Microangiography: An alternative Tool for Assessing Severe Frostbite Injury. Lacey AM, Fey RM, Gayken JR, Endorf FW, Schmitz KR, Punjabi GV, Masters TC, Nygaard RM. J Burn Care Res. 2019 Aug 14; 40(5):566-569.
Frostbite is a cold injury that has the potential to cause considerable morbidity and long-term disability. Despite the complexity of these patients, diagnostic and treatment practices lack standardization. This article evaluates the use of microangiography (MA) as a modality for “low tech”, rapid diagnosis of severity of frostbite injury as an alternative to more resource intensive modalities such as Technetium 99 (Tc99) bone scans and catheter directed angiography. MA is an imaging modality that uses peripherally injected indocyanine green (IcG) and ultraviolet light to assess perfusion in the vasculature of soft tissue. The authors performed a single center, retrospective review of patients diagnosed with severe frostbite injury from the years 2006 -2018. 82 patients had Tc99 bone scan only, 22 patients who received MA alone, and 26 who received both modalities (MA + Tc99). Importantly, all patients underwent these studies AFTER intravenous thrombolytic therapy with alteplase. The authors found that Tc99 and MA had strong correlation with eventual amputation level (r=.836, P<.001; r=.870, P< .001, respectively). MA, however, was found to have a significantly stronger correlation with perfusion deficit scores (r=.890, P<.001) compared to Tc99 which demonstrated a moderate correlation (r=.525, P<.006) with the perfusion deficit score (A “tissue at risk” scoring worksheet developed at the authors institution; Hennepin Frostbite Score).
The authors successfully argue that MA provides a safe and accurate method for predicting final amputation level. These studies could be performed with minimal specialized equipment or staff and be used upfront to diagnose extent of tissue compromise on admission as well as evaluate response to therapy. Given that this was a retrospective study that only used MA after treatment, there will need to be future studies to validate MA. However, MA has great potential to be utilized in lower resource settings or where Tc99 and angiography are delayed or unavailable.
Effect of High dose vitamin C therapy on severe burn patients: a nationwide cohort study. Nakajima M, Kojiro M, Aso S, Matsui H, Fushimi K, Kaita Y, Goto H, Yamaguchi Y, Yasunaga H. Crit Care. 2019 Dec 12; 23(1):407.
High dose vitamin C infusions have been used as an adjunct in burn resuscitations for the past few decades. As an anti-oxidant, the agent is thought to attenuate vascular permeability by counteracting the effects of oxidative stress in high doses. Despite the mechanistic evidence for vitamin C as a resuscitation adjunct in burns, no previous study has shown a mortality benefit. Several small prospective series have demonstrated decreased fluid resuscitation volumes at 24 hours and reduced edema, but no clear mortality or morbidity improvements. Additionally, there is currently no standard dosage that constitutes “high dose”.
The authors of this article attempt to elucidate the effects of two different dosage levels of vitamin C infusion (10g or 24g in 48 hours) during burn resuscitation against a propensity matched control cohort (No vitamin C infusion). They conducted a nationwide, retrospective cohort study utilizing a Japanese national database. The control cohort patients were propensity matched in a 4:1 ratio. The median 48 hour dose given was 50grams for the treatment cohort. The authors found an in-hospital mortality benefit for the 10g threshold dose when compared to propensity matched controls (risk ratio, 0.79; 95% confidence interval, 0.66-0.95). The 24g threshold did not show a mortality improvement. Interestingly, the high dose vitamin C group (10g threshold) showed statistically higher 24h, 72h and 7 day fluid requirements when compared to controls. The 24g threshold had similar fluid volumes to the control group.
The results of this study will not quell the controversy over Vitamin C infusion in burn resuscitation; however, this is the first study to show a potential survival benefit. While there are many confounding factors, consideration of this therapy remains warranted. This is the largest cohort studied in this manner and indicates that we need future large prospective studies to answer many of these questions.