Renal ultrasonography in critically ill patients

Impact of positive end-expiratory pressure on renal resistive index in mechanical ventilated patients

PURPOSE

Growing evidence shows the complex interaction between lung and kidney in critically ill patients. The renal resistive index (RRI) is a bedside measurement of the resistance of the renal blood flow and it is correlated with kidney injury. The positive end-expiratory pressure (PEEP) level could affect the resistance of renal blood flow, so we assumed that RRI could help to monitoring the changes in renal hemodynamics at different PEEP levels. Our hypothesis was that the RRI at ICU admission could predict the risk of acute kidney injury in mechanical ventilated critically ill patients.

METHODS

We performed a prospective study including 92 patients requiring mechanical ventilation for ≥ 48 h. A RRI ≥ 0.70, was deemed as pathological. RRI was measured within 24 h from ICU admission while applying 5,10 and 15 cmH2O of PEEP in random order (PEEP trial).

RESULTS

Overall, RRI increased from 0.62 ± 0.09 at PEEP 5 to 0.66 ± 0.09 at PEEP 15 (p < 0.001). The mean RRI value during the PEEP trial was able to predict the occurrence of AKI with AUROC = 0.834 [95%CI 0.742-0.927]. Patients exhibiting a RRI ≥ 0.70 were 17/92(18%) at PEEP 5, 28/92(30%) at PEEP 10, 38/92(41%) at PEEP 15, respectively. Thirty-eight patients (41%) exhibited RRI ≥ 0.70 at least once during the PEEP trial. In these patients, AKI occurred in 55% of the cases, versus 13% remaining patients, p < 0.001.

CONCLUSIONS

RRI seems able to predict the risk of AKI in mechanical ventilated patients; further, RRI values are influenced by the PEEP level applied.

TRIAL REGISTRATION

Clinical gov NCT03969914 Registered 31 May 2019.

Evaluation of Renal Function with Urinary NGAL and Doppler Ultrasonography in ICU Patients: A 1-Year Observational Pilot Study

BACKGROUND

We estimated the diagnostic accuracy of urinary NGAL for the diagnosis of AKI.

METHODS

Urinary NGAL and Creatinine were measured daily for up to 3 days. Doppler ultrasonography was performed within 24 h of admission and for the following 3 days.

RESULTS

Of the 21 patients, 44% had AKI during their ICU stay. The AKI group presented with higher values of serum Creatinine, renal length, MDRD as well as SAPS II already at admission. Urinary NGAL was significantly higher among patients with AKI and patients AKI-no at T0 (p < 0.0001) and increased steadily on T1 and T2. Urinary NGAL seemed to be a notable diagnostic marker for AKI from the first measurement (T0) with an area under the ROC of 0.93 (95% CI = 0.78-0.99) with a sensitivity of 99%. RRI levels were slightly higher in the AKI group at each time and increased gradually from T0 to T2 but reached statistical significance only at T2 (p = 0.02). Renal length and SAPS II at T0 showed high AuRoc and sensitivity.

CONCLUSIONS

Urinary NGAL is a valuable marker for AKI in intensive care settings. It seemed that a pre-existing chronic renal disease, the SAPS II and the NGAL at admission represented the principal predictors of AKI.

Abdominal ultrasound and VExUS score in critical care

The use of ultrasound while caring for critically ill patients has been increasing exponentially in the last two decades and now is an essential component of intensive care practice. Abdominal ultrasound is an established technique in other specialties, but its use in intensive care has lagged behind other ultrasound modalities. However, its potential role in the diagnosis and management of patients will make it an invaluable tool for intensivists. The main use of abdominal ultrasound at the bedside is for free fluid detection in trauma patients. But abdominal ultrasound can also help us diagnose patients with abdominal pain, hypovolemia or anuria, and it can guide us during procedures such as paracentesis or bladder catheter and gastric tube placement.

Predictive performance of renal resistive index, semiquantitative power Doppler ultrasound score and renal venous Doppler waveform pattern for acute kidney injury in critically ill patients and prediction model establishment: a prospective observational study

BACKGROUND

This study aimed to explore the performance of renal resistive index (RRI), semiquantitative power Doppler ultrasound (PDU) score and renal venous Doppler waveform (RVDW) pattern in predicting acute kidney injury (AKI) in critically ill patients and establish prediction models.

