Hypovolemic shock evaluated by sonographic measurement of the inferior vena cava during resuscitation in trauma patients

Value of inferior vena cava diameter and inferior vena cava collapse index in the evaluation of peripartum volume: A prospective cohort study

OBJECTIVE

The maternal intravascular volume status assessed during and after gestation is valuable but challenging due to the influence of the substantial adaptive cardiovascular changes during pregnancy. The present study aimed to investigate the changes in the size of inferior vena cava (IVC) diameter and collapse index (IVC-CI) during perinatal delivery and whether it is affected by the change in intravascular volume during delivery.

STUDY DESIGN

A total of 31 full-term, singleton, and cephalic delivery women delivered by vagina with an estimated blood loss of >500 mL measured longitudinally between September 2019 and September 2020 in the Department of Obstetrics and Gynecology of The Third Hospital in China. The end-expiratory (IVCe) and end-inspiratory (IVCi) diameters of the inferior vena cava were measured at the first, second, and third stages of labor (T1, T2, and T3, respectively) and postpartum haemorrhage ≥500 mL (T4 and after rapid rehydration 500 mL (T5). The collapse index of IVC was calculated, and blood pressure and heart rate were measured.

RESULTS

IVCe and IVC-CI changed significantly in a volume-dependent manner during the perinatal period (T1-T5; P < 0.05). IVCe narrowed significantly with volume reduction (after postpartum hemorrhage) and widened significantly with volume increase (after volume resuscitation). IVC-CI increases significantly with decreased capacity and decreases significantly with increased capacity.

CONCLUSION

The width and collapse index of IVC reflect the circulatory volume changes during the parturient's perinatal period with postpartum hemorrhage.

Evaluation of caudal vena cava size using computed tomography in dogs under general anesthesia

This study investigated the association between caudal vena cava (CVC) size and circulatory dynamics in dogs using computed tomography (CT) under general anesthesia. The subjects were 104 dogs who had undergone CT under general anesthesia in the past. The ratio of short diameter of the CVC to aortic diameter (CVC_S/Ao) and the ratio of long to short diameter of the CVC (CVC_L/CVC_S) in the thorax and abdomen, respectively, were calculated using factors such as mean blood pressure (MBP), shock index (SI), anemia, hypoproteinemia, presence of intra-abdominal mass, and cardiac disease. There was a significant but negligible negative correlation between CVC_S/Ao and MBP. In contrast, no significant correlation was found between CVC size and SI. The low MBP group had significantly higher CVC_S/Ao of the thorax than the normal MBP group. The group with intra-abdominal mass had significantly lower CVC_S/Ao of the abdomen than the group without intra-abdominal mass. The group with cardiac disease had significantly lower CVC_L/CVC_S of the thorax than the group without cardiac disease. In multiple regression analysis, low MBP, cardiac disease, intra-abdominal mass, and anemia were significant factors for CVC_S/Ao of the thorax, CVC_L/CVC_S of the thorax, CVC_S/Ao of the abdomen, and CVC_L/CVC_S of the abdomen, respectively. In conclusion, CVC size assessment using CT in dogs under general anesthesia is influenced by various factors.

Inferior vena cava ultrasonography in the assessment of intravascular volume status and fluid responsiveness in the emergency department and intensive care unit: A critical analysis review

Rapid evaluation of intravascular volume status is vital; either excessive or limited fluid administration may result in adverse patient outcomes. In this narrative review, critical analysis of pertinent diagnostic accuracy studies is developed to delineate the role of inferior vena cava ultrasound measurements in the assessment of both intravascular volume status and fluid responsiveness in the emergency department and intensive care unit. In addition, limitations, and technical considerations of inferior vena cava ultrasound measurements as well as directions for future research are thoroughly discussed.

The role of mitral annular plane systolic excursion in prediction of acute blood loss in healthy voluntary blood donors

Aim

The aim of this study is to compare the diameter of the inferior vena cava with mitral annular plane systolic excursion measurement in order to determine the volume loss before and after blood donation in healthy volunteers.

Material and methods

The study was a single-center, prospective, cross-sectional study which included 46 healthy blood donors donating in a tertiary care hospital's blood bank. The inclusion criteria for the study were: volunteers aged 18-65 years, over 50 kg in weight, who met blood donation criteria, with hemoglobin values of >13.5 g/dL for males and >12.5 g/dL for females. After obtaining written consent, the systolic, diastolic, and mean arterial blood pressure along with the pulse rate of the donors were measured in standing and lying positions by the attending physician. Next, inferior vena cava and mitral annular plane systolic excursion measurements were made both pre and post blood donation.

Results

The decrease in both inferior vena cava diameter and mitral annular plane systolic excursion values measured pre and post blood donation was found to be statistically significant (p <0.05). There was no difference between the other variables pre and post blood donation.

Conclusions

Our study revealed that decreased inferior vena cava and mitral annular plane systolic excursion values correlated in determining blood loss post blood donation. Mitral annular plane systolic excursion may be useful to predict blood loss in the early stages of hemorrhagic shock.

Echocardiography in a critical care unit: A contemporary review

INTRODUCTION

Echocardiography is a rapid, noninvasive, and complete cardiac assessment tool for patients with hemodynamic instability. This review provides an overview of the evidence for current practices in critical care units (CCUs), incorporating the use of echocardiography in different etiologies of shock.

AREAS COVERED

: Relevant articles were extracted after searching on databases by two reviewers and incorporated in this review in a narrative style.

EXPERT OPINION

: In an acute scenario, a basic echocardiographic study yields prompt diagnosis, allowing for the initiation of treatment. The most common pathologies in shocked patients are identified promptly using two-dimensional (2D) and M-mode echocardiography. A more comprehensive assessment can follow after patients have been stabilized. There are four types of shock: (i) cardiogenic shock, (ii) hypovolemic shock, (iii) obstructive shock, and (iv) septic shock. All of them can be readily identified by echocardiography. As echocardiography is increasingly being used in an intensive care setting, its applications and evidence base should be expanded by randomized controlled trials to demonstrate patient outcomes in critical care.

Can Inferior Vena Cava Diameter and Collapsibility Index Be a Predictor in Detecting Preoperative Intravascular Volume Change in Pediatric Patients?

Background: Inferior vena cava (IVC) ultrasound measurement is a reliable indicator used in the assessment of intravascular volume status. The aim of this study was to evaluate intravascular volume changes in pediatric patients by measuring the IVC diameter and collapsibility index (CI) in children whose oral feeding was restricted preoperatively. Material and Methods: From May 2018 to October 2018, a total of 55 pediatric patients who were scheduled for surgery were included in this prospective, observational, cohort study. Fasting and satiety IVC diameters and CIs of patients were determined by ultrasonographic evaluation twice: in the preoperative preliminary evaluation, when the patients were satiated, and before surgery, during a fasting period of 6–8 hours. Ultra-sonographic data were recorded and compared between fasting and satiety periods. Results: In the grey scale (B-mode), mean IVC diameter was significantly higher when the patients were satiated, compared to the measurements made just before surgery during the fasting period. In the M-mode, the mean IVC diameter was significantly higher only during the inspiratory phase when the patients were satiated, while during the expiratory phase it was detected to be statistically similar. Mean CI was significantly higher in the immediate preoperative period, compared to the assessment made when satiated. Conclusion: Preoperative ultrasound IVC diameter and CI measurement can be a practical and useful method for evaluating preoperative intravascular volume in children.

