Alterations of mental status and thyroid hormones after thermal injury.

In 16 burn patients, mean values for serum T4 and T3, their T3 uptake-derived free indices (FT4I and FT3I) and dialysis-derived free concentrations (FT4 and FT3) were depressed (all P less than 0.001) compared to respective means in 13 normal subjects. In the patients, the free hormone indices were relatively more depressed below control values than were the free hormone concentrations. However, within the group of burn patients, variation in FT4I reflected that of FT4 (r = 0.91), and variation in FT3I reflected that of FT3 (r = 0.93). We then studied serum T4, T3, and their free indices in 134 patients (burn size, 6-96% of the skin area), including 45 nonsurvivors, none of whom received steroid, dopamine, or iodine treatment. At each sampling, the level of obtundation (LO) was determined on a 6-point scale from normal to deep coma. Whereas initially low mean FT4I values rose in survivors, they remained lower in nonsurvivors than in survivors until death in the nonsurvivors. In nonsurvivors, mean LO worsened in the first week and remained worse than that in survivors until death. Multiple regression analyses showed that for a given age or burn size, nonsurvival was better correlated with lower T4 or FT4I than with T3 or FT3I, but was even more closely correlated with worse LO (P less than 0.001). Exclusion of data obtained within 24 h of narcotic or tranquilizer doses did not weaken the relationship of nonsurvival with LO and FT4I. Nonsurvival after burn injury was associated with reduced T4, FT4I, and mental status for up to weeks before death, this association being independent of treatment with drugs acting on mental status or thyroid function.

Replacement therapy with modified immunoglobulin G in burn patients: preliminary kinetic studies.

Suppression of serum immunoglobulin G for periods ranging from days to weeks following thermal injury may enhance the risk of infection in burn patients. In an initial trial, we attempted to determine whether intravenous pulses of Immunoglobulin G (IgG) will establish and maintain normal serum IgG concentrations in this interval. The levels of endogeneous serum IgG in eight control patients, mean total burn size 45 percent body surface area (no IgG infusions), were measured by radial immunodiffusion on various postburn days. Commercially available reduced alkylated IgG (5 percent Gamimune, Cutter Biological, Berkeley, California) was infused in doses of 500 mg/kg twice per week in four patients (total burn size 32 percent) and once per week in five patients (total burn size 47 percent), beginning during the first postburn week. Circulating IgG was measured prior to each infusion and at three postinfusion times: (1) 15 minutes (peak), (2) one day, and (3) either day 3, 4, or 6. Surgery or blood transfusions prior to one of these time points invalidated kinetic analysis of some infusions. Exponential two-point decay constants for total serum IgG after each of 24 infusions were calculated separately for early (day 0-1) and later (day 1-3 or 1-4) postinfusion intervals and assessed by stepwise regression analysis to determine sources of variation in decay. Early decay was seen to be faster with larger burn size after accounting for variation of decay with preinfusion and peak IgG values. Later decay was not related to burn size. Maltose, a constituent of the IgG preparation, was detectable in serum for only four to eight hours after each infusion and may have contributed to a 20 percent increase in total serum glucose between four and eight hours postinfusion. Mean serum IgG in patients given infusions twice weekly was in the normal range after one infusion, about a week earlier than in untreated patients. Such infusions maintained normal IgG levels.

Thermal injury during pregnancy.

Nineteen pregnant women with burn areas ranging from 6 to 92% of the total body surface area were treated at the US Army Institute of Surgical Research between 1951 and 1974. A review of these cases led to the following observations and conclusions: 1) Pregnancy does not alter the maternal outcome after thermal injury. 2) Maternal survival is usually accompanied by fetal survival. 3) If the gravida's injury is lethal, the pregnancy will usually terminate spontaneously prior to her death. 4) Obstetric intervention is indicated only in the gravely ill woman whose complications (hypotension, hypoxia, or sepsis) jeopardize the life of the fetus. 5) A better understanding of the complications of major burns and the care available in modern burn units should improve the prognosis for burned pregnant patients.

Subeschar treatment of burn-wound infection.

Within a 24-month period, 454 patients were admitted with burns (average size, 33% of the total body surface [TBS]). Wound infection developed in 19, who subsequently were treated with subeschar antibiotics. The average burn size in those 19 patients was 63% of the TBS, with an average full-thickness injury of 47%. Five (26%) of the 19 survived, and five others died without evidence of wound infection, giving a would clearance rate of 52.6%. The five surviving patients (average burn size, 59% TBS) underwent excision of infected tissue, with split-thickness cutaneous autograft closure of the burn wound, after the course of subeschar antibiotic infusion. All surviving patients were infected with Pseudomonas aeruginosa. Subeschar infusion of semisynthetic penicillins, therefore, is an effective adjunct in the care of the patient with Pseudomonas burn-wound infection.

