A Role of Circuit Clotting and Strategies to Prevent It during Blood Purification Therapy with oXiris Membrane: An Observational Multicenter Study.

INTRODUCTION: Membrane fouling is a significant complication potentially reducing clinical effects of extracorporeal blood purification (EBP) in critically ill septic patients with acute kidney injury. Although fascinating, the effect of heparin coating in preventing membrane fouling is currently unknown. This multicenter prospective study aims to preliminary describe the incidence, associated factors, and clinical consequences of premature circuit clotting in a cohort of adult critically ill septic patients treated with EBP using a high biocompatible heparin-coated hemodiafilter characterized by advanced adsorption properties. METHODS: This study was a retrospective analysis of prospectively entered data in the oXirisNet Registry; overall, 97 septic patients undergoing EBP with oXiris between May 2019 and March 2020 were enrolled in this study. Patients were divided into two groups according to the occurrence of filter clotting (premature vs. nonpremature). Logistic regression analysis was used to identify factors associated with premature circuit clotting. RESULTS: Premature clotting occurred in 18 (18.6%) patients. Results of the multivariate logistic regression analysis demonstrated that hematocrit (p = 0.02, odds ratio [OR] 1.15 [1.05; 1.30]), serum procalcitonin (PCT) (p = 0.03, OR 1.1 [1.05; 1.2]), and anticoagulation strategy (p = 0.05 at Wald's test) were independent predictors of circuit clotting. Systemic anticoagulation (p = 0.02, OR 0.03 [0.01; 0.52]) and regional citrate anticoagulation (p = 0.10, OR 0.23 [0.04; 1.50]) were both protective factors if compared to no-anticoagulation strategy. Patients with nonpremature circuit clotting showed more rapid recovery from hemodynamic instability, pulmonary hypo-oxygenation, and electrolyte disorders and greater improvement of inflammatory markers and SOFA scores. CONCLUSION: Although in this study the incidence of premature circuit clotting was relatively low (18.6%) compared to previously reported values (54%), membrane clotting in adult critically ill septic patients could cause clinically relevant interferences with treatment performances. Prevention of clotting should be based on avoiding higher patients' hematocrit, high serum PCT, and no-anticoagulation strategy which resulted as independent predictors of circuit clotting.

Methods for dose quantification in continuous renal replacement therapy: Toward a more precise approach.

Periodic dose assessment is quintessential for dynamic dose adjustment and quality control of continuous renal replacement therapy (CRRT) in critically ill patients with acute kidney injury (AKI). The flows-based methods to estimate dose are easy and reproducible methods to quantify (estimate) CRRT dose at the bedside. In particular, quantification of effluent flow and, mainly, the current dose (adjusted for dialysate, replacement, blood flows, and net ultrafiltration) is routinely used in clinical practice. Unfortunately, these methods are critically influenced by several external unpredictable factors; the estimated dose often overestimates the real biological delivered dose quantified through the measurement of urea clearance (the current effective delivered dose). Although the current effective delivered dose is undoubtedly more precise than the flows-based dose estimation in quantifying CRRT efficacy, some limitations are reported for the urea-based measurement of dose. This article aims to describe the standard of practice for dose quantification in critically ill patients with AKI undergoing CRRT in the intensive care unit. Pitfalls of current methods will be underlined, along with solutions potentially applicable to obtain more precise results in terms of (a) adequate marker solutes that should be used in accordance with the clinical scenario, (b) correct sampling procedures depending on the chosen indicator of transmembrane removal, (c) formulas for calculations, and (d) quality controls and benchmark indicators.

Recent advances in cardiorespiratory monitoring in acute respiratory distress syndrome patients.

BACKGROUND: Recent advances on cardiorespiratory monitoring applied in ARDS patients undergoing invasive mechanical ventilation and noninvasive ventilatory support are available in the literature and may have potential prognostic implication in ARDS treatment. MAIN BODY: The measurement of oxygen saturation by pulse oximetry is a valid, low-cost, noninvasive alternative for assessing arterial oxygenation. Caution must be taken in patients with darker skin pigmentation, who may experience a greater incidence of occult hypoxemia. Dead space surrogates, which are easy to calculate, have important prognostic implications. The mechanical power, which can be automatically computed by intensive care ventilators, is an important parameter correlated with ventilator-induced lung injury and outcome. In patients undergoing noninvasive ventilatory support, the use of esophageal pressure can measure inspiratory effort, avoiding possible delays in endotracheal intubation. Fluid responsiveness can also be evaluated using dynamic indices in patients ventilated at low tidal volumes (< 8 mL/kg). In patients ventilated at high levels of positive end expiratory pressure (PEEP), the PEEP test represents a valid alternative to passive leg raising. There is growing evidence on alternative parameters for evaluating fluid responsiveness, such as central venous oxygen saturation variations, inferior vena cava diameter variations and capillary refill time. CONCLUSION: Careful cardiorespiratory monitoring in patients affected by ARDS is crucial to improve prognosis and to tailor treatment via mechanical ventilatory support.

