Description

Background

With over 300 million surgical procedures performed annually, surgery and anaesthesia provide major medical value to patients, especially in resource-rich countries like Switzerland with about 900.000 procedures done per year. Demand for surgery is expected to further increase in the coming years due to the aging of the population and the availability of novel less invasive surgical procedures making even elderly patients with extensive comorbidities possibly eligible for surgery.

Perioperative myocardial infarction/injury (PMI) has been identified as a major contributor to perioperative mortality. First studies estimated that PMI is a major contributor to 34-42% of all deaths following noncardiac surgery within 30 days. Recent research by several groups including ours has highlighted that PMI is not a homogenous disease entity, but seems to comprise several underlying pathophysiologies. These include type I myocardial infarction due to atherothrombosis, type II myocardial infarction due to myocardial oxygen supply-demand mismatch, tachyarrhythmias, acute heart failure, and PMI due to primarily extra-cardiac disorders such as severe sepsis, stroke, or pulmonary embolism. Unfortunately, the underlying pathophysiology of PMI remains unknown in many patients. This is among other things due to incomplete recording and documentation of patient vital signs including heart rate, blood pressure, and oxygen saturation e.g. in the postoperative period once patients leave the operating room. Identifying the underlying trigger of PMI is a prerequisite for causal therapy and prevention.

Objectives

1. To continuously document and quantify the frequency and duration of tachyarrhythmia, bradycardia, hypotension, hypertension, and/or hypoxemia, that are not recorded and documented using the current clinical monitoring standards, but detected using continuous monitoring of vital signs using the wearable device (Basler Band) throughout the whole perioperative period.
2. To validate the diagnosis of PMI within a screening program in high-risk patients undergoing major noncardiac surgery with other troponin assays.
3. To evaluate the diagnostic and predictive utility of novel biochemical markers.
4. To technically validate intraoperative haemodynamic measurements of wearable device by comparing them to routinely obtained intraoperative haemodynamics.

Number of Participants:

We expect PMI to occur in 15-20% of patients. We expect 35% of cases to fall in the adjudication category of "cardiac, unknown" in first adjudication. Continuous vital signs and biomarkers are expected to allow to adjudicate ~33% of PMI from the category "unknown" to any of the other definite categories. Using a Chi-square test for final analysis, we calculate a needed sample size of approximately 125 PMI. With worst-case PMI-incidence of 15%, and a buffer of 5% additional cases to compensate for technical difficulties which are expected to arise with continuous monitoring, we require a total sample size of 875 patients included into the cohort.

Methodology

After obtaining written informed consent, a venous specimen of blood (25 mL) is collected preoperatively and the patient will receive the wearable device. Further venous blood samples are withdrawn on postoperative days 1 and 2 (each 25 mL). As all patients will be included into the routine troponin screening implemented at the University Hospital Basel, blood draws will be coordinated with routine blood draws as far as possible. The wearable device will be worn until seven days after surgery or until hospital discharge.

Project duration for each patient will be approximately one week plus the answering of a questionnaire one year after the surgery.

Biobank

One preoperative and two postoperative venous blood samples are collected into plastic tubes containing sodium citrate 1:10 (4.3 mL), heparin (4.7 mL), ethylenediaminetetraacetic acid (EDTA, 7.5 mL) and a clotting activator for serum diagnostics (7.5 mL). The biological material collected will be coded and stored on study site (or in the biobank of the University Hospital Basel) for an indefinite period of time. During this timeframe the collected biological material can be used for future, not yet further defined research projects.

Wearable device: Basler Band (MMT 278-1 Bracelet) The multi-sensor wearable devices (Basler Band) will be provided by Manufacture Modules Technologies (MMT). The Basler Band relies on the MMT-CW287 multisensor technology to simultaneously and unobtrusively detect up to 9 core body parameters, and convey the information to physicians in a secure and GDPR- compliant fashion. It includes sensors and algorithms to measure heart rate, heart rate variability, heart rhythm, respiration rate and activity.