Role of 2-day critical ultrasound training curriculum in guiding clinical activities in China.

BACKGROUND: The effectiveness of critical care ultrasound has been demonstrated and training for it is urgent. Critical Care Ultrasound Study Group (CCUSG) has been dedicated to ultrasound training. The aim of the study was to evaluate course structure and training effect and provide improvement suggestions for future training. METHODS: A multicenter retrospective study was conducted. All participants went through a 2-day training curriculum based on the critical care ultrasonic examination (CCUE) protocol. Pre- and post-class evaluation were applied and data were collected. Non-parametric tests were adopted for the comparison, and a Generalized Linear Model (GLM) was used for further analysis. RESULTS: A total number of 792 trainees, with a mean age of 35.8, participated in the study. There were more males in the study population. Most of the trainees were attendings, and most of them had bachelor's degrees, worked at tertiary hospitals and had a mean working experience of 6.9 years. The scores of all trainees were improved to various degrees after the course. An increase from 50% to 72% (P≤0.001) was seen in theory test scores. All the competency assessment scores, including IAS (34% to 50% for cardiac images and 30% to 60% for pulmonary images), IPS (30% to 50%) and AAS (31% to 44%), were improved. A questionnaire after class suggested that 88.0% of the participants found the training course very useful. CONCLUSION: 2-day training course can improve the ability of physicians to assess critically ill patients with the help of the ultrasound.

Renal hemodynamic evaluation protocol based on the pathophysiological mechanism of acute kidney injury: Critical Care UltraSound Guided-A(KI)BCDE.

The multiple etiological characteristics of acute kidney injury (AKI) have brought great challenges to its clinical diagnosis and treatment. Renal injury in critically ill patients always indicates hemodynamic injury. The Critical Care UltraSound Guided (CCUSG)-A(KI)BCDE protocol developed by the Chinese Critical Ultrasound Study Group (CCUSG), respectively, includes A(KI) diagnosis and risk assessment and uses B-mode ultrasound, Color doppler ultrasound, spectral Doppler ultrasound, and contrast Enhanced ultrasound to obtain the hemodynamic characteristics of the kidney so that the pathophysiological mechanism of the occurrence and progression of AKI can be captured and the prognosis of AKI can be predicted combined with other clinical information; therefore, the corresponding intervention and treatment strategies can be formulated to achieve targeted, protocolized, and individualized therapy.

Self-Appraisal of Clinical Competence in Echocardiography of Chinese Intensivists Post Basic Echocardiography Training.

Objectives To learn the echocardiography skills of intensivists after receiving a basic critical care echocardiography training course, and investigate factors that may influence their performance. Methods We completed a web-based questionnaire that assessed the skills in ultrasound scanning techniques of intensivists who took a training course on basic critical care echocardiography held in 2019 and 2020. Mann-Whitney test was used to analyze the factors which might affect their performance on image acquisition, recognizing clinical syndrome, and measuring the diameter of inferior vena cava, left ventricular ejection fraction and left ventricular outflow tract velocity-time integral.Results We enrolled 554 physicians from 412 intensive care units across China. Among them, 185 (33.4%) reported that they had 10%-30% chance of being misled by critical care echocardiography when making therapeutic decision, and 34 (6.1%) reported that the chance was greater than 30%. Intensivists who performed echocardiography under the guidance of a mentor and finished ultrasound scanning more than 10 times per week reported significant higher scores in image acquisition, clinical syndrome recognition, and quantitative measurement of inferior vena cava diameter, left ventricular ejection fraction and left ventricular outflow tract velocity-time integral than those without mentor and performing echocardiography 10 times or less per week respectively (all P < 0.05).Conclusion The skills in diagnostic medical echocardiography of Chinese intensivists after a basic echocardiographic training course remain low, and further quality assurance training program is clearly warranted.

Evaluation of plasma lactate parameters for predicting mortality of septic patients.

