Correlation between serum lactate and other oxygenation indices as a predictor of outcome in respiratory ICU patients

Abstract

Aim: The objective of the current study is to find out and correlate the predictive value of serum lactate level and other oxygenation indices in the first 24 h of respiratory ICU admission regarding mortality and length of ICU stay. Methods: Thirty three critically ill patients were enrolled. Three samples of lactate and concomitant arterial blood gases (ABG) were obtained. One on admission, one after 12 h and one after 24 h of admission. Results: Twenty patients survived and 13 patients died. A comparison was done between survivors and non survivors regarding oxygen indices and serum lactate. Mean serum lactate was significantly lower in survivors than non survivors in the three samples. In all studied samples, survivors’ group had better oxygen indices in the form of a lower A-a gradient, higher pulse O2 saturation and higher oxygen content but did not reach statistical significance except in sample 3 where A-a gradient was significantly lower in survivors. Mean serum lactate was positively correlated with the length of hospital stay as well as A-a O2 gradient with statistical significant difference. Serum lactate in the three samples was shown to be significantly accurate in predicting non survivors. Cut-off values were 3.76 mmol/L, 3.08 mmol/L, and 2.92 mmol/L respectively; sensitivity 88.9%, 88.9%, and 100% respectively; and specificity 95%, 75%, and 70% respectively. Conclusions: Non survivors had higher blood lactate levels at admission as well as at 12 and 24 h.

Keywords

• Serum lactate
• Oxygenation indices
• Survival