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J Reconstr Microsurg 2022; 38(02): 096-105
DOI: 10.1055/s-0041-1732426
Original Article

A Wireless Near-Infrared Spectroscopy Device for Flap Monitoring: Proof of Concept in a Porcine Musculocutaneous Flap Model

Changsheng Wu‡   *
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Alina Y. Rwei‡   *
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
2   Department of Chemical Engineering, Delft University of Technology, Delft, The Netherlands
,
Jong Yoon Lee 
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
3   Sibel Inc., Evanston, Illinois
,
Wei Ouyang
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Lauren Jacobson
4   Division of Plastic and Reconstructive Surgery, Department of Surgery, School of Medicine, Washington University, St. Louis, Missouri
,
Haixu Shen
5   Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois
,
Haiwen Luan
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Yameng Xu
6   Department of Neurosurgery, School of Medicine, Washington University, St. Louis, Missouri
,
Jun Bin Park
3   Sibel Inc., Evanston, Illinois
,
Sung Soo Kwak
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Xiaoyue Ni
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Wubin Bai
5   Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois
,
Daniel Franklin
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Shuo Li
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Yiming Liu
7   Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois
,
Xinchen Ni
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
,
Amanda M. Westman
4   Division of Plastic and Reconstructive Surgery, Department of Surgery, School of Medicine, Washington University, St. Louis, Missouri
,
Matthew R. MacEwan
6   Department of Neurosurgery, School of Medicine, Washington University, St. Louis, Missouri
,
John A. Rogers
1   Department of Materials Science and Engineering, Querrey Simpson Institute for Bioelectronics, Northwestern University, Chicago, Illinois
5   Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois
7   Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois
8   Department of Mechanical Engineering, Northwestern University, Evanston, Illinois
9   Department of Biomedical Engineering, Northwestern University, Evanston, Illinois
10   Department of Chemistry, Northwestern University, Evanston, Illinois
11   Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
,
Mitchell A. Pet 
4   Division of Plastic and Reconstructive Surgery, Department of Surgery, School of Medicine, Washington University, St. Louis, Missouri
› Author Affiliations Funding Funding for this study was received from the Division of Plastic Surgery and the Department of Neurosurgery at Washington University, and from the Querry Simpson Institute of Bioelectronics at Northwestern University.
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Abstract

Background Current near-infrared spectroscopy (NIRS)-based systems for continuous flap monitoring are highly sensitive for detecting malperfusion. However, the clinical utility and user experience are limited by the wired connection between the sensor and bedside console. This wire leads to instability of the flap–sensor interface and may cause false alarms.

Methods We present a novel wearable wireless NIRS sensor for continuous fasciocutaneous free flap monitoring. This waterproof silicone-encapsulated Bluetooth-enabled device contains two light-emitting diodes and two photodetectors in addition to a battery sufficient for 5 days of uninterrupted function. This novel device was compared with a ViOptix T.Ox monitor in a porcine rectus abdominus myocutaneous flap model of arterial and venous occlusions.

Results Devices were tested in four flaps using three animals. Both devices produced very similar tissue oxygen saturation (StO2) tracings throughout the vascular clamping events, with obvious and parallel changes occurring on arterial clamping, arterial release, venous clamping, and venous release. Small interdevice variations in absolute StO2 value readings and magnitude of change were observed. The normalized cross-correlation at zero lag describing correspondence between the novel NIRS and T.Ox devices was >0.99 in each trial.

Conclusion The wireless NIRS flap monitor is capable of detecting StO2 changes resultant from arterial vascular occlusive events. In this porcine flap model, the functionality of this novel sensor closely mirrored that of the T.Ox wired platform. This device is waterproof, highly adhesive, skin conforming, and has sufficient battery life to function for 5 days. Clinical testing is necessary to determine if this wireless functionality translates into fewer false-positive alarms and a better user experience.

Keywords

tissue perfusion monitoring - near-infrared spectroscopy - flap monitoring

* These authors contributed equally to this study.




Publication History

Received: 29 March 2021

Accepted: 12 May 2021

Article published online:
17 August 2021

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