Prospective evaluation of intravascular volume status in critically ill patients: does inferior vena cava collapsibility correlate with central venous pressure?

Comparison of inferior vena cava collapsibility and central venous pressure in assessing volume status in shocked patients

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An accurate diagnosis of shock state can be challenging, particularly in low-income countries, such as African countries, because physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap.

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Low-income countries therefore require easy and noninvasive methods, such as ultrasound devices.

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This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the management of shocked patients.

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We discovered that the inferior vena cava collapsibility index (IVC-ci) could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.

Introduction

Determination of intravascular volume status in patients admitted to the emergency centre is critical. Physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap, making an accurate diagnosis of shock state difficult. This is problematic because fluid loading is considered the first step in haemodynamically unstable patients’ resuscitation. Yet, multiple studies have shown that only approximately 50% of haemodynamically unstable patients in the intensive care unit and operating theatre respond to a fluid challenge. This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the assessment of volume status in shocked patients.

Methodology

This is a cross-sectional analytical study conducted on 102 shocked patients presented to the emergency centre. IV fluid boluses were standardized to be administered at 500 mL every 30 min over 120 min, as clinically indicated. Concurrent measurements of inferior vena cava collapsibility index (IVC-ci) were performed shortly before the initiation of IV bolus (i.e., time 0), and then at 30, 90, and 120 min, we measured both venous collapsibility index (CI) and central venous pressure (CVP). At each session, we recorded patient demographics, fluid responsiveness, and vital sign assessments.

Results

We discovered that IVC-ci at cut-off point 40 has a sensitivity of 93.3% and specificity of 70.7% with an AUC of 0.908 and a good 95% CI (0.84–0.975), implying that IVC-ci of 40% or higher can indicate fluid responsiveness in shocked patients. CVP, despite having a good sensitivity of 88.6%, high specificity of 100%, and a significant p-value, is not a reliable detector of fluid responsiveness due to its small AUC value and low 95% CI.

Conclusion

IVC-ci could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.

Point-of-Care Ultrasound for the Trauma Anesthesiologist

Purpose of Review

With advances in technology and availability of handheld ultrasound probes, studies are focusing on the perioperative care of patients, but a limited number specifically on trauma patients. This review highlights recent findings from studies using point of care ultrasound (POCUS) to improve the care of trauma patients.

Recent Findings

Major findings include the use of POCUS to assess volume status of trauma patients upon arrival to measure the major vasculature. Additionally, several studies have advanced the use of POCUS to identify pneumothorax in trauma patients. Finally, the ASA POCUS certification and ASRA expert guidelines are examples of international organizations establishing guidelines for utilization and training of anesthesiologists in the field of POCUS, which will be discussed.

Summary

Despite the COVID-19 pandemic, and considerable resources being diverted to fight this global healthcare crisis, advances are being made in utilization of POCUS to aid the care of trauma patients.

Ultrasonographic inferior vena cava diameter response to trauma resuscitation after 1 hour predicts 24-hour fluid requirement

BACKGROUND

Identification of occult hypovolemia in trauma patients is difficult. We hypothesized that in acute trauma patients, the response of ultrasound-measured minimum inferior vena cava diameter (IVCDMIN), IVC Collapsibility Index (IVCCI), minimum internal jugular diameter (IJVDMIN) or IJV Collapsibility Index (IJVCI) after up to 1 hour of fluid resuscitation would predict 24-hour resuscitation intravenous fluid requirements (24FR).

METHODS

An NTI-funded, American Association for the Surgery of Trauma Multi-Institutional Trials Committee prospective, cohort trial was conducted at four Level I Trauma Centers. Major trauma patients were screened for an IVCD of 12 mm or less or IVCCI of 50% or less on initial focused assessment sonographic evaluations for trauma. A second IVCD was obtained 40 minutes to 60 minutes later, after standard-of-care fluid resuscitation. Patients whose second measured IVCD was less than 10 mm were deemed nonrepleted (NONREPLETED), those 10 mm or greater were repleted (REPLETED). Prehospital and initial resuscitation fluids and 24FR were recorded. Demographics, Injury Severity Score, arterial blood gasses, length of stay, interventions, and complications were recorded. Means were compared by ANOVA and categorical variables were compared via χ. Receiver operating characteristic curves analysis was used to compare the measures as 24FR predictors.