Impact of mechanical power and positive end expiratory pressure on central vs. mixed oxygen and carbon dioxide related variables in a population of female piglets.

INTRODUCTION: The use of the pulmonary artery catheter has decreased overtime; central venous blood gases are generally used in place of mixed venous samples. We want to evaluate the accuracy of oxygen and carbon dioxide related parameters from a central versus a mixed venous sample, and whether this difference is influenced by mechanical ventilation. MATERIALS AND METHODS: We analyzed 78 healthy female piglets ventilated with different mechanical power. RESULTS: There was a significant difference in oxygen-derived parameters between samples taken from the central venous and mixed venous blood (S v ¯ $$ \overline{v} $$ O2 = 74.6%, ScvO2 = 83%, p < 0.0001). Conversely, CO2-related parameters were similar, with strong correlation. Ventilation with higher mechanical power and PEEP increased the difference between oxygen saturations, (Δ[ScvO2-S v ¯ $$ \overline{v} $$ O2 ] = 7.22% vs. 10.0% respectively in the low and high MP groups, p = 0.020); carbon dioxide-related parameters remained unchanged (p = 0.344). CONCLUSIONS: The venous oxygen saturation (central or mixed) may be influenced by the effects of mechanical ventilation. Therefore, central venous data should be interpreted with more caution when using higher mechanical power. On the contrary, carbon dioxide-derived parameters are more stable and similar between the two sampling sites, independently of mechanical power or positive end expiratory pressures.

Estimation of normal lung weight index in healthy female domestic pigs.

INTRODUCTION: Lung weight is an important study endpoint to assess lung edema in porcine experiments on acute respiratory distress syndrome and ventilatory induced lung injury. Evidence on the relationship between lung-body weight relationship is lacking in the literature. The aim of this work is to provide a reference equation between normal lung and body weight in female domestic piglets. MATERIALS AND METHODS: 177 healthy female domestic piglets from previous studies were included in the analysis. Lung weight was assessed either via a CT-scan before any experimental injury or with a scale after autopsy. The animals were randomly divided in a training (n = 141) and a validation population (n = 36). The relation between body weight and lung weight index (lung weight/body weight, g/kg) was described by an exponential function on the training population. The equation was tested on the validation population. A Bland-Altman analysis was performed to compare the lung weight index in the validation population and its theoretical value calculated with the reference equation. RESULTS: A good fit was found between the validation population and the exponential equation extracted from the training population (RMSE = 0.060). The equation to determine lung weight index from body weight was: [Formula: see text] At the Bland and Altman analyses, the mean bias between the real and the expected lung weight index was - 0.26 g/kg (95% CI - 0.96-0.43), upper LOA 3.80 g/kg [95% CI 2.59-5.01], lower LOA - 4.33 g/kg [95% CI = - 5.54-(- 3.12)]. CONCLUSIONS: This exponential function might be a valuable tool to assess lung edema in experiments involving 16-50 kg female domestic piglets. The error that can be made due to the 95% confidence intervals of the formula is smaller than the one made considering the lung to body weight as a linear relationship.

Determinants of acute kidney injury during high-power mechanical ventilation: secondary analysis from experimental data.

