Microalbuminuria: A marker of endothelial dysfunction in thermal injury

Early Autocalibrated Arterial Waveform Analysis for the Management of Burn Shock-A Cohort Study

Adequate fluid therapy is crucial for resuscitation after major burns. To adapt this to individual patient demands, standard is adjustment of volume to laboratory parameters and values of enhanced hemodynamic monitoring. To implement calibrated parameters, patients must have reached the intensive care unit (ICU). The aim of this study was, to evaluate the use of an auto-calibrated enhanced hemodynamic monitoring device to improve fluid management before admission to ICU. We used PulsioflexProAqt® (Getinge) during initial treatment and burn shock resuscitation. Analysis was performed regarding time of measurement, volume management, organ dysfunction, and mortality. We conducted a monocentre, prospective cohort study of 20 severely burned patients, >20% total body surface area (TBSA), receiving monitoring immediately after admission. We compared to 57 patients, matched in terms of TBSA, age, sex, and existence of inhalation injury out of a retrospective control group, who received standard care. Hemodynamic measurement with autocalibrated monitoring started significantly earlier: 3.75(2.67-6.0) hours (h) after trauma in the study group versus 13.6(8.1-17.5) h in the control group (P < .001). Study group received less fluid after 6 h: 1.7(1.2-2.2) versus 2.3(1.6-2.8) ml/TBSA%/kg, P = .043 and 12 h: 3.0(2.5-4.0) versus 4.2(3.1-5.0) ml/TBSA%/kg, P = .047. Dosage of norepinephrine was higher after 18 h in the study group: 0.20(0.12-0.3) versus 0.08(0.02-0.18) µg/kg/min, P = .014. The study group showed no adult respiratory distress syndrome versus 21% in the control group, P = .031. There was no difference in other organ failures, organ replacement therapy, and mortality. The use of auto-calibrated enhanced hemodynamic monitoring is a fast and feasible way to guide early fluid therapy after burn trauma. It reduces the time to reach information about patient's volume capacity. Management of fluid application changed to a more restrictive fluid use in the early period of burn shock and led to a reduction of pulmonary complications.

Fluid Resuscitation and Cardiovascular Support in Acute Burn Care

Acute burn injury creates a complex and multifactorial local response which may have systemic sequelae such as hypovolemia, hypothermia, cardiovascular collapse, hypercoagulability, and multi-system organ failure. Understanding the underlying pathophysiology of burn shock, the initial burn triage and assessment, calculation of fluid requirements, and the means of tailoring ongoing interventions to optimize resuscitation are critical for overcoming the wide spectrum of derangements which this condition creates. As a result, this article discusses the various key points in order to garner a greater understanding of these nuances and the optimal pathway to take when tackling these challenging issues.

Long-Term Preservation of Renal Function in Septic Shock Burn Patients Requiring Renal Replacement Therapy for Acute Kidney Injury

BACKGROUND

The real impact of septic shock-associated acute kidney injury (AKI) on the long-term renal outcome is still debated, and little is known about AKI-burn patients. In a cohort of burn survivors treated by continuous renal replacement therapy (CRRT) and sorbent technology (CPFA-CRRT), we investigated the long-term outcome of glomerular and tubular function.

METHODS

Out of 211 burn patients undergoing CRRT from 2001 to 2017, 45 survived, 40 completed the clinical follow-up (cumulative observation period 4067 months, median 84 months, IR 44-173), and 30 were alive on 31 December 2020. Besides creatinine and urine albumin, in the 19 patients treated with CPFA-CRRT, we determined the normalized GFR by 99mTc-DTPA (NRI-GFR) and studied glomerular and tubular urine protein markers.

RESULTS

At the follow-up endpoint, the median plasma creatinine and urine albumin were 0.99 (0.72-1.19) and 0.0 mg/dL (0.0-0.0), respectively. NRI-GFR was 103.0 mL/min (93.4-115). Four patients were diabetic, and 22/30 presented at least one risk factor for chronic disease (hypertension, dyslipidemia, and overweight). Proteinuria decreased over time, from 0.47 g/day (0.42-0.52) at 6 months to 0.134 g/day (0.09-0.17) at follow-up endpoint. Proteinuria positively correlated with the peak of plasma creatinine (r 0.6953, p 0.006) and the number of CRRT days (r 0.5650, p 0.035) during AKI course, and negatively with NRI-GFR (r -0.5545, p 0.049). In seven patients, urine protein profile showed a significant increase of glomerular marker albumin and glomerular/tubular index.

CONCLUSIONS

Burn patients who experienced septic shock and AKI treated with CRRT had a long-term expectation of preserved renal function. However, these patients were more predisposed to microalbuminuria, diabetes, and the presence of risk factors for intercurrent comorbidities and chronic renal disease.