METHODS

This prospective observational study included 234 critically ill patients. Renal ultrasound was measured within 24 h after intensive care unit admission. The main outcome was the highest AKI stage within 5 days after admission according to the Kidney Disease Improving Global Outcomes criteria.

RESULTS

Patients in the AKI stage 3 group had significantly higher RRI, RVDW pattern and lower PDU score (p < 0.05). Only lactate, urine volume, serum creatinine (SCr) on admission, PDU score and RVDW pattern were statistically significant predictors (p < 0.05). Model 1 based on these five variables (area under the curve [AUC] = 0.938, 95% confidence interval [CI] 0.899-0.965, p < 0.05) showed the best performance in predicting AKI stage 3, and difference in AUC between it and the clinical model including lactate, urine volume and SCr (AUC = 0.901, 95% CI 0.855-0.936, p < 0.05) was statistically significant (z statistic = 2.224, p = 0.0261). The optimal cut-off point for a nomogram based on Model 1 was ≤127.67 (sensitivity: 95.8%, specificity: 82.3%, Youden's index: 0.781).

CONCLUSIONS

The nomogram model including SCr, urine volume, lactate, PDU score and RVDW pattern upon admission exhibited a significantly stronger capability for AKI stage 3 than each single indicator and clinical model including SCr, urine volume and lactate.

Head to toe ultrasound: a narrative review of experts’ recommendations of methodological approaches

Critical care ultrasonography (US) is widely used by intensivists managing critically ill patients to accurately and rapidly assess different clinical scenarios, which include pneumothorax, pleural effusion, pulmonary edema, hydronephrosis, hemoperitoneum, and deep vein thrombosis. Basic and advanced critical care ultrasonographic skills are routinely used to supplement physical examination of critically ill patients, to determine the etiology of critical illness and to guide subsequent therapy. European guidelines now recommend the use of US for a number of practical procedures commonly performed in critical care. Full training and competence acquisition are essential before significant therapeutic decisions are made based on the US assessment. However, there are no universally accepted learning pathways and methodological standards for the acquisition of these skills.

Therefore, in this review, we aim to provide a methodological approach of the head to toe ultrasonographic evaluation of critically ill patients considering different districts and clinical applications.

Non-invasive Early Prediction of Septic Acute Kidney Injury by Doppler-Based Renal Resistive Indexes Combined With Echocardiographic Parameters: An Experimental Study

Non-invasive early prediction of septic acute kidney injury (S-AKI) is still urgent and challenging. Increased Doppler-based renal resistive index (RRI) has been shown to be associated with S-AKI, but its clinical use is limited, which may be explained by the complex effects of systemic circulation. Echocardiogram allows non-invasive assessment of systemic circulation, which may provide an effective supplement to RRI. To find the value of RRI combined with echocardiographic parameters in the non-invasive early prediction of S-AKI, we designed this experiment with repeated measurements of ultrasonographic parameters in the early stage of sepsis (3, 6, 12, and 24 h) in cecum ligation and puncture (CLP) rats (divided into AKI and non-AKI groups at 24 h based on serum creatinine), with sham-operated group serving as controls. Our results found that RRI alone could not effectively predict S-AKI, but when combined with echocardiographic parameters (heart rate, left ventricular end-diastolic internal diameter, and left ventricular end-systolic internal diameter), the predictive value was significantly improved, especially in the early stage of sepsis (3 h, AUC: 0.948, 95% CI 0.839–0.992, P < 0.001), and far earlier than the conventional renal function indicators (serum creatinine and blood urea nitrogen), which only significantly elevated at 24 h. Our method showed novel advances and potential in the early detection of S-AKI.

Basic ultrasound head-to-toe skills for intensivists in the general and neuro intensive care unit population: consensus and expert recommendations of the European Society of Intensive Care Medicine

Purpose

To provide consensus, and a list of experts’ recommendations regarding the basic skills for head-to-toe ultrasonography in the intensive care setting.

Methods

The Executive Committee of the European Society of Intensive Care (ESICM) commissioned the project and supervised the methodology and structure of the consensus. We selected an international panel of 19 expert clinicians–researchers in intensive care unit (ICU) with expertise in critical care ultrasonography (US), plus a non-voting methodologist. The panel was divided into five subgroups (brain, lung, heart, abdomen and vascular ultrasound) which identified the domains and generated a list of questions to be addressed by the panel. A Delphi process based on an iterative approach was used to obtain the final consensus statements. Statements were classified as a strong recommendation (84% of agreement), weak recommendation (74% of agreement), and no recommendation (less than 74%), in favor or against.

