A pilot study to explore patterns and predictors of delayed kidney decline after cardiopulmonary bypass.

There is no current consensus on the follow up of kidney function in patients undergoing cardiopulmonary bypass (CPB). The main objectives of this pilot study is to collect preliminary data on kidney function decline encountered on the first postoperative visit of patients who have had CPB and to identify predictors of kidney function decline post hospital discharge. Design: Retrospective chart review. Adult patients undergoing open heart procedures utilizing CPB. Patient demographics, type of procedure, pre-, intra-, and postoperative clinical, hemodynamic echocardiographic, and laboratory data were abstracted from electronic medical records. Acute kidney disease (AKD), and chronic kidney disease (CKD) were diagnosed based on standardized criteria. Interval change in medications, hospital admissions, and exposure to contrast, from hospital discharge till first postoperative visit were collected. AKD, and CKD as defined by standardized criteria on first postoperative visit. 83 patients were available for analysis. AKD occurred in 27 (54%) of 50 patients and CKD developed in 12 (42%) out of 28 patients. Older age was associated with the development of both AKD and CKD. Reduction in right ventricular cardiac output at baseline was associated with AKD (OR: 0.5, 95% CI: 0.3, 0.79, P = 0.01). Prolongation of transmitral early diastolic filling wave deceleration time was associated with CKD (OR: 1.02, 95% CI: 1.01, 1.05, P = 0.03). In-hospital acute kidney injury (AKI) was a predictor of neither AKD nor CKD. AKD and CKD occur after CPB and may not be predicted by in-hospital AKI. Older age, right ventricular dysfunction and diastolic dysfunction are important disease predictors. An adequately powered longitudinal study is underway to study more sensitive predictors of delayed forms of kidney decline after CPB.

The effect of procedural end-tidal CO2 on infarct expansion during anterior circulation thrombectomy.

BACKGROUND: Carbon dioxide is a potent cerebral vasodilator that may influence outcomes after ischemic stroke. The objective of this study was to investigate the effect of intraprocedural mean end-tidal CO2 (ETCO2) levels on core infarct expansion and neurologic outcome following thrombectomy for anterior circulation ischemic stroke. METHODS: A retrospective review was conducted of consecutive patients from March 2020 to June 2021 who underwent mechanical thrombectomy for acute anterior circulation ischemic stroke under general anesthesia and achieved successful recanalization (Thrombolysis in Cerebral Infarction [TICI] ≥ 2b). Only patients with CT perfusion, procedural ETCO2, and postoperative MRI data were included. Segmentation software was used for multi-parametric image analysis. Normocarbia defined as mean ETCO2 of 35 mmHg was used to dichotomize subjects. Univariate and multivariate statistics were applied. RESULTS: Fifty-eight patients met criteria for analysis. Of these, 44 had TICI 3 recanalization, 9 had TICI 2c, and 5 had TICI 2b. Within this combined recanalization group, patients with mean ETCO2 > 35 had significantly higher rates of functional independence at 90 days. Although patients tended to salvage more penumbra and experience smaller final infarcts when ETCO2 exceeded 35 mmHg, this did not reach statistical significance. CONCLUSIONS: Stroke patients who underwent successful thrombectomy with general anesthesia achieved higher rates of functional independence when procedural ETCO2 exceeded 35 mmHg. Further studies to confirm this effect and investigate optimal ETCO2 parameters should be considered.