RESULTS

There were 4,798 patients screened, 196 were identified with admission IVCD of 12 mm or IVCCI of 50% or less, 144 were enrolled. There were 86 REPLETED and 58 NONREPLETED. Demographics, initial hemodynamics, or laboratory measures were not significantly different. NONREPLETED had smaller IVCD (6.0 ± 3.7 mm vs. 14.2 ± 4.3 mm, p < 0.001) and higher IVCCI (41.7% ± 30.0% vs. 13.2% ± 12.7%, p < 0.001) but no significant difference in IJVD or IJVCCI. REPLETED had greater 24FR than NONREPLETED (2503 ± 1751 mL vs. 1,243 ± 1,130 mL, p = 0.003). Receiver operating characteristic analysis indicates IVCDMIN predicted 24FR (area under the curve [AUC], 0.74; 95% confidence interval [CI], 0.64-0.84; p < 0.001) as did IVCCI (AUC, 0.75; 95% CI, 0.65-0.85; p < 0.001) but not IJVDMIN (AUC, 0.48; 95% CI, 0.24-0.60; p = 0.747) or IJVCI (AUC, 0.54; 95% CI, 0.42-0.67; p = 0.591).

CONCLUSION

Ultrasound assessed IVCDMIN and IVCCI response initial resuscitation predicts 24-hour fluid resuscitation requirements.

LEVEL OF EVIDENCE

Diagnostic tests or criteria, level II.

The 2019-2020 Novel Coronavirus (Severe Acute Respiratory Syndrome Coronavirus 2) Pandemic: A Joint American College of Academic International Medicine-World Academic Council of Emergency Medicine Multidisciplinary COVID-19 Working Group Consensus Paper

What started as a cluster of patients with a mysterious respiratory illness in Wuhan, China, in December 2019, was later determined to be coronavirus disease 2019 (COVID-19). The pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel Betacoronavirus, was subsequently isolated as the causative agent. SARS-CoV-2 is transmitted by respiratory droplets and fomites and presents clinically with fever, fatigue, myalgias, conjunctivitis, anosmia, dysgeusia, sore throat, nasal congestion, cough, dyspnea, nausea, vomiting, and/or diarrhea. In most critical cases, symptoms can escalate into acute respiratory distress syndrome accompanied by a runaway inflammatory cytokine response and multiorgan failure. As of this article's publication date, COVID-19 has spread to approximately 200 countries and territories, with over 4.3 million infections and more than 290,000 deaths as it has escalated into a global pandemic. Public health concerns mount as the situation evolves with an increasing number of infection hotspots around the globe. New information about the virus is emerging just as rapidly. This has led to the prompt development of clinical patient risk stratification tools to aid in determining the need for testing, isolation, monitoring, ventilator support, and disposition. COVID-19 spread is rapid, including imported cases in travelers, cases among close contacts of known infected individuals, and community-acquired cases without a readily identifiable source of infection. Critical shortages of personal protective equipment and ventilators are compounding the stress on overburdened healthcare systems. The continued challenges of social distancing, containment, isolation, and surge capacity in already stressed hospitals, clinics, and emergency departments have led to a swell in technologically-assisted care delivery strategies, such as telemedicine and web-based triage. As the race to develop an effective vaccine intensifies, several clinical trials of antivirals and immune modulators are underway, though no reliable COVID-19-specific therapeutics (inclusive of some potentially effective single and multi-drug regimens) have been identified as of yet. With many nations and regions declaring a state of emergency, unprecedented quarantine, social distancing, and border closing efforts are underway. Implementation of social and physical isolation measures has caused sudden and profound economic hardship, with marked decreases in global trade and local small business activity alike, and full ramifications likely yet to be felt. Current state-of-science, mitigation strategies, possible therapies, ethical considerations for healthcare workers and policymakers, as well as lessons learned for this evolving global threat and the eventual return to a "new normal" are discussed in this article.

