Kuhnel was called up by the Astros on Saturday, Chandler Rome of The Athletic reports.
Kuhnel was acquired from the Reds for cash considerations in mid-June. In 74 career major-league innings, he owns a 6.20 ERA and 1.43 WHIP, so he's unlikely to get anywhere near high-leverage work. Ronel Blanco was optioned in a corresponding move.