Relationships between patient characteristics and unsuccessful substance abuse detoxification.

OBJECTIVE: History and laboratory evaluations are common for patients entering substance abuse detoxification programs. We sought to identify if patient history and laboratory characteristics entering a detoxification program were associated with unsuccessful detoxification. DESIGN: Retrospective cohort study of 186 patients of a residential-inpatient short-term medical detoxification facility. Unsuccessful detoxification was defined as leaving for urgent medical referral or against program advice. RESULTS: Patients were predominantly male, middle-aged, minority, unemployed, and poly-substance users. Twenty-four patients (13%) did not complete the detoxification program (4 left for urgent medical referral, 20 left against program advice). Unsuccessful detoxification was associated with nausea and/or vomiting (p = 0.032), Caucasian race (p = 0.002), and opiates as a drug of choice (p = 0.018). Laboratory abnormalities were common but none were associated with unsuccessful detoxification. CONCLUSIONS: For patients admitted to a medically monitored detoxification facility, few patient characteristics were associated with detoxification outcome. Routine admission laboratories without clinical correlation may be unwarranted.

Changes in the tissue and plasma superoxide dismutase (SOD) levels in a burned rat model.

To examine whether thermal injury alters the superoxide dismutase (SOD) concentrations in various types of tissue or plasma, we studied the plasma and tissue Mn- and Cu/Zn-SOD levels in a rodent burn model. The animals were resuscitated with saline (50 mg/kg, i.p.) immediately following thermal injury and thereafter were sacrificed at either 6 or 24 hours post-burn. The Mn- and Cu/Zn-SOD levels were measured using an enzyme-linked immunosorbent assay (ELISA). The plasma Mn- and Cu/Zn-SOD concentrations significantly increased 6 hours after the injury and positively correlated with the burn size. The kidney Mn-SOD concentrations were significantly higher 24 hours after the injury in the animals with 30% burns than in those with either sham or 50% burn injuries. The lung Cu/Zn-SOD concentrations were also significantly higher 6 hours after the injury in animals with 30% burns than in the other two types above. These findings suggest that the changes in the SOD concentrations after burn injury vary according to the type of SOD and also the type of tissue. As a result, the SOD concentrations may play some role in the early response to thermal trauma.

Half-life of blood carboxyhemoglobin after short-term and long-term exposure to carbon monoxide.

BACKGROUND: In models of smoke inhalation injury and carbon monoxide poisoning blood carboxy-hemoglobin (COHb) levels decrease faster than predicted by the generally recognized half-life of COHb. We studied the effects of duration of exposure to carbon monoxide (CO) on the subsequent CO elimination. METHODS: Each of four sheep were insufflated with CO gas mixtures either for a few minutes (short-term exposure) or for several hours (long-term exposure), then ventilated with air for 3 hours. Serial COHb concentrations were analyzed by using a two-compartment, single central outlet mathematical model. RESULTS: Short-term exposures exhibited biphasic decreases of COHb concentration compatible with a two-compartment model; an initial rapid decrease (half-life 5.7 +/- 1.4 minutes) was followed by a slower phase (103 +/- 20.5 minutes). Long-term exposures exhibited almost monophasic decreases, which were nevertheless compatible with the model (half-life, 21.5 +/- 2.1 and 118 +/- 11.2 minutes). CONCLUSION: This study demonstrated different patterns of CO elimination curve, which suggests distribution of CO to two compartments having different rates of equilibration.

Perceptions of pediatric emergency medicine fellows and program directors about research education.

UNLABELLED: Pediatric emergency medicine (PEM) fellows who entered training after January 1995 are required to complete three years of fellowship training. Additionally, they are required to receive instruction in related basic sciences and to demonstrate research competence. OBJECTIVES: To determine: 1) whether PEM fellows and program directors perceive their programs as providing adequate training in research principles, 2) the manner in which these principles are taught, and 3) the commitment of fellows and program directors to research and research training. METHODS: Pediatric emergency medicine fellows who participated in the Fourth Annual PEM Fellows Conference (Miami, Florida, March 1997) were surveyed. The survey was then extended via mail to all PEM fellows and program directors in the United States and Canada. RESULTS: A total of 159 of the 220 fellows (72%) in the United States and Canada returned completed questionnaires. Fifty-three of 70 PEM fellows (76%) who attended the conference completed questionnaires, and 106 of 167 fellows (63%) who did not attend the conference responded by mail. Fifty-three of the 63 program directors (84%) returned completed questionnaires. Of 159 responding fellows, 86 (54%), and of 53 responding program directors, 29 (58%) reported that their programs lacked adequate training in one or more of the surveyed research areas. Thirteen program directors (25%) reported no formal research training in their curricula. Programs that included formal research training were perceived to have higher overall quality than programs that failed to offer such formal training. Sixty-six of 158 responding fellows (42%) anticipated an ongoing commitment to research in their careers. One hundred fourteen of 153 responding fellows (75%) indicated that, if given the option, they would have pursued a two-year "clinical track" PEM board certification that did not include a research requirement. CONCLUSIONS: More than half of surveyed PEM fellows and program directors perceived important deficiencies in research education within their training programs. Further research is necessary in order to evaluate the validity of these perceptions.