Excision of the burn wound in patients with large burns.

The known major determinants of survival for patients with burn injury are age, burn size, inhalation injury, and infection. The clinical courses of 210 patients with burns of 30% of the body surface or greater treated from Jan 1, 1983, through Dec 31, 1985, were reviewed to determine whether excision of the burn wound could be identified as a factor in survival after massive burn injury. The predominant site of infection changed from the burn wound to the lung, with pneumonia being the most common bacterial infection in patients whose wounds were treated as described. Effective topical control of bacterial proliferation and excision of the burn wound have resulted in replacement of invasive bacterial wound infection by nonbacterial burn wound infection. The apparent advantages of excision, particularly in large burns, may reflect only patient selection, since only those patients who are considered to be physiologically stable and able to tolerate the physiologic stress of excision are considered for operation.

Comparison of quantitative microbiology and histopathology in divided burn-wound biopsy specimens.

We examined the association between quantitative microbiologic results and histopathologic findings in divided biopsy specimens from 200 burned patients. Microbiologic counts were determined as log10 colony-forming units per gram of disrupted tissue. Histopathologic results were scored on a scale of 1 to 6, values of 4 or greater indicating microbial invasion of viable tissue. Agreement of 96.1% was found between negative cultures, arbitrarily identified as those with fewer than 5 logs/g, and histologic absence of invasive infection. In sharp contrast, however, histologic invasion occurred in only 36% of specimens with positive cultures. Though low tissue counts are essentially synonymous with negative histologic findings, quantitative microbiology is not a diagnostic substitute for histologic examination, since high tissue counts quite commonly do not indicate invasion. The principal value of quantitative burn-wound biopsies is the demonstration of predominant burn-wound flora.

What's in a name? Is methicillin-resistant Staphylococcus aureus just another S aureus when treated with vancomycin?

Methicillin-resistant Staphylococcus aureus (MRSA) strains, principally resistant to penicillinase-resistant penicillins and aminoglycosides, are increasingly common hospital isolates. We have examined the significance of MRSA colonization and infection in 1100 consecutively admitted, seriously burned patients in whom vancomycin was used to treat all staphylococcal infections. Colonization with S aureus (SA) was identified in 658 patients, in 319 of whom MRSA colonization was identified. Two hundred fifty-three SA infections occurred in 178 patients; of these infections, 58% were pulmonic and 38% were bacteremic. Methicillin-resistant SA infections occurred in 58 of the SA-infected patients. A severity index, based on multiple-regression analysis of mortality as a function of burn size and age in the study population, was used to estimate expected mortality. We demonstrated no measurable increase in mortality attributable to MRSA in this population of burned, SA-infected patients. The results question the clinical and economic value of added control practices, such as closing of units, refusal of transfer or admission, added isolation, treatment of carriers, furlough of colonized staff, and other expensive measures that are specifically directed at prevention of MRSA infections in critical care areas.

Microbial colonization in a new intensive care burn unit. A prospective cohort study.

Renovation of an existing intensive care burn facility required closure for ten months. An interim eight-bed open intensive care ward (B) was established in a burn convalescence ward. The renovated unit (A) contained nine single-bed intensive care rooms and seven intermediate-level care beds in four rooms. Patients admitted to unit A were treated as a cohort. The first 25 admissions to unit A and the last 25 admissions to ward B meeting the inclusion criteria were compared. Microbial colonization was monitored by a fixed protocol of admission and multiple weekly sputum, wound, stool, and urine cultures. During intensive care, both cohorts exhibited the same incidence of gram-negative wound, sputum, and urine colonization. Occurrence of antibiotic-resistant organisms was the same. No evidence of bacterial cross-contamination was observed between A and B. A continuation of Providencia stuartii and Pseudomonas aeruginosa (type 15) endemics occurred in B. The collected data demonstrate that the A cohort was colonized with new, similar but distinct gram-negative organisms and indicate that cohort separation may be a practical way of eliminating endemic resistant gram-negative organisms from burn units.

A decade of reduced gram-negative infections and mortality associated with improved isolation of burned patients.

