Inferior vena cava diameter change after intravenous furosemide in patients diagnosed with acute decompensated heart failure

Point of Care Ultrasound for Diagnosis and Management in Heart Failure: A Targeted Literature Review

BACKGROUND

Cardiac point of care ultrasound (POCUS) has shown increasing utility as a tool for diagnosing and managing heart failure (HF). Within cardiology, intravascular volume assessment leveraging visualization of the inferior vena cava (IVC) is a central aspect of care, as IVC size correlates with central venous pressure. This targeted literature review aimed to examine the existing literature assessing the use of POCUS in diagnosis and management of HF patients utilizing POCUS-based IVC measurement either alone or in combination with secondary methods.

METHODS

A targeted PubMed and Ovid database search up until August 28, 2023 using a keyword search was completed. Studies that did not include IVC assessment with POCUS in HF were excluded.

RESULTS

The initial search using both PubMed and Ovid resulted in 370 journal publications. After exclusion criteria were used 15 studies were included in the review. Studies were grouped into three categories: 1) how well POCUS was able to identify HF, 2) whether POCUS-based findings correlated with other measures evaluating HF and was able to predict the effect of diuretic administration, and 3) whether POCUS-based findings served as a good prognostic indicator. The 5 studies that evaluated HF identification with POCUS found that both diagnostic sensitivity and specificity may reach 90%-100% when IVC measurement was coupled with a lung ultrasound assessing the presence of B-lines or pleural effusion. Five studies assessing POCUS findings correlating with other HF measures and diuretic effect found that IVC diameter changed significantly with diuretic administration (p<0.05). All 6 studies assessing POCUS as a predictor of long-term mortality or hospital readmission found measures that achieved statistical significance with p<0.05.

CONCLUSIONS

Including POCUS as standard-of-care - both as a diagnostic tool in the emergency department and a management tool in in-patient and out-patient facilities - may improve the treatment of HF.

The kinocardiograph for assessment of fluid status in patients with acute decompensated heart failure

AIMS

To improve telemonitoring strategies in heart failure patients, there is a need for novel non-obtrusive sensors that monitor parameters closely related to intracardiac filling pressures. This proof-of-concept study aims to evaluate the responsiveness of cardiac kinetic energy (KE) measured with the Kinocardiograph (KCG), consisting of a seismocardiographic (SCG) sensor and a ballistocardiographic (BCG) sensor, during treatment of patients with acute decompensated heart failure.

METHODS AND RESULTS

Eleven patients with acute decompensated heart failure who were hospitalized for treatment with intravenous diuretics received daily KCG measurements. The KCG measurements were compared with the diameter of the inferior vena cava (IVC) and body weight. Follow-up stopped at discharge, that is, in the recompensated state. Median (interquartile range) weight and IVC diameter decreased significantly after diuretic treatment [weight 74.5 (67.6-98.7) to 73.3 (66.7-95.6) kg, P = 0.003; IVC diameter 2.47 (2.33-2.99) to 1.78 (1.65-2.47) cm, P = 0.03]. In contrast with BCG measurements, significant changes in median KE measured with SCG were observed during the passive filling phase of the diastole [SGG: 0.48 (0.39-0.60) to 0.69 (0.56-0.84), P = 0.026; BCG: 0.68 (0.46-0.73) to 0.68 (0.59-0.82), P = 0.062], the active filling phase of the diastole [SCG: 0.38 (0.30-0.61) to 0.31 (0.09-0.47), P = 0.016; BCG: 0.29 (0.17-0.39) to 0.26 (0.20-0.34), P = 0.248], and the ratio between the passive and active filling phases [SCG: 2.76 (1.68-5.30) to 5.02 (3.13-10.17), P = 0.006; BCG: 5.87 (3.57-7.55) to 5.27 (3.95-9.43), P = 0.790]. The correlations between changes in KE during the passive and active filling phases, using SCG, and changes in weight or IVC were non-significant. Systolic KE did not show significant changes.

