Blood lead levels in emergency department patients with retained lead bullets and shrapnel.

OBJECTIVE: To determine whether patients with retained lead shrapnel who present to the ED have elevated whole blood lead levels (BLLs) compared with matched control patients. METHODS: Test subjects were patients with x-ray evidence of retained lead shrapnel who presented to any of three urban EDs, and consented to inclusion in the study. BLLs were obtained from 15 ED patients, and data regarding time since injury and symptoms of plumbism were collected. Control subjects consisted of 15 ED patients, without similar lead exposure, matched for age, sex, race, and place of dwelling as determined by zip code, who also presented to any of the same three EDs. RESULTS: The mean (+/-SD) BLL in the test subjects was 17+/-9.78 microg/dL (range 7-50 microg/dL). Time since impalement ranged from 1 to 45 years. The mean BLL in the control subjects was 7+/-3.77 microg/dL (0-16 microg/dL). This difference was statistically significant (two-tailed t-test p = 0.002). CONCLUSIONS: In this preliminary study, the patients with retained lead shrapnel who presented to the ED had significantly elevated BLLs, compared with the matched control subjects. Chronic plumbism may be considered in patients with retained lead shrapnel, and a history should be taken to assess the presence of symptoms referable to plumbism. These patients may require long-term follow-up to assess the development of elevated blood lead level and lead toxicity.

Advantage of high-surface-area charcoal for gastrointestinal decontamination in a human acetaminophen ingestion model.

OBJECTIVE: To compare the abilities of low-surface-area (LSA) vs 2 types of high-surface-area (HSA) activated charcoal given orally to adsorb acetaminophen in the gastrointestinal (GI) tract, as demonstrated by the impact of these agents on the serum levels and area under the curve (AUC) in a simulated human overdose model. METHODS: The main arm of the study was a prospective double-blind crossover trial in which 6 volunteers, serving as their own controls, ingested acetaminophen (50 mg/kg), followed randomly in 10 minutes by either powdered LSA charcoal (950 m2/g) or powdered HSA charcoal (2,000 m2/g) in a charcoal:drug ratio of 8:1. In a second arm of the study, 3 subjects additionally ingested an equal dose of a granular preparation of the HSA charcoal. Serial serum acetaminophen levels were analyzed at various intervals (30, 60, 90, 120, 180, 240, and 300 minutes postingestion), and a 5-hour AUC was calculated. The subjects also rated the charcoal preparations for palatability. RESULTS: Serum acetaminophen levels were lower at all measured times in the groups receiving both forms of the HSA charcoal vs the LSA product. With the powdered HSA charcoal, comparison serum levels were significantly lower at 120 minutes postingestion and all times thereafter (p < 0.05), reaching high significance at 4 and 5 hours (p < 0.001). The subjects receiving the granular HSA charcoal also had consistently lower serum acetaminophen levels than did those receiving the LSA product, and the difference in mean serum levels was significant at the 4- and 5-hour sample (p = 0.012). Compared with the LSA charcoal, at the 4-hour postingestion sample, serum acetaminophen levels were reduced by 44% to 85% by the powdered HSA charcoal. The total AUC for the 5-hour study period was also significantly reduced by the powdered HSA product (p = 0.005) and the granular HSA product (p = 0.043). All the subjects rated the powdered HSA charcoal to be more palatable and easier to drink than the powdered LSA charcoal. CONCLUSION: The surface area of oral activated charcoal is a major determining factor in its ability to limit acetaminophen absorption and to fulfill its adsorptive role in GI decontamination. In a human acetaminophen overdose model, 2 types of HSA charcoal, when compared with equal doses of LSA charcoal, significantly reduced serum levels and total acetaminophen absorption as measured by the AUC.

A new model of uncontrolled hemorrhage that allows correlation of blood pressure and hemorrhage.

