Microproteinuria predicts the severity of systemic effects of reperfusion injury following infrarenal aortic aneurysm surgery

Association of Urinary Albumin:Creatinine Ratio with Outcome of Children with Sepsis

Objective

The aim of the study was to investigate the association of urinary albumin:creatinine ratio (ACR) with regard to the outcome of sepsis patients and to study the trends of ACR with severity of disease, organ dysfunction, microcirculation status, the use of inotrope, and mechanical ventilation use, and length of pediatric intensive care unit (PICU) stay.

Materials and methods

In the prospective observational study, the patients with varying categories of sepsis admitted in the PICU with stay >24 hours were enrolled consecutively. Urine samples were collected at the time of admission (ACR1), 12 hours (ACR2), and 24 hours (ACR3).

Results

One hundred and thirty-eight patients including 56 cases of sepsis, 31 of severe sepsis, 22 of septic shock, and 29 of multiorgan dysfunction syndrome (MODS) cases were analyzed. There were 29 (21%) deaths. ACR (median, IQR) was significantly higher in nonsurvivors [ACR1 198.9 (111.2–329.4) vs 124.5 (59.37–294.5), p 0.03], [ACR2 213.8 (112.5–350) vs 117.8 (62.6–211.9) p 0.008], [ACR3 231.8 (99.9–441.2 vs 114.4 (44.1–240.3), p 0.005]. The ACR is increased progressively with the increasing severity of sepsis (p < 0.001). The performance of ACR operative characteristics was compared with that of PRISM and PELOD scores. In deceased, ACR was significantly correlated with blood pH, lactate, and base deficit. A cutoff value of ACR 102.7 mg/g had sensitivity 86.2%, specificity 40.4%, positive predictive value 27.8%, and negative predictive value 91.7%. The use of inotropes, mechanical ventilation (>48 hours), and mortality was significantly higher in patients with ACR >102 mg/g. The probability of death varied from 17.6 to 19% in the first 24 hours of admission. ACR was significantly cheaper as compared to PRISM score and PELOD score estimations.

Conclusion

Urinary ACR, a cost-effective tool, correlates with the severity of sepsis and associated morbidity and mortality in children.

How to cite this article

Sachdev A, Raheja K, Gupta N, Chugh P. Association of Urinary Albumin:Creatinine Ratio with Outcome of Children with Sepsis. Indian J Crit Care Med 2020;24(6):465–472.

Changes in albuminuria during the spontaneous breathing trial: A prospective observational study

BACKGROUND

We hypothesized urine albumin concentration may detect the early increasing cardiac load during the spontaneous breathing trial (SBT). The purpose of our study is to determine whether the changes in urine albumin concentration before and after the SBT correlate with SBT outcome.

METHODS

This prospective observational study was conducted from January 2013 to September 2013. Patients receiving endotracheal tube intubation due to acute respiratory failure were included. Urine albumin concentration was measured upon admission to the intensive care unit, before and after the SBT.

RESULTS

A total of 211 patients with respiratory failure were screened. Finally, 69 patients were included for analysis. Among the 69 patients received the SBT, 61 patients passed the SBT while 8 patients didn't. Urine albumin concentration upon admission was 251.00 ± 108.21 mg/g in the SBT success group and 260.87 ± 77.95 mg/g in the SBT failure group (p = 0.97). The mean percent change in urine albumin concentration during the SBT was significantly higher in the SBT failure group (+58.44%) than in the SBT success group (+13.11%) (p = 0.02). Univariable and multivariable logistic regression model showed that the difference of urine albumin concentration before and after the SBT correlated significantly with SBT failure (adjusted OR:1.04, p = 0.01).

CONCLUSION

This open label pilot study demonstrates the significant association of the changes in urine albumin concentration with SBT outcome. Further study is warranted to investigate the predictive value of urine albumin concentration.

Avoiding Liver Injury with Papaverine and Ascorbic Acid Due to Infrarenal Cross-Clamping: an Experimental Study

Objective

Ischemia-reperfusion injury after acute ischemia treatment is a serious condition with high mortality and morbidity. Ischemia-reperfusion injury may result in organ failure particularly in kidney, lung, liver, and heart. In our study, we investigated the effects of papaverine and vitamin C on ischemia-reperfusion injury developed in the rat liver after occlusion-reperfusion of rat aorta.

Methods

32 Sprague-Dawley female rats were randomized into four groups (n=8). Ischemia was induced with infrarenal aortic cross-clamping for 60 minutes; then the clamp was removed and reperfusion was allowed for 120 minutes. While the control group and the ischemia-reperfusion group did not receive any supplementary agent, two other groups received vitamin C and papaverine hydrochloride (papaverine HCL). Liver tissues were evaluated under the light microscope. Histopathological examination was assessed by Suzuki's criteria and results were compared between groups.

Results

In ischemia-reperfusion group, severe congestion, severe cytoplasmic vacuolization, and parenchymal necrosis over 60% (score 4) were observed. In vitamin C group, mild congestion, mild cytoplasmic vacuolization and parenchymal necrosis below 30% (score 2) were found. In papaverine group, moderate congestion, moderate cytoplasmic vacuolization and parenchymal necrosis below 60% (score 3) were observed.

Conclusion

An ischemia of 60 minutes induced on lower extremities causes damaging effects on hepatic tissue. Vitamin C and papaverine are helpful in reducing liver injury after acute ischemia reperfusion and may partially avoid related negative conditions.

Prevention of post-traumatic clinical capillary leak syndrome

Systemic capillary leak is an early feature of the inflammatory response to localized injury, and is proportional to the severity of the inflammatory insult. Loss of local control of inflammation leads to an exaggerated systemic inflammatory response known as systemic inflammatory response syndrome (SIRS). SIRS is associated with multiple organ failure and death when there is failure to maintain homeostasis.

Whilst the application of molecular biology and recombinant techniques have produced major advances in our understanding of the mediation of the inflammatory response, there is no agent currently available which will prevent SIRS and reduce the incidence of post-traumatic multiple organ failure. In the meantime, a more practical approach to the avoidance of SIRS and its attendant capillary leak syndrome is to attempt to reduce the deleterious effects of interstitial oedema by tailoring treatment to the rapid changes in capillary permeability.

A randomized clinical trial of ascorbic acid in open abdominal aortic aneurysm repair

Background

Open AAA repair is associated with ischaemia-reperfusion injury where systemic inflammation and endothelial dysfunction can lead to multiple organ injury including acute lung injury. Oxidative stress plays a role that may be inhibited by ascorbic acid.

Methods

A double blind, allocation concealed, randomized placebo-controlled trial was performed to test the hypothesis that a single bolus dose (2g) of intra-operative parenteral ascorbic acid would attenuate biomarkers of ischaemia-reperfusion injury in patients undergoing elective open AAA repair.

Results

Thirty one patients completed the study; 18 received placebo and 13 ascorbic acid. Groups were comparable demographically. Open AAA repair caused an increase in urinary Albumin:Creatinine Ratio (ACR) as well as plasma IL-6 and IL-8. There was a decrease in exhaled breath pH and oxygenation. Lipid hydroperoxides were significantly higher in the ascorbic acid group following open AAA repair. There were no other differences between the ascorbic acid or placebo groups up to 4 hours after removal of the aortic clamping.

