High-Dose Ascorbic Acid for Burn Shock Resuscitation May Not Improve Outcomes

American Burn Association Clinical Practice Guidelines on Burn Shock Resuscitation

This Clinical Practice Guideline (CPG) addresses the topic of acute fluid resuscitation during the first 48 hours following a burn injury for adults with burns ≥20% of the total body surface area (%TBSA). The listed authors formed an investigation panel and developed clinically relevant PICO (Population, Intervention, Comparator, Outcome) questions. A systematic literature search returned 5978 titles related to this topic and after 3 levels of screening, 24 studies met criteria to address the PICO questions and were critically reviewed. We recommend that clinicians consider the use of human albumin solution, especially in patients with larger burns, to lower resuscitation volumes and improve urine output. We recommend initiating resuscitation based on providing 2 mL/kg/% TBSA burn in order to reduce resuscitation fluid volumes. We recommend selective monitoring of intra-abdominal and intraocular pressure during burn shock resuscitation. We make a weak recommendation for clinicians to consider the use of computer decision support software to guide fluid titration and lower resuscitation fluid volumes. We do not recommend the use of transpulmonary thermodilution-derived variables to guide burn shock resuscitation. We are unable to make any recommendations on the use of high-dose vitamin C (ascorbic acid), fresh frozen plasma (FFP), early continuous renal replacement therapy, or vasopressors as adjuncts during acute burn shock resuscitation. Mortality is an important outcome in burn shock resuscitation, but it was not formally included as a PICO outcome because the available scientific literature is missing studies of sufficient population size and quality to allow us to confidently make recommendations related to the outcome of survival at this time.

Nutrition after severe burn injury

PURPOSE OF REVIEW

Severe burn injury causes significant metabolic changes and demands that make nutritional support particularly important. Feeding the severe burn patient is a real challenge in regard to the specific needs and the clinical constraints. This review aims to challenge the existing recommendations in the light of the few recently published data on nutritional support in burn patients.

RECENT FINDINGS

Some key macro- and micro-nutrients have been recently studied in severe burn patients. Repletion, complementation or supplementation of omega-3 fatty acids, vitamin C, vitamin D, antioxidant micronutrients may be promising from a physiologic perspective, but evidence of benefits on hard outcomes is still weak due to the studies' design. On the contrary, the anticipated positive effects of glutamine on the time to discharge, mortality and bacteremias have been disproved in the largest randomized controlled trial investigating glutamine supplementation in burns. An individualized approach in term of nutrients quantity and quality may proof highly valuable and needs to be validated in adequate trials. The combination of nutrition and physical exercises is another studied strategy that could improve muscle outcomes.

SUMMARY

Due to the low number of clinical trials focused on severe burn injury, most often including limited number of patients, developing new evidence-based guidelines is challenging. More high-quality trials are needed to improve the existing recommendations in the very next future.

An update of the effects of vitamins D and C in critical illness

Many critically ill patients are vitamin D and vitamin C deficient and the current international guidelines state that hypovitaminoses should be compensated. However, uncertainty about optimal dosage, timing and indication exists in clinical routine, mainly due to the conflicting evidence. This narrative review discusses both micronutrients with regards to pathophysiology, clinical evidence of benefits, potential risks, and guideline recommendations. Evidence generated from the most recent clinical trials are summarized and discussed. In addition, pragmatic tips for the application of these vitamins in the clinical routine are given. The supplementations of vitamin D and C represent cost-effective and simple interventions with excellent safety profiles. Regarding vitamin D, critically ill individuals require a loading dose to improve 25(OH)D levels within a few days, followed by a daily or weekly maintenance dose, usually higher doses than healthy individuals are needed. For vitamin C, dosages of 100-200 mg/d are recommended for patients receiving parenteral nutrition, but needs may be as high as 2-3 g/d in acutely ill patients.