Electrolytes, albumin and acid base equilibrium during laparoscopic surgery

BACKGROUND

Surgery, causing inflammation, disrupts endothelial permeability leading to movement of fluids and albumin across the vascular barrier. Fluid therapy for restoring circulatory homeostasis may lead to positive fluid balance which has been shown to increase morbidity and mortality in surgical patients. The current investigation aims to describe physio-pathological changes in circulating albumin, fluid and electrolyte balance, and acidbase equilibrium in a cohort of patients undergoing laparoscopic surgery under general anesthesia.

METHODS

Single-center prospective observational study. Patients undergoing laparoscopic colorectal surgery were screened for eligibility.. Before surgery the baseline fasting conditions were homogenized. Hemoglobin, urinary and plasmatic were collected before surgery and then at pre-defined timepoints. Albumin/Creatinine ratio was measured before and after surgery. Expected and actual circulating Sodium concentrations were compared according to a physiological theoretical model. Assessment and quantification of changes in major electrolytes, albumin and acid-base balance was defined as the primary outcome of the study.

RESULTS

38 patients were enrolled in the protocol. Patients had a positive electrolytes (Na+ 295 [244-375] mmol, Cl- 234 [195-295] mmol, K+ 16.8 [12.0-21.4] mmol) and fluid balance (2165 [1727-2728] ml). The positive fluid balance was associated with stable chloride (105 [103-107], end study vs 103 [102-106] mmol/L, baseline, p=ns) and potassium (4.2 [3.8-4.4], end study vs 4.1 [3.6-4.4] mmol/L, baseline, p=ns) levels, but sodium concentrations decreased over time (138 [137-140], end study vs 139 [138-141] mmol/L, baseline, p<0.05). The Albumin/Creatinine ratio was higher at the end of surgery 134 [61-267] vs 7 [4-14], p<0.001).

CONCLUSIONS

Data from patients undergoing colorectal laparoscopic surgery showed a positive fluid balance, decreased circulating albumin and increased albuminuria. A positive sodium balance was not always associated with an increase in sodium plasma concentration.

Resuscitation with albumin using BET formula keeps at bay fluid administration in burned patients. An observational study

BET (Biological Engineering Technology) formula uses fluids with high albumin concentration to resuscitate burn patients. It estimates fluid resuscitation as a function of Body Burned Surface Area (BBSA) (ml/h = BBSA (m²) × 220) and administers it through a combination of lactated ringer and 20% Albumin starting at a 1:1 relationship. The proportion of albumin is decreased every 8 h, and infusion rate is modified according to urinary output. The study's purpose was to review resuscitation related variables of all burned patients treated in our unit using BET formula. We retrospectively analyzed all patients admitted to our critical care burn unit during a five year period. Only those admitted within the first 12 h post-burn injury were considered. 40 patients met all inclusion criteria. Resuscitation volume during the first 24 h was 2.58 ml/kg/%BBSA, significantly less than Parkland's estimation (4 ml/kg/%BBSA; P < 0.05). Patients were successfully resuscitated showing a significant base excess increase and lactate clearance during the resuscitation period (base excess 120%; lactate 29%; P < 0.05). Burn related complications where: ARDS 27%, renal dysfunction 53%, wound deepening 20%, abdominal compartment syndrome 4.5%. In conclusion, BET formula is capable of resuscitating burn patients successfully, limiting fluid administration.

Early Hemodynamic Management of Critically Ill Burn Patients

The challenge of initial hemodynamic resuscitation of severe burn patients is in avoiding under- and over-resuscitation associated with bad outcome. This review aims to propose strategies for the initial hemodynamic management of severe burns.

Supplemental Digital Content is available in the text.

The effect of fenofibrate on early retinal nerve fiber layer loss in type 2 diabetic patients: a case-control study

BACKGROUND

Previous studies suggested that use of fenofibrate could significantly reduce the rate of progression into diabetic retinopathy (DR), and that retinal nerve fiber layer (RNFL) loss, which has been considered an important indicator for retinal neurodegeneration, might precede microvascular changes. The aim of this study was to assess the effect(s) of fenofibrate on RNFL thickness at early stage of DR in patients with type 2 diabetes mellitus (DM).

METHODS

In this retrospective matched case-control study we included a cohort of 89 patients with type 2 DM, aged 40 or above, between Jan 1, 2017 and March 31, 2017. Among the subjects, 48 patients received fenofibrate therapy and the other 41 patients did not receive fenofibrate treatment. We defined use of fenofibrate as the presence of any prescription for fenofibrate within 1 year before or any time after the diagnosis of DM, and all the patients had either no DR or non-proliferative diabetic retinopathy (NPDR). The fibrate users were well matched with non-fenofibrate users for gender, age and axial length. The RNFL thickness in all quadrants of both eyes was examined with spectral domain optical coherence tomography (SD-OCT). The multiple linear regression analysis was used to assess the association of RNFL thickness with potential risk factors of DR other than fenofibrate use.