Effect of Sulfo Lewis C on smoke inhalation injury in an ovine model.

OBJECTIVE: To evaluate the effect of Sulfo Lewis C (SO3-3âGal1-3GlcNAc-O(CH2)8-COOMe), a putative ligand of selectins, on smoke inhalation injury. DESIGN: Prospective animal study with concurrent controls. SETTING: An animal laboratory. SUBJECTS: Twelve 1-yr-old female sheep, weighing 24 to 33 kg. INTERVENTIONS: Twelve sheep received nine exposure units of smoke generated by thermolysis of pine woodchips (80 g). Group 1 (n = 6) was untreated. Group 2 (n = 6) was treated with an intravenous infusion of Sulfo Lewis C after smoke exposure. Animals were killed 48 hrs after injury. MEASUREMENTS AND MAIN RESULTS: Cardiopulmonary variables and blood gases were measured serially. Granulocyte free-radical production was measured before smoke exposure and at 4 and 48 hrs after injury. Ventilation/perfusion distribution (VA/Q) was analyzed using the multiple inert gas elimination technique. Granulocyte free-radical production was increased after smoke exposure in both groups. Oxygenation was significantly improved by the administration of Sulfo Lewis C. VA/Q analysis demonstrated significantly less blood flow to low VA/Q lung segments in treated animals. CONCLUSIONS: Selectin blockade attenuated lung injury after smoke exposure. These data support the hypothesis that neutrophils play a pivotal role in smoke inhalation 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.

Direct current reduces plasma protein extravasation after partial-thickness burn injury in rats.

OBJECTIVE: To observe the effect of 40 microA direct current (DC) on plasma albumin extravasation after burn injury. DESIGN, MATERIALS, AND METHODS: Silver-nylon wound dressings were used as anodes (-) on anesthetized male Sprague-Dawley rats with 20% total body surface partial-thickness scald burns. Burned rats with no treatment, or treated with silver-nylon dressing without current, were used as controls. Quantitative analysis of fluorescein isothiocyanate (FITC)-albumin leakage and accumulation in the wound tissue was performed using confocal fluorescence microscopy. MEASUREMENTS AND MAIN RESULTS: In controls, the rate of albumin leakage was maximal at 1 hour postburn (PB) and then decreased, but remained higher than normal for 48 hours PB. The accumulation of FITC-albumin was maximal 4 to 6 hours PB and substantial for 48 hours. When DC was applied, leakage was reduced by 30 to 45% and approached normal control rates by 8 hours PB. FITC-albumin concentration peaked 4 hours PB, was 18 to 48% less then in burned control, and approached the level observed in unburned control by 18 hours PB. CONCLUSIONS: DC has a beneficial effect in reducing plasma protein extravasation after burn injury.

Direct current reduces wound edema after full-thickness burn injury in rats.

OBJECTIVE: To observe the effect of 4 and 40 microA direct current (DC) on edema formation after burn injury in rats. DESIGN, MATERIALS, AND METHODS: Silver-nylon wound dressings were used as either anodes (-) or cathodes (+) on 20% total body surface area full-thickness scalds in anesthetized male Sprague-Dawley rats. Untreated burned rats and rats treated with silver-nylon dressings without current were used as controls. MEASUREMENTS AND MAIN RESULTS: Immediately applied, continuous DC reduced burn edema by 17 to 48% at different times up to 48 hours postburn (p < 0.001). Neither reversal of electrode polarity nor change in current density had any significant effect on the results of treatment. Starting treatment during the first 8 hours postburn produced the least edema accumulation, but the reduction was significant even when DC was applied 36 hours afterburn. If started immediately after injury, treatment had to be continued a minimum of 8 hours to be most effective. CONCLUSIONS: Direct electric current has a beneficial effect in reducing wound edema after burn injury.

Effect of ambient temperature on metabolic rate after thermal injury.

