Comparison of a supra-sternal cardiac output monitor (USCOM) with the pulmonary artery catheter.

BACKGROUND: Cardiac output (CO) cannot reliably be estimated by clinical examination. We aimed to measure the agreement between CO measurements using a supra-sternal Doppler monitor (USCOM, Coffs Harbour, Australia) and the pulmonary artery catheter (PAC). METHODS: The study was conducted in the intensive care unit of a tertiary teaching hospital. All patients with PAC in situ were eligible. Simultaneous CO readings were taken when clinically indicated. Investigators and clinicians were blinded to each other's results. The CO values used were the mean of three consecutive supra-sternal Doppler readings for patients with a sinus rhythm and seven for atrial fibrillation, and the mean of three thermodilution curves with acceptable form and values within 10% of each other for the PAC. Agreement was measured using both the paired t-test to calculate bias and limits of agreement and the intraclass correlation (ICC) coefficient. RESULTS: Ninety-four subjects were enrolled. From 89 subjects, 250 paired comparisons were obtained. USCOM monitor readings were unobtainable in five patients. Mean supra-sternal Doppler CO was 5.5 litre min(-1). Bias was -0.09 litre min(-1) and levels of agreement were +/- 2.92 litre min(-1) when compared with PAC. ICC was 0.46 (95% CI 0.36-0.56), and mean percentage difference was 19 (IQR 6-31)%. CONCLUSIONS: In our subjects, there was poor agreement between CO measurements done with the supra-sternal Doppler monitor and PAC.

Thermal inactivation D- and Z-values of Salmonella and Listeria innocua in fully cooked and vacuum packaged chicken breast meat during postcook heat treatment.

Studies were conducted to determine thermal inactivation D- and z-values of Salmonella and Listeria innocua in fully cooked and vacuum-packaged chicken breast meat. Fully cooked chicken breast meat products that were obtained from three different sources with differing formulations were uniformly inoculated with a cocktail of Salmonella (including Senftenberg, Typhimurium, Heidelberg, Mission, Montevideo, and California) or L. innocua at approximately 10(7) cfu/g. The inoculated meat samples were vacuum-packaged and then heat-treated at a temperature of 55 to 70 C for 5 to 90 min. After heat treatment, the samples were immediately cooled in an ice-water bath. Survivors of Salmonella and L. innocua were enumerated for each sample. D- and z-values of Salmonella and L. innocua were determined for each product and compared among the products. Source and formulation did not cause significant differences in the D- and z-values of Salmonella or L. innocua among the three fully cooked and vacuum-packaged chicken breast meat products.

Ultrasonography by emergency physicians in patients with suspected cholecystitis.

This article investigates the use of bedside abdominal ultrasonography (BAU) performed by emergency physicians (EPs) to screen patients for cholelithiasis and cholecystitis. In this prospective study EPs performed BAU on 116 patients. Agreement between BAU and formal abdominal ultrasound (FUS) performed in the radiology department for detecting cholelithiasis and cholecystitis was determined using Kappa statistics. Test characteristics of BAU for detecting cholelithiasis and acute cholecystitis were calculated. Agreement between BAU and FUS was 0.71 for cholelithiasis and 0.46 for acute cholecystitis. Test characteristics of BAU for cholelithiasis were sensitivity 92%, specificity 78%, positive predictive value (PPV) 86%, negative predictive value (NPV) 88%. Test characteristics of BAU for acute cholecystitis compared with clinical follow-up were sensitivity 91%, specificity 66%, PPV 70%, NPV 90%. BAU may be used to exclude cholelithiasis and is sensitive for cholecystitis. However, when EPs with limited experience identify cholecystitis a confirmatory test is warranted before cholecystectomy.

Thermal lethality of Salmonella Senftenberg and Listeria innocua in fully cooked and packaged chicken breast strips via steam pasteurization.