Haplotype analysis of SERPINE1 gene: Risk for aneurysmal subarachnoid hemorrhage and clinical outcomes.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) has high fatality and permanent disability rates due to the severe damage to brain cells and inflammation. The SERPINE1 gene that encodes PAI-1 for the regulation of tissue plasminogen activator is considered an important therapeutic target for aSAH. METHODS: Six SNPs in the SERPINE1 gene (in order of rs2227631, rs1799889, rs6092, rs6090, rs2227684, rs7242) were investigated. Blood samples were genotyped with Taqman genotyping assays and pyrosequencing. The experiment-wide statistically significant threshold for single marker analysis was set at p < 0.01 after evaluation of independent markers. Haplotype analysis was performed in Haplo.stats package with permutation tests. Bonferroni correction for multiple comparison in dominant, additive, and recessive model was applied. RESULTS: A total of 146 aSAH patients and 49 control subjects were involved in this study. The rs2227631 G allele is significant (p = 0.01) for aSAH compared to control. In aSAH group, haplotype analysis showed that G5GGGT homozygotes in recessive model were associated with delayed cerebral ischemia (p < 0.01, Odds Ratio = 5.14, 95% CI = 1.45-18.18), clinical vasospasm (p = 0.01, Odds Ratio = 4.58, 95% CI = 1.30-16.13), and longer intensive care unit stay (p = 0.01). By contrast, the G5GGAG carriers were associated with less incidence of cerebral edema (p < 0.01) and higher Glasgow Coma Scale (p < 0.01). The A4GGGT carriers were associated with less incidence of severe hypertension (>140/90) (p < 0.01). CONCLUSION: The results suggested an important regulatory role of the SERPINE1 gene polymorphism in clinical outcomes of aSAH.

Respiratory oxygen uptake is associated with survival in a cohort of ventilated trauma and burn patients.

BACKGROUND: Little data is available in the literature about the role of end tidal oxygen in critically ill patients. We sought to identify the association between the level of respiratory oxygen and clinical outcomes in critically-ill ventilated trauma and burn patients. METHODS: A retrospective cohort of 55 trauma and burn patients from 2010 to 2016 was collected. Exposures of interest included a) expiratory end tidal oxygen (ETO2) and b) the difference between FiO2 and ETO2 (uptake). Associations of clinical characteristics with ETO2 and oxygen uptake were examined using a Spearman correlation. The relationships between discharge status, demographics, injury type, severity, and clinical characteristics were examined using chi-square (or Fisher's exact) tests and two-sample t-tests. Multivariable analyses using linear and logistic regression were performed to determine whether expiratory end tidal oxygen or oxygen uptake was an independent predictor of clinical outcomes. RESULTS: Mean age for the patients was 46.3±18.2years with 41 (74.6%) male and 34 (61.8%) white. In the cohort, 27 (49.1%) of patients had burns and 28 (50.9%) blunt trauma. Oxygen uptake was negatively correlated with lactic acid, minute ventilation, total ICU days, and ventilator days (p<0.05). Patients who died demonstrated lower oxygen uptake than those alive, oxygen uptake remained significantly associated with discharge status after adjusting for potential confounders (p=0.028). CONCLUSION: A narrowed difference between ETO2 and inspiratory oxygen is associated with increased mortality in a cohort of ventilated trauma and burn patients. Future research is needed to further elucidate the role of respiratory oxygen level in larger, prospective studies.

Association of cystathionine beta-synthase polymorphisms and aneurysmal subarachnoid hemorrhage.

OBJECTIVE Cystathionine ß-synthase (CBS) is involved in homocysteine and hydrogen sulfide (H2S) metabolism. Both products have been implicated in the pathophysiology of cerebrovascular diseases. The impact of CBS polymorphisms on aneurysmal subarachnoid hemorrhage (aSAH) and its clinical sequelae is poorly understood. METHODS Blood samples from all patients enrolled in the CARAS (Cerebral Aneurysm Renin Angiotensin System) study were used for genetic evaluation. The CARAS study prospectively enrolled aSAH patients at 2 academic institutions in the United States from 2012 to 2015. Common CBS polymorphisms were detected using 5'exonuclease genotyping assays. Analysis of associations between CBS polymorphisms and aSAH was performed. RESULTS Samples from 149 aSAH patients and 50 controls were available for analysis. In multivariate logistic regression analysis, the insertion allele of the 844ins68 CBS insertion polymorphism showed a dominant effect on aSAH. The GG genotype of the CBS G/A single nucleotide polymorphism (rs234706) was independently associated with unfavorable functional outcome (modified Rankin Scale Score 3-6) at discharge and last follow-up, but not clinical vasospasm or delayed cerebral ischemia (DCI). CONCLUSIONS The insertion allele of the 844ins68 CBS insertion polymorphism was independently associated with aSAH while the GG genotype of rs234706 was associated with an unfavorable outcome both at discharge and last follow-up. Increased CBS activity may exert its neuroprotective effects through alteration of H2S levels, and independent of clinical vasospasm and DCI.

