This study aimed to assess the precision and the interchangeability of cardiac index measurement by transpulmonary thermodilution (TPTD) and pulmonary thermodilution (PTD) devices on a neonatal animal model of acute respiratory distress syndrome under total liquid ventilation (TLV) and conventional mechanical ventilation (CMV). After acute respiratory distress induction by tracheal instillation of hydrochloric acid, transpulmonary (CITPTD) and pulmonary (CIPTD) cardiac index were simultaneously measured every 30 minutes for a 240-minute experiment. Reproducibility of both thermodilution techniques was very good to excellent in both groups of ventilation with intrainstrument intraclass correlation coefficient >0.60. Disagreement was found between TPTD and PTD in TLV and CMV. Bland-Altman analysis revealed mean biases of 0.98 L/min/m2 (22.8%) with limits of agreement of −1.33 to 3.25 L/min/m2 in CMV and 1.28 L/min/m2 (17.3%) with limits of agreement of −1.17 to 3.72 L/min/m2 in TLV. Bias between TPTD and PTD was not statistically different in TLV than in CMV (p = 0.11). Transpulmonary thermodilution and PTD remained precise but not interchangeable techniques under TLV as well as CMV. Because TLV does not bring additional bias between both thermodilution techniques, we advocate the use of the less-invasive TPTD under TLV as currently recommended in CMV.
From the *Département de Physiologie-Biophysique, Faculté de Médecine et des Sciences de la Santé; †Département de Pédiatrie, Faculté de Médecine et des Sciences de la Santé; ‡Département de Génie Mécanique, Faculté de Génie; and §Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Québec, Canada.
Submitted for consideration January 2010; accepted for publication in revised form July 2010.
H. Walti, O. Lesur, and J.-P. Praud are members of the Centre de recherche clinique Étienne-Lebel du Centre Hospitalier Universitaire de Sherbrooke. Pulsion medical system has provided the PiCCO and VoLEF devices for this study.
Reprint Requests: Dr. Hervé Walti, Département de Pédiatrie, Faculté de Médecine et des Sciences de la Santé, 3001, 12e Avenue Nord, Sherbrooke, Québec, Canada J1H 5N4. Email: email@example.com.