Fred T. Caldwell

The effect of occlusive dressings on the energy metabolism of severely burned children.

Metabolic studies were performed on 23 burned children. They were studied sequentially until their burn wounds were healed. A metabolic study lasted 20 minutes, during which continuous measurements were made of O2 consumption and CO2 production rates, rectal temperature, average surface temperatures (dressings, skin and wound), body heat content, and rate of body weight loss using a bed scale. These measurements allowed solution of the heat balance equation for each study period. After 24 hours in a constant temperature room kept at 28 C and 40% relative humidity, metabolic studies were initiated when blood was drawn for catecholamine assay, followed by a metabolic analyses, after which dressings were removed and fresh silvadene applied to the wounds. No dressings were applied. Metabolic analyses were repeated after two and four hours of exposure, after which blood for catecholamine analysis was drawn and the study terminated. Without dressings in a thermally neutral environment, burn patients demonstrated an increased rate of heat loss of 27 watts/square meter body surface area (W/M2), compared with the predicted normal. The major portion of this increment is by evaporation, which increased 300%. The rate of heat production equals heat loss, and is increased 50% above the predicted normal. Occlusive dressings result in a 15 W/M2 decrease in the rate of heat loss, about evenly divided between evaporative and dry routes, with a corresponding 15 W/M2 decrease in the rate of heat production. Plasma catecholamine levels of bandaged burn patients are not significantly different from values for healed burn patients, and do not correlate with the rate of heat production. The increased heat production of burn patients is a response to an increased rate of heat loss, not vice versa. The use of occlusive dressings substantially reduces the energy requirements to manageable levels, even in patients with very large burns.

Critical evaluation of hypertonic and hypotonic solutions to resuscitate severely burned children: a prospective study.

Children with thermal burns covering 30% or more of the body surface area were alternately resuscitated with either hypertonic lactated saline (HLS) or lactated Ringers solution (LRS). Parameters sequentially measured and calculated included: 1) serum and urine electrolyte concentrations, 2) serum and urine osmolalities, 3) arterial blood gases, 4) total and fractional serum proteins, 5) blood urea nitrogen, complete blood count and blood sugar concentration, 6) changes in body weight, 7) sodium, potassium and water balance. The water load received by the HLS group was significantly less through 48 hours postburn (49% at 8 hours, 44% at 24 hours and 38% at 48 hours postburn). Although the HLS group received significantly more sodium than the LRS group, there was no difference in sodium balance at 48 hours postburn. This is explained by the fact that the HLS group, at 48 hours postburn, retained significantly less of the administered sodium load (69% vs. 83%). Positive water balance was significantly greater in the LR group for the first 48 hours postburn. This study suggests that current hypotonic fluid regimens for burn resuscitation contain water in excess of that required for proper resuscitation. Severely burned children may be safely and efficiently resuscitated with conventional salt loads and one-third less than usual water loads.

Problems of colostomy closure

The liberal use of the colostomy, beginning in World War II, was the greatest single factor in reducing the mortality of colon and rectal injuries [I]. From such experience, temporary colostomy has become an essential part of the treatment of many emergent and some elective colon conditions. Thus, colostomy closure is now a common procedure. Despite this universal adoption and the seemingly low risk of the procedure, colostomy closure results in a significant morbidity (10 to 50 per cent) and occasional mortality (0.5 to 1 per cent). Initially, problems associated with colostomies and their closure were accepted as a matter of course. Recently, the surgical literature has included recommendations designed to reduce the morbidity of colostomy closure. Some authors have suggested that colostomy be avoided under certain conditions when it would normally be done [z]. To identify factors that contribute to the high morbidity of colostomy closure, a retrospective study of our experience was performed. Specific aims of the study included: (1) identification of problems related to colostomy closure; (2) correlation of complications with factors related to the colostomy and its management; and (3) formulation of an approach to the handling of colostomy closure.