CONCLUSION

KE measured with the KCG using SCG is highly responsive to changes in fluid status. Future research is needed to confirm its accuracy in a larger study population and specifically its application for detection of clinical deterioration in the home-environment.

Inferior vena cava diameter and risk of acute decompensated heart failure rehospitalisations

OBJECTIVES

Inferior vena cava (IVC) diameter may be a surrogate for volume status in acute decompensated heart failure (ADHF). The utility of IVC diameter measurement is under studied. The aim of this study was to assess the relationship between IVC diameter, clinical variables and ADHF rehospitalisations.

METHODS

Retrospective chart review of 200 patients admitted for ADHF from 2018 to 2019 with transthoracic echocardiogram during index hospitalisation. Charts were assessed for ADHF rehospitalisation within 1 year.

RESULTS

The median age was 64, 30.5% were female, and average left ventricular ejection fraction was 41%±20%. IVC diameter correlated to pulmonary arterial (PA) pressure (R=0.347, p<0.001) and body surface area (BSA) (R=0.424 p<0.001). IVC diameter corrected for BSA correlated to PA pressure (R=0.287, p<0.001) and log N-terminal B-type natriuretic peptide (NT-proBNP) (R=0.247, p≤0.01). Patients rehospitalised within 1 year had significantly greater mean IVC diameter compared with those not rehospitalised (p<0.001) while there was no difference in mean net weight lost during index hospitalisation or mean log NT-proBNP. Patients with IVC diameter greater than 2.07 cm had significantly increased ADHF rehospitalisation (85.6% vs 49.3%, log rank p<0.001) with HR 2.44 (95% CI 1.85 to 3.23, p<0.001). In multivariable Cox regression only IVC diameter (p<0.001), presence of tricuspid regurgitation (p=0.02) and NYHA class III/IV (p<0.001) independently predicted ADHF rehospitalisation within 1 year.

CONCLUSIONS

IVC diameter is predictive of rehospitalisation in patients with ADHF and may identify patients in need of greater monitoring and diuresis.

Inferior vena cava diameter is associated with prognosis in patients with chronic heart failure independent of tricuspid regurgitation velocity

AIMS

A high, Doppler-derived, tricuspid regurgitation velocity (TRV) indicates pulmonary hypertension, which may contribute to right ventricular dysfunction and worsening tricuspid regurgitation leading to systemic venous congestion, reflected by an increase in inferior vena cava (IVC) diameter. We hypothesized that venous congestion rather than pulmonary hypertension would be more strongly associated with prognosis.

METHODS AND RESULTS

895 patients with chronic heart failure (CHF) (median (25th and 75th centile) age 75 (67-81) years, 69% men, LVEF 44 (34-55)% and NT-proBNP 1133 (423-2465) pg/ml) were enrolled. Compared to patients with normal IVC (< 21 mm) and TRV (≤ 2.8 m/s; n = 504, 56%), those with high TRV but normal IVC (n = 85, 9%) were older, more likely to be women and to have LVEF ≥ 50%, whilst those with dilated IVC but normal TRV (n = 142, 16%) had more signs of congestion and higher NT-proBNP. Patients (n = 164, 19%) with both dilated IVC and high TRV had the most signs of congestion and the highest NT-proBNP. During follow-up of 860 (435-1121) days, 239 patients died. Compared to those with both normal IVC and TRV (reference), patients with high TRV but normal IVC did not have a significantly increased mortality (HR: 1.41; CI: 0.87-2.29; P = 0.16). Risk was higher for patients with a dilated IVC but normal TRV (HR: 2.51; CI: 1.80-3.51; P < 0.001) or both a dilated IVC and elevated TRV (HR: 3.27; CI: 2.40-4.46; P < 0.001).

CONCLUSION

Amongst ambulatory patients with CHF, a dilated IVC is more closely associated with an adverse prognosis than an elevated TRV.