Assessment of Volume Status and Fluid Responsiveness in Small Animals

Intravenous fluids are an essential component of shock management in human and veterinary emergency and critical care to increase cardiac output and improve tissue perfusion. Unfortunately, there are very few evidence-based guidelines to help direct fluid therapy in the clinical setting. Giving insufficient fluids and/or administering fluids too slowly to hypotensive patients with hypovolemia can contribute to continued hypoperfusion and increased morbidity and mortality. Similarly, giving excessive fluids to a volume unresponsive patient can contribute to volume overload and can equally increase morbidity and mortality. Therefore, assessing a patient's volume status and fluid responsiveness, and monitoring patient's response to fluid administration is critical in maintaining the balance between meeting a patient's fluid needs vs. contributing to complications of volume overload. This article will focus on the physiology behind fluid responsiveness and the methodologies used to estimate volume status and fluid responsiveness in the clinical setting.

Randomized Controlled Trial of Ultrasound-guided Fluid Resuscitation of Sepsis-Induced Hypoperfusion and Septic Shock

Introduction

The ultrasound measurement of inferior vena cava (IVC) diameter change during respiratory phase to guide fluid resuscitation in shock patients is widely performed, but the benefit on reducing the mortality of sepsis patients is questionable. The study objective was to evaluate the 30-day mortality rate of patients with sepsis-induced tissue hypoperfusion (SITH) and septic shock (SS) treated with ultrasound-guided fluid management (UGFM) using ultrasonographic change of the IVC diameter during respiration compared with those treated with the usual-care strategy.

Methods

This was a randomized controlled trial conducted in an urban, university-affiliated tertiary-care hospital. Adult patients with SITH/SS were randomized to receive treatment with UGFM using respiratory change of the IVC (UGFM strategy) or with the usual-care strategy during the first six hours after emergency department (ED) arrival. We compared the 30-day mortality rate and other clinical outcomes between the two groups.

Results

A total of 202 patients were enrolled, 101 in each group (UGFM vs usual-care strategy) for intention-to-treat analysis. There was no significant difference in 30-day overall mortality between the two groups (18.8% and 19.8% in the usual-care and UGFM strategy, respectively; p > 0.05 by log rank test). Neither was there a difference in six-hour lactate clearance, a change in the sequential organ failure assessment score, or length of hospital stay. However, the cumulative fluid amount given in 24 hours was significantly lower in the UGFM arm.

Conclusion

In our ED setting, the use of respiratory change of IVC diameter determined by point-of-care ultrasound to guide initial fluid resuscitation in SITH/SS ED patients did not improve the 30-day survival probability or other clinical parameters compared to the usual-care strategy. However, the IVC ultrasound-guided resuscitation was associated with less amount of fluid used.

Flat Inferior Vena Cava: Indicator of Poor Prognosis in Trauma and Acute Care Surgery Patients

Flat inferior vena cava (IVC) on ultrasound examination has been shown to correlate with hypovolemic status. We hypothesize that a flat IVC on limited echocardiogram (LTTE) performed in the emergency room (ER) correlates with poor prognosis in acutely ill surgical patients. We conducted a retrospective review of all patients undergoing LTTE in the ER from September 2010 until June 2011. IVC diameter was estimated by subxiphoid window. Flat IVC was defined as diameter less than 2 cm. Fat IVC was defined as diameter greater than 2 cm. Need for intensive care unit admission, blood transfusion requirement, mortality, and need for emergent operation between patients with flat versus Fat IVC were compared. One hundred one hypotensive patients had LTTE performed in the ER. Average age was 38 years. Admission diagnosis was blunt trauma (n = 80), penetrating trauma (n = 13), acute care surgery pathology (n = 7), and burn (n = 1). Seventy-four patients had flat IVC on initial LTTE. Compared with those with fat IVC, flat patients were found have higher rates of intensive care unit admission (51.3 vs 14.8%; P = 0.001), blood transfusion requirement (12.2 vs 3.7%), and mortality (13.5 vs 3.7%). This population also underwent emergent surgery on hospital Day 1 more often (16.2 vs 0%; P = 0.033). Initial flat IVC on LTTE is an indicator of hypovolemia and a predictor of poor outcome.

Age-Dependent Association of Occult Hypoperfusion and Outcomes in Trauma

BACKGROUND

Occult hypoperfusion (OH), or global hypoperfusion with normal vital signs, is a risk factor for poor outcomes in elderly trauma patients. We hypothesized that OH is associated with worse outcomes than shock in both young and elderly trauma patients.

METHODS

We conducted a single-center cohort study of adult (16 years or older) trauma patients from 2016 to 2018 with base excess measured on arrival. Perfusion states were defined as shock if heart rate was >120 beats/min or systolic blood pressure was <90 mmHg; OH if base excess was < -2 mmol/L, heart rate was <120 beats/min, and systolic blood pressure was >90 mmHg; and normal for all others. Patients were stratified as young (younger than 55 years) or elderly (55 years or older). Bayesian regression was used to assess the relationship between arrival perfusion state and mortality or serious complication.

RESULTS

Of 3,126 included patients, 808 were elderly. Rates of shock (33% and 31%) and OH (25% and 23%) were similar in young and elderly patients, respectively. OH on arrival was associated with higher odds of mortality or serious complication than normal perfusion, regardless of age group. Compared with shock, OH was associated with an odds ratio of 1.21 (95% CI, 0.97 to 1.52, posterior probability 96%) for poor outcomes in elderly patients and an odds ratio of 0.52 (95% CI, 0.42 to 0.65, posterior probability <1%) for poor outcomes in younger patients. Findings were similar on sensitivity analysis, excluding shock patients with base excess ≥ -2 mmol/L.

CONCLUSIONS

In elderly but not younger patients, OH is associated with worse outcomes than shock. Although shock parameters might need to be redefined in elderly patients, more attention is necessary for the diagnosis and treatment of all hypoperfused states in this age group.

Caval Aortic Index: A Novel Tool for Fluid Assessment in Obstetric Emergencies

BACKGROUND

Uncorrected maternal hypotension occurring during obstetric emergencies may result in maternal and fetal morbidity. Fluid status of the pregnant mother is a major variable which affects the maternal hemodynamics during patient management, and there is no objective assessment tool for the same. A relatively new sonographic parameter, the inferior vena cava aorta (IVC/Ao) diameter index or caval aortic index, showed promise in this regard, and its application was studied in obstetric patients.

METHODOLOGY

A prospective analytical study was conducted involving 50 pregnant and 50 nonpregnant women of reproductive age group. Using both subxiphoid and transhepatic views, their normal fasting caval aortic indices were determined from the ratio of mean IVC diameter to the mean aortic diameter. Descriptive and inferential statistical analyses were carried out accordingly.

RESULTS

Normal IVC/Ao diameter index for nonpregnant healthy women of reproductive age was 1.11 ± 0.29 in the subxiphoid view and 1.21 ± 0.33 in the transhepatic view. The difference between the two views was not statistically significant. IVC/Ao diameter index for a normal term pregnant woman was 1.03 ± 0.26, and term pregnancy does not significantly cause variation in the index.