Fluid and hemodynamic management in hemodialysis patients: challenges and opportunities

Fluid volume and hemodynamic management in hemodialysis patients is an essential component of dialysis adequacy. Restoring salt and water homeostasis in hemodialysis patients has been a permanent quest by nephrologists summarized by the ‘dry weight’ probing approach. Although this clinical approach has been associated with benefits on cardiovascular outcome, it is now challenged by recent studies showing that intensity or aggressiveness to remove fluid during intermittent dialysis is associated with cardiovascular stress and potential organ damage. A more precise approach is required to improve cardiovascular outcome in this high-risk population. Fluid status assessment and monitoring rely on four components: clinical assessment, non-invasive instrumental tools (e.g., US, bioimpedance, blood volume monitoring), cardiac biomarkers (e.g. natriuretic peptides), and algorithm and sodium modeling to estimate mass transfer. Optimal management of fluid and sodium imbalance in dialysis patients consist in adjusting salt and fluid removal by dialysis (ultrafiltration, dialysate sodium) and by restricting salt intake and fluid gain between dialysis sessions. Modern technology using biosensors and feedback control tools embarked on dialysis machine, with sophisticated analytics will provide direct handling of sodium and water in a more precise and personalized way. It is envisaged in the near future that these tools will support physician decision making with high potential of improving cardiovascular outcome.

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.

Material 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.

The role of maximum compressed thickness of the quadriceps femoris muscle measured by ultrasonography in assessing nutritional risk in critically-ill patients with different volume statuses

SUMMARY PURPOSE In this prospective observational study, we aimed to investigate the role of the maximum compressed (MC) and uncompressed (UC) thickness of the quadriceps femoris muscle (QFMT) measured by ultrasonography (USG) in the detection of nutritional risk in intensive care patients (ICPs) with different volume status. METHODS 55 patients were included. Right, left, and total ucQFMT and mcQFMT measurements were obtained by a standard USG device within the first 48 hours after ICU admission. Clinical examination and the USG device were used to determine the volume status of the patients. SOFA, APACHE II, modified NUTRIC scores, and demographic data were collected. RESULTS There was a significant difference between the nutritional risk of patients in terms of left, right, and total mcQFMT measurements (p=0.025, p=0.039; p=0.028, respectively), mechanical ventilation requirement (p=0.014), presence of infection (p=0.019), and sepsis (p=0.006). There was no significant difference between different volume statuses in terms of mcQFMT measurements. In the multi-variance analysis, mcQFMT measurements were found to be independently associated with high nutritional risk (p=0.019, Exp(B)=0.256, 95%CI=0.082-0.800 for modified NUTRIC score ≥ 5), and higher nutritional risk (p=0.009, Exp(B)=0.144, 95%CI=0.033-0.620 for modified NUTRIC score ≥ 6). a Total mcQFMT value below 1.36 cm was a predictor for higher nutritional risk with 79% sensitivity and 70% specificity (AUC=0.749, p=0.002, likelihood ratio=2.04). CONCLUSION Ultrasonographic measurement of total mcQFMT can be used as a novel nutritional risk assessment parameter in medical ICPs with different volume statuses. Thus, patients who could benefit from aggressive nutritional therapy can be easily identified in these patient groups.

Pulmonary hypertension associated with left heart disease: Updated Recommendations of the Cologne Consensus Conference 2018

In the summer of 2016, delegates from the German Society of Cardiology (DGK), the German Respiratory Society (DGP), and the German Society of Pediatric Cardiology (DGPK) met in Cologne, Germany, to define consensus-based practice recommendations for the management of patients with pulmonary hypertension (PH). These recommendations were built on the 2015 European Pulmonary Hypertension guidelines, aiming at their practical implementation, considering country-specific issues, and including new evidence, where available. To this end, a number of working groups was initiated, one of which was specifically dedicated to PH associated with left heart disease. In this context, the European Guidelines point out that the drugs currently approved to treat patients with PAH (prostanoids, endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, sGC stimulators) have not sufficiently been investigated in other forms of PH. However, despite the lack of respective efficacy data, an uncritical use of targeted PAH drugs in patients with PH associated with left heart disease is currently observed at an increasing rate. This development is a matter of concern. On the other hand, PH is a frequent problem that is highly relevant for morbidity and mortality in patients with left heart disease. In that sense, the distinction between isolated post-capillary pulmonary hypertension (IpcPH) and combined post- and pre-capillary pulmonary hypertension (CpcPH) and their proper definition may be of particular relevance. The detailed results and recommendations of the working group on PH associated with left heart disease, which were last updated in the spring of 2018, are summarized in this article.

