A Potential Mechanism for Immune Suppression by Beta-Adrenergic Receptor Stimulation following Traumatic Injury

Digital Holographic Microscopy for Label-Free Detection of Leukocyte Alternations Associated with Perioperative Inflammation after Cardiac Surgery

In a prospective observational pilot study on patients undergoing elective cardiac surgery with cardiopulmonary bypass, we evaluated label-free quantitative phase imaging (QPI) with digital holographic microscopy (DHM) to describe perioperative inflammation by changes in biophysical cell properties of lymphocytes and monocytes. Blood samples from 25 patients were investigated prior to cardiac surgery and postoperatively at day 1, 3 and 6. Biophysical and morphological cell parameters accessible with DHM, such as cell volume, refractive index, dry mass, and cell shape related form factor, were acquired and compared to common flow cytometric blood cell markers of inflammation and selected routine laboratory parameters. In all examined patients, cardiac surgery induced an acute inflammatory response as indicated by changes in routine laboratory parameters and flow cytometric cell markers. DHM results were associated with routine laboratory and flow cytometric data and correlated with complications in the postoperative course. In a subgroup analysis, patients were classified according to the inflammation related C-reactive protein (CRP) level, treatment with epinephrine and the occurrence of postoperative complications. Patients with regular courses, without epinephrine treatment and with low CRP values showed a postoperative lymphocyte volume increase. In contrast, the group of patients with increased CRP levels indicated an even further enlarged lymphocyte volume, while for the groups of epinephrine treated patients and patients with complicative courses, no postoperative lymphocyte volume changes were detected. In summary, the study demonstrates the capability of DHM to describe biophysical cell parameters of perioperative lymphocytes and monocytes changes in cardiac surgery patients. The pattern of correlations between biophysical DHM data and laboratory parameters, flow cytometric cell markers, and the postoperative course exemplify DHM as a promising diagnostic tool for a characterization of inflammatory processes and course of disease.

Increased risk of catheter-related infection in critically ill patients given catecholamine inotropes during continuous renal replacement therapy

INTRODUCTION

Previous in vitro studies have shown that catecholamine inotropes are potent stimulators of bacterial growth and biofilm formation on catheter surfaces. This study aimed to investigate the effects of administering catecholamine inotropes during continuous renal replacement therapy (CRRT) on catheter-related infections in critically ill patients.

METHODS

This single-center retrospective cohort study included patients requiring CRRT in an intensive care unit from 2016 to 2017, who were divided into those who received and did not receive catecholamine inotropes for ≥24 h (catecholamine and control groups, respectively). The primary endpoint was catheter-related infection, including catheter-related colonization (CRCOL) and catheter-related bloodstream infection (CRBSI).

FINDINGS

We included 235 patients with 297 dialysis catheters. The catecholamine group had higher proportions of cardiovascular disease (p = 0.002), shock (p < 0.001), mechanical ventilation (p < 0.001), and antibiotic use (p = 0.013). There was no significant between-group difference in the CRBSI incidence (5.742 vs. 3.143 events/1000 catheter-days; p = 0.205). However, the CRCOL incidence was significantly higher in the catecholamine group than in the control group (6.221 vs. 0.898 events/1000 catheter-days; p = 0.006). The prominent pathogenic bacteria were gram-negative bacteria. After adjusting for confounding factors in multivariate logistic models, catecholamine inotropes (OR: 3.575, 95% CI: 1.422-9.912, p = 0.008) and immunosuppression (OR: 2.980, 95% CI: 1.137-7.812, p = 0.026) were independently associated with a higher risk of catheter-related infections.

DISCUSSION

We observed a similar incidence of catheter-related infection with that in other CRRT patients. Using catecholamine inotropes in those patients increased CRCOL risk, which is consistent with previous in vitro studies. Our findings suggest that catecholamine inotropes is an independent risk factor for catheter-related infections in critically ill patients undergoing CRRT.