Assessment of filling pressures and fluid overload in heart failure: an updated perspective

Congestion plays a major role in the pathogenesis, presentation, and prognosis of heart failure and is an important therapeutic target. However, its severity and organ and compartment distribution vary widely among patients, illustrating the complexity of this phenomenon. Although clinical symptoms and signs are useful to assess congestion and manage volume status in individual patients, they have limited sensitivity and do not allow identification of congestion phenotype. This leads to diagnostic uncertainty and hampers therapeutic decision-making. The present article provides an updated overview of circulating biomarkers, imaging modalities (ie, cardiac and extracardiac ultrasound), and invasive techniques that might help clinicians to identify different congestion profiles and guide the management strategy in this diverse population of high-risk patients with heart failure.

High Inferior Vena Cava Diameter with High Left Ventricular End Systolic Diameter as a Risk Factor for Major Adverse Cardiovascular Events, Cardiovascular and Overall Mortality among Chronic Hemodialysis Patients

Background: Little is known about the association of inferior vena cava diameter (IVCD) and left ventricular end-systolic diameter (LVESD) with mortality in patients undergoing hemodialysis (HD). Methods: The single medical center observational cohort study enrolled 241 adult chronic HD patients from 1 October 2018 to 31 December 2018. Echocardiography results of IVCD and LVESD prior to dialysis were retrieved and patients were divided into high IVCD and low IVCD groups. Patients who received HD via a tunneled cuffed catheter were excluded. Study outcomes included all-cause mortality, cardiovascular mortality, and major adverse cardiovascular events (MACE). Subgroup analyses of HD patients with high and low LVESD were also performed. Results: The incidence of all-cause mortality, cardiovascular mortality, and MACE were higher in chronic HD patients with high IVCD (p < 0.01). High IVCD patients had significantly greater all-cause mortality, cardiovascular mortality, and MACE (log-rank test; p < 0.05). High IVCD patients are also associated with an increased risk of all-cause mortality and MACE relative to low IVCD patients (aHRs, 2.88 and 3.42; 95% CIs, 1.06−7.86 and 1.73−6.77, respectively; all p < 0.05). In the subgroup analysis of patients with high or low LVESD, the high IVCD remained a significant risk factor for all-cause mortality and MACE, and the HR is especially high in the high LVESD group. Conclusions: Dilated IVCD is a risk factor for all-cause mortality and MACE in chronic HD patients. In addition, these patients with high LVESD also have a significantly higher HR of all-cause mortality and MACE.

Monitoring patients with acute dyspnea with serial point-of-care ultrasound of the inferior vena cava (IVC) and the lungs (LUS): a systematic review

PURPOSE

The primary aim was to investigate if treatment guided by serial ultrasound of the inferior vena cava-collapsibility index (IVC-CI) and B-lines on lung ultrasound (LUS) could reduce mortality, readmissions, and length of stay (LOS) in acutely dyspneic patients admitted to a hospital, compared to standard monitoring. The secondary aim was to determine how the changes of B-lines and IVC-CI are correlated to vitals and symptoms.

METHODS

A systematic search was conducted on PubMed, Embase, Cochrane, Google Scholar, Web of Science, Scopus, OpenGrey, ProQuest, and databases for ongoing trials. The risk of bias was assessed according to study design.

RESULTS

Of the 8258 studies identified, 50 were selected for full-text screening, and 24 studies were chosen for data extraction (19 pre-post-, two non-randomized controlled-, two randomized controlled-, and one retrospective cohort study), covering 2040 patients. Most studies were single-center and had small study populations with only heart failure patients. The risk of bias was high. No studies evaluated how the difference between two ultrasound measurements correlated with the primary outcomes. Seven studies reported that a decline in either B-lines or IVC size, or an increased IVC-CI reduced mortality, readmissions, and LOS when correlated to a single ultrasound measurement. All studies showed changes in the IVC-CI and B-lines, but these were not related to vitals or symptoms.

CONCLUSION

B-lines and IVC-CI are dynamic variables that change over time and with treatment. A single ultrasound measurement can influence prognostic outcomes, but it remains uncertain if repeated scans can have the same impact.