BACKGROUND: The individual components of mechanical ventilation may have distinct effects on kidney perfusion and on the risk of developing acute kidney injury; we aimed to explore ventilatory predictors of acute kidney failure and the hemodynamic changes consequent to experimental high-power mechanical ventilation. METHODS: Secondary analysis of two animal studies focused on the outcomes of different mechanical power settings, including 78 pigs mechanically ventilated with high mechanical power for 48 h. The animals were categorized in four groups in accordance with the RIFLE criteria for acute kidney injury (AKI), using the end-experimental creatinine: (1) NO AKI: no increase in creatinine; (2) RIFLE 1-Risk: increase of creatinine of > 50%; (3) RIFLE 2-Injury: two-fold increase of creatinine; (4) RIFLE 3-Failure: three-fold increase of creatinine; RESULTS: The main ventilatory parameter associated with AKI was the positive end-expiratory pressure (PEEP) component of mechanical power. At 30 min from the initiation of high mechanical power ventilation, the heart rate and the pulmonary artery pressure progressively increased from group NO AKI to group RIFLE 3. At 48 h, the hemodynamic variables associated with AKI were the heart rate, cardiac output, mean perfusion pressure (the difference between mean arterial and central venous pressures) and central venous pressure. Linear regression and receiving operator characteristic analyses showed that PEEP-induced changes in mean perfusion pressure (mainly due to an increase in CVP) had the strongest association with AKI. CONCLUSIONS: In an experimental setting of ventilation with high mechanical power, higher PEEP had the strongest association with AKI. The most likely physiological determinant of AKI was an increase of pleural pressure and CVP with reduced mean perfusion pressure. These changes resulted from PEEP per se and from increase in fluid administration to compensate for hemodynamic impairment consequent to high PEEP.

Ultrasound-guided flexor sheath block as a valid alternative to blind techniques for finger pain treatment: the horseshoe sign.

BACKGROUND: The flexor sheath digital block allows effective analgesia and anesthesia for finger pain control. To date, only blind techniques are described in the literature in patients with finger fractures, supposedly due to the superficial position of the structures used as landmarks. We describe an ultrasound-guided technique with a definite endpoint to achieve this block. To our knowledge, this is the first clinical application of this procedure. METHODS: We performed a preoperative ultrasound-guided flexor sheath digital block on a young patient with a proximal phalanx fracture, undergoing an osteotomy with plate placement. After performing the block, opioid-free general anesthesia was performed. A "hockey-stick" ultrasound probe and 1.5 mL of 0.5% levobupivacaine were used to infiltrate the flexor sheath. The "horseshoe sign" was our visual endpoint for successful block performance. RESULTS: At the time of surgical incision, there was no hemodynamic response. No opioids were administered during the case or in the recovery room, and the patient's pain scores in recovery and at discharge were 0/10 on the Numerical Rating Scale. No complications were observed or reported. CONCLUSIONS: The ultrasound-guided flexor digital sheath block is a valid alternative to the blind technique, allowing direct visualization and, thereby, confirming transthecal injection of the local anesthetic. The continuously increasing availability of ultrasound machines in emergency departments and operating theaters may encourage the spread of this technique.

Fluid balance in critically ill children with lower respiratory tract viral infection: a cohort study.

BACKGROUND: Increasing evidence has associated positive fluid balance of critically ill patients with poor outcomes. The aim of this study was to explore the pattern of daily fluid balances and their association with outcomes in critically ill children with lower respiratory tract viral infection. METHODS: A retrospective single-center study was conducted, in children supported with high-flow nasal cannula, non-invasive ventilation, or invasive ventilation. Median (interquartile range) daily fluid balances, cumulative fluid overload (FO) and peak FO variation, indexed as the % of admission body weight, over the first week of Pediatric Intensive Care Unit admission, and their association with the duration of respiratory support were assessed. RESULTS: Overall, 94 patients with a median age of 6.9 (1.9-18) months, and a respiratory support duration of 4 (2-7) days, showed a median (interquartile range) daily fluid balance of 18 (4.5-19.5) ml/kg at day 1, which decreased up to day 3 to 5.9 (- 14 to 24.9) ml/kg and increased to 13 (- 11 to 29.9) ml/kg at day 7 (p = 0.001). Median cumulative FO% was 4.6 (- 0.8 to 11) and peak FO% was 5.7 (1.9-12.4). Daily fluid balances, once patients were stratified according to the respiratory support, were significantly lower in those requiring mechanical ventilation (p = 0.003). No correlation was found between all examined fluid balances and respiratory support duration or oxygen saturation, even after subgroup analysis of patients with invasive mechanical ventilation, or respiratory comorbidities, or bacterial coinfection, or of patients under 1 year old. CONCLUSIONS: In a cohort of children with bronchiolitis, fluid balance was not associated with duration of respiratory support or other parameters of pulmonary function.