Fully cooked chicken breast strips were surface inoculated to contain 9 log10 (CFU/g) Salmonella Senftenberg or Listeria innocua. The inoculated products were vacuum packaged in 0.2-mm-thick barrier bags (241 by 114 mm), then steam pasteurized at 88 degrees C in a continuous process for 26 to 40 min or in a batch process for 33 to 41 min. After the treatments, the products were analyzed for the survivors of Salmonella or Listeria. The models were developed to correlate the surviving rate of Salmonella and Listeria with cooking time for both continuous and batch processes. A cooking time of 34 min was needed to achieve 7 logs of the reduction in a batch process. To achieve the same log reduction, a longer (6 min) cooking time was needed in a batch process than in a continuous process. The results from this study will be useful for processors to evaluate postcooking treatment procedures for ready-to-eat meat products.

Repeated exposure of rats to JP-4 vapor induces changes in neurobehavioral capacity and 5-HT/5-HIAA levels.

Thirty-two Sprague-Dawley rats were exposed for 6 h/d for 14 consecutive days to JP-4 jet fuel vapor (2 mg/L) or room air control conditions. Following a 14- or 60-d recovery period, rats completed a battery of 8 tests selected from the Navy Neurobehavioral Toxicity Assessment Battery (NTAB) to evaluate changes in performance capacity. Exposure to JP-4 vapor resulted in significant changes in neurobehavioral capacity on several tests that varied as a function of the duration of the recovery period. Rats were evaluated for major neurotransmitter and metabolite levels in five brain regions and in the blood serum. Levels of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were shown to be significantly elevated in several brain regions as well as in the blood serum in the vapor-exposed groups. Results of the rat study are compared to previously reported neurobehavioral evaluations of European manufacturing personnel exposed chronically to jet fuel vapor.

Ultrasonography by emergency physicians in patients with suspected ureteral colic.

We performed a prospective study of patients with suspected ureteral colic to evaluate the test characteristics of bedside renal ultrasonography (US) performed by emergency physicians (EPs) for detecting hydronephrosis, and to evaluate how US can be used to predict the likelihood of nephrolithiasis. Thirteen EPs performed US, recorded the presence of hydronephrosis, and made an assessment of the likelihood of nephrolithiasis. All patients underwent i.v. pyelography (IVP) or unenhanced helical computed tomography (CT). There were 126 patients in the study: 84 underwent IVP; 42 underwent helical CT. Test characteristics of bedside US for detecting hydronephrosis were: sensitivity 72%, specificity 73%, positive predictive value (PPV) 85%, negative predictive value (NPV) 54%, accuracy 72%. The PPV and NPV for the ability of the EP to predict nephrolithiasis after performing US were 86% and 75%, respectively. We conclude that bedside US performed by EPs may be used to detect hydronephrosis and help predict the presence of nephrolithiasis.

Critical analysis of two decades of experience with postinjury emergency department thoracotomy in a regional trauma center.

BACKGROUND: Despite numerous studies, no clear consensus exists for the optimal use of emergency department thoracotomy (EDT). As such, we have continued to critically review our experience with EDT during the last 23 years to clarify indications for EDT and evaluate its cost-effectiveness. METHODS: This was a retrospective review of 950 EDTs performed at our regional Level I trauma center during the last 23 years. Cost-benefit ratios were calculated using standardized models. RESULTS: In 23 years, 950 patients underwent postinjury thoracotomy. We were able to obtain the complete medical records for 868 patients (91%). Overall survival was 4.4%, with 3.9% surviving functionally intact. All survivors of blunt trauma had either palpable pulse or recorded blood pressure in the field. Blunt trauma functional survival when field vital signs were present was 2.5%. Of note, 26.5% of our functional survivors sustained penetrating injuries and had no pulse or blood pressure in the field. Stab wounds to the chest and gunshot wounds to the abdomen were the two mechanisms of injury most likely to be survived. The benefit-charge ratio was strongly in favor of performing EDT at 5.6:1; it was 1.8:1 if adjusted for the cost of maintaining all neurologically injured survivors throughout their lifetime. CONCLUSION: EDT is efficacious and cost-effective for select patient populations. We suggest a key clinical pathway for the use of EDT that would reduce the number of procedures by at least 32% without changing the number of neurologically intact survivors.

