Three drops of peppermint oil will be dropped on a cotton ball that will be fixed in the patient's collar. In the placebo group, peppermint oil will be replaced with water.

Mechanical ventilathetion increases the anxiety of critically ill patients. The physiological parameters of those patients are affected by stress. Peppermint inhalation reduces stress and improves physiological parameters in many studies, but none of these studies used peppermint inhalation on mechanically ventilated patients.

Patients who are conscious on mechanical ventilation via endotracheal via tube will be randomly assigned to two groups. Patients will be kept intubated and mechanically ventilated. Nothing will be changed in patients' mechanical ventilation data. The intervention group will receive peppermint inhalation intervention, and the placebo group received water inhalation intervention. Patients in both groups will be assessed for their smell ability by Sniffin Sticks-test before starting the interventions.

Three drops of undiluted peppermint oil will be dropped on a cotton ball. Then it will be placed about 20 cm from the patient's nose. It will be fixed on the patient's collar. In the placebo group, the cotton ball will be soaked in water. Then, patients will be monitored for one hour.

Inclusion Criteria: Patients with

• (1) endotracheal tube (ETT)
• (2) mechanical ventilation with spontaneous breathing modes which are CPAP, PIPAP and PSV
• (3) FOUR score equal to or more than 13,
• (4) RASS score from -1 to +4.

Exclusion Criteria: Patients with

• (1) respiratory asthma
• (2) chronic obstructive pulmonary disease
• (3) acute respiratory distress syndrome,
• Sniffin' Sticks-test score of smell less than 17

No sharing of the patient data was planned