Laser Doppler monitoring of microcirculatory changes in acute burn wounds

Because burns are dynamic wounds that can change in apparent depth during the first 72 hours, we asked whether measuring changes in cutaneous blood flow might help predict the ultimate fate of burns that were not obviously shallow or deep. A laser Doppler flowmeter was used to study cutaneous perfusion for at least 72 hours in partial-thickness wounds on patients with burns of less than 15% TBSA and in experimental wounds of similar size on rats. Clinical wounds that healed without grafting consistently showed elevated perfusion levels which increased further within 72 hours, whereas wounds eventually requiring grafting experienced lower perfusion levels with no obvious pattern of increase. Differences between average flow levels for healing and nonhealing burns were statistically significant throughout the study period. Perfusion levels in experimental wounds were stratified according to burn severity, with shallower wounds showing a pattern of increase similar to the clinical wounds.     

Noncontact laser Doppler imaging in burn depth analysis of the extremities

The purpose of this study was to determine the accuracy and practical utility of a noncontact laser Doppler imager (PIM-II, Lisca Development AB, Link?ping, Sweden) in the estimation of burn depth in the upper and lower extremities. At 48 hours after burn injury, we performed scans of 35 burns in 22 patients and obtained histological samples for burn determination with hematoxylin and eosin and vimentin immunohistochemical staining. Additionally, sequential scans and tissue specimens were obtained on 10 burns at 24, 48, and 72 hours. A statistically significant inverse relationship was noted between burn depth and the laser Doppler perfusion index. Laser Doppler perfusion index values greater than 1.3 predicted a superficial dermal burn with 95% sensitivity and 94% specificity. Superficial dermal burns exhibited increased perfusion in the early burn period. Wounds showed a progressive decline in perfusion and a progressive increase in the depth of injury during a 72-hour period. This study demonstrates the advantage and accuracy of using a noncontact laser Doppler to differentiate deep dermal from superficial partial thickness burns in the extremities.     

Microvascular assessment of burn depth conversion during varying resuscitation conditions.

Conversion of partial- to full-thickness injuries, even after the burning has stopped, remains a significant clinical problem. We developed a rat model with a wide range of burn depths to study this phenomenon by microvascular assessment. Fifty-four male Sprague-Dawley rats weighing 460 g on average were studied. Real-time tissue monitoring of pH, paCO2, and paO2 was achieved by placement of a continuous blood gas monitor transducer in the aorta. Ten, 2-cm x 2-cm burns were created on each animal with milled aluminum templates (100 degrees C) with varying contact times. Conversion of burn depth in these wounds was documented by serial laser Doppler imager scanning over a 5-hour period. Animals received Ringer's lactate resuscitation at 0, 2, 4, 6, and 8 ml/kg/%burn. Serial laser Doppler scanning directly demonstrated progressive loss of perfusion to partial-thickness burns dependent upon the amount of fluid resuscitation. Conversion of partial- to full-thickness burns in this rat model (documented by laser Doppler microvascular assessment) was dependent upon how the animals were resuscitated.     

Serial measurements increase the accuracy of laser Doppler assessment of burn wounds

Traditional methods of judging burn depth by clinical evaluation of the wound based on appearance and sensation remain in wide use but are subject to individual variation by examiner. In addition to the clinical difficulties with burn wound management, observer dependency of wound assessment complicates clinical trials of burn wound therapy. A laser Doppler flowmeter with a multichannel probe was used to measure burn wound perfusion as a tool to predict wound outcome. Serial measurement with laser Doppler flowmetry had an 88% specificity and a positive predictive value of 81% for identifying nonhealing wounds. These results suggest that laser Doppler flowmetry is a potentially useful tool for burn wound assessment.     

温度控制对大面积烧伤休克期患者创面涂药效果的影响

目的探讨温度控制对大面积烧伤休克期患者创面涂药效果的影响。方法将72例大面积烧伤患者按入院先后分成观察组（36例）和对照组（36例）。观察组患者在大面积烧伤休克期创面涂药进行温度控制（即用药加温、躯体保温）,通过对患者躯体保温、创面用药加温等方法分次完成涂药;对照组创面涂药按常规进行。观察两组患者涂药前后的心率、体温变化,寒颤、肢端湿冷的发生率。结果对照组患者涂药后体温明显低于涂药前,心率明显快于涂药前,观察组患者涂药后的心率、体温变化以及寒颤、肢端湿冷发生率明显低于对照组患者,两者差异有统计学意义（P〈0.01）。结论对大面积烧伤休克期患者创面涂药时进行温度控制,对患者的体温、心率、末稍循环影响小,患者能较平稳度过休克期。     

The relationship of body mass index and functional outcomes in patients with acute burns.

