Abstract:

Objective To find out the reasons for high positive rate of blood lactic acid and ammonia determination results among the inpatients in Tongji Hospital affiliated to Tongji University,and to take measures to improve the accuracy of blood lactic acid and ammonia determination results. Methods With blood lactic acid >2.2 mmol/L and blood ammonia >30 μmol/L indicating positive results,the total number and positive rate of blood lactic acid and ammonia determinations and the time used for each link in the determination process in the outpatient,emergency,inpatient and inpatient emergency departments were calculated from January to June 2019. Totally,40 clinical samples were collected randomly,and blood lactic acid and ammonia were determined at 15,30,45,60,90,120 and 180 min after sample collection. With the results at 15 min as the baseline values,the deviation between the means of the results at the subsequent time points and the baseline values was calculated. After improvement measures were formulated and implemented,the positive rate of blood lactic acid and ammonia determination results was calculated,and the changes in the time used for each link in the determination process were compared. Results The positive rates of blood lactic acid determinations were 36.87%,50.73%,58.28% and 84.44%,and those of blood ammonia determinations were 14.68%,13.48%,34.04% and 72.67% in the outpatient,emergency,inpatient and inpatient emergency departments from January to June 2019,respectively. The median times from sample collection to determination on machines were 35,32,130 and 83 min in the outpatient,emergency,inpatient and inpatient emergency departments,respectively. The deviations between the results and the baseline values of blood lactic acid and ammonia determination increased gradually over time in the 40 clinical samples. After the improvement of determination process,the positive rates decreased to 32.59% and 22.65% for blood lactic acid and ammonia determination results,respectively. The time used from sample collection to determination on machines was shortened to 43 min. Conclusions Through the optimization of pre-determination process,the time used from sample collection to determination on machines can be reduced effectively,so that the positive rates of blood lactic acid and ammonia determination results are decreased with improved accuracy.

Key words: Blood lactic acid, Blood ammonia, Determination quality, Process optimization