The temperature thresholds of <38.3°C (number of data pairs = 1560) and ≥38.3°C (number of data pairs = 1170) biases (limits of agreement) were −0.13°C (−0.42°C to +0.14°C) and −0.17°C (−0.46°C to +0.12°C), respectively. The sensitivity and specificity of the PACs to register the correct temperature at values ≥38.3°C were 99.9% (95% CI, 99.5%–100%) and 95.7% (95% CI, 92.8%–98.6%), respectively. The positive and negative predictive values for the PACs were 94.0% (95 CI%, 90.0%–98.0%) and 99.9% (95% CI, 99.6%–100%), respectively.
We found that the Edwards Lifesciences PAC provides generally reliable, sustained, and accurate measurement of patients’ body temperatures. Moreover, our study found that the Edwards PAC was accurate, regardless of the length of time during which the PAC was used and over a wide range of temperatures (36–40°C). Notably, with respect to the ability of the PACs to register temperatures over the fever threshold (≥38.3°C), the positive predictive value was 95.7%, which supports the use of the Edwards PAC for making clinical decisions. Only 4% of the data pairs were outliers, which was below the threshold of 15% defined before the study. These outliers involved 13 PACs, and most (80/114) were from 4 PACs (10.2% of the PACs tested). The latter accounted for 70% of the outliers, equally distributed (24, 19, 24, and 15 outliers, respectively) and were inserted for hemodynamic monitoring during cardiac surgery (2 mitral valve reconstruction, 1 aortic valve replacement, and 1 coronary artery bypass grafting). No problems during catheter insertion and no obvious dysfunction during the course of the catheters’ use (notably, pressure measurements and cardiac output allowed by the computer) were noted. Moreover, the external integrity of all catheters was checked before experimentation, and we observed no plication, stretching, and/or disruption of the catheters. Finally, the dysfunction of these 4 PACs was not associated with the duration of catheter use. These results could suggest that these particular PACs were defective, a possibility that has been previously reported.9
Although the PAC has been advocated as the “gold standard” for temperature monitoring in the ICU,1,10 it has clear drawbacks. The availability of alternative methods of measuring patient temperature is important because when fever (defined as a temperature ≥38.3°C) is observed clinically, general and specific investigations are conducted to determine the cause. Several studies have evaluated alternative methods for temperature measurement in ICU patients and compared the results with measurements obtained using PACs.2–6 Although temperature measurements obtained using PACs have been described in previous in vitro studies, meticulous laboratory conditions and precise statistical analysis were not used.11,12 Moreover, few studies have assessed the accuracy of the temperature measurements obtained using PACs with prolonged insertion where rheological strain, infusion of fluids and/or vasopressors, and other factors can distort the measurement. In studies comparing alternative temperature measurements with those obtained using the PAC, the duration of insertion was not specified.2–6
One strength of our study was the analysis of a large number of data pairs from PACs tested over a wide range of temperatures and inserted for durations ranging from 1 to 6 days. Nevertheless, some limitations were present. First, outliers were defined as values > ±0.3°C in PACs when compared with the PRT, which was based on our estimations that this error threshold was clinically relevant for clinical decision making. However, a meta-analysis of other temperature measurement strategies suggests that our choice was reasonable.13 Second, we did not study extreme temperature values (<36°C or >40°C), which may be observed clinically in conditions such as therapeutic hypothermia. Finally, we studied PACs only after removal from the patient and did not study any other temperature measurement strategy.
We found that temperature measurements provided by the Edwards Lifesciences PACs were clinically accurate across a wide range of temperatures and did not vary with duration of insertion. According to our testing, PACs are a clinically acceptable strategy for body temperature assessments in the ICU and may be used as a reference to establish and evaluate other methods of body temperature measurement.
The temperature measurements obtained using PACs were clinically accurate and were not affected by the length of use of the catheter or the range of temperatures assessed.
Name: Yoann Launey, MD.
Contribution: This author helped analyze the data and write the manuscript.
Attestation: Yoann Launey approved the final manuscript and attests to the integrity of the original data and the analysis reported in this manuscript.
Name: Raphaëlle Larmet, MD.
Contribution: This author helped conduct the study, analyze the data, and write the manuscript.
Attestation: Raphaëlle Larmet approved the final manuscript.
Name: Nicolas Nesseler, MD.
Contribution: This author helped write and review the manuscript.
Attestation: Nicolas Nesseler approved the final manuscript.
Name: Yannick Malledant, MD.
Contribution: This author helped design the study and write the manuscript.
Attestation: Yannick Malledant approved the final manuscript and attests to the integrity of the original data and the analyses reported in this manuscript.
Name: Clément Palpacuer, PharmD.
Contribution: This author helped analyze the data and write the manuscript.
Attestation: Palpacuer approved the final manuscript.
Name: Philippe Seguin, MD, PhD.
Contribution: This author helped design the study, analyze the data, and write the manuscript.
Attestation: Philippe Seguin approved the final manuscript, attests to the integrity of the original data and the analysis reported in this manuscript, and is also the archival author.
This manuscript was handled by: Avery Tung, MD.
We thank Dr. Frasca Denis for his help with the statistical analyses.
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