Obesity may contribute to the functional decline in elderly adults. It can also increase the risk of mortality in burn patients. However, little data exist regarding the relationship between obesity and functional outcomes in patients with burns. Data were collected regarding admission body mass index (BMI), length of stay, TBSA burn, inhalation injury, age, sex, discharge disposition, and discharge functional independence measure (FIM) scores for 221 patients. We used the classification and regression trees (CART) method to determine the strongest predictors of discharge disposition and FIM scores. Patients older than 59, with 0 to 30.75% TBSA burn, and a BMI of less than 27 were more likely to return home when compared with matched patients with a greater BMI. Regardless of age and BMI, patients with greater than 30.75% TBSA burn were less likely to return home (27.6%) posthospitalization when compared with patients with less than 30.75% TBSA burn (82.8%). Patients aged 54 to 72 years with less than 22.50% TBSA burn and a higher BMI (>25.15) demonstrated lower FIM locomotion scores than corresponding patients with a lower BMI (<25.15). Older patients (>72.5 years) with burns less than 22.50% TBSA and a larger BMI (>31.25) had lower transfer FIM scores when compared with matched patients with a smaller BMI (< or =31.25). Among patients with greater than 22.50 TBSA burn, women demonstrated lower FIM transfer and locomotion scores when compared with men. BMI may contribute to lower functional scores and the likelihood of discharge to an inpatient setting in elderly patients with less severe burns.     

Changes in coagulation factors in patients with burns during acute blood loss

A prospective study was undertaken to determine the change in coagulation factors in patients undergoing tangential excisions of burn wounds when red blood cells preserved with ADSOL (adenine, dextrose, saline, and mannitol) and crystalloid solution were used for volume replacement. Nine patients with burns were studied, three on two separate occasions. No patient had a history of a bleeding disorder or had taken aspirin within 10 days of surgery. Results of preoperative coagulation studies were all within normal limits. The initial levels of coagulation factor and rates of removal were compared with those of 12 patients without burns who were undergoing elective surgery and who also had massive intraoperative blood loss. Coagulation factor levels measured included the platelet count, fibrinogen, factors V, VIII, and IX. These were determined before blood loss and each time loss and replacement of one third of a patient's calculated blood volume occurred during a tangential excision of a burn wound. The data showed that patients with burns have significantly higher baseline levels of platelets, fibrinogen, and factor VIII than patients without burns do. The removal rates of platelet and factor IX are significantly lower among patients with burns than among patients without burns. No patient in the study group developed a coagulopathy or received fresh frozen plasma or platelet supplementation. These findings suggest that the intraoperative blood losses that occurred during tangential excisions of burn wounds were made safe by the higher than normal preoperative levels of platelets, fibrinogen, and factor VIII and by the slow wash-out curve for platelets and factor IX. Prophylactic use of either fresh frozen plasma or platelet concentrates is not indicated unless a specific deficit or coagulopathy has been identified.     

A prospective, randomized trial of Acticoat versus silver sulfadiazine in the treatment of partial-thickness burns: which method is less painful?

Despite recent improvements in analgesia, pain control during dressing changes continues to be a major challenge in patients with burns. We investigated two different dressing modalities to compare how much pain the patient experienced during and after the dressing change. Patients with partial-thickness burns that required only topical wound care were assigned randomly to treatment with Acticoat (Smith and Nephew USA, Largo, FL) or silver sulfadiazine (AgSD). The outcome variable was pain during wound care, which was measured using visual analog pain scores. The mean visual analog pain scores for the wounds treated with Acticoat or AgSD wounds were 3.2 and 7.9, respectively (P < .0001; paired Student's t-test). In 41 of the 47 paired pain score observations, the pain in the wound treated with AgSD was perceived as greater than in the wound treated with Acticoat. Burn wound care with Acticoat is less painful than burn wound care with AgSD in patients with selected partial-thickness burns.     

Efficacy of mupirocin in methicillin-resistant Staphylococcus aureus burn wound infection.