CONCLUSIONS

Caval aortic index is a useful noninvasive tool to assess volume status and guide fluid management in pregnant women presenting to the emergency department, and the transhepatic view is comparable to the traditional subxiphoid view for the measurement of the same.

Inferior Vena Cava Volume Is an Independent Predictor of Massive Transfusion in Patients With Trauma

OBJECTIVES

Early adequate resuscitation of patients with trauma is crucial in preventing shock and early mortality. Thus, we aimed to determine the performance of the inferior vena cava (IVC) volume and other risk factors and scores in predicting massive transfusion and mortality.

METHODS

We included all patients with trauma who underwent computed tomography (CT) scan of the torso, which included the abdominal area, in our emergency department (ED) from January 2014 to January 2017. We calculated the 3-dimensional IVC volume from the left renal vein to the IVC bifurcation. The primary outcome was the performance of IVC volume in predicting massive transfusion, and the secondary outcome was the performance of IVC volume in predicting 24-hour and 30-day in-hospital mortality.

RESULTS

Among the 236 patients with trauma, 7.6% received massive transfusions. The IVC volume and revised trauma score (RTS) were independent predictors of massive transfusion (adjusted odds ratio [OR]: 0.79 vs 1.86, 95% confidence interval [CI], 0.71-0.89 vs 1.4-2.47, respectively). Both parameters showed the good area under the curve (AUC) for the prediction of massive transfusion (adjusted AUC: 0.83 and 0.82, 95% CI, 0.74-0.92 vs 0.72-0.93, respectively). Patients with a large IVC volume (fourth quartile) were less likely to receive massive transfusion than those with a small IVC volume (first quartile, ≥28.29 mL: 0% vs <15.08 mL: 20.3%, OR: 0.13, 95% CI, 0.03-0.66).

CONCLUSIONS

The volume of IVC measured on CT scan and RTS are independent predictors of massive transfusion in patients with trauma in the ED.

Ultrasound as First Line Step in Anaemia Diagnostics

This review covers the role of ultrasonography as an essential non-invasive diagnostic approach when facing patients with anaemia, a common clinical problem. Abdomen ultrasound is well recognised as a first-line examination in the setting of blood loss, both acute and chronic. Less is clear about the additional opportunities, given by ultrasound in anaemia, due to the many other possible causes. Here we provide information on the utility of ultrasound in different contexts and a practical guide for clinicians facing anaemic patients.

A comparison of noninvasive methods for early detection of hemorrhage: Inferior vena cava ultrasonography and spectrophotometric hemoglobin levels

OBJECTIVES

Blood hemoglobin concentration measurements using a spectrophotometric method (SpHb), and inferior vena cava ultrasonography (IVC-US) are noninvasive methods used to follow-up hemorrhages. We compared their efficacy using voluntary blood donation as a model of moderate (approx. 500 mL) blood loss.

METHODS

In this prospective observational study enrolling blood-donor volunteers (BD) and matched controls, we recorded SpHb, IVC diameters, and vital signs. Changes in variables from baseline were compared between BD and controls using the paired t test and Wilcoxon signed rank test.

RESULTS

We included 118 subjects in the BD group and 95 healthy subjects in the control group. Changes in IVC maximum diameter, IVC minimum diameter, pulse rate, mean arterial pressure, pulse pressure, and shock index, but not in other variables, were significantly different in the BD and the control group (P < 0.05). IVCmax ≥1.1 mm yielded a 74% sensitivity and 77% specificity (PPV 79.8%, NPV 70.2%) in detecting early hemorrhage. With these cutoff values, IVCmax or PR reached a 90% sensitivity, while IVCmin and PR reached 98% specificity.

CONCLUSIONS

IVC ultrasound may be superior to SpHb in predicting blood loss and may be useful in addition to vital signs for its follow-up.

A Morphometric Model for Endovascular Occlusion of The Retrohepatic Vena Cava in Pediatric Trauma

BACKGROUND

The resuscitative endovascular balloon occlusion of the aorta (REBOA) device has been adapted for inferior vena cava (IVC) use in both animal models and adult case reports. The aim of this study is to examine the feasibility for use of the REBOA device for pediatric IVC injuries and create a potential framework for implementation.

MATERIALS AND METHODS

A simulated venous system was designed with modeled IVC components based on 290 abdominal computed tomography scans of pediatric trauma patients. These patients were randomly selected to represent the ten Broselow categories. These IVC segments were selected to represent the posthepatic and prehepatic diameters for the five largest Broselow categories. A closed circulatory model was created with steady-state flow designed to model the venous system. The REBOA device was inserted into the system with the balloon in the IVC segment. Pressure monitors were placed distally and in the closed system, replicating the capacitance of the venous system. A flow meter was placed distally to the segment and balloon. Flow and pressure readings were recorded as the REBOA device was inflated and total occlusion was achieved.

RESULTS

Suprahepatic IVC diameters ranged from 1.14 to 2.71 cm, while infrahepatic IVC diameters ranged from 0.76 to 2.39 cm. There was significant overlap in the measurements of the IVC, allowing five modeled segments to represent ten different IVCs. The venous model demonstrated a significant delay between balloon inflation and vessel occlusion. Approximately 80%-90% of the REBOA inflation volume results in approximately an initial 10% reduction in flow. Flow was completely obstructed which corresponded with a small increase in pressure difference between the proximal and distal pressure monitors, reflecting the capacitance in the venous system with inflation.

CONCLUSIONS

Pediatric IVC injuries with significant hemorrhage should be amenable to endovascular occlusion as an adjunct to resuscitation and operative management.

Inferior vena cava, abdominal aorta, and IVC-to-aorta ratio in healthy Caucasian children: Ultrasound Z-scores according to BSA and age

The pediatric ultrasound measurement of the inferior vena cava (IVC) and aorta (AO) with the study of the collapsibility index (CI) and of IVC-to-AO ratio (IVC/AO) can provide clinicians in the acute care setting with information on abnormal volume status but one of the major limitations is a lack of reference normal values by body surface area (BSA) and age. The aim of this study was to provide reference ranges for the sonographic measurement of IVC, AO, and IVC/AO ratio in healthy Caucasian Italian children.

METHODS

We enrolled prospectively 516 healthy Caucasian Italian children aged between 1 month and 16 years. Echocardiographic IVC and AO diameters were collected and presented separately for children aged ≤1 year and for children aged over 1 year. For children >1 year we categorized subjects into 3 years classes. CI and IVC/AO for the systolic aortic diameter were then calculated. For children over 1 year, age reference ranges were age-related or BSA-related; for children of ≤1 year, reference ranges were determined with their 90% confidence intervals regardless of age and of BSA.

RESULTS

Tables and charts with reference ranges for all the echocardiographic measurements are presented for children aged >1 year according to age and BSA. The equations to obtain percentile and Z-score for each echocardiographic measurement are provided. The reference ranges for children aged ≤1 year are shown considering the small 90% confidence intervals for upper and lower limits. CI was 30% (SD 17%) in children >1 year and 36% (SD 16%) in children <1 year. IVC/AOs showed age-dependent values from 0.83 (SD 0.20) age <1 year to 1.22 (SD 0.31) in older subjects.

CONCLUSIONS

We report reliable reference ranges for echocardiographic measurement of IVC, AO, CI, and IVC/AO for a Caucasian Italian healthy pediatric population.

