A Randomized Trial of Mesenchymal Stromal Cells for Moderate to Severe Acute Respiratory Distress Syndrome from COVID-19.

Rationale: There are limited therapeutic options for patients with coronavirus disease (COVID-19)-related acute respiratory distress syndrome with inflammation-mediated lung injury. Mesenchymal stromal cells offer promise as immunomodulatory agents. Objectives: Evaluation of efficacy and safety of allogeneic mesenchymal cells in mechanically-ventilated patients with moderate or severe COVID-19-induced respiratory failure. Methods: Patients were randomized to two infusions of 2 million cells/kg or sham infusions, in addition to the standard of care. We hypothesized that cell therapy would be superior to sham control for the primary endpoint of 30-day mortality. The key secondary endpoint was ventilator-free survival within 60 days, accounting for deaths and withdrawals in a ranked analysis. Measurements and Main Results: At the third interim analysis, the data and safety monitoring board recommended that the trial halt enrollment as the prespecified mortality reduction from 40% to 23% was unlikely to be achieved (n = 222 out of planned 300). Thirty-day mortality was 37.5% (42/112) in cell recipients versus 42.7% (47/110) in control patients (relative risk [RR], 0.88; 95% confidence interval, 0.64-1.21; P = 0.43). There were no significant differences in days alive off ventilation within 60 days (median rank, 117.3 [interquartile range, 60.0-169.5] in cell patients and 102.0 [interquartile range, 54.0-162.5] in control subjects; higher is better). Resolution or improvement of acute respiratory distress syndrome at 30 days was observed in 51/104 (49.0%) cell recipients and 46/106 (43.4%) control patients (odds ratio, 1.36; 95% confidence interval, 0.57-3.21). There were no infusion-related toxicities and overall serious adverse events over 30 days were similar. Conclusions: Mesenchymal cells, while safe, did not improve 30-day survival or 60-day ventilator-free days in patients with moderate and/or severe COVID-19-related acute respiratory distress syndrome.

A 56-Year-Old Man With Progressive Subacute Hypoxemia.

CASE PRESENTATION: A 56-year-old man with a medical history of diabetes, no prior lung disease, and no tobacco exposure presented with exhaustion and a nonproductive cough 7 days after working in an old farmhouse in Vermont. His friend who worked with him exhibited similar symptoms. He was treated as an outpatient with doxycycline; however, his clinical condition deteriorated and necessitated hospitalization and subsequent intubation.

Pretreatment with stress cortisol enhances the human systemic inflammatory response to bacterial endotoxin.

OBJECTIVE: There is continuing controversy regarding the effect of glucocorticoids on a systemic inflammatory process. Based ona model of glucocorticoid action that includes both pro- and anti-inflammatory effects, we used the human experimental endotoxemia model to test the hypothesis that a transient elevation of plasma cortisol to stress-associated levels would enhance a subsequent (delayed) systemic inflammatory response to bacterial endotoxin. DESIGN: Prospective, randomized, double-blind, placebo-controlled clinical investigation. SETTING: Academic medical center. SUBJECTS: Thirty-six healthy human volunteers. INTERVENTIONS: Participants were randomized to receive a 6-hr intravenous infusion of saline (control), an intermediate dose of cortisol (Cort80; 6.3 mg/hr/70 kg), or a high dose of cortisol (Cort160; 12.6 mg/hr/70 kg) on day 1. On day 2, participants received an intravenous injection of 2 ng/kg Escherichia coli endotoxin followed by serial measurements of plasma cytokine concentrations. MEASUREMENTS AND MAIN RESULTS: Baseline participant characteristics and cortisol and cytokine concentrations were similar in all three groups. The plasma cortisol response to endotoxemia on day 2 was similar in all three groups. The interleukin-6 response to endotoxemia was significantly increased in the Cort80 Group compared with the control Group (p = .004), whereas the interleukin-10 response was significantly suppressed (p = .034). Corresponding results for the Cort160 Group were not significantly different from control Group values. CONCLUSIONS: In this study, transient elevation of in vivo cortisol concentrations to levels that are observed during major systemic stress enhanced a subsequent, delayed in vivo inflammatory response to endotoxin. This appeared to be a dose-dependent effect that was more prominent at intermediate concentrations of cortisol than at higher concentrations of cortisol.

In vivo exposure to high or low cortisol has biphasic effects on inflammatory response pathways of human monocytes.