OBJECTIVE: To compare the incidence of gram-negative bacteremia (GNB) and mortality in patients with large burns (> or = 20% of total body surface) hospitalized in either an open ward (OW) or a single-bed isolation (IW) environment. DESIGN: Retrospective cohort study. SETTING: The US Army Institute of Surgical Research, Burn Center, Ft Sam Houston, Tex. PATIENTS: Two thousand five hundred nineteen consecutive patients with large burns divided into two 10-year cohorts. Patients in the first cohort period were treated under OW conditions; patients in the second cohort period, under IW conditions. Infection (bacteremia) data were from a laboratory database. A microbial surveillance system was used to monitor patient isolation. Mortality was compared with predicted mortality derived by logistic regression of outcome, burn size, and age of patients without bacteremia in the study. MAIN OUTCOME MEASURES: Presence of GNB and survival. RESULTS: The incidence of GNB was higher in the OW cohort (31.2%) than the IW cohort (12.0%) (P < .001). The postinjury time of first GNB was delayed in the IW vs the OW cohort (28.9 days vs 11.8 days, respectively) (P < .001). For patients who had GNB in the OW cohort, mortality was higher than predicted (observed-predicted mortality ratio, 1.61) (P < .001). Such increased mortality was not present in the IW cohort. Multiple antibiotic-resistant gram-negative pathogens were endemic in the OW cohort. There was no evidence of cross infection or endemic conditions with multiple antibiotic-resistant gram-negative pathogens in the IW cohort. CONCLUSION: Improvements in isolation of burned patients were associated with decreased incidence of GNB, delayed postinjury time of GNB, and improved survival. Improved survival is likely related to decreased susceptibility as a result of longer exposure to the benefits of treatment and wound closure. These results suggest that, in patients with severe burn injuries, gram-negative infections and the related mortality can largely be prevented.

Improved survival of burned patients with inhalation injury.

OBJECTIVE: To study a cohort of patients treated at the same institution and to compare that patient population with that of a previous report documenting the comorbidity of inhalation injury and pneumonia. Specifically, we wanted to determine whether there had been an improvement in survival of patients suffering inhalation injury. DESIGN: A retrospective review. SETTING: The US Army Institute of Surgical Research, Ft Sam Houston, Tex, a 40-bed burn intensive care referral unit. SUBJECTS: One thousand two hundred fifty-six thermally injured patients treated between January 1985 and December 1990. MAIN OUTCOME MEASURE: A comparison of pneumonia frequency and ultimate survival of the current cohort of patients as compared with a previously generated stepwise logistic analysis predicting mortality on the basis of 1980 to 1984 patient data. RESULTS: Of 1256 burned patients admitted between 1985 and 1990, there were 330 identified as having inhalation injury. These patients were older (35.0 vs 26.6 years) and had more extensive burns (41.1% vs 18.3%) and a higher mortality (29.4% vs 5.0%) than did the patients without inhalation injury. When compared with a mortality predictor generated from 1980 through 1984 patient data, patients in the most recent period had a lower mortality than predicted (29.4% vs 41.4%). Patients with less severe injury (positive xenon scan, negative results of bronchoscopy; n = 85), although having a similar incidence of pneumonia (13.1% vs 19.5%) as the same group from 1980 through 1984, accounted for the most improvement in survival. The 3.6% mortality was significantly less than the predicted rate of 15.7%. Patients with positive results of bronchoscopy (n = 245) also showed some improvement in outcome from that predicted (38.3% vs 50.2%) despite no change in the rate of pneumonia (46.9% vs 48.5%). Further improvement in survival was realized in those patients supported with high-frequency ventilation. Although their age (33.9 vs 36.3 years), burn size (46.0% vs 45.5%), and duration of intubation (16.8 vs 15.1 days) were similar to those of conventionally treated patients, mortality was significantly less than predicted (16.4% vs 40.9%) and less than that in patients treated with conventional ventilation (16.4% vs 42.7%). CONCLUSIONS: The improvement in survival of patients with inhalation injury represents the aggregate effects of the general improvement and outcome of all burned patients, the prevention of pneumonia by high-frequency ventilation, and the reduced mortality from the pneumonias that did occur.

Alterations in intestinal permeability after thermal injury.

Alterations in intestinal permeability have been postulated to occur after thermal injury. We evaluated the status of intestinal permeability during the first 2 postburn weeks in 15 subjects by measuring the differential excretion of enterally administered lactulose and mannitol. The mean age and burn size of the patients were 32.7 +/- 3.6 years and 53.3% +/- 5.1% of the total body surface area, respectively. Ten healthy volunteers were also studied. The lactulose-mannitol excretion ratio was 0.159 +/- 0.017 for the patients and 0.017 +/- 0.003 for controls. The increased ratio did not correlate with burn size or postburn day. Patients who developed significant clinical infections during their first 2 postburn weeks had lactulose-mannitol ratios on postburn day 2 that were significantly higher than those of controls and patients who did not develop infections. This suggests a relationship between susceptibility to infection and early alterations in intestinal permeability.