Proceedings of the 2021 American Burn Association State and Future of Burn Science Meeting

Periodically, the American Burn Association (ABA) has convened a State of the Science meeting on various topics representing multiple disciplines within burn care and research. In 2021 at the request of the ABA President, meeting development was guided by the ABA's Burn Science Advisory Panel (BSAP) and a subgroup of meeting chairs. The goal of the meeting was to produce both an evaluation of the current literature and ongoing studies, and to produce a research agenda and/or define subject matter-relevant next steps to advance the field(s). Members of the BSAP defined the topics to be addressed and subsequently solicited for nominations of expert speakers and topic leaders from the ABA's Research Committee. Current background literature for each topic was compiled by the meeting chairs and the library then enhanced by the invited topic and breakout discussion leaders. The meeting was held in New Orleans, LA on November 2nd and 3rd and was formatted to allow for 12 different topics, each with two subtopics, to be addressed. Topic leaders provided a brief overview of each topic to approximately 100 attendees, followed by expert-lead breakout sessions for each topic that allowed for focused discussion among subject matter experts and interested participants. The breakout and topic group leaders worked with the participants to determine research needs and associated next steps including white papers, reviews and in some cases collaborative grant proposals. Here, summaries from each topic area will be presented to highlight the main foci of discussion and associated conclusions.

[Metabolomic changes of neonatal sepsis: an exploratory clinical study]

OBJECTIVES

To study the metabolic mechanism of neonatal sepsis at different stages by analyzing the metabolic pathways involving the serum metabolites with significant differences in neonates with sepsis at different time points after admission.

METHODS

A total of 20 neonates with sepsis who were hospitalized in the Department of Neonatology, Hunan Provincial People's Hospital, from January 1, 2019 to January 1, 2020 were enrolled as the sepsis group. Venous blood samples were collected on days 1, 4, and 7 after admission. Ten healthy neonates who underwent physical examination during the same period were enrolled as the control group. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used for the metabonomic analysis of serum samples to investigate the change in metabolomics in neonates with sepsis at different time points.

RESULTS

On day 1 after admission, the differentially expressed serum metabolites between the sepsis and control groups were mainly involved in the biosynthesis of terpenoid skeleton. For the sepsis group, the differentially expressed serum metabolites between days 1 and 4 after admission were mainly involved in pyruvate metabolism, and those between days 4 and 7 after admission were mainly involved in the metabolism of cysteine and methionine. The differentially expressed serum metabolites between days 1 and 7 after admission were mainly involved in ascorbic acid metabolism.

CONCLUSIONS

The metabolic mechanism of serum metabolites varies at different stages in neonates with sepsis and is mainly associated with terpenoid skeleton biosynthesis, pyruvate metabolism, cysteine/methionine metabolism, and ascorbic acid metabolism.

Burn Shock and Resuscitation: Review and State of the Science

Burn shock and acute fluid resuscitation continue to spark intense interest and debate among burn clinicians. Following a major burn injury, fluid resuscitation of burn shock is life-saving, but paradoxically can also be a source of increased morbidity and mortality because of the unintended consequence of systemic edema formation. Considerable research over the past two decades has been devoted to understanding the mechanisms of edema formation, and to develop strategies to curb resuscitation fluids and limit edema development. Recognition of burn endotheliopathy - injury to the endothelium's glycocalyx layer- is one of the most important recent developments in our understanding of burn shock pathophysiology. Newer monitoring approaches and resuscitation endpoints, along with alternative resuscitation strategies to crystalloids alone, such as administration of albumin, or plasma, or high dose ascorbic acid, have had mixed results in limiting fluid creep. Clear demonstration of improvements in outcomes with all of these approaches remains elusive. This comprehensive review article on burn shock and acute resuscitation accompanies the American Burn Association's State of the Science meeting held in New Orleans, LA on November 2-3, 2021 and the Proceedings of that conference published in this journal.

Different Depths May Not Determine the Fluid Resuscitation Volume in Early-stage Management of Severe Burns: a Model-Comparison Retrospective Analysis of Fluid Volume Determining Factors

BACKGROUND

Large-volume fluid resuscitation remains irreplaceable in the early-stage management of severe burns. We aimed to explore the relationship between fluid volume and other indicators.