Objective: To compare the accuracy of serum lactate parameters, including lactate peak concentration (LACpeak), lactate time area (LACarea), and lactate clearance (LC) for predicting mortality of the septic patients, and to compare with the predictive accuracy of National Early Warning Score (NEWS) and Sequential Organ Failure Assessment (SOFA) scores. Methods: This study retrospectively screened the septic patients admitted to the ICU in the Medical Information Mart for Intensive Care IV (MIMIC-IV) from 2008 to 2019. The baseline data and outcomes of patients were gathered. The subjects were divided into the non-survival group and the survival group. SOFA, NEWS, LACpeak, and LACarea were recorded. The LC was calculated 6 h after LACpeak. The above parameters were compared by the T-test and Mann-Whitney U test, and odds ratios were calculated adjusting for age and sex. The receiver operating characteristic curves (ROCs) of subjects were plotted according to SOFA, NEWS, LACpeak, and LACarea within 24h, and LC at 6h of ICU admission. The Areas under the ROC curve (AUCs), sensitivity, and specificity were compared with R version 4.1.1. Results: 1,169 septic patients were involved, and 366 (31.3%) patients died within 28 days. Compared to the survival group, the LACpeak of the non-survival group was higher [4.85 (3.2, 7.9) vs. 3.4 (2.6, 5.25) mmol/L, adjusted odds ratio 1.18, P < 0.001], and the LACarea of the non-survivals was higher than the survivals too [18.44 (10.36, 27.63) vs. 13.65 (9.01, 21.73), adjusted odds ratio 1.03, P < 0.001)]. The LC of the survivals at 6 h after LACpeak was significantly higher than that of the non-survivals [0.26 (0.14.0.42) vs. 0.19 (0.10, 0.33), adjusted odds ratio 0.06, P < 0.01]. Within 24h of ICU admission, the AUCs of mortality prediction in descending order were NEWS [0.73 (0.70, 0.76)], SOFA [0.69 (0.66, 0.73)], LACpeak [0.64 (0.61, 0.68)], and LACarea [0.60 (0.56, 0.63)]. There were 204 patients with 6-hour LC after LACpeak the AUCs of LACarea, LACpeak and LC were 0.73(0.65, 0.80), 0.71(0.62,0.78) and 0.65 (0.56, 0.73), respectively. Conclusions: The predictive accuracy of LC was not superior to LACpeak and LACarea for the mortality of the septic patients and the predictive value of all the above lactate parameters for mortality maybe not better than SOFA and NEWS.

Shock Resuscitation - the Necessity and Priority of Renal Blood Perfusion Assessment.

Improving organ perfusion is the aim of shock resuscitation; therefore, improving organ blood perfusion is a direct indicator for shock resuscitation. During shock, different organs have different capacities for blood flow autoregulation. The kidney is an important organ with excellent ability to autoregulate the blood flow and with vulnerability to poor organ perfusion, which places kidney perfusion in a position of necessity and priority relative to that of other organs in shock. Critical-care ultrasonography provides the best evaluation of renal perfusion.

Lung ultrasound score based on the BLUE-plus protocol is associated with the outcomes and oxygenation indices of intensive care unit patients.

PURPOSE: The primary objective was to demonstrate the relationship between lung ultrasound (LUS) manifestations and the outcomes of intensive care unit (ICU) patients. The secondary objective was to determine the characteristics of LUS manifestations in different subgroups of ICU patients. METHODS: This prospective multi-center cohort study was conducted in 17 ICUs. A total of 1702 patients admitted between August 31, 2017 and February 16, 2019 were included. LUS was performed according to the bedside lung ultrasound in emergency (BLUE)-plus protocol, and LUS scores were calculated. Data on the outcomes and oxygenation indices were analyzed and compared between different primary indication groups. RESULTS: The LUS scores were significantly higher for non-survivors than for survivors and were significantly different between the oxygenation index groups, with higher scores in the lower oxygenation index groups. The LUS score was an independent risk factor for the 28-day mortality. The area under the receiver operating characteristic curve was 0.663 for prediction of the 28-day mortality and 0.748 for prediction of an oxygenation index ≤100. CONCLUSIONS: The LUS score based on the BLUE-plus protocol was an independent risk factor for the 28-day mortality and was important for the prediction of an oxygenation index ≤100. An early LUS score within 24 hours of ICU admission helps predicting the outcome of ICU patients.

Effect of Focused Cardiac Ultrasound in Combination with Lung Ultrasound on Critically Ill Patients: A Multicenter Observational Study in China.