Conclusions

Open AAA repair caused an increase in markers of systemic endothelial damage and systemic inflammation. Administration of 2g parenteral ascorbic acid did not attenuate this response and with higher levels of lipid hydroperoxides post-operatively a pro-oxidant effect could not be excluded.

Trial registration

ISRCTN27369400

The utility of microalbuminuria measurements in pediatric burn injuries in critical care

PURPOSE

Microalbuminuria, as measured by urinary albumin-creatinine ratios (ACRs), has been shown to be a marker of systemic inflammation and an indicator of the potential severity of trauma and critical illness. Severe pediatric burns represent the best model in which to investigate the clinical utility of microalbuminuria. This study aims to ascertain whether ACR measurements have any role in predicting the severity or the intensive care requirements in the critically unwell pediatric burn population.

MATERIALS AND METHODS

A retrospective observational study was undertaken within a regional burn center with a dedicated 8-bed burn intensive care unit (ICU). This looked at 8 years of consecutive pediatric burns requiring intensive care support-a total of 63 patients after exclusions. Daily urinary ACR measurements were acquired from all patients.

RESULTS

All patients had greater than or equal to 1 ACR measurement out with the reference range, and only 8% (5/63) presented to the ICU with a normal ACR. The median day for the peak ACR measurement was day 4. The relative lack of mortalities (3/63) precluded adequate correlations between ACR and outcomes. Peak and mean ACR values correlate well with length of ICU stay, and the peak ACR also correlates with total length of hospital stay and severity of burn injury as measured by total body surface area burnt and number of organ systems requiring support. No significant differences were found when the patients were stratified by age. The peak ACR measurement was found to be independently predictive of the length of the ICU stay. As such, we have created a predictive model to prove that an ACR that remains less than 12 mg/mmol is predicative of an ICU stay of less than or equal to 7 days.

CONCLUSIONS

The clinical utilities of ACR measurements are demonstrated by their correlation with the severity of injury, length of ICU stay, and requirements for multiple organ support. Albumin-creatinine ratios raised over certain thresholds highlight to the clinician the need for closer observation and the potential deterioration of patients.

Prevalence, predictors and prognostic significance of microalbuminuria in acute cardiac patients: a single center experience

The objective of this study was to prospectively assess the prevalence, predictors and prognostic significance of microalbuminuria in a large cohort of consecutive acute cardiac patients, admitted to an intensive cardiac care unit from 1 January 2008 to 30 June 2009. In 815 acute cardiac patients, microalbuminuria is detectable in 39.3%. Microalbuminuria shows a significant negative correlation with left ventricular ejection fraction (Spearman's ρ = -0.228; p < 0.001), while it is positively correlated with C-reactive protein (Spearman's ρ = 0.239; p < 0.001), NT-pro-BNP (Spearman's ρ = 0.306; p < 0.001) and glycemia (Spearman's ρ = 0.191; p < 0.001). Microalbuminuria is an independent predictor for in-hospital mortality (1 μg/min step) (OR 1.015; 95% CI 1.008-1.023; p < 0.001). In the acute phase of cardiac patients, microalbuminuria is a common finding, and it represents an independent predictor for early mortality. It is strictly linked to the inflammatory activation (as indicated by C-reactive protein) and to acute glucose values, thus suggesting that it may be part of the acute response to stress.

Capillary leak syndrome in trauma: what is it and what are the consequences?

TICS is a complex disease that is clearly multifactorial in the traumatically injured patient (Fig. 2). Although systemic inflammation that occurs directly as a result of injury plays the most prominent role, the local tissue and organ injury effects of trauma not only cause local capillary leak and edema but also further amplify the SIRS response. High volume fluid administration and hypoproteinemic states further exacerbate the problem. All of this leads to organ dysfunction and failure, which is the third leading cause of death following injury. Strategies to treat TICS and attenuate its effects once it occurs by targeting inflammatory pathways have been wholly unsuccessful. The mainstay of therapy for TICS is prevention and minimization of its lethal effects. Newer resuscitation strategies such as hemostatic resuscitation and early goal-directed therapies are currently the best available strategies to combat TICS. Whether these result in better outcomes remains to be seen and the authors anxiously await the results of well-designed prospective trials.

Microalbuminuria in non-diabetic STEMI: an independent predictor for acute kidney injury

AIMS

To assess the impact of microalbuminuria on the development of acute kidney injury and to investigate its prognostic role at long term follow-up in 526 consecutive patients with ST elevation myocardial infarction without previously known diabetes.

METHODS

Microalbuminuria was measured using immunonephelemetry in the urine collected in the night.

RESULTS

Patients with microalbuminuria were older (p = 0.013). They showed higher values of peak glycemia (p = 0.017), peak Tn I (p < 0.001), NT-pro BNP (p = 0.020), ESR (p = 0.003), CRP (p = 0.020), and leukocyte count (p < 0.001). Lower eGFR was observed in patients with microalbuminuria both on admission and during ICCU stay (p = 0.048 and p = 0.003, respectively). A positive correlation was observed between CRP and microalbuminuria (Spearman's rho 0.114, p = 0.024). The composite end point was observed in 73 patients (18 patients died and 59 patients developed acute kidney injury). At multivariable regression analysis, microalbuminuria was an independent predictor of acute kidney injury. At follow-up [42.6 (25th-75th percentile, 17.5-56.8) months], Kaplan-Meier curve analysis showed that patients with microalbuminuria had a lower survival rate in respect to patients without microalbuminuria. Cox regression analysis documented that microalbuminuria was an independent predictor of long term mortality (HR: 1.089; 97% CI 1.036-1.145; p < 0.001).

CONCLUSIONS

In a large series of STEMI patients without previously known diabetes submitted to PCI, microalbuminuria, as a marker of endothelial permeability following higher systemic inflammatory activation and larger infarct lesions, is an independent predictor for the development acute kidney injury. Furthermore, microalbuminuria identifies a subset of patients at higher risk for long term mortality.

Endothelial glycocalyx dysfunction in disease: albuminuria and increased microvascular permeability

Appreciation of the glomerular microcirculation as a specialized microcirculatory bed, rather than as an entirely separate entity, affords important insights into both glomerular and systemic microvascular pathophysiology. In this review we compare regulation of permeability in systemic and glomerular microcirculations, focusing particularly on the role of the endothelial glycocalyx, and consider the implications for disease processes. The luminal surface of vascular endothelium throughout the body is covered with endothelial glycocalyx, comprising surface-anchored proteoglycans, supplemented with adsorbed soluble proteoglycans, glycosaminoglycans and plasma constituents. In both continuous and fenestrated microvessels, this endothelial glycocalyx provides resistance to the transcapillary escape of water and macromolecules, acting as an integral component of the multilayered barrier provided by the walls of these microvessels (ie acting in concert with clefts or fenestrae across endothelial cell layers, basement membranes and pericytes). Dysfunction of any of these capillary wall components, including the endothelial glycocalyx, can disrupt normal microvascular permeability. Because of its ubiquitous nature, damage to the endothelial glycocalyx alters the permeability of multiple capillary beds: in the glomerulus this is clinically apparent as albuminuria. Generalized damage to the endothelial glycocalyx can therefore manifest as both albuminuria and increased systemic microvascular permeability. This triad of altered endothelial glycocalyx, albuminuria and increased systemic microvascular permeability occurs in a number of important diseases, such as diabetes, with accumulating evidence for a similar phenomenon in ischaemia-reperfusion injury and infectious disease. The detection of albuminuria therefore has implications for the function of the microcirculation as a whole. The importance of the endothelial glycocalyx for other aspects of vascular function/dysfunction, such as mechanotransduction, leukocyte-endothelial interactions and the development of atherosclerosis, indicate that alterations in the endothelial glycocalyx may also be playing a role in the dysfunction of other organs observed in these disease states.

