The present disclosure relates to a method and a mechanical ventilation system for adjusting a level of ventilatory assist to a patient. A neuro-mechanical efficiency of the patient is determined. A control value is received at the mechanical ventilation system. The level of ventilatory assist to the patient is determined on the basis of the neuro-mechanical efficiency and of the control value. The mechanical ventilation system may be adjusted automatically based on the determined level of ventilatory assist to the patient. Alternatively, the determined level of ventilatory assist to the patient may be displayed for the benefit of an operator and a manual command may be received for adjusting the mechanical ventilation system.