METHOD

Data of severe burn patients with successful resuscitation in the early stage was collected. Correlation and linear regression analyses were performed. Multiple linear regression models, related goodness-of-fit assessment (adjusted R-square and Akaike Information Criterion), scatter plots and paired t-test for two models, and a likelihood ratio test were performed.

RESULTS

96 patients were included. The median of total burn area (TBA) was 70%TBSA, with full thickness burn area (FTBA)/TBA of 0.4, a resuscitation volume of 1.93 mL/kg/%TBSA. Among volume-correlated indicators, two linear regression models were established (Model 1: TBA × weight and tracheotomy; and Model 2: FTBA × weight, partial thickness burn area (PTBA) × weight, and tracheotomy). For these models, close values of Akaike Information Criterion, adjusted R-squares, outliers of the prediction range, and the result of paired t-test, all suggest similarity between two models estimations, while the likelihood ratio test for coefficients of FTBA × weight and PTBA × weight showed a statistical difference.

CONCLUSION

inhalational injury and decompression surgery only correlated with volume, while Tracheotomy, TBA × weight, FTBA × weight, and PTBA × weight correlated with and were accepted in linear models of volume. Although FTBA and PTBA differed statistically, there may be no need to distinguish them when estimating the resuscitation volume requirements in this patient set. Further study about different depths fluid should be conducted.

Vitamin C in Critically Ill Patients: An Updated Systematic Review and Meta-Analysis

Background: Vitamin C is a water-soluble antioxidant vitamin. Oxidative stress and its markers, along with inflammatory markers, are high during critical illness. Due to conflicting results of the published literature regarding the efficacy of vitamin C in critically ill patients, and especially the concerns for nephrotoxicity raised by some case reports, this meta-analysis was carried out to appraise the evidence and affirmation regarding the role of vitamin C in critically ill patients. Methods: We searched the database thoroughly to collect relevant studies that assessed intravenous vitamin C use in critically ill patients published until 25 February 2021. We included randomized controlled trials and observational studies with 20 or more critically ill patients who have received intravenous ascorbic acid (vitamin C). After screening 18,312 studies from different databases, 53 were included in our narrative synthesis, and 48 were included in the meta-analysis. We used the Covidence software for screening of the retrieved literature. Review Manager (RevMan) 5.4 was used for the pooling of data and Odds Ratios (OR) and Mean difference (MD) as measures of effects with a 95% confidence interval to assess for explanatory variables. Results: Pooling data from 33 studies for overall hospital mortality outcomes using a random-effect model showed a 19% reduction in odds of mortality among the vitamin C group (OR, 0.81; 95% CI, 0.66–0.98). Length of hospital stay (LOS), mortality at 28/30 days, ICU mortality, new-onset AKI and Renal Replacement Therapy (RRT) for AKI did not differ significantly across the two groups. Analysis of data from 30 studies reporting ICU stay disclosed 0.76 fewer ICU days in the vitamin C group than the placebo/standard of care (SOC) group (95% CI, −1.34 to −0.19). This significance for shortening ICU stay persisted even when considering RCTs only in the analysis (MD, −0.70; 95% CI, −1.39 to −0.02). Conclusion: Treatment of critically ill patients with intravenous vitamin C was relatively safe with no significant difference in adverse renal events and decreased in-hospital mortality. The use of vitamin C showed a significant reduction in the length of ICU stays in critically ill patients.

Effects of Micronutrients or Conditional Amino Acids on COVID-19-Related Outcomes: An Evidence Analysis Center Scoping Review

