The Role of Ultrasonographic Inferior Vena Cava Measurement in the Volume-Based Classification of Patients With Hyponatremia.

OBJECTIVES: To demonstrate the role of inferior vena cava (IVC) collapsibility in the assessment of volume status in hyponatremic critically ill patients in the emergency department (ED) with bedside IVC imaging and to predict volume status with response to fluid therapy. METHODS: A prospective 110 hypotonic hyponatremic patients aged >18 years with a serum sodium level under 125 mEq/L and at least one symptom of hyponatremia, who presented or referred to the ED was conducted. Demographical, clinical, and laboratory characteristics with bedside measurement of IVC diameter of patients were recorded. Volume status was divided into 3 subgroups: hypovolemic-G1, euvolemic-G2, and hypervolemic-G3. An ED trainee with a certification to perform basic and advanced ultrasonography (USG) training carried out the USG examinations. A diagnostic algorithm approach was made according to the results. RESULTS: Symptom severity was significantly greater in the hypervolemic group than the other groups (P = .009 and P = .034, respectively). Systolic blood pressure (SBP) and mean arterial pressure (MAP) were significantly lower in the hypovolemic group compared with the other groups (P < .001 and P = .003, respectively). There was a significant difference between the ultrasonographically measured IVC min, IVC max, and mean IVC values across the three volume-based groups (P < .001). CONCLUSION: Considering the diversity of physical examination (PE) findings, with the highly heterogenous nature of hyponatremia, a new measurable algorithm can be developed on the basis of contemporary hyponatremic patient management guidelines.

A comprehensive echocardiographic analysis during simulated hypovolaemia: An observational study.

BACKGROUND: Peri-operative and critically ill patients often experience mild to moderate hypovolaemic shock with preserved mean arterial pressure (MAP), heart rate (HR) and decreased stroke volume index (SVI). OBJECTIVES: The aim of this study was to evaluate echocardiographic parameters during simulated mild to moderate central hypovolaemia. DESIGN: This was a prospective preclinical study. SETTING: Laboratory trial performed in Charité-Universitätsmedizin Berlin, Germany. PATIENTS AND METHODS: Thirty healthy male volunteers underwent graded central hypovolaemia using a lower body negative pressure (LBNP) chamber with a stepwise decrease to simulate a mild (-15 mmHg), mild-to-moderate (-30 mmHg), and moderate state of hypovolaemic shock (-45 mmHg). During every stage, a transthoracic echocardiography examination (TTE) was performed by a certified examiner. MAIN OUTCOME MEASURES: Systolic and diastolic myocardial performance markers, as well as cardiac volumes were recorded during simulated hypovolaemia and compared to baseline values. RESULTS: During simulated hypovolaemia via LBNP, SVI decreased progressively at all stages, whereas MAP and HR did not consistently change. Left ventricular (LV) ejection fraction decreased at -30 and -45 mmHg. Simultaneously with SVI decline, LV global longitudinal strain (LV GLS), tricuspid annular plain systolic excursion (TAPSE), and right ventricular RV S' and left-atrial end-systolic volume (LA ESV) decreased compared to baseline at all stages. CONCLUSIONS: In this study, simulated central hypovolaemia using LBNP did not induce consistent changes in MAP and HR. SVI decreased and was associated with deteriorated right- and left-ventricular function, observed with echocardiography. The decreased filling status was characterised by decreased LA ESV. CLINICAL TRIAL NUMBER: ClinicalTrials.gov Identifier: NCT03481855.

Hepatorenal syndrome misdiagnosis may be reduced using inferior vena cava ultrasound to assess intravascular volume and guide management.

