H. P. Blavatsky

Rechaka. A practice in Hatha Yoga, during the performance of Prânâyâma or the regulation of breath : namely, that of opening one nostril and emitting breath therefrom, and keeping the other closed; one of the three operations respectively called Pûraka, Kumbhaka and Rechaka — operations very pernicious to health.

Source: H. P. Blavatsky, The Theosophical Glossary, art. Rechaka