Exhaled nitric oxide and carbon monoxide in mechanically ventilated brain-injured patients

The inflammatory influence and biological markers of prolonged mechanical-ventilation in uninjured human lungs remains controversial. We investigated exhaled nitric oxide (NO) and carbon monoxide (CO) in mechanically-ventilated, brain-injured patients in the absence of lung injury or sepsis at two different levels of positive end-expiratory pressure (PEEP). Exhaled NO and CO were assessed in 27 patients, without lung injury or sepsis, who were ventilated with 8 ml kg(-1) tidal volumes under zero end-expiratory pressure (ZEEP group, n  =  12) or 8 cm H2O PEEP (PEEP group, n  =  15). Exhaled NO and CO was analysed on days 1, 3 and 5 of mechanical ventilation and correlated with previously reported markers of inflammation and gas exchange. Exhaled NO was higher on day 3 and 5 in both patient groups compared to day 1: (PEEP group: 5.8 (4.4-9.7) versus 11.7 (6.9-13.9) versus 10.7 (5.6-16.6) ppb (p  <  0.05); ZEEP group: 5.3 (3.8-8.8) versus 9.8 (5.3-12.4) versus 9.6 (6.2-13.5) ppb NO peak levels for days 1, 3 and 5, respectively, p  <  0.05). Exhaled CO remained stable on day 3 but significantly decreased by day 5 in the ZEEP group only (6.3 (4.3-9.0) versus 8.1 (5.8-12.1) ppm CO peak levels for day 5 versus 1, p  <  0.05). The change scores for peak exhaled CO over day 1 and 5 showed significant correlations with arterial blood pH and plasma TNF levels (r s  =  0.49, p  =  0.02 and r s  =  -0.51 p  =  0.02, respectively). Exhaled NO correlated with blood pH in the ZEEP group and with plasma levels of IL-6 in the PEEP group. We observed differential changes in exhaled NO and CO in mechanically-ventilated patients even in the absence of manifest lung injury or sepsis. These may suggest subtle pulmonary inflammation and support application of real time breath analysis for molecular monitoring in critically ill patients.

Longitudinal assessment of adrenal function in the early and prolonged phases of critical illness in septic patients: relations to cytokine levels and outcome

CONTEXT

Adrenal dysfunction remains a controversial issue in critical care. The long-stay intensive care unit (ICU) population may be at increased risk of adrenal insufficiency.

OBJECTIVE

We aimed to determine whether adrenal dysfunction develops during the course of sepsis.

DESIGN

This is a prospective observational longitudinal study.

SETTING

The study was conducted in the ICU of a secondary/tertiary care hospital.

PATIENTS

We studied 51 consecutive mechanically ventilated patients with sepsis.

INTERVENTION

We measured cortisol, ACTH, cortisol-binding globulin, cytokines, and cortisol 30 minutes after 1 μg ACTH(1-24), upon sepsis diagnosis and every 3 to 4 days, until Day 30 or until recovery or death.

MAIN OUTCOME MEASURES

We looked for changes in baseline and stimulated cortisol levels and its relationship to ACTH levels, sepsis severity or survival.

RESULTS

Baseline and stimulated cortisol levels did not vary significantly. Septic patients with shock had higher baseline (20 ± 6 vs 17 ± 5 μg/dL, P = .03) and stimulated cortisol levels (26 ± 5 vs 23 ± 6 μg/dL, P = .04), compared with those without shock. On Day 1, ACTH levels could not predict cortisol levels (R(2) = 0.06, P = .08). ACTH levels increased significantly after Day 10 and, at this time point, they related to cortisol levels (R(2) = 0.35, P < .001). Development of septic shock, or resolution from it, was not associated with changes in baseline, stimulated cortisol levels, or the cortisol increment. There was much inpatient variability in the diagnosis of adrenal dysfunction at different time points.

CONCLUSIONS

Total cortisol levels relate both to the severity and outcome of sepsis and remain fairly unchanged during the course of illness. Initially, cortisol levels are largely ACTH independent, whereas ACTH increases and correlates with cortisol levels later on. Adrenal dysfunction does not seem to be a major problem during the prolonged phase of sepsis. Although not significant, the variation in cortisol levels may be such that classification of patients varies, questioning the utility of arbitrary cut-offs to define adrenal dysfunction in septic patients.

