Anthony P. Pietropaoli

Inhalation of Ultrafine Particles Alters Blood Leukocyte Expression of Adhesion Molecules in Humans

Ultrafine particles (UFPs; aerodynamic diameter < 100 nm) may contribute to the respiratory and cardiovascular morbidity and mortality associated with particulate air pollution. We tested the hypothesis that inhalation of carbon UFPs has vascular effects in healthy and asthmatic subjects, detectable as alterations in blood leukocyte expression of adhesion molecules. Healthy subjects inhaled filtered air and freshly generated elemental carbon particles (count median diameter ~ 25 nm, geometric standard deviation ~ 1.6), for 2 hr, in three separate protocols: 10 μg/m3 at rest, 10 and 25 μg/m3 with exercise, and 50 μg/m3 with exercise. In a fourth protocol, subjects with asthma inhaled air and 10 μg/m3 UFPs with exercise. Peripheral venous blood was obtained before and at intervals after exposure, and leukocyte expression of surface markers was quantitated using multiparameter flow cytometry. In healthy subjects, particle exposure with exercise reduced expression of adhesion molecules CD54 and CD18 on monocytes and CD18 and CD49d on granulocytes. There were also concentration-related reductions in blood monocytes, basophils, and eosinophils and increased lymphocyte expression of the activation marker CD25. In subjects with asthma, exposure with exercise to 10 μg/m3 UFPs reduced expression of CD11b on monocytes and eosinophils and CD54 on granulocytes. Particle exposure also reduced the percentage of CD4+ T cells, basophils, and eosinophils. Inhalation of elemental carbon UFPs alters peripheral blood leukocyte distribution and expression of adhesion molecules, in a pattern consistent with increased retention of leukocytes in the pulmonary vascular bed.

Pulmonary Function, Diffusing Capacity, and Inflammation in Healthy and Asthmatic Subjects Exposed to Ultrafine Particles

Particulate air pollution is associated with asthma exacerbations and increased morbidity and mortality from respiratory causes. Ultrafine particles (particles less than 0.1 μ m in diameter) may contribute to these adverse effects because they have a higher predicted pulmonary deposition, greater potential to induce pulmonary inflammation, larger surface area, and enhanced oxidant capacity when compared with larger particles on a mass basis. We hypothesized that ultrafine particle exposure would induce airway inflammation in susceptible humans. This hypothesis was tested in a series of randomized, double-blind studies by exposing healthy subjects and mild asthmatic subjects to carbon ultrafine particles versus filtered air. Both exposures were delivered via a mouthpiece system during rest and moderate exercise. Healthy subjects were exposed to particle concentrations of 10, 25, and 50 μ g/m3, while asthmatics were exposed to 10 μ g/m3. Lung function and airway inflammation were assessed by symptom scores, pulmonary function tests, and airway nitric oxide parameters. Airway inflammatory cells were measured via induced sputum analysis in several of the protocols. There were no differences in any of these measurements in normal or asthmatic subjects when exposed to ultrafine particles at concentrations of 10 or 25 μ g/m3. However, exposing 16 normal subjects to the higher concentration of 50 μ g/m3 caused a reduction in maximal midexpiratory flow rate (−4.34 ± 1.78% [ultrafine particles] vs. +1.08 ± 1.86% [air], p =. 042) and carbon monoxide diffusing capacity (−1.76 ± 0.66 ml/min/mm Hg [ultrafine particles] vs. −0.18 ± 0.41 ml/min/mm Hg [air], p =. 040) at 21 h after exposure. There were no consistent differences in symptoms, induced sputum, or exhaled nitric oxide parameters in any of these studies. These results suggest that exposure to carbon ultrafine particles results in mild small-airways dysfunction together with impaired alveolar gas exchange in normal subjects. These effects do not appear related to airway inflammation. Additional studies are required to confirm these findings in normal subjects, compare them with additional susceptible patient populations, and determine their pathophysiologic mechanisms.