Focused Cardiac Ultrasonography: Current Applications and Future Directions

Focused cardiac ultrasonography is performed by clinicians at the bedside and is used in time-sensitive scenarios to evaluate a patient's cardiovascular status when comprehensive echocardiography is not immediately available. This simplified cardiac ultrasonography is often performed by noncardiologists using small, portable devices to augment the physical examination, triage patients, and direct management in both critical care and outpatient settings. However, as the use of focused cardiac ultrasonography continues to expand, careful consideration is required regarding training, scope of practice, impact on patient outcomes, and medicolegal implications. In this review, we examine some of the challenges with rapid uptake of this technique and explore the benefits and potential risk of focused cardiac ultrasonography. We propose possible mechanisms for cross-specialty collaboration, quality improvement, and oversight.

Noninvasive estimation of intravascular volume status in cirrhosis by dynamic size and collapsibility indices of the inferior vena cava using bedside echocardiography

Background and Aim

Echocardiographic assessment of the inferior vena cava diameter (IVCD) and collapsibility index (IVCCI) is a noninvasive estimate of intravascular volume status (IVS) but requires validation for cirrhosis. We evaluated IVC dynamics in cirrhosis and correlated it with conventional tools such as central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), and right atrial pressure (RAP).

Methods

A total of 673 consecutive cirrhotic patients were screened by echocardiography, and 125 patients underwent right heart catheterization with recording of hepatic venous pressure gradient (HVPG), RAP, pulmonary artery (PA) pressure, and PCWP. CVP data were available for 80 (64%) patients, and finally, 76 patients (84% male, 50% ethanol related, mean age 52.1 years, 57.8% with ascites) with complete data were enrolled.

Results

The mean CVP measured was 12.8 ± 4.8 mmHg, and IVCCI was 29.5 ± 10.9%. The IVCD ranged from 0.97 to 2.26 cm and from 0.76 to 1.84 cm during expiration and inspiration, respectively, with a mean of 1.8 ± 0.9 cm. The mean IVCD correlated with RAP (r = 0.633, P = 0.043) but not with HVPG (r = 0.344, P = 0.755), PCWP (r = 0.562, P = 0.072), or PA pressure (r = 0.563, P = 0.588). A negative linear correlation was observed between the CVP and the IVCCI (r = −0.827, P = 0.023) in all patients and substratified for those with (r = −0.748, P = 0.039) and without ascites (r = −0.761, P = 0.047). A positive correlation was observed between CVP and IVCD_max (r = 0.671, P = 0.037) and IVCD_min (r = 0.612, P = 0.040).

Conclusions

IVCD and collapsibility index provides noninvasive IVS assessment, independent of HVPG or ascites, with the potential for calculating fluid requirements in cirrhosis.

The inferior vena cava diameter is a useful ultrasound finding for predicting postpartum blood loss

Purpose: To assess whether the ultrasonographic measurement of the inferior vena cava (IVC) diameter in postpartum women is a useful parameter in evaluating the actual blood loss during delivery due to massive postpartum hemorrhage. Materials and methods: In postpartum women with blood loss ≥500 g, abdominal ultrasonography was performed 1 hour after delivery. The IVC diameter was measured during inspiration (IVCi) and expiration (IVCe). The maternal heart rate, blood pressure, and shock index (heart rate/systolic blood pressure) were also measured. The predictive value of these parameters for severe anemia (hemoglobin <7.0 g/dL) a day after delivery was evaluated via receiver operating characteristic (ROC) analyses. Results: Seven patients with severe anemia and 77 controls were included in the analysis. The area under the curve (AUC) for IVCi (0.905) and IVCe (0.926) was higher than that for the shock index (0.890), heart rate (0.874), or systolic blood pressure (0.752). Among the examined parameters, the best sensitivity was achieved by IVCe and systolic blood pressure (71.4%). Conclusions: The ultrasonographic measurement of the IVC diameter was found to be the most useful parameter in evaluating the actual maternal blood loss after delivery.

Normative Data for IVC Diameter and its Correlation with the Somatic Parameters in Healthy Indian Children

OBJECTIVE

To determine the normative data for inferior vena cava (IVC) diameter in children and its correlation with various somatic parameters like height, weight and body surface area in Indian children. Readily available baseline data of IVC diameter in normal children shall be of great help in rapid assessment of variations in sick children.

METHODS

Total 475 healthy children aged one month to 12 y visiting out patient clinics (OPD's) were enrolled in this study. Weight, height and body surface area were calculated at the time of examination. The maximum and minimum diameters of IVC were measured during the expiratory and inspiratory phase of the respiratory cycle respectively using M mode ultrasonography. Collapsibility Index was also calculated for each subject by measuring difference between the maximum (expiratory) and minimum (inspiratory) IVC diameters divided by the maximum diameter.

RESULTS

The mean age of study subjects was 4.72 ± 3.72 y. Out of 475 subjects, 285 (60%) were boys and 190 (40%) were girls. Mean weight for age (%) of subjects was 89.18 ± 13.26%. Correlation was studied between physical parameters and IVC diameter which revealed a positive correlation of age, height and weight with both maximum and minimum IVC diameter. Regression analysis was also performed to derive the equations for maximum and minimum diameters of children from 1 y to 12 y.

CONCLUSIONS

This study provides reference values of IVC diameters for Indian children of different age groups.

Accuracy of Ultrasonographic Measurements of Inferior Vena Cava to Determine Fluid Responsiveness: A Systematic Review and Meta-Analysis

OBJECTIVE

Fluid responsiveness is the ability to increase the cardiac output in response to a fluid challenge. Only about 50% of patients receiving fluid resuscitation for acute circulatory failure increase their stroke volume, but the other 50% may worsen their outcome. Therefore, predicting fluid responsiveness is needed. In this purpose, in recent years, the assessment of the inferior vena cava (IVC) through ultrasound (US) has become very popular. The aim of our work was to systematically review all the previously published studies assessing the accuracy of the diameter of IVC or its respiratory variations measured through US in predicting fluid responsiveness.

DATA SOURCES

We searched in the MEDLINE (PubMed), Embase, Web of Science databases for all relevant articles from inception to September 2017.

STUDY SELECTION

Included articles specifically addressed the accuracy of IVC diameter or its respiratory variations assessed by US in predicting the fluid responsiveness in critically ill ventilated or not, adult or pediatric patients.

DATA EXTRACTION

We included 26 studies that investigated the role of the caval index (IVC collapsibility or distensibility) and 5 studies on IVC diameter.

DATA SYNTHESIS

We conducted a meta-analysis for caval index with 20 studies: The pooled area under the curve, logarithmic diagnostic odds ratio, sensitivity, and specificity were 0.71 (95% confidence interval [CI]: 0.46-0.83), 2.02 (95% CI: 1.29-2.89), 0.71 (95% CI: 0.62-0.80), and 0.75 (95% CI: 0.64-0.85), respectively.

CONCLUSION

An extreme heterogeneity of included studies was highlighted. Ultrasound evaluation of the diameter of the IVC and its respiratory variations does not seem to be a reliable method to predict fluid responsiveness.

