-frontal pneumocephalus and delayed extubation after the operation were identified as independent risk factors for postoperative agitation. After adjustment for confounding, postoperative agitation was independently associated with worse neurologic outcome (odd ratio: 5.4, 95% confidential interval: 1.1-28.9, P = 0.048). Our results showed that early postoperative agitation was prevalent among post-craniotomy patients and was associated with adverse outcomes. Improvements in clinical strategies relevant to bi-frontal pneumocephalus should be considered. TRIAL REGISTRATION: ClinicalTrials.gov (NCT02318199).

Stress Index Can Be Accurately and Reliably Assessed by Visually Inspecting Ventilator Waveforms.

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.).

Use of the critical-care pain observation tool and the bispectral index for the detection of pain in brain-injured patients undergoing mechanical ventilation: A STROBE-compliant observational study.

The assessment of pain in patients with brain injury is challenging due to impaired ability to communicate. We aimed to test the reliability and validity of the critical-care pain observation tool (CPOT) and the bispectral index (BIS) for pain detection in critically brain-injured patients.This prospective observational study was conducted in a neurosurgical intensive care unit in a University-Affiliated Hospital. Adult brain-injured patients undergoing mechanical ventilation were enrolled. Nociceptive (endotracheal suctioning) and non-nociceptive (gentle touching) procedures were performed in a random crossover fashion. Before and immediately after the procedure, CPOT was evaluated by 2 residents and 2 chief nurses, and BIS was documented. The ability to self-report pain was also assessed. The inter-observer reliability of CPOT was analyzed. The criterion and discriminant validities of the CPOT and the BIS were tested.During the study, we enrolled 400 brain-injured patients. The ability to self-report pain was maintained in 214 (54%) and 218 (55%) patients during suctioning and gentle touching, respectively. The intraclass correlation coefficients (95% confidence interval) for inter-observer reliability of CPOT ranged from 0.86 (0.83-0.89) to 0.93 (0.91-0.94). Using self-reported pain as the reference, the area under the receiver operating characteristic curve (95% confidence interval) was 0.84 (0.80-0.88) for CPOT and 0.76 (0.72-0.81) for BIS. When the 2 instruments were combined as either CPOT ≥2 or BIS ≥88 after the procedure, the sensitivity and specificity were 0.90 (0.85-0.93) and 0.59 (0.52-0.66), respectively; and when the 2 instruments were combined as both CPOT ≥2 and BIS ≥88, the sensitivity and specificity were 0.62 (0.55-0.68) and 0.89 (0.83-0.93). Both CPOT and BIS increased significantly after suctioning (all P < .001) but remained unchanged after gentle touching (P ranging from .06 to .14).Our criterion and discriminant validity results supported the use of CPOT and BIS to detect pain in critically brain-injured patients. Combining use of CPOT and BIS in different ways might provide comprehensive pain assessment for different purposes.

Use of esophageal balloon pressure-volume curve analysis to determine esophageal wall elastance and calibrate raw esophageal pressure: a bench experiment and clinical study.

BACKGROUND: 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. METHODS: The Cooper balloon catheter (geometric volume of 2.8 ml) was used in the present study. The balloon was progressively inflated in different gas-tight glass chambers with different inner volumes. Chamber elastance was measured by the fitting of chamber pressure and balloon volume. Balloon pressure-volume (P-V) curves were obtained, and the slope of the intermediate linear section was defined as the estimated chamber elastance. Balloon volume tests were also performed in 40 patients under controlled ventilation. The slope of the intermediate linear section on the end-expiratory esophageal P-V curve was calculated as the Ees. The balloon volume with the largest Pes tidal swing was defined as the best volume. Pressure generated by the esophageal wall during balloon inflation (Pew) was estimated as the product of Ees and best volume. Because the clinical intermediate linear section enclosed filling volume of 0.6 to 1.4 ml in each of the patient, we simplified the estimation of Ees by only using parameters at these two filling volumes. RESULTS: In the bench experiment, bias (lower and upper limits of agreement) was 0.5 (0.2 to 0.8) cmH2O/ml between the estimated and measured chamber elastance. The intermediate linear section on the clinical and bench P-V curves resembled each other. Median (interquartile range) Ees was 3.3 (2.5-4.1) cmH2O/ml. Clinical best volume was 1.0 (0.8-1.2) ml and ranged from 0.6 to 1.4 ml. Estimated Pew at the best volume was 2.8 (2.5-3.5) cmH2O with a maximum value of 5.2 cmH2O. Compared with the conventional method, bias (lower and upper limits of agreement) of Ees estimated by the simple method was - 0.1 (- 0.7 to 0.6) cmH2O/ml. CONCLUSIONS: The slope of the intermediate linear section on the balloon P-V curve correlated with the balloon-surrounding elastance. The estimation of Ees and calibration of Pes were feasible for a small-volume-balloon. TRIAL REGISTRATION: Identifier NCT02976844 . Retrospectively registered on 29 November 2016.

