Is EC integrated encryption scheme used in practice? I know ECDSA and ECDH are used a lot but what about the ECIES? Is it used or specified as an option in any protocol?
Yes, ECIES is used in practice. That's the simplest way (thus arguably the best) to establish a key or/and encipher using Elliptic Curve Cryptography in contexts including unidirectional data transfer, or data-at-rest like backup with encryption under public key.

As an illustration, it is often listed in the Other algorithms section of FIPS-140-validated cryptographic devices; I count like 28 occurrences.

ECIES is in the de-facto standard SEC&nbsp;1, IEEE&nbsp;Std&nbsp;1363a-2004, and ANSI&nbsp;X9.63-2011. It is used e.g. in Intelligent Transport Systems as specified by ETSI&nbsp;TS&nbsp;103&nbsp;097. The similar ECIES-KEM is in ISO/IEC&nbsp;18033-2:2006 following a well-documented proposal by Victor Shoup.