Associations between endothelin polymorphisms and aneurysmal subarachnoid hemorrhage, clinical vasospasm, delayed cerebral ischemia, and functional outcome.

OBJECTIVE Endothelin-1, a potent vasoconstrictor, and its receptors may be involved in the pathogenesis of aneurysmal subarachnoid hemorrhage (aSAH), clinical vasospasm, delayed cerebral ischemia (DCI), and functional outcome following aSAH. In the present study, common endothelin single nucleotide polymorphisms (SNPs) and their relation to aSAH were evaluated. METHODS Blood samples from all patients enrolled in the Cerebral Aneurysm Renin Angiotensin System (CARAS) study were used for genetic evaluation. The CARAS study prospectively enrolled patients with aSAH at 2 academic institutions in the US from 2012 to 2015. Common endothelin SNPs were detected using 5' exonnuclease (TaqMan) genotyping assays. Analysis of associations between endothelin SNPs and aSAH and its clinical sequelae was performed. RESULTS Samples from 149 patients with aSAH and 50 controls were available for analysis. In multivariate logistic regression analysis, the TG (odds ratio [OR] 2.102, 95% confidence interval [CI] 1.048-4.218, p = 0.036) and TT genotypes (OR 7.884, 95% CI 1.003-61.995, p = 0.05) of the endothelin-1 T/G SNP (rs1800541) were significantly associated with aSAH. There was a dominant effect of the G allele (CG/GG genotypes; OR 4.617, 95% CI 1.311-16.262, p = 0.017) of the endothelin receptor A G/C SNP (rs5335) on clinical vasospasm. Endothelin SNPs were not associated with DCI or functional outcome. CONCLUSIONS Common endothelin SNPs were found to be associated with presentation with aSAH and clinical vasospasm. Further studies are required to elucidate the relevant pathophysiology and its potential implications in the treatment of patients with aSAH.

The role of endothelial nitric oxide synthase -786 T/C polymorphism in cardiac instability following aneurysmal subarachnoid hemorrhage.

INTRODUCTION: Cardiac abnormalities are observed frequently after aneurysmal subarachnoid hemorrhage (aSAH). A subset of aSAH patients develops neurogenic cardiomyopathy, likely induced by catecholamine excess. Genetic polymorphisms of the endothelial nitric oxide synthase (eNOS) gene have been linked to decreased nitric oxide (NO) levels, coronary artery spasm, and myocardial infarction. The role of the eNOS single nucleotide polymorphism (SNP) -786 T/C in cardiac instability following aSAH has not been previously investigated. METHODS: From 2012 to 2015, aSAH patients were prospectively enrolled in the Cerebral Aneurysm Renin Angiotensin System (CARAS) study at two academic institutions. Blood samples were used to assess the eNOS SNP -786 T/C rs2070744 through 5'exonuclease (Taqman) genotyping assays. Associations between this polymorphism and cardiac instability following aSAH were analyzed. RESULTS: Multivariable analysis demonstrated a dominant effect of the C allele of eNOS SNP -786 T/C on cardiac instability in patients with aSAH. A lower Glasgow Coma Scale score and a history of ischemic vascular disease were also associated with cardiac instability. Furthermore, cardiac instability independently predicted poor functional outcome upon discharge from the hospital. CONCLUSIONS: The C allele of the eNOS SNP -786 T/C was independently associated with an increased risk for cardiac instability following aSAH. Cardiac instability itself was a risk factor for an unfavorable functional outcome upon discharge from the hospital.