OBJECTIVE: To compare hemodynamics, mortality rates, and bleeding rates at 3 severities of hemorrhage in a new model of uncontrolled intra-abdominal bleeding that uses an injury of varying severity and geometry unfavorable to thrombosis. METHODS: Ten swine were bled through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. The shunt was connected to catheters of varying diameters placed in the femoral artery to create 3 rates of hemorrhage. Blood flow through the shunt was measured with an in-line Doppler probe. Arterial pressures, cardiac output (CO), and ECGs were monitored. Survival and blood loss were calculated. RESULTS: The model successfully produced 3 hemorrhage severities. At all 3 rates of bleeding, blood flow was linearly related to mean arterial pressure, with R2 > 0.72. Bleeding was continuous in all groups. The mean numbers of minutes until death were 53, 45, and 25, respectively, at the increasing shock severities. Blood pressure (BP) and CO decreased continuously in all groups, but did so more rapidly with increasing severity of hemorrhage. CONCLUSIONS: In this model of uncontrolled hemorrhage, bleeding was continuous and linearly related to BP. The hemodynamic response to uncontrolled bleeding in this model differs markedly from those in previous wire aortotomy models where wound geometry is favorable to thrombosis. Hence, when injury geometry is favorable to thrombosis (as in aortotomy), thrombosis formation affects hemorrhage rates and hemodynamic responses.

Effect of permissive hypotension in continuous uncontrolled intra-abdominal hemorrhage.

OBJECTIVE: To determine the effects of aggressive fluid administration vs permissive hypotension on survival, blood loss, and hemodynamics in a model of uncontrolled hemorrhage in which bleeding has been shown to be continuous. METHODS: In this porcine model, 10 animals were bled through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. The animals received either no fluid (n = 5) or 80 mL/kg lactated Ringer's solution (n = 5) during a resuscitation phase between 10 and 20 minutes postinjury, followed by a 40-minute evaluation phase. Arterial pressures, cardiac output (CO), and hemorrhage rate were measured. Survival and blood loss were calculated outcome measures. RESULTS: The difference in survival between the animals left hypotensive (40%) and those receiving normotensive resuscitation (20%) was not significant (p = 0.49). In the animals receiving fluid resuscitation, mean arterial pressure (MAP) and CO increased during the resuscitative phase, but all the animals suffered the same pattern of hemodynamic deterioration in the evaluation phase. Rate of hemorrhage during the resuscitative phase was 20 +/- 5 mL/min in the animals not receiving fluid and 56 +/- 9 mL/min in the animals receiving fluids. Total blood loss was subsequently 20 mL/kg greater in the animals receiving fluids than in the animals without fluid resuscitation. CONCLUSIONS: In this model of continuous uncontrolled hemorrhage, the difference in survival between the animals left hypotensive and the animals receiving fluid resuscitation was not statistically significant. Increases in MAP and CO with fluid resuscitation were transient and were offset by larger volumes of blood loss. In contrast to the aortotomy model (where thrombosis is likely and hypotensive resuscitation has proven beneficial), this model suggests that in continuous bleeding avoiding fluid resuscitation has a much smaller effect on outcome. Much of the benefit from hypotensive resuscitation may depend on having an injury that can stop bleeding.

Comparison of intermittent and continuously nebulized albuterol for treatment of asthma in an urban emergency department.

