Evaluation of Digital Thermal Monitoring as a Tool to Assess Perioperative Vascular Reactivity

Abstract

Aim:The inflammatory response following tissue injury after major surgery is known to affect endothelial function and vascular reactivity. In this study we evaluated the utility of bedside Digital Thermal Monitoring (DTM) as a surrogate for evaluating vascular function in the postoperative period. Methods: Ischemia-induced reactive hyperemia variables were measured in sixty patients scheduled for major thoracic surgery using DTM (VENDYS 5000BC; Endothelix, Inc., Houston, TX, USA) at baseline and at 24, 48, 72 hours, and day 5 postoperatively. Furthermore, baseline DTM variables (TR, aTR and AUCTR) and postoperative kinetics of these variables were compared among patients with and without preoperative chemo-radiation and cardiovascular risk factors. Results: There were no significant differences in the DTM parameters measured at baseline and on each of the studied postoperative days. Compared to the baseline, the lowest measures of all variables were observed 24 hrs postoperatively and the highest measures of all variables were observed at 72 hrs. Patients with abdominal obesity and smoking had lower DTM values than the rest of the study group. Conclusions: In our study, DTM as measured by the VENDYS 5000BC DTM system (Endothelix, Inc.) did not reveal significant changes in ischemia-induced reactive hyperemia (vascular reactivity) between the baseline and after surgery in the postoperative period. Patients with certain cardiovascular risk factors (abdominal obesity, smoking) had a significant lower DTM signal. Whether this novel non-invasive technique is able to serve as a perioperative diagnostic tool for patients in a clinical setting warrants further study. J Atheroscler Thromb, 2013; 20:277-286.

Perioperative Implications of Vascular Endothelial Dysfunction: Current Understanding of this Critical Sensor-Effector Organ

“…We observed a lower DTM signal in patients with cardiovascular risk factors (abdominal obesity, smoking) and this may contribute to further risk stratification of these patients. However, unlike the findings of Hu et al [18 •• ], we were unable to show significant DTM changes in the perioperative period following major thoracic surgery [23].…”

“…The link between inflammation, endothelial dysfunction and vascular events is supported by the observation in population studies of a seasonal variation in myocardial infarction; with increased incidence in the winter months when inflammatory infections occur more frequently [22]. It is this combination of post-surgical inflammation, endothelial dysfunction, and a prothrombotic state that increases the risk of microvascular impairment and postoperative morbidity, and is likely to be more evident in patients with marginal preoperative (baseline) endothelial function [4,23].…”

“…These tools are increasingly being explored as methods of improving preoperative risk stratification [4,5,23,28,29], improving our understanding of the pathophysiology of perioperative endothelial dysfunction [18 •• ], and our understanding of potential therapeutic strategies [30]. As such, endothelial vasodilator dysfunction has been shown to be predictive of short and long-term postoperative cardiovascular events in patients undergoing vascular surgery [4].…”

The role of vascular biomarkers for primary and secondary prevention. A position paper from the European Society of Cardiology Working Group on peripheral circulation

“…Endurance exercise leads to improved central haemodynamics [289] and endothelial function [290]; the effect of high-intensity resistance training on arterial stiffness is detrimental [290]. Beneficial effects have been reported following smoking cessation [162].…”

“…DTM (Endothelix Inc., Houston, TX, U.S.A.) is a technique that shares the same pathophysiological background with FMD using temperature as a surrogate marker of blood flow; nevertheless few studies with small sample sizes have been published to date [162,163], Similarly, DVP has been used for endothelial function assessment on top of its use for pulse wave analysis [164], but there are limited published data to date [165].…”