Methicillin-resistant Staphylococcus aureus strains (MRSA) have become increasingly prevalent as nosocomial pathogens, especially in burn wounds. MRSA constituted 38% of all S. aureus isolates in our 25-bed burns unit despite the utilization of a combination of 1% silver sulfadiazine and 0.2% chlorhexidine as topical therapy. Mupirocin, a new antibiotic, has proved in vitro and in vivo to be highly effective in the treatment of MRSA infections. A prospective clinical trial with mupirocin ointment in MRSA burn wound infection was untertaken. Forty-five children with 59 discrete burn wounds and from whom MRSA were isolated were treated with 2% mupirocin ointment under occlusive dressings, applied twice daily for 5 days. The average burned area treated was 8% (range, 2 to 20%) of the total body surface area. The burn wounds were assessed clinically and bacteriologically daily. Mupirocin eliminated MRSA in all 59 wounds treated, with the maximum therapeutic response seen within 4 days. In three wounds, gram-negative organisms persisted after 5 days of topical therapy. Treatment was well tolerated by all children. We recommend that mupirocin in its present polyethylene glycol base should be used only on a selective basis, when current prophylactic topical therapy has failed to control MRSA infection in burns of less than 20% of the total body surface area, and that it should be applied only for a limited period of 5 days. The safety and the efficacy of mupirocin in burns exceeding 20% of the total body surface area need to be established.     

Quantitative assessment of graded burn wounds in a porcine model using spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI)

Accurate and timely assessment of burn wound severity is a critical component of wound management and has implications related to course of treatment. While most superficial burns and full thickness burns are easily diagnosed through visual inspection, burns that fall between these extremes are challenging to classify based on clinical appearance. Because of this, appropriate burn management may be delayed, increasing the risk of scarring and infection. Here we present an investigation that employs spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI) as non-invasive technologies to characterize in-vivo burn severity. We used SFDI and LSI to investigate controlled burn wounds of graded severity in a Yorkshire pig model. Burn wounds were imaged starting at one hour after the initial injury and daily at approximately 24, 48 and 72 hours post burn. Biopsies were taken on each day in order to correlate the imaging data to the extent of burn damage as indicated via histological analysis. Changes in reduced scattering coefficient and blood flow could be used to categorize burn severity as soon as one hour after the burn injury. The results of this study suggest that SFDI and LSI information have the potential to provide useful metrics for quantifying the extent and severity of burn injuries.OCIS codes: (110.4234) Multispectral and hyperspectral imaging, (170.3660) Light propagation in tissues, (170.3880) Medical and biological imaging, (170.6510) Spectroscopy, tissue diagnostics     

Microcirculation in hypertrophic scars after burn injury

Hypertrophic scar formation is a common complication after burn injury. Early active scars show hyperemic appearances that change as the scar matures. This is a report on microcirculation in hypertrophic scars after burn injury among 50 Chinese patients with a laser Doppler flowmeter. The average period of follow-up for the patients was 20 months. The microcirculatory response in scars to vasodilation (heat) stimulus was studied. Significant differences (p less than 0.0001) were demonstrated between scars of different clinical grades of maturity when compared with normal skin. The qualitative and quantitative differences in microcirculatory blood flow were correlated with site variations and different physiologic demands from different grades of scars. The study showed that laser Doppler flowmetry was useful in the clinical grading assessment of or for scar maturity.     

The use of intestinal antibiotics to delay or prevent infections in patients with burns

Bacterial colonization and infection of wounds in seriously burned patients often comes from the patient's indigenous bowel flora. A prospective randomized clinical trial that involved 30 patients with 20% or greater total body surface area burns was undertaken to evaluate the use of a standard antibiotic bowel preparation in the delay or prevention of bacterial colonization of the burn wound and sepsis. Certain enteric bacteria were seen less frequently in the treated group (Enterobacter organisms), but other bacteria appeared more often in the treated group (Proteus organisms and enterococci). The average time of colonization of the burn wounds was 6.1 days in the treated group and 6.7 days in the control group. Blood cultures were positive for enteric organisms earlier in the treatment group. Pseudomonads appeared earlier in the wound and blood cultures of the treated group than in the control group. The effect of antibiotic bowel suppression in patients with burns is varied and unpredictable. The bowel preparation may select certain organisms and lead to earlier colonization of the wounds. Overall outcome and survival was not improved by the use of an antibiotic bowel preparation in these patients.     

Blood transfusion in burns: what do we do?