Hepatorenal syndrome (HRS) is a diagnosis of exclusion defined as acute kidney injury (AKI) with cirrhosis and ascites, with serum creatinine unresponsive to standardized volume administration and diuretic withdrawal. Persistent intravascular hypovolemia or hypervolemia may contribute to AKI and be revealed by inferior vena cava ultrasound (IVC US), which may guide additional volume management. Twenty hospitalized adult patients meeting HRS-AKI criteria had IVC US to assess intravascular volume after receiving standardized albumin administration and diuretic withdrawal. Six had IVC collapsibility index (IVC-CI) ≥50% and IVCmax ≤0.7 cm suggesting intravascular hypovolemia, 9 had IVC-CI <20% and IVCmax >0.7 cm suggesting intravascular hypervolemia, and 5 had IVC-CI ≥20% to <50% and IVCmax >0.7 cm. Additional volume management was prescribed in the 15 patients with either hypovolemia or hypervolemia. After 4-5 days, serum creatinine levels decreased ≥20% without hemodialysis in 6 of 20 patients - 3 with hypovolemia received additional volume, and 2 with hypervolemia plus one with 'euvolemia' and dyspnea were volume restricted and received diuretics. In the other 14 patients, serum creatinine failed to persistently decrease ≥20% or hemodialysis was required indicating that AKI did not improve. In summary, fifteen of 20 patients (75%) were presumed to have intravascular hypovolemia or hypervolemia by IVC ultrasound. Six of the 20 patients (40%) improved AKI by 4-5 days of follow-up with additional IVC US-guided volume management, and thus had been misdiagnosed as HRS-AKI. IVC US may more accurately define HRS-AKI as being neither hypovolemic nor hypervolemic, and guide volume management, decreasing the frequency of HRS-AKI misdiagnosis.

The role of tricuspite annular plane systolic excursion as a marker of hypovolemia in healthy blood donor volunteers.

AIM: The aim of this study is to compare the diameter of the inferior vena cava with tricuspid annular plane systolic excursion (TAPSE) measurement in order to determine the volume loss before and after blood donation in healthy volunteers. METHODS: This Institutional Review Board-approved single center, prospective, cross-sectional study included 60 healthy blood donors donating in a tertiary care hospital's blood bank. After obtaining written consent, systolic, diastolic, and mean arterial blood pressures along with pulse rate of the donors were measured in sitting and supine positions by the attending physician, then, inferior vena cava (IVC) and TAPSE measurements were made before and after blood donation. RESULTS: Statistically significant differences was found between standing systolic blood pressure and pulse rate, lying systolic blood pressure and pulse rate, IVC and TAPSE values before and after blood donation (p < 0.05). There was no difference between the other variables before and after blood donation. CONCLUSION: Our study revealed that, low IVC and TAPSE values correlated in determining blood loss after blood donation. TAPSE may be useful to predict blood loss in early stages of hypovolemic shock.

Measuring the ratio of femoral vein diameter to femoral artery diameter by ultrasound to estimate volume status.

BACKGROUND: Currently, the accepted effective method for assessing blood volume status, such as measuring central venous pressure (CVP) and mean pulmonary artery pressure (mPAP), is invasive. The purpose of this study was to explore the feasibility and validity of the ratio of the femoral vein diameter (FVD) to the femoral artery diameter (FAD) for predicting CVP and mPAP and to calculate the cut-off value for the FVD/FAD ratio to help judge a patient's fluid volume status. METHODS: In this study, 130 patients were divided into two groups: in group A, the FVD, FAD, and CVP were measured, and in group B, the FVD, FAD, and mPAP were measured. We measured the FVD and FAD by ultrasound. We monitored CVP by a central venous catheter and mPAP by a Swan-Ganz floating catheter. Pearson correlation coefficients were calculated. The best cut-off value for the FVD/FAD ratio for predicting CVP and mPAP was obtained according to the receiver operating characteristic (ROC) curve. RESULTS: The FVD/FAD ratio was strongly correlated with CVP (R = 0.87, P < 0.0000) and mPAP (R = 0.73, P < 0.0000). According to the ROC curve, an FVD/FAD ratio ≥ 1.495 had the best test characteristics to predict a CVP ≥ 12 cmH2O, and an FVD/FAD ratio ≤ 1.467 had the best test characteristics to predict a CVP ≤ 10 cmH2O. An FVD/FAD ratio ≥ 2.03 had the best test characteristics to predict an mPAP ≥ 25 mmHg. According to the simple linear regression curve of the FVD/FAD ratio and CVP, when the predicted CVP ≤ 5 cmH2O, the FVD/FAD ratio was ≤ 0.854. CONCLUSION: In this study, the measurement of the FVD/FAD ratio obtained via ultrasound was strongly correlated with CVP and mPAP, providing a non-invasive method for quickly and reliably assessing blood volume status and providing good clinical support.

