Ventilator-Associated Pneumonia: Comparing Cadaveric Liver Transplant and Non-Transplant Surgical Patients

Ventilator-associated pneumonia is a frequent complication in intensive care surgical patients, particularly those with high severity scores on admission. We studied the incidence and clinical outcome of ventilator-associated pneumonia among patients undergoing major general surgery procedures and those undergoing cadaveric liver transplantation in our hospital. Patients with the intensive care unit stay longer than four days having undergone surgery or transplantation and mechanically ventilated for more than 48 hours were included in the study. Ventilator-associated pneumonia diagnosis was based on a combination of radiological signs (progressive infiltrate on chest radiograph), clinical signs (fever >38.3 °C, leukocytes >12×10(9)/mL) and microbiological data (positive culture from tracheal aspiration >10(5) or bronchoalveolar lavage >104 colonies/mL). Medical records of 1037 patients were reviewed and 157 patients were found to have been mechanically ventilated for more than 48 hours: 62 transplanted and 95 non-transplanted. Only 39 (24.84%) patients matched the criteria for ventilator-associated pneumonia. There were no differences in sex, age, duration of mechanical ventilation, length of stay or outcome between the two groups. However, the main difference was the mean severity score on admission (Simplified Acute Physiology Score II) which was higher among non-transplant patients (42±16 vs. 31±9; p=0.03). Gram-negative bacteria were the leading causative agents (82.03%) and were multidrug-resistant. In the intensive care surgical population, transplantation per se does not seem to increase patient risk for either ventilator-associated pneumonia acquisition or worse outcomes.

Role of NRF2 and reactive aldehydes in acute cellular rejection in liver transplant recipients.

OBJECTIVE: To evaluate the level of oxidative stress and antioxidative response in the transplanted liver and its role in acute cellular rejection (ACR). Particular attention was paid to ACR diagnosis in patients with hepatitis C (HCV), as histopathological features of ACR and viral disease recurrence overlap. METHODS: This retrospective study included 40 liver transplant patients who underwent liver transplantation with two consecutive liver biopsies performed during one hospitalization period: 1.) initial biopsy of the donor liver (before implantation) and 2.) indication biopsy (after suspected ACR). Based on the etiology, patients were divided into two groups: 22 patients with alcoholic liver cirrhosis (EtOH group) and 18 patients with hepatitis C cirrhosis (HCV group). We analyzed the presence of acrolein, HNE (4-hydroxynonenal), and the major antioxidant transcription factor NRF2 (nuclear factor erythroid 2-related factor 2) in both biopsies. RESULTS: The presence of acrolein and HNE in both biopsies indicates increased oxidative stress, while the decrease in these aldehydes in the indication biopsies indicates a decrease in oxidative stress over time, reflecting liver graft recovery. The absence of NRF2 in both biopsies reflects significantly reduced antioxidant protection in patients undergoing liver transplantation. CONCLUSION: The results support the role of oxidative stress in the pathogenesis of ACR. The presence of acrolein and the absence of HNE in the indication biopsy in patients with ACR could contribute to the diagnosis of ACR in clinical practice when functional antibodies are tested in the clinical setting.