Preclinical pulmonary capillary endothelial dysfunction is present in brain dead subjects

Pulmonary endothelium is a major metabolic organ affecting pulmonary and systemic vascular homeostasis. Brain death (BD)-induced physiologic and metabolic derangements in donors’ lungs, in the absence of overt lung pathology, may cause pulmonary dysfunction and compromise post-transplant graft function. To explore the impact of BD on pulmonary endothelium, we estimated pulmonary capillary endothelium-bound (PCEB)-angiotensin converting enzyme (ACE) activity, a direct and quantifiable index of pulmonary endothelial function, in eight brain-dead patients and ten brain-injured mechanically ventilated controls. No subject suffered from acute lung injury or any other overt lung pathology. Applying indicator-dilution type techniques, we measured single-pass transpulmonary percent metabolism (%M) and hydrolysis (v) of the synthetic, biologically inactive, and highly specific for ACE substrate ³H-benzoyl-Phe-Ala-Pro, under first order reaction conditions, and calculated lung functional capillary surface area (FCSA). Substrate %M (35 ± 6.8%) and v (0.49 ± 0.13) in BD patients were decreased as compared to controls (55.9 ± 4.9, P = 0.033 and 0.9 ± 0.15, P = 0.033, respectively), denoting decreased pulmonary endothelial enzyme activity at the capillary level; FCSA, a reflection of endothelial enzyme activity per vascular bed, was also decreased (BD patients: 1,563 ± 562 mL/min vs 4,235 ± 559 in controls; P = 0.003). We conclude that BD is associated with subtle pulmonary endothelial injury, expressed by decreased PCEB-ACE activity. The applied indicator-dilution type technique provides direct and quantifiable indices of pulmonary endothelial function at the bedside that may reveal the existence of preclinical lung pathology in potential lung donors.

Nitrosative and oxidative stresses contribute to post-ischemic liver injury following severe hemorrhagic shock: the role of hypoxemic resuscitation

PURPOSE

Hemorrhagic shock and resuscitation is frequently associated with liver ischemia-reperfusion injury. The aim of the study was to investigate whether hypoxemic resuscitation attenuates liver injury.

METHODS

Anesthetized, mechanically ventilated New Zealand white rabbits were exsanguinated to a mean arterial pressure of 30 mmHg for 60 minutes. Resuscitation under normoxemia (Normox-Res group, n = 16, PaO(2) = 95-105 mmHg) or hypoxemia (Hypox-Res group, n = 15, PaO(2) = 35-40 mmHg) followed, modifying the FiO(2). Animals not subjected to shock constituted the sham group (n = 11, PaO(2) = 95-105 mmHg). Indices of the inflammatory, oxidative and nitrosative response were measured and histopathological and immunohistochemical studies of the liver were performed.

RESULTS

Normox-Res group animals exhibited increased serum alanine aminotransferase, tumor necrosis factor--alpha, interleukin (IL) -1β and IL-6 levels compared with Hypox-Res and sham groups. Reactive oxygen species generation, malondialdehyde formation and myeloperoxidase activity were all elevated in Normox-Res rabbits compared with Hypox-Res and sham groups. Similarly, endothelial NO synthase and inducible NO synthase mRNA expression was up-regulated and nitrotyrosine immunostaining increased in animals resuscitated normoxemically, indicating a more intense nitrosative stress. Hypox-Res animals demonstrated a less prominent histopathologic injury which was similar to sham animals.

CONCLUSIONS

Hypoxemic resuscitation prevents liver reperfusion injury through attenuation of the inflammatory response and oxidative and nitrosative stresses.

Hypoxemic resuscitation from hemorrhagic shock prevents lung injury and attenuates oxidative response and IL-8 overexpression

