Focus on focus: Lack of coherence between systemic and microvascular indices of oedema formation

Background: Fluid therapy remains a cornerstone of therapy in shock states. However, fluid overloading ultimately results in oedema formation which is related to excess morbidity and mortality. Handheld microscopes are now frequently used to study the sublingual microcirculation. As a corollary, these devices measure focal distance, or surface to capillary distance. Physiologically, this could represent a microvascular index of oedema formation and could have the potential to guide fluid therapy. This potential tool should be investigated, especially given the frequently reported lack of coherence between systemic and microvascular parameters in the critically ill. Therefore, we set out to assess the correlation between microvascular focal distance and systemic indices of oedema formation, specifically fluid balance and weight gain. Methods: Following ex vivo testing of focal distance measurement reliability, we conducted a prospective observational cohort study in patients admitted to the intensive care unit of our university teaching hospital. We determined surface to capillary distance using sidestream dark field (SDF) and incident dark field (IDF) imaging by assessing the focal distance point or object distance range at which a sharp recording could be made. Measurements were performed in post-cardiac surgery patients and in patients following emergency admission at two time points separated by at least several hours. Data on fluid balance, weight and weight gain were collected simultaneously. Results: Sixty patients were included. The focal setting, focus point for SDF and the object distance range for IDF did not differ significantly between time points. Focus was not correlated with difference in fluid balance or weight gain. Conclusions: There is a lack of coherence between surface to capillary distance as determined by SDF or IDF imaging and fluid balance or weight gain. Thus, focal distance as a microvascular index of oedema formation cannot currently be used as a proxy for systemic indices of oedema formation. However, given the lack of coherence, further research should determine whether focal distance may provide better guidance for fluid therapy than traditional markers of overzealous fluid administration

Association between early cumulative fluid balance and successful liberation from invasive ventilation in COVID-19 ARDS patients - insights from the PRoVENT-COVID study:a national, multicenter, observational cohort analysis

BACKGROUND: Increasing evidence indicates the potential benefits of restricted fluid management in critically ill patients. Evidence lacks on the optimal fluid management strategy for invasively ventilated COVID-19 patients. We hypothesized that the cumulative fluid balance would affect the successful liberation of invasive ventilation in COVID-19 patients with acute respiratory distress syndrome (ARDS). METHODS: We analyzed data from the multicenter observational 'PRactice of VENTilation in COVID-19 patients' study. Patients with confirmed COVID-19 and ARDS who required invasive ventilation during the first 3 months of the international outbreak (March 1, 2020, to June 2020) across 22 hospitals in the Netherlands were included. The primary outcome was successful liberation of invasive ventilation, modeled as a function of day 3 cumulative fluid balance using Cox proportional hazards models, using the crude and the adjusted association. Sensitivity analyses without missing data and modeling ARDS severity were performed. RESULTS: Among 650 patients, three groups were identified. Patients in the higher, intermediate, and lower groups had a median cumulative fluid balance of 1.98 L (1.27-7.72 L), 0.78 L (0.26-1.27 L), and - 0.35 L (- 6.52-0.26 L), respectively. Higher day 3 cumulative fluid balance was significantly associated with a lower probability of successful ventilation liberation (adjusted hazard ratio 0.86, 95% CI 0.77-0.95, P = 0.0047). Sensitivity analyses showed similar results. CONCLUSIONS: In a cohort of invasively ventilated patients with COVID-19 and ARDS, a higher cumulative fluid balance was associated with a longer ventilation duration, indicating that restricted fluid management in these patients may be beneficial. Trial registration Clinicaltrials.gov ( NCT04346342 ); Date of registration: April 15, 2020

Immunobiological effects of tocilizumab across respiratory subphenotypes in COVID-19 ARDS

Background: Two distinct longitudinal respiratory subphenotypes have recently been described in COVID-19-related acute respiratory distress syndrome (ARDS). These subphenotypes exhibit dynamic immunobiological changes that may help guide immunomodulatory interventions. However, the extent to which the immune response is determined by respiratory subphenotype in the presence of concurrent immunomodulatory treatment remains unclear. We investigated the independent and combined effects of respiratory subphenotype and tocilizumab on inflammatory response and clinical outcomes. Methods: We analyzed patients from existing COVID-19 biobanks who were consecutively admitted to the ICU and received more than 4 days of invasive mechanical ventilation between March 2020 and May 2022. Patients were classified into two previously described longitudinal respiratory subphenotypes—characterized by mechanical power, minute volume and ventilatory ratio—referred to as ‘low-power’ and ‘high-power’ subphenotypes. We analyzed how tocilizumab treatment and respiratory subphenotype were associated with endothelial and inflammatory plasma biomarkers on days 0, 4 and 7, as well as with mortality. Results: 720 patients were included, of whom 464 (64%) and 256 (36%) were assigned to the low- and high-power subphenotypes, respectively. 108 (23%) of the low-power subphenotype patients received tocilizumab, and 43 (17%) of the high-power subphenotype. 427 patients had plasma samples available. The high-power subphenotype was associated with slightly higher SP-D, thrombomodulin and TNF-RI plasma concentrations on the day of intubation compared to the low-power subphenotype, along with a more rapid increase in IL-6 and TNF-RI levels in subjects who had received tocilizumab treatment (β = 0.14 log ng/ml, p = 0.022, and β = 0.06 log ng/ml, p = 0.014, respectively). Tocilizumab treatment accounted for four times more variance in IL-6 and angiopoietin-2 levels than subphenotype, while subphenotype explained only a small proportion of the variance and slightly more than tocilizumab for TNF-RI and thrombomodulin. Subphenotype did not modify the association between tocilizumab and mortality (IPTW adjusted hazard ratio 1.18; 95%CI 0.60–2.33). Conclusion:Respiratory subphenotypes showed varying TNF-RI and IL-6 responses to tocilizumab, but these differences were only minor compared to the drug’s overall immunobiological effect. This suggests that respiratory subphenotype should not determine tocilizumab treatment decisions.</p

