Delta mean neutrophil volume (ΔMNV) is comparable to procalcitonin for predicting postsurgical bacterial infection

The Coulter LH750 (Beckman Coulter, Brea, CA) analyzer can determine intrinsic biophysical properties of white blood cell (WBC), known as cell population data. Previous studies have shown that mean neutrophil volume (MNV) was significantly increased in postsurgical patients with bacterial infection. To further validate its potential clinical usefulness, we investigate the changes in MNV before and after surgery, called ΔMNV. We also compare the ΔMNV with procalcitonin (PCT) and C-reactive protein (CRP) in terms of diagnostic sensitivity and specificity for postsurgical bacterial infection.

Blood samples from 300 healthy controls, 219 cardiac surgical patients without postsurgical infection, and 31 cardiac surgical patients complicated with postsurgical bacterial infection were studied.

There are no statistically significant differences for WBC count and neutrophil percentage prior to or after surgery between postsurgical noninfected and infected patients. However, the ΔMNV is significantly increased in postsurgical infected patients when compared with noninfected patients (P < 0.05). The receiver-operating characteristics analysis reveals the ΔMNV and PCT have largest areas under curves (0.92, 0.93 on the second day and 0.94, 0.99 on the third day postsurgery, respectively) compared to other parameters.

ΔMNV shows comparable sensitivity and specificity to PCT and superior sensitivity and specificity to WBC or CRP for predicting postsurgical bacterial infection. The potential clinical application of this parameter merits further exploration in a larger prospective study.