RESULTS

The non-fenofibrate users had significantly reduced RNFL thickness of the superior quadrant of the right eye compared to the fenofibrate users (t = 2.384, P = 0.019). On the contrary, BMI (p = 0.034) and ACR (p = 0.024) were both negatively correlated to the RNFL thickness of the right eye.

CONCLUSION

Oral administration of fenofibrate was suggestively associated with thicker RNFL in superior quadrant of the right eye of patents with early DR.

Vitamin D status and its influence on outcomes following major burn injury and critical illness

Vitamin D deficiency is common among the general population. It is also observed in up to 76% of critically ill patients. Despite the high prevalence of hypovitaminosis D in critical illness, vitamin D is often overlooked by medical staff as the clinical implications and consequences of vitamin D deficiency in acute contexts remain to be fully understood. Vitamin D has a broad range of pleotropic effects on various processes and systems including the immune-inflammatory response. 1α,25-dihydroxyvitamin D (1,25(OH)₂D), has been shown to promote a tolerogenic immune response limiting deleterious inflammatory effects, modulation of the innate immune system, and enhancement of anti-microbial peptides. Vitamin D deficiency is frequently observed in critically ill patients and has been related to extrinsic causes (i.e., limited sunlight exposure), magnitude of injury/illness, or the treatment started by medical doctors including fluid resuscitation. Low levels of vitamin D in critically ill patients have been associated with sepsis, organ failure, and mortality. Despite this, there are subpopulations of critical illness, such as burn patients, where the literature regarding vitamin D status and its influence on outcomes remain insufficient. Thermal injury results in damage to both burned and non-burned tissues, as well as induces an exaggerated and persistent immune-inflammatory and hypermetabolic response. In this review, we propose potential mechanisms in which burn injury affects the vitamin D status and summarizes current literature investigating the influence of vitamin D status on outcomes. In addition, we reviewed the literature and trials investigating vitamin D supplementation in critically ill patients and discuss the therapeutic potential of vitamin D supplementation in burn and critically ill patients. We also highlight current limitations of studies that have investigated vitamin D status and supplementation in critical illness. Thermal injury influences vitamin D status. More studies investigating vitamin D depletion in burn patients and its influence on prognosis, via standardized methodology, are required to reach definitive conclusions and influence clinical practice.

Albumin in Burn Shock Resuscitation: A Meta-Analysis of Controlled Clinical Studies

Critical appraisal of outcomes after burn shock resuscitation with albumin has previously been restricted to small relatively old randomized trials, some with high risk of bias. Extensive recent data from nonrandomized studies assessing the use of albumin can potentially reduce bias and add precision. The objective of this meta-analysis was to determine the effect of burn shock resuscitation with albumin on mortality and morbidity in adult patients. Randomized and nonrandomized controlled clinical studies evaluating mortality and morbidity in adult patients receiving albumin for burn shock resuscitation were identified by multiple methods, including computer database searches and examination of journal contents and reference lists. Extracted data were quantitatively combined by random-effects meta-analysis. Four randomized and four nonrandomized studies with 688 total adult patients were included. Treatment effects did not differ significantly between the included randomized and nonrandomized studies. Albumin infusion during the first 24 hours showed no significant overall effect on mortality. However, significant statistical heterogeneity was present, which could be abolished by excluding two studies at high risk of bias. After those exclusions, albumin infusion was associated with reduced mortality. The pooled odds ratio was 0.34 with a 95% confidence interval of 0.19 to 0.58 (P < .001). Albumin administration was also accompanied by decreased occurrence of compartment syndrome (pooled odds ratio, 0.19; 95% confidence interval, 0.07–0.50; P < .001). This meta-analysis suggests that albumin can improve outcomes of burn shock resuscitation. However, the scope and quality of current evidence are limited, and additional trials are needed.

Characterization of hypoalbuminemia following temporary abdominal closure

BACKGROUND

The purpose of this study was to characterize associations among serum proteins, negative-pressure wound therapy (NPWT) fluid loss, and primary fascial closure (PFC) following emergent laparotomy and temporary abdominal closure (TAC). We hypothesized that high levels of C-reactive protein (CRP) and NPWT output would be associated with hypoalbuminemia and failure to achieve PFC.

METHODS

We performed a retrospective analysis of 233 patients managed with NPWT TAC. Serum proteins and resuscitation indices were assessed on admission, initial laparotomy, and then at 48 hours, 96 hours, 7 days, and discharge. Correlations were assessed by Pearson coefficient. Multivariable regression was performed to identify predictors of PFC with cutoff values for continuous variables determined by Youden index.

