Background: We performed a prospective, randomized, placebo-controlled study aimed to evaluate the efficacy and safety of a sedation protocol based on intranasal Ketamine and Midazolam (INKM) administered by a mucosal atomizer device in uncooperative children undergoing gastric aspirates for suspected tuberculosis., Primary Outcome: evaluation of Modified Objective Pain Score (MOPS) reduction in children undergoing INKM compared to the placebo group., Secondary Outcomes: evaluation of safety of INKM protocol, start time sedation effect, duration of sedation and evaluation of parents and doctors' satisfaction about the procedure., Methods: In the sedation group, 19 children, mean age 41.5 months, received intranasal Midazolam (0.5 mg/kg) and Ketamine (2 mg/kg). In the placebo group, 17 children received normal saline solution twice in each nostril. The child's degree of sedation was scored using the MOPS. A questionnaire was designed to evaluate the parents' and doctors' opinions on the procedures of both groups., Results: Fifty-seven gastric washings were performed in the sedation-group, while in the placebo-group we performed 51 gastric aspirates. The degree of sedation achieved by INMK enabled all procedures to be completed without additional drugs. The mean duration of sedation was 71.5 min. Mean MOPS was 3.5 (range 1-8) in the sedation-group, 7.2 (range 4-9) in the placebo-group (p <0.0001). The questionnaire revealed high levels of satisfaction by both doctors and parents in the sedation-group compared to the placebo-group. The only side effect registered was post-sedation agitation in 6 procedures in the sedation group (10.5%)., Conclusions: Our experience suggests that atomized INKM makes gastric aspirates more acceptable and easy to perform in children., Trial Registration: Unique trial Number: UMIN000010623; Receipt Number: R000012422.