B-lines score on lung ultrasound as a direct measure of respiratory dysfunction in ICU patients with acute kidney injury

Proceedings of the 2022 UAB CRRT Academy: Non-Invasive Hemodynamic Monitoring to Guide Fluid Removal with CRRT and Proliferation of Extracorporeal Blood Purification Devices

In 2022, we celebrated the 15th anniversary of the University of Alabama at Birmingham (UAB) Continuous Renal Replacement Therapy (CRRT) Academy, a 2-day conference attended yearly by an international audience of over 100 nephrology, critical care, and multidisciplinary trainees and practitioners. This year, we introduce the proceedings of the UAB CRRT Academy, a yearly review of select emerging topics in the field of critical care nephrology that feature prominently in the conference. First, we review the rapidly evolving field of non-invasive hemodynamic monitoring and its potential to guide fluid removal by renal replacement therapy (RRT). We begin by summarizing the accumulating data associating fluid overload with harm in critical illness and the potential for harm from end-organ hypoperfusion caused by excessive fluid removal with RRT, underscoring the importance of accurate, dynamic assessment of volume status. We describe four applications of point-of-care ultrasound used to identify patients in need of urgent fluid removal or likely to tolerate fluid removal: lung ultrasound, inferior vena cava ultrasound, venous excess ultrasonography, and Doppler of the left ventricular outflow track to estimate stroke volume. We briefly introduce other minimally invasive hemodynamic monitoring technologies before concluding that additional prospective data are urgently needed to adapt these technologies to the specific task of fluid removal by RRT and to learn how best to integrate them into practical fluid-management strategies. Second, we focus on the growth of novel extracorporeal blood purification devices, starting with brief reviews of the inflammatory underpinnings of multiorgan dysfunction and the specific applications of pathogen, endotoxin, and/or cytokine removal and immunomodulation. Finally, we review a series of specific adsorptive technologies, several of which have seen substantial clinical use during the COVID-19 pandemic, describing their mechanisms of target removal, the limited existing data supporting their efficacy, ongoing and future studies, and the need for additional prospective trials.

Prognostic value of the early lung ultrasound B-line score for postoperative pulmonary insufficiency in patients undergoing thoracic surgery: an observational study

BACKGROUND

Postoperative pulmonary insufficiency (PPI) is an important contributor to morbidity and mortality after thoracic surgery. Lung ultrasound is a reliable tool for assessing respiratory function. We sought to determine the clinical value of the early lung ultrasound B-line score for predicting changes in pulmonary function after thoracic surgery.

METHODS

Eighty-nine patients undergoing elective lung surgery were included in this study. The B-line score was determined 30 min after removal of the endotracheal tube, and the PaO2/FiO2 ratio was recorded 30 min after extubation and on the third postoperative day. Patients were divided into normal (PaO2/FiO2 ≥ 300) and PPI (PaO2/FiO2 < 300) groups according to their PaO2/FiO2 ratios. A multivariate logistic regression model was used to identify independent predictors of postoperative pulmonary insufficiency. Receiver operating characteristic (ROC) analysis was performed for significantly correlated variables.

RESULTS

Eighty-nine patients undergoing elective lung surgery were included in this study. We evaluated 69 patients in the normal group and 20 in the PPI group. Patients conforming to NYHA class 3 at administration were significantly more represented in the PPI group (5.8 and 55%; p < 0.001). B-line scores were significantly higher in the PPI group than in the normal group (16; IQR 13-21 vs. 7; IQR 5-10; p < 0.001). The B-line score was an independent risk factor (OR = 1.349 95% CI 1.154-1.578; p < 0.001), and its best cutoff value for predicting PPI was 12 (sensitivity: 77.5%; specificity: 66.7%).

CONCLUSIONS

Lung ultrasound B-line scores 30 min after extubation are effective in predicting early PPI in patients undergoing thoracic surgery. Trial registration This study was registered with the Chinese Clinical Trials Registry (ChiCTR2000040374).