RESULTS

Patients who failed to achieve PFC (n = 55) had significantly higher CRP at admission (249 vs. 148 mg/L, p = 0.003), initial laparotomy (237 vs. 154, p = 0.002), and discharge (124 vs. 72, p = 0.003), as well as significantly lower serum albumin at 7 days (2.3 vs. 2.5 g/dL, p = 0.028) and discharge (2.5 vs. 2.8, p = 0.004). Prealbumin (in milligrams per deciliter) was similar between groups at each time point. There was an inverse correlation between nadir serum albumin and total milliliters of NPWT output (r = -0.33, p < 0.001). Exogenous albumin administration (in grams per day) correlated with higher serum albumin levels at each time point: 48 hours: r = 0.26 (p = 0.002), 96 hours: r = 0.29 (p = 0.002), 7 days: r = 0.40 (p < 0.001). Albumin of less than 2.6 g/dL was an independent predictor of failure to achieve PFC (odds ratio, 2.59; 95% confidence interval, 1.02-6.61) in a multivariate model including abdominal sepsis, body mass index of greater than 40 kg/m, and CRP of greater than 250 mg/L.

CONCLUSIONS

Early and persistent systemic inflammation and high NPWT output were associated with hypoalbuminemia, which was an independent predictor of failure to achieve PFC. The utility of exogenous albumin following TAC requires further study.

LEVEL OF EVIDENCE

Prognostic study, level III; Therapeutic study, level IV.

Colloids in Acute Burn Resuscitation

Colloids have been used in varying capacities throughout the history of formula-based burn resuscitation. There is sound experimental evidence that demonstrates colloids' ability to improve intravascular colloid osmotic pressure, expand intravascular volume, reduce resuscitation requirements, and limit edema in unburned tissue following a major burn. Fresh frozen plasma appears to be a useful and effective immediate burn resuscitation fluid but its benefits must be weighed against its costs, and risks of viral transmission and acute lung injury. Albumin, in contrast, is less expensive and safer and has demonstrated ability to reduce resuscitation requirements and possibly limit edema-related morbidity.

Acute Fluid Management of Large Burns: Pathophysiology, Monitoring, and Resuscitation

This article reviews the pathophysiology of large burn injury and the extreme fluid shifts that occur in the hours and days after this event. The authors focus on acute fluid management, monitoring of hemodynamic status, and end points of resuscitation. Understanding the need and causes for fluid resuscitation after burn injury helps the clinician develop an effective plan to balance the competing goals of normalized tissue perfusion and limited tissue edema. Thoughtful, individualized treatment is the best answer and the most effective compromise.

In view of standardization Part 2: Management of challenges in the initial treatment of burn patients in Burn Centers in Germany, Austria and Switzerland

INTRODUCTION

Initial therapy of severe burns in specialized burn trauma centers is a challenging task faced by the treating multi-professional and interdisciplinary team. A lack of consistent operating procedures and varying structural conditions was recently demonstrated in preliminary data of our group. These results raised the question on how specific treatment measures in acute burn care are met in the absence of standardized guidelines.

MATERIAL AND METHODS

A specific questionnaire containing 57 multiple-choice questions was sent to all 22 major burn centers in Germany, Austria and Switzerland. The survey included standards of airway management and ventilation, fluid management and circulation, body temperature monitoring and management, topical burn wound treatment and a microbiological surveillance. Additionally, the distribution of standardized course systems was covered.

RESULTS

17 out of 22 questionnaires (77%) were returned completed. Regarding volume resuscitation, results showed a similar approach in estimating initial fluid while discrepancies persisted in the use of colloidal fluid and human albumin. Elective tracheostomy and the need for bronchoscopy with suspected inhalation injury were the most controversial issues revealed by the survey. Topical treatment of burned body surface also followed different principles regarding the use of synthetic epidermal skin substitutes or enzymatic wound debridement. Less discrepancy was found in basic diagnostic measures, body temperature management, estimation of the extent of burns and microbiological surveillance.

CONCLUSION

While many burn-related issues are clearly not questionable and managed in a similar way in most participating facilities, we were able to show that the most contentious issues in burn trauma management involve initial volume resuscitation, management of inhalation trauma and topical burn wound treatment. Further research is required to address these topics and evaluate a potential superiority of a regime in order to increase the level of evidence.