Echocardiographic Inferior Vena Cava Measurement As An Alternative to Central Venous Pressure Measurement in Neonates

OBJECTIVES

To evaluate the correlation between echocardiographic inferior vena cava (IVC) measurements and central venous pressure (CVP) in neonates. Also, to evaluate the correlation between IVC measurements and gestational age (GA) and body weight (BW).

METHODS

This cross sectional analytical study was conducted from June 2014 through June 2016 in a level III NICU. All neonates requiring intensive hemodynamic monitoring and having umbilical venous catheter (UVC) in place for clinical indications were enrolled in the study. IVC measurements were recorded by echocardiography (ECHO) and CVP was measured concomitantly in neonates having appropriate sized UVC in place. IVC measurements were evaluated and compared for any correlation with the CVP, GA and BW.

RESULTS

Fifty neonates with median gestation of 37 wk [Q1 = 29.2, Q3 = 37.8, interquartile range (IQR) = 8.6 wk] and median birth weight of 2420 g (Q1 = 923.5, Q3 = 2850, IQR = 1926.5 g) were included in the study. A strong negative linear correlation was observed between IVC collapsibility index (IVC-CI) and CVP (r = -0.968, r² = -0.937, p 0.000). No correlation was observed between IVC-CI and GA or BW. IVC minimum and IVC maximum diameters did not correlate with CVP but correlated well with GA and BW.

CONCLUSIONS

Echocardiographic IVC-CI measurement has a good correlation with CVP measurement in neonates. The clinical use will depend on the ability of IVC-CI to predict surrogate markers of tissue perfusion in shock.

Influence of the Respiratory Cycle on Caudal Vena Cava Diameter Measured by Sonography in Healthy Foals: A Pilot Study

Background

Intravascular volume assessment in foals is challenging. In humans, intravascular volume status is estimated by the caudal vena cava (CVC) collapsibility index (CVC‐CI) defined as (CVC diameter at maximum expiration [CVC_max] – CVC diameter at minimal inspiration [CVC_min])/CVC_max × 100%.

Hypothesis/Objectives

To determine whether the CVC could be sonographically measured in healthy foals, determine differences in CVC_max and CVC_min, and calculate inter‐ and intrarater variability between 2 examiners. We hypothesized that the CVC could be measured sonographically at the subxiphoid view and that there would be a difference between CVC_max and CVC_min values.

Animals

Sixty privately owned foals <1‐month‐old.

Methods

Prospective study. A longitudinal subxiphoid sonographic window in standing foals was used. The CVC_max and CVC_min were analyzed by a linear mixed effect model. Inter‐rater agreement and intrarater variability were expressed by Bland‐Altman and intraclass correlation coefficients, respectively.

Results

Measurements were attained from 58 of 60 foals with mean age of 15 ± 7.9 days and mean weight of 75.7 ± 17.7 kg. The CVC_max was significantly different from CVC_min (D = 0.515, SE = 0.031, P < 0.001). Inter‐rater agreement of the CVC‐CI differed by an average of −0.9% (95% limits of agreement, −12.5 to +10.7%). Intrarater variability of CVC_max was 0.540 and 0.545, of CVC_min was 0.550 and 0.594, and of CVC‐CI was 0.894 and 0.853 for observers 1 and 2, respectively.

Conclusions and Clinical Importance

These results indicate it is possible to reliably measure the CVC sonographically in healthy foals, and the CVC‐CI may prove useful in assessing the intravascular volume status in hypovolemic foals.

Keys to successful organ procurement: An experience-based review of clinical practices at a high-performing health-care organization

Organ procurement (OP) from donors after brain death and circulatory death represents the primary source of transplanted organs. Despite favorable laws and regulations, OP continues to face challenges for a number of reasons, including institutional, personal, and societal barriers. This focused review presents some of the key components of a successful OP program at a large, high-performing regional health network. This review focuses on effective team approaches, aggressive resuscitative strategies, optimal communication, family support, and community outreach efforts.