Surgical injury of the common bile duct

Review of our experience with twenty-two bile duct injuries and the literature leads us to the following conclusions: (1) Most biliary strictures follow surgery and can be avoided by adequate exposure, accurate dissection, use of hemostatic clips rather than clamps and ties, and the liberal use of operative cholangiography. (2) Injuries diagnosed at the time of surgery should be repaired by end-to-end anastomosis over a T tube if length is adequate or by Roux-en-Y choledochojejunostomy if length is inadequate. (3) The diagnosis of biliary injury should be suspected when jaundice, biliary fistula, or cholangitis occur in the postoperative period. (4) IVC, PTC, ERCP, or fistulography should be used when possible to delineate the site of injury or stricture and assist in planning the operative repair. (5) Surgery should be performed as soon as the diagnosis is made and the patient is in satisfactory condition for operation. (6) Early reoperation may be necessary to establish drainage and prepare for a later definitive procedure. In some cases, definitive repair can be performed this time. (7) Most late strictures should be repaired with a choledochojejunostomy to a defunctionalized limb of jejunum when resection and primary end-to-end repair cannot be accomplished.

Hypertonic Lactated Saline Resuscitation of Severely Burned Patients Over 60 Years of Age

Twenty-six adults more than 60 years old with burns greater than or equal to 30% of the body surface area were resuscitated using hypertonic lactated saline (HLS). Hemodynamic parameters of resuscitation were measured in ten of the patients using a Swan-Ganz catheter. In spite of signs of hemodynamic stability, these patients demonstrated mean cardiac indices (CI) below their age-corrected norms and pulmonary capillary wedge pressures (PCWP) below 5 mm Hg through 24 hours, yet 92% of the patients produced normal or super-normal volumes of urine. Hemodynamic monitoring may be helpful for precise fluid replacement in extensively burned elderly patients; however, a normal CI and PCWP may not be the appropriate endpoint for resuscitation of the elderly when using HLS. This review supports the concept that HLS resuscitation of critically burned older patients is both safe and efficacious, leading to an 81% survival of this severely compromised group well past the resuscitation phase of injury.

A prospective analysis of silver sulfadiazine with and without cerium nitrate as a topical agent in the treatment of severely burned children.

Previous studies have indicated that combining cerium nitrate with silver sulfadiazine (Silvadene, Marion Labs) yields a superior topical agent for the treatment of burns. Cerium nitrate in silver sulfadiazine was tested in a controlled study with silver sulfadiazine alone. The study population consisted of two groups of children suffering burns greater than 30% of the body surface. The patients ranged in size from 1 to 21 years. The study period was for the first 10 weeks of hospitalization. Quantitative surface cultures were used to monitor burn wound flora. No superiority for the silver sulfadiazine-cerium nitrate combination was demonstrated. In fact, cultures indicate a significantly greater percentage of Gram-negative pathogens in patients treated with the cerium mixture. Cerium nitrate could possibly prove of greatest benefit if used as a reserve therapy for colonizing organisms which do not routinely respond to silver sulfadiazine.

Humoral versus neural pathways for fever production in rats after administration of lipopolysaccharide.

BACKGROUND These studies address the question of the relative roles of humoral and neural pathways in the genesis and control of the fever component of the acute phase response. METHODS Two experiments were performed to examine the effect of vagotomy (VagX) on the febrile response to intraperitoneal (i.p.) and intra-arterial (i.a.) lipopolysaccharide (LPS), and plasma cytokine and LPS concentrations after intravenous (i.v.) or i.p. injections of LPS. In experiment 1, body temperature (T(B)) was obtained from unperturbed animals by using radio transmitters and telemetry after injection of LPS i.a. or i.p. In the second study, serial blood samples were obtained for cytokine and LPS assay after injection of LPS either i.v. or i.p. Colonic temperatures (T(C)) were obtained from indwelling thermistors. RESULTS The maximal increments in T(B) for animals receiving LPS i.a. and i.p. with or without VagX were not different from one another: sham vagotomy (Sham-VagX) + LPS i.a., 1.20 +/- 0.26 degrees C; VagX + LPS i.a., 1.23 +/- 0.64 degrees C; Sham-VagX + LPS i.p., 1.45 +/- 0.27 degrees C; VagX + LPS i.p., 1.50 +/- 0.35 degrees C (F = 1.12, p = 0.36). Neither were the four resulting response curves for T(B) different from one another. Plasma levels of LPS, tumor necrosis factor-alpha, and interleukin-6 were significantly elevated at 45 minutes after LPS injection by either the i.v. or i.p. routes, preceding any increments in T(B), and were not effected by VagX. CONCLUSION Fever development for animals receiving LPS in experiment 1 demonstrates a temporal relationship -- with increments in plasma levels of LPS and pyrogenic cytokines obtained in experiment 2 after administration of LPS either i.p. or i.v. Vagotomy had no discernible effect on the responses regardless of the route of administration of LPS.