Fluid resuscitation management in patients with burns: update

Since 1968, when Baxter and Shires developed the Parkland formula, little progress has been made in the field of fluid therapy for burn resuscitation, despite advances in haemodynamic monitoring, establishment of the 'goal-directed therapy' concept, and the development of new colloid and crystalloid solutions. Burn patients receive a larger amount of fluids in the first hours than any other trauma patients. Initial resuscitation is based on crystalloids because of the increased capillary permeability occurring during the first 24 h. After that time, some colloids, but not all, are accepted. Since the emergence of the Pharmacovigilance Risk Assessment Committee alert from the European Medicines Agency concerning hydroxyethyl starches, solutions containing this component are not recommended for burns. But the question is: what do we really know about fluid resuscitation in burns? To provide an answer, we carried out a non-systematic review to clarify how to quantify the amount of fluids needed, what the current evidence says about the available solutions, and which solution is the most appropriate for burn patients based on the available knowledge.

Serum cystatin C and microalbuminuria in burn patients with acute kidney injury

BACKGROUND

This study was aimed at evaluating the effectiveness of serum cystatin C and microalbuminuria as diagnostic markers for acute kidney injury (AKI) in major burn patients.

MATERIALS AND METHODS

Major burn adult patients admitted to the burn intensive care unit within 24 h from the onset of injury were enrolled. Serum cystatin C and microalbuminuria (albumin-creatinine ratio, ACR) were obtained at postburn days 1, 3, 7, 14, 21 and 28. The patients were divided into two groups of the AKI group and the nonacute kidney injury group.

RESULTS

A total of 97 patients were enrolled in this study. Acute kidney injury was diagnosed in 40 patients (41.2%) at postburn day 17.3 ± 7.9. The area under the curve of the receiver operating characteristic curve for serum cystatin C was 0.808 (95% CI, 0.711-0.905, P < 0.001) at postburn day 7 and 0.908 (95% CI, 0.843-0.973, P < 0.001) at postburn day 14. The results were 0.610 (95% CI, 0.497-0.724, P = 0.069) for ACR at postburn day 7 and 0.694 (95% CI, 0.589-0.798, P = 0.001) at postburn day 14. The optimal cut-off value of serum cystatin C at postburn day 14 and ACR at postburn day 14 were 0.85 mg/L (sensitivity, 89.5%; specificity, 82.5%) and 41.51 mg/g cre (sensitivity, 60.5%; specificity, 61.4%), respectively. Serum cystatin C at postburn day 14 was the only significant factor in relation to AKI.

CONCLUSIONS

Serum cystatin C is a valuable diagnostic marker, whereas microalbuminuria is a relatively less significant marker for AKI in major burn patients.

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.

Neutrophil gelatinase associated lipocalin as an indicator of acute kidney injury and inflammation in burned children

INTRODUCTION

Neutrophil gelatinase associated lipocalin (NGAL) is a novel predictor of acute kidney injury (AKI), which increases with inflammation. We aimed to assess whether serum NGAL (SNGAL) and urine NGAL (UNGAL) can predict AKI in burned children.

METHODS

Patients were referred within the 12 h of burn to our center. Serum samples for SNGAL, C-reactive protein (CRP), procalcitonin (PCT) and urine for UNGAL, microalbumine (Umalb), creatinine (Ucr) were obtained at both admission and the 5th day after burn. Blood urea nitrogen (BUN) and serum creatinine (Scr) were examined daily.

RESULTS

Twenty-two subjects were enrolled and six (27.2%) of them developed AKI within the 48 h of injury. Burn size and abbreviated burn severity index (ABSI) were significantly increased in patients with AKI. CRP, PCT, SNGAL and UNGAL levels at admission and day 5 were significantly higher in patients with AKI than in those without AKI and controls. Scr was not significant between AKI and non-AKI groups at hospital days 1 and 5. A SNGAL level of 315 ng/ml and a UNGAL level of 100 ng/ml were determined as predictive cut-off values of AKI at admission (sensitivity and specificity: 71.4%, 83.3% and 93.3%, 93.7%, respectively). SNGAL and UNGAL were positively correlated with CRP, PCT, ABSI and Umalb/Ucr.

CONCLUSION

SNGAL and UNGAL are good early predictors of AKI in children with severe burn. NGAL might reflect the severity of burn insult and also could be used as an indicator of inflammation in burn children.

Unravelling the enigma of proteinuria in burn patients

Hu and coworkers in the previous issue of Critical Care provide evidence for the clinical relevance of proteinuria in the outcome of burn patients. Proteinuria is a common finding after severe burns, appears within a short period and is detectable for several weeks. Proteinuria ranging from 0.5 to 3 to 4 g/day is initially of mixed type, then, after a week, gradually changes to tubular proteinuria. The clinical role of proteinuria is still unclear, mainly due to a lack of data on its pathogenesis. Recent studies have demonstrated an association between proteinuria and incidence of inhalation injury, sepsis, acute kidney injury and mortality rate. Proteinuria is considered the mirror of increased systemic capillary permeability, and possibly a direct marker of glomerular and tubular injury. Circulating plasma inflammatory mediators and pro-apoptotic factors reflecting burn injury, sepsis and acute kidney injury can affect the viability and function of tubular cells and podocytes. These studies highlight that proteinuria in burn patients should receive due consideration.

