Open Access

ARTICLE

Effect of solute temperature in the measurement of cardiac output in children using the thermodilution technique

Shyam Sathanandam¹, Pooja Kashyap¹, David Zurakowski², Lindsey Bird¹, Vera McGhee³, Jeffrey Towbin¹, Benjamin Rush Waller III¹

1 Department of Pediatrics, Division of Pediatric Cardiology, LeBonheur Children’s Hospital, University of Tennessee, Memphis, Tennessee, USA
2 Department of Biostatistics, Harvard Medical School, Boston, Massachusetts, USA
3 UTHSC Health Science Center, College of Medicine, Memphis, Tennessee, USA

* Corresponding Author: Shyam Sathanandam, University of Tennessee Health Science Center, 848 Adams Avenue, Memphis, Tennessee 38103, USA. Email:

Congenital Heart Disease 2017, 12(2), 181-187. https://doi.org/10.1111/chd.12423

Abstract

Objectives: 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.
Design: This is a prospective, case control study.
Setting: Cardiac catheterization lab at Le Bonheur Children’s Hospital, Memphis, Tennessee.
Patients: 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%.
Interventions: 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.
Outcome Measures: 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 CTDCi. Mean difference (±SD) calculated by Bland-Altman analysis showed a higher score for RTDCi (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 ± 0.16℃ drop in BT compared to a 0.08 ± 0.19℃ 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.

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