The Kiwi was set to test for HMD Motorsport at Sebring today (US time) to ramp up preparations for his rookie season in the IndyCar feeder series.
However he instead ended up in hospital with a case of appendicitis – and underwent surgery to have his appendix removed.
Indy NXT hardware isn't totally foreign to Hedge, who tested for Cape Motorsports on the Indianapolis road course last October.
His 2024 drive comes as part of a Honda scholarship he received for winning the Formula Regional Americas title last year.
He dovetailed that programme with Carrera Cup Australia, also winning that title (despite missing a a round) after a thrilling showdown in Adelaide.
The 2024 Indy NXT season kicks off in St Petersburg in March.