OBJECTIVE: The authors describe the effect of ambient temperature on metabolic rate after thermal injury. SUMMARY BACKGROUND DATA: Thermal injury induces a hypermetabolic state, which is reported to increase with the extent of burn. The magnitude of this response is further influenced by ambient temperature. METHODS: The resting energy expenditure was measured by indirect calorimetry at ambient temperatures of 22, 28, 32, and 35 C. It was indexed to a calculated basal metabolic rate in normal volunteers and adult patients with burns involving at least 20% of the total body surface area who had no evidence of systemic infection. These measurements were performed between postburn days 6 and 21. RESULTS: The effect of ambient temperature on metabolic rate was measured in 44 burn patients and 8 normal volunteers. Burn size ranged from 20 to 97% total body surface area with a mean of 44 +/- 18.5% total body surface area. Metabolic rate did not change significantly in control subjects as ambient temperature was varied (p<0.05). Regression analysis showed that burn size and ambient temperature were significant determinants (p<0.01) of metabolic rate in the patients and that together these factors accounted for 55% of the variation observed (df adj. r(2)=0.55) across the range of ambient temperatures studied. Metabolic rate was independent of burn size at ambient temperatures of 32 and 35 C (p<0.02) and increased by a factor of 1.5 X basal metabolic rate. A further increase in metabolic rate, which was positively correlated with burn size, resulted from nonshivering thermogenesis at ambient temperatures 28 and 22 C. The magnitude of this response was greatest at 22 C. CONCLUSIONS: These findings suggest that the hypermetabolic response to thermal injury is maximal in burns as small as 20% total body surface area and that an additional burn size-dependent increase in metabolic rate results from heat loss at ambient temperatures below thermoneutrality.

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.

Enhanced survival of autoepidermal-allodermal composite grafts in allosensitized animals by use of silver-nylon dressings and direct current.

OBJECTIVE: Observe the effect of silver-nylon (SN) dressing and direct electric current on healing of meshed autoepidermal/allodermal composite skin grafts (MCSGs) in allosensitized rats. MATERIALS AND METHODS: MCSGs were placed on experimental animals 28 to 30 days after placement of sensitizing allografts. MCSGs and control allografts were covered with either Vaseline gauze (VG) or SN; direct current, 40 microA, was applied for 5 days to some of the SN-dressed wounds (SNDCs). MEASUREMENTS AND MAIN RESULTS: Second set rejection of MCSG was not observed. SN- and SNDC-treated grafts showed expansion of the meshed autoepidermis with complete epithelialization within 3 weeks. VG-covered wounds developed areas of open granulation and were not completely epithelialized at 3 months. Both SN and SNDC reduced wound contraction when compared to VG (SN versus VG p < 0.02, SNDC versus VG p < 0.008). MCSG was found to be of low alloantigenicity in that it did not induce second set rejection of subsequent skin allograft. CONCLUSIONS: SN dressings enhanced survival of meshed composite skin grafts.

The risk of pneumonia in thermally injured patients requiring ventilatory support.

The risk of pulmonary infectious complications in critically ill patients requiring ventilatory support is well established. To evaluate the impact of tracheal intubation on the risk of pneumonia, the records of three hundred seventy thermally injured patients (mean age, 37.6 years, mean total body surface area burn, 44.7%) who were admitted during a 6-year interval and required ventilatory support were reviewed. The mean duration of intubation in these patients was 16.6 days, the incidence of pneumonia was 50%, and observed mortality was 37% (137 patients). Though they were significantly older (42.7 vs 35.6 years, p = 0.005) and had a higher frequency of pneumonia (60% vs 46%, p = 0.015) than the 265 patients with inhalation injury, the 105 patients without documented inhalation injury had mean burn size (41.9% vs 45.9%), length of intubation (18.9 vs 15.7 days), postburn day of pneumonia (12.7 vs 10.5 days), and mortality (38.1% vs 36.6%) similar to that group. Actuarial life table analysis considering only pneumonia acquired during ventilatory support was used to evaluate the relation between the risk of pneumonia and duration of ventilatory support. In this cohort of patients with burns, no difference in the risk of pneumonia was observed between patients with and without inhalation injury who required ventilatory support; the hazard of pneumonia was relatively constant during the first 6 weeks of intubation and was similar for all who underwent ventilation.

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.

The effect of inhaled nitric oxide on pulmonary ventilation-perfusion matching following smoke inhalation injury.