Structure, process, and annual ICU mortality across 69 centers: United States critical illness and injury trials group critical illness outcomes study

Objective:Hospital-level variations in structure and process may affect clinical outcomes in ICUs. We sought to characterize the organizational structure, processes of care, use of protocols, and standardized outcomes in a large sample of U.S. ICUs. Design:We surveyed 69 ICUs about organization, size, volume, staffing, processes of care, use of protocols, and annual ICU mortality. Setting:ICUs participating in the United States Critical Illness and Injury Trials Group Critical Illness Outcomes Study. Subjects:Sixty-nine intensivists completed the survey. Measurements and Main Results:We characterized structure and process variables across ICUs, investigated relationships between these variables and annual ICU mortality, and adjusted for illness severity using Acute Physiology and Chronic Health Evaluation II. Ninety-four ICU directors were invited to participate in the study and 69 ICUs (73%) were enrolled, of which 25 (36%) were medical, 24 (35%) were surgical, and 20 (29%) were of mixed type, and 64 (93%) were located in teaching hospitals with a median number of five trainees per ICU. Average annual ICU mortality was 10.8%, average Acute Physiology and Chronic Health Evaluation II score was 19.3, 58% were closed units, and 41% had a 24-hour in-house intensivist. In multivariable linear regression adjusted for Acute Physiology and Chronic Health Evaluation II and multiple ICU structure and process factors, annual ICU mortality was lower in surgical ICUs than in medical ICUs (5.6% lower [95% CI, 2.4–8.8%]) or mixed ICUs (4.5% lower [95% CI, 0.4–8.7%]). We also found a lower annual ICU mortality among ICUs that had a daily plan of care review (5.8% lower [95% CI, 1.6–10.0%]) and a lower bed-to-nurse ratio (1.8% lower when the ratio decreased from 2:1 to 1.5:1 [95% CI, 0.25–3.4%]). In contrast, 24-hour intensivist coverage (p = 0.89) and closed ICU status (p = 0.16) were not associated with a lower annual ICU mortality. Conclusions:In a sample of 69 ICUs, a daily plan of care review and a lower bed-to-nurse ratio were both associated with a lower annual ICU mortality. In contrast to 24-hour intensivist staffing, improvement in team communication is a low-cost, process-targeted intervention strategy that may improve clinical outcomes in ICU patients.

Effect of Inhaled Carbon Ultrafine Particles on Reactive Hyperemia in Healthy Human Subjects

Background Ultrafine particles (UFP) may contribute to the cardiovascular effects of exposure to particulate air pollution, partly because of their relatively efficient alveolar deposition and potential to enter the pulmonary vascular space. Objectives This study tested the hypothesis that inhalation of elemental carbon UFP alters systemic vascular function. Methods Sixteen healthy subjects (mean age, 26.9 ± 6.5 years) inhaled air or 50 μg/m3 elemental carbon UFP by mouthpiece for 2 hr, while exercising intermittently. Measurements at preexposure baseline, 0 hr (immediately after exposure), 3.5 hr, 21 hr, and 45 hr included vital signs, venous occlusion plethysmography and reactive hyperemia of the forearm, and venous plasma nitrate and nitrite levels. Results Peak forearm blood flow after ischemia increased 3.5 hr after exposure to air but not UFP (change from preexposure baseline, air: 9.31 ± 3.41; UFP: 1.09 ± 2.55 mL/min/100 mL; t-test, p = 0.03). Blood pressure did not change, so minimal resistance after ischemia (mean blood pressure divided by forearm blood flow) decreased with air, but not UFP [change from preexposure baseline, air: −0.48 ± 0.21; UFP: 0.07 ± 0.19 mmHg/mL/min; analysis of variance (ANOVA), p = 0.024]. There was no UFP effect on pre-ischemia forearm blood flow or resistance, or on total forearm blood flow after ischemia. Venous nitrate levels were significantly lower after exposure to carbon UFP compared with air (ANOVA, p = 0.038). There were no differences in venous nitrite levels. Conclusions Inhalation of 50 μg/m3 carbon UFP during intermittent exercise impairs peak forearm blood flow during reactive hyperemia in healthy human subjects.

Gender differences in mortality in patients with severe sepsis or septic shock.