STUDY OBJECTIVE: To compare continuously nebulized albuterol with intermittent bolus nebulization of albuterol. DESIGN: Consecutive block enrollment in groups of ten to continuous or intermittent therapy. SETTING: Urban emergency department. TYPE OF PARTICIPANTS: Patients who presented to the ED with moderate to severe asthma and did not improve after one treatment with nebulized albuterol. INTERVENTIONS: All patients received an initial nebulized treatment with 2.5 mg albuterol followed by 125 mg solumedrol. Patients in the intermittent group received 2.5 mg nebulized albuterol at 30, 60, 90, and 120 minutes after the initial treatment. Patients in the continuous group received 10 mg albuterol nebulized in 70 mL over two hours. RESULTS: There was no difference between groups in age, sex, or initial peak expiratory flow rate (PEFR). Ninety-nine patients were included in the study (47 continuous and 52 intermittent). There was no statistically significant difference in PEFRs or admission rate between groups over the two-hour study period. One subgroup analysis was performed on patients with PEFRs on presentation to the ED of 200 L/min or less. Mean +/- SD baseline PEFR at presentation to the ED was 135 +/- 35 in the 35 patients in the continuous group and 137 +/- 45 in the 34 patients in the intermittent group). At 120 minutes, PEFR was 296 +/- 98 in the continuous group and 244 +/- 81 in the intermittent group (P = .01). Admission: discharge ratios for this subgroup analysis were 11:24 in the continuous group and 19:14 in the intermittent group (P = .03). Mean +/- SD heart rate in the subgroup analysis was 102 +/- 21 at baseline for the continuous group and 109 +/- 22 at baseline in the intermittent group. At 120 minutes, heart rate was 90 +/- 18 in the continuous group and 104 +/- 16 in the intermittent group (P = .002). CONCLUSIONS: Continuous nebulization offers no benefit over intermittent therapy in patients with an initial PEFR of more than 200 L/min. In PEFRs of 200 or less, continuous nebulization may decrease admission rate and improve PEFRs when compared with standard therapy.

Inefficacy of intraperitoneal fluid administration in a shock model.

Intraperitoneal (IP) fluid administration has been previously used to treat dehydrated children. The relative ease and reported safety of this route suggests its potential utility for volume resuscitation in the acutely ill child. Previous research regarding IP fluid infusion has not examined its use in shock states. This experiment sought to examine the efficacy of an IP fluid infusion in a shock model. Ten immature swine were randomized to receive either no treatment (n = 5) or 30 ml/kg of warmed lactated Ringer's solution (n = 5) IP 20 minutes after a graded 40% hemorrhage. Mean arterial pressure (MAP), heart rate (HR), hematocrit (Hct), pH, and PCO2 were determined serially, and the experiment concluded 60 minutes after intervention. A mean of 89.5% of the administered fluid load was recovered from the peritoneal cavity, and the IP infusion had no ameliorative effect on MAP or HR. The lack of clinically significant absorption of an administered isotonic intraperitoneal fluid infusion in this model suggests that this route should not be relied upon in the critically ill child presenting in shock.

The influence of age and sex on asthma admissions.

OBJECTIVE: To describe demographic data from a large population of asthmatic patients to define the role of age and sex as risk factors for asthma admission. DESIGN: A retrospective review of all asthma admissions as defined by International Classification of Diseases, Ninth Revision, code 493.0. SOURCE: All medical-surgical admissions from 67 hospitals in five counties of southeastern Pennsylvania from 1986 through 1989. RESULTS: Patients admitted for asthma treatment (33,269) were reviewed. In the 0- to 5-year-old and 6- to 10-year-old age groups, males were admitted nearly twice as often as age-identical females. In the 11- to 20-year-old age group, admissions for males and females were nearly identical. Between 20 and 50 years of age, the female-to-male ratio was nearly 3:1. Thereafter, females were admitted for asthma at a rate of about 2.5:1 when compared with their age-equivalent male counterparts. Length of stay increased proportionally as the patient age increased. After 30 years of age, the length of stay was slightly greater for females than males. CONCLUSIONS: There is a much higher rate of admission for prepubertal males than females. However, there is a higher incidence of asthma admissions for adult females than adult male asthmatic patients, and female asthmatic patients experience longer hospital stays per admission as well. These data indicate that adult females are more severely affected by asthma and raise the possibility that hormonal or biochemical differences related to sex may play a role in the pathophysiology of asthma.

Plasma catecholamine levels after intraosseous epinephrine administration in a cardiac arrest model.