We investigated whether hypoxemic resuscitation from hemorrhagic shock prevents lung injury and explored the mechanisms involved. We subjected rabbits to hemorrhagic shock for 60 min by exsanguination to a mean arterial pressure of 40 mm Hg. By modifying the fraction of the inspired oxygen, we performed resuscitation under normoxemia (group NormoxRes, P(a)O(2)=95-105 mm Hg) or hypoxemia (group HypoxRes, P(a)O(2)=35-40 mm Hg). Animals not subjected to shock constituted the sham group (P(a)O(2)=95-105 mm Hg). We performed bronchoalveolar lavage (BAL) fluid, lung wet-to-dry weight ratio, and morphological studies. U937 monocyte-like cells were incubated with BAL fluid from each group. Cell peroxides, malondialdehyde, proteins, and cytokines in the BAL fluid were lower in sham than in shocked animals and in HypoxRes than in NormoxRes animals. The inverse was true for ascorbic acid and reduced glutathione. Lung edema, lung neutrophil infiltration, myeloperoxidase, and interleukin (IL)-8 gene expression were reduced in lungs of HypoxRes compared with NormoxRes animals. A colocalized higher expression of IL-8 and nitrotyrosine was found in lungs of NormoxRes animals compared to HypoxRes animals. The BAL fluid of NormoxRes animals compared with HypoxRes animals exerted a greater stimulation of U937 monocyte-like cells for proinflammatory cytokine release, particularly for IL-8. In the presence of p38-MAPK and Syk inhibitors and monosodium urate crystals, IL-8 release was reduced. We conclude that hypoxemic resuscitation from hemorrhagic shock ameliorates lung injury and reduces oxygen radical generation and lung IL-8 expression.

High concentrations of reactive oxygen species in the BAL fluid are correlated with lung injury in rabbits after hemorrhagic shock and resuscitation

Increased levels of cytokines or reactive oxygen species (ROS) in the bronchoalveolar lavage (BAL) fluid are associated with acute lung injury after ischemia/reperfusion. We investigated the correlation of these markers with the degree of lung injury in a rabbit model of hemorrhagic shock. Rabbits, maintained by mechanical ventilation, were left untreated (control) or subjected to hemorrhagic shock by withdrawing blood (n = 12 for each group). Shock animals were re-infused their shed blood for resuscitation. At the end of the experiment, BAL fluid was recovered, in which parameters of oxidative stress and cytokines were measured. Macrophages and malondialdehyde levels were increased (p = 0.043 and p = 0.003, respectively), and total antioxidant capacity (TAC) was decreased in the shock animals compared with control (p = 0.009). Production of ROS was significantly enhanced in shock animals compared with controls (p < 0.001). BAL fluid levels of tumor necrosis factor-alpha, interleukin (IL)-1beta and IL-6 were higher in shock rabbits by more than twofold (p < 0.001 for each). Shock animals also showed higher histopathological scores that represent severe tissue damage than controls (p = 0.022). Numbers of macrophages and levels of ROS and TAC were correlated with the degree of lung injury (p = 0.006, p = 0.02, and p = 0.04, respectively), but not cytokines. Therefore, resuscitation from hemorrhagic shock results in acute lung injury, with enhanced pulmonary oxidative and inflammatory responses. In conclusion, ROS in the BAL fluid are good markers that predict lung injury following hemorrhagic shock and resuscitation.

Reasons of PEG failure to eliminate gastroesophageal reflux in mechanically ventilated patients

AIM: To investigate factors predicting failure of percutaneous endoscopic gastrostomy (PEG) to eliminate gastroesophageal reflux (GER).

METHODS: Twenty-nine consecutive mechanically ventilated patients were investigated. Patients were evaluated for GER by pH-metry pre-PEG and on the 7th post-PEG day. Endoscopic and histologic evidence of reflux esophagitis was also carried out. A beneficial response to PEG was considered when pH-metry on the 7th post-PEG day showed that GER was below 4%.

RESULTS: Seventeen patients responded (RESP group) and 12 did not respond (N-RESP) to PEG. The mean age, sex, weight and APACHE II score were similar in both groups. GER (%) values were similar in both groups at baseline, but were significantly reduced in the RESP group compared with the N-RESP group on the 7th post-PEG day [2.5 (0.6-3.8) vs 8.1 (7.4-9.2, P < 0.001)]. Reflux esophagitis and the gastroesophageal flap valve (GEFV) grading differed significantly between the two groups (P = 0.031 and P = 0.020, respectively). Histology revealed no significant differences between the two groups.

CONCLUSION: Endoscopic grading of GEFV and the presence of severe reflux esophagitis are predisposing factors for failure of PEG to reduce GER in mechanically ventilated patients.

Hypoxemic resuscitation after hemorrhagic shock is accompanied by reduced serum levels of angiopoietin-2

BACKGROUND

To investigate whether angiopoietin-2 (Ang2) and vascular endothelial growth factor (VEGF) are implicated in the hypoxemic resuscitation from hemorrhagic shock.

