Contactless monitoring of heart and respiratory rate in anesthetized pigs using infrared thermography

PLoS One. 2019 Nov 6;14(11):e0224747. doi: 10.1371/journal.pone.0224747. eCollection 2019.

Abstract

Pig experiments have played an important role in medical breakthroughs during the last century. In fact, pigs are one of the major animal species used in translational research, surgical models and procedural training due to their anatomical and physiological similarities to humans. To ensure high bioethical standards in animal trials, new directives have been implemented, among others, to refine the procedures and minimize animals' stress and pain. This paper presents a contactless motion-based approach for monitoring cardiorespiratory signals (heart rate and respiratory rate) in anesthetized pigs using infrared thermography. Heart rate monitoring is estimated by measuring the vibrations (precordial motion) of the chest caused by the heartbeat. Respiratory rate, in turn, is computed by measuring the mechanical chest movements that accompany the respiratory cycle. To test the feasibility of this approach, thermal videos of 17 anesthetized pigs were acquired and analyzed. A high agreement between infrared thermography and a gold standard (electrocardiography and capnography-derived respiratory rate) was achieved. The mean absolute error averaged 3.43 ± 3.05 bpm and 0.27 ± 0.48 breaths/min for heart rate and respiratory rate, respectively. In sum, infrared thermography is capable of assessing cardiorespiratory signals in pigs. Future work should be conducted to evaluate infared thermography capability of capturing information for long term monitoring of research animals in a diverse set of facilities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Experimentation / ethics
  • Animal Welfare / ethics
  • Animals
  • Feasibility Studies
  • Heart Rate / physiology*
  • Infrared Rays
  • Models, Animal
  • Monitoring, Physiologic / ethics
  • Monitoring, Physiologic / instrumentation
  • Monitoring, Physiologic / methods*
  • Respiratory Rate / physiology*
  • Signal Processing, Computer-Assisted
  • Swine / physiology
  • Thermography / ethics
  • Thermography / instrumentation
  • Thermography / methods*

Grants and funding

The initial animal trial was supported by the German Research Foundation (DFG); M.C. received the grant number CZ 215/2-1. The IRT analysis including image and signal processing in the framework of this paper was also funded by the German Research Foundation (DFG); M.C. and R.T. received the following grants CZ 215/3-1 and TO 542/5-1, respectively. Note that DFG is a self-governed organization financed by the German states and the federal government. URL: https://www.dfg.de/en/index.jsp The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.