Association of Plasminogen Activator Inhibitor 1 (SERPINE1) Polymorphisms and Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Genetic variations of the serine proteinase inhibitor family E member 1 (SERPINE1) gene, which encodes plasminogen activator inhibitor 1, correlate with serum levels of its product and are associated with thrombophilia and coronary atherosclerosis. Various SERPINE1 ;gene polymorphisms have been identified. However, only the functional 5G/4G polymorphism has been assessed in the context of aneurysmal subarachnoid hemorrhage (aSAH). We assessed associations of 6 SERPINE1 polymorphisms with the clinical sequelae of aSAH. METHODS: From 2012 to 2015, patients with aSAH were prospectively enrolled into the CARAS (Cerebral Aneurysm Renin Angiotensin System) study at 2 major academic institutions. Blood samples were used to evaluate 6 common SERPINE1 single nucleotide polymorphisms via 5' exonuclease (Taqman) genotyping assays. RESULTS: There was an association of the AA genotype of rs2227631 with the 4G/4G genotype and of the GG genotype of rs7242 with the AA genotype of rs2227684. In multivariable analysis, patients with the AA genotype of rs2227631 and 4G/4G genotype had an increased risk for developing delayed cerebral ischemia. Patients with the GG genotype of rs7242 and AA genotype of rs2227684 had a decreased risk for a poor functional outcome. CONCLUSIONS: SERPINE1 gene polymorphisms were associated with delayed cerebral ischemia and functional outcome after aSAH. These associations may arise from alterations of plasminogen activator inhibitor 1 levels.

Endothelin polymorphisms as a risk factor for cerebral aneurysm rebleeding following aneurysmal subarachnoid hemorrhage.

BACKGROUND: Aneurysm rebleeding following presentation with aneurysmal subarachnoid hemorrhage (aSAH) is associated with high mortality and poor functional outcome. While a substantial genetic contribution to aneurysm formation and rupture is known, the genetic influence on the risk of rebleeding is poorly understood. OBJECTIVE: To evaluate the role of common endothelin polymorphisms in aneurysm rebleeding. PATIENTS AND METHODS: Blood sample from all patients enrolled in the CARAS (Cerebral Aneurysm Renin Angiotensin System) study were used for genetic evaluation. The CARAS study prospectively enrolled aSAH patients at two academic institutions in the United States from 2012 to 2015. Common endothelin SNPs were detected using 5'exonnuclease (Taqman) genotyping assays. Analysis of associations between endothelin single nucleotide polymorphisms (SNP) and aneurysm rebleeding was performed. RESULTS: One hundred and forty-nine aSAH patients were included. Acute spontaneous aneurysm rebleeding occurred in 5 (3.4%) patients. Multivariable analysis identified the TT genotype for EDN1 G/T SNP (rs2070699; OR 97.4, 95% CI 3.825-2479.984, p=0.006) as an independent risk factor for aneurysm rebleeding. Aneurysm rebleeding was associated with an unfavorable functional outcome (mRS 3-6) at last follow up in all 5 patients. CONCLUSION: Aneurysm rebleeding following presentation with aSAH was independently associated with the TT genotype of the EDN1 G/T SNP. All patients with acute spontaneous aneurysm rebleeding suffered a poor functional outcome at last follow up.

Endothelial Nitric Oxide Synthase Polymorphism Is Associated with Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: Nitric oxide is critical in the regulation of cerebral blood flow and smooth muscle proliferation. It is synthesized by 3 nitric oxide synthase (NOS) isoforms: neuronal, inducible, and endothelial NOS (eNOS). Aneurysmal subarachnoid hemorrhage (aSAH) causes endothelial dysfunction that, in turn, contributes to pathophysiologic processes surrounding aSAH. Previous studies reported an association of an eNOS single nucleotide polymorphism (SNP) with the clinical sequelae of aSAH. Here, we further elucidate the impact of this eNOS SNP on the clinical course after aSAH. METHODS: The Cerebral Aneurysm Renin Angiotensin System study prospectively enrolled aSAH patients at 2 academic institutions in the United States from 2012-2015. Blood samples from all patients enrolled in the study were used for genetic evaluation using 5'exonuclease (Taqman) genotyping assays. Associations between the eNOS SNP rs2070744 (786 T->C) and clinical course after aSAH were analyzed. RESULTS: Samples from 149 aSAH patients were available for analysis. The C allele of the eNOS SNP independently predicted an increased risk for delayed cerebral ischemia (OR = 2.936, 95% CI 1.048-8.226, P = 0.040). The eNOS SNP rs2070744 was not associated with functional outcome or size of aneurysm at the time of rupture. CONCLUSIONS: The present study is the first to demonstrate that the C allele of the eNOS SNP 786 T->C rs2070744 is independently associated with an increased risk for delayed cerebral ischemia following aSAH.