Recent narrative reviews have described the potential efficacy of providing individuals infected with coronavirus disease 2019 (COVID-19) with additional micronutrients to reduce disease severity. Although there are compelling reasons why providing additional micronutrients or conditional amino acids may affect COVID-19-related outcomes, evidence is lacking. The objective of this scoping review is to explore and describe the literature examining the effect of providing additional micronutrients or conditional amino acids (glutamine, arginine) in adults with conditions or infections similar to COVID-19 infection on COVID-19-related health outcomes. A literature search of the MEDLINE database and hand search of Cochrane Database of systematic reviews retrieved 1,423 unique studies, and 8 studies were included in this scoping review. Four studies examined a target population with ventilator-related pneumonia and acute respiratory distress syndrome, and the other 4 studies included patients who were at risk for ventilator-associated pneumonia. Interventions included intravenous ascorbic acid, intramuscular cholecalciferol, enteral and intramuscular vitamin E, enteral zinc sulfate, and oral and parenteral glutamine. In 6 of the 8 included studies, baseline status of the nutrient of interest was not reported and, thus, it is uncertain how outcomes may vary in the context of nutrient deficiency or insufficiency compared with sufficiency. In the absence of direct evidence examining efficacy of providing additional micronutrients or conditional amino acids to standard care, registered dietitian nutritionists must rely on clinical expertise and indirect evidence to guide medical nutrition therapy for patients infected with COVID-19.

High Dose Ascorbic Acid During Acute Resuscitation in Critically Burn Patients

Ascorbic acid (AA) is a potent oxygen-free radical scavenger. We hypothesized that treating severe burn patients with high doses of AA (HDAA) can reduce fluid resuscitation requirements and prevent organ dysfunction. We performed a unicentric, retrospective case-control study of 75 burn patients: 25 patients admitted from 2018 to 2019 with more than 30% Total Surface Body Surface Area (TSBA) burned who received HDAA (66 mg/kg/h as soon as possible after admission until 36 h after injury), and 50 patients admitted from 2014 to 2017 with similar Abbreviated Burn Severity Index (ABSI)/Baux scores who were treated with the same protocol but did not receive HDAA. During the first 24 hours of burn resuscitation the HDAA group required less fluids than the control group (3.06 ± 0.87 ml/kg/%TBSA vs 4.32 ± 1.51 P < .05), but the overall reduction of fluid requirements during the first 72 hours was not significant. There were no significant differences in Sequential Organ Failure Assessment (SOFA), other hemodynamic parameters, complications, or mortality. We also did not find an increase acute kidney injury in patients who received HDAA even though the mean urine oxalate/creatinine ratio was 0.61 (0.02-0.96). We conclude that in severe burn patients treated with a restrictive fluid therapy protocol, administration of HDAA can decrease only the initial fluid requirements but not total fluid intakes. We did not find differences in severity score after resuscitation or in mortality. Nor did we find an increase in renal failure in patients administered with HDAA.

Acute respiratory failure and burn patient outcomes

PURPOSE OF REVIEW

Advances in the care of inhalational injuries have not kept pace with advances that have been seen in the treatment of cutaneous burns. There is not yet a standard of care for best outcomes for airway management of patients with known or suspected inhalational injuries. Clinicians must decide if to intubate the patient, and if so, whether to intubate early or late in their presentation. Unnecessary intubation affects morbidity and mortality. This review will summarize literature that highlights present practices in the treatment of patients with inhalation injuries.

RECENT FINDINGS

There have been promising investigations into biomarkers that can be used to quantify a patient's risk and better target therapies. Grading systems serve to better stratify the burn victim's prognosis and then direct their care. Special ventilator modes can assist in ventilating burn patients with inhalation injuries that experience difficulties in oxygenating.

SUMMARY

Inhalational injuries are a significant source of morbidity and mortality in thermally injured patients. Treatment modalities, such as modified ventilator settings, alteration in fluid resuscitation, and a standardized grading system may improve morbidity and mortality.

Early Acute Kidney Injury Following Major Burns

Acute kidney injury (AKI) early after a major burn has not been widely studied. Our purpose was to evaluate the prevalence of and risk factors for early AKI and the effect of early AKI on outcome. Retrospective cohort study of adults with burns ≥20% TBSA admitted between November 24, 2015 and July 1, 2019. "Early AKI" occurring within 7 days of injury was identified using urine output and serum creatinine Kidney Disease International Global Outcome criteria. Multivariate regression models were developed for development of early AKI, development of AKI on day 0 or 1 postburn ("very early AKI"), and for in-hospital death. Among 85 patients, 62.4% developed early AKI, of which 26% had stage 3 AKI. Renal replacement therapy was required in 64% of stage 3 patients by day 7. Patients with early AKI were significantly older [50 (40.5-61) vs 37.5 (27.2-46.8) years, P < .001], and a significantly greater proportion was intubated in the first 24 hours postburn (90.6 vs 59.4%, P = .001). Resuscitation with high-dose vitamin C (HDVC) was independently associated with more frequent early AKI. Older age was significantly associated and HDVC was closely associated with increased very early AKI. In-hospital mortality was 37.7% for patients with early AKI. Older age, larger burn size, and development of early stage 3 AKI were independently associated with increased in-hospital death. Early AKI is common and carries a poor prognosis for survival. Resuscitation involving HDVC appears to be related to a higher likelihood of early and possibly very early AKI.