Noninvasive Assessment of Pulmonary Artery Pressure in Patients with Extracardiac Conduit Total Cavopulmonary Connection

To assess quantitative measurement of mean pulmonary artery pressure (PAP) in extracardiac total cavopulmonary connection (TCPC) patients by noninvasive echocardiographic inferior vena cava collapsibility index (IVC-CI) and also correlation between the peripheral vein pressure and mean PAP. In 19 TCPC patients with at least 1-year follow-up after completion of TCPC, complete echocardiography including IVC-CI was recorded. All patients underwent cardiac catheterization for mean PAP pressure, peripheral vein pressure (PVP) and contrast study. Different cutoff points of mean PAP were analyzed, and based on the highest cutoff point, patients were categorized into two groups: mean PAP < 17 mmHg (acceptable) and > = 17 mmHg (high) for comparison analysis. Between 2006 and 2015, from 43 patients who had undergone TCPC, nineteen patients with a mean age 12.9 ± 6.6 years and mean follow-up time of 3.4 ± 1.9 years were included in this study. Mean PAP was 14.6 ± 3.97 (range 8-22 mmHg). Thirteen (68 %) patients had PAP < 17 mmHg. No significant statistical difference was detected with respect to age, sex, type of congenital heart disease and fenestration between these two groups. But, right ventricular dominancy was more prevalent in the high PAP group (50 % vs. 7.7 % P value 0.03). IVC-CI had a correlation with mean PAP (r 0.67, P < 0.001). IVC-CI < 21.8 % can predict PAP > = 17 mmHg with 83 % sensitivity and 100 % specificity. Regression analysis proposed an equation for PAP measurement: PAP (mmHg) = 20.2097-0.1796 × (IVC-CI), (r2 = 0.56). Peripheral vein pressure measurement also showed a good correlation with mean PAP and may be used to estimate PAP with the following equation: PAP (mmHg) = 0. 8675 × PVP, (r 0.90, P < 0.0001). In conclusion, IVC-CI as noninvasive and peripheral vein pressure measurement as a minimal invasive method may be useful for quantitative estimation of PAP in patients with extracardiac TCPC.

Correlations between pulmonary artery pressures and inferior vena cava collapsibility in critically ill surgical patients: An exploratory study

INTRODUCTION

As pulmonary artery catheter (PAC) use declines, search continues for reliable and readily accessible minimally invasive hemodynamic monitoring alternatives. Although the correlation between inferior vena cava collapsibility index (IVC-CI) and central venous pressures (CVP) has been described previously, little information exists regarding the relationship between IVC-CI and pulmonary artery pressures (PAPs). The goal of this study is to bridge this important knowledge gap. We hypothesized that there would be an inverse correlation between IVC-CI and PAPs.

METHODS

A post hoc analysis of prospectively collected hemodynamic data was performed, examining correlations between IVC-CI and PAPs in a convenience sample of adult Surgical Intensive Care Unit patients. Concurrent measurements of IVC-CI and pulmonary arterial systolic (PAS), pulmonary arterial diastolic (PAD), and pulmonary arterial mean (PAM) pressures were performed. IVC-CI was calculated as ([IVCmax - IVCmin]/IVCmax) × 100%. Vena cava measurements were obtained by ultrasound-credentialed providers. For the purpose of correlative analysis, PAP measurements (PAS, PAD, and PAM) were grouped by terciles while the IVC-CI spectrum was divided into thirds (<33, 33-65, ≥66).

RESULTS

Data from 34 patients (12 women, 22 men, with median age of 59.5 years) were analyzed. Median Acute Physiologic Assessment and Chronic Health Evaluation II score was 9. A total of 76 measurement pairs were recorded, with 57% (43/76) obtained in mechanically ventilated patients. Correlations between IVC-CI and PAS (rs = -0.334), PAD (rs = -0.305), and PAM (rs = -0.329) were poor. Correlations were higher between CVP and PAS (R2 = 0.61), PAD (R2 = 0.68), and PAM (R2 = 0.70). High IVC-CI values (≥66%) consistently correlated with measurements in the lowest PAP ranges. Across all PAP groups (PAS, PAD, and PAM), there were no differences between the mean measurement values for the lower and middle IVC-CI ranges (0%-65%). However, all three groups had significantly lower mean measurement values for the ≥66% IVC-CI group.

