Continuous Manual Agitation Significantly Improves Temperature Distribution During Closed HIPEC: Results Of A Porcine Model
*Tyler J Mouw, *Zachary Senders, *Prejesh Philips, *Charles R Scoggins, *Michael E Egger, Kelly M McMasters, Robert CG Martin
University of Louisville, Louisville, KY
OBJECTIVE(S): Debate still persists regarding the need for manual agitation, or shaking, during the closed technique for hyperthermic intraperitoneal chemotherapy (HIPEC). Studies assessing the thermal behaviors of the perfusate throughout the abdomen during HIPEC are lacking.
METHODS: A closed HIPEC technique was performed in a porcine model with a target outflow temperature of 40°C. The experimental protocol was approved by the institutional IACUC. Continuous temperature monitoring was conducted using thermal probes that were distributed throughout the abdomen and within the flow circuit. Shaking was performed for 60 second intervals and temperatures were allowed to equilibrate without shaking between intervals. Means were compared with t-tests. After shaking stopped, cold spots were considered to have formed when the difference between outflow and lowest temperature probe was statistically different from the time immediately after shaking stopped and was evaluated by repeated measures ANOVA.
RESULTS: The experimental procedure was conducted in two different animals and there were 6 total shaking intervals assessed. Prior to shaking, the outflow temperature overestimated the lowest internal temperatures by an average of 3.1°C (95% CI 2.4-3.8°C) (Figure 1). The locations of the most divergent temperatures varied based on catheter position. After 60 seconds of shaking, the minimum temperatures deviated from outflow temperature by an average of 0.7°C (0.3-1.0°C), for a total improvement of 2.4°C (1.4-3.4°C, p=0.003). The shaking time required to produce maximal homogeneity of temperatures was 26.8 (22.1-31.4) seconds. After shaking was stopped, the average time to the development of cold areas was 34.0 (13.0-54.9) seconds with a mean divergence of 1.2°C (0.8-1.7°C).
CONCLUSIONS: The use of outflow temperature alone is a poor metric for assessing internal temperatures during closed HIPEC. The utility is improved with shaking the abdomen. Cold areas relative to outflow temperature are rapidly corrected with shaking and rapidly re-develop after shaking stops, supporting the use of continuous manual agitation.
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