[Initial shock from burns. Physiopathology: therapeutic principles]

Differential benefits of steroid therapies in adults following major burn injury

BACKGROUND

Major thermal injury induces a complex pathophysiological state characterized by burn shock and hypercatabolism. Steroids are used to modulate these post-injury responses. However, the effects of steroids on acute post-burn outcomes remain unclear.

METHODS

In this study of 52 thermally injured adult patients (median total burn surface area 42%, 33 males and 19 females), the effects of corticosteroid and oxandrolone on mortality, multi-organ failure (MOF), and sepsis were assessed individually. Clinical data were collected at days 1, 3, 7, and 14 post-injury.

RESULTS

Twenty-two (42%) and 34 (65%) burns patients received corticosteroids and oxandrolone within the same cohort, respectively. Following separate analysis for each steroid, corticosteroid use was associated with increased odds of in-hospital mortality (OR 3.25, 95% CI: 1.32-8•00), MOF (OR 2.36, 95% CI: 1.00-1.55), and sepsis (OR 5.95, 95% CI: 2.53-14.00). Days alive (HR 0.32, 95% CI: 0.18-0.60) and sepsis-free days (HR 0.54, 95% CI: 0.37-0.80) were lower among corticosteroid-treated patients. Oxandrolone use was associated with reduced odds of 28-day mortality (OR 0.11, 95% CI: 0.04-0.30), in-hospital mortality (OR 0.19, 95% CI: 0.08-0.43), and sepsis (OR 0.24, 95% CI: 0.08-0.69). Days alive, at 28 days (HR 6.42, 95% CI: 2.77-14.9) and in-hospital (HR 3.30, 95% CI: 1.93-5.63), were higher among the oxandrolone-treated group. However, oxandrolone was associated with increased MOF odds (OR 7.90, 95% CI: 2.89-21.60) and reduced MOF-free days (HR 0.23, 95% CI: 0.11-0.50).

CONCLUSION

Steroid therapies following major thermal injury may significantly affect patient prognosis. Oxandrolone was associated with better outcomes except for MOF. Adverse effects of corticosteroids and oxandrolone should be considered when managing burn patients.

Low-dose hydrocortisone reduces norepinephrine duration in severe burn patients: a randomized clinical trial

Introduction

The aim of this study was to assess the effect of low-dose corticosteroid therapy in reducing shock duration after severe burn.

Methods

A placebo-controlled, double-blind, randomized clinical trial (RCT) was performed on two parallel groups in the burn intensive care unit (ICU). Patients were randomized to receive either low-dose corticosteroid therapy or placebo for seven days. A corticotropin test was performed at the time of randomization, before the administration of the treatment dose. Thirty-two severely burned patients with refractory shock (>0.5 μg/kg/min of norepinephrine) were prospectively included in the study.

Results

We included 12 patients in the hydrocortisone-treated group and 15 patients in the placebo group in the final analysis. Among these patients, 21 were nonresponders to the corticotropin test. Median norepinephrine treatment duration (primary objective) was significantly lower in the corticosteroid-treated versus the placebo group (57 hours versus 120 hours, P = 0.035). The number of patients without norepinephrine 72 hours after inclusion was significantly lower in the treated group (P = 0.003, log-rank test analysis). The total quantities of norepinephrine administered to patients were lower in the hydrocortisone-treated versus the placebo group (1,205 μg/kg (1,079 to 2,167) versus 1,971 μg/kg (1,535 to 3,893), P = 0.067). There was no difference in terms of ICU or hospital length of stay, sepsis incidence, cicatrization or mortality.

Conclusions

In this placebo-controlled, randomized, double-blind clinical trial, we show for the first time that the administration of low-dose hydrocortisone in burn patients with severe shock reduces vasopressor administration.

Trial registration

Clinicaltrial.gov NCT00149123. Registered 6 September 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0740-0) contains supplementary material, which is available to authorized users.

Estrogen-provided cardiac protection following burn trauma is mediated through a reduction in mitochondria-derived DAMPs

