Abstract： Objective To examine the effect of a newly-developed tracheal detecting-bulb (TDB) in preventing the spray of contaminants in patients' exhalent during emergency endotracheal intubation procedure.Methods 62 emergency patients (male or female,age 21 - 73 years,weight 47 - 83 kg,with different levels of consciousness and spontaneous breathing) were randomly divided into two groups (n=31 each) to receive endotracheal intubation by an anesthesiologist with more than 17 years of experience,with (TDB group) or without (control group) a TDB connected to the tracheal tubing.Records were taken regarding the patient's coughing,expansion/contraction of the TDB,the operator's feeling of the patient's exhalent on his face/neck and the contamination of these areas by blood/secrations from the patients in the due course.Results In TDB group,expansion/contraction of TDB occurred in all cases,but the operator felt no exhalent in any of them.In 9 cases the patients coughed but the operator was contaminated only in 2 cases.While in control group,the patients' exhalent was felt in 16 cases.Coughing were recorded in 7 cases,and the operator was contaminated in 11 cases.In comparison with the control group,TDB group had significantly lower (both P＜0.05) incidence in feeling the exhalent (0 vs.16),and contamination by blood or secretions (2 vs.11) although the two groups had no significant difference in the incidence of coughing (9 vs.7,P ＞ 0.05 ).Conclusion TDB can play an important role in blocking the spray of contaminants in patients' exhalent during endotracheal intubation.