C-Terminal Proarginine Vasopressin is Associated with Disease Outcome and Mortality, but not with Delayed Cerebral Ischemia in Critically Ill Patients with an Aneurysmal Subarachnoid Hemorrhage: A Prospective Cohort Study

Background: Aneurysmal subarachnoid hemorrhage (aSAH) is an important indication for intensive care unit admission and may lead to significant morbidity and mortality. We assessed the ability of C-terminal proarginine vasopressin (CT-proAVP) to predict disease outcome, mortality, and delayed cerebral ischemia (DCI) in critically ill patients with aSAH compared with the World Federation of Neurological Surgeons (WFNS) score and Acute Physiological and Chronic Health Evaluation IV (APACHE IV) model. Methods: C-terminal proarginine vasopressin was collected on admission in this single-center, prospective, observational cohort study. The primary aim was to investigate the relationship between CT-proAVP and poor functional outcome at 1 year (Glasgow Outcome Scale score 1–3) in a multivariable logistic regression model adjusted for WFNS and APACHE IV scores. Secondary aims were mortality and DCI. The multivariable logistic regression model for DCI was also adjusted for the modified Fisher scale. Results: In 100 patients, the median CT-proAVP level was 24.9 pmol/L (interquartile range 11.5–53.8); 45 patients had a poor 1-year functional outcome, 19 patients died within 30 days, 25 patients died within 1 year, and DCI occurred in 28 patients. Receiver operating characteristics curves revealed high accuracy for CT-proAVP to identify patients with poor 1-year functional outcome (area under the curve [AUC] 0.84, 95% confidence interval [CI] 0.77–0.92, p < 0.001), 30-day mortality (AUC 0.84, 95% CI 0.76–0.93, p < 0.001), and 1-year mortality (AUC 0.79, 95% CI 0.69–0.89, p < 0.001). CT-proAVP had a low AUC for identifying patients with DCI (AUC 0.67, 95% CI 0.55–0.79, p 0.008). CT-proAVP ≥ 24.9 pmo/L proved to be a significant predictor for poor 1-year functional outcome (odds ratio [OR] 8.04, 95% CI 2.97–21.75, p < 0.001), and CT-proAVP ≥ 29.1 pmol/L and ≥ 27.7 pmol/L were significant predictors for 30-day and 1-year mortality (OR 9.31, 95% CI 1.55–56.07, p 0.015 and OR 5.15, 95% CI 1.48–17.93, p 0.010) in multivariable models with WFNS and APACHE IV scores. CT-proAVP ≥ 29.5 pmol/L was not a significant predictor for DCI in a multivariable model adjusted for the modified Fisher scale (p = 0.061). Conclusions: C-terminal proarginine vasopressin was able to predict poor functional outcome and mortality in critically ill patients with aSAH. Its prognostic ability to predict DCI was low. Trial Registration: Nederlands Trial Register: NTR4118

Personalized mechanical ventilation guided by ultrasound in patients with acute respiratory distress syndrome (PEGASUS): study protocol for an international randomized clinical trial

: Background : Acute respiratory distress syndrome (ARDS) is a frequent cause of hypoxemic respiratory failure with a mortality rate of approximately 30%. Identifying ARDS subphenotypes based on “focal” or “non-focal” lung morphology has the potential to better target mechanical ventilation strategies of individual patients. However, classifying morphology through chest radiography or computed tomography is either inaccurate or impractical. Lung ultrasound (LUS) is a non-invasive bedside tool that can accurately distinguish “focal” from “non-focal” lung morphology. We hypothesize that LUS-guided personalized mechanical ventilation in ARDS patients leads to a reduction in 90-day mortality compared to conventional mechanical ventilation. Methods: The Personalized Mechanical Ventilation Guided by UltraSound in Patients with Acute Respiratory Distress Syndrome (PEGASUS) study is an investigator-initiated, international, randomized clinical trial (RCT) that plans to enroll 538 invasively ventilated adult intensive care unit (ICU) patients with moderate to severe ARDS. Eligible patients will receive a LUS exam to classify lung morphology as “focal” or “non-focal”. Thereafter, patients will be randomized within 12 h after ARDS diagnosis to receive standard care or personalized ventilation where the ventilation strategy is adjusted to the morphology subphenotype, i.e., higher positive end-expiratory pressure (PEEP) and recruitment maneuvers for “non-focal” ARDS and lower PEEP and prone positioning for “focal” ARDS. The primary endpoint is all-cause mortality at day 90. Secondary outcomes are mortality at day 28, ventilator-free days at day 28, ICU length of stay, ICU mortality, hospital length of stay, hospital mortality, and number of complications (ventilator-associated pneumonia, pneumothorax, and need for rescue therapy). After a pilot phase of 80 patients, the correct interpretation of LUS images and correct application of the intervention within the safe limits of mechanical ventilation will be evaluated. Discussion: PEGASUS is the first RCT that compares LUS-guided personalized mechanical ventilation with conventional ventilation in invasively ventilated patients with moderate and severe ARDS. If this study demonstrates that personalized ventilation guided by LUS can improve the outcomes of ARDS patients, it has the potential to shift the existing one-size-fits-all ventilation strategy towards a more individualized approach. Trial registration: The PEGASUS trial was registered before the inclusion of the first patient, https://clinicaltrials.gov/ (ID: NCT05492344)