Objective Focused cardiac ultrasound (FCU) and lung ultrasound (LU) are increasingly being used in critically ill patients. This study aimed to investigate the effect of FCU in combination with LU on these patients and to determine if the timing of ultrasound examination was associated with treatment change. Methods This is a multicenter cross-sectional observational study. Consecutive patients admitted to the intensive care unit (ICU) were screened for enrollment. FCU and LU were performed within the first 24 h, and treatment change was proposed by the performer based on the ultrasound results and other clinical conditions. Results Among the 992 patients included, 502 were examined within 6 h of ICU admission (early phase group), and 490 were examined after 6 h of admission (later phase group). The early phase group and the later phase group had similar proportions of treatment change (48.8% vs. 49.0%, χ 2=0.003, P=0.956). In the multivariable analysis, admission for respiratory failure was an independent variable associated with treatment change, with an odds ratio (OR) of 2.357 [95% confidence interval (CI): 1.284-4.326, P=0.006]; the timing of examination was not associated with treatment change (OR=0.725, 95%CI: 0.407-1.291, P=0.275). Conclusions FCU in combination with LU, whether performed during the early phase or later phase, had a significant impact on the treatment of critically ill patients. Patients with respiratory failure were more likely to experience treatment change after the ultrasound examination.

Hemodynamics in Shock Patients Assessed by Critical Care Ultrasound and Its Relationship to Outcome: A Prospective Study.

BACKGROUND: Shock is one of the causes of mortality in the intensive care unit (ICU). Traditionally, hemodynamics related to shock have been monitored by broad-spectrum devices with treatment guided by many inaccurate variables to describe the pathophysiological changes. Critical care ultrasound (CCUS) has been widely advocated as a preferred tool to monitor shock patients. The purpose of this study was to analyze and broaden current knowledge of the characteristics of ultrasonic hemodynamic pattern and investigate their relationship to outcome. METHODS: This prospective study of shock patients in CCUS was conducted in 181 adult patients between April 2016 and June 2017 in the Department of Intensive Care Unit of West China Hospital. CCUS was performed within the initial 6 hours after shock patients were enrolled. The demographic and clinical characteristics, ultrasonic pattern of hemodynamics, and outcome were recorded. A stepwise bivariate logistic regression model was established to identify the correlation between ultrasonic variables and the 28-day mortality. RESULTS: A total of 181 patients with shock were included in our study (male/female: 113/68). The mean age was 58.2 ± 18.0 years; the mean Acute Physiology and Chronic Health Evaluation II (APACHE II score) was 23.7 ± 8.7, and the 28-day mortality was 44.8% (81/181). The details of ultrasonic pattern were well represented, and the multivariate analysis revealed that mitral annular plane systolic excursion (MAPSE), mitral annular peak systolic velocity (S'-MV), tricuspid annular plane systolic excursion (TAPSE), and lung ultrasound score (LUSS) were the independent risk factors for 28-day mortality in our study, as well as APACHE II score, PaO2/FiO2, and lactate (p = 0.047, 0.041, 0.022, 0.002, 0.027, 0.028, and 0.01, respectively). CONCLUSIONS: CCUS exam on admission provided valuable information to describe the pathophysiological changes of shock patients and the mechanism of shock. Several critical variables obtained by CCUS were related to outcome, hence deserving more attention in clinical decision-making. Trial Registration. The study was approved by the Ethics Committee of West China Hospital Review Board for human research with the following reference number 201736 and was registered on ClinicalTrials. This trial is registered with NCT03082326 on 3 March 2017 (retrospectively registered).

Physicians' abilities to obtain and interpret focused cardiac ultrasound images from critically ill patients after a 2-day training course.

BACKGROUND: This study aimed to determine whether a focused 2-day cardiac ultrasound training course could enable physicians to obtain and interpret focused cardiac ultrasound (FCU) images from critically ill patients. METHODS: We retrospectively reviewed the FCU images submitted by the physicians who attended a 2-day FCU training courses. Three experienced trainers reviewed the images separately. They determined whether the images were assessable and scored the images on an 8-point scale. They also decided whether the physicians provided correct responses for visual estimations of the left ventricular ejection fraction (LVEF) and right ventricle (RV) dilatation and septal motion. RESULTS: Among the 327 physicians, 291 obtained images that were considered assessable (89%). The scores for parasternal short-axis view were lower than those obtained for other transthoracic echocardiographic views, p < 0.001. More physicians provided incorrect appraisals of LVEF than of RV dilatation and septal motion (19.9% vs. 3.1%, p < 0.001). The percentages of incorrect answers by LVEF category were as follows: 34.8% on images of LVEF < 30, 24.7% on images of LVEF 30-54, and 16.4% on images of LVEF ≥55%, p < 0.001. A logistic regression analysis showed that patients with abnormal LVEF were associated with physicians' incorrect assessment of LVEF, with an odds ratio of 1.923 (95% confidence interval (CI):1.071-3.456, p = 0.029). CONCLUSIONS: A large proportion of physicians could obtain and interpret FCU images from critically ill patients after a 2-day training course. However, they still scored low on the parasternal short-axis view and were more likely to make an incorrect assessment of LVEF in patients with abnormal left ventricular systolic function.