STUDY OBJECTIVE: To measure plasma catecholamine levels and the cardiovascular response after administering epinephrine by the intraosseous (IO) route in an animal cardiac arrest model. MODEL: Eighteen anesthetized swine (weight, 12 to 15 kg) subjected to five minutes of electrically induced ventricular fibrillation followed by 25 minutes of chest compression and ventilation. INTERVENTIONS: Animals were anesthetized with 30 mg/kg IM ketamine and 75 mg/kg IV a-chloralose, intubated, placed on a respirator, and surgically instrumented. Ventricular fibrillation was induced. After five minutes of cardiac arrest, mechanical chest compressions were initiated and continued until the end of the experiment. Animals received 0.01 mg/kg IO epinephrine (five) or 0.1 mg/kg IO epinephrine (five) at ten and 20 minutes. The eight controls did not receive epinephrine. MEASUREMENTS AND MAIN RESULTS: Plasma epinephrine levels increased from 1.0 to approximately 40 to 85 ng/mL with the initiation of CPR. Epinephrine (0.01 mg/kg) increased plasma epinephrine levels to 222 +/- 72 ng/mL at 12 minutes after arrest but did not increase diastolic or mean blood pressure. Epinephrine (0.1 mg/kg) increased plasma epinephrine levels to 1,103 +/- 157 ng/mL at 12 minutes after arrest and increased diastolic and mean arterial blood pressures. CONCLUSION: IO epinephrine is rapidly transported to the central circulation but requires larger than currently recommended doses to produce a significant change in blood pressure.

Effects of calcium channel blocker overdose-induced toxicity in the conscious dog.

STUDY OBJECTIVE: To evaluate the effects of nifedipine, diltiazem, and verapamil overdose on systemic hemodynamics and blood flows to the coronary, superior mesenteric, renal, and iliac arteries in the unanesthetized dog. DESIGN: Nonblinded, controlled animal study. SETTING: Research laboratory of a large pharmaceutical company. TYPE OF PARTICIPANTS: Nineteen healthy mongrel dogs obtained from a commercial supplier. INTERVENTIONS: Under general anesthesia, flow probes were placed about the ascending aorta, circumflex coronary, superior mesenteric, renal, and iliac arteries; a micromanometer was implanted into the tip of the left ventricle; and a catheter was inserted into the descending aorta. Experiments were performed after a recovery period of at least two weeks. MEASUREMENTS AND MAIN RESULTS: Arterial blood pressure, heart rate, cardiac output, left ventricular pressure, and regional blood flows were measured prior to drug administration, and after 0.03, 0.1, 0.3, 1.0, and 3.0 mg/kg IV administration of the study drugs. Dogs receiving diltiazem or verapamil also received a dose of 10.0 mg/kg. When the blood pressure had been reduced from baseline by 30%, 1.43 mg/kg nifedipine IV (six dogs) decreased total peripheral resistance by 51%, increased cardiac output by 35%, and increased heart rate by 132%. Coronary blood flow and iliac blood flow increased 93% and 45%, respectively, but mesenteric blood flow and renal blood flow were not significantly altered. Diltiazem (eight) and verapamil (seven) at equivasodepressor doses (1.43 to 4.43 mg/kg) caused less peripheral vasodilation and reflex tachycardia. At severely toxic levels when arterial blood pressure fell by 50%, all three drugs decreased cardiac output. Nifedipine still increased heart rate. Diltiazem and verapamil caused high-grade atrioventricular block, resulting in bradycardia. All three drugs caused a redistribution of cardiac output favoring the coronary bed over the other beds. CONCLUSIONS: In the conscious dog, calcium channel blocker-induced hypotension at the moderate level is associated with disparate effects on systemic hemodynamics, probably resulting from differential reflex sympathetic activation. However, at a more severe level, their toxic effects are similar and manifested predominantly by their actions on the slow calcium channel.

Serum glucose after intraperitoneal infusion of 5% dextrose solution.