BACKGROUND: Recent studies demonstrate that glucocorticoids (GCs) have both supportive (stimulatory) and suppressive effects on immune responses, depending upon the GC concentration. Since some GC effects on inflammation are stimulatory, we hypothesized that acute in vivo GC depletion would decrease inflammatory responses of human monocytes. METHODS: Monocytes were isolated from healthy volunteer participants before and after in vivo treatment with; 1) IV saline, 2) IV high dose hydrocortisone (8 microg x kg(-1) x min(-1)) followed by oral hydrocortisone overnight, and 3) oral RU486 (200 mg at 0400 and 1600 h) to block the intracellular GC receptor and IV etomidate (1.5 mg x kg(-1) x h(-1)) for 12 h to prevent compensatory adrenal cortisol synthesis. Plasma adrenocorticotropic hormone, plasma, and salivary cortisol were measured serially. Monocytes were tested for; 1) cytokine responses, 2) expression of CD163, CD119, and CD54, and 3) mRNA levels of GC-responsive inflammatory mediators. All measurements were made with and without in vitro stimulation of monocytes by lipopolysaccharide. RESULTS: Cortisol and adrenocorticotropic hormone measurements demonstrated effective manipulation of in vivo cortisol. In vivo hypercortisolemia and in vivo GC depletion had reciprocal effects on monocyte mRNA levels of 4 important GC-responsive molecules: 1) GC receptor, CD163, interleukin-10, and suppressor of the cytokine synthesis-3. Monocyte cytokine responses and protein expression were not affected by GC depletion. CD163 expression was increased by hypercortisolemia. CONCLUSIONS: Short-term GC depletion affects mRNA levels of GC-responsive molecules but does not affect monocyte protein expression or cytokine responses.

Intraoperative management of hyperglycemia in the cardiac surgical patient.

The stress response of cardiac surgery leads to hyperglycemia, and undergoing cardiopulmonary bypass magnifies this response greatly. Counter-regulatory hormones, the cytokine response, and the automatic nervous system are all part of the coordinated host response that can lead to hyperglycemia. Postoperative hyperglycemia is associated with worsened perioperative outcomes, and there are data demonstrating this to also be true for the intraoperative period. Many factors affect intraoperative glucose control, including cardiopulmonary pump (CPB) prime fluid composition, temperature while on CPB, and medications such as catecholamines and glucocorticoids. Intraoperative glucose control has a significant impact on postoperative outcomes. No optimal intraoperative insulin regimen has been identified, but continuous intravenous infusions appear to be superior to intermittent sliding scale dosing. In addition, the technique of hyperinsulinemic glucose clamp shows the greatest promise of achieving normoglycemia while on CPB.

Rapid cardiac ultrasound of inpatients suffering PEA arrest performed by nonexpert sonographers.

UNLABELLED: Cardiac arrest presenting as pulseless electrical activity (PEA) currently has a very low survival rate. Many of the conditions underlying PEA (cardiac tamponade, hypovolemia, and pulmonary embolus) are associated with specific cardiac ultrasound findings. The aim of this study was to evaluate a rapid cardiac ultrasound assessment performed by trained nonexpert sonographers integrated into the ACLS response system at a major medical center. METHODS: An emergency sonography system was created and deployed to each inpatient cardiac arrest occurring at Dartmouth Hitchcock Medical Center between November 1, 2003 and April 30, 2004. Thirteen internal medicine house officers received training to perform a limited subcostal cardiac ultrasound examination designed to diagnose cardiac tamponade, pulmonary embolus, severe hypovolemia, and lack of cardiac motion. Time from arrest alert to sonographic result, and correlation with over-reading by blinded echocardiography physicians were assessed. RESULTS: A complete emergency ultrasound examination was performed in five PEA arrests. The average time from arrest alert to interpretation was 7.75 min. (95% CI 2.8-18.3 min). Three of these examinations (60%, 95% CI 14.7-94.7%) were adequate for interpretation. Agreement between the nonexpert sonographer and echocardiography physician occurred in four of five (kappa=0.706) cases. CONCLUSION: Rapid cardiac sonography can be successfully integrated in the ACLS response. Nonexpert sonographers may be able to provide useful interpretive information when sufficiently trained.

Endotoxin induces rapid metalloproteinase-mediated shedding followed by up-regulation of the monocyte hemoglobin scavenger receptor CD163.