Fluid management in acute kidney injury: from evaluating fluid responsiveness towards assessment of fluid tolerance

Despite the widespread use of intravenous fluids in acute kidney injury (AKI), solid evidence is lacking. Intravenous fluids mainly improve AKI due to true hypovolaemia, which is difficult to discern at the bedside unless it is very pronounced. Empiric fluid resuscitation triggered only by elevated serum creatinine levels or oliguria is frequently misguided, especially in the presence of fluid intolerance syndromes such as increased extravascular lung water, capillary leak, intra-abdominal hypertension, and systemic venous congestion. While fluid responsiveness tests clearly identify patients who will not benefit from fluid administration (i.e. those without an increase in cardiac output), the presence of fluid responsiveness does not guarantee that fluid therapy is indicated or even safe. This review calls for more attention to the concept of fluid tolerance, incorporating it into a practical algorithm with systematic venous Doppler ultrasonography assessment to use at the bedside, thereby lowering the risk of detrimental kidney congestion in AKI.

Point-of-care ultrasound in pediatric nephrology

Point-of-care ultrasound (POCUS) has evolved in recent years in clinical practice, helping in early bedside diagnosis of important etiologies. Many medical schools and training programs are integrating POCUS into their curriculum. Especially with the technological advances of newer handheld ultrasound devices, POCUS has now become a component adjunct to clinical examination, in the clinic and bedside in critical care units. The diagnostic utility of POCUS lies both in early identification of critical kidney disease, and also extra-renal pathologies from a focused cardiac ultrasound, lung ultrasound, and integrated fluid assessment. There is a need to incorporate POCUS in training in pediatric nephrology and establish competency standard criteria. This review shall cover how POCUS helps in enhancing patient care in pediatric kidney disorders and critical children, and the recent advances.

Protective Effect of Nalbuphine Combined With Dexmedetomidine on the Lungs of Children With Atelectasis and Foreign Body in the Bronchus During the Perioperative Period

Objective: The present study aims to explore the protective effect of nalbuphine combined with dexmedetomidine on the lungs of children with atelectasis who have a foreign body in a bronchus during the perioperative period.

Methods: A total of 180 patients whose computed tomography scan showed atelectasis and a foreign body in a bronchus were randomly divided into three groups: group C (conventional anesthesia group), group D (dexmedetomidine group), and group N + D (nalbuphine combined with the dexmedetomidine group). The following indicators were recorded: 1) heart rate (HR) and mean arterial pressure (MAP) prior to induction (T0), at bronchoscope placement (T1), at intubation after surgery (T2), at tube removal (T3), 10 min after tube removal (T4), 20 min after tube removal (T5), and at awaking (T6); 2) monocyte toll-like receptors (TLRs) TLR⁃2, TLR⁃4, tumor necrosis factor α, interleukin 6, oxygenation index, and the B-line sum at T0, T3, 2 h (T7), and 24 h (T8) after tube removal; and 3) hospital stay after surgery.

Results: Compared with group C, in group D and group N + D, 1) the HR and MAP at T1∼T6 were lower; 2) the inflammatory factor indicator and B-line sum were lower, and the oxygenation index was higher at T7 and T8; 3) the agitation and cough scores were decreased during tube removal; and 4) the Ramsay sedation score was higher, and ventilator weaning time was shortened at T4∼T6 (p &lt; 0.05). Compared with group D, in group N + D, 1) the inflammatory factor indicator and B-line sum were lower at T8; 2) the oxygenation index was higher (p &lt; 0.05). Compared with groups C and D, in group N + D, the length of hospital stay was decreased (p &lt; 0.05).

Conclusion: In patients with atelectasis and a foreign body in a bronchus during the perioperative period, nalbuphine combined with dexmedetomidine may be capable of reducing the oxidative stress response, improving the oxygenation index, decreasing the pulmonary fluid content, protecting the lung, and facilitating postoperative recovery.