Pulmonary edema following diuretic therapy: A case report.

INTRODUCTION: Diuretics are a commonly used for the treatment of acute pulmonary edema. However, inappropriate administration of diuretic drugs can result in clinical treatment failure and cause acute pulmonary edema. This is due to rapid decreases in intravascular volume as a result of diuretic treatment. To date, the clinical phenomenon of inappropriate use of diuretics leading to acute pulmonary edema remains unexplored and unrecognized. Here, we report the first case of this problem-pulmonary edema following diuretic therapy. PATIENT CONCERNS: A 71-year-old male patient who was intubated and transferred to the intensive care unit (ICU) due to respiratory failure was initially diagnosed with pneumonia as a complication of acute respiratory distress syndrome (ARDS). After treatments including antibiotics, lung protective ventilation strategies, and restrictive fluid management, his respiratory symptoms improved. However, the patient's dyspnea became more severe after experimental diuretic therapy. DIAGNOSIS: A point-of-care ultrasound (POCUS) examination showed increased extravascular lung water retention during a hypovolemic state. After full examinations and analysis, the diagnosis of acute pulmonary edema was determined. INTERVENTIONS: The most likely cause of acute pulmonary edema was left ventricular (LV) hyperdynamic status due to a hypovolemic status caused by excessive diuretic therapy. Consequently, we administrated intravenous fluids and a ß-receptor blocker to the patient. OUTCOMES: Following these treatment, the patient's respiratory distress improved remarkably. CONCLUSION: We report the first case of pulmonary edema following diuretic therapy to stress the need of physicians to follow guidelines of clinical practice. Maintaining an appropriate volume status and treatment of ß-receptor blockers is the key to reversing the progress of this adverse effect. In this process, POCUS is a reliable diagnostic tool to identify the cause of acute pulmonary edema and can increase the accuracy of clinical evaluations. It is likely that a wider use of POCUS will help physicians to obtain a faster, and more accurate, diagnosis of the etiology of acute pulmonary edema, thus allowing a more appropriate therapy.

[Correlation Between the Severity of Lung Ultrasound Score in Non-gravity Dependent Areas and Poor Prognosis of Patients with Shock and on Mechanical Ventilation].

OBJECTIVE: To explore whether ultrasound abnormalities in the non-gravity dependent areas (area 1-2) of the lungs are associated with poor prognosis in patients with shock and on mechanical ventilation. METHODS: We retrospectively analyzed the data of lung ultrasound from 181 patients with shock from Apr. 2016 to Nov. 2017. The patients were divided into the survival group and the non-survival group according to the 28 d outcome. Single factor and multivariate Cox regression were used to analyze the relationship between lung ultrasound score of the overall and each area and the 28 d mortality.Kaplan-Meier curve was used to analyze the relationship between the severity of ultrasound lesions in area 1-2 and the prognosis at 28 d. RESULTS: 169 patients were included.There were 106 males (62.7%) and 63 females (37.3%).There were 90 patients in the survivel group and 79 patients in the non-survival group.Single factor Cox regression analysis found that adjusting the age, acute physiology and chronic health evaluation (APACHE) Ⅱ score, lactate level, urine output per hour, application of vasoactive agent, oxygenation index, lungs ultrasound score of area 1-6, area 1-2 and area 3-4 were associated with 28 d mortality. Multivariate Cox regression revealed that lung ultrasound score of area 1-2 was the independent risk factor of 28 d mortality, as well as APACHE Ⅱ score and lactate level. The Kaplan-Meier curve found that the more severe the lesion in area 1-2, the lower the survival rate at 28 d. CONCLUSION: Lung ultrasound score of area 1-2 in patients with shock and on mechanical ventilation may be a predictor of poor prognosis at 28 d.

Physicians' Ability to Visually Estimate Left Ventricular Ejection Fraction, Right Ventricular Enlargement, and Paradoxical Septal Motion After a 2-Day Focused Cardiac Ultrasound Training Course.

