Objective To explore the impact of pre positioned nasopharyngeal airway combined with high head pre inhalation of oxygen on lung oxygenation and blood gas analysis indicators in morbid obese patients undergoing laparoscopic weight loss surgery.Methods 100 morbid obesity patients from January 2020 to April 2022 planned to undergo elective laparoscopic weight loss surgery were selected as the study subjects.All the patients were divided into two groups according to the random number table method:group A with a head height of 25° and a pre installed nasopharyngeal airway;group B with a head height of 25° and no pre installed nasopharyngeal airway,with 50 patients in each group.Two groups were pre oxygenated for 3 min before undergoing intravenous anesthesia to induce tracheal intubation.Observe and record the pH value,partial pressure of oxygen in arterial blood(PaO2),partial pressure of carbon dioxide(PCO2),partial pressure of oxygen in arterial blood/fractional concentration of inspiratory oxygen(PaO2/FiO2)as well as the ratio of arterial pressure to alveolar oxygen partial pressure(a/APO2)of the two groups of patients who breathed air(T0)after entering the room,ventilated with mask positive pressure for 3 min(T1),and intubated with trachea for 3 min(T2).Record plateau pressure(Pplat),peak airway pressure(Ppeak),and dynamic lung compliance(Cdyn)at T1,T2,and 5 min after pneumoperitoneum(T3).Record the time for percutaneous arterial oxygen saturation(SpO2)to decrease to 92.0%under different artificial ventilation after tracheal intubation,the time for SpO2 to recover to 96.0%after resumption of ventilation,and the occurrence of adverse reactions.Results Compared with Group B,at time point T1,Group A showed a decrease in PCO2 and an increase in PaO2,with statistically significant differences(all P<0.05);Compared with T0,at time points T1 and T2,PaO2/FiO2 and PCO2 in the two groups were increased,while a/APO2 decreased(all P<0.05).At T1 time point,Pplat and Ppeak in Group A were lower than those in Group B,while Cdyn was higher than that in Group B,with statistical significance(P<0.05);Compared with T1 time point,at T2 and T3 time point,Pplat and Ppeak in Group A increased,while Cdyn decreased,with statistically significant differences(all P<0.05);Compared with T1,Ppeak increased in B groups at T2 time point(P<0.05),while Pplat and Ppeak increased in T3 time point,and Cdyn decreased in B group,with statistical significance(all P<0.05).Compared with Group B,Group A had a longer time for SpO2 to decrease to 92.0%and a shorter time for SpO2 to recover to 96.0%(P<0.01).Conclusion The combination of pre positioned nasopharyngeal airway and high head pre inhalation of oxygen can effectively improve acute respiratory obstruction during induction of general anesthesia insertion in morbid obesity patients,and extend the duration of no ventilation.