Comparison of Hemodynamic Monitoring between Transesophageal Doppler and Ultrasonography-Guided Inferior Vena Cava Distensibility in Supine versus Prone Position: A Pilot Study

Introduction

Lung-protective ventilation strategy and prone positioning are the strategies practiced to manage patients suffering from acute respiratory distress syndrome (ARDS). Inferior Vena Cava Distensibility (dIVC) Index has been used for predicting fluid responsiveness (FR) in supine position. We conducted this study to observe the utility of dIVC in prone position in ARDS patients and compare it with esophageal Doppler (ED) parameters.

Materials and Methods

After ethical clearance, a prospective observational pilot study was conducted in a 12-bedded tertiary care hospital. Adult ARDS patients who were treated with prone ventilation were included. Informed consent was taken from the relatives. IVC was visualized through right lateral approach both in supine and prone positions. We compared IVC distensibility and ED parameters, first in 45° head up and then in prone. FR was defined as an increase in the stroke volume of ≥15% as measured by ED. The patients with dIVC >18% were assumed to be fluid responsive. Statistical analysis was done using SPSS software version 20.

Results

Twenty-five patients met the inclusion criteria. ARDS was (mean P/F ratio 116.64 ± 44.76) mostly due to pulmonary etiology. Out of 25 patients, 10 patients were fluid responsive based on dIVC (cutoff >18%) in supine position. When compared to ED values after passive leg raising, dIVC had a sensitivity and specificity of 77.78% and 81.25%, respectively, in predicting FR with a moderate-to-absolute agreement between the two methods. IVC distensibility showed statistically significant negative correlation with corrected flow time (FTc) values both in supine and in prone positions.

Conclusion

IVC variability can be observed in acute respiratory distress syndrome patients in prone position. Inferior Vena Cava Distensibility correlates with flow time in both the positions.

Initial inferior vena cava diameter predicts massive transfusion requirements in blunt trauma patients: A retrospective cohort study

OBJECTIVES

The inferior vena cava (IVC) diameter is associated with shock and increased mortality in trauma patients. However, there are no reports examining the association between the IVC diameter and massive transfusion (MT) requirements in trauma patients. The aim of this study was to evaluate the association between IVC diameter and MT requirements in patients with blunt trauma.

METHODS

We retrospectively reviewed all patients who were consecutively hospitalized with blunt trauma (Injury Severity Score [ISS] ≥16) between from November 1, 2011 to March 30, 2016. Univariate and multivariate analyzes were performed to identify the independent predictors of MT (defined as >10units of red cell concentrate transfusions within 24h of admission). Receiver operating characteristic curve and the area under the curve (AUC) were estimated.

RESULTS

Of the 222 patients included in this study, MT occurred in 22.5% patients. On multiple regression analysis, IVC diameter [Odds ratio (OR), 0.88; 95% confidence interval (CI), 0.80-0.96; p<0.01], fibrin degradation product (FDP; OR, 1.01; 95% CI, 1.00-1.01; p<0.01), and fibrinogen level (OR, 0.99; 95% CI, 0.98-1.00; p<0.01) were strong predictors of MT. IVC diameter demonstrated moderate accuracy (AUC, 0.74; cutoff level, 13.0mm; sensitivity, 67%; specificity, 73%). Combined cutoff levels of FDP <80.5μg/ml, fibrinogen ≥165mg/dl, and IVC diameter ≥13mm could also determine how unnecessary a MT was with 100% accuracy.

CONCLUSIONS

Initial IVC diameter is a predictor of MT in blunt trauma patients.

Inferior Vena Cava Measurement with Ultrasound: What Is the Best View and Best Mode?

Introduction

Intravascular volume status is an important clinical consideration in the management of the critically ill. Point-of-care ultrasonography (POCUS) has gained popularity as a non-invasive means of intravascular volume assessment via examination of the inferior vena cava (IVC). However, there are limited data comparing different acquisition techniques for IVC measurement by POCUS. The goal of this evaluation was to determine the reliability of three IVC acquisition techniques for volume assessment: sub-xiphoid transabdominal long axis (LA), transabdominal short axis (SA), and right lateral transabdominal coronal long axis (CLA) (aka “rescue view”).

Methods

Volunteers were evaluated by three experienced emergency physician sonographers (EP). Gray scale (B-mode) and motion-mode (M-mode) diameters were measured and IVC collapsibility index (IVCCI) calculated for three anatomic views (LA, SA, CLA). For each IVC measurement, we calculated descriptive statistics, intra-class correlation coefficients (ICC), and two-way univariate analyses of variance.

Results

EPs evaluated 39 volunteers, yielding 351 total US measurements. Measurements of the three views had similar means (LA 1.9 ± 0.4cm; SA 1.9 ± 0.4cm; CLA 2.0 ± 0.5cm). For B-Mode, LA had the highest ICC (0.86, 95% CI [0.76–0.92]) while CLA had the poorest ICC (0.74, 95% CI [0.56–0.85]). ICCs for all M-mode IVCCI were low. Significant interaction effects between anatomical view and EP were observed for B-mode and M-mode measurements. Post-hoc analyses revealed difficulty in consistent view acquisition between EPs.

Conclusion

Inter-rater reliability of the IVC by EPs was highest for B-mode LA and poorest for all M-Mode IVC collapsibility indices (IVCCI). These results suggest that B-mode LA holds the most promise to deliver reliable measures of IVC diameter. Future studies may focus on validation in a clinical setting as well as comparison to a reference standard.

A Non-invasive Method for Assessment of Intravascular Fluid Status: Inferior Vena Cava Diameters and Collapsibility Index

Objective:

To evaluate the correlation between central venous pressure (CVP) and inferior vena cava (IVC) diameters measured by ultrasonography (Ultrasound) in critically ill patients.

Methods:

Intubated critically ill patients were enrolled. The CVP values were measured using a U-tube manometer and were compared to the IVC diameters and collapsibility index, which were measured by bedside Ultrasound. Patients younger than 18 years old, who were not intubated, who had an abdominal pressure greater than 12 mmHg, and/or who were admitted for trauma were excluded from the study.

Results:

Eighty three patients with a mean age of 73.6±11.2 years were enrolled. The most common diagnosis was sepsis (21 patients, 25.30%). IVC inspiration measurements were statistically significantly correlated with CVP measurements (p0.05, r: 0.1). IVC collapsibility measurements showed a negative correlation with CVP measurements (p<0.01, r: 0.68).

Conclusions:

There is a strong correlation between CVP and IVC diameters and the collapsibility index. This is a new formula for evaluating CVP, based on our statistical analyses.

The assessment of circulating volume using inferior vena cava collapse index and carotid Doppler velocity time integral in healthy volunteers: a pilot study

BACKGROUND

Assessment of circulating volume and the requirement for fluid replacement are fundamental to resuscitation but remain largely empirical. Passive leg raise (PLR) may determine fluid responders while avoiding potential fluid overload. We hypothesised that inferior vena cava collapse index (IVCCI) and carotid artery blood flow would change predictably in response to PLR, potentially providing a non-invasive tool to assess circulating volume and identifying fluid responsive patients.

METHODS

We conducted a prospective proof of concept pilot study on fasted healthy volunteers. One operator measured IVC diameter during quiet respiration and sniff, and carotid artery flow. Stroke volume (SV) was also measured using suprasternal Doppler. Our primary endpoint was change in IVCCI after PLR. We also studied changes in IVCCI after "sniff", and correlation between carotid artery flow and SV.