Effects of ammonium dinitramide on preimplantation embryos in Sprague-Dawley rats.

Ammonium dinitramide (ADN) is a class 1.1 oxidizer that may be used in rocket propellants and explosives. Previous studies have shown that ADN is a female reproductive toxicant, causing implantation failure in Sprague-Dawley rats when it is administered during the preimplantation period of gestation. The purpose of this follow-up study was to identify the mechanism(s) associated with implantation failure following exposure to ADN. Mated female rats were treated with 2.0 grams per liter (g l-1) ADN in their drinking water for 24, 48, 72, or 96 h before preimplantation embryos were harvested from the oviducts or uterine horns. On gestation day 1 (GD-1), comparable numbers of morphologically normal two-cell embryos were harvested from the oviducts of the treatment and control groups. On GD-2, the development of the embryos harvested from the treated animals was either slowed or halted when compared to the control embryos. By GD-4, 98% of the embryos harvested from the control group had developed to the morula or blastocyst stage; these were collected from the uterine horns. On GD-4 in the treated group, 41% of the harvested embryos remained at the two- to six-cell stage and 59% were degenerate; 82% of these embryos were collected from the oviducts. These data suggest that the implantation failure seen in animals treated with ADN is due to embryolethality.

Renal ultrasonography.

Renal US is one of several imaging modalities available to the emergency physician in the evaluation of patients with acute urologic disorders. It offers excellent anatomic detail without exposure to radiation or contrast agents but does not assess renal function. It is particularly useful in the evaluation of renal colic, although its role here may decrease with increasing availability of helical CT. It also has an important role in excluding bilateral renal obstruction as the cause of acute renal failure. Doppler renal US is likely to take on a more prominent role in the evaluation of renal trauma and is the diagnostic study of choice to rule out renal vein thrombosis. Bedside emergency renal US performed and interpreted by emergency physicians with limited training and experience is gaining in use and acceptance. Its role at present is primarily to identify unilateral hydronephrosis in patients with suspected renal colic. This role is likely to expand in the future as emergency US use grows and technology advances. Bedside emergency renal US may eventually be used in the evaluation of patients with acute renal failure, suspected renal vein thrombosis, and renal trauma.

Blind nasotracheal intubation in the presence of facial trauma.

Blind nasotracheal intubation (BNTI) is an effective procedure for the intubation of trauma patients. The presence of major facial trauma has been considered a relative contraindication due to the perceived risk of intracranial placement. The purpose of the present study was to assess the risk of intracranial placement in patients with facial fractures who undergo BNTI. The records of 311 patients with facial fractures were reviewed for methods of intubation and complications. Eighty-two patients underwent BNTI. There were no cases of intracranial placement, significant epistaxis requiring nasal packing, esophageal intubation, or osteomyelitis. Three patients (4%) developed sinusitis and eight (10%) developed aspiration pneumonia. We conclude that the presence of facial trauma does not appear to be a contraindication to BNTI.

The efficacy of intravenous droperidol in the prehospital setting.

Droperidol is used for sedating combative patients in the emergency department (ED). We performed a randomized, prospective, double-blind study to evaluate the efficacy of droperidol in the management of combative patients in the prehospital setting. Forty-six patients intravenously received the contents of 2-cc vials of saline or droperidol (5 mg). Paramedics used a 5-point scale to quantify agitation levels prior to and 5 and 10 min after administration of the vials. Twenty-three patients received droperidol and 23 received saline. At 5 min, patients in the droperidol group were significantly less agitated than were patients in the saline group. At 10 min, this difference was highly significant. Eleven patients in the saline group (48%) required more sedation after arrival in the ED versus 3 patients (13%) in the droperidol group. We conclude that droperidol is effective in sedating combative patients in the prehospital setting.

Acute and subchronic inhalation studies on trifluoroiodomethane vapor in Fischer 344 rats.

