Evaluation of leukocyte chemotaxis in vitro in thermally injured patients.

Leukocyte chemotaxis in vitro was studied by a modification of the Boyden technic in 46 thermally injured patients. All patients demonstrated a decrease in leukocyte migration through a Nuclepore filter toward a standard casein-serum chemotactic agent. Leukocyte chemotaxis was inversely correlated with burn size during the first 72 h after injury. After 72 h, leukocyte chemotaxis directly correlated with clinical status and was highly predictive for ultimate mortality. Since mortality was largely due to infection, these findings suggest that suppression of leukocyte chemotaxis may explain the susceptibility to opportunistic infection in thermally injured patients.

Depressed reflex vasomotor control of the burn wound.

Total leg blood flow was measured by venous occlusion plethysmography in five normals and 14 burned patients before and after 30 min of external heating. Leg surface temperatures were held constant, but rectal temperatures increased on the average of 0.4 to 0.5 degrees C in all subjects following this heat load. Leg blood flow increased by 56.0% in the controls, 63.2% in five patients with essentially no leg burn (mean burn size = 1.5% leg surface), and 9.6% in nine patients with major leg injuries (mean burn size 55% leg surface). Failure of reflex vasodilatation in the burned leg was evident up to 107 days postinjury even when the wound was well-healed. All subjects sweated freely from the unburned skin. In two patients, where arm and leg blood flows were measured simultaneously, flow to the uninjured arm increased while that to the injured leg remained unchanged. This lack of reflex vasodilatation in the burned limbs suggests either that wound vessels are denervated or that they are so dilated in the basal state that further dilatation is limited. The bulk of this and other data would support the denervation concept. This physical or chemical denervation could occur at the time of injury, be localised to the area of the wound, and result in loss of both neurogenic vasoconstrictor tone and active reflex vasodilatation.

Hormonal changes in burned hamsters.

Burned male Syrian hamsters (burn size 23% of body surface) exhibited reduced total (T4) and free (FT4) serum concentrations, a defect in T4 binding to serum proteins manifested by the T4 dialyzable fraction but not the in vitro T3 charcoal uptake, and reduced serum testosterone concentration. These changes are similar to those noted previously in burned humans. Unlike such patients, burned hamsters did not exhibit reduced serum T3 nor elevated rT3 concentrations in a reproducible manner. Pinealectomy performed before burning in hamsters did not prevent the burn-induced depression in serum T4 and testosterone.

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.

Platelet aggregation following defibrination with ancrod.

In vitro platelet aggregation was studied in dogs following defibrination with Ancrod. There was marked inhibition of aggregation immediately after defibrination. A gradual return toward normal aggregation was observed over the 96 hours study period, but aggregation was still abnormal at 96 hours after defibrination. There was an inverse and highly significant correlation between aggregation and fibrin degradation product level. Fibrinogen was not measurable after defibrination for the entire study period. Aggregation was thus independent of fibrinogen concentration in this study.

Update on current therapeutic approaches in burns.

Burn injury results in a rapid loss of intravascular volume as wound edema forms, which reduces the circulating blood volume and generates the need for fluid therapy to combat hypovolemia. Fluid resuscitation of a burn patient is usually carried out with isotonic, sodium- and chloride-containing fluids, such as lactated Ringer's solution. The initial 24 h resuscitation volume is based on the burn size and body weight of the patient. Following a successful resuscitation, the burn patient develops stereotypic neurohormonal and metabolic responses that, depending on the extent of injury, last for several weeks or months. Breathing of incomplete products of combustion by the fire victim produces inhalation injury, the incidence of which rises with increasing burn size and the severity of which is proportional to the duration of exposure. Systemic hypoxia from carbon monoxide toxicity causes early death; chemical airway injury increases mortality and predisposes to subsequent pneumonia that further reduces survival. The diagnosis of inhalation injury is made by bronchoscopy and/or xenon scan and therapy involves support of ventilation. Thermal destruction of the cutaneous mechanical barrier and the presence of nonviable avascular burn eschar as well as impairment of other host defenses render the burn patient susceptible to local as well as systemic infections. Care following resuscitation is focused on topical antimicrobial therapy, burn wound excision, and wound closure by grafting. Nutritional support and the prevention and control of infection are constant themes in burn patient management. A progressive improvement in general care of the acutely injured patient, prevention of shock, effective means of maintaining organ function, prevention and control of burn wound and other infections, and physiologically based metabolic support have significantly increased burn patient survival in recent decades.

Granulocyte oxidative activity after thermal injury.