METHODS

Twenty rabbits were subjected to hemorrhagic shock after blood exsanguination; resuscitation was performed by infusion of the shed blood in ten rabbits under normoxemic conditions (NormoxRes) and in 10 under hypoxemic conditions (HypoxRes); four rabbits were subjected to sham operation. Serum was drawn at serial time intervals; serum was applied for stimulation of U937 monocytes.

RESULTS

Serum concentrations of Ang2 were higher in the NormoxRes group compared to the HypoxRes group at 90 min (p: 0.049) and at 120 min (p: 0.028). Serum concentrations of VEGF did not differ between groups. Concentrations of VEGF in the supernatants of U937 stimulated with sera of all groups were below detection limit. The wet to dry lung ratio of the HypoxRes group was significantly lower than the NormoxRes group (p<0.0001).

CONCLUSIONS

Hypoxemic resuscitation from hemorrhagic shock is a process accompanied by reduced serum levels of Ang2. These findings add significantly to our understanding of that experimental treatment strategy of resuscitation.

Serum of patients with septic shock stimulates the expression of Trem-1 on U937 monocytes

OBJECTIVES

To describe the concentrations of sTREM-1 in patients with sepsis and to explore the effects of their serum on the expression of TREM-1 on U937 monocytes.

METHODS

Blood was sampled at regular time intervals in 56 patients with sepsis. Concentrations of tumour necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1alpha), IL-6, IL-8, IL-10 and IL-12p70 and sTREM-1 were measured. U937 monocytes were incubated in the presence of serum at sepsis onset.

RESULTS

Median sTREM-1 concentration on day 1 for patients with septic shock was 915 pg/ml and 228.5 pg/ml for those without shock (p = 0.002). TNFalpha, IL-1alpha, IL-6, IL-8 and IL-10 did not differ between them. A positive correlation was found between changes of sTREM-1 and SOFA scores from day 1 to 7. Sera of patients with septic shock evoked a significant increase of the expression of TREM-1. The concentrations of TNFalpha and IL-8 in supernatants increased only after stimulating with sera of patients without shock, but not after stimulating with sera of patients with shock.

CONCLUSIONS

Levels of sTREM-1 correlated with sepsis severity. sTREM-1 is considerably higher in patients with shock compared to patients without shock. The serum of shocked patients could stimulate the expression of TREM-1 on U937 monocytes.

The level of hypotension during hemorrhagic shock is a major determinant of the post-resuscitation systemic inflammatory response: an experimental study

Background

To evaluate whether the level of hypotension during hemorrhagic shock may influence the oxidative and inflammatory responses developed during post-ischemic resuscitation.

Methods

Fifteen rabbits were equally allocated into three groups: sham-operated (group sham); bled within 30 minutes to mean arterial pressure (MAP) of 40 mmHg (group shock-40); bled within 30 minutes to MAP of 30 mmHg (group shock-30). Shock was maintained for 60 min. Resuscitation was performed by reinfusing shed blood with two volumes of Ringer's lactate and blood was sampled for estimation of serum levels aminotransferases, creatinine, TNF-α, IL-1β, IL-6, malondialdehyde (MDA) and total antioxidant status (TAS) and for the determination of oxidative burst of polymorhonuclears (PMNs) and mononuclear cells (MCs).

Results

Serum AST of group shock-30 was higher than that of group shock-40 at 60 and 120 minutes after start of resuscitation; serum creatinine of group shock-30 was higher than group shock-40 at 120 minutes. Measured cytokines, MDA and cellular oxidative burst of groups, shock-40 and shock-30 were higher than group sham within the first 60 minutes after start of resuscitation. Serum concentrations of IL-1β, IL-6 and TNF-α of group shock-30 were higher than group shock-40 at 120 minutes (p < 0.05). No differences were found between two groups regarding serum MDA and TAS and oxidative burst on PMNs and MCs but both groups were different to group sham.

Conclusion

The level of hypotension is a major determinant of the severity of hepatic and renal dysfunction and of the inflammatory response arising during post-ischemic hemorrhagic shock resuscitation. These findings deserve further evaluation in the clinical setting.

Plasma pro- and anti-inflammatory cytokine levels and outcome prediction in unselected critically ill patients

PURPOSE

To determine the inter-relationships between cytokine levels and physiological scores in predicting outcome in unselected, critically ill patients.