Results

This consensus produced a total of 74 statements (7 for brain, 20 for lung, 20 for heart, 20 for abdomen, 7 for vascular Ultrasound). We obtained strong agreement in favor for 49 statements (66.2%), 8 weak in favor (10.8%), 3 weak against (4.1%), and no consensus in 14 cases (19.9%). In most cases when consensus was not obtained, it was felt that the skills were considered as too advanced. A research agenda and discussion on training programs were implemented from the results of the consensus.

Conclusions

This consensus provides guidance for the basic use of critical care US and paves the way for the development of training and research projects.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06486-z.

Point-of-care ultrasound in a pandemic: Practical guidance in COVID-19 units

The coronavirus disease 2019 (COVID-19) pandemic has stretched our healthcare system to the brink, highlighting the importance of efficient resource utilization without compromising healthcare provider safety. While advanced imaging is a great resource for diagnostic purposes, the risk of contamination and infection transmission is high and requires extensive logistical planning for intrahospital patient transport, healthcare provider safety, and post-imaging decontamination. This dilemma has necessitated the transition to more bedside imaging. More so than ever, during the current pandemic, the clinical utility and importance of point-of-care ultrasound (POCUS) cannot be overstressed. It allows for safe and efficient beside procedural guidance and provides front line providers with valuable diagnostic information that can be acted upon in real-time for immediate clinical decision-making. The authors have been routinely using POCUS for the management of COVID-19 patients both in the emergency department and in intensive care units turned into “COVID-units.” In this article, we review the nuances of using POCUS in a pandemic situation and maximizing diagnostic output from this bedside technology. Additionally, we review various methods and diagnostic uses of POCUS which can replace conventional imaging and bridge current literature and common clinical practices in critically ill patients. We discuss practical guidance and pertinent review of the literature for the most relevant procedural and diagnostic guidance of respiratory illness, hemodynamic decompensation, renal failure, and gastrointestinal disorders experienced by many patients admitted to COVID-units.

Future developments in the imaging of the gastrointestinal tract: the role of ultrasound

PURPOSE OF REVIEW

The purpose of this review is to summarize the utilization and most recent developments with regard to the use of ultrasound when imaging the abdomen and gastrointestinal tract.

RECENT FINDINGS

Although the use of ultrasound to assess the anatomy of the various abdominal organs is well established within radiology and critical care, its use as part of functional and physiological assessment is still evolving. Recent developments have extended the use of ultrasound beyond standard B-mode/2D imaging techniques to incorporate more functional and haemodynamic assessment. These include the use of contrast-enhanced ultrasound (CEUS), elastography, and colour Doppler techniques.

SUMMARY

Whilst Doppler techniques are reasonably well established within critical care ultrasound (CCUS), especially in echocardiography, CEUS and elastography are less well known. CEUS utilizes a purely intravascular contrast agent whilst elastography measures the degree of deformation or stiffness in various organs. Whilst their use individually may be limited; they may play a role in a multiparametric assessment. Mirroring the overall trends in critical care ultrasound development, abdominal ultrasound assessment is best integrated in a holistic approach and adapted to the individual patient.

Multi-organ point-of-care ultrasound for COVID-19 (PoCUS4COVID): international expert consensus

COVID-19 has caused great devastation in the past year. Multi-organ point-of-care ultrasound (PoCUS) including lung ultrasound (LUS) and focused cardiac ultrasound (FoCUS) as a clinical adjunct has played a significant role in triaging, diagnosis and medical management of COVID-19 patients. The expert panel from 27 countries and 6 continents with considerable experience of direct application of PoCUS on COVID-19 patients presents evidence-based consensus using GRADE methodology for the quality of evidence and an expedited, modified-Delphi process for the strength of expert consensus. The use of ultrasound is suggested in many clinical situations related to respiratory, cardiovascular and thromboembolic aspects of COVID-19, comparing well with other imaging modalities. The limitations due to insufficient data are highlighted as opportunities for future research.

Renal echography for predicting acute kidney injury in critically ill patients: a prospective observational study

Objective

To investigate the diagnostic performances of renal resistive index (RRI) and semiquantitative power Doppler ultrasound (PDU) scores in predicting acute kidney injury (AKI) stage 3 in critically ill patients.