Microalbuminuria: A marker of systemic endothelial dysfunction during burn excision

INTRODUCTION

Systemic endothelial dysfunction characterises both burn injury and surgery and can be monitored by serial immunoassay of urine albumin (microalbuminuria). The aim of this study was to assess microalbuminuria before and during burn excision and identify factors that may influence it.

METHODS

Serial half-hourly urine albumin/creatinine ratio (ACR, normal <2.3mg/mmol) was measured in 25 adult patients during 44 burn-excision procedures, at a median of 5 days post-injury. Median total body surface area (TBSA) excised was 12%.

RESULTS

Pre-operative median ACR was normal rising to 3.25mg/mmol at 1.5h of surgery (p<0.05). Per-operative ACR at 0.5, 1, 2 and 2.5h were all associated with % TBSA burn excised (p<0.04). Median intraoperative ACR at 1h was 2.3mg/mmol for surgery within 48h post-injury, 1.6 for surgery at 2-7 days and 25.5 during excisions later than 1 month after injury (p<0.05). ACR at 1h was associated with CRP at 48h post-surgery (p=0.04). Per-operative ACR was also significantly correlated with post-operative complications.

CONCLUSION

Systemic endothelial dysfunction of acute thermal injury assessed by microalbuminuria recurs with surgery, is minimal at 2-7 days post-burn and affected by % TBSA burn excised and post-operative complications.

Microalbuminuria: A marker of endothelial dysfunction in thermal injury

INTRODUCTION

Systemic endothelial dysfunction (SED) and capillary leak occur following severe burn. SED can be assessed as low-level albuminuria (microalbuminuria) detectable only by sensitive immunoassay. This study compared the magnitude and duration of microalbuminuria with burn surface area and associated aggravating factors.

METHODS

Serial urine specimens were collected from 2 to 36 h after injury from 43 adult burn patients with a mean total body surface area (TBSA) of 32% (range 15-68%) and during 44 episodes of wound manipulation within the same period. Urinary albumin was expressed as the albumin/creatinine ratio (ACR, normal <2.3 mg/mmol).

RESULTS

Median ACR was highest 2h after injury (12.3 range 1.8-118 mg/mmol) returning to normal within 6 h. Full thickness burns (mean 17%) showed a significant association with ACR between 3 and 7h after burn. ACR was higher for up to 8 h in the presence of inhalation injury, alcohol intoxication or accelerant (p<0.05). ACR rose within 30 min of escharotomy or wound scrubbing (p<0.01).

CONCLUSION

Severe burn produces variable SED which recurs with wound manipulation. Inhalation injury, alcohol intoxication and accelerant all showed a stronger association with SED than TBSA. Microalbuminuria provides a means of monitoring microvascular integrity during the early after injury period.

Does N-Acetylcysteine Prevent Contrast-Induced Nephropathy During Endovascular AAA Repair? A Randomized Controlled Pilot Study

PURPOSE

To examine if N-acetylcysteine (NAC) reduces the incidence of contrast nephropathy during endovascular abdominal aortic aneurysm repair (EVAR) as evidenced by changes in markers of renal function.

METHODS

Twenty consecutive men (mean age 72 years, range 65-79) undergoing EVAR were randomized to receive standard intravenous fluid hydration or standard fluid hydration and NAC (600 mg BID orally, 4 doses). Venous blood and urine were collected prior to the procedure and for 5 postoperative days and analyzed blindly for serum creatinine, urinary retinol-binding protein (RBP), and albumin/creatinine ratio (ACR).

RESULTS

There were no significant differences in baseline demographics between the groups. No patient developed acute renal failure. In both groups, urinary RBP rose significantly from baseline (median 15 microg/mmol to peak 699 microg/mmol in controls versus 17 to 648 microg/mmol in the treatment group, p<0.003). There were similar significant rises in ACR (p<0.02). There was, however, no significant difference in the postoperative RBP or ACR between the groups at any time point.

CONCLUSION

EVAR causes significant acute renal injury in most patients. This was not attenuated by N-acetylcysteine. The causes of renal injury are probably multifactorial, the long-term clinical significance of which is unclear.

Low-dose hydrocortisone during severe sepsis: effects on microalbuminuria

OBJECTIVE

The aim of this study was to investigate the effect of low-dose hydrocortisone on glomerular permeability measured by the microalbuminuria to creatinine ratio (MACR) and on other markers of sepsis in severe septic patients.

DESIGN

Randomized prospective study.

SETTING

University intensive care unit.

PATIENTS

The study involved 40 patients with severe sepsis randomized into the hydrocortisone group (n = 20) and the standard therapy group (n = 20).

INTERVENTIONS

The hydrocortisone group received standard therapy plus a continuous infusion of hydrocortisone for 6 days, whereas the standard therapy group received only standard therapy.

MEASUREMENTS AND MAIN RESULTS

MACR, serum C-reactive protein, and procalcitonin concentrations were recorded every day from the day before the steroid therapy (T(0)) until the 6 days after (T(1), T(2), T(3), T(4), T(5), and T(6)). Concentrations in the hydrocortisone group and the standard therapy group were compared using Mann-Whitney test at each time. We also compared with Wilcoxon signed rank test the values determined in each group at T(0) with those at each subsequent time. Median MACR decreased from T(0) to T(6) in both patient groups; however, values were significantly lower in the hydrocortisone group from T(3) through to T(6). Median serum C-reactive protein also decreased from T(0) in both patient groups, with significantly lower values in the hydrocortisone group from T(3) through to T(6). There were no significant differences in procalcitonin between groups compared with baseline values or at any individual time point.

CONCLUSIONS

Low-dose hydrocortisone seems to reduce MACR and serum C-reactive protein but not procalcitonin in patients with severe sepsis. Further studies are needed to confirm these results and to understand the underlying molecular mechanisms.

Microalbuminuria in the intensive care unit: Clinical correlates and association with outcomes in 431 patients*

OBJECTIVE

Comparison of urine albumin within 6 hrs of intensive care unit (ICU) admission with demography, clinical classification, outcome, inotrope/vasopressor requirement, clinical assessment of mortality risk, and Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores.

DESIGN

Urine albumin-creatinine ratio (ACR) was measured on ICU admission (ACR 1) and after 4-6 hrs (ACR 2).