STUDY OBJECTIVE: This study investigated the use of intraperitoneal (IP) glucose infusion as a therapy for hypoglycemia. DESIGN: Randomized, placebo-controlled, crossover design, with each animal serving as its own control. SETTING: Laboratory investigation. TYPE OF PARTICIPANTS: Seven female New Zealand White rabbits with a mean weight of 3.7 kg. INTERVENTIONS: Each animal was subjected to three experiments separated by a four-day period. After baseline measurements, the following interventions were undertaken: Control day, no treatment; placebo day, 10 mL/kg 0.9% normal saline solution IP; and treatment day, 10 mL/kg 5% dextrose solution IP. MEASUREMENTS AND MAIN RESULTS: Serial serum glucose levels were obtained. Compared with control and placebo, the mean absolute serum glucose value of the treatment group was significantly higher beginning at ten minutes after intervention and continuing until conclusion of the study at 30 minutes. For these time points, the mean increase in serum glucose levels (percent change) of the treatment group compared with the control group was as follows: ten minutes, 15.5 mg/dL (0.86 mmol/L) (11%), P less than .01; 15 minutes, 20.6 mg/dL (1.14 mmol/L) (14%), P less than .01; 20 minutes, 36.5 mg/dL (2.03 mmol/L) (26%), P less than .001; and 30 minutes, 34.7 mg/dL (1.93 mmol/L) (24%), P less than .001. CONCLUSION: Glucose instilled into the peritoneal cavity of rabbits is absorbed rapidly into the systemic circulation.

Comparison of two doses of endotracheal epinephrine in a cardiac arrest model.

STUDY OBJECTIVE: The objective of this study was to measure plasma catecholamine levels and the cardiovascular response before and after endotracheal administration of epinephrine in a swine cardiac arrest model. DESIGN: Prospective, controlled laboratory investigation. TYPE OF PARTICIPANTS: Twenty-one swine weighing 10 to 12 kg, anesthetized with ketamine and alpha-chloralose and ventilated with room air. INTERVENTIONS: Ventricular fibrillation was induced with 90 V of 60 Hz current delivered to the right ventricle by transvenous pacemaker. Blood samples for epinephrine were drawn before arrest and every two minutes thereafter. At five minutes, external mechanical cardiac compressions were initiated. Nine animals received no further therapy and served as controls. Two groups of six animals received either 0.01 mg/kg or 0.1 mg/kg of epinephrine through the endotracheal tube at ten and 20 minutes. Blood samples were assayed for epinephrine. MEASUREMENTS: Arterial blood pressure, lead II ECG, and plasma epinephrine. MAIN RESULTS: Swine receiving epinephrine 0.01 mg/kg had an increase in epinephrine levels after drug administration, but these were not significantly different from control levels. The 0.1-mg/kg dose group had a significant increase in plasma epinephrine levels compared with controls and the 0.01-mg/kg dose group after receiving epinephrine at ten and 20 minutes. These increases were from 14 +/- 3 to 215 +/- 40 ng/mL (+/- SEM) at 12 minutes after arrest and from 151 +/- 56 to 402 +/- 80 ng/mL at 22 minutes after arrest. CONCLUSION: These data suggest that standard dosing of epinephrine through the endotracheal tube during arrest does not produce significant increases in plasma catecholamines or blood pressure. Epinephrine 0.1 mg/kg produces a significant increase in plasma epinephrine levels, but it is not sufficient to produce a significant change in blood pressure.

Endogenous and exogenous plasma catecholamine levels in cardiac arrest in swine.

The use of epinephrine in cardiac arrest remains an area of continuing controversy. This study was undertaken to characterize the effect of endogenous and exogenous epinephrine on plasma epinephrine levels, and the relationship between plasma epinephrine and norepinephrine and mean arterial pressure and diastolic arterial pressure. Nineteen young swine were anesthetized with ketamine and alpha-chloralose and instrumented with arterial and central venous lines. Ventricular fibrillation was induced by pacemaker. At 5 min post arrest cardiopulmonary resuscitation (CPR) was begun with a mechanical resuscitator. Animals were randomized to receive either saline placebo (n = 9), 0.01 mg/kg epinephrine (n = 5) or 0.1 mg/kg epinephrine (n = 5) via the central venous line. Plasma was drawn for high pressure liquid chromatographic analysis of catecholamines every 2 min. The resuscitation was carried on for 30 min after the arrest. Plasma epinephrine levels differed significantly between treated subjects and controls, as did mean arterial pressure and diastolic arterial pressure. There was a correlation between both mean arterial pressure and diastolic arterial pressure with plasma epinephrine and log epinephrine, but no correlation with plasma norepinephrine. The two doses of epinephrine did not differ in the degree to which they elevated the mean arterial pressure and diastolic pressure. We conclude that the endogenous catecholamine response to cardiac arrest while producing norepinephrine and epinephrine levels many times greater than those in the resting animal, is not sufficient to maintain blood pressure. There is a strong correlation between blood pressure and the log of the plasma epinephrine concentration, but epinephrine concentration alone does not solely account for changes in blood pressure during arrest.

