Mark E. Astiz

Practice parameters for hemodynamic support of sepsis in adult patients: 2004 update

Objective:To provide the American College of Critical Care Medicine with updated guidelines for hemodynamic support of adult patients with sepsis. Data Source:Publications relevant to hemodynamic support of septic patients were obtained from the medical literature, supplemented by the expertise and experience of members of an international task force convened from the membership of the Society of Critical Care Medicine. Study Selection:Both human studies and relevant animal studies were considered. Data Synthesis:The experts articles reviewed the literature and classified the strength of evidence of human studies according to study design and scientific value. Recommendations were drafted and graded levels based on an evidence-based rating system described in the text. The recommendations were debated, and the task force chairman modified the document until <10% of the experts disagreed with the recommendations. Conclusions:An organized approach to the hemodynamic support of sepsis was formulated. The fundamental principle is that clinicians using hemodynamic therapies should define specific goals and end points, titrate therapies to those end points, and evaluate the results of their interventions on an ongoing basis by monitoring a combination of variables of global and regional perfusion. Using this approach, specific recommendations for fluid resuscitation, vasopressor therapy, and inotropic therapy of septic in adult patients were promulgated.

Monocyte response to bacterial toxins, expression of cell surface receptors, and release of anti-inflammatory cytokines during sepsis

Exposure to endotoxin produces a state of macrophage hyporesponsiveness on subsequent stimulation. Monocytes in patients with septic shock demonstrate a similar hyporesponsiveness to endotoxin. The purpose of this study was to examine whether this state of hyporesponsiveness extends to other inflammatory stimuli and the relationship of this state to cell surface receptor expression and the release of anti-inflammatory cytokines. Twelve normal volunteers, 10 patients with severe sepsis, and 9 patients with septic shock were included in the study. Monocytes from each subject were isolated and stimulated with lipopolysaccharide (LPS), staphylococcal enterotoxin B (SEB), and phorbol myristate acetate (PMA). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were measured in the supernatants by enzyme-linked immunosorbent assay (ELISA). Serum levels of transforming growth factor-beta1 (TGF-beta1), prostaglandin E2 (PGE2), and interleukin-10 (IL-10) were also measured by ELISA. The expression of monocyte CD14 and HLA-DR in whole blood were measured by flow cytometry. Patients with septic shock demonstrated significantly decreased TNF-alpha and IL-1beta release as compared with normal subjects in response to LPS. In response to SEB, patients with sepsis and patient with septic shock demonstrated significantly decreased release of TNF-alpha and IL-1beta. Significant decreases in TNF-alpha release were found in the patients with septic shock after PMA stimulation. There were no significant differences in the monocyte response to the different stimuli between patients with gram-positive sepsis and gram-negative sepsis. HLA-DR expression was significantly decreased in patients with septic shock (58 +/- 9 fluorescence units (flU)) as compared with normal subjects (102 +/- 14 flU) (p < 0.05). No differences in CD14 expression were observed. IL-10 levels were significantly increased in patients with sepsis (16 +/- 4 pg/ml) and in patients with septic shock (42 +/- 15 pg/ml) and were detectable in 1 normal subject. TGF-beta1 levels were decreased in patients with septic shock (25 +/- 6 pg/ml) as compared with those in normal subjects (37 +/- 2 pg/ml)(p < 0.05). PGE2 levels were significantly increased in patients with septic shock and patients with sepsis. These data are consistent with a more generalized monocyte hyporesponsiveness to bacterial toxins that may be related to altered cell surface receptor expression and the release of anti-inflammatory cytokines.

Impaired mitochondrial function induced by serum from septic shock patients is attenuated by inhibition of nitric oxide synthase and poly(ADP-ribose) synthase.

