1. Every individual receiving a general anesthetic is at potential risk for developing a ''cannot intubate-cannot ventilate'' situation following anesthetic induction.
2. Building up of oxygen reserves assumes great significance as this provides a longer duration of non-hypoxic apnea should one be faced with an unanticipated difficult airway.
3. The main physiological functions of red blood cell hemoglobin are to deliver oxygen to the peripheral tissues.
4. During anemia, a reduction in blood oxygen content occurs as a result of reduced Hb while arterial oxygenation and oxyhemoglobin saturation remain high.
5. Previous studies about the duration of non-hypoxic apnoea focus on methods to improve the safety period of tracheal intubation.
6. To our knowledge, there is no literature about the duration of non-hypoxic apnoea of anemia patients.
7. The aim of this study was to assess the effect of chronic anemia on the duration of non-hypoxic apnoea during induction of anaesthesia.

After breathing for 3 minutes, anesthesia induction was conducted. The endotracheal tube position was confirmed after anesthesia induction. Patients were left apneic with the endotracheal tube open to room air. The non-hypoxic apneic period was recorded as the time (in seconds) taken for the drop in pulse saturation to 90% or an apneic period of 10 min elapsed, whichever was earlier.

Inclusion Criteria:

1. patients scheduled to undergo general anesthesia
2. American Society of Anesthesiologists Performance Status 1-2
3. adults

Exclusion Criteria:

1. Individuals with significant cardiorespiratory or cerebrovascular disease,
2. difficult intubation
3. history of epilepsy
4. body mass index >25 kg/m2,
5. and those who had smoking history in past 6 months