Associations of Endothelin Polymorphisms and Aneurysm Size at Time of Rupture.

BACKGROUND AND PURPOSE: Aneurysm size is an important risk factor for aneurysm rupture. The pathophysiologic mechanisms underlying aneurysm growth remain poorly understood. Endothelin signaling is critical for cerebrovascular blood flow regulation. The influence of endothelin single nucleotide polymorphisms (SNPs) on aneurysm size at the time of rupture has not been previously investigated. METHODS: Eight common endothelin SNPs were assessed using blood samples from aneurysmal subarachnoid hemorrhage (aSAH) patients enrolled in the Cerebral Aneurysm Renin Angiotensin System study, a prospective, 2-center study that enrolled aSAH patients and controls in the United States from 2012-2015. Genetic evaluation was performed using 5'exonnuclease (Taqman) genotyping assays. Associations of endothelin SNPs and aneurysm size were analyzed. RESULTS: One-hundred and forty-nine blood samples from aSAH patients were available for analysis. There was a dominant effect of the G allele of the endothelin receptor type A (EDNRA) SNP rs5335 on aneurysm size ≥7 mm (odds ratio = 2.740, 95% confidence interval 1.039-7.228, P = 0.042) along with associations with race and presence of additional aneurysms. The other endothelin SNPs were not associated with aneurysm size. CONCLUSIONS: The EDNRA SNP rs5335 was independently associated with aneurysms ≥7 mm in size at the time of rupture. Patients with cerebral aneurysms also carrying the G allele of EDNRA SNP rs5335 may develop larger aneurysms before rupture.

Impact of High-Mobility Group Box 1 Polymorphism on Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND AND OBJECTIVE: The high-mobility group box 1 (HMGB1) protein is a eukaryotic, ubiquitously expressed protein that serves as a biomarker for various diseases and is involved in the promotion of a proinflammatory response to cell injury. In aneurysmal subarachnoid hemorrhage (aSAH), increased HMGB1 levels have been linked to poor outcome and an increased risk for cerebral vasospasm. The role of HMGB1 polymorphisms in aSAH has not been previously investigated. METHODS: Patients with aSAH and controls enrolled in the prospective, 2-center CARAS (Cerebral Aneurysm Renin Angiotensin System) study were evaluated. The 3814 C/G HMGB1 single nucleotide polymorphism (SNP) rs2249825 was detected using 5'exonuclease (Taqman) genotyping assays from blood samples from patients with aSAH and controls. Associations between aSAH and its clinical sequelae with the HMGB1 SNP were assessed. RESULTS: Samples from 149 patients with aSAH and 50 controls were available for analysis. No increased risk for aSAH associated with the SNP was found compared with the control group. Delayed cerebral ischemia (DCI) was defined as a cerebral infarction at the time of discharge from the intensive care unit and identified in 21.2% of patients with aSAH. In multivariable logistic regression analysis, the G allele of rs2249825 was independently associated with DCI (odds ratio, 5.695; 95% confidence interval, 1.804-17.975; P = 0.003). CONCLUSIONS: The minor allele G of rs2249825 was associated with an increased risk for DCI, or cerebral infarction, after aSAH. This finding may be attributable to an increased HMGB1 protein expression in these patients.

Ryanodine Receptor 1 Polymorphism Is Not Associated with Aneurysmal Subarachnoid Hemorrhage or its Clinical Sequelae.