OBJECTIVE: Focused cardiac ultrasound (FCU) can provide useful information for the management of shock and acute respiratory distress syndrome. This study aimed to determine whether a 2-day focused cardiac ultrasound training course could enable critical care physicians to interpret ultrasound images in terms of left ventricular ejection fraction (LVEF), ratio of right ventricular end-diastolic area to left ventricular end-diastolic area (R/LVEDA), and septal kinetics. DESIGN: A prospective analysis of an image test score. SETTING: Ultrasound training programs in 7 regions across China. PARTICIPANTS: Two hundred forty-seven critical care physicians. INTERVENTIONS: All participants received a 2-day FCU training, including 4 sessions of basic heart function appraisal, 3 sessions of hands-on practice, and 1 session of image interpretation. MEASUREMENTS AND MAIN RESULTS: The post-training total scores were considerably higher than those of pretraining (75.6% v 58.9%, respectively, p < 0.001). After the course, the trainees obtained considerably higher scores on images with LVEF <30% than on images with LVEF 30% to 54% and LVEF ≥55% (100% v 60.0% and 60.0%, respectively, p < 0.001). The trainees obtained considerably higher scores on images with R/LVEDA >1 than on images with R/LVEDA 0.6 to 1 and R/LVEDA <0.6 (90.0% v 80.0% and 80.0%, p = 0.042 and p < 0.001, respectively). The trainees obtained considerably higher scores on images with paradoxical septal movement (PSM) than on images without PSM (100% v 75.0%, respectively, p < 0.001). CONCLUSION: The physicians' abilities to assess LVEF, RV enlargement, and PSM improved after the training course, and they demonstrated more accurate estimations of the most obviously abnormal images.

Diagnostic value of cardiopulmonary ultrasound in elderly patients with acute respiratory distress syndrome.

BACKGROUND: Lung ultrasound and echocardiography are mainly applied in critical care and emergency medicine. However, the diagnostic value of cardiopulmonary ultrasound in elderly patients with acute respiratory distress syndrome (ARDS) is still unclear. METHODS: Consecutive patients admitted to ICU with the diagnosis of suspected ARDS based on clinical grounds were enrolled. Cardiopulmonary ultrasound was performed as part of monitoring on day 1, day 2 and day 3. On each day a bedside ultrasound was performed to examine the lungs and calculate the Left Ventricular Ejection Fraction (LVEF). On day 3, a thoracic CT was performed on each patient as gold standard for ARDS imaging diagnosis. According to the results from CT scan, patients were grouped into ARDS group or Non-ARDS group. The relation between the cardiopulmonary ultrasound results on each day and the results of CT scan was analyzed. RESULTS: Fifty one consecutive patients aged from 73 to 97 years old were enrolled. Based on CT criteria, 33 patients were classified into the ARDS group, while 18 patients were included in non-ARDS group. There was no significant difference between the two groups in baseline characteristics, including gender, age, underlying disease, comorbidities, APACHE II score, SOFA score, and PaO2/FiO2 ratio (P > 0.05). Lung ultrasound (LUS) examination results were consistent with the CT scan results in diagnosis of pulmonary lesions. The Kappa values were 0.55, 0.74 and 0.82 on day 1, day 2 and day 3, respectively. The ROC analysis showed that the sensitivity, specificity and area under curve of ROC (AUROC) for lung ultrasound in diagnose ARDS were 0.788,0.778,0.783;0.909,0.833,0.871;0.970,0.833,0.902 on day 1, day 2 and day 3, respectively. However, cardiopulmonary ultrasound performed better in diagnosing ARDS in elderly patients. The sensitivity, specificity and AUROC were 0.879,0.889,0.924;0.939,0.889,0.961;and 0.970,0.833,0.956 on day 1, day 2 and day 3, respectively. The combined performances of cardiopulmonary ultrasound, N-terminal pro-brain natriuretic peptide (NT-proBNP), and PaO2/FiO2 ratio improved the specificity of the diagnosis of ARDS in elderly patients. CONCLUSIONS: LUS examination results were consistent with the CT scan results in diagnosis of pulmonary lesions. Cardiopulmonary ultrasound has a greater diagnostic accuracy in elderly patients with ARDS, compared with LUS alone. The combined performances of cardiopulmonary ultrasound, NT-proBNP, and PaO2/FiO2 increased the specificity of the diagnosis of ARDS in elderly patients.

