A diaphragm respiratory signal simulator is activated by skin voltage that is coupled to the simulator by many ways such as but not limited to a user sliding a finger over a conductive surface, the user sliding a finger over surfaces close to the conductive element, touch or sliding the finger over the ventilator screen. The conductive surface is electrically connected to a ring electrode at a distal part of a manikin's esophagus. The diaphragm respiratory signal simulator produces a synthetic diaphragm electrical signal that triggers a ventilator to deliver a supported breath, which is proportional to the strength of the generated signal. This process allows safe and successful training on the operations of NAVA mode of ventilation and catheter positioning.