Lung Congestion Severity in Kidney Transplant Recipients Is Not Affected by Arteriovenous Fistula Function

Lung ultrasound is a bedside technique for the assessment of pulmonary congestion. The study aims to assess the severity of lung congestion in kidney transplant recipients (KTR) in relation to arteriovenous fistula (AVF) patency. One hundred fifty-seven patients at least 12 months after kidney transplantation were recruited to participate in a cross-sectional study. Apart from routine visits, lung ultrasound at 28 typical points was performed. The patients were assigned to either AVF+ or AVF− groups. The mean number of lung ultrasound B-lines (USBLs) was 5.14 ± 4.96 with no differences between groups: 5.5 ± 5.0 in AVF+ and 4.8 ± 4.9 in AVF−, p = 0.35. The number and proportion of patients with no congestion (0–5 USBLs), mild congestion (6–15 USBLs), and moderate congestion (16–30 USBLs) were as follows: 101 (64.7%), 49 (31.4%), and 6 (3.8%), respectively. In multivariate analysis, only symptoms (OR 5.90; CI 2.43,14.3; p = 0.0001), body mass index (BMI) (OR 1.09; CI 1.03,1.17; p = 0.0046), and serum cholesterol level (OR 0.994; CI 0.998,1.000; p = 0.0452) contributed significantly to the severity of lung congestion. Lung ultrasound is a valuable tool for the evaluation of KTR. Functioning AVF in KTR is not the major factor affecting the severity of pulmonary congestion.

Lung Ultrasound in COVID-19: Clinical Correlates and Comparison with Chest Computed Tomography

Lung ultrasound (LUS) and chest computed tomography (chest CT) are largely employed to evaluate coronavirus disease 2019 (COVID-19) pneumonia. We investigated semi-quantitative LUS and CT scoring in hospitalized COVID-19 patients. LUS and chest CT were performed within 24 h upon admission. Both were analyzed according to semi-quantitative scoring systems. Subgroups were identified according to median LUS score. Patients within higher LUS score group were older (79 vs 60 years, p<0.001), had higher C-reactive protein (CRP) (7.2 mg/dl vs 1.3 mg/dl, p<0.001) and chest CT score (10 vs 4, p=0.027) as well as lower PaO2/FiO2 (286 vs 356, p=0.029) as compared to patients within lower scores. We found a significant correlation between scores (r=0.390, p=0.023). Both LUS and CT scores correlated directly with patients age (r=0.586, p<0.001 and r=0.399, p=0.021 respectively) and CRP (r=0.472, p=0.002 and r=0.518, p=0.002 respectively), inversely with PaO2/FiO2 (r=-0.485, p=0.003 and r=-0.440, p=0.017 respectively). LUS score only showed significant correlation with hs-troponin T, NT-pro-BNP, and creatinine (r=0.433, p=0.019; r=0.411, p=0.027, and r=0.497, p=0.001, respectively). Semi-quantitative bedside LUS is related to the severity of COVID-19 pneumonia similarly to chest CT. Correlation of LUS score with markers of cardiac and renal injury suggests that LUS might contribute to a more comprehensive evaluation of this heterogeneous population.

Lung Ultrasound: A "Biomarker" for Fluid Overload?

Fluid overload is associated with poor outcomes in patients with acute kidney injury as well as end-stage kidney disease. Lung ultrasound (LUS) has been used in many different settings and specialties including the emergency department, intensive care unit, trauma, cardiology, and nephrology. Although LUS has been a valuable tool in assessing pulmonary congestion, LUS findings may not always be pathognomonic for pulmonary congestion. Furthermore, the feasibility of doing an extensive LUS examination as has been done in research studies may be hard to implement within the clinical setting. This review will go over the use of LUS to evaluate for fluid overload, compare LUS with other markers of fluid overload, review limitations of LUS, and suggest potential future directions in the use of LUS in nephrology.