Over 11 million units of blood are transfused yearly in the United States. Although blood transfusion is common in burns, data are lacking on appropriate transfusion thresholds. The purpose of the study was to identify current burn center physician blood transfusion practices. A 30-question survey of blood transfusion practices was developed and sent to burn center directors. The survey assessed demographics, burn experience, and blood transfusion thresholds. Physicians were asked to list factors affecting their blood transfusion thresholds and then to give their blood transfusion threshold for patients based on age and percent burn. The final section presents three case scenarios with alterations in one physiological parameter to assess the effect on transfusion thresholds. A total of 55 of the 180 surveys (31%) were returned. Mean number of burn beds was 15.7 +/- 1.4, with 264 +/- 25 burn admissions per year. The respondents had been in burn care for 15.9 +/- 1.4 years. Their mean hemoglobin transfusion threshold was 8.12 +/- 1.7 g/dl. The most frequent reasons for transfusion were ongoing blood loss (22%), anemia (20%), hypoxia (13%), and cardiac disease (12%). Inhalation injury influenced the decision to transfuse blood in 34%. The hemoglobin level below which respondents would transfuse blood increased with increasing TBSA burn, history of cardiac disease, acute respiratory distress syndrome, and age. Blood transfusion thresholds in burns vary based on burn percentage, age, and presence of cardiac disease. To date, no standard of care exists for blood transfusions in burns. Future prospective studies are needed to determine the appropriate use of blood in burns.     

Enzymatic debridement as an effective treatment for combined flame and chemical burns caused by e-cigarettes

Since its introduction on the market in 2007, the number of reports on injuries caused by the ignition or explosion of electronic nicotine delivery systems (ENDS) has increased significantly.Two male patients have been treated at our burn center, the for ENDS-related injuries. Their batteries came into contact with metal objects stored in their pants pockets, resulting in a short circuit and finally ignition. In both patients, the combined flame and chemical burn wounds were initially irrigated with water upon arrival at the emergency department, leading to increased levels of pain. In our burn center, the wounds were extensively cleansed which led to a subsequent drop in NRS-scores. Laser Doppler Imaging showed a clear indication for surgery as both patients suffered a partial-thickness burn, with one patient having a patch of full-thickness burn as well. We swiftly performed an enzymatic debridement in both patients, followed by conservative wound management. Although enzymatic debridement is not generally recommended in the treatment of chemical burns, we successfully made use of this treatment option.Different authors advocate the use of mineral oils to irrigate or cover alkali burns, as contact between the chemical compounds and water can set off an exothermic reaction, leading to further injury. We believe that a hypertonic rinsing solution could be recommended as well in an emergency setting and we want to stress the importance of rapid removal of the chemical compounds in suspected chemical burns as well as swift debridement.     

Burn excision with contact neodymium: YAG laser

The newest laser modality, the contact Neodymium: YAG laser, was compared with the standard steel scalpel in excisions of full-thickness burns. Six patients with deep burns of variable sizes were included in this pilot study. The area to be operated on in each patient was divided into two areas resembling each other as much as possible in size, tissue type, and depth of injury. The results suggest that bleeding was diminished by 44% in contact laser surgery compared with the steel scalpel. Still the difference was not significant. There was no impairment of graft take after laser surgery compared with the steel scalpel. However, the laser method caused a significant increase (p less than 0.02) in operating time. The contact Nd: YAG laser can be recommended for excision of relatively small deep burn injuries, especially in areas in which bleeding is a problem with other methods.     

Burn depth evaluation with fluorometry: is it really definitive?

Clinical evaluation of burn depth soon after injury is subjective, based on gross visual assessment. Previous investigators have quantified this process using fluorometry. Their studies show fluorescein levels in full-thickness burns to be far below control levels and partial-thickness burns to be about 60% of nonburned skin. In both rat and human models, 59 burn sites (eight rats) and 37 burn sites (seven patients) were assessed. Readings were taken for three hours on the rats and one hour on the patients during the first 48 hours, and the procedure was repeated for five days postburn. Maximum values during these periods were determined for burn and nonburn sites, and background levels were subtracted from these values. The rate of fluorescein uptake and the peak times for burn and nonburn sites were then compared. Actual depth of burn was determined by whether or not healing had occurred. The results showed no significant difference between partial-thickness and full-thickness burns using fluorometry, as standard deviations in both models for both depths of burn were large. Therefore, fluorometry did not provide a definitive evaluation of burn depth. These results differ from those reported by previous investigators.     