Assessment of cerebral and renal autoregulation using near-infrared spectroscopy under normal, hypovolaemic and postfluid resuscitation conditions in a swine model: An observational study.

BACKGROUND: The impact of blood pressure changes on tissue oxygenation differs between vital organs and with blood volume conditions. OBJECTIVE: To assess cerebral and renal autoregulation simultaneously and compare the impact of blood pressure, hypovolaemia and fluid resuscitation on tissue oxygenation using near-infrared spectroscopy. DESIGN: Animal observational study. SETTING: An animal laboratory in Hamamatsu University School of Medicine, Hamamatsu, Japan, from April 2018 to August 2018. ANIMALS: Fifteen pigs, (mean ±â€ŠSD) 25.2 ±â€Š0.4 kg. INTERVENTIONS: The pigs were anaesthetised with 2.5% isoflurane and phenylephrine 0.5, 1, 2 and 5 µg kg min was administered in a stepwise fashion at 10-min intervals (baseline), followed by similar administration of sodium nitroprusside. Hypovolaemia was induced by a 600-ml bleed (33% of estimated total blood volume). Then phenylephrine was administered again (same protocol). Hypovolaemia was reversed by infusion of 600-ml hydroxyethyl starch. Phenylephrine and sodium nitroprusside were then administered again (same protocol). MAIN OUTCOME MEASURES: Average of the relation between mean arterial pressure (MAP) and cerebral or renal tissue oxygenation index (TOI) and individual TOI response during vasoactive drug infusions. RESULTS: The average relationship between MAP and cerebral or renal TOI both showed classic autoregulation patterns, whereas the renal TOI was more pressure-dependent than the cerebral TOI. Hypovolaemia shifted the relationship downward, reducing the cerebral and renal TOIs by approximately 5 and 20%, respectively, at similar MAPs. Subsequent fluid resuscitation preserved the autoregulatory pattern in both organs, not changing cerebral TOI but reducing renal TOI to 10% under baseline. TOI responses in both organs included paradoxical changes (tissue oxygenation changed inversely with MAP) in 60% of animals. Animals with paradoxical reactions maintained more stable cerebral and renal oxygenation. CONCLUSION: Renal oxygenation is more pressure-dependent than pressure-tolerant cerebral oxygenation, and autoregulation is not robust. Renal oxygenation decreased four-fold compared with cerebral oxygenation during hypovolaemia and two-fold during isovolaemic anaemia. Thus, paradoxical responses are part of normal autoregulatory function and beneficial for maintaining stable oxygenation.

Comparison of inferior vena cava collapsibility, distensibility, and delta indices at different positive pressure supports and prediction values of indices for intravascular volume status

Background/aim: To compare the inferior vena cava (IVC) indices, identify their variation rates at positive pressure values and accurate predictive values for the volume status in patients with spontaneous respiration receiving different positive pressure support. Materials and methods: The study included 100 patients who were divided into 4 pressure support groups, according to the different pressure supports received, and 3 volume groups according to their CVP values. Ultrasonography was applied to all of the patients to define their IVC diameters at different pressure supports. Dynamic parameters were derived from the ultrasonographic assessment of the IVC diameter [collapsibility (CI-IVC), distensibility (dIVC), and delta (ΔIVC) indices]. Results: There were significant differences between the 3 indices (CI-IVC, dIVC, and ΔIVC) according to the pressure groups [(10/5), (10/0), (0/5), (t tube 0/0)]. The median value for the dIVC percentages was ≤18% for all of the positive pressure support hypervolemic groups, apart from the hypervolemic t tube group (19%). For the hypervolemic groups, the best estimation according to the cut-off value appeared to be for the dIVC. Values with the highest sensitivity for differentiation of the hypovolemic individuals were calculated with the dIVC. Conclusion: The dIVC had a more accurate predictive role in predicting the volume status when compared with the CI-IVC and ΔIVC, and may be used reliably with positive pressure supports.