SETTING

A 17-bed general ICU in a university teaching hospital.

PATIENTS

Unselected medical (206) and surgical (225) patients recruited prospectively.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Bedside urine ACR was measured by nurses using a Bayer DCA 2000 analyzer and expressed in mg/mmol (reference range <2.3). ACR 1 in medical and surgical patients was 15.5 (12.4-19.5) and 8.2 (5.9-11.1) mg/mmol, respectively (p = .0002), and ACR 2 was 9.0 (5.8-12.5) and 4.6 (3.6-5.3), respectively (p < .0001). For all patients, median (95% confidence interval) ACR fell from 11.2 (8.7-13.2) to 5.4 (4.7-6.8) mg/mmol 4-6 hrs after ICU admission (p < .0001). ACR 1 for nonsurvivors (n = 90) and survivors (n = 341) was 16.1 (11.2-21.3) and 8.8 (6.9-11.9), respectively (p = .0002) and ACR 2, 12.4 (8.2-18.9) and 4.8 (3.9-5.4), respectively (p < .0001). In both medical and surgical patients who died on the ICU, median ACR failed to decrease significantly following admission. ACR1 and ACR 2 were higher in patients who required inotropic or vasopressor support and correlated with duration of therapy. ACR 1 and 2 were inversely correlated with mean Po2/Fio2 ratio 48 hrs after ICU admission and positively correlated with duration of mechanical ventilation and ACR 1 with ICU stay. ACR 2 predicted mortality and ACR 1 inotrope requirement independent of clinical mortality risk assessment and APACHE II and SOFA scores.

CONCLUSIONS

Urine albumin changes rapidly within the first 6 hrs following ICU admission and predicts ICU mortality and inotrope requirement as well as or better than APACHE II and SOFA scores. Serial urine albumin measurement may provide a means of monitoring the microvascular effects of systemic inflammation.

Urinary Albumin:Creatinine Ratio (ACR) and the Prediction of Postoperative Complications After Abdominal Aortic Aneurysm Repair

INTRODUCTION

Open repair of abdominal aortic aneurysm (AAA) requires aortic clamping. This results in an ischaemia-reperfusion injury (IRI) which can lead to the development of the systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF). We investigated the use of urinary albumin:creatinine ratio (ACR) as a simple predictor of the development of complications (SIRS) postoperatively.

METHODS

Forty-four patients undergoing elective infrarenal AAA repair and 10 control patients undergoing major abdominal surgery had fresh urine samples taken before, immediately after and 24 h after the procedure. Urinary ACR was calculated on all samples, and daily SIRS scores were calculated for all patients postoperatively. Systemic interleukin-6 (IL-6) levels were measured intraoperatively to measure the cytokine response to surgery.

RESULTS

AAA patients demonstrated a characteristic pattern of ACR levels during the three time points, with a significant increase in the ACR immediately postoperatively and with normalisation by 24 h (P<0.001 Wilcoxon signed ranks test). In comparison, control patients did not demonstrate any changes in their ACR (P=0.45 Wilcoxon signed ranks test) suggesting the increased ACR in AAA patients to occur as a result of IRI. ACR did not correlate with the development of SIRS postoperatively or with the systemic IL-6 response.

CONCLUSIONS

Infrarenal AAA repair is associated with a temporary and reversible renal injury. ACR could not, however, be used as a predictor of complications postoperatively.

Pulmonary and renal function following cardiopulmonary bypass is associated with systemic capillary leak

OBJECTIVE

The purpose of this study was to compare perioperative capillary permeability during cardiac surgery with subsequent pulmonary and renal function.

DESIGN

An observational prospective comparison of capillary permeability (microalbuminuria) during and after cardiopulmonary bypass (CPB), with postoperative pulmonary and renal function.

SETTING

A university teaching hospital.

PARTICIPANTS

Forty patients, mean (range) age 67.8 (50-85) years, undergoing elective first-time coronary artery bypass grafting (CABG).

INTERVENTIONS

Urine albumin concentration (AC) and albumin creatinine ratio (ACR) were compared with PO2 /FIO2 ratio, mechanical ventilation (intermittent positive-pressure ventilation [IPPV]) duration, and renal function.

MEASUREMENTS AND MAIN RESULTS

Median (range) AC and ACR increased from 8.3 (1.6-184.2) mg/L and 0.65 (0.1-18.8) mg/mmol preoperatively to 13.6 (1.6-267.2) mg/L and 4.80 (0.3-54.2) mg/mmol 10 minutes postbypass (p = 0.003 for ACR Wilcoxon rank test: not significant for AC). AC 2 hours postbypass was associated with mean PO2 /FIO2 ratio 0 to 2 hours postbypass and AC 4 hours postbypass was associated with mean PO2 /FIO2 ratio 0 to 2 and 2 to 12 hours postbypass (p < 0.05 Spearman). ACR 2 hours postbypass was associated with mean PO2 /FIO2 ratio 0 to 2 and 2 to 12 hours postbypass (p < 0.05 Spearman). AC 10 minutes and 2 hours postbypass and ACR 2 hours postbypass were associated with the duration of IPPV (p < 0.03). Day 1 serum creatinine was associated with pre- and 4 hours postbypass AC and ACR (p < 0.05). Day 2 serum creatinine was associated with 2 and 4 hours postbypass ACR (p < 0.05).

CONCLUSIONS

The magnitude of increase in capillary permeability during CABG is associated with later pulmonary and renal function.

The Effect of Acute Normovolaemic Haemodilution on the Inflammatory Response and Clinical Outcome in Abdominal Aortic Aneurysm Repair—Results of a Pilot Trial

OBJECTIVES

To determine the effect of acute normovolaemic haemodilution (ANH) on the inflammatory response and clinical outcome in elective open abdominal aortic aneurysm (AAA) repair.

DESIGN

Randomised controlled clinical trial.

METHODS

Thirty-six patients were randomised to undergo ANH or act as controls. Cell salvage was permitted in both groups. Heterologous blood was transfused according to pre-determined triggers. Outcome measures were markers of the systemic inflammatory response in serum and urine observed at multiple time points, and clinical recovery.

RESULTS

Median 890 (range 670-1620) ml of blood was removed at ANH in 16 patients. There were no differences in peri-operative changes in neutrophil count ( P = 0.13), serum C-reactive protein ( P = 0.38), interleukin-6 ( P = 0.50), total antioxidant capacity ( P = 0.73), urinary secretion of albumin ( P = 0.97) or retinol binding protein ( P = 0.41). There were no differences in the mortality and morbidity rates, systemic inflammatory response syndrome, ITU or hospital stay.

CONCLUSIONS

ANH, when used in combination with cell salvage, made no impact on systemic inflammatory response and clinical outcome when compared to cell salvage alone after AAA repair. ANH cannot be recommended for routine use in patients undergoing abdominal aortic aneurysm surgery when cell salvage is available.

Increased glomerular permeability and pulmonary dysfunction following major surgery: correlation of microalbuminuria and PaO/FiO ratio

BACKGROUND

The aim of our trial was to evaluate the ability of microalbuminuria as an indicator of outcome and to investigate its relationship with the postoperative respiratory dysfunction in the initial postoperative period in a high-risk patient group.