BACKGROUND: Alterations in granulocyte function after thermal injury have been described. We have serially studied the level of granulocyte cytosolic peroxidase activity in 23 thermally injured patients during the first 6 weeks after injury. The patients' mean age and burn size were 35.1 +/- 15.7 years and 41.6% +/- 16.8% (range, 18% to 88%), respectively. Fourteen patients had concomitant inhalation injury, and the overall mortality rate was 4.3%. METHODS: Purified granulocytes were obtained from peripheral blood after red cell lysis and Ficoll-Hypaque (Pharmacia Inc., Piscataway, N.J.) gradient separation. Cells were loaded with dichlorofluorescin diacetate, and baseline fluorescence was measured by flow cytometry. After phorbol myristate acetate stimulation, fluorescence was measured again. Cells from unburned normal subjects were used as daily controls. RESULTS: The data are expressed as percent of stimulated control granulocyte fluorescence. Unstimulated patient granulocytes demonstrated a significantly higher baseline activity than did unstimulated controls (22.9% vs 15.4%; p < 0.05). Mean fluorescence from stimulated granulocytes was 114% of the control values (p < 0.05). CONCLUSIONS: Granulocytes from thermally injured patients exhibited a baseline increase in cytosolic oxidase activity, suggesting in vivo activation and a greater than normal oxidase activity after in vitro stimulation.

Evaluation of (1-sarcosine, 8-isoleucine) angiotensin II as a therapeutic agent for oleic acid-induced pulmonary edema.

(1-Sarcosine, 8-isoleucine) angiotensin II was assessed as a therapeutic agent for acute respiratory distress syndrome with oleic acid pulmonary edema in sheep used as an experimental model. Under general anesthesia with controlled mechanical ventilation with 100% oxygen, 32 sheep received oleic acid (0.075 ml/kg) intravenously. After oleic acid infusion, 20 animals were treated with continuous intravenous infusion of the angiotensin II analogue; nine received 300 ng/kg/min, six received 600 ng/kg/min, and five received 2000 ng/kg/min. Cardiopulmonary measurements were repeated every 30 minutes for 270 minutes. According to time-integrated PaO2, six of 15 animals of the groups given 300 and 600 ng/kg/min (43%) did not respond to the treatment. All animals responded in the group given 2000 ng/kg/min. Animals in the latter group had lower Qs/Qt, PaCO2, and airway resistance than had the control animals. Elevation of pulmonary vascular resistance was limited and mean arterial blood pressure was well maintained. These results reveal that (1-Sar, 8-Ile) angiotensin II is effective in the treatment of oleic acid-induced pulmonary edema.

Effect of blood transfusions on immune function. Part VI. Effect on immunologic response to tumor.

Transfusions are reported to increase the incidence of tumor metastasis in clinical studies and primary tumor growth in animal studies. We evaluated the effect of transfusions on immunologic response to primary and metastatic tumors in multiple rat models. One half of the animals were administered lactated Ringer's solution and one half ACI rat blood at the time of tumor challenge. In 80 rats a slow-growing colon tumor was implanted subcutaneously. At 4 months there were no significant differences in tumor size or leukocyte infiltration of the tumor. Similar results were obtained with a rapidly growing colon cancer. Analysis of T-lymphocyte subpopulations in both groups showed no differences. Rats transfused at the time of intravenous challenge with a suspension of 1 x 10(6) tumor cells had a mean survival time of 38.3 +/- 0.8 days and the control group had a mean survival time of 41.1 +/- 0.8 days (p = 0.016). One week after transfusion, natural killer cell lysis of tumor cells at a 100:1 effector/target cell ratio was 18.0% +/- 1.8% in the transfusion group and 23.0% +/- 1.3% in the control group (p = 0.034). In conclusion, transfusions in multiple rat cancer models did not affect primary tumor growth or the host's immunologic response to it but did significantly impair natural killer cell function and survival with tumor metastases.

Altered muscle metabolism in rats after thermal injury.

Burn injury is associated with an elevation in total body oxygen consumption, increased hepatic alanine uptake and conversion to glucose, and a negative nitrogen balance. The primary source of the alanine used for gluconeogenesis by the liver and of the nitrogen lost as urea is believed to be from skeletal muscle. Selected muscle regulatory enzymes and pyruvate and oleate oxidation rates were assayed for maximal activity during the postburn period. Male Sprague-Dawley rats that received 50% total body surface scald burns on the dorsum and abdomen were examined for citrate synthase (CS), phosphofructokinase (PFK), and glutamate-pyruvate transaminase (GPT) activity in uninjured muscle at 3, 7, 13, and 20 days postburn, and the ability of muscle to oxidize pyruvate and oleate was measured at 3 and 13 days after injury. Cs, PFK, and GPT activities increased significantly (p less than 0.05) by 13-20 days after injury in the soleus and diaphragm. The epitrochlearis showed no change in CS, but PFK and GPT were elevated within this time frame. The gastrocnemius muscle showed an elevated oleate oxidation rate at 13 days after injury, but no change at 3 days postburn. Pyruvate oxidation rates were unaltered. The results of this study indicate that during the postburn period several metabolic alterations occur in muscle. These adaptations include: (1) elevated CS activity which may be associated with increased oxidative capacity,, (2) increased PFK activity which implies that more substrate is being shuttled through the glycolytic pathway, (3) increased GPT activity which may reflect increased pyruvate conversion to alanine, and (4) increased oleate oxidation rates which demonstrate that muscle is utilizing more fatty acid substrates during the postburn period.