Methods

This prospective observational study included 148 patients (80 with reduced cardiac index [CI], 68 with maintained CI). RRI and semiquantitative PDU scores were measured within 6 h after intensive care unit admission. AKI was defined according to Kidney Disease Improving Global Outcomes criteria.

Results

A negative correlation between RRI and PDU score (r = −0.517, p < 0.001) and a positive correlation between PDU score and CI (r = 0.193, p = 0.019) were found, whereas RRI was not correlated with CI (r = 0.131, p = 0.121). The predictive value of RRI for AKI stage 3 was similar between CI-reduced (area under the curve [AUC] 0.761, 95% confidence interval 0.650–0.851, p < 0.001) and CI-maintained (AUC 0.786, 95% confidence interval 0.665–0.878, p < 0.001) patients. Conversely, PDU score could effectively predict AKI stage 3 in CI-reduced patients (AUC 0.872, 95% confidence interval 0.778–0.936, p < 0.001) but not in CI-maintained patients (AUC 0.669, 95% confidence interval 0.544–0.778, p = 0.071). The predictive value of PDU score for AKI stage 3 was statistically different between CI-reduced and CI-maintained patients (p = 0.021).

Conclusions

PDU scores could effectively predict AKI stage 3 in CI-reduced patients but not in CI-maintained patients. RRI is a poor predictor of AKI stage 3 in patients with reduced or maintained CI.

Measures of adiposity correlate with renal filtration in young nulliparous women: An observational cohort study

OBJECTIVE

Renal hyperfiltration, which has been documented in severe obesity and obesity-associated hypertension, can occur with hypertensive disorders of pregnancy. Identification of prepregnancy risk factors for unrecognized renal hyperfiltration could inform screening and intervention strategies to protect against pregnancy complications. In young, healthy, nulliparous women, associations between associations between measures of adiposity, insulin resistance, and renal vascular resistance were thus evaluated.

METHODS

This is a secondary analysis of a prospective observational trial characterizing associations of prepregnancy and late-pregnancy maternal physiology. Seventy-nine nulligravid women aged 18-42 years without major medical conditions were assessed for percent android body fat using dual-energy X-ray absorption. Renal cortical vessel blood flow resistance index (CVRI) was determined using Doppler ultrasonography. Creatinine clearance was calculated from 24-hour urine collection.

RESULTS

Renal CVRI inversely correlates with body mass index (r = -0.23, p = 0.047), percent android fat (r = -0.30, p = 0.008), and supine pulse (r = -0.44, p < 0.001). Creatinine clearance is positively associated with BMI and HOMA-IR.In regression modeling, supine pulse (r2 = 0.22, p < 0.001) and cardiac index (r2 = 0.05, p = 0.045) predict renal CVRI, whereas HOMA-IR (r2 = 0.11, p = 0.008) and cardiac output (r2 = 0.06, p = 0.039) predict creatinine clearance. Measures of adiposity are not independently predictive of either measure.

CONCLUSIONS

In healthy young women, measures of adiposity and insulin resistance correlate positively with renal filtration. Preclinical manifestations of renal hyperfiltration may have implications for pregnancy outcomes.

Semiquantitative Power Doppler Ultrasound Score to Predict Acute Kidney Injury in Patients With Sepsis or Cardiac Failure: A Prospective Observational Study

BACKGROUND

Diagnosing acute kidney injury (AKI) stage 3 in critically ill patients may help physicians in making treatment decisions. This diagnosis relies chiefly on urinary output and serum creatinine, which may be of limited value. This study aimed to explore the diagnostic performance of renal resistive index (RRI) and semiquantitative power Doppler ultrasound (PDU) scores in predicting AKI stage 3 in patients with sepsis or cardiac failure.

METHODS

This study is a prospective observational study that included 83 patients (40 with sepsis and 43 with cardiac failure). Renal resistive index and semiquantitative PDU scores were measured within 6 hours following admission to the intensive care unit. Acute kidney injury was defined according to the criteria set by Kidney Disease Improving Global Outcomes.

