Tanzeela Firdous, Ali Kashif, Sahira Nawaz Khan, Ayesha Waqar, Sufyan Ali, Sumayya Tariq 2022. Compare the Mean Non Hypoxic Apnea Duration of 20° Head up with Conventional Supine Position during Pre-oxygenation in Patients Undergoing Elective Surgery. Pakistan Journal of Medical & Health Sciences. 16, 07 (Aug. 2022), 397. DOI:https://doi.org/10.53350/pjmhs22167397.