CONCLUSIONS

Low PAS, PAD, and PAM measurements show a reasonable correlation with high IVC-CI (≥66%). These findings are consistent with previous descriptions of the relationship between IVC-CI and CVP. Additional research in this area is warranted to better describe the hemodynamic relationship between IVC-CI and PAPs, with the goal of further reduction in the reliance on the use of PACs.

Predicting Fluid Responsiveness Using Bedside Ultrasound Measurements of the Inferior Vena Cava and Physician Gestalt in the Emergency Department of an Urban Public Hospital in Sub-Saharan Africa

Background

Bedside inferior vena cava (IVC) ultrasound has been proposed as a non-invasive measure of volume status. We compared ultrasound measurements of the caval index (CI) and physician gestalt to predict blood pressure response in patients requiring intravenous fluid resuscitation.

Methods

This was a prospective study of adult emergency department patients requiring fluid resuscitation. A structured data sheet was used to record serial vital signs and the treating clinician’s impression of patient volume status and cause of hypotension. Bedside ultrasound CI measurements were performed at baseline and after each 500mL of fluid. Receiver operating characteristic (ROC) curve analysis was performed to characterize the relationship between CI and Physician gestalt, and the change in mean arterial pressure (MAP).

Results

We enrolled 364 patients, 52% male, mean age 36 years. Indications for fluid resuscitation were haemorrhage (54%), dehydration (30%), and sepsis (17%). Receiver operating characteristic curve analysis found optimal CI cut-off values of 45%, 52% and 53% to predict a MAP rise of 5, 8 and 10 mmHg per litre of fluid, respectively. The sensitivity and specificity of CI of 50% for predicting a 10mmHg increase in MAP per litre were 88% (95%CI 81–93%) and 73% (95%CI 67–79%), respectively, area under the curve (AUC) = 0.85 (0.81–0.89). The sensitivity and specificity of physician gestalt estimate of volume depletion severity were 68% (95%CI 60–75%) and 86% (95%CI 80–90%), respectively, AUC = 0.83 (95% CI: 0.79–0.87). Those with a baseline CI ≥ 50% (51% of patients) had a 2.8-fold greater fluid responsiveness than those with a baseline CI<50% (p<0.0001).

Conclusion

Ultrasound measurement of the CI can predict blood pressure response among patients requiring intravenous fluid resuscitation and may be useful in early identification of patients who will benefit most from volume resuscitation, and those who will likely require other interventions.

Echocardiography and Focused Cardiac Ultrasound

OBJECTIVES

The following review will describe the use of focused cardiac ultrasound performed by noncardiologists and its role as an acute hemodynamic monitoring tool in pediatric cardiac critical care.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

The use of focused cardiac ultrasound has grown tremendously over recent years, and is increasingly being performed and interpreted by intensivists, anesthesiologists, and emergency medicine physicians. These imaging techniques are useful in establishing etiologies of cardiac dysfunction and should compliment the physical examination and standard hemodynamic monitoring.

Measurement of the vascular pedicle width predicts fluid repletion: a cross-sectional comparison with inferior vena cava ultrasound and lung comets

Background

Determination of a patient’s volume status remains challenging. Ultrasound assessments of the inferior vena cava and lung parenchyma have been shown to reflect fluid status when compared to the more traditional static and dynamic methods. Yet, resource-limited intensive care units (ICUs) may still not have access to bedside ultrasound. The vascular pedicle width (VPW) measured on chest radiographs remains underutilized for fluid assessment. In this study, we aimed to determine the correlation between ultrasound assessment and vascular pedicle width and to identify a discriminant value that predicted a fluid replete state.

Methods

Eighty-four data points of simultaneous VPW and inferior vena cava measurements were collected on mechanically ventilated patients. VPW measurements were compared with lung comet scores, fluid balance, and a composite variable of inferior vena cava diameter greater than or equal to 2 cm and variability less than 15 %.

