Defibtech expects to complete a software correction in 42,000 semi-automatic external defibrillators this month as it works to distribute the upgrades to customers.

Three field reports of device failures resulting from a software glitch prompted the firm to initiate a Class I recall in February. The glitch allowed the devices’ internal low-battery detection system to clear a previous low-battery warning, making it so operators were unaware of a low-battery condition. The firm began shipping the software updates to customers in April.

Following the initiation of the recall, the FDA inspected Defibtech’s Guilford, Conn, facility and followed up with a warning letter. The letter can be accessed on the FDA Web site.