Effect of High-Flow Nasal Cannula Oxygen Therapy Versus Conventional Oxygen Therapy and Noninvasive Ventilation on Reintubation Rate in Adult Patients After Extubation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

PURPOSE: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of high-flow nasal cannula (HFNC) on reintubation in adult patients. PROCEDURES: Ovid Medline, Embase, and Cochrane Database of Systematic Reviews were searched up to November 1, 2016, for RCTs comparing HFNC versus conventional oxygen therapy (COT) or noninvasive ventilation (NIV) in adult patients after extubation. The primary outcome was reintubation rate, and the secondary outcomes included complications, tolerance and comfort, time to reintubation, length of stay, and mortality. Dichotomous outcomes were presented as risk ratio (RR) with 95% confidence intervals (CIs) and continuous outcomes as weighted mean difference and 95% CIs. The random effects model was used for data pooling. FINDINGS: Seven RCTs involving 2781 patients were included in the analysis. The HFNC had a similar reintubation rate compared to either COT (RR, 0.58; 95% CI, 0.21-1.60; P = .29; 5 RCTs, n = 1347) or NIV (RR, 1.11; 95% CI, 0.88-1.40; P = .37; 2 RCTs, n = 1434). In subgroup of critically ill patients, the HFNC group had a significantly lower reintubation rate compared to the COT group (RR, 0.35; 95% CI, 0.19-0.64; P = .0007; 2 RCTs, n = 632; interaction P = .07 compared to postoperative subgroup). Qualitative analysis suggested that HFNC might be associated with less complications and improved patient's tolerance and comfort. The HFNC might not delay reintubation. Trial sequential analysis on the primary outcome showed that required information size was not reached. CONCLUSION: The evidence suggests that COT may still be the first-line therapy in postoperative patients without acute respiratory failure. However, in critically ill patients, HFNC may be a potential alternative respiratory support to COT and NIV, with the latter often associating with patient intolerance and requiring a monitored setting. Because required information size was not reached, further high-quality studies are required to confirm these results.

Use of Cardiac Cycle Locating to Minimize the Influence of Cardiac Artifacts on Esophageal Pressure Measurement During Dynamic Occlusion Test.

BACKGROUND: The dynamic occlusion test is used to guide balloon catheter placement during esophageal pressure (Pes) 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 (Paw) data were collected for off-line analysis. For each occluded inspiratory effort, the change in Pes (ΔPes) was plotted against the change in Paw (ΔPaw), and the slope of the regression line was calculated. The ΔPes/ΔPaw 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 ΔPes/ΔPaw 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 ΔPes/ΔPaw 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 ΔPes versus ΔPaw plot was 0.85 (0.76, 0.91). Bias (lower and upper limit of agreement) of ΔPes/ΔPaw 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.

Optimal esophageal balloon volume for accurate estimation of pleural pressure at end-expiration and end-inspiration: an in vitro bench experiment.