RESULTS

Passive leg raise was associated with significant reduction in the mean inferior vena cava collapsibility index from 0.24 to 0.17 (p < 0.01). Mean stroke volume increased from 56.0 to 69.2 mL (p < 0.01). There was no significant change in common carotid artery blood flow. Changes in physiology consequent upon passive leg raise normalised rapidly.

DISCUSSION

Passive leg raise is associated with a decrease of IVCCI and increase in stroke volume. However, the wide range of values observed suggests that factors other than circulating volume predominate in determining the proportion of collapse with respiration.

CONCLUSION

In contrast to other studies, we did not find that carotid blood flow increased with passive leg raise. Rapid normalisation of post-PLR physiology may account for this.

Practical Assessment of Volume Status in Daily Practice

Fluid therapy is considered the cornerstone of treatment for patients suffering from various medical ailments particularly in emergency and critical care situations where hypovolemia commonly occurs. The ability to accurately assess a patient's volume status is critical to the decision making process when synthesizing and implementing a fluid therapy plan. Both extremes, over supplementation or not supplementing enough fluid can be detrimental to the patient. Precisely assessing a patient's blood volume without access to advanced often complicated equipment and monitoring devices is challenging. The aim of this paper is to review the practical means and tools available to aide in estimating a patient's volume status.

Echocardiography in shock management

Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.

In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.

The four core types of shock—cardiogenic, hypovolemic, obstructive, and vasoplegic—can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.

The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock.

Make it SIMPLE: enhanced shock management by focused cardiac ultrasound

BACKGROUND

Shock is a spectrum of circulatory failure that, if not properly managed, would lead to high mortality. Special diagnostic and treatment strategies are essential to save lives. However, clinical and laboratory findings are always non-specific, resulting in clinical dilemmas.

MAIN CONTENT

Focused cardiac ultrasound (FoCUS) has emerged as one of the power tools for clinicians to answer simple clinical questions and guide subsequent management in hypotensive patients. This article will review the development and utility of FoCUS in different types of shock. The sonographic features and ultrasound enhanced management of hypotensive patients by a de novo "SIMPLE" approach will be described. Current evidence on FoCUS will also be reviewed.

CONCLUSION

Focused cardiac ultrasound provides timely and valuable information for the evaluation of shock. It helps to improve the diagnostic accuracy, narrow the possible differential diagnoses, and guide specific management. SIMPLE is an easy-to-remember mnemonic for non-cardiologists or novice clinical sonographers to apply FoCUS and interpret the specific sonographic findings when evaluating patients in shock.

On table POCUS assessment for the IVC following abdominal packing: how I do it

BACKGROUND

Some surgeons may lack proper experience in abdominal packing. Overpacking may directly compress the inferior vena cava (IVC). This reduces the venous return and possibly causes hypotension. Here, a new on table Point-of-Care Ultrasound application that has been recently used to assess the effect of abdominal packing on the IVC diameter is described. Following abdominal packing, a small print convex array probe with low frequency (2-5 MHz) is used to visualize the IVC. Using the B mode, the IVC can be directly evaluated through a hepatic window between the ribs. The ultrasound beam should be vertical to the IVC longitudinal section at its midpoint. The abdominal towels will be in front of the IVC. This will enable us to judge whether there was overpacking on the IVC.

RESULTS

Our method demonstrates that overpacking does not compress the IVC in a patient whose blood pressure has improved. The IVC diameter progressively increases on table and in the ICU with active resuscitation implying that bleeding stopped and the resuscitation was successful. Furthermore, presence of intra-peritoneal fluid can be excluded.

CONCLUSIONS

This new application of ultrasound evaluation of IVC patency after abdominal packing is simple, practical, easily reproducible, and can guide a less experienced surgeon in determining if overpacking of the abdomen is the cause of hypotension. Ultrasound findings should be correlated with the clinical picture to be useful.

Optimizing the value of measuring inferior vena cava diameter in shocked patients

Point-of-care ultrasound has been increasingly used in evaluating shocked patients including the measurement of inferior vena cava (IVC) diameter. Operators should standardize their technique in scanning IVC. Relative changes are more important than absolute numbers. We advise using the longitudinal view (B mode) to evaluate the gross collapsibility, and the M mode to measure the IVC diameter. Combining the collapsibility and diameter size will increase the value of IVC measurement. This approach has been very useful in the resuscitation of shocked patients, monitoring their fluid demands, and predicting recurrence of shock. Pitfalls in measuring IVC diameter include increased intra-thoracic pressure by mechanical ventilation or increased right atrial pressure by pulmonary embolism or heart failure. The IVC diameter is not useful in cases of increased intra-abdominal pressure (abdominal compartment syndrome) or direct pressure on the IVC. The IVC diameter should be combined with focused echocardiography and correlated with the clinical picture as a whole to be useful.

Posttraumatic Resuscitation Affects Stent Graft Sizing in Patients with Blunt Thoracic Aortic Injury

Patients with blunt aortic injury often present to the emergency department in a relatively hypovolemic state. These patients undergo extensive inhospital resuscitation. The effect of posttraumatic resuscitation on aortic diameter has implications for stent graft sizing. The potential utility of repeat aortic imaging after resuscitation remains unclear. A retrospective chart review of all adult patients presenting to a Level I trauma center between the years 2007 and 2013 was performed. Fifty-three patients were identified with a diagnosis of traumatic aortic injury. Of those, 10 had 2 CT scans before aortic repair and were selected as the study population for analysis. After resuscitation, there was a significant increase in aortic diameter both proximal and distal to the aortic injury: proximal aortic diameter increase of 1.97 mm and distal aortic diameter increase of 1.48 mm. This retrospective study shows that after resuscitation, there is a significant increase in proximal and distal aortic diameter. Interval reimaging of the thoracic aorta may be beneficial after adequate stabilization of the patient's other injuries. In certain cases, more appropriate sizing may prevent a device-related complication.

Assessment of volume status and fluid responsiveness in the emergency department: a systematic approach

When treating acutely ill patients in the emergency department (ED), the successful management of a variety of medical conditions, such as sepsis, acute kidney injury, and pancreatitis, is highly dependent on the correct assessment and optimization of a patient's intravascular volume status. Therefore, it is crucial that the ED physician knows and uses available means to assess intravascular volume status to adequately guide fluid therapy. This review focuses on techniques for volume status assessment that are available in the ED including basic clinical and laboratory findings, apparatus-based tests such as sonography and chest x-ray, and functional tests to evaluate fluid responsiveness. Furthermore, we provide an outlook on promising innovative, noninvasive technologies that might be used for advanced hemodynamic monitoring in the ED.

Surgeon-performed bedside ultrasound to assess volume status: a feasibility study

PURPOSE

Rapid assessment of volume status in children is often difficult. The purpose of this study was to evaluate the feasibility of surgeon-performed ultrasound to assess volume status in patients with hypertrophic pyloric stenosis.

METHODS

Ultrasounds were performed on admission and before operation. The diameters of the inferior vena cava (IVC) and aorta (Ao) were measured and IVC/Ao ratios were calculated. Electrolytes were measured on admission and repeated if warranted. Logistic regression was used to associate the clinical outcome, defined as CO2 ≤30 mEq/L, with IVC/Ao ratios. Predictive capacity was estimated from the logistic regression for IVC/Ao ratios. Linear regression was used to estimate associations between CO2 values and IVC/Ao ratios.