Extravascular Lung Water and Effect on Oxygenation Assessed by Lung Ultrasound in Adult Cardiac Surgery

Introduction

The extravascular lung water content is determined by the use of lung ultrasound (LUS) which is represented as B-lines. The aim of this study was to investigate whether the LUS measurement of extravascular lung water was correlated to changes in oxygenation.

Methods

This prospective cohort study was comprised of 73 patients with an average age of 56 (range: 18 to 87 years) who underwent elective cardiac surgery using cardiopulmonary bypass. The LUS score was performed preoperatively, time zero (T0), at one hour (T1), and at 24 hours (T2) post-surgery. Additionally, arterial oxygen partial pressure and fraction of inspired oxygen (PaO₂/FiO₂) ratio were measured at each time and the time-to-extubation.

Results

A negative correlation was found between the LUS score and PaO₂/FiO₂ at T1 (p < 0.004). Extubation time and changes in the lung ultrasound score at T0 - T2 were positively correlated (p < 0.03). Plus, there was a positive correlation between fluid balance and lung ultrasound score at T2 (p < 0.03).

Conclusion

We found three significant correlations that support the use of LUS in cardiac surgery: 1) the more B-lines, the lower the oxygenation; 2) the more B-lines, the longer the period of ventilation; 3) the more B-lines, the more positive the fluid balance. LUS is a non-invasive bedside investigation that can be used to judge extravascular lung water, providing useful information in the management of patient oxygenation, fluid balance, and extubation.

Using lung ultrasound to quantitatively evaluate pulmonary water content

BACKGROUND

Increases in extravascular lung water (EVLW) can lead to respiratory failure. This study aimed to investigate whether the B-line score (BLS) was correlated with the EVLW content determined by the lung wet/dry ratio in a rabbit model.

METHODS

A total of 45 New Zealand rabbits were randomly assigned to nine groups. Among the animals, models of various lung water content levels were induced by the infusion of different volumes of warm sterile normal saline (NS) via the endotracheal tube. The arterial blood gas, spontaneous respiratory rate, and PaO₂ /FiO₂ ratio were detected before and after infusion. In addition, the B-lines were determined before and immediately after infusion in each group. Finally, both lungs were resected to determine the wet/dry ratio. In addition, all lung specimens were analyzed histologically, and EVLW was quantified using the BLS based on the number and confluence of B-lines in the intercostal space.

RESULTS

The BLS increased with increasing infusion volume. The BLS was statistically correlated with the wet/dry ratio (r² = .946) and with the PaO₂ /FiO₂ ratio (r² = .916). Furthermore, a repeatability study was performed for the lung ultrasound (LUS) technology (Bland-Altman plots), and the results suggest that LUS had favorable intraobserver and interobserver reproducibility.

CONCLUSIONS

This study is the first to suggest that the BLS can serve as a sensitive, quantitative, noninvasive, and real-time indicator of EVLW in a rabbit model of lung water accumulation. Notably, the BLS displayed an obvious correlation with the experimental gravimetry results and could also be used to predict the pulmonary oxygenation status.

Assessing Extravascular Lung Water With Ultrasound: A Tool to Individualize Fluid Management?

Aggressive fluid resuscitation has become standard of care for hypotensive patients with sepsis. However, sepsis is a syndrome that occurs in patients with diverse underlying physiology and a one-size-fits-all approach to fluid administration seems misguided. To individualize fluid management, several methods to assess fluid responsiveness have been validated, but even in fluid responsive patients, fluid administration may still be harmful and lead to pulmonary edema. Hence, to individualize fluid management, in addition to fluid responsiveness, fluid tolerance needs to be assessed. This article examines whether lung ultrasound can be useful to detect excess extravascular lung water (EVLW) and thus assess fluid tolerance. The physiology of EVLW and the principles of lung ultrasound are briefly described. Articles examining the correlation between EVLW and lung ultrasound findings in various clinical settings are carefully reviewed. Overall, lung ultrasound has been found to be an excellent tool to detect EVLW, but large outcome studies investigating lung ultrasound-guided fluid management are still lacking.