Trifluoroiodomethane (CF3I) is being considered as a replacement compound for halon fire suppressants. Its structure is similar to that of Halon 1301 (CF3Br), but it has very low ozone depletion potential compared to CF3Br. As part of the process of developing environmental and health effects criteria, acute, 2-week, and 13-week nose-only inhalation toxicity studies were conducted in Fischer 344 rats. In the acute study, three groups of 30 male rats each were exposed to 0 (control), 0.5, or 1.0% (v/v) CF3I for 4 hr and euthanized immediately following exposure, 3 days postexposure, or 14 days postexposure. There were no deaths and no clinical signs of toxicity throughout the study. Histopathologic examination of select tissues showed no lesions of pathologic significance. In the 2-week study, four groups of 5 male rats each were exposed for 2 hr/day, 5 days/week to 0, 3, 6, or 12% CF3I. No deaths were observed, though lethargy and slight incoordination were noted in rats of the 6 and 12% groups at the conclusion of each daily exposure. Mean body weight gains were depressed in rats of the 6 and 12% groups. Serum thyroglobulin and reverse T3 (rT3) values were increased at all exposure levels. At necropsy, no gross lesions or differences in absolute or relative organ weights were noted. Histopathologic examination of the thyroid and parathyroid glands indicated no morphological abnormalities in the CF3I-exposed rats. In the 13-week study, four groups of 15 male and 15 female rats were exposed to 0, 2, 4, or 8% CF3I 2 hr/day, 5 days/week for 13 weeks. Rats exposed to 4 or 8% CF3I had lower mean body weights than the controls. Deaths observed in the 2 and 8% groups were attributed to accidents resulting from the restraint system employed. Hematologic alterations were minimal and considered insignificant. Increases in the frequency of micronucleated bone marrow polychromatic erythrocytes were observed in rats of all three CF3I groups. Serum chemistry alterations observed in rats of all CF3I exposure groups included decreases in T3 and increases in thyroglobulin, rT3, T4, and TSH. Relative organ weight increases (8% CF3I group) occurred in the brain, liver, and thyroid glands; decreases were observed in the thymus and testes. A decrease in relative thymus weights and an increase in relative thyroid weights were observed also in rats of the 2 and 4% groups. Histopathological findings included a mild inflammation in the nasal turbinates of rats exposed to 4 or 8% CF3I, mild atrophy and degeneration of the testes (4 and 8% CF3I groups), and a mild increase in thyroid follicular colloid content in rats of all CF3I exposure groups. Though NOAELs were observed for select target organs (e.g., nasal turbinates, testes), NOAELs were not apparent in all target organs examined (e.g., thyroid glands, bone marrow).

Dose- (and time-) dependent blockade of pregnancy in Sprague-Dawley rats administered ammonium dinitramide in drinking water.

Ammonium dinitramide (ADN) is a class 1.1 explosive oxidizer that can be used in solid rocket propellant mixtures and explosives. A 90-day general toxicity/ reproductive screen performed on this compound at doses of 162, 103, 29, and 0.0 mg ADN/kg/day resulted in a treatment-related adverse effect on litter production. Incidences of animals producing litters (1/11, 3/12, 12/12, and 11/12, respectively) and mean numbers of pups per litter (7, 7, 16, and 15, respectively) both were statistically significantly less than controls. In a follow-up study, mated dams treated with ADN at the same doses and examined at gestation days (GDs) 10 and 20 showed an effect in fetus loss similar to that seen in the reproductive screen. A pre- versus postimplantation dosing regimen indicated that implantation is vulnerable to ADN effects during the preimplantation period (GDs 1-3). No implantation sites were found in the rats treated with 2000 mg ADN/L drinking water (target dose of 160 mg ADN/kg/day) during GDs 1-3. Numbers of implantation sites found in the rats treated during GDs 4-8 were similar to those found in the control group. The pituitary was not identified specifically in this study as the site of primary action, but serum progesterone was reduced by 27%, which may have resulted in reduced fertility.

Quantitative sensitivity of ultrasound in detecting free intraperitoneal fluid.