Focused Cardiac Ultrasound to Detect Pre-capillary Pulmonary Hypertension

Background

Early recognition of pre-capillary (PC) pulmonary hypertension (PH) benefits dogs, allowing earlier treatment and improving prognosis. The value of focused cardiac ultrasound (FCU) to diagnose PH and assess its severity has not been investigated yet.

Hypothesis

A subjective 10-point FCU pulmonary hypertension score (PHS) allows diagnosis and assessment of severity of PCPH.

Animals

This study involved fifty client-owned dogs.

Methods

Dogs, recruited between September 2017 and February 2020, were classified into four categories (no, mild, moderate, and severe PH; C1 to C4, respectively). C1 and C2, and C3 and C4 were regrouped as group 1 and group 2, respectively. A blinded general practitioner assessed four FCU cineloops. Five echocardiographic parameters were subjectively scored, resulting in a total score of 0–10. Non-parametric tests compared global scores between categories and groups. A receiver operating characteristic (ROC) curve determined the cutoff value to differentiate group 1 and group 2. A gray zone approach allowed diagnosing or excluding moderate to severe PH with 90% certitude.

Results

Global scores were significantly higher for C4 than for C1, C2, and C3. Global scores of G2 were significantly higher than G1. The ROC curve indicated a cutoff value of 5, discriminating group 1 from group 2 with a sensitivity of 77% and a specificity of 100%. A score of ≥5/10 allowed diagnosing moderate to severe PH with ≥90% certainty while a score of ≤2/10 excluded PH with ≥90% certainty.

Conclusions and Clinical Significance

Moderate to severe PCPH can be accurately detected by non-cardiologists using a 10-point FCU PHS score.

The Use of POCUS to Manage ICU Patients With COVID-19

Since the advent of SARS-CoV-2, the virus that causes COVID-19, clinicians have had to modify how they provide high-value care while mitigating the risk of viral spread. Routine imaging studies have been discouraged due to elevated transmission risk. Patients who have been diagnosed with COVID-19 often have a protracted hospital course with progression of disease. Given the need for close follow-up of patients, we recommend the use of ultrasonography, particularly point-of-care ultrasound (POCUS), to manage patients with COVID-19 through their entire ICU course. POCUS will allow a clinician to evaluate and monitor cardiac and pulmonary function, as well as evaluate for thromboembolic disease, place an endotracheal tube, confirm central venous catheter placement, and rule out a pneumothorax. If a patient improves sufficiently to perform weaning trials, POCUS can also help evaluate readiness for ventilator liberation.

Monitoring patients with acute dyspnoea with a serial focused ultrasound of the heart and the lungs (MODUS): a protocol for a multicentre, randomised, open-label, pragmatic and controlled trial

INTRODUCTION

Among patients admitted to an emergency department, dyspnoea is one of the most common symptoms. Patients with dyspnoea have high mortality and morbidity. Therefore, novel methods to monitor the patients are warranted. The aim is to investigate whether therapy guided by monitoring patients with acute dyspnoea with serial ultrasound examinations of the heart and the lungs together with standard care can change the severity of dyspnoea compared with treatment guided by standard monitoring alone.

METHODS AND ANALYSIS

The study will be conducted as a multicentre, randomised, pragmatic, open-label and controlled trial where patients admitted with acute dyspnoea to an emergency ward will be randomised into a standard care group and a serial ultrasound group with 103 patients in each. All patients will be examined with an ultrasound of the heart and the lungs upfront. In addition, the patients in the serial ultrasound group will be examined with an ultrasound of the heart and lungs two more times to guide further therapy during the admittance. The primary outcome is a change in dyspnoea on a verbal scale. After discharge, the patients are followed for 1 year to assess the number of readmissions, death and length of hospital stay.

ETHICS AND DISSEMINATION

The trial is conducted in accordance with the Declaration of Helsinki and approved by The Regional Committee on Health Research Ethics for Region Zealand, Denmark (identifier SJ-744). Data handling agreement with participating centres has been made (identifier REG-056-2019). The General Data Protection Regulation and the Danish Data Protection Act will be respected. The results of the trial will be reported in peer-reviewed scientific journals regardless of the outcomes.