ObjectiveThe purpose of this study was to determine the role of nitric oxide and poly(ADP-ribose) synthase on impaired mitochondrial function in septic shock. DesignHuman umbilical vein endothelial cells were incubated with serum from ten healthy controls, 20 patients with septic shock, and seven critically ill patients who were not septic. The experiment was repeated after pretreatment with 3-aminobenzamide, a poly(ADP-ribose) synthase inhibitor, or NG-methyl-l-arginine, a nonspecific nitric oxide synthase inhibitor. MeasurementsMitochondrial respiration was measured using a modified MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay. SettingResearch laboratory. Main ResultEndothelial cell mitochondrial respiration was significantly depressed by septic serum and averaged 61% ± 6% of control values (p < .05). Incubation with septic serum as compared with control serum also significantly decreased cellular adenosine triphosphate levels (6.7 ± 1.2 nM vs. 13.5 ± 1.9 nM, p < .01). The level of mitochondrial respiration in endothelial cells exposed to septic serum did not correlate with arterial lactate concentration but was correlated with both cardiac output (rs = .52, p < .05) and mixed venous oxygen saturation (rs = .61, p < .05). Pretreatment with NG-methyl-l-arginine significantly increased mitochondrial respiration in endothelial cells treated with septic serum from 63% ± 6% of normal to 88% ± 6% (p < .05) of normal values. Similarly, pretreatment with 3-aminobenzamide increased mitochondrial respiration in endothelial cells treated with septic serum from 64% ± 6% to 100% ± 4% (p < .01) of normal values. Endothelial cells incubated with serum from nonseptic critically ill patients did not demonstrate a significant decrease in mitochondrial respiration. ConclusionIn vitro mitochondrial respiration was significantly depressed by septic serum. The addition of NG-methyl-l-arginine, a nitric oxide synthase inhibitor, and 3-aminobenzamide, a blocker of the poly(ADP-ribose) synthase pathway, significantly attenuated this suppression. These data suggest that nitric oxide and poly(ADP-ribose) synthase activation may play an important role in the inhibition of mitochondrial respiration in septic shock.

Improved Clinical Outcomes Combining House Staff Self-Assessment with an Audit-Based Quality Improvement Program

ABSTRACTBACKGROUNDThere is a focus on integrating quality improvement with medical education and advancement of the American College of Graduate Medical Education (ACGME) core competencies.OBJECTIVETo determine if audits of patients with unexpected admission to the medical intensive care unit using a self-assessment tool and a focused Morbidity and Mortality (M&M) conference improves patient care.DESIGNCharts from patients transferred from the general medical floor (GMF) to the medical intensive care unit (ICU) were reviewed by a multidisciplinary team. Physician and nursing self-assessment tools and a targeted monthly M&M conference were part of the educational component.PARTICIPANTSPhysicians and nurses participated in root cause analysis.MEASURESRecords of all patients transferred from a general medical floor (GMF) to the ICU were audited. One hundred ninety-four cases were reviewed over a 10-month period.RESULTSNew policies regarding vital signs and house staff escalation of care were initiated. The percentage of calls for patients who met medical emergency response team/critical care consult criteria increased from 53% to 73%, nurse notification of a change in a patient’s condition increased from 65% to 100%, nursing documentation of the change in the patients condition and follow-up actions increased from 65% percent to a high of 90%, the number of cardiac arrests on a GMF decreased from 3.1/1,000 discharges to 0.6/1,000 discharges (pu2009=u20090.002), and deaths on the Medicine Service decreased from 34/1,000 discharges to 24/1,000 discharges (pu2009=u20090.024).CONCLUSIONWe describe an audit-based program that involves nurses, house staff, a self-assessment tool and a focused M&M conference. The program resulted in significant policy changes, more rapid assessment of unstable patients and improved hospital outcomes.

Monophosphoryl lipid A protects against gram-positive sepsis and tumor necrosis factor.

Monophosphoryl lipid A (MPL) is a less toxic derivative of lipid A that enhances survival from endotoxemia. This study examined whether MPL induced resistance to Gram-positive sepsis and cytokines. Mice were administered MPL or saline (phosphate-buffered saline) and challenged 24 h later with live Staphylococcus aureus (SA), staphylococcus enterotoxin B (SEB), toxic shock syndrome toxin (TSST-1), and tumor necrosis factor (TNF). Survival was determined at 72 h. A separate set of animals was phlebotomized for determination of cytokines. MPL increased survival from S. aureus bacteremia from 20 to 87% (p < .05). Interleukin-6 (IL-6) and interleukin-1 (IL-1) and TNF were also significantly decreased. SEB and TSST survival were enhanced from 10 to 90% (p < .05). In SEB-treated animals, TNF and IL-6 levels were significantly decreased. Survival from TNF infusion was increased from 20 to 100% with MPL, however, no significant differences in cytokines were observed. These data suggest that MPL induces resistance to Gram-positive sepsis and cytokine-mediated activity.