Results

A VPW of 64 mm accurately predicted fluid repletion with a positive predictive value equal to 88.5 % and an area under the curve (AUC) of 0.843, 95 % CI 0.75–0.93, p < 0.001. VPW closely correlated with inferior vena cava diameter (Pearson’s r = 0.64, p = <0.001). Poor correlations were observed between VPW and lung comet score, Pearson’s r = 0.12, p = 0.26, fluid balance, Pearson’s r = 0.3, p = 0.058, and beta natriuretic peptide, Pearson’s r = 0.12, p = 0.26.

Conclusions

This study shows a high predictive ability of the VPW for fluid repletion, as compared to an accepted method of volume assessment. Given the relationship of fluid overload and mortality, these results may assist fluid resuscitation in resource-limited intensive care units.

Dynamic behavior of venous collapsibility and central venous pressure during standardized crystalloid bolus: A prospective, observational, pilot study

INTRODUCTION

Measurement of intravascular volume status is an ongoing challenge for physicians in the surgical intensive care unit (SICU). Most surrogates for volume status, including central venous pressure (CVP) and pulmonary artery wedge pressure, require invasive lines associated with a number of potential complications. Sonographic assessment of the collapsibility of the inferior vena cava (IVC) has been described as a noninvasive method for determining volume status. The purpose of this study was to analyze the dynamic response in IVC collapsibility index (IVC-CI) to changes in CVP in SICU patients receiving fluid boluses for volume resuscitation.

MATERIALS AND METHODS

A prospective pilot study was conducted on a sample of SICU patients who met clinical indications for intravenous (IV) fluid bolus and who had preexisting central venous access. Boluses were standardized to crystalloid administration of either 500 mL over 30 min or 1,000 mL over 60 min, as clinically indicated. Concurrent measurements of venous CI (VCI) and CVP were conducted right before initiation of IV bolus (i.e. time 0) and then at 30 and 60 min (as applicable) after bolus initiation. Patient demographics, ventilatory parameters, and vital sign assessments were recorded, with descriptive outcomes reported due to the limited sample size.

RESULTS

Twenty patients received a total of 24 IV fluid boluses. There were five recorded 500 mL boluses given over 30 min and 19 recorded 1,000 mL boluses given over 60 min. Mean (median) CVP measured at 0, 30, and 60 minutes post-bolus were 6.04 ± 3.32 (6.5), 9.00 ± 3.41 (8.0), and 11.1 ± 3.91 (12.0) mmHg, respectively. Mean (median) IVC-CI values at 0, 30, and 60 min were 44.4 ± 25.2 (36.5), 26.5 ± 22.8 (15.6), and 25.2 ± 21.2 (14.8), respectively.

CONCLUSIONS

Observable changes in both VCI and CVP are apparent during an infusion of a standardized fluid bolus. Dynamic changes in VCI as a measurement of responsiveness to fluid bolus are inversely related to changes seen in CVP. Moreover, an IV bolus tends to produce an early response in VCI, while the CVP response is more gradual. Given the noninvasive nature of the measurement technique, VCI shows promise as a method of dynamically measuring patient response to fluid resuscitation. Further studies with larger sample sizes are warranted.

Prospective analysis of cardiac collapsibility of inferior vena cava using ultrasonography

PURPOSE

The inferior vena cava (IVC) diameter and its respiratory change (respiratory variation) reportedly correlate well with the central venous pressure and response to fluid. However, changes in the IVC diameter are related to the cardiac rhythm (cardiac variation), which can be useful as an indicator for intravascular volume but can affect respiratory variation. We conducted a prospective analysis of this cardiac variation in adult emergency department patients.

METHODS

Ultrasonographic IVC images from 190 consecutive adult emergency department patients were collected prospectively. The IVC diameters 2 cm caudal from the middle hepatic vein were tracked automatically and measured. The IVC diameter changes were analyzed using a software program that tracks 2-dimensional motion in B-mode images. Cardiac and respiratory variations were calculated and analyzed.

RESULTS

The average IVC cardiac variation was 11.0% (95% confidence interval, 9.8%-12.3%) in these patients, which affects the respiratory variation resulting in 1.68-fold higher overestimation of respiratory variation. The coefficient of correlation between IVC cardiac variations and respiratory variations was 0.34 (P < .05).