Lung Ultrasound Guided Fluid Management Protocol for the Critically Ill Patient: study protocol for a multi-centre randomized controlled trial

Background

In routine intensive care unit (ICU) practice, fluids are often administered without a safety limit, which may lead to fluid overload and decreased survival. Recently, B-lines score (BLS) has been validated as a lung ultrasound (LUS) quantification of pulmonary congestion. This suggests that LUS may provide a safety threshold to conduct fluid therapy and to avoid overhydration. However, there is no randomized study to test the utility of LUS in guiding fluid management in ICU patients by using a pre-specified BLS cut-off value as a threshold for fluid removal.

Methods

LUS Guided Fluid Management Protocol for the Critically Ill Patient is a prospective, multi-centre, randomized controlled trial. Five hundred ICU patients will be randomly assigned in a 1:1 ratio, to protocolized LUS-based fluid management or usual care. The trial intervention will start on ICU admission and will consist in daily assessment of BLS and triggered evacuation of excessive fluids with loop diuretics (Furosemide) when BLS ≥ 15. If rebalancing volume status with diuretics fails, forced evacuation by ultrafiltration will be used. The main endpoint is death from all causes at 28 days from randomization. The secondary outcomes are presence and time-course evolution of organ dysfunctions, ICU- and hospital length of stay, all-cause mortality at 90 days, and health economics data.

Discussion

If study results will show that LUS guided fluid management protocol improves outcome in ICU patients, it will be the base for other studies to refine this protocol or track those categories of critically ill patients to whom it may bring maximum benefits.

Trial registration

ClinicalTrials.gov, NCT03393065. Registered on 8 January 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3345-0) contains supplementary material, which is available to authorized users.

The Role of Point-of-Care Ultrasound Monitoring in Cardiac Surgical Patients With Acute Kidney Injury

The approach to the patient with acute kidney injury (AKI) after cardiac surgery involves multiple aspects. These include the rapid recognition of reversible causes, the accurate identification of patients who will progress to severe stages of AKI, and the subsequent management of complications resulting from severe renal dysfunction. Unfortunately, the inherent limitations of physical examination and laboratory parameter results are often responsible for suboptimal clinical management. In this review article, the authors explore how point-of-care ultrasound, including renal and extrarenal ultrasound, can be used to complement all aspects of the care of cardiac surgery patients with AKI, from the initial approach of early AKI to fluid balance management during renal replacement therapy. The current evidence is reviewed, including knowledge gaps and future areas of research.

[Pulmonary ultrasound and dialysis]

Profound deficit of the body fluid composition regulation system is present at the end stage kidney disease, leading to the increase the risk of acute or chronic volume overload, which impacts the morbidity and mortality in these patients. Pulmonary ultrasound by its ability to estimate extrapulmonary water at an infraclinical stage has helped to make progress in this area. Line B is the element of fundamental semiology that reflects the presence of water in the pulmonary alveoli. The alteration of left ventricular function and the increase of pulmonary capillary permeability are the determining factors in the genesis of subclinical pulmonary congestion and are positively correlated with B-lines. Because of its non-invasive nature, its ease of use, its intra- and interoperability reproducibility and its ease of learning, nephrologists can be efficiently and quickly trained to use it to measure pulmonary congestion. Recent data have shown an epidemiological association between B-lines and mortality in end stage kidney disease patients. The causal role of subclinical pulmonary congestion assessed by these B lines in the genesis of detrimental events is being evaluated by a randomized, multicentre, open-label European clinical trial (Lung water by ultra-sound guided treatment [LUST] trial). The clinical usefulness of pulmonary ultrasound in the management of subclinical pulmonary congestion in patients with end stage kidney disease remains to be determined, but it could be considered from now as an additional tool to improve the management of this congestion, possibly by complementing bioimpedancemetry data.