METHODS

In our prospective, observational study patients were consecutively recruited following elective oesophagectomy, total gastrectomy, Whipple-resection of the pancreas and liver resection due to tumour removal. Microalbuminuria (expressed as urine albumin:creatinine ratio, M:Cr) was measured before (tp), and after surgery (t0, t6, t24, t48, t72). Multiple Organ Dysfunction Scores were monitored on ICU admission than daily (t1, t2, t3). For statistical analysis, Wilcoxon's rank-sum test, Mann-Whitney's U-test, receiver operating characteristic curve analysis and Spearman's rho test were used as appropriate.

RESULTS

One hundred and forty patients (118 survivors and 22 non-survivors) were recruited. Significantly higher Multiple Organ Dysfunction Scores were observed in non-survivors throughout the study period (P < 0.001). Microalbuminuria (Cr) increased significantly (P < 0.01) on admission to the ICU (t0) compared with the preoperative levels, but levels returned to normal within 6 h and remained so for the rest of the study. There was a significant difference between survivors and non-survivors at t0 (P < 0.01). However the ROC curve indicated that M:Cr is not a reliable descriptor of outcome. Comparison of Cr values with the PaO2/FiO2 ratio showed an inverse relationship on admission, which remained so for t24 and t48.

CONCLUSION

M:Cr measured on admission to the ICU was significantly higher in non-survivors than in survivors, and also showed an inverse relationship with the PaO2/FiO2 ratio following extended abdominal surgery. However, on admission, M:Cr did not discriminate survivors from non-survivors. Further studies are required to evaluate the prognostic value of this test for postoperative patients with risk of respiratory failure.

Randomized study comparing the effects of hydroxyethyl starch solution with Gelofusine on pulmonary function in patients undergoing abdominal aortic aneurysm surgery

BACKGROUND

Restoring blood flow to ischaemic tissue can cause lung damage with pulmonary oedema. Hydroxyethyl starch (HES) solution, when used for volume replacement, may modify and reduce the degree of ischaemia-reperfusion injury. We compared the effects of HES solution with those of Gelofusine solution on pulmonary function, microvascular permeability and neutrophil activation in patients undergoing elective infrarenal abdominal aortic aneurysm surgery.

METHODS

Forty patients were randomized into two groups. The anaesthetic technique was standardized. Lung function was assessed with the PO(2)/FI(O(2)) ratio, respiratory compliance, chest x-ray and a score for lung injury. Microvascular permeability was determined by measuring microalbuminuria. Neutrophil activation was determined by measurement of plasma elastase.

RESULTS

Four hours after surgery, the median (quartile values) PO(2)/FI(O(2)) ratio was 40.3 (37.8, 53.1) kPa for the HES-treated patients compared with 33.9 (31.2, 40.9) kPa for the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The respiratory compliance was 80 (73.5, 80) ml cm(-1) H(2)O in the HES-treated patients compared with 60.1 (50.8, 73.3) ml cm(-1) H(2)O in the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The lung injury score 4 h after surgery was less for the patients treated with HES compared with the patients treated with Gelofusine (0.33 vs 0.71, P=0.01, Wilcoxon rank sum test). Mean (SD) plasma elastase was less in the HES-treated patients on the first postoperative day (1.96 (0.17) vs 2.08 (0.24), P<0.05). The log mean microalbuminuria was less in the HES-treated patients (0.41 vs 0.91 mg mmol(-1), P<0.05). This difference in microvascular permeability was associated with different volumes of colloid required to maintain stable cardiovascular measurements in the two groups of patients studied (3000 vs 3500 ml, P<0.01, Mann-Whitney test).

CONCLUSION

Compared with Gelofusine, the perioperative pulmonary function of patients treated with HES after abdominal aortic aneurysm surgery was better.

Salt of the earth or a drop in the ocean? A pathophysiological approach to fluid resuscitation

The evolved endocrine response after injury leads to sodium, chloride, and water retention at a time when large volumes of sodium containing fluids are given to maintain the circulation and preserve tissue oxygenation. Sodium, chloride, and water are also retained because of increased systemic vascular permeability to plasma proteins, especially albumin, which sequesters fluid in the interstitial space and causes oedema. Excessive fluid and electrolyte retention and interstitial oedema are associated with the systemic inflammatory response syndrome and multiple organ dysfunction, and failure. This review attempts an overview of these processes and addresses the question, "Can manipulation of fluid resuscitation influence the inflammatory response to injury and organ function". Results of randomised controlled prospective clinical studies suggest that limiting the sodium and chloride input and optimal use of synthetic colloids, which are well retained in the vascular space, can reduce the inflammatory response to injury and improve organ function.

Cytokine activation and intestinal mucosal and renal dysfunction are reduced in endovascular AAA repair compared to surgery

PURPOSE

To compare endovascular (EVR) to open repair (OR) of abdominal aortic aneurysm (AAA) for cytokine activation, changes in the intestinal mucosal barrier, and renal dysfunction.

METHODS

In a prospective nonrandomized study, 15 patients admitted to a university hospital for elective infrarenal AAA repair (8 OR and 7 EVR) were recruited. Intestinal permeability was assessed preoperatively (PO), at day 1 (D1), and at day 3 (D3) after surgery using the lactulose/mannitol differential excretion (LMR) test. Renal damage was assessed from measurements of the urinary albumin:creatinine ratio (ACR); cytokine activation was based on the urinary concentration of tumor necrosis factor receptor p55 (TNF-Rp55) at the same time points. Serum creatinine and urea concentrations were measured preoperatively and daily for 5 days postoperatively.

RESULTS

A significant increase in LMR was found in the OR group at D1 and D3 compared to PO (p<0.05). The LMR increase at D3 was significantly greater in the OR group (p<0.01). A significant difference was observed in the percentage rise in ACR on D1 in the OR group compared to the EVR group (p<0.005). The urinary TNF-Rp55 concentration was significantly elevated in the OR group at D1 (p<0.05) and D3 (p<0.05) compared to baseline; in the EVR group, it was elevated at D1 (p<0.05) compared to PO. The difference was also significant for this marker between the 2 groups at D1 (p<0.01). No significant change was observed in the serum creatinine or urea concentrations in either group perioperatively.

CONCLUSIONS

Endovascular AAA repair is associated with less cytokine production and less intestinal and renal dysfunction compared to the open approach.

CT of acute bowel ischemia

Bowel ischemia may be caused by many conditions and manifest with typical or atypical and specific or nonspecific clinical, laboratory, and radiologic findings. It may mimic various intestinal diseases and be confused with certain nonischemic conditions clinically and at computed tomography (CT). Bowel ischemia severity ranges from mild (generally transient superficial changes of intestinal mucosa) to more dangerous and potentially life-threatening transmural bowel wall necrosis. Causes of critically reduced blood flow to the bowel are diverse, ranging from occlusions of mesenteric arteries or veins to complicated bowel obstruction and overdistention. CT can demonstrate changes in ischemic bowel segments accurately, is often helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. Unfortunately, common CT findings in bowel ischemia are not specific, and specific findings are rather uncommon. Therefore, it often is a combination of nonspecific clinical, laboratory, and radiologic findings-especially detailed knowledge about the pathogenesis of acute bowel ischemia in different conditions-that helps most in correct interpretation of CT findings. To improve understanding of this complex heterogeneous entity, this article provides an overview of the anatomy and physiology of mesenteric perfusion and discussions of causes and pathogenesis of acute bowel ischemia, CT findings in various types of acute bowel ischemia, and potential pitfalls of CT.