TRIAL REGISTRATION NUMBER

NCT04091334.

Effectiveness of serial focused ultrasound of the lungs and inferior vena cava for monitoring patients with acute dyspnea: a systematic review protocol

OBJECTIVE

The objective of this review is to evaluate the effectiveness of serial focused ultrasound of the lungs (FLUS) and/or inferior vena cava (IVC) compared to standard care for monitoring patients with acute dyspnea.

INTRODUCTION

Acute dyspnea is one of the most common complaints reported by patients in hospital emergency departments, and has high in-hospital mortality rates. The current methods of monitoring patients with acute dyspnea lack both sensitivity and specificity. Point-of-care FLUS and IVC is a promising monitoring tool, but an overview of the existing evidence is absent.

INCLUSION CRITERIA

This review will include studies of adult patients admitted to hospital with acute dyspnea that is examined via FLUS, IVC or both a minimum of twice during hospitalization compared to standard care.

METHODS

The following electronic databases will be searched: PubMed, Cochrane, Embase, Scopus, Web of Science and Google Scholar. Gray literature will be sought in OpenGrey and ProQuest. The search is limited to articles written in English, Danish, Swedish, Norwegian and German. Articles published before 2003 will be excluded from the search and duplicates will be removed. Two independent reviewers will screen and critically appraise the included studies and perform the data extraction. If possible, data will be synthesized with statistical meta-analysis; otherwise, data will be presented in narrative form.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42018116608.

Limited agreement between two noninvasive measurements of blood volume during fluid removal: ultrasound of inferior vena cava and finger-clip spectrophotometry of hemoglobin concentration

OBJECTIVE

Plots of blood volume measurements over time (profiles) may identify euvolemia during fluid removal for acute heart failure. We assessed agreement between two noninvasive measurements of blood volume profiles during mechanical fluid removal, which exemplifies the interstitial fluid shifts that occur during diuretic-induced fluid removal.

APPROACH

During hemodialysis we compared change in maximum diameter of the inferior vena cava by ultrasound ([Formula: see text]) to change in relative blood volume derived from capillary hemoglobin concentration from finger-clip spectrophotometry (RBV_SpHb). We grouped profiles of these measurements into three distinct shapes using an unbiased, data-driven modeling technique.

METHODS

Fifty patients who were not in acute heart failure underwent a mean of five paired measurements while an average of 1.3 liters of fluid was removed over 2 h during single hemodialysis sessions. [Formula: see text] changed  -1.0 mm (95% CI  -1.9 to  -0.2 mm) and the RBV_SpHb changed  -1.1% (95% CI  -2.7 to  +0.5%), but these changes were not correlated (r  -0.04, 95% CI  -0.32 to  +0.24). Nor was there agreement between categorization of profiles of change in the two measurements (kappa  -0.1, 95% CI  -0.3 to  +0.1).

SIGNIFICANCE

[Formula: see text] and RBV_SpHb estimates of blood volume do not agree during mechanical fluid removal, likely because regional changes in blood flow and pressure modify IVC dimensions as well as changes total blood volume.

Comparison between inferior vena cava ultrasound, lung ultrasound, bioelectric impedance analysis, and natriuretic peptides in chronic heart failure

BACKGROUND

Heart failure (HF) is an important healthcare problem. Knowing volume status in outpatients with chronic HF to adjust treatment and to avoid decompensations is a challenge. The aim of this study is comparing the usefulness of inferior vena cava (IVC) ultrasound, lung ultrasound, bioelectrical impedance analysis (BIA), and natriuretic peptides in the follow-up of outpatients with chronic HF.

METHODS

This was a prospective cohort study. Ninety-nine patients with chronic HF were included consecutively as they attended scheduled medical visits. The different techniques were performed on the day of the clinic visit, and the result was hidden from the patients and the responsible medical team. Follow-up time was 1 year. Outcome events checked were a combination of death or hospitalization, due to HF.