Image-Guided Resuscitation With Limited Transthoracic Echocardiogram in Pediatric Trauma Patients.

INTRODUCTION: Limited transthoracic echocardiogram (LTTE) has been shown to be a useful tool in guiding resuscitation in adult trauma patients. Our hypothesis is that image-guided resuscitation in pediatric trauma patients with LTTE is feasible. METHODS: A retrospective chart review was performed on highest level pediatric trauma alerts (age 18 years or younger) at our level I trauma center during a 6-month period. Patients were divided into 2 groups as follows: those who had LTTE performed (LTTE group) and those who did not have LTTE performed (non-LTTE group). RESULTS: A total of 31 charts were reviewed; 4 patients were excluded because they died on arrival to the emergency department. Fourteen patients had LTTE performed (LTTE group); 13 patients did not have LTTE performed (non-LTTE group). There was no difference in mechanism of injury, age, injury severity score, weight, or intensive care unit admission between the groups. The LTTE group received significantly less intravenous fluid than the non-LTTE group (1.2 vs 2.3 L, P = 0.0013).Within the LTTE group, 8 patients had "full" inferior vena cava (IVC) and 6 patients had "empty" IVC. There was no difference in injury severity score between these subgroups (P = 0.1018). Less fluid was given in the group labeled with full IVC [1.1 L (0.8-1.2)] than the group with empty IVC [2.4 L (1.7-2.6)], P = 0.0005. Four of the 6 patients with "empty" IVC had a confirmed source of bleeding. CONCLUSIONS: Limited transthoracic echocardiogram can limit the amount of unnecessary crystalloid resuscitation given to pediatric trauma patients who are not hypovolemic.

Assessment of Fluid responsiveness in the Acute Medical Patient and the Role of Echocardiography.

Both hyper and hypovolaemia have been associated with poor outcomes. Assessment of fluid responsiveness is challenging in the acute medical patient, due to time constraints, limited evidence and quite often the lack of accurate assessment tools on the Acute Medicine Unit (AMU). This article explains how focused echo assessment is quick and easy to use for this purpose on the acute medical take and highlights key principles to bear in mind when assessing for hypovolaemia and whether to administer fluid therapy. The increasing familiarity with focused echo such as Focused Intensive Care Echocardiography (FICE) and Point Of Care Ultrasound (POCUS) makes extension of these skill sets to assess for fluid responsiveness a relatively straightforward next step for acute physicians.

Severe cerebral hypovolemia on perfusion CT and lower body weight are associated with parenchymal haemorrhage after thrombolysis.

INTRODUCTION: Haemorrhagic transformation of acute ischemic stroke (AIS) and particularly parenchymal haemorrhage (PH) remains a feared complication of intravenous thrombolysis (IVT). We aimed to identify clinical and perfusion CT (PCT) variables which are independently associated with PHs. METHODS: In this observational cohort study, based on the Acute Stroke Registry Analysis of Lausanne (ASTRAL) from 2003 to December 2013, we selected patients with AIS involving the middle cerebral artery (MCA) territory who were thrombolysed within 4.5 h of symptoms' onset and who had a good quality baseline PCT at the beginning of IVT. In addition to demographic, clinical, laboratory and non-contrast CT data, volumes of salvageable tissue and ischemic core on PCT, as well as absolute CBF and CBV values within the ischemic regions were compared in patients with and without PH in multivariate analysis. RESULTS: Of the 190 included patients, 24 (12.6%) presented a PH (11 had PH1 and 13 had PH2). In multivariate analysis of the clinical and radiological variables, the lowest CBV in the core and lower body weight was both significantly associated with PH (p = 0.009 and p = 0.024, respectively). CONCLUSION: In thrombolysed MCA strokes, maximal hypoperfusion severity depicted by lowest CBV values in the core region and lower body weight are independently correlated with PH. This information, if confirmed in other case series, may add to the stratification of revascularisation decisions in patients with a perceived high PH risk.