RESULTS

The predictive values of RRI (area under the curve [AUC] = 0.772, 95% confidence interval [CI] = 0.658-0.886) and PDU score (AUC = 0.780, 95% CI = 0.667-0.892) were similar in all patients. Power Doppler ultrasound score (AUC = 0.910, 95% CI = 0.815-1.000) could effectively predict AKI stage 3 in the cardiac failure subgroup, and the optimal cutoff for this parameter was ≤ 1 (sensitivity = 87.5%, specificity = 92.6%, Youden index = 0.801, accuracy in our population = 90.7%). However, PDU scores (AUC = 0.620, 95% CI = 0.425-0.814) could not predict AKI stage 3 in the sepsis subgroup. The predictive values of RRI for AKI stage 3 in the cardiac failure (AUC = 0.820, 95% CI = 0.666-0.974) and sepsis (AUC = 0.724, 95% CI = 0.538-0.910) subgroups were similar.

CONCLUSIONS

Power Doppler ultrasound scores could effectively predict AKI stage 3 in patients with cardiac failure but not in patients with sepsis. Renal resistive index is a poor predictor of AKI stage 3 in patients with sepsis or cardiac failure.

Whole body ultrasound in the operating room and intensive care unit

Whole body ultrasound can be used to improve the speed and accuracy of evaluation of an increasing number of organ systems in the critically ill. Cardiac and abdominal ultrasound can be used to identify the mechanisms and etiology of hemodynamic instability. In hypoxemia or hypercarbia, lung ultrasound can rapidly identify the etiology of the condition with an accuracy that is equivalent to that of computed tomography. For encephalopathy, ocular ultrasound and transcranial Doppler can identify elevated intracranial pressure and midline shift. Renal and bladder ultrasound can identify the mechanisms and etiology of renal failure. Ultrasound can also improve the accuracy and safety of percutaneous procedures and should be currently used routinely for central vein catheterization and percutaneous tracheostomy.

Prediction of acute kidney injury: the ratio of renal resistive index to semiquantitative power Doppler ultrasound score-a better predictor?: A prospective observational study

This study aimed to explore the diagnostic performance of the ratio of renal resistive index (RRI) to semiquantitative power Doppler ultrasound (PDU) score in predicting acute kidney injury (AKI) 3 in critically ill patients.This study was a prospective, observational study that included 101 critically ill patients. RRI and semiquantitative PDU score were measured within 6 hours following admission to the intensive care unit (ICU). The ratio of RRI to PDU (RRI/PDU) was calculated as follows: RRI / PDU. If PDU score was 0, the RRI/PDU was 1. Meanwhile, AKI was defined according to the Kidney Disease Improving Global Outcomes criteria.Median RRI/PDU was 0.234 (0.190, 0.335) in patients with AKI 0-2 and 0.636 (0.411, 0.738) in patients with AKI 3 (P < .001). As assessed by the area under the receiver operator characteristic curves (AUC), RRI/PDU performed best in diagnosing AKI 3 [AUC = 0.935 (95% CI: 0.868-0.974)]. Optimal cuto for RRI/PDU was > 0.37, and the sensitivity and specificity were 90.5% and 90.0%, respectively. In 93 patients, except for 8 patients with a PDU score of 0, the AUC of RRI/PDU [0.938 (95% CI: 0.868-0.977)] was superior to the PDU score (0.905 [95% CI: 0.826-0.956], P = .133), RRI [0.782 (95% CI: 0.684-0.861), P = .016], serum creatinine [0.801 (95% CI: 0.705-0.877), P = .017], or 6 hours AKI stage (0.876 [95% CI: 0.791-0.935], P = .110) in predicting AKI 3 on D5.In our study, RRI, PDU score, RRI/PDU, and 6 hours AKI stage were useful in predicting AKI 3. Furthermore, RRI/PDU may be a better predictor of AKI 3.

Can Renal Resistive Index Predict Acute Kidney Injury After Acute Type A Aortic Dissection Repair?

BACKGROUND

This study sought to determine whether assessment of the renal resistive index (RRI) can predict the short-term reversibility of acute kidney injury (AKI) after repair of acute type A aortic dissection (TAAD).

METHODS

This prospective study included 62 patients undergoing repair of acute TAAD. Doppler-based RRIs were obtained preoperatively, immediately after the surgical procedure, and 6, 24, and 48 hours postoperatively. The occurrence of AKI was evaluated daily according to Acute Kidney Injury Network criteria. Persistent AKI was defined as AKI lasting longer than 3 days. The association between the maximum RRI level at different time points and persistent AKI was analyzed by the receiver-operating characteristic curve.