OBJECTIVE: The pathophysiologic mechanisms underlying cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) remain poorly understand. Ryanodine receptors (RYR) are intracellular calcium channels involved in the regulation of vascular smooth muscle cells and cerebrovascular tone and diameter. Previous work reported an association between an RYR polymorphism and cerebral vasospasm. Here, we sought to assess the impact of that RYR polymorphism on aSAH and its clinical sequelae. METHODS: Blood samples from all patients enrolled in the CARAS (Cerebral Aneurysm Renin Angiotensin System) study were used for genetic evaluation. The RYR1 single nucleotide polymorphism (SNP) rs35364374 was detected using 5'exonuclease (Taqman) genotyping assays. Associations between the RYR1 polymorphism and aSAH and its clinical sequelae were analyzed. RESULTS: Samples from 149 patients with aSAH and 50 controls were available for analysis. Multivariable regression analysis did not show an association of RYR1 SNP rs35364374 with aSAH. Moreover, there was no association of RYR1 SNP rs35364374 with clinical vasospasm, delayed cerebral ischemia, functional outcome at discharge, or functional outcome at last follow-up. CONCLUSIONS: Contrary to a previous report, the RYR1 SNP rs35364374 was not associated with aSAH or its clinical sequelae.

Effect of progressive mandibular advancement on pharyngeal airway size in anesthetized adults.

BACKGROUND: General anesthesia in adult humans is associated with narrowing or complete closure of the pharyngeal airway. The purpose of this study was to determine the effect of progressive mandibular advancement on pharyngeal airway size in normal adults during intravenous infusion of propofol for anesthesia. METHODS: Magnetic resonance imaging was performed in nine normal adults during wakefulness and during propofol anesthesia. A commercially available intraoral appliance was used to manually advance the mandible. Images were obtained during wakefulness without the appliance and during anesthesia with the participants wearing the appliance under three conditions: without mandibular advancement, advancement to 50% maximum voluntary advancement, and maximum advancement. Using computer software, airway area and maximum anteroposterior and lateral airway diameters were measured on the axial images at the level of the soft palate, uvula, tip of the epiglottis, and base of the epiglottis. RESULTS: Airway area across all four airway levels decreased during anesthesia without mandibular advancement compared with airway area during wakefulness (P < 0.007). Across all levels, airway area at 50% advancement during anesthesia was less than that at centric occlusion during wakefulness (P = 0.06), but airway area with maximum advancement during anesthesia was similar to that during wakefulness (P = 0.64). In general, anteroposterior and lateral airway diameters during anesthesia without mandibular advancement were decreased compared with wakefulness and were restored to their wakefulness values with 50% and/or maximal advancement. CONCLUSIONS: Maximum mandibular advancement during propofol anesthesia is required to restore the pharyngeal airway to its size during wakefulness in normal adults.

Inhaled nitric oxide attenuates reperfusion inflammatory responses in humans.

BACKGROUND: Reduced bioavailability of endothelium-derived nitric oxide associated with reperfusion could potentially exacerbate the inflammatory response during reperfusion. Evidence suggests the pharmacologic effects of inhaled nitric oxide may extend beyond the pulmonary vasculature, and this is attributed to nitric oxide-derived complexes in blood that ultimately orchestrate antiinflammatory effects. In this study, the authors evaluated the potential for inhaled nitric oxide (80 ppm) to attenuate inflammation instigated by ischemia-reperfusion in a human model using patients undergoing knee surgery where a tourniquet was used to produce a bloodless surgical field. METHODS: Inhaled nitric oxide (80 ppm) was administered before tourniquet application and continued throughout reperfusion until the completion of surgery. Venous blood samples were collected before and after reperfusion, for the measurements of nitrate and nitrite, CD11b/CD18, soluble P-selectin, and lipid hydroperoxide. Muscle biopsies were obtained from the quadriceps muscle before skin closure and analyzed for myeloperoxide, conjugated dienes, and nuclear factor-kappaB translocation. RESULTS: Administration of inhaled nitric oxide (80 ppm) significantly attenuated the inflammatory response characterized by reduced expression of CD11b/CD18, P-selectin, and nuclear factor kappaB compared with the control group. This was accompanied by increased plasma levels of nitrate and nitrite and reduced oxidative stress. CONCLUSIONS: Administration of inhaled nitric oxide at 80 ppm significantly reduces inflammation in lower extremity ischemia-reperfusion in humans. This observation supports the concept that during diseases characterized by dysfunction in nitric oxide metabolism, inhaled nitric oxide may be an effective therapy to replenish systemic nitric oxide, thus retarding inflammatory-mediated injury.

