Meade, Laurie

Background: Transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO) are leading causes of transfusion-related morbidity and mortality. Soluble factors in erythrocyte supernatant may increase risk for these complications. The authors hypothesized that point-of-care allogeneic erythrocyte washing may be an effective intervention to mitigate elevations in soluble factors as well as physiologic responses associated with transfusion-associated respiratory complications in the setting of cardiac surgery. Methods: This is a two-center, nonblinded, randomized clinical trial evaluating point-of-care washed versus standard issue allogeneic erythrocyte transfusions administered during or on the day of cardiac surgery. The primary analysis was performed via modified intention to treat. The primary outcomes assessed were changes in intermediate markers of lung injury as well as cardiopulmonary physiologic responses to erythrocyte transfusion. Secondary outcomes included the duration of intensive care unit and hospital stay, durations of mechanical ventilation and oxygen supplementation, presence of TRALI or TACO, and mortality. Results: Among 154 analyzed patients (81 washed, 73 standard issue), the median age was 66 yr, and 77 (50.0%) were women. The median (interquartile range) number of allogeneic erythrocyte units transfused on the day of surgery was 3.0 (2.0 to 5.0) in the washed erythrocyte group and 3.0 (2.0 to 4.0) in the standard issue group (P = 0.13). No between-group differences were identified in any of the assessed recipient lung injury biomarkers (all P values > adjusted alpha). Durations of intensive care unit stay (median [interquartile range], 3.0 [2.0 to 5.0] vs. 3.0 [2.0 to 4.0] days; P = 0.117) and hospital length of stay (12.0 [9.0 to 17.0] vs. 12.0 [9.0 to 17.0] days; P = 0.801) were similar, as were the number of ventilator-free days at day 28 (27.0 [27.0 to 27.0] vs. 27.0 [26.0 to 27.0]; P = 0.699) and oxygen-free days at day 28 (24.0 [19.0 to 26.0] vs. 24.0 [22.0 to 26.0]; P = 0.400). No significant differences were noted in mortality rate or in incidence rates for TRALI, TACO, and acute kidney injury. Conclusions: Among patients undergoing cardiovascular surgery with high risk of erythrocyte transfusion, point-of-care washing of allogeneic erythrocyte transfusions did not mitigate changes in intermediate markers of lung injury or cardiopulmonary physiologic responses to erythrocyte transfusion and was not associated with improved clinical outcomes.

IMPORTANCE: Meropenem dosing is typically guided by creatinine-based estimated glomerular filtration rate (eGFR), but creatinine is a suboptimal GFR marker in the critically ill. OBJECTIVES: This study aimed to develop and qualify a population pharmacokinetic model for meropenem in critically ill adults and to determine which eGFR equation based on creatinine, cystatin C, or both biomarkers best improves model performance. DESIGN, SETTING, AND PARTICIPANTS: This single-center study evaluated adults hospitalized in an ICU who received IV meropenem from 2018 to 2022. Patients were excluded if they had acute kidney injury, were on kidney replacement therapy, or were treated with extracorporeal membrane oxygenation. Two cohorts were used for population pharmacokinetic modeling: a richly sampled development cohort (n = 19) and an opportunistically sampled qualification cohort (n = 32). MAIN OUTCOMES AND MEASURES: A nonlinear mixed-effects model was developed using parametric methods to estimate meropenem serum concentrations. RESULTS: The best-fit structural model in the richly sampled development cohort was a two-compartment model with first-order elimination. The final model included time-dependent weight normalized to a 70-kg adult as a covariate for volume of distribution (Vd) and time-dependent eGFR for clearance. Among the eGFR equations evaluated, eGFR based on creatinine and cystatin C expressed in mL/min best-predicted meropenem clearance. The mean (se) Vd in the final model was 18.2 (3.5) liters and clearance was 11.5 (1.3) L/hr. Using the development cohort as the Bayesian prior, the opportunistically sampled cohort demonstrated good accuracy and low bias. CONCLUSIONS AND RELEVANCE: Contemporary eGFR equations that use both creatinine and cystatin C improved meropenem population pharmacokinetic model performance compared with creatinine-only or cystatin C-only eGFR equations in adult critically ill patients.

IMPORTANCE: Animal models and limited human studies have suggested a plausible role for platelets in the pathogenesis and resolution of acute respiratory distress syndrome (ARDS). However, there are little data regarding the role of platelets in ARDS development. OBJECTIVES: The objective of this study was to characterize the role of platelets in a postoperative ARDS model through an analysis of two platelet-specific biologic markers: thromboxane A2 (TxA2) and soluble CD-40-ligand (sCD40L). DESIGN, SETTING, AND PARTICIPANTS: This was a nested case-control study of ARDS cases matched to non-ARDS controls. Blood samples were collected from a cohort of 500 patients undergoing thoracic, aortic vascular, or cardiac surgery that placed them at high-risk of developing postoperative ARDS. MAIN OUTCOMES AND MEASURES: TxA2 and sCD40L were analyzed at baseline (prior to surgical incision) as well as 2 hours and 6 hours after the key intraoperative events believed to be associated with increased risk of postoperative ARDS. RESULTS: Of 500 patients enrolled, 20 ARDS cases were matched 1:2 to non-ARDS controls based on age, sex, surgical procedure, and surgical lung injury prediction score. Those who developed ARDS had longer surgeries, greater fluid administration, and higher peak inspiratory pressures. There were no significant differences in levels of TxA2 or sCD40L at baseline, at 2 hours, or at 6 hours. There was also no difference in the change in biomarker concentration between baseline and 2 hours or baseline and 6 hours. CONCLUSIONS: Two novel platelet-associated biologic markers (TxA2 and sCD40L) were not elevated in patients who developed ARDS in a postoperative ARDS model. Although limited by the relatively small study size, these results do not support a clear role for platelets in the early pathogenesis of postoperative ARDS.

BACKGROUND: Patients who develop ARDS from medical or traumatic causes typically present after the inciting event has already occurred. Postoperative ARDS is unique in that the inciting insult potentially responsible for ARDS is known ahead of time, which provides an opportunity to study the early pathophysiology of ARDS. The objective of this study was to better understand the early pathophysiology of postoperative ARDS through a temporal analysis of key biomarkers of interest. METHODS: We performed a case-control study of adults undergoing elective thoracic, aortic vascular, or cardiac surgery, which placed them at increased risk of developing postoperative ARDS. Biomarkers were measured at baseline, 2 h, and 6 h after the key intraoperative event believed to be responsible for ARDS. RESULTS: Of the 467 subjects enrolled, 26 developed ARDS and were matched to non-ARDS controls 1:2 based on age, sex, surgical procedure, and surgical lung injury prediction score. Patients with ARDS were more likely to have lower preoperative albumin ( P = .029), longer surgery ( P = .007), larger amounts of intraoperative fluid ( P = .036), and higher intraoperative peak inspiratory pressures ( P = .006). Baseline plasminogen activator inhibitor-1 levels were higher in the ARDS group ( P = .03). Changes in postoperative biomarker levels from baseline were greater in the ARDS group for interleukin-8 (baseline to 6 h, P = .02) and surfactant protein-D (baseline to 2 h, P = .009). CONCLUSIONS: Our study supported the hypothesis that dysregulated coagulation, inflammation, and epithelial injury are pathophysiologic features of early postoperative ARDS. Interleukin-8, plasminogen activator-1, and surfactant protein-D may help predict development of postoperative ARDS.