Effect of solute temperature in the measurement of cardiac output in children using the thermodilution technique.
OBJECTIVE
The primary aim of this study was to compare thermodilution (TD) cardiac index (TDCi) measured by injecting cold saline (C-TDCi) to saline at room temperature (R-TDCi). The secondary aim was to assess the change in body temperature with cold saline injections in children.


METHODS
This is a prospective, case control study.


METHODS
Cardiac catheterization lab at Le Bonheur Children's Hospital, Memphis, Tennessee.


METHODS
Eighty-six children ≤18 years of age that underwent cardiac catheterization between April 2013 and April 2015, excluding patients with admixing lesions, on inotropic support and with ejection fraction < 30%.


METHODS
A TD catheter in the main pulmonary artery was used to measure cardiac output (CO). Each patient received manual injections of saline at room temperature followed by cold saline to calculate the CO.


METHODS
CO by C-TDCi, R-TDCi, and Fick-Ci were compared using four different statistical methods.


RESULTS
R-TDCi and Fick-Ci had a strong linear correlation (rho = 0.91 and 0.77, respectively; P < 0.0001) to C-TDCi. R-TDCi and Fick-Ci also had high 1:1 intra-class correlation to C-TDCi (ICC-rho= 0.82 and 0.68, respectively; P < 0.01). 96% confidence limits by equivalence testing for R-TDCi and Fick-Ci were 0.98-1.02 and 0.96-1.05 respectively (P < 0.0001), when compared to C-TDCi. Mean difference (±SD) calculated by Bland-Altman analysis showed a higher score for R-TDCi (0.012 ± 0.32 L/min/m2) compared to Fick-Ci (0.2 ± 0.72 L/min/m2), but it was not statistically different (P = 0.25). In a subgroup analysis of children ≤2 years (n = 27), the results from all 3 techniques were equivalent. There was a 0.2 ± 0.16ºC drop in BT compared to a 0.08 ± 0.19ºC drop in those >2 years (P > 0.05).


CONCLUSIONS
Cardiac indexes determined by Fick, C-TDCi, and R-TDCi were equivalent in children. Saline at room temperature can be used as an alternative to cold saline to avoid potential drop in body temperature of these patients.
Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children's Hospital, University of Tennessee, Memphis, Tennessee, USA.
Shyam
S
Sathanandam
Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children's Hospital, University of Tennessee, Memphis, Tennessee, USA.
Pooja
P
Kashyap
Department of Biostatistics, Harvard Medical School, Boston, Massachusetts, USA.
David
D
Zurakowski
Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children's Hospital, University of Tennessee, Memphis, Tennessee, USA.
Lindsey
L
Bird
UTHSC Health Science Center, College of Medicine, Memphis, Tennessee, USA.
Vera
V
McGhee
Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children's Hospital, University of Tennessee, Memphis, Tennessee, USA.
Jeffrey
J
Towbin
Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children's Hospital, University of Tennessee, Memphis, Tennessee, USA.
Benjamin
B
Rush Waller
D000293:Adolescent; D000367:Age Factors; D001833:Body Temperature Regulation; D006328:Cardiac Catheterization; D002302:Cardiac Output; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003080:Cold Temperature; D005260:Female; D006801:Humans; D007223:Infant; D007267:Injections; D016014:Linear Models; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012965:Sodium Chloride / Q000008:administration & dosage*; D013714:Tennessee; D013815:Thermodilution / Q000379:methods*
D012965:Sodium Chloride
cardiac output; catheterization; pediatrics