Impaired endothelium-dependent vasodilatation is a novel predictor of mortality in intensive care

OBJECTIVE

Endothelial function may be impaired in critical illness. We hypothesized that impaired endothelium-dependent vasodilatation is a predictor of mortality in critically ill patients.

DESIGN

Prospective observational cohort study.

SETTING

Seventeen-bed adult intensive care unit in a tertiary referral university teaching hospital.

PATIENTS

Patients were recruited within 24 hrs of admission to the intensive care unit.

INTERVENTIONS

The SphygmoCor Mx system was used to derive the aortic augmentation index from radial artery pulse pressure waveforms. Endothelium-dependent vasodilatation was calculated as the change in augmentation index in response to an endothelium-dependent vasodilator (salbutamol).

MEASUREMENTS AND MAIN RESULTS

Demographics, severity of illness scores, and physiological parameters were collected. Statistically significant predictors of mortality identified using single regressor analysis were entered into a multiple logistic regression model. Receiver operator characteristic curves were generated. Ninety-four patients completed the study. There were 80 survivors and 14 nonsurvivors. The Simplified Acute Physiology Score II, the Sequential Organ Failure Assessment score, leukocyte count, and endothelium-dependent vasodilatation conferred an increased risk of mortality. In logistic regression analysis, endothelium-dependent vasodilatation was the only predictor of mortality with an adjusted odds ratio of 26.1 (95% confidence interval [CI], 4.3-159.5). An endothelium-dependent vasodilatation value of 0.5% or less predicted intensive care unit mortality with a sensitivity of 79% (CI, 59-88%) and specificity of 98% (CI, 94-99%).

CONCLUSIONS

In vivo bedside assessment of endothelium-dependent vasodilatation is an independent predictor of mortality in the critically ill. We have shown it to be superior to other validated severity of illness scores with high sensitivity and specificity.

Fluid management in major burn injuries

It is a widely accepted fact that severe fluid loss is the greatest problem faced following major burn injuries. Therefore, effective fluid resuscitation is one of the cornerstones of modern burn treatment. The aim of this article is to review the current approaches available for modern trends in fluid management for major burn patients. As these current approaches are based on various experiences all over the world, the knowledge is essential to improve the status of this patient group.

[Estimation of substitution volume after burn trauma. Systematic review of published formulae]

BACKGROUND

Fluid resuscitation after severe burns remains a challenging task particularly in the preclinical and early clinical phases. To facilitate volume substitution after burn trauma several formulae have been published and evaluated, nevertheless, the optimal formula has not yet been identified.

METHODS

A systematic PubMed search was performed to identify published formulae for fluid resuscitation after severe burns. The search terms "burn", "thermal", "treatment", "therapy" or "resuscitation", "fluid", "formula" and "adult", "pediatric" or "paediatric" were used in various combinations. Analysis was limited to the period from 01.01.1950 to 30.06.2010 and database entries in PubMed (http://www.pubmed.com). Additionally, references cited in the papers were analyzed and relevant publications were also included. Publications and formulae were assessed and classified by two independent investigators.

RESULTS

Within the specified time frame eight publications (five original contributions and three book chapters) were identified of which three formulae recommended colloid solutions, four recommended electrolyte solutions and one suggested hypertonic solutions within the first 24 h for fluid resuscitation. Only one formula specifically dealt with fluid resuscitation in infants.

CONCLUSION

The identified formulae led to sometimes strikingly diverse calculations of resuscitation fluid volumes. Therefore their use should be monitored closely and clinical values included. Urine output is a well established individual parameter. Use of colloid and hypertonic solutions leads to a reduced total fluid volume but is still controversially discussed.

Sepsis in burns: a review of current practice and future therapies

Sepsis is a major cause of death worldwide and remains the subject of much research and debate within the critical care community. Despite advances in burn prevention, treatment, and rehabilitation, sepsis remains a common cause of death in patients who have sustained a severe burn injury. The unique physical, metabolic, and physiologic changes seen after major thermal injury mean that the management of sepsis in burns poses a particular challenge and differs in many respects to the management of sepsis in the general critical care population. This article describes current issues in the prevention, diagnosis, and treatment of sepsis in burns with a review of the associated literature. In addition, we discuss possible future therapies for managing this condition.

Hydroxyethylstarch supplementation in burn resuscitation--a prospective randomised controlled trial

INTRODUCTION

Hydroxyethylstarches (HES) are thought to be beneficial in trauma and major surgery management, due to their volume expansion and anti-inflammatory properties. This study examined the use of 6% (HES) in burn resuscitation.