RESULTS

Thirty-one patients were enrolled. The IVC/Ao ratio is highly associated with actual CO2 values (P < 0.001) and the clinical outcome (P = 0.004). For every 0.05 unit increase in IVC/Ao ratio, predicted CO2 decreased 1.1 units. For every 0.05 unit increase in the IVC/Ao ratio, the odds of having a CO2 ≤30 mEq/L increased 48% [OR = 1.48, 95% CI (1.13,1.94)]. Predictive capacity is maximized at an IVC/Ao ratio of 0.75 as 83.9 % of subjects were correctly classified and specificity and PPV = 100%.

CONCLUSIONS

Surgeon-performed ultrasound to determine IVC/Ao ratio is feasible. An IVC/Ao ratio of 0.75 predicted adequate resuscitation.

Inferior vena cava collapsibility loses correlation with internal jugular vein collapsibility during increased thoracic or intra-abdominal pressure

PURPOSE

Point-of-care ultrasound evaluates inferior vena cava (IVC) and internal jugular vein (IJV) measurements to estimate intravascular volume status. The reliability of the IVC and IJV collapsibility index during increased thoracic or intra-abdominal pressure remains unclear.

METHODS

Three phases of sonographic scanning were performed: spontaneous breathing phase, increased thoracic pressure phase via positive pressure ventilation (PPV) phase, and increased intra-abdominal pressure (IAP) phase via laparoscopic insufflation to 15 mmHg. IVC measurements were done at 1-2 cm below the diaphragm and IJV measurements were done at the level of the cricoid cartilage during a complete respiratory cycle. Collapsibility index was calculated by (max diameter - min diameter)/max diameter × 100 %. Chi square, t test, correlation procedure (CORR) and Fisher's exact analyses were completed.

RESULTS

A total of 144 scans of the IVC and IJV were completed in 16 patients who underwent laparoscopic surgery. Mean age was 46 ± 15 years, with 75 % female and 69 % African-American. IVC and IJV collapsibility correlated in the setting of spontaneous breathing (r (2) = 0.86, p < 0.01). IVC collapsibility had no correlation with the IJV in the setting of PPV (r (2) = 0.21, p = 0.52) or IAP (r (2) = 0.26, p = 0.42). Maximal IVC diameter was significantly smaller during increased IAP (16.5 mm ± 4.9) compared to spontaneous breathing (20.6 mm ± 4.8, p = 0.04) and PPV (21.8 mm ± 5.6, p = 0.01).

CONCLUSION

IJV and IVC collapsibility correlated during spontaneous breathing but there was no statistically significant correlation during increased thoracic or intra-abdominal pressure. Increased intra-abdominal pressure was associated with a significant smaller maximal IVC diameter and cautions the reliability of IVC diameter in clinical settings that are associated with intra-abdominal hypertension or abdominal compartment syndrome.

International evidence-based recommendations for focused cardiac ultrasound

BACKGROUND

Focused cardiac ultrasound (FoCUS) is a simplified, clinician-performed application of echocardiography that is rapidly expanding in use, especially in emergency and critical care medicine. Performed by appropriately trained clinicians, typically not cardiologists, FoCUS ascertains the essential information needed in critical scenarios for time-sensitive clinical decision making. A need exists for quality evidence-based review and clinical recommendations on its use.

METHODS

The World Interactive Network Focused on Critical UltraSound conducted an international, multispecialty, evidence-based, methodologically rigorous consensus process on FoCUS. Thirty-three experts from 16 countries were involved. A systematic multiple-database, double-track literature search (January 1980 to September 2013) was performed. The Grading of Recommendation, Assessment, Development and Evaluation method was used to determine the quality of available evidence and subsequent development of the recommendations. Evidence-based panel judgment and consensus was collected and analyzed by means of the RAND appropriateness method.

RESULTS

During four conferences (in New Delhi, Milan, Boston, and Barcelona), 108 statements were elaborated and discussed. Face-to-face debates were held in two rounds using the modified Delphi technique. Disagreement occurred for 10 statements. Weak or conditional recommendations were made for two statements and strong or very strong recommendations for 96. These recommendations delineate the nature, applications, technique, potential benefits, clinical integration, education, and certification principles for FoCUS, both for adults and pediatric patients.

CONCLUSIONS

This document presents the results of the first International Conference on FoCUS. For the first time, evidence-based clinical recommendations comprehensively address this branch of point-of-care ultrasound, providing a framework for FoCUS to standardize its application in different clinical settings around the world.

Sonographic inferior vena cava measurements to assess hydration status in college football players during preseason camp

OBJECTIVES

The purpose of this study was to determine whether sonographic measurement of the inferior vena cava (IVC) in college football players during preseason camp is a reliable way to detect and monitor dehydration. Our primary hypothesis was that IVC diameter measurements, the postpractice caval index, and expiratory diameter were significantly related to percent weight loss after a preseason football practice.

METHODS

A prospective cohort sample of Division I intercollegiate football players in preseason training camp was recruited before practice. All football players on the active roster who were at least 18 years of age were eligible to participate in the study. Sonographic IVC measurements were obtained in the long axis using either the subcostal or subxiphoid approach during inspiration and expiration both before and after an approximately 3-hour practice with moderate to high levels of exertion at high ambient temperatures. Player weights were recorded in the locker room before and after practice.

RESULTS

A total of 27 prepractice and postpractice sonographic measurements were obtained. The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice (R(2) = 0.153; P = .042), with the IVC diameter being significantly inversely correlated with percent weight loss; the regression coefficient was -1.07 (95% confidence interval, -2.09 to -0.04). There was no statistically significant relationship between percent weight loss and the postpractice caval index; the regression coefficient was 0.245 (95% confidence interval, -0.10 to 0.59; R(2) = 0.078; P = .16).

CONCLUSIONS

The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice, whereas the caval index was not found to correlate with weight loss.

A simple predictive formula for the blood requirement in patients with high-energy blunt injuries transferred within one hour post-trauma

Aims

To recognize patients who require massive transfusion at the early stage of blunt trauma, we retrospectively investigated patients with high-energy blunt injuries transferred within 1 h post-trauma.

Methods

Between August 2007 and July 2011, 233 trauma patients were: (i) injured by a high-energy blunt mechanism with Injury Severity Score ≥9; (ii) not dead on arrival; (iii) older than 9 years; and (iv) at our center within 1 h after injury. The findings for 113 of those patients were analyzed, including those produced by ultrasonography, computed tomography, and arterial blood gas analyses.

Results

Of 113 patients, 33 underwent massive transfusion (≥6 units) within 8 h of arrival. A logistic regression analysis revealed that an arterial lactate level ≥28 mg/dL (P < 0.001; odds ratio, 105.11; 95% confidence interval, 12.58-2,718.84) and a flat ratio of the inferior vena cava on computed tomography ≥3 (P < 0.001; odds ratio, 32.50; 95% confidence interval, 4.44-714.44) were significant independent predictors for a massive transfusion within 8 h. In a receiver operating curve analysis, the area under the curve of the need for massive transfusion was 0.956, with a sensitivity of 0.94 and a specificity of 0.90. A linear predictive formula for the probability (P) of receiving a massive transfusion was generated as P = 2 × lactate (mg/dL) + 15 × the flat ratio of inferior vena cava - 103. Using another 52 trauma patients, the formula was validated.

