Refeeding syndrome (RFS) is a potentially life-threatening complication in malnourished (critically ill) patients. The presence of various accepted RFS definitions and the inclusion of heterogeneous patient populations in the literature has led to discrepancies in reported incidence rates in patients requiring treatment at an intensive care unit (ICU). We conducted a prospective observational study from 2010 to 2013 to assess the RFS incidence and clinical characteristics among medical ICU patients at a large tertiary center. RFS was defined as a decrease of more than 0.16 mmol/L serum phosphate to values below 0.65 mmol/L within seven days after the start of medical nutrition therapy or pre-existing serum phosphate levels below 0.65 mmol/L. Overall, 195 medical patients admitted to the ICU were included. RFS was recorded in 92 patients (47.18%). The presence of RFS indicated significantly altered phosphate and potassium levels and was accompanied by significantly more electrolyte substitutions (phosphate, potassium, and magnesium). No differences in fluid balance, energy delivery, and insulin requirements were detected. The presence of RFS had no impact on ICU length of stay and ICU mortality. Screening for RFS using simple diagnostic criteria based on serum phosphate levels identified critically ill patients with an increased demand for electrolyte substitutions. Therefore, stringent monitoring of electrolyte levels is indicated to prevent life-threatening complications.

Invasive fungal infections are a major cause of morbidity and mortality in immunocompromised and critically ill patients. While plasma pharmacokinetics (PK) commonly guide antifungal dosing, they may not reliably reflect drug exposure at infection sites, particularly in compartments that are difficult to reach. Tissue PK is increasingly recognised as an important determinant of optimal dosing and therapeutic success. This review summarises available clinical data on tissue PK of approved antifungal agents, including triazoles, echinocandins, amphotericin B formulations, and flucytosine. Studies were identified via a PubMed search through July 2025, focusing on prospective human trials reporting both plasma and tissue concentrations. Our findings revealed marked variability in tissue penetration across drugs and compartments. These findings underscore the limitations of relying solely on plasma concentrations to estimate tissue exposure and emphasise the importance of considering tissue penetration when selecting and dosing antifungal therapy.

Background: Gastrointestinal dysfunction is a common complication of medical nutrition therapy in critically ill patients. Whether prone positioning leads to a deterioration in gastrointestinal function has not been fully clarified. Thus, we aimed to analyze the influence of prone positioning on the tolerance of medical nutrition therapy. Methods: We conducted a retrospective analysis of 102 SARS-CoV-2 infected patients with venovenous extracorporeal membrane oxygenation support (VV ECMO). Gastric residual volume (GRV) was used to assess the tolerance of enteral nutrition. Results: Nutritional data were collected for 2344 days. Undernutrition was observed in 40.8%, with a significantly higher incidence on days in prone position (48.4% versus 38.6%, p < 0.001). On days in supine position, significantly more calories were administered enterally than on days in prone position (p < 0.001). The mean GRV/24 h was 111.1 mL on days in supine position and 187.3 mL on days in prone position (p < 0.001). Prone positioning was associated with higher rates of GRV of ≥500 mL/24 h independent of age, disease severity at ECMO start, ECMO runtime and ICU length of stay (adjusted hazard ratio: 4.06; 95%CI: 3.0–5.5; p < 0.001). Conclusions: Prone position was associated with lower tolerance of enteral nutrition, as indicated by an increased GRV. As a result, reduced enteral nutritional support was administered.

Treatment of acute respiratory distress syndrome (ARDS) represents a severe complication of coronavirus disease 2019 (COVID-19) infection and is often challenging in intensive care treatment. Potential positive effects of intravenous cyclophosphamide have been reported in interstitial lung diseases (ILDs). However, there are no data on the use of high-dose cyclophosphamide in therapy-resistant COVID-19 ARDS. We report the case of a 32-year-old male patient admitted to the intensive care unit (ICU) of the Medical University of Vienna due to severe COVID-19 ARDS who required venovenous extracorporeal membrane oxygenation (ECMO) with a total runtime of 85 days. Despite all these therapeutic efforts, he remained in a condition of therapy-resistant ARDS. Unfortunately, the patient was denied for lung transplantation. However, a significant improvement in his respiratory condition was achieved after the administration of an intravenous regimen of cyclophosphamide and prednisolone. After a period of consecutive stabilization, the patient was transferred to the normal ward after 125 days of intensive care treatment. There is a substantial lack of therapeutic options in therapy-resistant ARDS. Our case report suggests that cyclophosphamide may represent a new treatment strategy in therapy-resistant ARDS. Due to its severe adverse effect profile, cyclophosphamide should be used after careful evaluation of a patient’s general condition.

Background/Objectives: Refeeding syndrome (RFS) is a potentially life-threatening complication of nutritional support in critically ill patients. Its incidence and clinical relevance in patients requiring extracorporeal membrane oxygenation (ECMO) are unknown. We retrospectively investigated the incidence, characteristics and clinical relevance of RFS in COVID-19 patients receiving venovenous (vv-)ECMO support. Methods: In a secondary analysis of 101 COVID-19 patients treated with vv-ECMO at a tertiary center, RFS was defined by a decrease of more than 0.16 mmol/L in serum phosphate to a value below 0.65 mmol/L within seven days of starting medical nutrition therapy (MNT), or a pre-existing phosphate below 0.65 mmol/L. Electrolyte trajectories, nutritional delivery, predictors of RFS, and the association with ICU mortality were analyzed. Robustness was assessed across alternative published definitions. Results: RFS developed in 46 of 101 patients (45.5%), with an incidence ranging from 23.8% to 84.2% depending on the definition applied. Patients with RFS had a lower body mass index and required significantly more phosphate substitution than those without (93.5% vs. 43.6%; p < 0.001). Early energy delivery did not differ between groups and was not associated with RFS. RFS was not associated with ICU mortality (41.3% vs. 41.8%; adjusted hazard ratio 0.80, p = 0.51), a finding consistent across all definitions examined. Conclusions: In this COVID-19 vv-ECMO cohort, refeeding-associated hypophosphatemia was frequent but not associated with caloric delivery or ICU mortality under close electrolyte monitoring. These hypothesis-generating findings do not support reducing caloric intake for isolated hypophosphatemia and require prospective confirmation.