Microalbuminuria and hyperthermia independently predict long-term mortality in acute ischemic stroke patients

OBJECTIVES

To investigate the association between microalbuminuria (MA) and hyperthermia in acute ischemic stroke and to evaluate their significance as the predictors of long-term mortality after stroke.

MATERIAL AND METHODS

We assessed neurologic deficit, urinary albumin excretion and body temperature in 60 patients admitted within 24 h after the onset of their first ischemic stroke. Outcome was assessed by 90-day and 1-year mortality.

RESULTS

MA was found in 46.7% of patients. Hyperthermia was found in 18.3% patients on Day 1 and in 25% patients on Day 2. The correlation between albuminuria on Day 2 and the body temperature on Days 1 and 2 was found (r = 0.45, and r = 0.30, respectively; both P < 0.05). The mortality was significantly higher in the group of patients with both MA and hyperthermia on Day 2 (73% vs 10% after 90 days; P < 0.0001 and 73% vs 18% after 1 year, P < 0.005). In the logistic regression analysis, albuminuria (P = 0.017), hyperthermia on Day 1 (P = 0.028) and neurologic deficit on admission (P = 0.044) independently predicted 1-year mortality after ischemic stroke.

CONCLUSION

Daily urinary albumin excretion correlates with the body temperature in acute stroke patients, but the predictive power of both these variables is independent of that association.

Mortality prediction at admission to intensive care: a comparison of microalbuminuria with acute physiology scores after 24 hours

OBJECTIVE

To compare low level albumin excretion (microalbuminuria), a marker of systemic capillary permeability, with mortality, Acute Physiologic And Chronic Health Evaluation (APACHE II) score, the Simplified Acute Physiologic (SAP II) score, and their derived mortality probabilities in patients admitted to a general intensive care unit.

DESIGN

Prospective observational study.

SETTING

A 14-bed intensive care unit in a university teaching hospital.

PATIENTS

A total of 140 consecutive patients (59 surgical, 48 medical, 22 trauma, and 11 burns).

INTERVENTIONS

Urine collection within 15 mins of intensive care unit admission for assessment of microalbuminuria.

MEASUREMENTS AND MAIN RESULTS

Microalbuminuria, expressed as the albumin-creatinine ratio (ACR: normal, <2.3 mg/mmol), was compared with mortality, APACHE II and SAP II scores and their derived mortality probabilities after 24 hrs, intensive care unit stay, and markers of organ function and inflammation. Median (95% confidence interval) ACR at admission for survivors (n = 115) and nonsurvivors (n = 25) were 4.2 (3.6-6.5) and 17.8 (8.0-40.8) mg/mmol, respectively (p =.0002 Mann Whitney). For 92 surgical, trauma, and burn patients, of whom 81 survived, ACR of >5.9 mg/mmol gave a sensitivity for death of 100%, specificity of 59%, positive predictive value of 25%, and negative predictive value of 100%. Mortality probability receiver operator characteristic curve areas for ACR, APACHE II, and SAP II were 0.843 (p <.0001), 0.793 (p =.0004), and 0.770 (p =.0017), respectively. ACR was associated with intensive care unit stay (p =.0021) and highest serum C-reactive protein (p =.0002), serum creatinine (p <.0001), and bilirubin (p =.0009). For 48 medical patients, of whom 34 survived, admission ACRs for survivors and nonsurvivors were 8.3 (5.7-10.8) and 10.7 (4.1-48.2) mg/mmol, respectively (p =.32). SAP II, but not APACHE II, score was significantly higher for nonsurvivors.

CONCLUSIONS

For surgical, trauma, and burn patients, but not medical patients, microalbuminuria within 15 mins of intensive care unit admission predicted death as well as APACHE II and SAP II scores calculated after 24 hrs, and it shows promise as a predictor of outcome.

A multiantioxidant supplementation reduces damage from ischaemia reperfusion in patients after lower torso ischaemia. A randomised trial

BACKGROUND

open repair of intra-abdominal aortic aneurysm (AAA) is associated with lower torso ischaemia and reperfusion.

OBJECTIVE

to examine the effect of antioxidants on the activation and sequestration of white blood cells and muscle injury during AAA repair.

METHOD

forty-two patients undergoing elective infrarenal aneurysm repair, were randomised to either standard therapy (22 patients) or standard therapy with additional multiantioxidant supplementation (20 patients). Vitamin E and C, Allopurinol, N-acetylcysteine and mannitol was administered perioperatively. White blood cell count (WBC), serum creatine kinase, aspartateaminotransferase, lactate and lipofuscine were measured.

RESULTS

WBC remained higher after reperfusion in the antioxidant group (p = 0.008). CK, ASAT and lipofuscine levels were significantly lower after reperfusion in the antioxidant group (p = 0.02, p = 0.018, p = 0.017).

CONCLUSION

multi-antioxidant supplementation was associated with a reduction in serum CK and ASAT after AAA repair. This is likely due to a reduction in oxidative stress and a decreased leucocyte sequestration and activation.

Renal tubular injury after infrarenal aortic aneurysm repair

OBJECTIVE

To investigate markers of tubular injury (glutathione-S-transferase [GST] isoforms) as early markers for renal damage in patients undergoing abdominal aortic aneurysm repair.

DESIGN

Prospective study.

SETTING

Regional teaching hospital.

PARTICIPANTS

Eight consecutive patients undergoing elective infrarenal abdominal aortic aneurysm repair.

INTERVENTIONS

All patients received a standard anesthetic technique including a dopamine infusion (3 microg/kg/min) but without supplemental renoprotective agents. Urine and blood samples were taken at induction, at 1 hour and 3 hours after limb reperfusion, and on days 1 and 2 postoperatively. Urine microalbumin and creatinine concentrations were measured using standard assays, and urine pi-GST and alpha-GST enzyme measurements were performed by a commercial immunoassay (Biotrin, Biotrin International Ltd., Co., Dublin, Ireland).

MEASUREMENTS AND MAIN RESULTS

Five patients (63%) showed a postoperative elevation of serum creatinine (median increase from baseline, 35.4%; range, 8.3% to 50.6%) that was associated with significant elevations of urinary microalbumin-to-creatinine, alpha-GST-to-creatinine, and pi-GST-to-creatinine ratios soon after clamp removal. The remaining 3 patients showed no increase in serum creatinine or urine proteins. Peak alpha-GST-to-creatinine levels were different between the 2 groups. The peak levels of GST enzymes were significantly (r(2) > 80%) associated with the percent increase in serum creatinine from baseline.

