Estimation of thoracic fluid content by using noninvasive cardiometry in critically ill children with acute kidney injury

ABSTRACT

Background:
Acute kidney injury (AKI) is frequently seen in critically ill children. Appropriate assessment of fluid status is needed in those with AKI as either excess fluid removal or fluid overload is associated with high morbidity and poor clinical outcome. This study aims to evaluate the clinical utility of thoracic fluid content (TFC) measured by cardiometry as an indicator of fluid status in critically ill children with AKI. Electrical cardiometry, a variation of impedance cardiography, is a device that measures stroke volume using changes in thoracic resistance associated with blood flow during the cardiac cycle, TFC is correlated with electrical impedance.


Subjects and Methods:

A cross-sectional study was done over 1 year including 72 critically ill children with AKI. Estimation of TFC has been made at the onset of AKI and during follow-up to determine the fluid status, in association with other clinical and imaging parameters.Patients were divided into two groups according to the management: the conservative group (
n
= 49) of patients who did not require renal replacement therapy and the dialysis group (
n
= 23).



Results:

TFC changes positively correlated with percent cumulative fluid balance (
r
= 0.316,
P
= 0.007) and with central venous pressure changes (
r
= 0.617,
P
= 0.002;
r
= 0.6,
P
= 0.00) in dialysis and conservative groups, respectively. Patients with fluid overload who have undergone dialysis had significantly higher median TFC compared to those not requiring dialysis or dialyzed for other indications both at the onset and follow-up of AKI (
P
= 0.03 and 0.043, respectively).



Conclusions:
TFC measurement by electrical impedance is a promising tool for monitoring fluid status in children with AKI.