CONCLUSIONS

The IVC cardiac variation affects our interpretation of ultrasonography IVC imaging. The IVC cardiac variation provides several advantages over other parameters of intravascular volume. Therefore, it can be a novel tool to assess the intravascular volume of the patients.

Portable ultrasound in disaster triage: a focused review

Ultrasound technology has become ubiquitous in modern medicine. Its applications span the assessment of life-threatening trauma or hemodynamic conditions, to elective procedures such as image-guided peripheral nerve blocks. Sonographers have utilized ultrasound techniques in the pre-hospital setting, emergency departments, operating rooms, intensive care units, outpatient clinics, as well as during mass casualty and disaster management. Currently available ultrasound devices are more affordable, portable, and feature user-friendly interfaces, making them well suited for use in the demanding situation of a mass casualty incident (MCI) or disaster triage. We have reviewed the existing literature regarding the application of sonology in MCI and disaster scenarios, focusing on the most promising and practical ultrasound-based paradigms applicable in these settings.

Clinician-performed ultrasound in hemodynamic and cardiac assessment: a synopsis of current indications and limitations

Accurate hemodynamic and intravascular volume status assessment is essential in the diagnostic and therapeutic management of critically ill patients. Over the last two decades, a number of technological advances were translated into a variety of minimally invasive or non-invasive hemodynamic monitoring modalities. Despite the promise of less invasive technologies, the quality, reliability, reproducibility, and generalizability of resultant hemodynamic and intravascular volume status data have been lacking. Since its formal introduction, ultrasound technology has provided the medical community with a more standardized, higher quality, broadly applicable, and reproducible method of accomplishing the above-mentioned objectives. With the advent of portable, hand-carried devices, the importance of sonography in hemodynamic and volume status assessment became clear. From basic venous collapsibility and global cardiac assessment to more complex tasks such as the assessment of cardiac flow and tissue Doppler signals, the number of real-life indications for sonology continues to increase. This review will provide an outline of the essential ultrasound applications in hemodynamic and volume status assessment, focusing on evidence-based uses and indications.

Severe sepsis and septic shock: clinical overview and update on management

Sepsis is among the oldest themes in medicine; however, despite modern advances, it remains a leading cause of death in the United States. Every clinician should be able to recognize the signs and symptoms of sepsis, along with early management strategies, to expeditiously provide appropriate care and decrease resultant morbidity and mortality. This review addresses the definitions, pathogenesis, clinical manifestations, management, and outcomes of patients with sepsis, severe sepsis, and septic shock.

Non-invasive bedside assessment of central venous pressure: scanning into the future

BACKGROUND

Noninvasive evaluation of central venous pressure (CVP) can be achieved by assessing the Jugular Venous Pressure (JVP), Peripheral Venous Collapse (PVC), and ultrasound visualization of the inferior vena cava. The relative accuracy of these techniques compared to one another and their application by trainees of varying experience remains uncertain. We compare the application and utility of the JVP, PVC, and handheld Mini Echo amongst trainees of varying experience including a medical student, internal medicine resident, and cardiology fellow. We also introduce and validate a new physical exam technique to assess central venous pressures, the Anthem sign.

METHODS

Patients presenting for their regularly scheduled echocardiograms at the hospital echo department had clinical evaluations of their CVP using these non-invasive bedside techniques. The examiners were blinded to the echo results, each other's assessments, and patient history; their CVP estimates were compared to the gold standard level 3 echo-cardiographer's estimates at the completion of the study.

RESULTS

325 patients combined were examined (mean age 65, s.d. 16 years). When compared to the gold standard of central venous pressure by a level 3 echocardiographer, the JVP was the most sensitive at 86%, improving with clinical experience (p<0.01). The classic PVC technique and Anthem sign had better specificity compared to the JVP. Mini Echo estimates were comparable to physical exam assessments.

CONCLUSIONS

JVP evaluation is the most sensitive physical examination technique in CVP assessments. The PVC techniques along with the newly described Anthem sign may be of value for the early learner who still has not mastered the art of JVP assessment and in obese patients in whom JVP evaluation is problematic. Mini Echo estimates of CVPs are comparable to physical examination by trained clinicians and require less instruction. The use of Mini Echo in medical training should be further evaluated and encouraged.