Ultrasonographic measurements of the inferior vena cava variation as a predictor of fluid responsiveness in patients undergoing anesthesia for surgery.

BACKGROUND: Both hypovolemia and hypervolemia are connected with increased morbidity and mortality in the treatment and prognosis of patients. An accurate assessment of volume state allows the optimization of organ perfusion and oxygen supply. Recently, ultrasonography has been used to detect hypovolemia in critically ill patients and perioperative patients. The objective of our study was to assess the correlation between inferior vena cava (IVC) variation obtained with ultrasound and stroke volume variation (SVV) measured by the Vigileo/FloTrac monitor, as fluid responsiveness indicators, in patients undergoing anesthesia for surgery. METHODS: Forty patients (American Society of Anesthesiologists grades I and II) scheduled for elective gastrointestinal surgery were enrolled in our study. After anesthesia induction, 6% hydroxyethyl starch solution was administered to patients as an intravenous (IV) fluid. The IVC diameters were measured with ultrasonography. SVV and stroke volume index (SVI) were obtained from the Vigileo monitor. All data were collected both before and after fluid challenge. RESULTS: Forty patients underwent IVC sonographic measurements and SVV calculation. After fluid challenge, mean arterial pressure, central venous pressure, SVI, and IVC diameters increased significantly, whereas SVV decreased markedly. The correlation coefficient between the increase in SVI and the baseline of IVC variation after an IV fluid was 0.710, and receiver operating characteristic (ROC) curve was 0.85. The correlation coefficient between the increase in SVI and the baseline of SVV was 0.803 with an ROC curve of 0.93. Central venous pressure had no significant correlation with SVI. CONCLUSIONS: Our data show that IVC variation and SVV proved to be reliable predictors of fluid responsiveness in patients undergoing anesthesia for surgery with mechanical ventilation.

Does inferior vena cava respiratory variability predict fluid responsiveness in spontaneously breathing patients?

INTRODUCTION: We have almost no information concerning the value of inferior vena cava (IVC) respiratory variations in spontaneously breathing ICU patients (SBP) to predict fluid responsiveness. METHODS: SBP with clinical fluid need were included prospectively in the study. Echocardiography and Doppler ultrasound were used to record the aortic velocity-time integral (VTI), stroke volume (SV), cardiac output (CO) and IVC collapsibility index (cIVC) ((maximum diameter (IVCmax)- minimum diameter (IVCmin))/ IVCmax) at baseline, after a passive leg-raising maneuver (PLR) and after 500 ml of saline infusion. RESULTS: Fifty-nine patients (30 males and 29 females; 57 ± 18 years-old) were included in the study. Of these, 29 (49 %) were considered to be responders (≥10 % increase in CO after fluid infusion). There were no significant differences between responders and nonresponders at baseline, except for a higher aortic VTI in nonresponders (16 cm vs. 19 cm, p = 0.03). Responders had a lower baseline IVCmin than nonresponders (11 ± 5 mm vs. 14 ± 5 mm, p = 0.04) and more marked IVC variations (cIVC: 35 ± 16 vs. 27 ± 10 %, p = 0.04). Prediction of fluid-responsiveness using cIVC and IVCmax was low (area under the curve for cIVC at baseline 0.62 ± 0.07; 95 %, CI 0.49-0.74 and for IVCmax at baseline 0.62 ± 0.07; 95 % CI 0.49-0.75). In contrast, IVC respiratory variations >42 % in SBP demonstrated a high specificity (97 %) and a positive predictive value (90 %) to predict an increase in CO after fluid infusion. CONCLUSIONS: In SBP with suspected hypovolemia, vena cava size and respiratory variability do not predict fluid responsiveness. In contrast, a cIVC >42 % may predict an increase in CO after fluid infusion.