METHODS

To this end, 127 patients (96 men), having a mean+/-SD age of 45+/-20 years, with a wide range in admission diagnoses (medical, surgical, and multiple trauma patients) were prospectively investigated. Severity of critical illness and organ dysfunction were graded by acute physiology and chronic health evaluation (APACHE II) and sequential organ failure assessment (SOFA) scores, respectively. Blood samples were drawn on admission in the ICU to determine pro- and anti-inflammatory cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, and IL-10. The main outcome measure was 28-day mortality.

RESULTS

Overall, 88 patients survived and 39 patients died. Univariate logistic regression analysis showed that SOFA, APACHE II, IL-8, IL-6, and IL-10 on admission in the ICU were related to mortality. Multiple logistic regression analysis in the entire cohort of critically ill patients revealed that SOFA (OR=1.341, p<0.001) and IL-6 (OR=1.075, p=0.01) constituted independent outcome predictors. receiver operator characteristics curve analysis showed that SOFA, APACHE II, and IL-6 had the highest area under the curve values. IL-6 correlated with APACHE II (r(s)=0.44, p<0.0001) and SOFA (r(s)=0.40, p<0.0001) scores.

CONCLUSIONS

In mixed ICU patients cytokine concentrations on admission in the ICU represent independent outcome predictors in the presence of disease severity scores.

Grouping of patients with common variable immunodeficiency based on immunoglobulin biosynthesis: comparison with a classification system on CD4-naïve cells

The present study compared two different systems of classification of patients with common variable immunodeficiency (CVID); one based on in vitro immunoglobulin biosynthesis; and another on CD4-naïve cell counts. Peripheral blood mononuclear cells (PBMCs) were isolated from 35 patients with CVID and 20 healthy controls. They were stimulated for the secretion of IgM and IgG after stimulation with Staphylococcus aureus Cowan I (SAC) upon supplementation of interleukin-2 (IL-2) or with pokeweed mitogen. T cell subsets were estimated by flow cytometry. By the first system, patients were classified into group A (n=18) with secretion of neither IgG nor IgM; into group B (n=12) with detectable IgM but no IgG secretion; and into group C (n=5) with IgM and IgG secretion similar to controls. By the second system, patients were classified into group I (n=12) with less than 109 CD4-naïve cells/mul; into group II (n=12) with CD4-naïve cells within 109-225microl(-1); and into group III (n=11) with more than 225 CD4-naïve cells/mul. All groups I-III were defective for in vitro release of IgG and IgM. The likelihood ratio for splenomegaly in patients with <225 CD4-naïve cells/mul was 5.08 (p: 0.024). CD4-naïve cell counts of patients were positively correlated to serum levels of IgG and IgA of patients. The presented results revealed that the former system described adequately the function of B cells and the latter the clinical status of the patient. Our proposal is that both should be used for the characterization of patients with CVID.

Stimulation of monocytes is a pathway involved in systemic inflammatory response following haemorrhagic shock resuscitation: the effect of hypoxaemic resuscitation

The present study was designed to investigate whether serum of animals subjected to hypoxaemic resuscitation from haemorrhagic shock may be a weak stimulant for monocytes or not. Twenty rabbits were subjected to haemorrhagic shock after blood exsanguination; resuscitation was performed by infusion of the shed blood in eight rabbits under normoxaemic conditions (NormoxRes) and in 12 under hypoxaemic conditions (HypoxRes); seven rabbits were subjected to sham operation. Malondialdehyde (MDA) and tumour necrosis factor (TNF)-alpha were estimated in serum at serial time intervals; the serum was applied for stimulation of U937 monocytes with or without the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580. Expression of triggering receptor expressed on myeloid cells-1 (TREM-1) on U937 was also assessed by flow cytometric analysis. Death supervened in four animals of the NormoxRes (50%) and in one animal of the HypoxRes group (8.33%, P: 0.032). Serum levels of TNF-alpha and MDA were higher in NormoxRes compared to HypoxRes animals. Expression of TREM-1 on U937 monocytes was similar after stimulation with serum sampled from both groups. Concentrations of interleukin (IL)-1beta, IL-6 and IL-8 of monocyte supernatants were higher after stimulation with serum of NormoxRes than HypoxRes rabbits. Production of cytokines after stimulation with serum was decreased significantly after addition of SB203580. It is concluded that stimulation of monocytes may contribute to the generation of the systemic inflammatory response during reperfusion after ischaemia. Lower stimulation of the p38 MAPK-mediated production of IL-1beta, IL-6 and IL-8 by monocytes may be implicated as an explanation for the benefits shown for the host when resuscitation is performed under hypoxaemic conditions.