BACKGROUNDnAlthough the incidence of sepsis is higher in men than in women, it is controversial whether there are sex-based differences in sepsis-associated mortality.nnnOBJECTIVEnThe aim of this study was to test the hypothesis that hospital mortality is higher in males compared with females with severe sepsis/septic shock who require intensive care.nnnMETHODSnThis was a retrospective cohort study of intensive care unit (ICU) patients hospitalized (in 98 ICUs in 71 US hospitals and 4 Canadian or Brazilian hospitals) with severe sepsis/septic shock between mid-2003 and 2006, using data from the Cerner Project IMPACT database.nnnRESULTSnData were analyzed for 18,757 ICU patients (median age, 66 years; interquartile range, 53-77 years), including 8702 females (46%). Hospital mortality was higher in female patients compared with male patients (35% vs 33%, respectively; P = 0.006). After adjusting for differences in baseline characteristics and processes of care, females had a higher likelihood of hospital mortality than did males (odds ratio [OR] = 1.11; 95% CI, 1.04-1.19; P = 0.002). Female patients were less likely than male patients to receive deep venous thrombosis prophylaxis (OR = 0.90; 95% CI, 0.84-0.97), invasive mechanical ventilation (OR = 0.81; 95% CI, 0.76-0.86), or hemodialysis catheters (OR = 0.85; 95% CI, 0.78-0.93). Females were more likely than males to receive red blood cell transfusions (OR = 1.15; 95% CI, 1.09-1.22) and code status limitations (OR = 1.31; 95% CI, 1.18-1.47).nnnCONCLUSIONSnIn this large cohort of ICU patients, females with severe sepsis/septic shock had a higher risk of dying in the hospital than did males. This difference remained after multivariable adjustment. Significant gender disparities were also found in some aspects of care delivery, but these did not explain the higher mortality in female patients.

Vascular Effects of Ultrafine Particles in Persons with Type 2 Diabetes

Background Diabetes confers an increased risk for cardiovascular effects of airborne particles. Objective We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. Methods In a randomized, double-blind, crossover trial, 19 subjects with type 2 diabetes inhaled filtered air or 50 μg/m3 elemental carbon UFP (count median diameter, 32 nm) by mouthpiece for 2 hr at rest. We repeatedly measured markers of vascular activation, coagulation, and systemic inflammation before and after exposure. Results Compared with air, particle exposure increased platelet expression of CD40 ligand (CD40L) and the number of platelet-leukocyte conjugates 3.5 hr after exposure. Soluble CD40L decreased with UFP exposure. Plasma von Willebrand factor increased immediately after exposure. There were no effects of particles on plasma tissue factor, coagulation factors VII or IX, or D-dimer. Conclusions Inhalation of elemental carbon UFP for 2-hr transiently activated platelets, and possibly the vascular endothelium, in people with type 2 diabetes.

The ratio of arginine to dimethylarginines is reduced and predicts outcomes in patients with severe sepsis.

Objectives: Arginine deficiency may contribute to microvascular dysfunction, but previous studies suggest that arginine supplementation may be harmful in sepsis. Systemic arginine availability can be estimated by measuring the ratio of arginine to its endogenous inhibitors, asymmetric and symmetric dimethylarginine. We hypothesized that the arginine-to-dimethylarginine ratio is reduced in patients with severe sepsis and associated with severity of illness and outcomes. Design: Case-control and prospective cohort study. Setting: Medical and surgical intensive care units of an academic medical center. Patients and Subjects: One hundred nine severe sepsis and 50 control subjects. Measurements and Main Results: Plasma and urine were obtained in control subjects and within 48 hrs of diagnosis in severe sepsis patients. The arginine-to-dimethylarginine ratio was higher in control subjects vs. sepsis patients (median, 95; interquartile range, 85–114; vs. median, 34; interquartile range, 24–48; p < .001) and in hospital survivors vs. nonsurvivors (median, 39; interquartile range, 26–52; vs. median, 27; interquartile range, 19–32; p = .004). The arginine-to-dimethylarginine ratio was correlated with Acute Physiology and Chronic Health Evaluation II score (Spearmans correlation coefficient [&rgr;] = − 0.40; p < .001) and organ-failure free days (&rgr; = 0.30; p = .001). A declining arginine-to-dimethylarginine ratio was independently associated with hospital mortality (odds ratio, 1.63 per quartile; 95% confidence interval, 1.00–2.65; p = .048) and risk of death over the course of 6 months (hazard ratio, 1.41 per quartile; 95% confidence interval, 1.01–1.98; p = .043). The arginine-to-dimethylarginine ratio was correlated with the urinary nitrate-to-creatinine ratio (&rgr; = 0.46; p < .001). Conclusions: The arginine-to-dimethylarginine ratio is associated with severe sepsis, severity of illness, and clinical outcomes. The arginine-to-dimethylarginine ratio may be a useful biomarker, and interventions designed to augment systemic arginine availability in severe sepsis may still be worthy of investigation.