CONCLUSION

Urinary GST-to-creatinine ratios are a sensitive early biomarker for renal injury after infrarenal abdominal aortic aneurysm repair.

The gelatin-derived plasma substitute Gelofusine causes low-molecular-weight proteinuria by decreasing tubular protein reabsorption

PURPOSE

Proteinuria is frequently encountered in patients in the intensive care unit, most likely as a result of renal tubular cell injury. It has been reported that gelatin-derived plasma substitutes contribute to an increase in renal protein excretion. The aim of this study was to investigate the magnitude and the mechanism of the proteinuric effect of Gelofusine, a modified gelatin.

MATERIALS AND METHODS

In six healthy male subjects, renal hemodynamics and urinary protein excretion were measured before and after infusion of 330 mL of Gelofusine.

RESULTS

Gelofusine had a minor effect on blood pressure, glomerular filtration rate, effective renal plasma flow, and on urinary excretion of immunoglobulin, and albumin. In contrast, there was a major increase in the urinary excretion of the low-molecular-weight proteins beta2-microglobulin (from 0.06 +/- 0.04 to 43.52 +/- 11.75 microg/min; P <.01) and alpha1-microglobulin (from 11 +/- 8 to 72 +/- 24 microg/min; P <.01). The urinary excretion of N-acetyl-beta-D-glucosaminidase (beta-NAG) remained unchanged, suggesting that there was no significant renal tubular cell injury.

CONCLUSIONS

When analyzing proteinuria in patients in the intensive care unit it should be considered that Gelofusine increases the urinary excretion of proteins, in particular those of low molecular weight. This effect is most likely due to competitive inhibition of tubular protein reabsorption.

Differences in renal response between endovascular and open repair of abdominal aortic aneurysms

OBJECTIVES

to determine the difference in renal and systemic response between open and endovascular aneurysm repair.

MATERIALS AND METHODS

we studied prospectively 22 patients undergoing open repair (OR) and 15 patients undergoing endovascular repair (ER). Blood and urine samples were taken preoperatively (T0) and before clamping of the aorta or femoral artery (T1) and 5 min (T2), 1 h (T3), 6 h (T4), 24 h (Day 1) and 48 h (Day 2) after declamping. Albumin/creatinin ratio (AC ratio) in urine, serum albumin, serum creatinin, serum C-reactive protein and serum lactate were determined.

RESULTS

the urinary AC ratio in ER was significantly lower than in OR (p<0.001). In both groups the rise in urine albumin/creatinin ratio after declamping (T2, T3) was significant (p<0.001). C-reactive protein was raised significantly at day 1 and 2 in both groups (p<0.001) with no difference between the groups. Serum lactate values were significantly higher in OR. There was a significant increase in serum lactate 6 h after declamping in the ER group.

CONCLUSIONS

after endovascular repair renal damage is less compared to open repair. There is a significant systemic reaction to the endovascular repair causing mild, short-lasting damage to the kidney. This systemic response is most probably induced by a combination of ischaemia reperfusion injury and the surgical trauma of the procedure. Other possible explanations are discussed.

Endovascular AAA repair attenuates the inflammatory and renal responses associated with conventional surgery

PURPOSE

To quantify the inflammatory and renal parameters in comparative cohorts of patients undergoing surgical or endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

Forty-three patients (41 men; ages 58-81 years) underwent endovascular or conventional aneurysm surgery according to aortic morphology. All patients received a standard general anesthetic and had 12 serial blood and urine samples collected during the perioperative period. Samples underwent analysis for the cytokines interleukin (IL) 1beta tumor necrosis factor-alpha (TNF-alpha), and IL-6. White cell and platelet activation were estimated indirectly by measuring sL-selectin and 11-dehydrothromboxane B2, respectively. The urinary albumin:creatinine ratio (ACR) and N-acetyl-beta-D-glucosaminidase (NAG) activity were estimated to assess renal injury. Fibrinogen and fibrinogen degradation products were calculated to assess activation of the clotting cascade.

RESULTS

Twenty-three patients underwent endovascular AAA repair and 20 had conventional surgery. Concentrations of IL-6 (p < 0.002) and TNF-alpha (p < 0.0004) were significantly higher in the conventional group. The ACR (p < 0.002) and urinary NAGs (p < 0.0009) were also significantly higher in this group, suggesting greater renal injury. Platelet activity was significantly greater in the endovascular group (p < 0.01), perhaps indicating thrombus organization within the aneurysm sac.

CONCLUSIONS

These data suggest that the inflammatory response associated with conventional aneurysm repair is largely obviated by endovascular techniques. This may potentially translate to a lower incidence of multiple organ failure after endovascular surgery.

Randomized trial of hydroxyethyl starch versus gelatine for trauma resuscitation

BACKGROUND

Previous studies have demonstrated the rapid increase in systemic capillary permeability after blunt trauma and its association with poor outcome. There are theoretical advantages in resuscitation with colloid fluids, which are well retained in the vascular compartment during times of capillary leak. The aim of this study was to compare the effects of posttrauma resuscitation with hydroxyethyl starch (HES) (molecular mass, 250 kDa) or gelatine (molecular mass, 30 kDa), the hypothesis being that HES would reduce capillary leak.

METHODS

Forty-five patients suffering blunt trauma were randomized on admission to receive either gelatine (Gelofusine) (n = 21) or HES (Pentaspan) (n = 24) for the first 24 hours, after which the choice of fluid was at the discretion of the clinician. The mean Injury Severity Score for the HES and gelatine groups were 20.0 (range, 9-41) and 18.1 (range, 9-32), respectively (p = 0.43). Capillary permeability was assessed by urine albumin excretion rate for the first 24 hours. For 5 days the daily mean P(O2)/F(IO2) ratio, serum C-reactive protein, hemoglobin, white cell and platelet counts, prothrombin, and activated partial thromboplastin time were recorded.

RESULTS

Capillary permeability was lower in HES-treated patients during the first 24 hours. Log mean (95% confidence interval) albumin excretion rate for gelatine and HES groups at 6 hours were 117.5 (84.9) and 46.8 (24.3) microg/min (p = 0.011), at 12 hours were 54.9 (30.0) and 17.2 (7.6) microg/min (p = 0.001), and at 24 hours were 50.5 (23.4) and 23.6 (16.3) microg/min (p = 0.030), respectively. The mean (95% confidence interval) P(O2)/F(IO2) ratio for the HES and gelatine groups 48 hours after admission were 324 (44) and 267 (43) mm Hg, respectively (p = 0.03). The mean (95% confidence interval) serum C-reactive protein in the HES and gelatine groups 24 hours after admission were 72.4 (19.2) and 105.7 (30.1) mg/L, respectively (p = 0.03). There were no significant differences in any of the hematologic parameters during the first 48 hours.

CONCLUSION

The results suggest that compared with gelatine, resuscitation with HES reduces posttrauma capillary leak.