Mitochondria-derived danger-associated molecular patterns (DAMPs) play important roles in sterile inflammation after acute injuries. This study was designed to test the hypothesis that 17β-estradiol protects the heart via suppressing myocardial mitochondrial DAMPs after burn injury using an animal model. Sprague-Dawley rats were given a third-degree scald burn comprising 40% total body surface area (TBSA). 17β-Estradiol, 0.5 mg/kg, or control vehicle was administered subcutaneously 15 min following burn. The heart was harvested 24 h postburn. Estradiol showed significant inhibition on the productivity of H2O2 and oxidation of lipid molecules in the mitochondria. Estradiol increased mitochondrial antioxidant defense via enhancing the activities and expression of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Estradiol also protected mitochondrial respiratory function and structural integrity. In parallel, estradiol remarkably decreased burn-induced release of mitochondrial cytochrome c and mitochondrial DNA (mtDNA) into cytoplasm. Further, estradiol inhibited myocardial apoptosis, shown by its suppression on DNA laddering and downregulation of caspase 1 and caspase 3. Estradiol's anti-inflammatory effect was demonstrated by reduction in systemic and cardiac cytokines (TNF-α, IL-1β, and IL-6), decrease in NF-κB activation, and attenuation of the expression of inflammasome component ASC in the heart of burned rats. Estradiol-provided cardiac protection was shown by reduction in myocardial injury marker troponin-I, amendment of heart morphology, and improvement of cardiac contractility after burn injury. Together, these data suggest that postburn administration of 17β-estradiol protects the heart via an effective control over the generation of mitochondrial DAMPs (mtROS, cytochrome c, and mtDNA) that incite cardiac apoptosis and inflammation.

Increasing percent burn is correlated with increasing inflammation in an adult rodent model

Burn injury has been associated with systemic/compartmental inflammatory responses and myocardial dysfunction. We hypothesized that burn size correlates with the extent of cardiac inflammatory response/contractile dysfunction. Adult male Sprague-Dawley rats were divided to receive anesthesia, a 3-degree burn covering 20%, 30%, 40%, or 60% total body surface area (TBSA) plus fluid resuscitation (lactated Ringer, 4 mL/kg per percent burn); sham burn animals were included as controls. There were seven rats in each group. Rats were euthanized Twenty-four h postburn, and TNF-alpha, IL-1beta, and IL-6 were measured in the plasma and in supernatant from isolated cardiac myocytes by enzyme-linked immunosorbent assay. In addition, left ventricular function (Langendorff) was studied in vitro, and troponin levels were measured by enzyme-linked immunosorbent assay. There were progressive, statistically significant increases in plasma and myocyte inflammatory cytokine levels, as well as plasma troponin with increasing burn size. Similarly, left ventricular pressure (in millimeters of mercury) and +/-dP/dtmax (in millimeters of mercury per second) progressively fell with increasing burn size. However, myocardial contractile depression induced by 60% TBSA burn was similar to that produced by 40% TBSA burn. These data suggest that the degree of inflammatory response, cardiac tissue injury, and myocardial contractile depression were correlated directly with the percent TBSA burn. However, unlike inflammation and cardiac tissue damage, myocardial contractile depression reached a plateau, with maximal myocardial contraction and relaxation defects observed at 40% TBSA burn, which were not further aggravated by a larger (60%) burn.

Cardiovascular distribution of the calcium sensing receptor before and after burns

Due to up-regulation of the parathyroid gland calcium-sensing receptor (CaR), burned children have hypocalcemic hypoparathyroidism, and decreased myocardial contractility. Our aim was to localize the CaR in the heart and measure receptor density changes due to burns. Heart and aorta samples from sheep subjected to 40% burn or sham conditions were probed for CaR via fluorescence microscopy. CaR was localized to endocardial endothelium, myocardial microvasculature, and fibroblasts and vessels of the aortic adventitia. CaR was not found in cardiomyocytes or smooth muscle cells. No differences in density of CaR or beta-adrenergic receptors were noted. No differences in CaR distribution were seen in the myocardium or aorta, in contrast to the parathyroid where burn injury up-regulates CaR. We suggest that CaR has a local, tissue-specific role, and functions in vascular calcium sensing for intravascular calcium deposition or regulation of other calcium channels after trauma or burn.

