Measurement site of inferior vena cava diameter affects the accuracy with which fluid responsiveness can be predicted in spontaneously breathing patients: a post hoc analysis of two prospective cohorts

Morgan Caplan,Delphine Colling,Perrine Bortolotti,Thierry Onimus,Saad Nseir,Michael Howsam,Julien Goutay,Sebastien Preau,Raphael Favory,Anahita Rouze,Thibault Duburcq,Elodie Drumez,Arthur Durand

doi:10.1186/s13613-020-00786-1

Abstract

BackgroundThe collapsibility index of the inferior vena cava (cIVC) has potential for predicting fluid responsiveness in spontaneously breathing patients, but a standardized approach for measuring the inferior vena cava diameter has yet to be established.The aim was to test the accuracy of different measurement sites of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with sepsis-related circulatory failure and examine the influence of a standardized breathing manoeuvre.ResultsAmong the 81 patients included in the study, the median Simplified Acute Physiologic Score II was 34 (24; 42). Sepsis was of pulmonary origin in 49 patients (60%). Median volume expansion during the 24 h prior to study inclusion was 1000 mL (0; 2000). Patients were not severely ill: none were intubated, only 20% were on vasopressors, and all were apparently able to perform a standardized breathing exercise. Forty-one (51%) patients were responders to volume expansion (i.e. a ≥ 10% stroke volume index increase). The cIVC was calculated during non-standardized (cIVC-ns) and standardized breathing (cIVC-st) conditions. The accuracy with which both cIVC-ns and cIVC-st predicted fluid responsiveness differed significantly by measurement site (interaction p < 0.001 and < 0.0001, respectively). Measuring inferior vena cava diameters 4 cm caudal to the right atrium predicted fluid responsiveness with the best accuracy. At this site, a standardized breathing manoeuvre also significantly improved predictive power: areas under ROC curves [mean and (95% CI)] for cIVC-ns = 0.85 [0.78–0.94] versus cIVC-st = 0.98 [0.97–1.0], p < 0.001. When cIVC-ns is superior or equal to 33%, fluid responsiveness is predicted with a sensitivity of 66% and a specificity of 92%. When cIVC-st is superior or equal to 44%, fluid responsiveness is predicted with a sensitivity of 93% and a specificity of 98%.ConclusionThe accuracy with which cIVC measurements predict fluid responsiveness in spontaneously breathing patients depends on both the measurement site of inferior vena cava diameters and the breathing regime. Measuring inferior vena cava diameters during a standardized inhalation manoeuvre at 4 cm caudal to the right atrium seems to be the method by which to obtain cIVC measurements best-able to predict patients’ response to volume expansion.

Highlights

The collapsibility index of the inferior vena cava has potential for predicting fluid responsiveness in spontaneously breathing patients, but a standardized approach for measuring the inferior vena cava diameter has yet to be established.The aim was to test the accuracy of different measurement sites of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with sepsis-related circulatory failure and examine the influence of a standardized breathing manoeuvre
This study aimed to analyse the effect of the measurement site, and the use of a concomitant, standardized breathing manoeuvre, on the accuracy with which collapsibility index of the inferior vena cava (cIVC) measurements predict responsiveness to volume expansion (VE) in spontaneously breathing (SB) patients with sepsis
Our results confirm that clinicians should avoid measuring cIVC at site 0/1 [36], and suggests that the most reliable measurement site for predicting the cardiac response to VE is at 4 cm caudal from the cavo-atrial junction

Summary

Introduction

The collapsibility index of the inferior vena cava (cIVC) has potential for predicting fluid responsiveness in spontaneously breathing patients, but a standardized approach for measuring the inferior vena cava diameter has yet to be established.The aim was to test the accuracy of different measurement sites of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with sepsis-related circulatory failure and examine the influence of a standardized breathing manoeuvre. Developed for mechanically ventilated patients, use of these parameters has been proposed in spontaneously breathing (SB) patients in an effort to avoid unnecessary fluid exposure [14, 15]. Most of these dynamic parameters are unsuitable for SB patients. Under spontaneous breathing, respiratory changes in the stroke volume index (SVI) or their estimates (e.g. respiratory changes in arterial pulse pressure) are either inaccurate as predictors of FR [16], or too complex for routine clinical use [17, 18]. Passive leg raising-induced change in SVI is an accurate predictor, which has been validated in SB patients [19, 20]; but it requires a tool to measure (or estimate) cardiac output or stroke volume, and may be either technically impossible or unreliable under specific conditions (e.g. insufficient increase in central venous pressure during the procedure [21], pregnancy [22] or intra-abdominal hypertension [23, 24])

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