Operability of a Resonance-Based Viscoelastic Haemostatic Analyzer in the High-Vibration Environment of Air Medical Transport

Abstract

Trauma and bleeding are associated with a high mortality, and most of these deaths occur early after injury. Viscoelastic haemostatic tests have gained increasing importance in goal-directed transfusion and bleeding management. A new generation of small-sized and thus portable ultrasound-based viscoelastic analysers have been introduced in clinical practice. We questioned whether a promising candidate can be used in emergency helicopters, with a focus on the susceptibility to vibration stress. We investigated whether the high vibration environment of an emergency helicopter would affect the operability of an ultrasound-based viscoelastic analyser and would yield reproducible results in flight and on the ground. We drew blood from 27 healthy volunteers and performed simultaneous analyses on two TEG 6s. Each measurement was performed in-flight on board an Airbus H135 emergency helicopter and was repeated on the ground, close to the flight area. Results from both measurements were compared, and the recorded tracings and numeric results were analysed for artifacts. Vibratometric measurements were performed throughout the flight in order to quantify changes in the magnitude and character of vibrations in different phases of helicopter operation. The high vibration environment was associated with the presence of artifacts in all recorded tracings. There were significant differences in citrated Kaolin + Heparinase measurements in-flight and on the ground. All other assays increased in variability but did not show significant differences between the two time points. We observed numerous artifacts in viscoelastic measurements that were performed in flight. Some parameters that were obtained from the same sample showed significant differences between in-flight and on-ground measurements. Performing resonance-based viscoelastic tests in helicopter medical service is prone to artifacts. However, a 10 min delay between initiation of measurement and take-off might produce more reliable results.

In vitro evaluation of a new viscoelastometry‐based point‐of‐care analyzer

“…However, the stress conditions in this study were modeled, which limits our interpretation of its hardiness. Zipperle et al demonstrated that simulating rotary wing settings does not substitute real‐life experimentation, as VHA exhibited inconsistent correlation with on‐ground testings 30 . Subsequently, a limited on‐field experiment followed our laboratory tests, bringing to light additional issues.…”

“…Zipperle et al demonstrated that simulating rotary wing settings does not substitute real-life experimentation, as VHA exhibited inconsistent correlation with on-ground testings. 30 Subsequently, a limited on-field experiment followed our laboratory tests, bringing to light additional issues. A field test was conducted by a medical team.…”

Point-of-care, goal-directed management of bleeding in trauma patients

“…The cartridge-based system used in TEG 6S and Quantra (HemoSonics, LLC, Durham, NC, USA) applies different methodologies. TEG 6s exposes coagulating blood to vibration frequencies and measures the resonance frequency caused by the motion of the blood meniscus [51,52]. Quantra is based on sonic estimation of elasticity via resonance (SEER), applying ultrasound to monitor changes in the viscoelastic properties of the clot [53][54][55].…”

Investigation and validation of the TEG6s during rotary wing aeromedical flight

“…[6][7][8][9] However, in practice, two prior studies trialed the device in a helicopter with disappointing results; those studies have significant limitations because of a lack of vibration mitigation. 10,11 Additional in-flight data are needed to assess the accuracy of those studies. This study aimed to investigate and validate the use of the TEG6s device (Haemonetics(R), Clinton PA) during helicopter flight.…”

“…Early published laboratory and simulation-based data suggested that the device would be stable and accurate in an aeromedical environment using rotary-wing aircraft 6–9 . However, in practice, two prior studies trialed the device in a helicopter with disappointing results; those studies have significant limitations because of a lack of vibration mitigation 10,11 . Additional in-flight data are needed to assess the accuracy of those studies.…”