Sports medicine ultrasound (US) beyond the musculoskeletal system: use in the abdomen, solid organs, lung, heart and eye.

The use of point-of-care ultrasound (US) by non-radiologists is not new and the expansion into sports medicine practice is relatively young. US has been used extensively to evaluate the musculoskeletal system including the diagnosis of muscle, tendon and bone injuries. However, as sports medicine practitioners we are responsible for the care of the entire athlete. There are many other non-musculoskeletal applications of US in the evaluation and treatment of the athlete. This paper highlights the use of US in the athlete to diagnose pulmonary, cardiac, solid organ, intra-abdominal and eye injuries.

Can we predict poor hemodynamic tolerance of intermittent hemodialysis with echocardiography in intensive care patients?

OBJECTIVES: Tolerance of intermittent hemodialysis is potentially poor for patients hospitalized in the intensive care unit, particularly those in shock. The aim of this study was to determine whether an evaluation of the hemodynamic state by echocardiography before an intermittent hemodialysis session could predict tolerance during the session. METHODS: Before an intermittent hemodialysis session, transesophageal echocardiography was performed on sedated patients, and transthoracic echocardiography was performed on nonsedated patients. Poor tolerance during intermittent hemodialysis was defined by the following criteria: greater than 20% decrease in mean arterial pressure, need for fluid loading (≥500 mL), a 15% increase in catecholamine if the dose was stable before the session or doubling the speed of catecholamine infusion if necessary, arrhythmia, and the necessity to stop the session before its prescribed end. RESULTS: A total of 54 patients were included: 20 (37%) were intubated under controlled mechanical ventilation (group 1) and underwent transesophageal echocardiography; 14 (26%) were intubated under pressure support ventilation (group 2) and underwent transthoracic echocardiography; and 20 (37%) had no ventilation support (group 3). Twenty-four patients (46%) had poor tolerance criteria. A comparison of groups showed no significant difference in tolerance. Similarly, there was no difference with and without ultrafiltration. Increased respiratory variation of the vena cava was not predictive of poor tolerance in groups 1 and 2. In group 3, there was greater variation in patients with poor tolerance. In patients receiving mechanical ventilation, greater respiratory variability of the maximum velocity measured in the pulmonary artery was predictive of poor tolerance. CONCLUSIONS: The hemodynamic profile of patients receiving mechanical ventilation was unable to predict tolerance of an intermittent hemodialysis session. In patients without mechanical ventilation, hypovolemia before the session appeared to be predictive of poor tolerance.

Ultrasonography of jugular vein as a marker of hypovolemia in healthy volunteers.

BACKGROUND: Our aim in this study was to use ultrasonography of internal jugular vein (IJV) instead of visual estimation by eye and to get more precise estimation of central venous pressure at supine position for estimating blood loss in healthy volunteers. METHODS: The values of the sonographic IJV collapse index and corrected IJV longitudinal length (cIJV LL) (vertical height of the jugular vein from the sternal angle of Louis plus 5 cm) were compared before and after blood donation. The correlations between the mean arterial pressure, pulse rate, IJV collapse index, and cIJV LL were analyzed using SPSS version 15.0 (SPSS, Chicago, IL) and G*Power version 3.1.2. (Franz Faul, Universitat Kiel, Germany) was used for power and sample size analysis. RESULTS: A total of 80 volunteers were enrolled in the study. The medians of cIJV LLs before and after blood donation were 6.67 (95% confidence interval [CI], 6.72-7.07) and 5.98 (95% CI, 6.09-6.40), respectively. The medians of IJV collapse indices before and after blood donation were 32.74 (95% CI, 32.73-39.50) and 38.88 (95% CI, 35.54-42.95), respectively. Preliminary results of our study revealed that cIJV LL and IJV collapse index were not well correlated (Spearman ρ correlation coefficient, 0.257; r = 0.128). CONCLUSION: Although, the IJV collapse index was not found to be a useful parameter for evaluation of hypovolemia, cIJV LL is more valuable marker for the detection of blood loss at bedside.