Pituitary-adrenal responses to human corticotropin-releasing hormone in critically ill patients

OBJECTIVE

To investigate the pattern of pituitary-adrenal responses to human corticotropin-releasing hormone (hCRH) in critically ill patients and to examine the relation between responses and clinical outcome.

DESIGN AND SETTING

Prospective study in consecutive critically ill patients in a general intensive care unit in a teaching hospital.

PATIENTS

The study included 37 critically ill, mechanically ventilated patients with diverse underlying diagnoses (28 men, 9 women; median age 56 years).

INTERVENTIONS

A morning blood sample was obtained to measure baseline cortisol, corticotropin (ACTH), and cytokines. Patients were then injected with 100 microg hCRH, and plasma cortisol and ACTH were measured over a period of 2 h.

MEASUREMENTS AND RESULTS

In the overall patient population baseline and peak cortisol concentrations following hCRH were 16+/-5 and 21+/-5 microg/dl, respectively, and median baseline and peak ACTH levels 23 and 65 pg/ml, respectively. Higher ACTH levels and longer release of cortisol were noted in nonsurvivors (n=18) than in survivors (n=19). Furthermore, nonsurvivors had higher concentrations of interleukin 8 (115 vs. 38 pg/ml) and interleukin 6 (200 vs. 128 pg/ml) than survivors.

CONCLUSIONS

Critically ill patients demonstrate altered pituitary-adrenal axis responses to hCRH. This is particularly evident in the sickest patients with the highest degree of inflammatory profile who ultimately do not survive.

Neutrophil CD64 expression and serum IL-8: Sensitive early markers of severity and outcome in sepsis

The aim of the present study was to investigate which biomarker/s reliably assess severity and mortality early in the sepsis process. In 47 critically-ill patients within the 24h of septic onset, Interleukins (IL)-8, -1beta, -6, -10, and -12p70, tumor necrosis factor-alpha (TNF-alpha), procalcitonin (PCT) and C-reactive protein (CRP) were measured in serum. Additionally, CD64 expression was measured in neutrophils. In early sepsis, neutrophil CD64 expression and IL-8 levels are the only biomarkers that increased with sepsis severity, differentiating disease stages: sepsis, severe sepsis and septic shock (p<0.001). The biomarkers that best evaluate the severity of sepsis (via APACHE II) were CD64, IL-8 and IL-6 (p<0.01), and the severity of organ failure (via SOFA) were CD64 and IL-8 (p<0.01). CD64 expression and IL-8 levels were associated with mortality within 28-days (OR=1.3, p=0.01 for CD64 and OR=1.26, p=0.024 for IL-8 by logistic regression analysis) and ROC curve analysis showed high sensitivity and specificity for predicting sepsis stages and the 28 day mortality. We conclude that there is an early increase of neutrophil CD64 expression and IL-8 levels during sepsis. Based on this single measurement it is possible to reliably assess the stage, detect the severity and predict the 28-day mortality of sepsis.

The effect of hypoxemic resuscitation of hemorrhagic shock on hemodynamic stabilization and inflammatory response: a pilot study in a rat experimental model

BACKGROUND

Resuscitation of hemorrhagic shock is associated with tissue injury. The effect of hypoxemia during resuscitation was investigated.

METHODS

Shock was induced by withdrawing blood to mean arterial pressure (MAP) 40 mm Hg and maintained for 60 minutes in 25 Wistar rats. Animals were randomly divided to receive either normoxemic (controls, FiO2 = 21%, n = 14) or hypoxemic (HypRes, FiO2 = 12%, n = 11) resuscitation by re-infusing their shed blood. Outcome was assessed through hemodynamic and inflammatory parameters. Another nine rats served to correlate different FiO2 to the corresponding PaO2.

RESULTS

At 60 minutes of resuscitation HypRes had higher MAP than control animals (p = 0.008). The respective median (range) malondialdehyde and TNF-alpha levels was 1.7 (1-2.1) versus 3.1 (2.4-4.3) micromol/L, (p = 0.02) and 0 versus 5.8 (0-5.8) pg/mL, (p = 0.025). Glutathione, endotoxin, interferon-gamma, and nitric oxide values were similar between groups. FiO2 of 12% induced only a mild hypoxemia (PaO2 approximately 80 mm Hg).

CONCLUSIONS

Even mild hypoxemia during resuscitation of shock leads to effective hemodynamic stabilization.