BACKGROUND: Esophageal pressure, used as a surrogate for pleural pressure, is commonly measured by air-filled balloon, and the accuracy of measurement depends on the proper balloon volume. It has been found that larger filling volume is required at higher surrounding pressure. In the present study, we determined the balloon pressure-volume relationship in a bench model simulating the pleural cavity during controlled ventilation. The aim was to confirm whether an optimal balloon volume range existed that could provide accurate measurement at both end-expiration and end-inspiration. METHODS: We investigated three esophageal balloons with different dimensions and materials: Cooper, SmartCath-G, and Microtek catheters. The balloon was introduced into a glass chamber simulating the pleural cavity and volume-controlled ventilation was initiated. The ventilator was set to obtain respective chamber pressures of 5 and 20 cmH2O during end-expiratory and end-inspiratory occlusion. Balloon was progressively inflated, and balloon pressure and chamber pressure were measured. Balloon transmural pressure was defined as the difference between balloon and chamber pressure. The balloon pressure-volume curve was fitted by sigmoid regression, and the minimal and maximal balloon volume accurately reflecting the surrounding pressure was estimated using the lower and upper inflection point of the fitted sigmoid curve. Balloon volumes at end-expiratory and end-inspiratory occlusion were explored, and the balloon volume range that provided accurate measurement at both phases was defined as the optimal filling volume. RESULTS: Sigmoid regression of the balloon pressure-volume curve was justified by the dimensionless variable fitting and residual distribution analysis. All balloon transmural pressures were within ±1.0 cmH2O at the minimal and maximal balloon volumes. The minimal and maximal balloon volumes during end-inspiratory occlusion were significantly larger than those during end-expiratory occlusion, except for the minimal volume in Cooper catheter. Mean (±standard deviation) of optimal filling volume both suitable for end-expiratory and end-inspiratory measurement ranged 0.7 ± 0.0 to 1.7 ± 0.2 ml in Cooper, 1.9 ± 0.2 to 3.6 ± 0.3 ml in SmartCath-G, and 2.2 ± 0.2 to 4.6 ± 0.1 ml in Microtek catheter. CONCLUSIONS: In each of the tested balloon, an optimal filling volume range was found that provided accurate measurement during both end-expiratory and end-inspiratory occlusion.

Association of Social Support and Family Environment with Cognitive Function in Peritoneal Dialysis Patients.

♦ BACKGROUND: Cognitive impairment (CI) is a common phenomenon and predictive of high mortality in peritoneal dialysis (PD) patients. This study aimed to analyze the association of social support and family environment with cognitive function in PD patients. ♦ METHODS: This is a cross-sectional study of PD patients from Peking University First Hospital and the Second Affiliated Hospital of Harbin Medical University. Global cognitive function was measured using the Modified Mini-Mental State Examination (3MS), executive function was measured by the A and B trail-making tests, and other cognitive functions were measured by the Repeatable Battery for the Assessment of Neuropsychological Status. Social support was measured with the Social Support Scale developed by Xiaoshuiyuan and family environment was measured with the Chinese Version of the Family Environment Scale (FES-CV). ♦ RESULTS: The prevalence of CI and executive dysfunction among the 173 patients in the study was, respectively, 16.8% and 26.3%. Logistic regression found that higher global social support (odds ratio [OR] = 1.09, 1.01 - 1.17, p = 0.027) and subjective social support predicted higher prevalence of CI (OR = 1.13, 1.02 - 1.25, p = 0.022), adjusting for covariates. Analyses of the FES-CV dimensions found that greater independence was significantly associated with better immediate memory and delayed memory. Moreover, higher scores on achievement orientation were significantly associated with poorer language skills. ♦ CONCLUSIONS: Our findings indicate that social support is negatively associated with the cognitive function of PD patients and that some dimensions of the family environment are significantly associated with several domains of cognitive function.

Use of the injection test to indicate the oesophageal balloon position in patients without spontaneous breathing: a clinical feasibility study.

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.

The Prophylactic Use of Remifentanil for Delayed Extubation After Elective Intracranial Operations: a Prospective, Randomized, Double-Blinded Trial.

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 extubation 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 µg/kg over 1 minute, followed by a continuous infusion of 0.05 µg/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.