An Assessment of Research Priorities to Dampen the Pendulum Swing of Burn Resuscitation

On June 17 to 18, 2019, the American Burn Association, in conjunction with Underwriters Laboratories, convened a group of experts on burn resuscitation in Washington, DC. The goal of the meeting was to identify and discuss novel research and strategies to optimize the process of burn resuscitation. Patients who sustain a large thermal injury (involving >20% of the total body surface area [TBSA]) face a sequence of challenges, beginning with burn shock. Over the last century, research has helped elucidate much of the underlying pathophysiology of burn shock, which places multiple organ systems at risk of damage or dysfunction. These studies advanced the understanding of the need for fluids for resuscitation. The resultant practice of judicious and timely infusion of crystalloids has improved mortality after major thermal injury. However, much remains unclear about how to further improve and customize resuscitation practice to limit the morbidities associated with edema and volume overload. Herein, we review the history and pathophysiology of shock following thermal injury, and propose some of the priorities for resuscitation research. Recommendations include: studying the utility of alternative endpoints to resuscitation, reexamining plasma as a primary or adjunctive resuscitation fluid, and applying information about inflammation and endotheliopathy to target the underlying causes of burn shock. Undoubtedly, these future research efforts will require a concerted effort from the burn and research communities.

The use of vasopressors during acute burn resuscitation

BACKGROUND

Vasopressors may be required during acute burn resuscitation to support mean arterial blood pressure, but their use is not well-described in the burn literature. The purpose of this study was to examine vasopressor use during acute fluid resuscitation.

METHODS

Retrospective review of adults with burns ≥ 20% TBSA admitted to an ABA-verified regional burn center. Patients administered an infusion of a vasopressor for at least 30 min during the 1 st 48 h post-burn formed the PRESSOR group while patients who did not receive vasopressors formed the NoPRESSOR group.

RESULTS

We studied 52 burned adults, 85% of which had flame burns. Vasopressors were administered during resuscitation to 31% of patients. Vasopressor infusions began at 20.9 ± 10.9 h post burn and were continued for 16.8 ± 10.8 h. PRESSOR patients (N = 16) had significantly greater total (p = 0.001) and full thickness burn size (p < 0.001), and need for mechanical ventilation (p = 0.005) than NoPRESSOR patients (N = 36). PRESSOR and NoPRESSOR patients did not differ significantly in per cent predicted fluid volume received in the first 24 h (143 ± 58 Vs. 125 ± 46 respectively). PRESSOR patients compared to NoPRESSOR patients tended to have been administered 5% albumin (Alb) less often (38% Vs 47%) and high dose vitamin C (HDVC) more often during resuscitation (69% vs 17%). Multivariate regression analysis found that patient age (OR 1.189, 95% CI: 1.047, 1.351) and HDVC (OR 24.701, 95% CI: 1.558, 391.551) were independently associated with greater use of vasopressors. An inverse probability weighted propensity analysis also identified a significant association between HDVC and increased use of vasopressors (OR 6.902, 95 % CI: 2.503, 19.026), and significantly decreased vasopressor administration following Alb administration (OR 0.310, 95% CI: 0.130, 0.739).

CONCLUSION

Advanced age appears to be the most important determinant of vasopressor use during resuscitation. While vasopressor requirements appear to have been increased by HDVC and decreased by Alb, this needs to be formally evaluated in a large randomized study.