Nonthyroidal control of metabolism after burn injury: possible role of glucagon.

The endocrine basis for control of metabolism in nonthyroidal illness is not yet understood. Burn injury is associated with reduced serum concentrations of thyroid hormones and with resting hypermetabolism. One index of severity is total burn size (TBS, % body surface). After overnight fasting and recumbency, resting metabolic rate (MR, O2 consumption) was measured weekly and plasma was sampled for determination of glucose, total cholesterol, triglycerides, insulin, glucagon, somatostatin, growth hormone, norepinephrine, epinephrine, and cortisol in 28 burned men, 17-23 years old, TBS 2%-85%, including 8 controls with minimal injury (TBS less than or equal to 7.5%). MR was elevated in proportion to burn size mainly in the first week then declined toward normal. Growth hormone was not changed. Two multiple regression analyses (validated by random partitioning of data) determined which plasma variables independently reflected residual variation in MR: without TBS entered as a variable, high MR was associated with elevated glucose, cortisol, and glucagon, and low cholesterol (cumulative r2 = 0.79); with TBS entered, high MR was associated with greater TBS, elevated norepinephrine, and again high glucagon and low cholesterol (r2 = 0.81). Resting metabolism after burn injury is controlled not by the thyroid but may be controlled by a set of antiinsulin hormones that does not include growth hormone, but possibly includes glucagon.

Thermoregulatory and nonthermoregulatory heat production in burned rat.

Severely burned patients are hypermetabolic within their thermoneutral zone (TNZ), where there are no thermoregulatory demands on heat production. The rat has been used as a model of postburn hypermetabolism without clear evidence that it behaves in a similar way. Male rats (400-500 g; n = 34-39) were placed as a group in a respiration chamber and metabolic rates for the average rat were determined over 3-6 h at ambient temperatures between 9 and 36 degrees C. Colonic temperatures (Tco) and body weights were measured after each run. Animals were studied sequentially as normals (N), after clipping (C) and following 50% total body surface scald burns. Clipping increased the lower critical temperature (LCT) from 27.7 to 29.1 degrees C without affecting resting heat production (N = 42.6 +/- 0.5; C = 42.0 +/- 0.8 W/m2; mean +/- S.E.) or Tco (N = 36.6 +/- 0.1; C = 36.6 +/- 0.1 degrees C) in the TNZ. Injury increased LCT to 32.8 degrees C and the burned animals were hypermetabolic (47.2 +/- 0.6 W/m2; P less than 0.05 vs. N) and febrile (36.9 +/- 0.1 degrees C; P less than 0.05 vs. N) in the elevated TNZ. These metabolic and temperature responses of burned rats are limited in magnitude but are qualitatively similar to those of patients. The extra heat production in the TNZ reflects the basic metabolic cost of injury.

Ventilation-perfusion alterations after smoke inhalation injury in an ovine model.

To study the pathophysiological mechanism of progressive hypoxemia after smoke inhalation injury, alterations in ventilation-perfusion ratio (VA/Q) were studied in an ovine model by using the multiple inert gas elimination technique. Because ethane was detected in expired gas of some sheep, we replaced ethane with krypton, which was a unique application of the multiple inert gas elimination technique when one of the experimental gases is present in the inspirate. Severity-related changes were studied 24 h after injury in control and mild, moderate, and severe inhalation injury groups. Time-related changes were studied in controls and sheep with moderate injury at 6, 12, 24, and 72 h. Arterial PO2 decreased progressively with severity of injury as well as with time. In smoke-exposed animals, blood flow was recruited to low VA/Q compartment (0 < VA/Q < 0.1; 17.6 +/- 10.6% of cardiac output, 24 h, moderate injury) from normal VA/Q compartment (0.1 < VA/Q < 10). However, increases in true shunt (VA/Q = 0; 5.6 +/- 2.5%, 24 h, moderate injury) and dead space were not consistent findings. The VA/Q patterns suggest the primary change in smoke inhalation injury to be a disturbance of ventilation.