EFFECTS OF THE BRADYKININ B2 RECEPTOR ANTAGONIST ICATIBANT ON MICROVASCULAR PERMEABILITY AFTER THERMAL INJURY IN SHEEP

Peptide kinins are potent vasoactive agents in the microcirculation that might be released after burn injury. The present study was designed to test the hypothesis that Icatibant (JE 049), a potent, selective peptidomimetic bradykinin-B2 receptor antagonist, would reduce the cardiovascular pathology occurring in sheep exposed to 40% total body surface area (TBSA), third-degree burn. Female sheep were surgically prepared for chronic study. After 5 to 7 days' recovery from the operative procedure, they were randomized to five groups: sham (n = 6, noninjured, nontreated), medicated sham (n = 4, noninjured, treated with 20 microg kg h Icatibant), control (n = 7, 40% TBSA third-degree burn, nontreated), Icatibant-4 (n = 6, 40% TBSA third-degree burn, treated with 4 microg kg h Icatibant [low dose]), Icatibant-20 (n = 8, 40% TBSA third-degree burn, treated with 20 microg kg h Icatibant [high dose]). Prefemoral lymph flow (milliliters per hour) remained constant in the sham and medicated sham groups but increased after injury: control (0 h, 3.9 +/- 0.5; 24 h, 28 +/- 4.2; 48 h, 33.0 +/- 8.1). The increased fluid flux was associated with enhanced protein flux. Both low and high doses of Icatibant significantly reduced the microvascular fluid flux: Icatibant-4 (0 h, 5.3 +/- 0.6; 24 h, 17.5 +/- 3.5; 48 h, 20.3 +/- 3.4); Icatibant-20 (0 h, 5.3 +/- 1.1; 24 h, 15.2 +/- 2; 48 h, 17.6 +/- 4.1). Total prefemoral protein leak was reduced in all treatment groups. The low dose of Icatibant significantly reduced prefemoral lymph flow without adversely affecting the hemodynamic changes observed after burn injury in sheep, suggesting that the bradykinin antagonist would reduce edema formation and improve fluid management of thermally injured patients.

Beneficial effect of corticosteroids in catecholamine-dependent septic burn patients

Recent studies indicated the benefit of hydrocortisone in septic patients based on the significant reduction of catecholamines and improved outcome in common intensive care patients. The treatment of intensive care burn patients with corticosteroids was discussed with great caution due to the especially compromised immune status of severely burned patients. The purpose of this study was to investigate the influence of corticosteroids in burn patients during septic shock. In our burn unit, we started with the administration of cortisol in 2001. In this retrospective study, 10 severely burned patients received, > or = 24h after norepinephrine dependency, hydrocortisone infusions of 200 mg/24 h. The course of norepinephrine dose, hemodynamic measurements (Swan-Ganz-Catheter) and daily Sequential Organ Failure Assessment (SOFA-Score) were analyzed and compared to nine (catecholamine-dependent) burn patients without cortisol therapy. Statistical analysis by means of Fisher's Exact Test revealed beneficial effects (morbidity and mortality) of low dose cortisol therapy compared to control patients. However, the results of this study must be interpreted with caution because of its limited number of patients and its retrospective character. Further randomized prospective controlled studies are necessary to determine the efficacy and safety of cortisol therapy in burn patients.

[Unusual haemostasis disorder in a seriously burned patient]

We report the case of a woman severely burned during a gas explosion with an unusual disorder of haemostasis. The prothrombin time was very elevated, essentially by a drop in factor II. This abnormality persisted for a long time after the correction of the dilutional and consumption coagulopathy which followed immediately the burn. Blood analysis found fluindione and benzodiazepine derivatives. Such a disorder during a potentially suicidal burn must evoke a toxic aetiology.

Hydrocortisone improved haemodynamics and fluid requirement in surviving but not non-surviving of severely burned patients

Recent studies have shown that administration of hydrocortisone may lead to a reduction of catecholamines and to an improved outcome in septic patients. However, there are no data on the use of hydrocortisone in burn patients although in these patients reduction of vasopressors might be even more crucial for outcome due to improvement of skin perfusion. This study presents the first results on the impact of hydrocortisone administration in norepinephrine dependent severely burned patients. In a prospective cohort study fourteen consecutive severely burned patients received, 12h after norepinephrine dependency, a hydrocortisone bolus of 100mg followed by 0.18mg/(kgh) hydrocortisone. The course of the necessary norepinephrine dose, as well as the fluid balance was documented 12h prior and after the first dosage of hydrocortisone. Statistical analysis showed an unexpected increase of the required norepinephrine dosage. A statistical post hoc evaluation of surviving and non-surviving patients revealed a significant increase of norepinephrine in non-survivors whereas in survivors it was possible to reduce norepinephrine significantly. Furthermore, the median fluid requirement of surviving patients could be significantly reduced whereas in the group of non-survivors there was no change of volume needed. Our data suggests that hydrocortisone might be useful in selected patients with severe burn injuries. However, patients not responding to hydrocortisone administrations seem to have a poor prognosis. Our findings are in contrast to previously published data on septic patients, in whom hydrocortisone administration resulted in a reduction of norepinephrine. In burned patients the severity of trauma seems to have more profound influence on the pathophysiological mechanism of sepsis. Due to the high number of non-responders, the potential immune suppression and impaired wound healing caused by the side effects of hydrocortisone, further selection criteria seem to be necessary. A short ACTH-test might be considered prior to hydrocortisone administration to select patients who might benefit from this therapy. In summary, further prospective controlled studies will be necessary to establish hydrocortisone in the routine therapy of severely burned patients.