The minimum volume of intraperitoneal fluid that is detectable in Morison's pouch with ultrasound in the trauma setting is not well defined. To evaluate this question, we used diagnostic peritoneal lavage (DPL) as a model for intraperitoneal hemorrhage and undertook a blinded prospective study of the sensitivity of ultrasound in detecting intraperitoneal fluid. Participants included attending physicians and residents in emergency medicine, radiology, and surgery. During the infusion of the DPL fluid, participants continuously scanned Morison's pouch until they detected fluid. All participants were blinded to the rate of infusion and the volume infused. One hundred patients were entered into the study. The mean volume of fluid detected was 619 mL. Only 10% of participants detected fluid volumes less than 400 mL and the overall sensitivity at one liter was 97%. We conclude that reliable detection of intraperitoneal fluid in Morison's pouch requires a greater volume than has been previously described.

Reproductive toxicity screen of ammonium dinitramide administered in the drinking water of Sprague-Dawley rats.

The Department of Defense is currently considering replacing ammonium perchlorate with ammonium dinitramide (ADN), a class 1.1 explosive oxidizer to be used in solid rocket propellant mixtures and explosives. This study was intended to evaluate the potential of ADN to produce alterations in paternal fertility, maternal pregnancy and lactation, and growth and development of offspring. Male and female rats received drinking water containing 0.0, 0.2, 1.0, or 2.0 g ADN/liter throughout the study. Mating occurred following 14 days of treatment. All dams, one-half the males, and representative pups were maintained for a total of 90 days of treatment. No mortality occurred in parental animals during the study. Treatment with ADN resulted in no adverse effects on mating; 92-100% of the animals mated. No treatment-related effects were seen in parental animals clinically or histopathologically. Adverse treatment-related effects were noted in maternal and paternal fertility indices, gestational indices, and live birth indices in both the mid- and high-dose groups. Litter sizes in the mid- and high-dose groups were significantly smaller than those of the low-dose and control groups. Mean pup weights showed no statistically significant differences between ADN-treated pups and controls. Gross and histopathological examination of the animals failed to identify the cause for the decrease in litter production in the mid- and high-dose dams. This study indicates that ADN is a reproductive toxicant. The no-observable-effect level (NOEL) is 29 mg/kg/day, the median dose of the low level female rats.

Reproductive toxicity screen of 1,3,5-trinitrobenzene administered in the diet of Sprague-Dawley rats.

Several Army installations targeted for restoration have measurable quantities of 1,3,5-trinitrobenzene (TNB) in the soil and groundwater. As part of the process of developing environmental and health effects criteria for restoration, a modified Screening Information Data Set (SIDS) reproductive study was performed. Male and female Sprague-Dawley rats received a diet containing approximately 30, 150, or 300 mg TNB/kg diet. Mating occurred following 14 days of treatment. All dams, one-half the males, and representative pups were maintained for a total of 90 days of treatment. No mortality occurred during the study; however, a decrease in mean body weights was noted in both sexes of high-dose rats. A dose-related effect was noted in measurements of sperm function/activity. Sperm depletion and degeneration of the seminiferous tubules were noted histopathologically. Methemoglobinemia and splenic hemosiderosis were common findings in the high- and mid-dose levels of both sexes at necropsy. No adverse effects were noted in mating or fertility indices. No significant treatment-related differences were found in length of gestation, sex ratio, gestation index, or mean number of pups per litter.

General toxicity and reproductive screen of liquid propellant XM46 administered in the drinking water of Sprague-Dawley rats.

Liquid propellant XM46 is being considered as a replacement for solid propellants, both as part of a regenerative injection gun system and as a working fluid in an electrothermal gun system. The XM46 formulation contains hydroxylammonium nitrate, triethanolammonium nitrate, and water. Male and female Sprague-Dawley rats received XM46 in drinking water containing 2.0, 1.0, 0.2, or 0.0 g XM46/liter throughout a 90-day study. Mating occurred following 14 days of treatment. One-half the male rats per group were necropsied after 28 days of treatment; the remaining males and all dams were necropsied following 90 days of treatment. No mortality occurred in any of the parental animals during the study. The study did not demonstrate any adverse effects on reproduction or litter parameters. Hemolytic anemia and methemoglobinemia were common in both sexes of rats. Splenomegaly was found in both sexes; in male rats as early as 28 days. Exposures via drinking water containing XM46 for 90 days did not result in any decrease in reproductive performance in male or female rats, but it did result in clinical signs of hemolytic anemia at doses as low as 17 mg/kg/day.