Effect of recombinant activated protein C and low-dose heparin on neutrophil-endothelial cell interactions in septic shock

Objective:To examine the effects of recombinant activated protein C (rhAPC) and low-dose heparin on neutrophil-platelet-endothelial cell interactions in septic shock. Design:Controlled experiments using phase contrast microscopy to study neutrophil, platelet, and endothelial cell interactions in flowing cell suspensions under simulated physiologic conditions. Setting:University research laboratory. Patients:Adult patients with septic shock and normal volunteers. Interventions:Neutrophils and platelets removed from control subjects were stimulated with plasma and serum from 21 patients in septic shock and perfused over endothelial cells. Activated protein C, low-dose heparin, and low-dose heparin with rhAPC were added to cells suspended in septic plasma. Neutrophil rolling velocity and the number of neutrophils adherent to endothelial cells and in aggregates were determined. Flow cytometric analysis of CD11b/CD63 cells was used to identify platelet-neutrophil aggregates. Measurements and Main Results:Activated protein C significantly decreased neutrophil adhesion and aggregation and increased rolling velocity in cells stimulated with both septic serum and septic plasma. Significant decreases in platelet-neutrophil aggregates induced by septic plasma were also observed. Low-dose heparin alone had no effects on these variables. The addition of low-dose heparin to cells suspended in septic plasma and rhAPC attenuated the benefits observed with rhAPC alone in each of these variables. Conclusions:These data suggest that the in vitro addition of rhAPC decreases sepsis-induced interactions between isolated platelets, neutrophils, and endothelial cells. Low-dose heparin attenuates the benefits observed with rhAPC. The changes in neutrophil-endothelial cell interactions demonstrated with rhAPC may play a role in preserving microvascular patency in patients with septic shock.

Monophosphoryl lipid A stimulated up-regulation of nitric oxide synthase and nitric oxide release by human monocytes in vitro

Monophosphoryl lipid A (MPL) is a derivative of lipopolysaccharide (LPS) with reduced toxicity which has been shown to modulate various immune functions in monocytes. We examined whether human monocytes can be stimulated to produce nitric oxide (NO) and its catalytic enzyme nitric oxide synthase (NOS). Monocytes were stimulated with LPS or MPL and both NOS and NO (as nitrite) production were measured. MPL at high doses (> 100 micrograms/ml) stimulated monocytes to release NO that was significantly greater than both the control and LPS-treated monocytes (p < 0.05). NO release by control cells and the LPS treated cells was not significantly different. Both arginase and N-monomethyl arginine (NMLA) inhibited the MPL stimulated release of NO (p < 0.01). MPL significantly increased inducible NOS (iNOS) expression as measured by both fluorescent microscopy and flow cytometry (p < 0.05). Similarly, both soluble NOS (sNOS) and particulate NOS (pNOS) activity were significantly up-regulated by MPL (p < 0.05). Significant correlations were found between pNOS expression and sNOS release (r = 0.72, p < 0.0001) and between 12 h NO release and sNOS production (r = 0.44, p < 0.005). These experiments confirm that human monocytes can be stimulated with MPL to produce NO in vitro and suggest that up-regulation of pNOS does not preclude NO release.

MONOPHOSPHORYL LIPID A PROTECTS AGAINST GRAM-POSITIVE SEPSIS

Monophosphoryl lipid A (MPL) is a less toxic derivative of lipid A that enhances survival from endotoxemia. This study examined whether MPL induced resistance to Gram-positive sepsis and cyto-kines. Mice were administered MPL or saline (phosphate-buffered saline) and challenged 24 h later with live Staphylococcus aureus (SA), staphylococcus enterotoxin B (SEB), toxic shock syndrome toxin (TSST-1), and tumor necrosis factor (TNF). Survival was determined at 72 h. A separate set of animals was phlebotomized for determination of cytokines. MPL increased survival from S. aureus bacteremia from 20 to 87% (ρ < .05). Interleukin-6 (IL-6) and interleukin-1 (IL-1) and TNF were also significantly decreased. SEB and TSST survival were enhanced from 10 to 90% (ρ < .05). In SEB-treated animals, TNF and IL-6 levels were significantly decreased. Survival from TNF infusion was increased from 20 to 100% with MPL, however, no significant differences in cytokines were observed. These data suggest that MPL induces resistance to Gram-positive sepsis and cytokine-mediated activity.