Splanchnic oxygen consumption is impaired during severe acute normovolemic anemia in anesthetized humans.

BACKGROUND: In conscious humans, reduction in hemoglobin concentration to 5 g/dl did not produce inadequate systemic oxygenation. However, systemic measures of inadequate oxygenation may not be sufficiently sensitive to detect inadequate oxygenation in individual organs such as splanchnic organs. The authors tested the hypothesis that acute normovolemic anemia to hemoglobin less than 6.0 g/dl in anesthetized humans reduces splanchnic oxygen consumption because of diminished whole body oxygen delivery. METHODS: Elective spine (n = 12) and abdominal (n = 7) surgery patients underwent acute normovolemic anemia to decrease the hemoglobin concentration close to 6.0 g/dl. The authors assessed the development of supply-dependent conditions in systemic and regional vascular beds by two primary measures before and after acute normovolemic anemia: oxygen consumption and surrogate biochemical markers of anaerobic metabolism, including plasma lactate, regional lactate kinetics, and ketone body ratio. RESULTS: When hemoglobin was reduced from 13.6 +/- 1.2 to 5.9 +/- 0.3 g/dl, oxygen supply dependency occurred in the splanchnic and preportal tissues but not at the systemic level. Regional supply dependency was accompanied by biochemical markers of anaerobic metabolism. CONCLUSIONS: In anesthetized humans, a reduction in hemoglobin to 5.9 g/dl by acute normovolemic anemia diminished splanchnic and preportal whole body oxygen delivery and impaired splanchnic and preportal oxygen consumption. This was accompanied by increased plasma levels of regional lactate and an increased beta-hydroxybutyrate-to-acetoacetate ratio. These findings suggest that the risk to the gastrointestinal tract during acute normovolemic anemia may be underestimated.

Left ventricular diastolic filling characteristics are not impaired but systolic performance was augmented in the early hours of experimental endotoxemia in humans.

This study was performed to determine whether endotoxemia causes diastolic cardiac dysfunction. Eleven healthy volunteers, 30 +/- 6 years of age, underwent comprehensive transthoracic echocardiographic assessment including two-dimensional, M-mode transmitral and tissue Doppler of systolic and diastolic function at baseline and at 3 and 5 h after intravenous administration of purified Escherichia coli endotoxin (4 ng/kg). Data were analyzed by analysis of variance; P values of less than 0.05 were considered significant. Endotoxin administration resulted in a hyperdynamic state characterized by decreased mean arterial pressure and significant increase in cardiac index. This was accompanied by increases in several load-dependent systolic performance indices (3 and 5 h). Robust increases in peak systolic blood pressure/end-systolic volume index, one of the relatively load-independent contractility parameter, were also observed at 3 h after endotoxin administration. Transmitral peak early velocity (E), which represents early filling, significantly increased at 3 h after infusion. Late diastolic velocity (A), which represents atrial contraction, significantly increased at 3 and 5 h after infusion. The E/A ratio indicative of delayed relaxation significantly decreased due to increases in A (transmitral) and A (tissue Doppler) at 3 and 5 h after infusion. As expected, endotoxin infusion resulted in a hyperdynamic state associated with increases in systolic function indices including endocardial systolic velocities. The observed decreases in E/A (transmitral) and E/A (tissue Doppler) ratio were primarily due to increases in A and A. Moreover, isovolumic relaxation time and time constant for left ventricular relaxation, a load-independent parameter for ventricular relaxation, remained unchanged at 3 and 5 h after endotoxin infusion. Therefore, our findings are more likely due to enhanced atrial contractility resulting from increased sympathetic activity in response to reduction in left ventricular afterload and not due to altered diastolic filling characteristics.

Ischemic preconditioning at a distance: altered gene expression in mouse heart and other organs following brief occlusion of the mesenteric artery.

