Biomedical subjects
B A Pruitt
Publications and source records attributed to B A Pruitt.
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.
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.
Effect of prostaglandin E in multiple experimental models. VI. Effect on T-cell subsets.
Burn injuries have been shown to impair immune function. One of the hypotheses for the etiology of the immunosuppression is that burn injuries result in an elevation of prostaglandin E (PGE) levels which then impair leukocyte function. We evaluated the effect of PGE levels on immune function in multiple animal models utilizing T cell subset levels for our immunologic measurements. Elevations in PGE levels were achieved by administering 16,16-dimethyl-prostaglandin E (dPGE) and reductions by administering indomethacin. The animal models included burned rats, burned-septic rats, and nonburned rats. Neither indomethacin nor dPGE administration resulted in alterations of any of the T cell subset populations in our models.
High-frequency percussive ventilation in patients with inhalation injury.
Inhalation injury complicated by bacterial pneumonia is now one of the primary causes of morbidity and mortality in patients with thermal injury. We have investigated the use of high-frequency percussive ventilation (HFPV) as a means of ventilatory support for these patients. We propose that high-frequency ventilation may decrease the incidence of pulmonary infection following inhalation injury and decrease the incidence of iatrogenic barotrauma caused by conventional ventilation. High-frequency ventilation was instituted initially as salvage therapy in a group of five patients. In each case, normocapnia or arterial pO2 saturation of greater than 90% on a FIO2 of 60% or less was achieved with high-frequency ventilation but not with conventional ventilation. A second group of ten patients was prospectively entered into a study on the use of HFPV in patients with inhalation injury. One patient was removed from the study, and one patient was unable to be ventilated because of severely noncompliant lungs. Eight patients with a mean age of 29 years and a mean burn size of 38% of the total body surface completed the protocol. All patients survived, two developed pneumonia, and one developed subcutaneous emphysema. These results suggest that HFPV is effective in the treatment of patients with severe inhalation injury.
Relationship of transfusion and infection in a burn population.
The relationship between the number of red blood cell transfusions and major infectious complications was evaluated in 594 thermal injury patients admitted between 1982 and 1986 who had burns over 10% or more of total body surface area and survived more than 10 days. The mean age of this group was 32.9 years, with a mean burn size of 36% of total body surface area; 83% were male. Of the 594 patients, 23.7% died and 38.7% had documented inhalation injury. The mean number of red blood cell transfusions received was 19.7, with a range of 0 to 201. Two hundred fourteen patients (36%) had major infectious complications, defined as pneumonia or invasive burn wound infection. A cross-tabulation of predicted mortality, number of transfusions, and infectious complications revealed a significant positive correlation between transfusion number and infectious complications in patients with predicted mortalities between 10 and 70%. Per cent total burn, patient age, presence of inhalation injury, and number of transfusions were identified by discriminant function analysis as significant variables (p less than 0.05) in discriminating between patients with and without infections (85% accuracy). Logistic regression analysis confirmed the above findings, showing a relationship between the number of transfusions received and infectious morbidity which was independent of age or burn size, but no significant relationship between number of transfusions and mortality.
[Application of a gas chromatography-mass spectrometer (GC-MS) to the multiple inert gas elimination technique: multiple inert gas measurement with a GC-MS at trace level].
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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.
The pathogenesis of multiple organ failure.
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Lymphoid subpopulation changes after thermal injury and thermal injury with infection in an experimental model.
Subpopulation analysis of peripheral blood lymphocytes is a frequently used measure of immunocompetence. Yet, little is known about the lymphocyte subpopulations in the circulation and lymphoid organs after severe trauma. Blood, spleen, and lymph node (LN) subpopulations were compared in a rat model of burn injury (B) and burn injury with infection (BI). B and BI rats received 30% total body surface scald burns. Infection was induced by seeding wounds with Pseudomonas aeruginosa. Subpopulations were identified by flow cytometry 48 hours after burn. Helper lymphocytes were selectively depleted from the circulation of BI but not B animals, which caused the ratio of helper to suppressor cells (HSR) in BI animals to decrease significantly compared with the unburned controls. Both LN helper and suppressor cells were decreased in BI animals and the HSR was unchanged, but a selective reduction in suppressor cells in B LN increased the HSR relative to unburned controls. Spleen subpopulations were unchanged for both B and BI groups. Subpopulation changes after trauma and infection were different for each tissue examined.