CD163, a monocyte and macrophage-specific surface glycoprotein, which is increased by interleukin-10 and glucocorticoids, is a scavenger receptor for hemoglobin/haptoglobin complexes. We report a rapid and highly reproducible rise in soluble CD163 in the plasma of human volunteers given intravenous lipopolysaccharide (LPS). We also show that LPS induces shedding of CD163 from the surface of isolated monocytes, identifying shedding from monocytes and macrophages as a likely mechanism for the endotoxemia-associated rise in plasma CD163 in vivo. Studies using the inhibitor TAPI-0 indicate that a metalloproteinase is responsible for LPS-mediated shedding of CD163. Finally, we demonstrate a marked increase in surface CD163 expression on circulating monocytes 24 h following experimental endotoxemia. These findings show that CD163 is rapidly mobilized in response to bacterial endotoxin. As hemoglobin can bind LPS and enhance its toxicity, it will be important to determine how cell surface and soluble CD163 influence inflammatory processes during sepsis.

Hydrocortisone at stress-associated concentrations helps maintain human heart rate variability during subsequent endotoxin challenge.

PURPOSE: We evaluated the differential impact of stress-associated vs high pharmacologic concentrations of hydrocortisone pretreatment on heart rate variability (HRV) during a subsequent systemic inflammatory stimulus. MATERIALS AND METHODS: Healthy volunteers were randomized to receive placebo (Control) and hydrocortisone at 1.5 µg/kg per minute (STRESS) or at 3.0 µg/kg per minute (PHARM) as a 6-hour infusion. The STRESS dose was chosen to replicate the condition of physiologic adrenal cortical output during acute systemic stress. The PHARM dose was chosen to induce a supraphysiologic concentration of cortisol. The next day, all subjects received 2 ng/kg Escherichia coli endotoxin (lipopolysaccharide). Heart rate variability was analyzed with the statistic approximate entropy (ApEn). A lower ApEn correlates with decreased HRV. RESULTS: At the 3-hour nadir, the decrease in ApEn in the STRESS group was significantly less compared to placebo (P < .03), whereas ApEn in the PHARM group was not statistically different. We also found that the maximal decrease in ApEn preceded maximal increase in heart rate in all groups. The decrease in R-R interval was maximal at 4 hours, whereas the ApEn nadir was 1 hour earlier at 3 hours. CONCLUSIONS: Pretreatment with a stress dose of hydrocortisone but not a higher pharmacologic dose maintained a significantly higher ApEn after endotoxin exposure when compared to a placebo. In addition, decreases in ApEn preceded increases in heart rate.

Decreased physiologic variability as a generalized response to human endotoxemia.

OBJECTIVE: To test the effect in normal human volunteers of transient systemic inflammation on the variability in time-series behaviors of widely divergent physiologic measures of the human inflammatory response. DESIGN: Prospective study of human volunteers who were tested on 2 consecutive days, a control day and a treatment day. Each participant served as his or her own control. SETTING: Critical care facility of a university medical center. SUBJECTS: Subjects were eight healthy human volunteers. INTERVENTIONS: Participant subjects were tested on both a baseline day with no intervention and on a treatment day when they received 4 ng/kg intravenous Escherichia coli endotoxin. MEASUREMENTS AND MAIN RESULTS: Continuous electrocardiographic recordings and serial blood sampling (performed every 5 mins) were used to create time-series of heart rate (R-R intervals), neutrophil function (phagocytosis), and plasma cortisol concentrations. For each primary measure, we recorded a significant increase in the regularity (decreased variability) of the functional measurement as assessed by the statistical entity, approximate entropy. CONCLUSIONS: Increased regularity, or decreased variability, of organ functions is a generalized response to systemic inflammation that occurs in widely divergent systems during endotoxemia.

Cortisol antiinflammatory effects are maximal at postoperative plasma concentrations.

OBJECTIVE: To determine the plasma concentration of cortisol that is needed for maximal suppression of the systemic inflammatory response to cardiac surgery with cardiopulmonary bypass. DESIGN: Prospective, randomized, double-blind clinical study of cardiac surgical patients. SETTING: Operating room and inpatient care facility of a university medical center. SUBJECTS: Sixty elective cardiac surgical patients scheduled for coronary artery bypass graft, cardiac valve replacement, or both. INTERVENTIONS: Patients were randomized to receive one of three different hydrocortisone doses, by intravenous infusion, for 6 hrs before, during, and immediately after surgery while also receiving etomidate to suppress endogenous cortisol production. MEASUREMENTS AND MAIN RESULTS: Serial determinations of plasma interleukin-6 were studied as a marker of systemic inflammation. Measurements of interleukin-10 were used as a marker of the compensatory antiinflammatory response. Plasma cortisol concentrations in an untreated control group rose from 17 microg/dL before surgery to a mean of 43 microg/dL by 4 hrs after surgery. A dose of hydrocortisone (4 microg/kg/min for 6 hrs) that maintained plasma cortisol between 40 and 50 microg/dL, starting 60-90 mins before surgery, significantly suppressed plasma interleukin-6 after surgery compared with control while significantly increasing plasma interleukin-10 during surgery. Plasma interleukin-6 after surgery was not suppressed further by increasing the dose of hydrocortisone to 8 microg/kg/min, although the mean peak plasma interleukin-10 concentration increased further compared with the group that received the 4 microg/kg/min hydrocortisone dose. CONCLUSIONS: At the doses studied, cortisol-induced suppression of plasma interleukin-6 during and after cardiac surgery appears to be a saturable phenomenon at the concentration of plasma cortisol that is normally achieved after surgery in untreated patients.