The PIEPEAR Workflow: A Critical Care Ultrasound Based 7-Step Approach as a Standard Procedure to Manage Patients with Acute Cardiorespiratory Compromise, with Two Example Cases Presented.

Critical care ultrasound (CCUS) has been widely used as a useful tool to assist clinical judgement. The utilization should be integrated into clinical scenario and interact with other tests. No publication has reported this. We present a CCUS based "7-step approach" workflow-the PIEPEAR Workflow-which we had summarized and integrated our experience in CCUS and clinical practice into, and then we present two cases which we have applied the workflow into as examples. Step one is "problems emerged?" classifying the signs of the deterioration into two aspects: acute circulatory compromise and acute respiratory compromise. Step two is "information clear?" quickly summarizing the patient's medical history by three aspects. Step three is "focused exam launched": (1) focused exam of the heart by five views: the assessment includes (1) fast and global assessment of the heart (heart glance) to identify cases that need immediate life-saving intervention and (2) assessing the inferior vena cava, right heart, diastolic and systolic function of left heart, and systematic vascular resistance to clarify the hemodynamics. (2) Lung ultrasound exam is performed to clarify the predominant pattern of the lung. Step four is "pathophysiologic changes reported." The results of the focused ultrasound exam were integrated to conclude the pathophysiologic changes. Step five is "etiology explored" diagnosing the etiology by integrating Step two and Step four and searching for the source of infection, according to the clues extracted from the focused ultrasound exam; additional ultrasound exams or other tests should be applied if needed. Step six is "action" supporting the circulation and respiration sticking to Step four. Treat the etiologies according step five. Step seven is "recheck to adjust." Repeat focused ultrasound and other tests to assess the response to treatment, adjust the treatment if needed, and confirm or correct the final diagnosis. With two cases as examples presented, we insist that applying CCUS with 7-step approach workflow is easy to follow and has theoretical advantages. The coming research on its value is expected.

Preliminary Exploration of Epidemiologic and Hemodynamic Characteristics of Restrictive Filling Diastolic Dysfunction Based on Echocardiography in Critically Ill Patients: A Retrospective Study.

OBJECTIVE: To preliminarily describe the epidemiologic and hemodynamic characteristics of critically ill patients with restrictive filling diastolic dysfunction based on echocardiography. SETTING: A retrospective study. METHODS: Epidemiologic characteristics of patients with restrictive filling diastolic dysfunction in ICU were described; clinical and hemodynamic data were preliminarily summarized and compared between patients with and without restrictive filling diastolic dysfunction; most of the data were based on echocardiography. RESULTS: More than half of the patients in ICU had diastolic dysfunction and about 16% of them had restrictive filling pattern. The patients who had restrictive filling diastolic dysfunction were more likely to have wider diameter of IVC (2.18 ± 0.50 versus 1.92 ± 0.43, P = 0.037), higher extravascular lung water score (15.9 ± 9.2 versus 13.2 ± 9.1, P = 0.014), lower left ventricular ejection fraction (EF-S: 53.0 ± 16.3 versus 59.3 ± 12.5, P = 0.014), and lower percentage of normal LAP that was estimated by E/e' (8.9% versus 90.0%, P = 0.001) when compared with those of patients without restrictive filling diastolic dysfunction. CONCLUSION: Our results suggest that critically ill patients with restrictive filling diastolic dysfunction may experience rising volume status, increasing extravascular lung water ultrasonic score, reducing long-axis systolic dysfunction, and less possibility of normal left atrial pressure. Intensivists are advised to pay more attention to patients with diastolic dysfunction, especially the exquisite fluid management of patients with restrictive filling pattern due to the close relationship of restrictive filling diastolic dysfunction with volume status and extravascular lung water in our study.

Relationship between inferior vena cava diameter ratio and central venous pressure.

