He was re-appointed last year after Deby won a fresh five-year term at elections boycotted by the opposition in the impoverished, landlocked central African state.
Despite becoming one of Africa's most recent oil producers, Chad remains near the bottom of the continent's development indices.
Deby's government faces a low-intensity conflict with rebels in eastern Chad as well as ethnic conflict spilling across the border from the neighbouring Sudanese region of Darfur.
The fighting has displaced tens of thousands of Chadians.
When Yoadimnadji was admitted to hospital on Friday, government sources said the infrastructure minister, Adoum Younousmi would take over as the interim head of the cabinet.