Temperature Monitoring in Cardiac Surgery: Clinical Study of Agreement Between Different Measurement Methods
Conditions: Temperature Change, Body
Sponsor: Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León

 
Tittle: Temperature Monitoring in Cardiac Surgery: Agreement Between Different 
Clinical Methods 
NCT number: 04355013 
Document date:  27/04/2016 
 
 
Protocol  
Anesthetic management was similar in all patients. Operation room temperature was 
maintained at 19– 20°C. During the period prior to CPB, no active warming measures 
were used. After CBP, active warming of the patient was initiated using a convective 
blanket and heating the infusion fluids and those used in the surgical field to 39°C. During 
rewarming, the temperature of the arterial outlet line was limited to 37°C (maximum 
temperature of the heater cooler unit set at <38°C). 
 
Temperature monitoring  
After anesthesia induction, the following sites were used for simultaneous measurement 
of temperature: nasopharynx, via a probe inserted to a depth equal to the distance between 
the nares and the earlobe (Level 1® Oesophageal Stethoscope Temperature Sensor, 
Smiths Medical, Kent, UK), pulmonary artery (Continuous Cardiac Output Pulmonary 
Artery Catheter, Edwards Lifesciences, Irvine, CA), arterial outlet and venous inlet 
temperature probes (Stockert S5 Perfusion System, ¨ München, Germany), forehead using 
a TcoreTM double-sensor (Dragerwerk AG & Co, Lübeck, Germany), and ¨ urinary 
bladder (with the Level1® 400 series thermistor Foley catheter temperature sensor, 
Smiths Medical International Ltd, UK). Adequate positioning of sensors was confirmed 
at intervals throughout the study. 24 temperature measures per patient (1152 pairs of 
measurements) were recorded at 5-min intervals throughout surgery (8 readings in the 
pre-CPB period, 8 during the CPB period, and 8 after the weaning from CPB). The initial 
10 min measurements in each period were discarded since the forehead sensor needs 
about 10 min to reach equilibrium. We excluded pulmonary artery measurements during 
the CPB period. 
 
Statistics The Bland-Altman plot for repeated measures was used to assess concordance 
between methods. We a priori set the acceptable agreement (i.e., 95% limits of agreement) 
between methods to be 0.5°C. In addition, the percentage of measurement differences 
within the range of ±0.5°C and the 95% confidence interval for the proportion was 
estimated using bootstrap percentiles based on 10,000 resamples. Finally, for assessment 
of reproducibility, the Lin’s concordance correlation coefficient (LCCC) was computed 
and interpreted using McBride´s strength-of-agreement criteria for continuous variables 
(almost perfect: >0.99; substantial: >0.95– 0.99; moderate: 0.90–0.95; poor: < 0.05 were 
considered statistically significant. MedCalc® statistical software (MedCalc Software, 
Ostend, Belgium) was used for statistical analyses.