Plasma transfusion in the intensive care unit

Background: Current guidelines discourage prophylactic plasma use in non‐bleeding patients. This study assesses global plasma transfusion practices in the intensive care unit (ICU) and their alignment with current guidelines. Study Design and Methods: This was a sub‐study of an international, prospective, observational cohort. Primary outcomes were in‐ICU occurrence rate of plasma transfusion, proportion of plasma events of total blood products events, and number of plasma units per event. Secondary outcomes included transfusion indications, INR/PT, and proportion of events for non‐bleeding indications. Results: Of 3643 patients included, 356 patients (10%) experienced 547 plasma transfusion events, accounting for 18% of total transfusion events. A median of 2 (IQR 1, 2) units was given per event excluding massive transfusion protocol (MTP) and 3 (IQR 2, 6) when MTP was activated. MTP accounted for 39 (7%) of events. Indications of non‐MTP events included active bleeding (54%), prophylactic (25%), and pre‐procedure (12%). Target INR/PT was stated for 43% of transfusion events; pre‐transfusion INR/PT or visco‐elastic hemostatic assays (VHA) were reported for 73%. Thirty‐seven percent of events were administered for non‐bleeding indications, 54% with a pre‐transfusion INR < 3.0 and 30% with an INR < 1.5. Discussion: Plasma transfusions occurred in 10% of ICU patients. Over a third were given for non‐bleeding indications and might have been avoidable. Target INR/PT was not stated in more than half of transfusions, and pre‐transfusion INR/PT or VHA was not reported for 27%. Further research and education is needed to optimize guideline implementation and to identify appropriate indications for plasma transfusion

Personalized mechanical ventilation guided by ultrasound in patients with acute respiratory distress syndrome (PEGASUS): study protocol for an international randomized clinical trial

background acute respiratory distress syndrome (ARDS) is a frequent cause of hypoxemic respiratory failure with a mortality rate of approximately 30%. Identifying ARDS subphenotypes based on "focal" or "non-focal" lung morphology has the potential to better target mechanical ventilation strategies of individual patients. however, classifying morphology through chest radiography or computed tomography is either inaccurate or impractical. Lung ultrasound (LUS) is a non-invasive bedside tool that can accurately distinguish "focal" from "non-focal" lung morphology. We hypothesize that LUS-guided personalized mechanical ventilation in ARDS patients leads to a reduction in 90-day mortality compared to conventional mechanical ventilation. methods the personalized mechanical ventilation guided by ultrasound in patients with acute respiratory distress syndrome (PEGASUS) study is an investigator-initiated, international, randomized clinical trial (RCT) that plans to enroll 538 invasively ventilated adult intensive care unit (ICU) patients with moderate to severe ARDS. eligible patients will receive a LUS exam to classify lung morphology as "focal" or "non-focal". thereafter, patients will be randomized within 12 h after ARDS diagnosis to receive standard care or personalized ventilation where the ventilation strategy is adjusted to the morphology subphenotype, i.e., higher positive end-expiratory pressure (PEEP) and recruitment maneuvers for "non-focal" ARDS and lower PEEP and prone positioning for "focal" ARDS. the primary endpoint is all-cause mortality at day 90. secondary outcomes are mortality at day 28, ventilator-free days at day 28, ICU length of stay, ICU mortality, hospital length of stay, hospital mortality, and number of complications (ventilator-associated pneumonia, pneumothorax, and need for rescue therapy). after a pilot phase of 80 patients, the correct interpretation of LUS images and correct application of the intervention within the safe limits of mechanical ventilation will be evaluated. discussion PEGASUS is the first RCT that compares LUS-guided personalized mechanical ventilation with conventional ventilation in invasively ventilated patients with moderate and severe ARDS. If this study demonstrates that personalized ventilation guided by LUS can improve the outcomes of ARDS patients, it has the potential to shift the existing one-size-fits-all ventilation strategy towards a more individualized approach. trial registration the PEGASUS trial was registered before the inclusion of the first patient, https://clinicaltrials.gov/ (ID: NCT05492344)