METHODS

26 adult patients with burns exceeding 15% total body surface area (TBSA) were randomised to either crystalloid (Hartmann's solution) or a colloid-supplemented resuscitation regime, where 1/3 of the crystalloid-predicted requirement was replaced by 6% HES.

RESULTS

There was no difference in age, gender or TBSA between the two groups. The median (95% CI) fluid volume/%TBSA received in the first 24 h was 307 ml and 263 ml for the crystalloid only and HES-supplemented group respectively (p=0.0234, Mann-Whitney). Body weight gain within the first 24 h after injury was significantly lower in the HES-supplemented group 2.5 kg versus 1.4 kg respectively (p=0.0039). The median (95% CI) serum C-reactive protein at 48 h after injury was 210 (167-257) and 128 (74-145) mg/L for the crystalloid only and HES-supplemented group respectively (p=0.0001). Albumin-creatinine ratio per % burn (ACR, a marker of capillary leak) was lower in the HES-supplemented group at 12h after burn (p=0.0310).

CONCLUSIONS

Patients treated with HES-supplemented resuscitation required less fluid, showed less interstitial oedema and a dampened inflammatory response compared to patients receiving isotonic crystalloid alone.

Loss of size selectivity of the glomerular filtration barrier in rats following laparotomy and muscle trauma

Posttraumatic microalbuminuria may be caused by either charge- or size-selective alterations in the glomerular filtration barrier, or both, and/or to a reduction in proximal tubular protein reabsorption. This study was performed to elucidate the pathophysiology of the increases in glomerular permeability occurring in rats exposed to a laparotomy or to a laparotomy and muscle trauma. In anesthetized Wistar rats (250-280 g), the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Rats were exposed to trauma by a laparotomy (L; n = 8), or by a combination of L and muscle trauma (MT; L+MT) induced by topical blunt injury of the abdominal muscles bilaterally. After L, muscles were crushed using hemostatic forceps at either 2 x 2 sites ("small" MT; n = 9), or at 2 x 5 sites ("large" MT; n = 9). Sham groups (n = 16), not exposed to a laparotomy, were used as controls. The glomerular sieving coefficients (theta) to polydisperse FITC-Ficoll-70/400 (molecular radius 13-80 A) were determined at 5 or 60 min after L and L+MT, respectively, from plasma and urine samples, and analyzed by high-performance size-exclusion chromatography. A tissue-uptake technique was used to assess theta for (125)I-labeled serum albumin. L, with or without MT, increased theta for Ficoll(55-80A) and albumin rapidly and markedly. Theta-Ficoll(70A) thus increased approximately threefold, and theta for albumin significantly, for all trauma groups. According to the "two-pore model" of glomerular permeability, these changes mainly reflect an increase in the number of large pores in the glomerular filter without any primary changes in the charge-selective properties of the filter.

Modern trends in fluid therapy for burns

The majority of burn centres use the crystalloid-based Parkland formula to guide fluid therapy, but patients actually receive far more fluid than the formula predicts. Resuscitation with large volumes of crystalloid has numerous adverse consequences, including worsening of burn oedema, conversion of superficial into deep burns, and compartment syndromes. Resuscitation fluids influence the inflammatory response to burns in different ways and it may be possible, therefore to affect this response using the appropriate fluid, at the appropriate time. Starches are effective volume expanders and early use of newer formulations may limit resuscitation requirements and burn oedema by reducing inflammation and capillary leak. Advanced endpoint monitoring may guide clinicians in when to 'turn off' aggressive fluid therapy and therefore avoid the problems of over-resuscitation.

Proteinuria without albuminuria: urinary protein excretion by a subset of patients with burn injuries

BACKGROUND

There is disagreement regarding the utility of urinary albumin excretion as a marker for capillary injury in patients with severe burn injuries. We examined protein components in urine specimens from patients with burn injury.

METHODS

Detailed analysis was performed for a set of 5 urine specimens selected based on a high ratio of albumin-sized molecules by size-exclusion HPLC (Accumin) versus albumin by immunoassay methods. Specimens were analyzed for total protein, alpha(1)-microglobulin, alpha(1)-acid glycoprotein, cystatin C, and retinol-binding protein. Urine components were analyzed by chromatographic and electrophoretic methods. Major components were identified by mass spectrometry of tryptic peptides.

RESULTS

A subset of urine specimens had increased total protein with slight increases in albumin by immunoassay or by polyacrylamide gel electrophoresis. Albumin values by size-exclusion HPLC were more than 10-fold higher. Immunoassays for alpha(1)-microglobulin and alpha(1)-acid glycoprotein yielded concentrations 5-10 fold higher than for albumin. Other major components identified included zinc-alpha(2)-glycoprotein and leucine-rich-alpha(2)-glycoprotein.

