<prompt> Macintosh indicator is used for ?To assess degree of NM blockadeLocalization of extradural spaceTo assess level of GATo monitor respiratory depression  <response>: Ans. is b i.e., Localization of extradural space Various methods have been used to locate the epidural extra dural space, most of which rely on subatmospheric pressure. These are :- Loss of resistance to air or saline most common technique. Gutierrezs method : A hanging drop of saline on the hub of needle is drawn in as the epidural space is entered more reliable in thorocic than lumbar region. Odom s indicator : A fine-bore glass tube filled with saline and a bubble that moves in response to a drop in pressure. Macintoshs indicator : A small rubber balloon filled with air connected to an adaptor causing it to deflate on entering the epidural space. Macintoshs spring-loaded needle. Ultrasonic localization. Oxford epidular space detector. 