ABC's of Vitamin Supplementation in Critical Illness

Critical illness commonly presents as a systemic inflammatory process. Through this inflammation, there is an enhanced production of reactive oxygen and nitrogen species combined with marked reductions in protective plasma antioxidant concentrations. This imbalance is referred to as oxidative stress and is commonly encountered in numerous disease states in the critically ill including sepsis, trauma, acute respiratory distress syndrome, and burns. Oxidative stress can lead to cellular, tissue and organ damage as well as increased morbidity and mortality in critically ill patients. Supplementation with exogenous micronutrients to restore balance and antioxidant concentrations in critically ill patients has been considered for several decades. It is proposed that antioxidant vitamins, such as vitamins A and C, may minimize oxidative stress and improve clinical outcomes. Vitamin B formulations may play a role in curtailing lactic acidosis and are recently being evaluated as an acute phase reactant. However, few large, randomized trials specifically investigating the role of vitamin supplementation in the critically ill patient population are available. This article seeks to review recently published literature surrounding the role of supplementation of vitamins A, B and C in critically ill patients.

Initial management of severe burn injury

PURPOSE OF REVIEW

Patients with severe burn injuries pose significant challenges for the intensivist. Though average burn sizes have decreased over time, severe burn injuries involving greater than 20% of the total body surface area still occur. Verified burn centers are limited, making the management of severely burn injured patients at nonspecialized ICUs likely. Current practices in burn care have increased survivability even from massive burns. It is important for intensivists to be aware of the unique complications and therapeutic options in burn critical care management. This review critically discusses current practices and recently published data regarding the evaluation and management of severe burn injury.

RECENT FINDINGS

Burn patients have long, complex ICU stays with accompanying multiorgan dysfunction. Recent advances in burn intensive care have focused on acute respiratory distress syndrome from inhalation injury, acute kidney injury (AKI), and transfusion, resulting in new strategies for organ failure, including renal replacement therapy and extracorporeal life support.

SUMMARY

Initial evaluation and treatment of acute severe burn injury remains an ongoing area of study. This manuscript reviews current practices and considerations in the acute management of the severely burn injured patient.

Safety, Pharmacodynamics, and Efficacy of High- Versus Low-Dose Ascorbic Acid in Severely Burned Adults

In sepsis and burns, ascorbic acid (AA) is hypothesized advantageous during volume resuscitation. There is uncertainty regarding its safety and dosing. This study evaluated high dose AA (HDAA: 66 mg/kg/h for 24 hours) versus low dose AA (LDAA: 3.5 g/days) administration during the first 24 hours in severely burned adults. We conducted a retrospective study comparing fluid administration before and after switching from low dose to HDAA in severely burned adults. A total of 38 adults with burns >20% TBSA, who received either HDAA or LDAA were included in this retrospective study. AA serum concentrations were quantified at 0, 24, and 72 hours postburn. HDAA impact on hemodynamics, acid-base homeostasis, acute kidney injury, vasopressor use, resuscitation fluid requirement, urinary output, and the incidence of adverse effects was evaluated; secondary clinical outcomes were analyzed. AA plasma levels were 10-fold elevated in the LDAA and 150-fold elevated in the HDAA group at 24 hours and decreased in both groups afterwards. HDAA was not associated with a significantly increased risk of any complications. A significant reduction in colloid fluid requirements was noted (LDAA: 947 ± 1722 ml/24 hours vs HDAA: 278 ± 667 ml/24 hours, P = 0.029). Other hemodynamic and resuscitation measures, as well as secondary clinical outcomes were comparable between groups. HDAA was associated with higher AA levels and lower volumes of colloids in adults with severe burns. The rate of adverse events was not significantly higher in patients treated with HDAA. Future studies should consider prolonged administration of AA.

Influence of Vitamin C on Antioxidant Capacity of In Vitro Perfused Porcine Kidneys

Systemic and localized ischemia and reperfusion injury remain clinically relevant issues after organ transplantation and contribute to organ dysfunctions, among which acute kidney injury is one of the most common. An in vitro test-circuit for normothermic perfusion of porcine kidneys after warm ischemia was used to investigate the antioxidant properties of vitamin C during reperfusion. Vitamin C is known to enhance microcirculation, reduce endothelial permeability, prevent apoptosis, and reduce inflammatory reactions. Based on current evidence about the pleiotropic effects of vitamin C, we hypothesize that the antioxidant properties of vitamin C might provide organ-protection and improve the kidney graft function in this model of ischemia and reperfusion.

