Comparison of iced and room temperature injectate for thermodilution cardiac output

Abstract

Cardiac output estimation by thermodilution is carried out using room temperature or iced injectate, but the accuracy and variability of the two methods is not well documented. Room temperature and iced injectate were compared in 21 patients undergoing diagnostic cardiac catheterization. Dextrose injectate (10 ml) was administered in prefilled syringes left to stand either in iced water or in room air. Four injections were made sequentially with room temperature and iced injectate. Cardiac output by room temperature and iced injectate were not significantly different (4.70 +/- 1.22 for room temperature and 4.90 +/- 1.37 for iced injectate, n = 21, P = 0.155). There was a significant difference in the variance of the estimations by the two methods (room temperature = 0.296, iced = 0.120, P less than 0.005). From this variance the calculated number of measurements needed to estimate cardiac output to +/- 0.5 L/min with 95% confidence is seven for room temperature and four for iced injectate. For five patients with cardiac output less than 4.00 L/min with room temperature injectate, cardiac output with iced injectate was significantly higher (3.33 +/- 0.34 for room temperature vs. 3.69 +/- 0.49 for iced injectate, P = 0.05). Thus room temperature injectate generally gives a satisfactory cardiac output estimation but with significantly greater variability than iced injectate. Sample size for accurate cardiac output estimation must be greater with room temperature injectate. Iced injectate may over-estimate output when cardiac output is low.

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

“…Similar finding was noted also by Runciman et al in a previous large animal study. Bourdillon and Fienberg found that there was variation in the measurements obtained by R‐TDCi and C‐TDCi. An average of seven measurements of R‐TDCi when compared to an average of four measurements of C‐TDCi were used to decrease variability.…”

Iced vs Room-Temperature Injectates for Cardiac Index Measurement During Hypothermia and Normothermia

“…Although room-temperature and iced injectates have been compared in numerous studies, [1][2][3][4][6][7][8][9][10][11][12][13][14][15][16][17] many of the studies had deficiencies that make generalization of their findings difficult. Some of the studies used an open system (individual syringes filled with fluid) to deliver the injectates, a practice that was common at one time, [2][3][4][10][11][12][14][15][16] or did not describe the delivery system.…”

“…Some of the studies used an open system (individual syringes filled with fluid) to deliver the injectates, a practice that was common at one time, [2][3][4][10][11][12][14][15][16] or did not describe the delivery system. 1,3,8,17 Very few studies have examined the accuracy of measurements made with room-temperature injectate in closed injectate delivery systems.…”

“…A number of variables can influence the accuracy and reproducibility of cardiac index measurements, including volume of injectate, [1][2][3][4][5] injectate delivery system, 6,7 temperature of injectate, [1][2][3][4][6][7][8][9][10][11][12][13][14][15][16][17] positioning, [18][19][20][21][22] and injection technique. 16,23,24 Studies of the influence of each of the variables have been reviewed [25][26][27] and published as evidence-based practice guidelines for thermodilution measurement of cardiac output.…”