RESULTS

Of the 62 patients, 22 (35.5%) had no AKI, 21 (33.9%) had transient AKI, and 19 (30.6%) had persistent AKI. The maximum RRI was 0.67 ± 0.03 (0.62 to 0.71), 0.71 ± 0.05 (0.59 to 0.79), and 0.78 ± 0.05 (0.70 to 0.92) in the no AKI, transient AKI, and persistent AKI groups, respectively. The maximum level of RRI was significantly correlated with that of SCr during the first 48 hours postoperatively (rho = 0.606; p < 0.001). RRI could predict persistent AKI with an area under the receiver-operating characteristic curve of 0.918 (95% confidence interval, 0.850 to 0.986; p < 0.001). A postoperative RRI of 0.725 or higher was a marker for early detection of persistent AKI with high sensitivity and specificity (94.7% and 72.1%, respectively).

CONCLUSIONS

An elevated maximum RRI may be a predictor of persistent AKI after repair of acute TAAD. This is helpful for management decision making and improving the prognosis of patients with AKI.

Diagnostic work-up and specific causes of acute kidney injury

Acute kidney injury (AKI) is common in critically ill patients and associated with grim short- and long-term outcome. Although in the vast majority of cases AKI is multifactorial, with sepsis, shock and nephrotoxicity accounting for most episodes, specific causes of AKI are not uncommon. Despite remaining uncertainties regarding their prevalence in the ICU, prompt recognition of specific aetiologies of AKI is likely to ensure timely management, limit worsening of renal dysfunction, and ultimately limit renal and systemic consequences of AKI. The ability to recognize conditions that may be associated with specific aetiologies and the appropriate use of clinical imaging, biological and immunological tests, along with optimal assessment of the need for renal biopsies, should be part of routine ICU care. In this review, we summarize uncertainties, current knowledge and recent advances regarding specific types of AKI. We describe the most common specific causes as well as rare aetiologies requiring urgent management, and outline available tools that may be used during the diagnostic work-up along with their limitations.

Overview of point-of-care abdominal ultrasound in emergency and critical care

Point-of-care abdominal ultrasound (US), which is performed by clinicians at bedside, is increasingly being used to evaluate clinical manifestations, to facilitate accurate diagnoses, and to assist procedures in emergency and critical care. Methods for the assessment of acute abdominal pain with point-of-care US must be developed according to accumulated evidence in each abdominal region. To detect hemoperitoneum, the methodology of a focused assessment with sonography for a trauma examination may also be an option in non-trauma patients. For the assessment of systemic hypoperfusion and renal dysfunction, point-of-care renal Doppler US may be an option. Utilization of point-of-care US is also considered in order to detect abdominal and pelvic lesions. It is particularly useful for the detection of gallstones and the diagnosis of acute cholecystitis. Point-of-case US is justified as the initial imaging modality for the diagnosis of ureterolithiasis and the assessment of pyelonephritis. It can be used with great accuracy to detect the presence of abdominal aortic aneurysm in symptomatic patients. It may also be useful for the diagnoses of digestive tract diseases such as appendicitis, small bowel obstruction, and gastrointestinal perforation. Additionally, point-of-care US can be a modality for assisting procedures. Paracentesis under US guidance has been shown to improve patient care. US appears to be a potential modality to verify the placement of the gastric tube. The estimation of the amount of urine with bladder US can lead to an increased success rate in small children. US-guided catheterization with transrectal pressure appears to be useful in some male patients in whom standard urethral catheterization is difficult. Although a greater accumulation of evidences is needed in some fields, point-of-care abdominal US is a promising modality to improve patient care in emergency and critical care settings.

[Point-of-care ultrasound in Spanish paediatric intensive care units]

INTRODUCTION

Point-of-care (bedside) ultrasound is being increasingly used by paediatricians who treat critically ill children. The aim of this study is to describe its availability, use, and specific training in Paediatric Intensive Care Units in Spain.

MATERIAL AND METHODS

A descriptive, cross-sectional, multicentre study was performed using an online survey.

RESULTS

Of a total of 51 PICUs identified in our country, 64.7% responded to the survey. Just over half (53.1%) have their own ultrasound machine, 25% share it, with other units with the usual location in the PICU, and 21.9% share it, but it is usually located outside the PICU. Ultrasound machine availability was not related to size, care complexity, or number PICU admissions. The ultrasound was used daily in 35% of the units, and was associated with location of the machine in the PICU (P=.026), the existence of a transplant program (P=.009), availability of ECMO (P=.006), and number of admissions (P=.015). 45.5% of PICUs has less than 50% of the medical staff specifically trained in bedside ultrasound, and 18.2% have all their medical staff trained. The presence of more than 50% of medical staff trained was associated with a higher rate of daily use (P=.033), and with specific use to evaluate cardiac function (P=.033), intravascular volume estimation (P=.004), or the presence of intra-abdominal collections (P=.021).

