Macro, and microcirculatory effects of crystalloids and colloids are difficult to compare, because interventions to achieve haemodynamic stability seldom follow similar criteria. Our aim was to compare the effects of crystalloids and colloids on the microcirculation during free flap surgery when management was guided by detailed haemodynamic assessment. A randomised, controlled clinical trial. The investigation was performed at the University of Szeged, Hungary. Patients undergoing maxillofacial tumour resection and free flap reconstruction were randomised into groups treated with either intra-operative crystalloid (Ringerfundin, n = 15) or colloid (6% hydroxyethyl starch, HES, n = 15) solutions. Macrohaemodynamics were monitored by a noncalibrated device (PulsioFlex-PULSION). Central venous oxygen saturation, venous-to-arterial PCO2-gap, lactate levels and urine output were measured hourly. Maintenance fluid was Ringerfundin (1 ml kg−1 h−1), and a multimodal, individualised, approach-based algorithm was applied to guide haemodynamic support. Hypovolaemia was treated with Ringerfundin or HES fluid boluses, respectively. The microcirculatory effects were assessed by laser-Doppler flowmetry (PeriFlux 5000 LDPM), with the probe placed on the flap and on a control area. Measurements were performed after the flap was prepared, then 1 and 12 h later. The primary end-point was microcirculatory perfusion as determined by laser-Doppler flowmetry. There was no difference between the groups regarding patient characteristics. Both groups remained haemodynamically stable throughout due to the use of approximately a 1.5 times higher total fluid volume in the Ringerfundin group than in the HES group: mean ± SD: 2581 ± 986 and 1803 ± 497) ml, respectively, (P = 0.011). There was no significant difference in the microcirculatory blood flow between the groups. Our results showed that when fluid management was guided by detailed haemodynamic assessment, more crystalloid than colloid was needed to maintain haemodynamic stability, but there was no difference between the effects of crystalloids and colloids on the microcirculation. ClinicalTrials.gov NCT03288051.

Purpose. To investigate whether absolute value of procalcitonin (PCT) or the change (delta-PCT) is better indicator of infection in intensive care patients.Materials and Methods.Post hocanalysis of a prospective observational study. Patients with suspected new-onset infection were included in whom PCT, C-reactive protein (CRP), temperature, and leukocyte (WBC) values were measured on inclusion (t0) and data were also available from the previous day (t-1). Based on clinical and microbiological data, patients were groupedpost hocinto infection- (I-) and noninfection- (NI-) groups.Results. Of the 114 patients, 85 (75%) had proven infection. PCT levels were similar att-1: I-group (median [interquartile range]): 1.04 [0.40–3.57] versus NI-group: 0.53 [0.16–1.68],p=0.444. Byt0PCT levels were significantly higher in the I-group: 4.62 [1.91–12.62] versus 1.12 [0.30–1.66],p=0.018. The area under the curve to predict infection for absolute values of PCT was 0.64 [95% CI = 0.52–0.76],p=0.022; for percentage change: 0.77 [0.66–0.87],p<0.001; and for delta-PCT: 0.85 [0.78–0.92],p<0.001. The optimal cut-off value for delta-PCT to indicate infection was 0.76 ng/mL (sensitivity 80 [70–88]%, specificity 86 [68-96]%). Neither absolute values nor changes in CRP, temperature, or WBC could predict infection.Conclusions. Our results suggest that delta-PCT values are superior to absolute values in indicating infection in intensive care patients. This trial is registered with ClinicalTrials.gov identifier:NCT02311816.

The physiology of the kidney has long been understood, and its mechanisms are well described. The pathology of renal failure is also a deeply researched area. It seems logical, therefore, to create devices that can replace the lost normal function of the kidney. Using the physical processes that take place in the kidney, such as diffusion or convection across a membrane, various renal replacement therapies (RRT) have been created. There are those that are used intermittently and those that are used for longer periods. What they have in common is that all RRTs have the same purpose; to replace the excretory function of the kidney that has been lost. CRRT is an extracorporeal renal replacement therapy that effectively replicates the excretory function of the kidneys in cases of acute renal failure. However, it has become increasingly evident that this rapidly advancing treatment modality offers benefits beyond merely substituting kidney function, with its applications continuing to expand significantly with non-renal and other indications. The use of these devices has raised new questions, many of which are still not clearly answered. When should this start? Who should receive it? How long should it last? What indication should it be for? What modality should it be with? How does it change the pharmacokinetics of the medicines? To answer these questions, it is first worth understanding the mechanisms behind the processes and the factors that influence them. This should not only focus on the procedures used in RRT therapies, but also consider the patient’s condition and the physicochemical properties of the drugs. In this review, we aim to provide a literature summary to highlight the factors that may influence the success of RRT therapies.