RESULTS

Thirty-six patients (36.4%) died or were hospitalized for HF. They had a significantly lower IVC collapse, and a greater number of lung B-lines and higher NTproBNP levels compared to patients who remained stable. There were no differences in the BIA parameters. After multivariable analysis, cut-off points of IVC collapse <30%, number of pulmonary B lines greater than 5, and NTproBNP levels greater than 2000 pg/ml were associated with increased risk of HF death or admission. NTproBNP had the best area under the curve.

CONCLUSION

Evaluation of congestion in outpatients with chronic HF may be based on NTproBNP, IVC ultrasound, or lung ultrasound; they are useful in identifying patients at high risk of hospitalization or death due to HF.

Usefulness of inferior vena cava ultrasonography in outpatients with chronic heart failure

BACKGROUND

Inferior vena cava (IVC) ultrasonography has been used for the diagnosis and prognosis of acute heart failure (HF). Its usefulness in chronic HF is less known.

HYPOTHESIS

IVC ultrasonography is a useful tool in the care of patients with chronic HF.

METHODS

For this prospective cohort study, 95 patients with chronic HF were included consecutively as they attended scheduled medical visits. Ultrasound was done with a 5-MHz convex probe device, calculating IVC collapse index (IVCCI). Follow-up time was 1 year. Outcome events were worsening HF, hospital admission for HF, HF mortality, and all-cause mortality.

RESULTS

Worsening HF occurred in 70.9% of patients with IVCCI <30% and 39.1% of patients with IVCCI >50%, with a hazard ratio (HR) of 2.8 (95% CI: 1.3-6.2) adjusted by multivariable analysis. Regarding hospitalization, 45.3% of patients with IVCCI <30% required admission, compared with 5.9% of patients with IVCCI >50%; the adjusted HR was 13.9 (95% CI: 1.7-113.0). Mortality was higher in the IVCCI <30% group, with 25.7% all-cause mortality and 18.6% HF mortality, whereas in the IVCCI >50% group these values were 13% and 4.7%, respectively. However, these differences did not reach statistical significance. ROC analysis was performed and the AUC for IVCCI was not higher than that for NTproBNP for any of the outcomes studied.

CONCLUSIONS

IVC ultrasonography is a useful tool in follow-up of patients with chronic HF, allowing identification of patients at high risk of worsening and hospitalization. However, its usefulness is not higher than that of NTproBNP.

Reconsideration of Inferior Vena Cava Parameters for Estimating Right Atrial Pressure in an East Asian Population - Comparative Simultaneous Ultrasound-Catheterization Study

BACKGROUND

Ultrasound measurements of the inferior vena cava (IVC) diameter (IVCD), together with its respiratory variation, provide a noninvasive estimate of right atrial pressure (RAP). However, there is a paucity of studies that have compared this technique with simultaneous catheterization. We explored the best cut-off values of IVC parameters for elevated RAP in comparison with RAP measured by catheterization.Methods and Results:We prospectively enrolled 120 East Asian patients who were scheduled for catheterization. The IVCD and IVC collapsibility index (IVCCI) were measured according to the current guidelines. The optimal maximum IVCD (IVCDmax) and IVCCI cut-offs for detecting elevated RAP (RAP ≥10 mmHg) were 17 mm and 40%, respectively. When we combined both in proportion to the guidelines, the sensitivity and specificity for detecting elevated RAP were 75% and 94%, respectively. When the cut-off values from the current guidelines (>21 mm and <50%) were applied, the respective sensitivity and specificity were 42% and 99%. Interestingly, the cut-off value of the optimal IVCDmax indexed by body surface area (11 mm/m²) was similar to previous Western population data. When we combined both cut-off values (11 mm/m²and 40%), the sensitivity and specificity were 75% and 95%, respectively.

CONCLUSIONS

The optimal absolute IVCDmax and IVCCI cut-offs to detect elevated RAP were smaller than those in the current guidelines. Indexed IVCDmax may be an IVC parameter that can be used internationally.

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.