PURPOSE: To explore the relationship between the shape of the inferior vena cava (IVC) lumen and central venous pressure (CVP). METHODS: In 60 patients undergoing mechanical ventilation and CVP monitoring in the Intensive Care Unit of Peking Union Medical College Hospital from July to October 2016, we measured with B-mode ultrasonography the transverse maximum (MXD) and minimum diameter (MID) of the IVC at end expiration, and calculated the diameter ratio (DR) as MXD/MID. Patients were divided into three groups according to CVP: low (CVP < 8 mm Hg), intermediate (8 mm Hg ≤ CVP ≤ 10 mm Hg), and high (CVP > 10 mm Hg). RESULTS: MXD was 2.32 ± 0.41 cm, MID was 1.41 ± 0.40 cm, and DR was 1.76 ± 0.49. CVP was 9.27 ± 2.99 mm Hg. DR correlated with CVP (r = -0.527, P < .001). The low-CVP group had greater dispersion of DR values, with a large variety in IVC shape (elliptical, irregular, teardrop-shaped, partially collapsed…). The area under the ROC curve for predicting CVP with DR, with a CVP threshold of 8 mm Hg was 0.835 (95% CI, 0.726-0.945; P < .05). With a DR cutoff value of 1.76, sensitivity was 0.765 and specificity was 0.781. CONCLUSIONS: DR above 1.7 is predictive of CVP < 8 mm Hg.

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model.

This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H2O. The PEEP was reduced by 2 cm H2O every 10 min until 0 cm H2O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO2, and calculated from arterial CO2 partial pressure (PaCO2) and mixed expired CO2 (PeCO2) using the following formula: VD/VT = (PaCO2 - PeCO2)/PaCO2. The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H2O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H2O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.

[A comparative study of different bedside lung ultrasound examination for the location and signs of diaphragmatic points].

OBJECTIVE: To investigate the differences of the locations and signs of the phrenic points between the Modified Bedside Lung Ultrasound Examination (M-BLUE) and Bedside Lung Ultrasound Examination (BLUE). METHODS: A total of 61 consecutive patients who were treated in the Department of Critical Care Medicine at Peking Union Medical College Hospital in January and February of 2015 were enrolled in this study. BLUE and M-BLUE were both performed on each patient. The differences of examination results were compared. RESULTS: (1) There were 47.5% (58/122) different locations of the phrenic points and 18.0% (22/122) different echo-signs between the BLUE protocol and the M-BLUE protocol. (2) Compared with BLUE protocol, changes of locations [67.9% (19/28) vs 33.3% (11/33)] and signs [42.9% (12/28) vs 12.1% (4/33)] of the phrenic points in the M-BLUE protocol in patients with respiratory failure were significantly higher than those without pulmonary diseases. Among 5 patients with acute respiratory distress syndrome and 6 patients with chronic obstructive pulmonary disease, all presented changes in locations of the phrenic point in the M-BLUE protocol, while 3 and 4 showed changes in signs respectively. (3) Signs of the phrenic point in the M-BLUE protocol were more consistent with the result of the chest CT than those in the BLUE protocol. CONCLUSION: Compared with BLUE protocol, M-BLUE protocol seems more accurate in locating the phrenic point and more specific for the diagnosis of pulmonary disease. Compared with BLUE protocol, M-BLUE is more valuable for critical patients.

A novel insight in exploring the positive end expiratory pressure for sustained ventilation after lung recruitment in a porcine model of acute respiratory distress syndrome.

The aim of the present study was to explore a novel insight to determine the positive end expiratory pressure (PEEP) for sustained ventilation after lung recruitment in an acute respiratory distress syndrome (ARDS) model. Continuous infusion of oleic acid was performed to establish a ARDS model. Pressure control ventilation (PCV) was applied for lung recruitment with PEEP of 20 cm H2O. After lung recruitment, maneuver was changed to volume-controlled ventilation and PEEP titration were performed by decreasing PEEP gradually starting from the level of 20 cm H2O. The optimal level of PEEP for sustained ventilation was set as the lowest PEEP until oxygen partial pressure (PaO2) plus carbon dioxide partial pressure (PaCO2) ≥400 mmHg. Hemodynamic and respiratory parameters at basal level, ARDS state and different levels of PEEP around the optimal PEEP were recorded. The defined optimal PEEP was 13.14 ± 1.35 cm H2O. Respiratory parameters including intrapulmonary shunt (Qs/Qt) and arterial oxygen saturation (SaO2) were significantly improved by various levels of PEEP for sustained ventilation after lung recruitment (P<0.05). Static compliance (Cst) and dynamic compliance (Cdyn) were also significantly increased after application of different levels of PEEP ventilation after lung recruitment (P<0.05). There was no significant statistic difference on most hemodynamic parameters (P>0.05) between various levels of PEEP. The application of different PEEP levels around the defined optimal PEEP had an obvious improvement on respiratory mechanics and gas exchange for collapsed lung tissue without influencing the hemodynamics.