Insulin increases neutrophil count and phagocytic capacity after cardiac surgery.

UNLABELLED: We previously reported that a continuous insulin infusion improves neutrophil phagocytic function after cardiac surgery in diabetic patients. These data suggested that hyperglycemia impairs neutrophil function, and because nondiabetic patients also experience hyperglycemia during cardiac surgery, we hypothesized that a continuous insulin infusion would improve glucose control and neutrophil function in nondiabetic cardiac surgical patients. Patients were randomized to receive either no insulin (Control group) or a continuous insulin infusion (Insulin group), with glucose measurements every 10 min during cardiopulmonary bypass (CPB). Blood glucose was significantly lower in the Insulin group immediately after surgery but not during surgery. When assessed as the percentage of phagocytic cells, neutrophil function was similar in the Control and Insulin groups at baseline (55% and 57%, respectively) and after CPB (38% and 43%, respectively). However, a quantitative determination of neutrophil phagocytic activity showed that whole blood neutrophil phagocytic capacity increased significantly in both groups at 60 min after CPB when compared with their respective baseline values and that the increase in total neutrophil phagocytic capacity was significantly more in the Insulin group compared with the Control group (P = 0.036). This observation was primarily due to a larger increase in the peripheral blood neutrophil count and not to increased activation of neutrophils. IMPLICATIONS: IV insulin, as used in this study, had effects on blood glucose only after cardiac surgery, when it was associated with an increased neutrophil count and a greater total capacity of peripheral blood neutrophils to ingest foreign particles.

Regulation and localization of endogenous human tristetraprolin.

Tumor necrosis factor (TNF) has been implicated in the development and pathogenicity of infectious diseases and autoimmune disorders, such as septic shock and arthritis. The zinc-finger protein tristetraprolin (TTP) has been identified as a major regulator of TNF biosynthesis. To define its intracellular location and examine its regulation of TNF, a quantitive intracellular staining assay specific for TTP was developed. We establish for the first time that in peripheral blood leukocytes, expression of endogenous TTP is confined to the cytoplasm. Baseline expression of TTP was higher in monocytes than in lymphocytes or neutrophils. After in vitro incubation with lipopolysaccharide (LPS), leukocyte TTP levels increased rapidly, peaking after approximately 2 hours. Monocytes showed the greatest response to LPS stimulation and lymphocytes the least. TTP levels were also studied in leukocytes isolated from healthy volunteers infused with a bolus dose of LPS. TTP expression and initial upregulation in response to LPS infusion were consistent with the in vitro data. Neutrophil TTP levels responded first, reaching an initial peak within 1 hour, monocyte levels peaked next at 2 hours, followed by lymphocytes at 4 hours. This response paralleled plasma TNF levels, which peaked 2 hours after infusion and were no longer detectable after 12 hours. A second rise in intracellular TTP levels, which did not parallel plasma TNF levels, was observed in all leukocyte populations, starting 12 hours after infusion. These data establish the cytoplasmic location of TTP, supporting a major role for this protein in regulating TNF production, and suggest that TTP levels are not regulated solely by TNF.

Glucocorticoid effects on the inflammatory and clinical responses to cardiac surgery.