Effects of granulocyte-macrophage colony-stimulating factor in burn patients.

We studied the effects of granulocyte-macrophage colony-stimulating factor in burn patients. Serial measurements of granulocyte oxidative function were obtained in treated patients and in a group of controls matched for age and total burn size. The administration of granulocyte-macrophage colony-stimulating factor resulted in a 50% increase in mean leukocyte counts. Both groups showed significant baseline increases in granulocytic cytosolic oxidative function. Treated patients showed normal stimulated cytosolic oxidative function, which was significantly depressed compared with that of untreated patients. Myeloperoxidase activity was increased in treated patients during the first postburn week but then declined to normal levels. Untreated patients had a significant increase in myeloperoxidase activity for the first 3 weeks following injury. Untreated patients exhibited a significant decrease in superoxide activity during the second 3 weeks following injury. Treated patients demonstrated normal superoxide activity.

Fungal burn wound infection. A 10-year experience.

To evaluate our experience with fungal burn wound infection, we performed a 10-year review for comparison with our experience with bacterial burn wound infection. During the study period, a marked decline occurred in bacterial wound infection but not in fungal wound infection. Patients with either bacterial or fungal burn wound infection had massive injury, with burn size averaging greater than 50% of the total body surface area. Factors that appear to have markedly reduced bacterial burn wound infection, including patient isolation, topical chemotherapeutic agents, and burn wound excision, do not appear to have had a similar effect on fungal wound infection. The mechanism of spread and colonization of fungi, and the lack of effective topical chemotherapeutic antifungal agents, may explain in part our findings.

Effects of environment on infection in burn patients.

Burn patients in an early cohort (n = 173) treated in an intensive care ward without separate enclosures were compared with a later cohort (n = 213) treated in a renovated unit with separate bed enclosures. The number of patients developing infection was significantly reduced in the late group. Observed mortality was compared with mortality predicted on the basis of burn size and age alone. Reduction in observed compared with predicted mortality, inapparent in the early group, was seen in the late group and was restricted to the subgroup of patients with predicted mortality of 25% to 75%, in which the observed mortality of 28.3% was less than the predicted mortality of 48.7%. The incidence of infected patients was reduced from 58.1% in the early cohort to 30.4% in the late cohort. In comparison of the early cohort with the late cohort, the overall proportion of patients with bacteremia was reduced from 20.1% to 9.4%, while the incidences of both pneumonia and burn wound invasion remained unchanged. Providencia and Pseudomonas species, endemic in the early cohort, were eliminated in the late cohort. Reduction of infection by environmental manipulation in burn patients was possible and was associated with improved survival.

Burn center care for patients with toxic epidermal necrolysis.

BACKGROUND: Toxic epidermal necrolysis (TEN) is a life threatening exfoliative disorder that is most commonly precipitated by the administration of a medication. Efforts to reduce morbidity and improve survival have brought into question the use of corticosteroids and recommend the transfer of patients to a burn center to facilitate wound care. STUDY DESIGN: This study evaluated the correlation of measures of disease severity and impact of treatment strategies on morbidity and mortality in patients with TEN. The records of all patients with TEN admitted to the United States Army Institute of Surgical Research during a 12 year period were reviewed. Patient characteristics, etiologic agents, time to referral of patients to the burn center, corticosteroid therapy, and other demographic features were studied. Univariate and multivariate analyses were used to determine the significance of these factors with respect to outcome. RESULTS: The sulfonamides and phenytoin were the most frequently identified etiologic agents. Patients at the extremes of age had a higher mortality rate. The period of hospitalization was longer in patients transferred to the burn center more than seven days after skin slough. Percent of epidermalysis, white blood cell count nadir, and corticosteroid administration for more than 48 hours were independently associated with mortality. CONCLUSIONS: These data indicate that the sulfonamides and phenytoin are the most common etiologic agents, expeditious transfer to a burn center reduces morbidity, and corticosteroid administration dramatically increases mortality.

Evaluation of serum visceral protein levels as indicators of nitrogen balance in thermally injured patients.