Remote ischemic preconditionining (IPC) has been defined as a brief episode of ischemia/reperfusion in an organ that protects another remote organ from the damage induced by subsequent and prolonged ischemia. As yet, no study has been conducted with the purpose of elucidating a precise association between remote IPC and patterns of gene-transcription in cardiac tissue. In this study, using a cDNA microarray, we analyzed the gene expression profile in murine heart at 24h after brief cycles of occlusion of the superior mesenteric artery. The profile revealed that IPC induces significant levels of expression of many genes known to be associated with the stress response, redox regulation, growth and metabolism, DNA repair and other functions. The result of cDNA microarray profile from heart was also compared with those from other organs (lung, kidney and intestine). The genes identified in the expression profile may be associated with remote IPC induced late phase organ protection.

Endothelial dysfunction in trauma patients: a preliminary communication.

Global ischemia, followed by reperfusion during resuscitation, leads to cellular damage by generating toxic reactive metabolites that includes, but is not exclusive to, superoxide radical. Superoxide decreases the bioavailability of nitric oxide (NO) via its reaction that yields peroxynitrite. The observation of decreased bioavailability of NO, and attenuated endothelium-dependent relaxation have been observed in animal models of trauma and resuscitation. However, it remains unknown whether endothelium-mediated vasodilation is impaired in humans after traumatic hemorrhage followed by crystalloid resuscitation. Based on these previously established precepts, we hypothesized that endothelium-dependent relaxation is impaired in trauma patients despite adequate fluid resuscitation with crystalloid solutions. Baseline characteristics such as age, body mass index, and blood pressure being similar in both groups, NO-mediated, endothelium-dependent flow-mediated dilation (FMD) of the brachial artery was examined in resuscitated trauma victims (n = 13) and compared in normal controls (n = 12). Baseline brachial artery diameter, endothelium-dependent FMD induced by reactive hyperemia and endothelium-independent dilation induced by administration of sublingual nitroglycerin were measured. Brachial artery diameter measured at baseline in trauma patients and in control subjects were not dissimilar. In conclusion, brachial artery FMD, a surrogate for NO-mediated endothelial function, was significantly impaired in trauma patients despite fluid resuscitation resulting in stable hemodynamics (0.8 +/- 1.7 mm vs. 5.7 +/- 0.8 mm, respectively; P < 0.05) However, endothelium-independent dilation induced by nitroglycerin was not significantly different between trauma patients and controls.

Inflammatory and redox responses to ischaemia/reperfusion in human skeletal muscle.

The objective of this study was to identify cellular and plasma marker(s) of post-I/R (ischaemia/reperfusion) in patients undergoing elective knee surgery where a tourniquet was used to facilitate a bloodless surgical field. We evaluated the inflammatory and redox response by measuring the mRNA levels of ICAM-1 (intercellular cell-adhesion molecule-1), MnSOD (manganese superoxide dismutase), GST-mu (glutathione transferase-mu) and Cu/ZnSOD (copper/zinc superoxide dismutase) in the operated muscle and blood cells pre-operatively (pre-tourniquet) and at various times after reperfusion (tourniquet release). We also measured plasma concentrations of IL (interleukin)-6, IL-8, sICAM-1 (soluble ICAM-1), IL-1beta and TNF-alpha (tumour necrosis factor-alpha) using ELISA. Our results show a strong induction of MnSOD and GST-mu in granulocytes (but not in mononuclear cells or muscle) after reperfusion (2 and 4 h). There was no change in the mRNA level of Cu/ZnSOD after reperfusion. An up-regulation of membrane ICAM-1 in muscle and a decrease in sICAM-1 in plasma were detected after reperfusion. Plasma IL-6 and IL-8 levels (but not TNF-alpha or IL-1beta) increased significantly over baseline at 2 and 4 h after reperfusion. Elevated expression of ICAM-1 in muscle, MnSOD and GST-mu in granulocytes and increased levels of plasma IL-6 and IL-8 may be considered as phase- and cell-specific markers of post-I/R of skeletal muscle in humans.