Role of inferior vena cava and right ventricular diameter in assessment of volume status: a comparative study: ultrasound and hypovolemia.

OBJECTIVE: Ultrasonography has been suggested as a useful noninvasive tool for the detection and follow-up for hypovolemia. Two possible sonographic markers as a surrogate for hypovolemia are the diameters of the inferior vena cava (dIVC) and the right ventricle (dRV). The goal of this study was to evaluate IVC and RV diameters and diameter changes in patients treated for hypovolemia and compare these findings with healthy volunteers. METHODS: Fifty healthy volunteers and 50 consecutive hypovolemic patients were enrolled in the study. The dIVC, both during inspiration (IVCi) and expiration (IVCe), was measured in hypovolemic patients both before and after fluid resuscitation, and they were also measured in healthy volunteers during the time they participated in the study. The dIVC, in hypovolemic patients both before and after fluid resuscitation, was measured ultrasonographically by M-mode in the subxiphoid area. The dRV was measured ultrasonographically by B-mode in the third and fourth intercostals spaces. RESULTS: The average diameters of the IVCe, IVCi, and dRV in hypovolemic patients upon arrival were significantly lower compared with healthy volunteers (P = .001). After fluid resuscitation, there was a significant increase in the mean diameters of the IVCe, IVCi, and RV in hypovolemic patients (P = .001). CONCLUSIONS: The results indicate that the dIVC and dRV are consistently low in hypovolemic subjects when compared with euvolemic subjects. Bedside serial measurements of dIVC and dRV could be a useful noninvasive tool for the detection and follow-up of patients with hypovolemia and evaluation of the response to the treatment.

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.

A wireless ultrasound patch detects mild-to-moderate central hypovolemia during lower body negative pressure.

BACKGROUND: We have developed a wireless, wearable Doppler ultrasound system that continuously measures the common carotid artery Doppler pulse. A novel measure from this device, the Doppler shock index, accurately detected moderate-to-severe central blood volume loss in a human hemorrhage model generated by lower body negative pressure. In this analysis, we tested whether the wearable Doppler could identify only mild-to-moderate central blood volume loss. METHODS: Eleven healthy volunteers were recruited and studied in a physiology laboratory at the Mayo Clinic. Each participant underwent a lower body negative protocol in duplicate. Carotid Doppler measures including Doppler shock indices were compared with blood pressure and the shock index for their ability to detect both 10% and 20% reductions in stroke volume. RESULTS: All carotid Doppler measures were better able to detect diminishing stroke volume than either systolic or mean arterial pressure. Falling carotid artery corrected flow time and rising heart rate/corrected flow time (DSI FTc ) were the most sensitive measures for detecting 10% and 20% stroke volume reductions, respectively. The area under the receiver operator curves (AUROCs) for all shock indices was at least 0.86; however, the denominators of the two Doppler shock indices (i.e., the corrected flow time and velocity time integral) had AUROCs ranging between 0.81 and 0.9, while the denominator of the traditional shock index (i.e., systolic blood pressure) had AUROCs between 0.54 and 0.7. CONCLUSION: The wearable Doppler ultrasound was able to continuously measure the common carotid artery Doppler pulse. Carotid Doppler measures were highly sensitive at detecting both 10% and 20% stroke volume reduction. All shock indices performed well in their diagnostic ability to measure mild-to-moderate central volume loss, although the denominators of both Doppler shock indices individually outperformed the denominator of the traditional shock index. LEVEL OF EVIDENCE: Diagnostic test or criteria; Level III.