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.

Association of burn mortality and bacteremia. A 25-year review.

The relationship between bacteremia and mortality was studied in 5882 burn patients consecutively admitted to one burn center between 1959 and 1983. Among 5877 patients with adequate data, 1481 had one or more positive blood cultures; 1529 patients died. A predictor of mortality was developed, based on data from the 4396 patients without positive blood cultures, and used to assign a discrete probability of death in the absence of bacteremia to all the patients. Comparisons were then made between observed and predicted mortality in subsets of patients with bacteremia due to enteric organisms, Pseudomonas species, gram-positive organisms, or yeastlike organisms, or without bacteremia. These comparisons indicate significantly increased mortality in patients with gram-negative bacteremia, an equivocal increase in patients with blood cultures positive for yeastlike organisms, and no increase attributable to gram-positive bacteremia.

Experimental Proteus mirabilis burn surface infection.

We established a human burn isolate of Proteus mirabilis as an experimental pathogen. Infliction of a nonfatal scald injury (30%) rendered rats highly susceptible to lethal surface infection with this isolate. Dose-response experiments indicated that the lethal inoculation dose (50%) was less than 10(3) organisms per square centimeter. Histopathologically, surface colonization was followed by progressive growth with subsequent invasion of viable tissue. The invasion was not characterized by the perivascular or perineural lesions observed in experimental Pseudomonas burn sepsis. Bacteriologic examinations showed moribund animals to be bacteremic with the test strain and to have wound biopsy counts exceeding 10(6) organisms per gram of tissue. The role of bacterial motility as a virulence factor in this surface infection was investigated. Substrains selected for loss of subsurface spreading in soft agar lost virulence. This model of burn infection with a member of the Enterobacteriaceae should be used to evaluate topical and parenteral antimicrobial agents needed for the control of wound infections caused by such agents.

Mechanisms of in vitro sensitivity to sulfadiazine silver.

Sulfonamide-resistant organisms have been reported as a frequent consequence of the clinical use of sulfadiazine silver. At this burn center, sulfonamide resistance occurred in more than 80% of gram-negative isolates. We tested the requirement for the individual antimicrobial activities of sulfadiazine and silver for the vitro activity of sulfadiazine silver. The sulfadiazine component is not necessary for in vitro sensitivity. In vitro sensitivity to sulfadiazine silver does not consistently predict the presence of therapeutic activity in Pseudomonas aeruginosa-infected rats with burns. We describe an example of a transferable multiple-antibiotic resistance plasmid that contains selectable sulfonamide resistance. The use of sulfadiazine silver can, therefore, lead to the selection of organisms that are resistant not only to sulfonamides but to antibiotics of clinical consequence, and this possible risk must be considered in electing to use the agent.

Topical chlorhexidine diphosphanilate (WP-973) in burn wound sepsis.

We studied the diphosphanilate salt of chlorhexidine (WP-973), as a 2% cream, for therapeutic activity in two rat models of fatal burn wound infection. Control treatments were infection and placebo cream; infection only; infection and 1% sulfadiazine silver; and burning only. Activity against Pseudomonas aeruginosa or Proteus mirabilis was tested in surface-inoculated rats with 20% scalds. Treatments were initiated 24 hours or four hours, respectively, after inoculation. Pseudomonas-infected rats were treated once a day for ten days. Proteus-infected rats were treated once a day for five days. In these experimental models, chlorhexidine diphosphanilate was equal to silver sulfadiazine, an established topical chemotherapeutic agent. In vitro activity was examined using bacteremia isolates from 65 burned patients. Using agar diffusion trench plates, chlorhexidine diphosphanilate was active against all strains. No evidence of cross-resistance between sulfonamide and chlorhexidine diphosphanilate or its components was observed.

Lymphocyte phenotype and function changes in burn patients after intravenous IgG therapy.

The effects of prophylactic administration of intravenous IgG on immune-cell phenotype and function in burn patients were compared with those of patients receiving standard therapy. Intravenous IgG infusions were given twice weekly for three weeks postburn or until wound closure. Intravenous IgG had no effect on the proportion of total T-lymphocytes, T-helper lymphocytes, or T-suppressor lymphocytes, but the proportion of B-lymphocytes decreased 40% in treated patient samples. Lymphocytes from treated patients incorporated less thymidine when stimulated with concanavalin A or pokeweed mitogen, but not with phytohemagglutinin. The amount of IgM secreted by pokeweed mitogen-stimulated cultures from treated patients increased by 24%, while the amount of IgG remained constant. The changes in beta-lymphocyte number and functional response may have been induced by the increased serum IgG levels in the intravenous IgG-treated patients.