Biochemical and inflammatory changes in the exercising claudicant

Intermittent claudication is an early manifestation of atherosclerosis in the leg. The prognosis for the claudicating limb is reasonably good, but patients have excess cardiovascular morbidity and mortality rates compared with a control population. Increasing evidence suggests that the calf pain experienced when walking followed by rest generates a low-grade inflammatory response. The cumulative effects of these individual events may have an adverse effect on the progression of atherosclerosis. A review of the literature was performed to identify studies measuring the exercise-induced inflammatory response in claudicants and to try to identify the role of cumulative inflammatory changes in the progression of atherosclerosis. The effect of exercise training on these markers is briefly explored. Walking until the onset of calf pain (ischaemia) followed by rest (reperfusion) results in the generation of oxygen-derived free radicals, neutrophil activation and a generalized increase in vascular permeability. Baseline levels of chronic inflammatory markers such as acute-phase proteins are elevated in claudicants compared with controls, suggesting that the transient acute inflammatory response has longer-term consequences. Therapeutic exercise training appears to lead to an attenuation of these inflammatory markers. Intermittent claudication can be considered as part of an inflammatory disease process. However, the concerns that exercise training might potentiate the vascular inflammatory response appear to be unjustified, although further work is needed to clarify this. Exercise training should therefore be considered as an important treatment option for claudication.

von Willebrand factor and urinary albumin excretion are possible indicators of endothelial dysfunction in cardiopulmonary bypass

OBJECTIVE

Experimental evidence suggests that cardiopulmonary bypass (CPB) associated inflammatory response leads to endothelial injury and increased permeability, but this has been difficult to show clinically. We have investigated the use of von Willebrand factor (vWF), and urinary albumin excretion, as measured by the urinary albumin creatinine ratio (ACR), to demonstrate this.

METHODS

A total of 23 patients undergoing elective coronary artery bypass grafting were studied. Complement fragment C3a, leukotrienne B4 (LTB4), interleukin 6 (IL6), neutrophil elastase, vWF and ACR were measured on anaesthetic induction (baseline), 20 min after starting CPB, 5 min after cross-clamp removal, 5 min, 2, 6 and 24 h after termination of CPB. Anaesthetic, CPB and myocardial protection techniques were standardised. ANOVA was performed by using the distribution free Friedman test for each measured parameter. When significance differences were found (P < 0.05), post hoc analysis with Wilcoxon signed rank test was used for comparison of each time point with the base line level and differences were only accepted as significant following the Bonferroni correction (P < 0.008). Summary measures of peak versus peak and area under the cure were also analysed for ACR with vWF.

RESULTS

Peak vs. baseline levels for C3a were 4.9 vs. 2.1 microg/ml (P < 0.0001), LTB4 was 800 vs. 20 pg/ml (P < 0.0001), neutrophil elastase was 250 vs. 115 ng/ml (P < 0.001), IL6 was 620 vs. 1.4 pg/ml (P < 0.0001), vWF was 2.2 vs. 1.3 IU/ml (P < 0.0001) and ACR was 17.6 vs. 2.0 mg/mmol (P < 0.0001). C3a, LTB4 and ACR peaked during the operation. Neutrophil elastase peaked at 2 h following CPB. IL6 and vWF peaked at 6 h following CPB. The correlation coefficient between vWF and ACR following peak versus peak analysis was 0.48 (P = 0.035), and area under the curve analysis was 0.6 (P < 0.01).

CONCLUSION

These results demonstrate that endothelial permeability and injury, as measured by urinary albumin excretion and vWF, respectively, are related and the use of these easily detectable and sensitive biochemical markers warrants further investigation.

The evidence for exercise-induced inflammation in intermittent claudication: should we encourage patients to stop walking?

OBJECTIVES

To review clinical and experimental evidence that exercise to the onset of calf pain in patients with intermittent claudication results in an inflammatory response, and to consider whether repeated inflammatory events induced by therapeutic exercise training may lead to progression of atherosclerosis.

METHODS

A literature search was performed to identify studies measuring biochemical markers of exercise-induced ischaemia-reperfusion injury in patients with intermittent claudication. Current theories of atherogenesis were reviewed and the use of acute-phase proteins as potential markers of vascular disease explored.

RESULTS

Exercise to the onset of calf pain results in an inflammatory response with free radical formation, neutrophil activation and systemic vascular endothelial damage. Acute-phase proteins such as C-reactive protein and serum amyloid A protein have exciting potential use as stable biochemical markers of disease in claudication.

CONCLUSIONS

Further studies are needed to determine the effect of long-term exercise training on exercise-induced inflammation in claudication. Early work suggests, in fact, that exercise attenuates this inflammatory response. If this were confirmed then it would support the clinical impression that exercise training is beneficial in terms of symptomatic improvement and cardiovascular health in patients with intermittent claudication.

Prediction of posttraumatic adult respiratory distress syndrome by albumin excretion rate eight hours after admission

BACKGROUND

Adult respiratory distress syndrome (ARDS) in trauma victims carries a mortality on the order of 50%. An early feature is an increased capillary permeability causing an extravasation of plasma proteins and water, leading to interstitial edema. In the kidney, the increase in microvascular permeability is manifested as increased albumin excretion detectable by sensitive immunoassay.

METHODS

Forty seven trauma victims were studied for 5 days; 32 of them had Injury Severity Scores > 18. A diagnosis of ARDS was made on the recommendations of the American-European Consensus Conference on ARDS (1994). Eight patients developed ARDS, five developed pulmonary dysfunction, and the remainder showed no significant pulmonary abnormality.

RESULTS

Using the near patient urine albumin immunoassay, albumin excretion rate (AER) was measured after admission. For patients with Injury Severity Score > 18, the median (95% confidence interval) AER 8 hours after admission was 63 (range, 40-99) microg per minute for those without impaired lung function and 339 (range, 162-454) microg per minute for those in the combined ARDS and pulmonary dysfunction group (Mann-Whitney test, p = 0.0004). The median AER was 51 (range, 27-98) microg per minute for patients with Injury Severity Score < 18. The positive predictive value for the development of ARDS or pulmonary dysfunction of AER > 130 microg per minute was 85%, with a negative predictive value of 95%.

CONCLUSIONS

These data indicate that the capillary leak associated with the subsequent development of pulmonary dysfunction and ARDS can be detected within 8 hours of admission at the patient's bedside, thus providing a means of early identification of patients at greatest risk and allowing for early intervention.

Antioxidant depletion during aortic aneurysm repair

Ischaemia-reperfusion injury generates oxygen-derived free radicals leading to local and distant damage. A simple method of following oxidative activity is to measure the consumption of endogenous scavenging antioxidants; an enhanced chemiluminescent assay was used to study this phenomenon in 21 patients undergoing surgery for abdominal aortic aneurysm (AAA). Samples of peripheral venous blood were taken before induction of anaesthesia and then from a central venous line and the inferior mesenteric vein before, during, and after clamping of the aorta. Further specimens were taken from the central line at 2, 6 and 24 h after operation. Antioxidant concentration in the peripheral, central and inferior mesenteric blood were similar, indicating that anaesthesia and surgical dissection had no effect. Levels decreased significantly in central and inferior mesenteric blood during and after clamping, but returned to normal by 24 h. These results confirm ischaemia-reperfusion phenomena in AAA repair.