BACKGROUND: We previously reported that inhaled nitric oxide (NO) improved pulmonary function following smoke inhalation. This study evaluates the physiologic mechanism by which inhaled NO improves pulmonary function in an ovine model. METHODS: Forty-eight hours following wood smoke exposure to produce a moderate inhalation injury, 12 animals were anesthetized and mechanically ventilated (FIO2, 0.40; tidal volume, 15 mL/kg; PEEP, 5 cm H2O) for 3 hours. For the first and third hours, each animal was ventilated without NO: for the second hour, all animals were ventilated with 40 ppm NO. Cardiopulmonary variables and blood gases were measured every 30 minutes. The multiple inert gas elimination technique (MIGET) was performed during the latter 30 minutes of each hour. The data were analyzed by ANOVA. RESULTS: Pulmonary arterial hypertension and hypoxemia following smoke inhalation were significantly attenuated by inhaled NO compared with the values without NO (p < 0.05, ANOVA). Smoke inhalation resulted in a significant increase in blood flow distribution to low VA/Q areas (VA/Q < 0.10) with increased VA/Q dispersion. These changes were only partially attenuated by the use of inhaled NO. The SF6 (sulfur hexafluoride) retention ratio was also decreased by inhaled NO. Peak inspiratory pressures and pulmonary resistance values were not affected by inhaled NO. CONCLUSIONS: Inhaled NO moderately improved VA/Q mismatching following smoke inhalation by causing selective pulmonary vasodilation of ventilated areas in the absence of bronchodilation. This modest effect appears to be limited by the severe inflammatory changes that occur as a consequence of smoke exposure.

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.

A longitudinal study of resting energy expenditure in thermally injured patients.

We have recently developed a new burn-specific equation that satisfactorily estimates initial caloric requirements for thermally injured patients. In the present study, we compared these estimates with resting energy expenditures (REE) (n = 141) measured weekly by indirect calorimetry in 20 patients between postburn days 3 and 348. In this group, mean initial burn size was 46.7% (range, 21-88) and mean age 31.3 years (range, 19-61). Serial measurements were continued until the burn wounds were closed or the patient was discharged. Multiple regression analysis indicated a relationship between REE, initial burn size, and postburn day in these patients (r = 0.65). This analysis indicated a general trend of decline in REE toward normal values 100 to 150 days postburn in patients with smaller burns (20%-40%) and roughly 250 days postinjury in those with larger burns (> 75%). The initial predictive equation appeared adequate for estimating caloric needs during the first postburn month, but beyond 30 days postburn indirect calorimetric measurements became necessary for accurate estimation of caloric requirements.

The effect of inhaled nitric oxide on smoke inhalation injury in an ovine model.

Smoke inhalation is a significant comorbid factor in thermal trauma. The effect of inhaled nitric oxide (NO) on smoke inhalation injury was evaluated in an ovine model. Following smoke exposure, group 1 animals (n = 9) spontaneously breathed room air, and group 2 animals (n = 8) breathed 20 parts per million of NO in air for 48 hours. Cardiopulmonary variables and blood gases were serially measured; bronchoalveolar lavage (BAL) was performed and wet-to-dry lung weight ratios (W/D) determined at 48 hours. Pulmonary vasoconstriction following smoke inhalation was significantly attenuated by inhaled NO (p < 0.05), which exerted no apparent effect on the systemic circulation. In group 2, the serial decline in pulmonary oxygenation was less than in group 1, consistent with a smaller physiologic shunt (p < 0.05). There were no significant differences in W/D, lung compliance, BAL fluid analysis results, or histologic evaluation findings between the two groups. These results suggest that inhaled NO exerted beneficial effects on pulmonary arterial hypertension and oxygenation following smoke inhalation without apparent amelioration of airway inflammation.

Comparison of acid neutralizing and non-acid neutralizing stress ulcer prophylaxis in thermally injured patients.

We have compared the effectiveness of non-acid neutralizing stress ulcer prophylaxis (SUC) with sucralfate (n = 48) with that of acid neutralizing prophylaxis (AN) utilizing antacids and cimetidine (n = 48) in the prevention of stress ulcer bleeding and nosocomial pneumonia (PN) in thermally injured patients. In the subset of intubated patients, the incidence of PN was 17.8% and 42.8% in the AN and SUC groups, respectively (p < 0.05) despite a similar postburn time of onset of pneumonia. Ten patients in each group died. Three patients in the SUC group developed upper GI bleeding with one requiring gastrectomy. Bacterial colonization of the upper airway occurred in virtually all patients, whereas 83% (SUC) and 96% (AN) had colonization of gastric contents. Gram-negative colonization rates for the upper airway were not different (70%) whereas 48% of SUC patients compared with 60% of AN patients had gram-negative gastric colonization. In conclusion, SUC therapy was efficacious in the prevention of stress ulcer bleeding but did not alter the rate of bacterial colonization of the airway or gastric contents, and was associated with a higher incidence of nosocomial pneumonia in intubated patients.