Conclusions

An elevated level of arterial lactate and the flat ratio of inferior vena cava were significant predictors for identifying the patients who would require a massive transfusion in the early stage after high-energy blunt trauma.

Optimizing oxygen delivery in the critically ill: assessment of volume responsiveness in the septic patient

BACKGROUND

Assessing volume responsiveness, defined as an increase in cardiac index after infusion of fluids, is important when caring for critically ill patients in septic shock, as both under- and over-resuscitation can worsen outcomes. This review article describes the currently available methods of assessing volume responsiveness for critically ill patients in the emergency department, with a focus on patients in septic shock.

OBJECTIVE

The single-pump model of the circulation utilizing cardiac-filling pressures is reviewed in detail. Additionally, the dual-pump model evaluating cardiopulmonary interactions both invasively and noninvasively will be described.

DISCUSSION

Cardiac filling pressures (central venous pressure and pulmonary artery occlusion pressure) have poor performance characteristics when used to predict volume responsiveness. Cardiopulmonary interaction assessments (inferior vena cava distensibility/collapsibility, systolic pressure variation, pulse pressure variation, stroke volume variation, and aortic flow velocities) have superior test characteristics when measured either invasively or noninvasively.

CONCLUSION

Cardiac filling pressures may be misleading if used to determine volume responsiveness. Assessment of cardiopulmonary interactions has superior performance characteristics, and should be preferentially used for septic shock patients in the emergency department.

The relationship between inferior vena cava diameter measured by bedside ultrasonography and central venous pressure value

Objective: We aimed to present inferior vena cava (IVC) diameter as a guiding method for detection of relationship between IVC diameter measured noninvasively with the help of ultrasonography (USG) and central venous pressure (CVP) and evaluation of patient's intravascular volume status.

Methods: Patients over the age of 18, to whom a central venous catheter was inserted to their subclavian vein or internal jugular vein were included in our study. IVC diameter measurements were recorded in millimeters following measurement by the same clinician with the help of USG both at the end-inspiratory and end-expiratory phase. CVP measurements were viewed on the monitor by means of piezoelectric transducer and recorded in mmHg. SPSS 18.0 package program was used for statistical analysis of data.

Results: Forty five patients were included in the study. The patients had the diagnosis of malignancy (35.6%), sepsis (13.3%), pneumonia, asthma, chronic obstructive pulmonary disease (11.1%). 11 patients (24.4%) required mechanical ventilation while 34 (75.6%) patients had spontaneous respiration. In patients with spontaneous respiration, a significant relationship was found between IVC diameters measured by ultrasonography at the end of expiratory and inspiratory phases and measured CVP values at the same phases (for expiratory p = 0.002, for inspiratory p= 0.001). There was no statistically significant association between IVC diameters measured by ultrasonography at the end of expiration and inspiration and measured CVP values at the same phases in mechanically ventilated patients.

Conclusions: IVC diameter measured by bedside ultrasonography can be used for determination of the intravascular volume status of the patients with spontaneous respiration.

Findings of a randomized controlled trial using limited transthoracic echocardiogram (LTTE) as a hemodynamic monitoring tool in the trauma bay

BACKGROUND

We hypothesize that limited transthoracic echocardiogram (LTTE) is a useful tool to guide therapy during the initial phase of resuscitation in trauma patients.

METHODS

All highest-level alert patients with at least one measurement of systolic blood pressure less than 100 mm Hg, a mean arterial pressure less than 60 mm Hg, and/or a heart rate greater than 120 beats per minute who arrived to the trauma bay (TB) were randomized to have either LTTE performed (LTTEp) or not performed (non-LTTE) as part of their initial evaluation. Images were stored, and results were reported regarding contractility (good vs. poor), fluid status (empty inferior vena cava [hypovolemic] vs. full inferior vena cava [not hypovolemic]), and pericardial effusion (present vs. absent). Time from TB to operating room, intravenous fluid administration, blood product requirement, intensive care unit admission, and mortality were examined in both groups.

RESULTS

A total of 240 patients were randomized. Twenty-five patients were excluded since they died upon arrival to the TB, leaving 215 patients in the study. Ninety-two patients were in the LTTEp group with 123 patients in the non-LTTE group. The LTTEp and non-LTTE groups were similar in age (38 years vs. 38.8 years, p = 0.75), Injury Severity Score (ISS) (19.2 vs. 19.0, p = 0.94), Revised Trauma Score (RTS) (5.5 vs. 6.0, p = 0.09), lactate (4.2 vs. 3.6, p = 0.14), and mechanism of injury (p = 0.44). Strikingly, LTTEp had significantly less intravenous fluid than non-LTTE patients (1.5 L vs. 2.5 L, p < 0.0001), less time from TB to operating room (35.6 minutes vs. 79.1 min, p = 0.0006), higher rate of intensive care unit admission (80.4% vs. 67.2%, p = 0.04), and a lower mortality rate (11% vs. 19.5%, p = 0.09). Mortality differences were particularly evident in the traumatic brain injury patients (14.7% in LTTEp vs. 39.5% in non-LTTE, p = 0.03).

CONCLUSION

LTTE is a useful guide for therapy in hypotensive trauma patients during the early phase of resuscitation.

LEVEL OF EVIDENCE

Therapeutic study, level II.

Initial inferior vena cava diameter on computed tomographic scan independently predicts mortality in severely injured trauma patients

BACKGROUND

In the trauma population, patients with physiologic compromise may present with "normal" vital signs. We hypothesized that the inferior vena cava (IVC) diameter could be used as a surrogate marker for hypovolemic shock and predict mortality in severely injured trauma patients.

METHODS

A retrospective cohort study was performed at a Level I trauma center on 161 severely injured adult (aged ≥ 16 years) trauma patients who were transported from the scene and underwent abdominal computed tomography within 1 hour. Exposure of interest was dichotomously defined as having an infrarenal transverse to anteroposterior IVC ratio of ≥ 1.9 (flat IVC) or <1.9 (not exposed) based on the area under the curve analysis. The primary outcome was in-hospital mortality. Covariates included initial heart rate, systolic blood pressure, bicarbonate, base excess, creatinine, hemoglobin, and Injury Severity Score (ISS). Correlation analysis between IVC ratio and other known markers of hypoperfusion was performed. Logistic regression was used to determine the independent effect of the IVC ratio on mortality.

RESULTS

Of the 161 patients, 30 had a flat IVC. The IVC ratio had a significant (p < 0.05) inverse correlation with initial bicarbonate, hemoglobin, and base excess and a direct correlation with Cr and ISS. After controlling for age, ISS, and presence of severe head injury, patients who had a flat IVC were 8.1 times (95% confidence interval, 1.5-42.9) more likely to die compared with the nonexposed cohort. Importantly, heart rate and systolic blood pressure had no predictive value in this patient population.

CONCLUSION

A flat IVC on initial abdominal computed tomographic scan has a significant correlation with other known markers of shock and is an independent predictor of mortality in severely injured trauma patients. This finding should heighten the awareness of the need for aggressive intervention and potential for physiological decompensation in patients with otherwise "normal" vital signs.

LEVEL OF EVIDENCE

Prognostic study, level III.