OBJECTIVE: To measure the effects of glucocorticoids on the systemic inflammatory response and clinical recovery after cardiac surgery. DESIGN: Randomized, prospective, double-blind, placebo-controlled clinical trial with concurrent comparison groups. SETTING: University medical center. PARTICIPANTS: Patients scheduled for elective coronary artery bypass graft surgery using normothermic cardiopulmonary bypass (CPB) and a standardized anesthetic. INTERVENTIONS: Participants randomly received either methylprednisolone, 15 mg/kg intravenously 1 hour before surgery and 0.3 mg/kg intravenously every 6 hours x 4 doses, or placebo. Comparison groups included cardiac surgical patients who received etomidate to lower endogenous cortisol during surgery and healthy volunteers who received methylprednisolone only. MEASUREMENTS AND MAIN RESULTS: Patients who received methylprednisolone had a significant reduction in circulating interleukin (IL)-6 at 60 minutes after CPB (p < 0.05) and on the morning of the 1st (p < 0.01) and 3rd (p < 0.05) postoperative days and a significant increase in circulating IL-10 at 60 minutes after CPB (p < 0.01) compared with the placebo group. Etomidate, given to lower cortisol during surgery, was associated with significantly decreased IL-6 and IL-10 responses to surgery compared with the placebo group, whereas methylprednisolone alone, given to healthy nonsurgical volunteers, had no effect on these cytokines. After adjusting for age, there were no significant differences in postoperative length of hospital stay between the methylprednisolone-treated (4.6 days) and placebo (6.1 days) groups or in the duration of mechanical ventilation (9.9 hours and 15.6 hours). No patient treated with methylprednisolone had nausea and vomiting on the 1st postoperative day compared with 33% of placebo-treated patients (p = 0.02). Glucose was significantly higher after methylprednisolone treatment at 1 hour after CPB (276 mg/dL v 210 mg/dL; p = 0.001) and at 2 hours (289 mg/dL v 213 mg/dL; p = 0.009) and 8 hours (247 mg/dL v 196 mg/dL; p = 0.02) after surgery. There were no differences in pain scores and no significant intergroup differences in lung peak expiratory flow rate or alveolar-arterial oxygen gradients after surgery. CONCLUSION: This study shows significant effects of glucocorticoids on the production of IL-6 and IL-10 in response to cardiac surgery but only minor effects on clinical recovery.

Highest core temperature during cardiopulmonary bypass and rate of mediastinitis.

Temperature control during cardiopulmonary bypass (CPB) may be related to rates of bacterial infection. We assessed the relationship between highest core temperature during CPB and rates of mediastinitis in 6955 consecutive isolated coronary artery bypass graft (CABG) procedures in northern New England. The overall rate of mediastinitis was 1.1%. The association between highest core temperature and mediastinitis was different for diabetics than for nondiabetics. A multivariate model showed that there was a significant interaction between diabetes and temperature in their association with mediastinitis (p=0.015). Diabetic patients showed higher rates of mediastinitis as highest core temperature increased, from 0.7% in the < or = 37 degrees C group to 3.3% in the > or = 38 degrees C group (p(trend) = 0.002). Adjusted rates were similar. Nondiabetic patients did not show this trend (p(trend) = 0.998). Among diabetic patients, a peak core body temperature > 37.9 degrees C during CPB is a significant risk factor for development of mediastinitis. Avoidance of higher temperatures during CPB may lower the risk of mediastinitis for diabetic patients undergoing CABG surgery.

The association between heart rate and in-hospital mortality after coronary artery bypass graft surgery.

UNLABELLED: Avoidance of tachycardia is a commonly described goal for anesthetic management during coronary artery bypass graft (CABG) surgery. However, an association between increased intraoperative heart rate and mortality has not been described. We conducted an observational study to evaluate the association between preinduction heart rate (heart rate upon arrival to the operating room) and in-hospital mortality during CABG surgery. Data were collected on 5934 CABG patients. Fifteen percent of patients had an increased preinduction heart rate > or =80 bpm. Crude mortality was significantly more frequent among patients with increased preinduction heart rate (P(trend) = 0.002). After adjustment for baseline differences among patients, preinduction heart rate > or =80 bpm remained associated with increased mortality (P(trend) < 0.001). The increased heart rate may be a cause of the observed mortality. Alternatively, faster heart rate may be either a marker of patients with irreversible myocardial damage, or a marker of patients with limited cardiac reserve at risk for further injury. Lastly, faster heart rate may be a marker for under-use of beta-adrenergic blockade. Because the use of preoperative beta-adrenergic blockade in CABG patients is associated with improved in-hospital survival, further investigation concerning the effect of intraoperative treatment of increased heart rate with beta-adrenergic blockers on mortality after CABG surgery is warranted. IMPLICATIONS: We conducted an observational study to evaluate the association between heart rate upon arrival to the operating room (preinduction heart rate) and in-hospital mortality during coronary artery bypass graft surgery. After adjustment for baseline differences among patients, preinduction heart rate > or =80 bpm was associated with an increased in-hospital mortality after coronary artery bypass graft surgery.