Plasma catecholamines, pH, and blood pressure during cardiac arrest in pigs.

This study examined plasma epinephrine (E) and norepinephrine (NE) concentrations, pH, and mean arterial blood pressure (MAP) in a cardiac arrest model. Twenty-three domestic swine (15-26 kg) were anesthetized with ketamine 20 mg/kg, i.m. and alpha-chloralose 25 mg/kg, i.v. and ventilated with a respirator. Catheters were placed in the right ventricle, left ventricle and femoral arteries for MAP recordings and blood pH sampling every 2 min. Catecholamine samples were taken from the femoral artery every 2 min. Cardiac arrest was induced by endocardial stimulation with a Grass S88 stimulator. Five minute post arrest resuscitation was initiated with a mechanical resuscitator. Ten minute post arrest NaHCO3 1 mEq/kg was administered by the peripheral i.v. (P; n = 6), central (CE; n = 5), or intraosseous, via the tibia, (I; n = 6), route. Controls (C; n = 6) did not receive NaHCO3. MAP (mean +/- S.D.) prior to arrest was: C 144 +/- 16, P 139 +/- 11, CE 137 +/- 13 and I 133 +/- 11 mmHg. Five and 25 min post arrest it was: C 21 +/- 5 and 17 +/- 6, P 34 +/- 8 and 23 +/- 7, CE 17 +/- 7 and 14 +/- 10 and I 26 +/- 6 and 11 +/- 3 mmHg, respectively. A 2-way analysis of variance did not reveal any difference in MAP values in the four groups. In all groups the blood pH from the femoral artery demonstrated a respiratory alkalosis that peaked at approximately 7.48 5 min after initiation of mechanical resuscitation. In the groups receiving NaHCO3, it peaked at 7.77 +/- 0.09 CE and 7.65 +/- 0.06 P 2 min post infusion and at 7.71 +/- 0.06 I 8 min post infusion. An analysis of variance revealed that the CE and I routes were significantly different (P less than 0.05) from the P group and that all three groups were different (P less than 0.05) from the C. Plasma E and NE concentrations at 0, 6, 10, 12, 20 and 30 min post arrest in the C group were, respectively: 3 and 10, 94 and 327, 119 and 329, 92 and 234, 33 and 135, and 127 and 62 ng/ml, respectively. All 3 groups receiving NaHCO3 demonstrated similar patterns and were not significantly different from C when compared with a 2-way analysis of variance.(ABSTRACT TRUNCATED AT 400 WORDS)

Intraosseous crystalloid and blood infusion in a swine model.

The technique of intraosseous infusion has attracted increasing interest in recent years, and has proven valuable for drug administration. This study was undertaken to determine whether it was also a potential route for fluid resuscitation. Thirteen- or eighteen-gauge tibial intraosseous needles were placed in eight "large" (mean weight, 14.4 kg) and eight "small" (mean weight, 5.8 kg) swine and the flow rate of blood and saline measured under gravity and 300 mm Hg. Flow was significantly greater using 13-gauge needles in the "large" swine, significantly greater for saline than for blood, and for pressure infusion versus gravity in all animals. A fluid bolus of 20 ml/kg could be given to all animals in less than 10 minutes using pressure infusion. These data suggest that intraosseous infusion is a reasonable initial step in fluid resuscitation of pediatric subjects until more conventional vascular access has been established.