N-methyl-N'-nitroguanidine: irritation, sensitization, and acute oral toxicity, genotoxicity, and methods for analysis in biological samples.

Currently, N-methyl-N'-nitroguanidine (MNG) is being considered by the U.S. Air Force Armament Laboratory for use in explosive formulations. A mammalian toxicity profile has been performed which includes the analysis of chemical impurities and an assessment of the potential for the metabolism of MNG to 1-methyl-3-nitro-1-nitrosoguanidine (MNNG). Potential in situ gastric conversion of MNG to MNNG is a toxicological concern because MNNG is both mutagenic and carcinogenic. The compound was also evaluated in several bioassays to assess its potential genotoxic activity. The acute oral toxicity was determined in male and female Fischer 344 rats administered a single dose of MNG in corn oil. The maximum suspension of MNG that could be delivered, 1 mg MNG/kg body weight, produced no signs of toxic stress during the 14-day observation period. The primary eye and skin irritation potential of MNG was determined in female New Zealand white rabbits using the Draize technique. MNG produced no irritation to intact skin but did produce mild conjunctival irritation. The response of a single guinea pig to the dermal sensitization evaluation indicated that MNG is a weak sensitizer. The results of three genetic tests indicated that MNG does not interact with genetic material. Gastric contents and feces from treated animals showed no evidence of conversion of MNG to MNNG.

The acute toxicity evaluation of a low-temperature hydraulic fluid.

A low-temperature version of MIL-H-83282 (LT 83282) is a candidate hydraulic fluid to be used as a replacement for the current low-temperature fluid used on Strategic Air Command aircraft. A single neat dose of 0.1 mL LT 83282 into New Zealand White (NZW) rabbit eyes resulted in slight conjunctival irritation for up to 24 hr after treatment in two of nine rabbits. Rinsing the eyes after treatment appeared beneficial. A single treatment of 0.5 mL neat LT 83282 to rabbit skin produced no irritation. A total of 40% of the guinea pigs receiving repeated dermal application of the fluid demonstrated a positive sensitization response. A single oral dose of 5 g LT 83282/kg body weight given to five male and five female Fischer 344 (F-344) rats and a single dermal application of 2 g LT 83282/kg body weight applied to five male and five female NZW rabbits resulted in no deaths. Inhalation exposures to aerosol concentrations of LT 83282 resulted in an LC50 of 2.13 and 1.50 mg/L for male and female F-344 rats, respectively. No clinical signs of acute delayed neurotoxicity were observed in hens twice dosed at limit levels (5 g/kg) and observed for 21 days.

Evaluation of the acute toxicity of silahydrocarbon.

Silahydrocarbon (SHC) is a base stock for a candidate high-temperature hydraulic fluid. Because United States Air Force personnel working with SHC may be exposed to potential health hazards, a complete battery of acute toxicity tests was performed with the fluid. A single neat dose of 0.1 mL SHC into New Zealand White (NZW) rabbit eyes resulted in slight conjunctival irritation 1 hr after treatment in all unflushed eyes and one of three flushed eyes. Conjunctival irritation persisted through 24 hr but dissipated by 48 hr. Rinsing the eyes after treatment was of questionable benefit. A single treatment of 0.5 mL neat SHC to rabbit skin produced negative results for all but a single animal, which had very slight erythema at the test site 48 hr after treatment. Guinea pigs failed to exhibit a sensitization response following repeated application of SHC. A single oral dose of 5 g SHC/kg body weight given to five male and five female F-344 rats and a single dermal dose of 2 g SHC/kg body weight applied to five male and five female NZW rabbits resulted in no deaths or signs of toxic stress. Five male and five female F-344 rats were exposed to 4.8 mg/L (near limit concentration) of aerosolized SHC for 4 hr. All male rats and four female rats survived. During exposure, the animals exhibited signs of eye and upper respiratory irritation.