Sepsis lethality via exacerbated tissue infiltration and TLR-induced cytokine production by neutrophils is integrin α3β1-dependent

Integrin-mediated migration of neutrophils to infected tissue sites is vital for pathogen clearance and therefore host survival. Although β2 integrins have been shown to mediate neutrophil transendothelial migration during systemic and local inflammation, relatively little information is available regarding neutrophil migration in sepsis beyond the endothelial cell layer. In this study, we report that integrin α3β1 (VLA-3; CD49c/CD29) is dramatically upregulated on neutrophils isolated from both human septic patients and in mouse models of sepsis. Compared with the α3β1 (low) granulocytes, α3β1 (high) cells from septic animals displayed hyperinflammatory phenotypes. Administration of a α3β1 blocking peptide and conditional deletion of α3 in granulocytes significantly reduced the number of extravasating neutrophils and improved survival in septic mice. In addition, expression of α3β1 on neutrophils was associated with Toll-like receptor-induced inflammatory responses and cytokine productions. Thus, our results show that α3β1 is a novel marker of tissue homing and hyperresponsive neutrophil subtypes in sepsis, and blocking of α3β1 may represent a new therapeutic approach in sepsis treatment.

Longer RBC storage duration is associated with increased postoperative infections in pediatric cardiac surgery.

Objectives: Infants and children undergoing open heart surgery routinely require multiple RBC transfusions. Children receiving greater numbers of RBC transfusions have increased postoperative complications and mortality. Longer RBC storage age is also associated with increased morbidity and mortality in critically ill children. Whether the association of increased transfusions and worse outcomes can be ameliorated by use of fresh RBCs in pediatric cardiac surgery for congenital heart disease is unknown. Interventions: One hundred and twenty-eight consecutively transfused children undergoing repair or palliation of congenital heart disease with cardiopulmonary bypass who were participating in a randomized trial of washed versus standard RBC transfusions were evaluated for an association of RBC storage age and clinical outcomes. To avoid confounding with dose of transfusions and timing of infection versus timing of transfusion, a subgroup analysis of patients only transfused 1–2 units on the day of surgery was performed. Measurements and Main Results: Mortality was low (4.9%) with no association between RBC storage duration and survival. The postoperative infection rate was significantly higher in children receiving the oldest blood (25–38 d) compared with those receiving the freshest RBCs (7–15 d) (34% vs 7%; p = 0.004). Subgroup analysis of subjects receiving only 1–2 RBC transfusions on the day of surgery (n = 74) also demonstrates a greater prevalence of infections in subjects receiving the oldest RBC units (0/33 [0%] with 7- to 15-day storage; 1/21 [5%] with 16- to 24-day storage; and 4/20 [20%] with 25- to 38-day storage; p = 0.01). In multivariate analysis, RBC storage age and corticosteroid administration were the only predictors of postoperative infection. Washing the oldest RBCs (> 27 d) was associated with a higher infection rate and increased morbidity compared with unwashed RBCs. Discussion: Longer RBC storage duration was associated with increased postoperative nosocomial infections. This association may be secondary in part, to the large doses of stored RBCs transfused, from single-donor units. Washing the oldest RBCs was associated with increased morbidity, possibly from increased destruction of older, more fragile erythrocytes incurred by washing procedures. Additional studies examining the effect of RBC storage age on postoperative infection rate in pediatric cardiac surgery are warranted.

Protocols and hospital mortality in critically ill patients: The United States Critical Illness and Injury Trials Group Critical Illness Outcomes Study

Objective:Clinical protocols may decrease unnecessary variation in care and improve compliance with desirable therapies. We evaluated whether highly protocolized ICUs have superior patient outcomes compared with less highly protocolized ICUs. Design:Observational study in which participating ICUs completed a general assessment and enrolled new patients 1 day each week. Patients:A total of 6,179 critically ill patients. Setting:Fifty-nine ICUs in the United States Critical Illness and Injury Trials Group Critical Illness Outcomes Study. Interventions:None. Measurements and Main Results:The primary exposure was the number of ICU protocols; the primary outcome was hospital mortality. A total of 5,809 participants were followed prospectively, and 5,454 patients in 57 ICUs had complete outcome data. The median number of protocols per ICU was 19 (interquartile range, 15–21.5). In single-variable analyses, there were no differences in ICU and hospital mortality, length of stay, use of mechanical ventilation, vasopressors, or continuous sedation among individuals in ICUs with a high versus low number of protocols. The lack of association was confirmed in adjusted multivariable analysis (p = 0.70). Protocol compliance with two ventilator management protocols was moderate and did not differ between ICUs with high versus low numbers of protocols for lung protective ventilation in acute respiratory distress syndrome (47% vs 52%; p = 0.28) and for spontaneous breathing trials (55% vs 51%; p = 0.27). Conclusions:Clinical protocols are highly prevalent in U.S. ICUs. The presence of a greater number of protocols was not associated with protocol compliance or patient mortality.