The use of serum visceral protein concentrations as predictors of nitrogen balance was assessed during the first 4 weeks following thermal injury. The correlation between nitrogen balance and serum albumin was not significant. Statistically significant correlations were found between nitrogen balance and serum prealbumin, retinol-binding protein, and transferrin. However, even the best correlation (retinol-binding protein, r = 0.388) was too weak to permit prediction of nitrogen balance on the basis of the visceral protein concentration. The correlation between change in direction of nitrogen balance and change in direction of protein concentration over time showed all four visceral proteins to be poor predictors of change in nitrogen balance. The efficiency was less than 50% for each visceral protein. Stepwise multiple regression analysis performed to determine which indices were most closely correlated with nitrogen balance showed that a calculation using readily available information (nitrogen intake, postburn day, percent total body surface burned, and age) provided better prediction of nitrogen balance (r = 0.765) than any of the visceral protein concentrations. In view of these findings, measurement of serum visceral protein concentrations to monitor adequacy of nutritional support seems an unwarranted expense in patients with thermal injury.

Accuracy of urinary urea nitrogen for predicting total urinary nitrogen in thermally injured patients.

Estimations of total urinary nitrogen from measured urinary urea nitrogen are commonly used in calculating nitrogen balance. Recently published studies suggest the urinary urea nitrogen/total urinary nitrogen relationship is inconstant and total urinary nitrogen must be directly measured in burned patients. This study addresses the relationship of urinary urea nitrogen to total urinary nitrogen after thermal injury. Two hundred random 24-hour urine collections obtained from 45 thermally injured patients (mean burn size 59 +/- 28%, mean age 40.5 +/- 17.2 years) between 1 and 354 days postburn were analyzed for total urinary nitrogen and urinary urea nitrogen. Regression analysis relating total urinary nitrogen to estimated total urinary nitrogen (urinary urea nitrogen x 1.25) revealed a linear relationship (r = .936, p < .001). The mean urinary urea nitrogen/total urinary nitrogen ratio was 0.77 +/- 0.10 and was not significantly correlated with percent burn, age, or postburn day. Mean nitrogen balance calculated from measured urinary urea nitrogen in these patients was -5.7 g, and that calculated from measured total urinary nitrogen was -6.3 g. This difference, although statistically significant, is of little consequence for clinical use. Contrary to recent reports, we found the urinary urea nitrogen to be sufficiently predictive of total urinary nitrogen for practical application, and do not consider routine total urinary nitrogen measurements necessary for the nutritional care of thermally injured patients.

Thermal trauma resulting from motor vehicle operation or maintenance.

Burn injury may result from the operation or maintenance of motor vehicles. We reviewed the experience of one burn center with injuries related to motor vehicle use over the 6 year period 1987-1992. One hundred and fifty patients with motor vehicle related burns were identified comprising 11.3% of all admissions for this period. The mean extent of burn injury was 22.8% total body surface area with a mean full thickness (third degree) burn size of 11.7%. The average hospital length of stay was 42.41 days. The most common mechanisms of injury were collisions resulting in fire (n = 48), carburetor priming (n = 37) and scalding from radiator fluid contact (n = 27). Burns resulting from vehicle operation or maintenance are costly and potentially preventable.

Aeromonas bacteraemia in burn patients.

Human aeromonas infection is uncommon and is usually associated with immunosuppression, chronic disease or trauma in an aquatic setting. Burn injury may induce a state of immunosuppression, making the thermally injured patient a suitable host for aeromonas infection. We reviewed the experience of one burn centre with this pathogen. Retrospective examination of blood culture results from 8151 patients admitted between 1959 and 1994 disclosed eight patients with clinically relevant Aeromonas hydrophilia bacteraemia. Five were burned outside the USA. Aquatic exposure was known or suspected in only three cases. Five of the eight patients died. Aeromonas infection in burn patients is rare but may occur in the absence of aquatic exposure.

Suppurative chondritis: its incidence, prevention, and treatment in burn patients.

A retrospective study of 317 cases of suppurative otochondritis occurring in a population of 4794 burned patients successively admitted to one institution between 1967 and 1984 is presented. During the study interval, the incidence of the disease decreased from 20 percent to less than 3 percent in patients with burns of one or both ears. The bacterial species associated with chondritis, principally Pseudomonas aeruginosa and Staphylococcus species, did not change. Patients admitted later than the second postburn day exhibited a significantly greater incidence of chondritis. The crucial factors in prevention of this complication appear to be avoidance of pressure on burned ears and topical chemotherapeutic control of local Pseudomonas infection. Systemic antibiotic prophylaxis did not appear to influence the incidence in the studied population. Several approaches to clinical management of suppurative chondritis are reviewed.