METHODS

10 porcine kidneys from 5 Landrace pigs were perfused in vitro for 6 h. For each experiment, both kidneys of one animal were perfused simultaneously with a 1:1 mixture of autologous blood and modified Ringer's solution at 38 °C and 75 mmHg continuous perfusion pressure. One kidney was treated with a 500 mg bolus injection of vitamin C into the perfusate, followed by continuous infusion of 60 mg/h vitamin C. In the control test circuit, an equal volume of Ringer's solution was administered as a placebo. Perfusate samples were withdrawn at distinct points in time during 6 h of perfusion for blood gas analyses as well as measurement of serum chemistry, oxidative stress and antioxidant capacity. Hemodynamic parameters and urine excretion were monitored continuously. Histological samples were analyzed to detect tubular- and glomerular-injury.

RESULTS

vitamin C administration to the perfusate significantly reduced oxidative stress (49.8 ± 16.2 vs. 118.6 ± 23.1 mV; p = 0.002) after 6 h perfusion, and increased the antioxidant capacity, leading to red blood cell protection and increased hemoglobin concentrations (5.1 ± 0.2 vs. 3.9 ± 0.6 g/dL; p = 0.02) in contrast to placebo treatment. Kidney function was not different between the groups (creatinine clearance vit C: 2.5 ± 2.1 vs. placebo: 0.5 ± 0.2 mL/min/100 g; p = 0.9). Hypernatremia (187.8 ± 4.7 vs. 176.4 ± 5.7 mmol/L; p = 0.03), and a lower, but not significant decreased fractional sodium excretion (7.9 ± 2 vs. 27.7 ± 15.3%; p = 0.2) were observed in the vitamin C group. Histological analysis did not show differences in tubular- and glomerular injury between the groups.

CONCLUSION

Vitamin C treatment increased the antioxidant capacity of in vitro perfused kidney grafts, reduced oxidative stress, preserved red blood cells as oxygen carrier in the perfusate, but did not improve clinically relevant parameters like kidney function or attenuate kidney damage. Nevertheless, due to its antioxidative properties vitamin C might be a beneficial supplement to clinical kidney graft perfusion protocols.

Effects of different ascorbic acid doses on the mortality of critically ill patients: a meta-analysis

BACKGROUND

Low levels of ascorbic acid (AA) have been detected in critically ill patients in which AA supplementation leads to promising outcomes. However, the ability of AA to reduce mortality in critically ill patients remains controversial. In this study, we have performed a meta-analysis to evaluate the effects of AA dose on the mortality of critically ill adults.

METHODS

Electronic databases were searched for trials in which AA had been intravenously administered to critically ill patients regardless of the dose or the co-administration of antioxidant agents. The predefined primary outcome included all-cause mortality at final follow-up.

RESULTS

The included trials enrolled a total of 1210 patients. Intravenous (IV) AA doses of 3-10 g/d reduced the mortality of critically ill patients (OR 0.25; 95% CI (0.14-0.46); p < 0.001; I2 = 0.0%), while low (< 3 g/d) and high AA doses (≥ 10 g/d) had no effect (OR 1.44; 95% CI (0.79-2.61); p = 0.234; I2 = 0.0% versus OR 1.12; 95% CI (0.62-2.03); p = 0.700; I2 = 0.0%). AA was associated with a decreased duration of vasopressor support and mechanical ventilation, but did not influence fluid requirement or urine output during the first 24 h of admission. The number of patients suffering from acute kidney injury and the length of intensive care unit or hospital stays were also unaffected by the AA.

CONCLUSION

Intravenous AA reduces the duration of vasopressor support and mechanical ventilation; 3-10 g AA results in lower overall mortality rates. Given the limitations of the primary literature, further studies are required to fully clarify the effectiveness of AA during the management of critically ill patients.