CONCLUSIONS

A subset of patients with burn injury had increased total urinary protein resulting primarily from increased excretion of proteins such as alpha(1)-microglobulin and alpha(1)-acid glycoprotein with little increase in albumin excretion. The unusual composition of urinary proteins in these patients may relate to decreased filtered load of albumin and increased filtered load of acute phase reactants or to alterations in renal tubular protein processing. Thus, measurement of urinary albumin may have decreased sensitivity for detecting kidney injury in burn patients.

Effects of early endotoxemia and dextran-induced anaphylaxis on the size selectivity of the glomerular filtration barrier in rats

This study was performed to investigate the glomerular permeability alterations responsible for the microalbuminuria occurring in endotoxemia and during anaphylactic shock. In anesthetized Wistar rats, the left ureter was catheterized for urine collection while, simultaneously, blood access was achieved. Endotoxemia was induced by lipopolysaccharide (LPS) from Escherichia coli, and glomerular permeability was assessed at 60 and 90 (n = 7) and 120 (n = 7) min. Anaphylaxis was induced by a bolus dose of Dextran-70, and glomerular permeability assessed at 5 min (n = 8) and 40 min (n = 9). Sham animals were followed for either 5 or 120 min. The glomerular sieving coefficients (theta) to fluorescein isothiocyanate-Ficoll (70/400) were determined from plasma and urine samples and assessed using size-exclusion chromatography (HPLC). After start of the LPS infusion (2 h), but not at 60 or 90 min, theta for Ficoll(70A) had increased markedly [from 2.91 x 10(-5) +/- 6.33 x 10(-6) to 7.78 x 10(-5) +/- 6.21 x 10(-6) (P < 0.001)]. In anaphylaxis, there was a large increase in theta for Ficolls >60 A in molecular radius already at 5 min, but the glomerular permeability was completely restored at 40 min. In conclusion, there was a transient, immediate increment of glomerular permeability in dextran-induced anaphylaxis, which was completely reversible within 40 min. By contrast, endotoxemia caused an increase in glomerular permeability that was manifest first after 2 h. In both cases, theta to large Ficoll molecules were markedly increased, reflecting an increase in the number of large pores in the glomerular filter.

Resonance scattering detection of trace microalbumin using immunonanogold probe as the catalyst of Fehling reagent-glucose reaction

A novel and sensitive resonance scattering (RS) spectral immunoassay for the determination of microalbumin (Malb) was developed, based on the catalytic effect of immunonanogold (ING) probe on Fehling reagent-glucose reaction, and resonance scattering effect of Cu(2)O particles. Nanogold particles in size of 10nm were used to label goat anti-human microalbumin (GMalb) to obtain an ING probe (AuGMalb) for Malb. The probe produced unspecific aggregation in pH 5.0 citric acid-Na(2)HPO(4) buffer solutions. Upon addition of Malb, the dispersed ING complex formed. The ING complex in supernatant was obtained by centrifuging and was used as catalyst for the reaction between Fehling reagent and glucose to form the Cu(2)O particles to amplify the resonance scattering signal at 610 nm. With addition of Malb, the ING complex in the supernatant increased and the RS intensity at 610 nm (I(610 nm)) enhanced linearly. The enhanced intensity DeltaI(610 nm) was proportional to the Malb concentration in the range of 0.014-0.43 ng ml(-1), with a detection limit of 7.2 pg ml(-1). The proposed method was applied to detect Malb in human urine sample with satisfactory results.

Microalbuminuria in acute burn injury

Microalbuminuria is a known finding in inflammatory states. We hypothesized that urinary albumin/creatinine ratio (ACR) would correlate with injury severity and resuscitation demands after acute burns. This pilot study evaluated 30 adults admitted within 12 hours of injury with burns > or =10% total body surface area burn injury (TBSA). The urinary ACR was calculated for each patient at 7 to 12 hours, 19 to 24 hours, and 43 to 48 hours following burn injury. Microalbuminuria was defined as a urinary ACR > or =20 mg/g. Study patients (23 males, 7 females) had a mean age of 42.9 + 14.0 years and a median TBSA burn injury of 18.8%. Inhalation injury was present in 10 of the study patients, and all patients with inhalation injury had microalbuminuria at the time of admission. One study patient died. Median time from burn injury to resuscitation was 30 hours, and the median fluid requirement was 4.2 ml/kg/%TBSA. Microalbuminuria was not uniformly present in burn-injured patients during the first 48 hours after injury. ACR values early in the hospital course correlated with higher lactate concentrations early after burn injury. However, ACR correlated with neither injury severity nor resuscitation demands after burn injury during any studied time range. Microalbuminuria does not have apparent clinical utility in burn-injured patients, and other markers of injury severity and resuscitation demands should be sought.

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.