Chemical burns.
In chemical skin injuries, reduction of the time of exposure to the causative agent and recognition of systemic toxicity are necessary to lessen the severity of the insult, reduce morbidity, and maximize survival. During a 17-year period (1969 through 1985), 87 (2.1%) of the 4,212 burned patients admitted to the U.S. Army Institute of Surgical Research sustained chemical burns. Twelve of 87 patients died (13.8%). White phosphorous, the most common causative agent, produced cutaneous injury in 49 patients. Acids (13 patients), alkalies (ten patients), and organic solvents (five patients) were the other common causes of injury. Initial treatment consisted of water lavage. Later wound management was carried out with topical antibiotic therapy and excision and grafting as necessary. Systemic toxicity due to phenol, nitrate, and formate absorption occurred, as did acute tubular necrosis following copper sulfate treatment of white phosphorus burns. Inhalation injury occurred in five patients. A decrease in hospital stay for chemically injured patients was observed. To minimize chemical injury, clothing should be removed promptly and water lavage begun. Systemic toxicity and inhalation injury are rare but often severe and increase mortality.
Heterotopic bone formation in burned patients.
Heterotopic bone formation about joints and in soft tissues is known to cause joint immobilization and permanent physical impairment in burned patients. Despite aggressive physical therapy aimed at prevention, heterotopic bone formation still occurs in a small percentage of patients. Prolonged immobilization in concert with trauma or burn about the involved joint is recognized as being responsible for this heterotopic bone formation. Specifically, immobilization of extremities, particularly the elbow and upper extremity, should be minimized by early grafting for preservation of function. As burn therapy has enabled increasing numbers of patients to survive extensive burns, it is imperative that preservation of function not be ignored and that attention be directed at improved function early in the postburn course.
Therapeutic effects of silver nylon dressings with weak direct current on Pseudomonas aeruginosa-infected burn wounds.
The therapeutic and prophylactic effects of nylon dressings coated with metallic silver in a direct current circuit have been examined in a rat model of fatal burn wound sepsis. Male Sprague-Dawley rats weighing 325 +/- 25 grams with 20% full-thickness scald injuries were used. Therapeutic effects were examined at 4 or 24 hours after surface inoculation with a lethal dose of Pseudomonas aeruginosa (Strain 59-1244). When used as a surface anode with an implanted silver needle cathode, the silver nylon was therapeutic at currents between 0.4 and 40 microA when applied at either test time and continued for 5 days (p less than 0.001). When used as a cathode, silver nylon was not effective. Nylon cloth without a silver metal coating was not effective without applied current or when used as an anode. Silver nylon dressings placed at 4 hours after inoculation but without applied current showed significant effectiveness (p less than 0.01). This effect, however, was significantly less than that seen with silver nylon used as an anode (p less than 0.001). Barrier prophylactic effects were examined by placing silver nylon or uncoated nylon on burn wounds before inoculation with Pseudomonas aeruginosa. The uncoated nylon had no barrier effect. Silver nylon was found protective but applied current was not required for significant (p less than 0.001) barrier effect. These results indicate silver nylon dressings may be a valuable antimicrobial burn wound covering device.
Fluid resuscitation of infants and children with massive thermal injury.
Age-related limitations of physiologic reserve in burned children make adequacy of intravenous fluid resuscitation critical. To quantify fluid requirements, the medical records of all children admitted to the Army Institute of Surgical Research from 1980 to 1986 whose weight was 25 kilograms or less and burn size was 25% or greater were reviewed to quantify fluid requirements. Forty-three children ranging in age from 1.5-108 months (means 26 +/- 22 m), with 25-89% total body surface burned (TBSB) (means 41.7% +/- 14.6%), met inclusion criteria. The average total volume of fluid received during the first 24 hours was 6.3 +/- 2.2 cc/kg/% TBSB. The net volume of resuscitation fluid, total volume less the calculated maintenance fluid requirements, was 3.91 +/- 2.2 cc/kg/% TBSB. Univariate analysis and linear regression of independent variables including age, weight, per cent full thickness, and inhalation injury revealed each had no significant influence on the volume of resuscitation. We recommend supplying maintenance volume and initiating burn resuscitation at 3 cc/kg/% TBSB.
Smoke inhalation injury in sheep.
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A method of estimating the extensiveness of lesions (burns and scalds) based on surface area proportions.
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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.
Burn treatment for the unburned.
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