Articles 
TO THE EDITOR
Figure 1. When the plunger is pulled back to the stop (black arrow), the plunger tip is located at the numeral 8 (white arrow).
The Perifix® L.O.R. syringe (B-Braun, Melsungen, Germany) is designed to be used with the loss of resistance (LOR) technique to confirm the epidural space.1 The syringe is designed to slide easily by minimizing the contact area between the barrel and the plunger. To prevent the plunger from being withdrawn out of the barrel when retracted, there is a stop built into the syringe at the back of the barrel. When the plunger is pulled back to the stop (Fig. 1 black arrow), the plunger tip is located at the numeral 8 (Fig. 1 white arrow). However, we are able to retract the plunger past the stop by applying a slightly stronger force. Once the plunger is retracted past the stop, it is not possible to push the plunger back into the barrel easily, because this syringe is not designed to retract the plunger past the stop. Thus, if the syringe is used to detect the epidural space after the plunger has been retracted past the stop, there is a risk of accidental dural puncture because the LOR will not occur even though the needle tip reaches the epidural space.
Tatsumi Yakushiji, MD
Physician in Department of Anesthesiology at the Fukushima Medical University, Fukushima, Fukushima, Japan
Keisuke Yoshida, MD
Physician in Department of Anesthesiology at the Fukushima Medical University, Fukushima, Fukushima, Japan
Takayuki Hasegawa, MD
Physician in Department of Anesthesiology at the Fukushima Medical University, Fukushima, Fukushima, Japan
Satoki Inoue, MD
Professor of Anesthesiology at the Fukushima Medical University, Fukushima, Fukushima, Japan
The authors have no conflict of interest.
REFERENCES
- Brull R, MacFarlane AJR, Chan VWS. Spinal, epidural, and caudal anesthesia. In: Gropper MA, editor. Miller’s anesthesia. 9th ed. Elsevier; 2020. p.1413-1449.