The interrelationships between wound management, thermal stress, energy metabolism, and temperature profiles of patients with burns

This prospective randomized study was performed to evaluate the metabolic and thermal responsiveness of patients with burns to thermal stress with three protocols of wound care: group I (n = 7) treated with dressings and variable ambient temperature selected for patients subjective comfort; group II (n = 7) treated without dressings and variable ambient temperature for patient comfort; group III (n = 6) treated without dressings and ambient temperature of 25 degrees C, electromagnetic heaters were set to achieve patient subjective comfort; and group IV (n = 6) healthy volunteers. After baseline partitional calorimetry was performed, individual patients were cold-challenged while subjectively comfortable by sequentially lowering either the ambient temperature or the output from the electromagnetic heaters. Heat balance and temperatures were obtained after each perturbation in external energy support. For patients in groups I and II, subjective perception of thermal comfort (warm, neutral, neutral and fed, cool, or cold) was more strongly correlated (p < 0.02) with the changes in the rate of heat production than the actual ambient temperature. For patients treated with electromagnetic heaters, changes in heat production were most strongly correlated with the energy output from the electromagnetic heaters. Even though the environmental conditions required to achieve a particular level of comfort are quite different between treatment groups, the difference in temperature between the patients surface and ambient is approximately the same for groups I, II, and IV for each subjective state.(ABSTRACT TRUNCATED AT 250 WORDS)

Ibuprofen lowers body temperature and metabolic rate of humans with burn injury.

A group of 15 burned children and young adults with large burns (mean, 41% +/- 15% BSA) were administered ibuprofen (40 mg/kg for 3 days). Each patient served as his or her own control in this crossover study (with and without ibuprofen). Paired calorimetric and temperature studies and urinary nitrogen measurements were performed. No nitrogen-sparing effect was identified for this dose of ibuprofen. However, patients demonstrated a statistically significant reduction in average rectal temperature (0.67 degrees C decreases) (p less than 0.01) and in metabolic rate (11.4% decreases) (p less than 0.01) while taking ibuprofen. Linear regression analysis of the reduction in temperature versus the reduction in metabolic rate yielded a statistically significant correlation (p less than 0.01) with a slope of 13.6% reduction in metabolic rate per degree centigrade reduction in the 72-hour average rectal temperature. These results support the hypothesis that ibuprofen attenuates the hypermetabolic response to thermal injury by blunting the temperature elevation that is usually seen.

Manipulation of the inflammatory response to burn injury

BACKGROUND Burn injury is characterized by hypermetabolism and protein catabolism. Endotoxin, derived from either wound or gut, may participate in this response. METHODS Eleven seriously burned patients were treated with the endotoxin-binding agent polymyxin B and underwent partitional calorimetry and nitrogen balance studies. The data from theses patients were compared with data from 28 contemporary, similarly burned patients who did not receive polymyxin B. RESULTS Elevated levels of circulating endotoxin were not consistently detected in either group. Interleukin-6 was elevated and correlated with rectal temperature and nitrogen excretion in both groups. Administration of polymyxin B produced no change in metabolic rate but produced a significantly more positive nitrogen balance and was associated with a prompt reduction in interleukin-6 levels. CONCLUSIONS These data support the hypothesis that endotoxin plays a role in the postburn protein catabolism but not in the hypermetabolic response. This protein catabolic response is statistically associated with circulating interleukin-6 levels, suggesting a possible role for interleukin-6 in postinjury protein wasting.