Real-Time Monitoring for Detection of Retained Surgical Sponges and Team Motion in the Surgical Operation Room Using Radio-Frequency-Identification (RFID) Technology: A Preclinical Evaluation

Background

Technical progress in the surgical operating room (OR) increases constantly, facilitating the development of intelligent OR systems functioning as “safety backup” in the background of surgery. Precondition is comprehensive data retrieval to identify imminent risky situations and inaugurate adequate security mechanisms. Radio-frequency-identification (RFID) technology may have the potential to meet these demands.

Methods

We set up a pilot study investigating feasibility and appliance reliability of a stationary RFID system for real-time surgical sponge monitoring (passive tagged sponges, position monitoring: mayo-stand/abdominal situs/waste bucket) and OR team tracking (active transponders, position monitoring: right/left side of OR table).

Results

In vitro: 20/20 sponges (100%) were detected on the mayo-stand and within the OR-phantom, however, real-time detection accuracy declined to 7/20 (33%) when the tags were moved simultaneously. All retained sponges were detected correctly. In vivo (animal): 7–10/10 sterilized sponges (70%–100%) were detected correctly within the abdominal cavity. OR-team: detection accuracy within the OR (surveillance antenna) and on both sides of the OR table (sector antenna) was 100%. Mean detection time for position change (left to right side and contrariwise) was 30–60 s. No transponder failure was noted.

Conclusion

This is the first combined RFID system that has been developed for stationary use in the surgical OR. Preclinical evaluation revealed a reliable sponge tracking and correct detection of retained textiles (passive RFID) but also demonstrated feasibility of comprehensive data acquisition of team motion (active RFID). However, detection accuracy needs to be further improved before implementation into the surgical OR.

Introduction

It has been the vision of both surgeons and medical engineers to create intelligent OR systems functioning as “safety backup” in the background of surgery. These systems should not only retrieve data from the procedure [1] but, by online data analysis, be able to interpret whether the course of the operation is normal or deviating from the schedule (“situation awareness”) [2]. However, the implementation of this “intelligent system in the background” in a surgical environment is by far more demanding than under technical or industrial conditions [3]. Data-inflow has to be continuous and comprehensive in real time [4]. Furthermore, data collection must be possible without disrupting the routine course of surgery (“stealth mode”) [1], should not impose additional workload to the team, and simultaneously avoid erroneous perceptions in the high stress environment of the OR.

Radio-frequency-identification (RFID) technology, which was introduced recently in the health care sector, may have the potential to meet these demands. RFID technology is widely available and relatively easy to integrate into the healthcare supply chain [5]. RFID systems use individual transponders (tags), which emit a specific identification signal. Nearby antennas emit radio waves that are absorbed by the tag, converted to electrical energy, and then re-emitted at the tag’s specific frequency [6]. These frequencies are then read by the antennas, creating a real time “inventory” of the controlled sector [7]. This information is then usable by a variety of middleware applications, opening options for “safety” checkpoints, automated workflow protocols, and access control systems [8]. Meanwhile, RFID application has been proven to be effective for patient tracking [9] and reducing or eliminating instances of retained surgical sponges (gossypiboma) [7].

Despite manual counting by OR personnel, the incidence of retained surgical objects is estimated at 1:10,000 cases [10] during open surgical procedures, of which 70% are surgical sponges. Risk factors are emergency operations with unplanned changes in procedure and patients with higher body mass indexes. Estimates suggest that such errors occur in 1 of every 1000–1500 intra-abdominal operations [10]. Main complications are intestinal obstruction, discharching sinus, abscess formation, and peritonitis. In the literature, morbidity rates of up to 40% and mortality rates of 5% are reported [11]. Each case is not only incriminating for the patient, but has also legal and eventually penologic consequences for the surgeon.However, RFID technology is not only suitable for intraoperative textile monitoring [12] but has also been proven to be effective for personnel tracking in hospitals [13]. The dynamics of human motion in the OR comprise key information for surgical workflow description, as presence and absence of OR team members follow a specific order during the course of a procedure reflecting the single steps of the operation. A continuous automated monitoring of the OR team in real-time is therefore not only a precondition for obtaining information of the routine surgical workflow but, furthermore, essential to determine potential deviations. Thereby, implementation of assistance and security mechanisms is achievable in case of unexpected procedure aberrance for increased patients’ safety (e.g., intensive-care unit alert or on-time consultation of specialists) [14].

For proof of concept of RFID implementation in the surgical OR, we set up a pilot study investigating the feasibility and appliance reliability of a stationary RFID system for real-time surgical sponge monitoring (passive RFID) and OR team tracking (active RFID) and herein report the results of our preclinical evaluation. To our best knowledge, this is the first report of a combined passive/active RFID appliance for textile and personnel monitoring in the surgical OR.