The FDA has issued a warning letter to BMC Medical Co., Ltd., the Beijing-based manufacturer behind the Luna and G3X lines of CPAP and APAP devices sold in the U.S. through distributor 3B Medical (doing business as React Health) of Dublin, Ohio. The letter, dated May 20, 2026, stems from an FDA inspection of 3B Medical’s Dublin facility conducted December 1–10, 2025, and follows a companion warning letter issued the same day to 3B Medical itself.
At the center of the action is the G3X APAP (model G4600), which FDA investigators determined is not simply a variant of BMC’s already-cleared Luna CPAP and Auto CPAP System (K153387, cleared September 8, 2016) but a materially different device marketed without its own 510(k) clearance, PMA approval, or IDE. Under sections 501(f)(1)(B) and 502(o) of the Food, Drug and Cosmetic Act, that combination renders the G3X both adulterated and misbranded.
What Changed Under the Hood
FDA’s review of BMC’s own design-change documentation — including a design change evaluation report for the Luna G3 APAP (model LG3600), approved internally in March 2025 — found the company had layered in several changes it never brought back to the agency:
A firmware update added three new detection algorithms: flow limitation, respiratory effort-related arousal (RERA), and periodic breathing, specifically to differentiate central from obstructive hypopnea events. FDA flagged this as directly affecting the accuracy of event classification and, by extension, the therapy-effectiveness data clinicians rely on to titrate care.
The sound abatement system was reworked, with a redacted material removed from the design and a new redacted component added to preserve noise reduction — a change FDA characterized as a modification to the gas pathway with potential biocompatibility implications, and one that, combined with the added component, could alter the device’s pressure and flow delivery profile.
The printed circuit board assembly picked up a new chip paired with a new algorithm and data structure for the master control software, which FDA said carries its own electrical safety and performance implications.
Taken together, the agency wrote, these are “significant modifications in device design, materials, and software that could significantly affect the safety and effectiveness of the device” — the standard that triggers a new 510(k) under 21 CFR 807.81(a)(3)(i). FDA’s letter points BMC toward its guidance on when device changes require a new submission, and suggests the company use the Q-Submission program to get agency feedback before resubmitting for the G3X.
A Separate Reporting Failure
The letter also cites a corrections-and-removals violation under section 502(t)(2). FDA says BMC’s Luna G3 APAP units running firmware G3-2.00.76 were subject to unexpected shutdowns during use — a loss-of-therapy risk for patients being treated for obstructive sleep apnea. BMC pushed a corrective firmware update, G3-2.00.77, but as of May 19, 2026, had not filed the Report of Correction or Removal required within 10 working days of initiating that correction, per 21 CFR Part 806 and 21 CFR 806.10.
Response and Context
FDA has given BMC 15 business days from receipt to detail corrective actions or to contest the findings in writing. The letter also notes that while the underlying inspection was conducted under the prior Quality System Regulation, any corrective action BMC now implements must conform to the Quality Management System Regulation (QMSR), which took effect February 2, 2026.
For clinicians and sleep labs currently dispensing Luna or G3X-branded devices, the letter’s substance is worth flagging internally: the algorithmic distinction FDA describes — separating central from obstructive hypopnea — goes directly to how therapy data from these devices should be interpreted, and the unresolved shutdown issue on G3-2.00.76 firmware is a patient-facing reliability concern independent of the regulatory question. Neither this warning letter nor the companion letter to 3B Medical constitutes a recall; no mandatory field action has been ordered as of this writing.
Written by SleepWorld Magazine staff.
Source: FDA Warning Letter, BMC Medical Co., Ltd., MARCS-CMS 725759, May 20, 2026.