CONCLUSIONS

Bedside ultrasound is frequently available in Spanish PICUs. Specific training is still variable, but it should serve to enhance its implementation.

Renal Doppler Resistive Index as a Marker of Oxygen Supply and Demand Mismatch in Postoperative Cardiac Surgery Patients

Background and Objective. Renal Doppler resistive index (RDRI) is a noninvasive index considered to reflect renal vascular perfusion. The aim of this study was to identify the independent hemodynamic determinants of RDRI in mechanically ventilated patients after cardiac surgery. Methods. RDRI was determined in 61 patients by color and pulse Doppler ultrasonography of the interlobar renal arteries. Intermittent thermodilution cardiac output measurements were obtained and blood samples taken from the tip of pulmonary artery catheter to measure hemodynamics and mixed venous oxygen saturation (SvO₂). Results. By univariate analysis, RDRI was significantly correlated with SvO₂, oxygen extraction ratio, left ventricular stroke work index, and cardiac index, but not heart rate, central venous pressure, mean artery pressure, pulmonary capillary wedge pressure, systemic vascular resistance index, oxygen delivery index, oxygen consumption index, arterial lactate concentration, and age. However, by multivariate analysis RDRI was significantly correlated with SvO₂ only. Conclusions. The present data suggests that, in mechanically ventilated patients after cardiac surgery, RDRI increases proportionally to the decrease in SvO₂, thus reflecting an early vascular response to tissue hypoxia.

Bedside Doppler ultrasound for the assessment of renal perfusion in the ICU: advantages and limitations of the available techniques

Three Doppler-derived techniques have been proposed to assess renal perfusion at bedside: Doppler-based renal resistive index (RI) which has been extensively but imperfectly studied in assessing renal allograft status and changes in renal perfusion in critically ill patients and for predicting the reversibility of an acute kidney injury (AKI), semi-quantitative evaluation of renal perfusion using colour-Doppler which may be easier to perform and may give similar information than RI and contrast-enhanced sonography that may allow more precise renal and cortical perfusion assessment. These promising tools have several obvious advantages including their feasibility, non-invasiveness, repeatability and potential interest in assessing renal function or perfusion. However, several limits need to be taken into account with these techniques, and promising results remain associated with large areas of uncertainty. This editorial will describe more carefully advantages and limits of these techniques and will discuss their potential interest in assessing renal perfusion.

Whole-body ultrasound in the intensive care unit: a new role for an aged technique

Management of critically ill patients requires rapid and safe diagnostic techniques. Ultrasonography has become an indispensable tool that supplements physical examination in the intensive care unit. It enables early recognition of neurological emergencies, assists the diagnosis of abdominal and lung pathologies, and provides real-time information on the cardiac performance of critically ill patients. Furthermore, it detects possible infectious sites and renders therapeutic invasive procedures more convenient and less complicated. Whole-body ultrasound in the hands of adequately trained intensivists has the ability to reinvigorate the physical examination, without subjecting the patient to excessive irradiation and the risks of transport.

Ultrasound in the surgical intensive care unit

PURPOSE OF REVIEW

Critically ill patients are subjected to a variety of diagnostic and therapeutic procedures. It is desirable to make these interventions as timely, safe, and effective as possible. Bedside ultrasound and echocardiography are tools that allow for diagnosis of many conditions, without subjecting the patient to radiation, dye, and the risks of transport. In addition, ultrasound guidance of procedures may improve safety and efficacy. This review analyzes the literature on ultrasound and echocardiography use in the ICU.

RECENT FINDINGS

There is evidence supporting the use of bedside echocardiography and ultrasound for the diagnosis of chest, abdominal, and other pathologic conditions in the ICU. There is also evidence to support ultrasound guidance of vascular access and other procedures. There are multiple reports of novel uses of bedside echocardiography and ultrasound in the ICU.

SUMMARY

There is substantial literature supporting ultrasound and bedside limited echocardiography in the critical care setting. In addition, there are frequent reports of new applications for these technologies in the literature. The role of ultrasound and bedside limited echocardiography in the critical care setting is likely to expand in the future and become a part of daily care in every surgical intensive care unit.