Laser Doppler flowmetry for the early detection of hypertrophic burn scars

In this preliminary study it was hypothesized that patients with hypertrophic scars have increased microcirculatory perfusion in the areas of scarring. Sixteen former patients whose burn injuries involved less than 30% TBSA and who required autologous skin grafting were evaluated using laser Doppler flowmetry. Data grouped at three-week intervals showed higher flow values in patients with hypertrophic scarring than in those with non-hypertrophic scars. These initial data suggest that hypertrophic scars may be associated with increased microcirculatory blood flow. These values are elevated early and could possibly serve as an early indicator for the occurrence of hypertrophic scarring.     

强化血糖调控在危重烧伤患者治疗中的临床价值

目的评价强化血糖调控对危重烧伤患者治疗过程中的高血糖反应、糖代谢、创面愈合能力及预后的影响。方法选择36例严重烧伤无糖尿病史的男性患者,随机分为两组,试验组（18例）予以强化胰岛素治疗,而对照组（18例）则予以常规胰岛素治疗,两组均于伤后3~7 d内行切、削痂植皮手术,术后连续14 d每晨皮下注射重组人生长激素（rhGH）。观察两组患者血糖、血钾的变化,记录两组创面愈合时间、住院时间、并发症发生率及病死率。结果试验组治疗过程中血糖、血钾水平均显著低于对照组组（P〈0.05）,而且试验组的创面愈合时间、住院时间、并发症发生率及病死率也少于对照组（P〈0.05）。结论强化血糖调控能有效控制严重烧伤后的高血糖反应和消除rhGH的副作用,促进糖代谢,缩短创面愈合时间,减少并发症发生率及病死率。     

强化血糖调控在危重烧伤患者治疗中的临床价值

目的评价强化血糖调控对危重烧伤患者治疗过程中的高血糖反应、糖代谢、创面愈合能力及预后的影响。方法选择36例严重烧伤无糖尿病史的男性患者,随机分为两组,试验组(18例)予以强化胰岛素治疗,而对照组(18例)则予以常规胰岛素治疗,两组均于伤后3~7 d内行切、削痂植皮手术,术后连续14 d每晨皮下注射重组人生长激素(rhGH)。观察两组患者血糖、血钾的变化,记录两组创面愈合时间、住院时间、并发症发生率及病死率。结果试验组治疗过程中血糖、血钾水平均显著低于对照组组(P0.05),而且试验组的创面愈合时间、住院时间、并发症发生率及病死率也少于对照组(P0.05)。结论强化血糖调控能有效控制严重烧伤后的高血糖反应和消除rhGH的副作用,促进糖代谢,缩短创面愈合时间,减少并发症发生率及病死率。     

Determination of burn depth with noncontact ultrasonography

Early excision and grafting is the current treatment of choice for deep dermal and full-thickness burn wounds that will not heal spontaneously within 3 weeks. The time needed for the burn wound to heal is estimated with clinical assessment of the burn depth; this is often an inaccurate method. Therefore we have developed a new and unique noncontact ultrasonographic method to estimate burn depth. This study was designed to determine the practical utility and accuracy of noncontact ultrasonography for the assessment of burn depth. Seventy-eight burn sites and 42 normal skin sites (control sites) of 15 patients (age, 18-63 years) with burns of 2% to 35% total body surface area were evaluated. The burn sites were scanned with a prototype noncontact ultrasonographic system 1 and 3 days after the burn injuries. The probe was held 1 inch from the skin, and the time spent on each site was approximately 5 minutes. The ultrasonographic results were interpreted by an investigator who was blinded to the clinical findings. Clinical assessment of the burn wounds was made on the same days by 2 experienced physicians who were blinded to the results of the ultrasonography. The investigators were asked to categorize the burn wounds into those that would heal within 3 weeks and those that would not. With this method, we were able to visualize the epidermis, dermis, and dermal-fat interface in normal skin. The destruction of the dermal-fat interface was interpreted as a deep burn, which would not heal within 3 weeks. The overall accuracy of the noncontact ultrasonography in the prediction of which burn wounds would heal within 3 weeks was 96%. The results of this study show that noncontact ultrasonography will allow for the rapid evaluation of burn depth with high accuracy, without contacting the patient, and without causing pain or discomfort.