Internal jugular vein ultrasound for the diagnosis of hypovolemia and hypervolemia in acutely ill adults: a systematic review and meta-analysis.

Accurate volume status assessments allow physicians to rapidly implement therapeutic measures in acutely unwell patients. However, existing bedside diagnostic tools are often unreliable for assessing intravascular volume. We searched PUBMED, EMBASE, CENTRAL, and Web of Science for English language articles without date restrictions on January 20, 2022. Studies reporting the diagnostic accuracy of IJV-US for hypovolemia and/or hypervolemia in an acute care setting were screened for inclusion. We included studies using any method of IJV-US assessment as the index test, compared against any reference standard. We fitted hierarchical summary receiver operating characteristic (HSROC) models for meta-analysis of diagnostic test accuracy, separately for hypovolemia and hypervolemia. Two reviewers independently extracted data and assessed risk of bias using QUADAS-2. We assessed certainty of evidence using the GRADE approach. A total of 26 studies were included, of which 19 studies (956 patients) examined IJV-US for hypovolemia and 13 studies (672 patients) examined IJV-US for hypervolemia. For the diagnosis of hypovolemia, IJV-US had a pooled sensitivity of 0.82 (95% CI 0.76 to 0.87; moderate-certainty evidence) and specificity of 0.82 (95% CI 0.73 to 0.88; moderate-certainty evidence). Measurement of IJV collapsibility indices had higher diagnostic accuracy (sensitivity 0.85, 95% CI 0.80 to 0.89; specificity 0.78, 95% CI 0.64 to 0.88) than static IJV indices (sensitivity 0.73, 95% CI 0.60 to 0.82; specificity 0.70, 95% CI 0.48 to 0.86). For the diagnosis of hypervolemia, IJV-US had a pooled sensitivity of 0.84 (95% CI 0.70 to 0.92; moderate-certainty evidence) and specificity of 0.70 (95% CI 0.55 to 0.82; very low-certainty evidence). IJV-US has moderate sensitivity and specificity for the diagnosis of hypervolemia and hypovolemia. Randomized controlled trials are needed to determine the role of IJV-US for guiding therapeutic interventions aimed at optimizing volume status.

Reliability of Pre-Induction Inferior Vena Cava Assessment with Ultrasound for the Prediction of Post-Induction Hypotension in Neurosurgical Patients Undergoing Intracranial Surgery.

Background: Hypotension is one of the most common complications following induction of general anesthesia. Preemptive diagnosis and correcting the hypovolemic status can reduce the incidence of post-induction hypotension. However, an association between preoperative volume status and severity of post-induction hypotension has not been established in neurosurgical patients. We hypothesized that preoperative ultrasonographic assessment of intravascular volume status can be used to predict post-induction hypotension in neurosurgical patients. Our study objective was to establish the relationship between pre-induction maximum inferior vena cava (IVC) diameter, collapsibility index (CI), and post-induction reduction in mean arterial blood pressure in neurosurgical patients. Materials and Methods: A prospective observational study was conducted including 100 patients undergoing elective intracranial surgeries. IVC assessment was done before induction of general anesthesia. Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff values of maximum and minimum IVC diameter (IVCDmax and IVCDmin, respectively) and CI for prediction of hypotension. Results: Post-induction hypotension was observed in 41% patients. Patients with small IVCDmax and higher CI% developed hypotension. The areas under the ROC curve (AUCs) were 0.64 (0.53-0.75) for IVCDmax and 0.69 (0.59-0.80) for IVCDmin. The optimal cutoff values were1.38 cm for IVCDmax and 0.94 cm for IVCDmin. The AUC for CI was 0.65 (0.54-0.77) and the optimal cutoff value was 37.5%. Conclusion: Pre-induction IVC assessment with ultrasound is a reliable method to predict post-induction hypotension resulting from hypovolemia in neurosurgical patients.