The effect of a curfew on pediatric out-of-hospital EMS responses

OBJECTIVE

The purpose of a curfew is to decrease the amount of crime inflicted on minors during the late hours of the night. On June 1, 1994, a city curfew was instituted in New Orleans, requiring all persons 17 years of age or younger to be off the streets from 9 PM to 6 AM Sunday through Thursday, and from 11 PM to 6 AM on Friday and Saturday. This study evaluated the effect of the curfew on emergency medical services (EMS) transports for patients who were 17 years old or younger (pediatric).

METHODS

Data from all pediatric transports were included from the months before (5/94) and after (6/94) the institution of the curfew, and from the same two months one year earlier (5/93 and 6/93). A chi-square test was used to evaluate comparisons.

RESULTS

The city EMS transports 48,000 patients per year in a one-tiered system (paramedic only) that acts as the sole provider of emergency EMS transport in the city. Approximately 10% of all transports are pediatric, and 40% of the pediatric transports are for trauma. A total of 1,642 transports were found that fit the inclusion criteria. In May 1993, there were 415 total pediatric transports; 234 were pediatric trauma. In June 1993, there were 406 total pediatric transports; 250 were pediatric trauma. In May 1994, there were 447 total pediatric runs; 243 were pediatric trauma. During the postcurfew month, June 1994, there were a significant decrease in pediatric transports to 370 (p < 0.01) and a significant decrease in pediatric trauma transport to 189 (p < 0.01).

CONCLUSION

The institution of a curfew may lead to a drop in pediatric EMS runs during curfew hours. Another value of the curfew may be in the secondary effects of the curfew in preventing childhood injury during noncurfew hours.

Neurophysiologic effects of retrograde cerebral perfusion used for aortic reconstruction

OBJECTIVE

The results of neurophysiologic monitoring using somatosensory evoked potentials (SSEPs) and electroencephalography (EEG) were analyzed to determine if retrograde cerebral perfusion (RCP) supported central nervous system electrical function during surgery that required temporary interruption of antegrade cerebral perfusion (IACP).

DESIGN

A prospective, observational study.

SETTING

A university hospital.

PARTICIPANTS

Fifteen adult patients who underwent aortic reconstruction using RCP and three patients who underwent thoracic aortic operations using hypothermic circulatory arrest without RCP.

INTERVENTIONS

SSEPs and EEG were monitored continuously throughout the operation. Regression analysis was performed to determine the factors that affected the rate of decrease in SSEP amplitudes during IACP and the time required for SSEP and EEG activity to recover after antegrade cerebral perfusion (ACP) was restored.

MEASUREMENTS AND MAIN RESULTS

The amplitude of SSEPs that were elicited decreased over time after IACP. The mean +/- standard deviation (SD) time required for the brachial plexus (Erb's point), cervicomedullary junction (N13), and brainstem (N18) SSEPs to decrease to 0.5 of their original amplitude after IACP were 30 +/- 2, 19 +/- 2, and 16 +/- 2 minutes, respectively. The rate of decrease in the N18 SSEP amplitude after IACP correlated positively to the fraction of no-flow time (p = 0.01).

CONCLUSION

RCP attenuated the rate of decay in SSEP amplitudes during IACP. This suggested that RCP had a measurable physiologic effect on central nervous system function and may increase the time that ACP can be safely interrupted.

Motivational effects of compounding discriminative stimuli associated with food and cocaine

In previous experiments, the compounding of two discriminative stimuli associated with the same reinforcer increased rats' responding approximately three-fold, regardless of whether the reinforcer was food, water, cocaine, or shock-avoidance. Compounding a discriminative stimulus associated with food with one associated with water increased responding two-fold. In the present experiment, compounding a discriminative stimulus associated with food with one associated with cocaine increased responding two-fold. These results support the hypothesis that 1) the effects of stimuli associated with reinforcers from the same incentive class (appetitive or aversive) are mutually enhancing, and 2) the combined effects of stimuli associated with two different reinforcers from within the same class are not as strong as those of two stimuli associated with the same reinforcer. These results also suggest that discriminative stimuli associated with non-drug reinforcers may increase the motivation to self-administer cocaine when encountered in combination with drug-related stimuli.

Relationships between cerebral blood flow velocities and arterial pressures during intra-aortic counterpulsation

OBJECTIVE

To determine the effects of intra-aortic counterpulsation (IABP) on cerebral blood flow velocity.

DESIGN

Prospective self-controlled study.

SETTING

University hospital surgical intensive care unit.

PARTICIPANTS

Nineteen cardiac surgical patients requiring perioperative IABP assistance.

INTERVENTIONS

Simultaneous recording of transcranial Doppler middle cerebral artery blood flow velocity and arterial pressure in response to changes in the magnitude of augmentation and trigger ratio.

MEASUREMENTS AND MAIN RESULTS

Instantaneous cerebral blood flow velocities correlated with arterial pressures during IABP (r = 0.650) at different magnitudes of augmentation and trigger ratios. The increase in arterial pressure during balloon inflation was associated with an increase in cerebral blood flow velocity, and the decrease in arterial pressure in response to balloon deflation was associated with a decrease in cerebral blood flow velocity that was dependent on the magnitude of augmentation. Different magnitudes of augmentation or trigger ratios had no effect on peak systolic cerebral blood flow velocity, mean cerebral blood flow velocity, mean arterial pressure, or the mean velocity-to-pressure ratio. Instantaneous cerebral blood flow velocity to arterial pressure ratios were lowest in response to balloon deflation at the time of pre-ejection.

CONCLUSIONS

IABP modified the phasic profile of cerebral blood flow to reflect the arterial pressure waveform without affecting mean cerebral blood flow velocity. Peak systolic cerebral blood flow velocity was maintained in augmented beats despite the decreased systolic arterial pressure associated with afterload reduction. The acute decrease in cerebral blood flow velocity at pre-ejection was balanced by increased cerebral blood flow velocity during balloon inflation in diastole.

Domestic violence awareness and prevalence in a first-year medical school class

OBJECTIVE

To determine knowledge about domestic violence (DV), the effectiveness of formal instruction about DV, and the prevalence of DV in a first-year medical school class.

METHODS

A general-knowledge survey of DV was given before and approximately 1 month after 3 hours of instruction provided by emergency medicine and internal medicine faculty. A previously validated scale, the Index of Spouse Abuse (ISA), was offered to determine baseline levels, of DV within the group. Differences in first-year medical student knowledge of facts about DV and differences in responses by men vs women were determined before and after the instruction.

RESULTS

In the pre-instruction series, 144 of 148 (97%) participated. After the instruction, 141 of the same 148 students participated (95%). The prevalence of DV against women was correctly identified by 45% of the students as "15-30%" prior to instruction, and 65% after instruction. The prevalence of DV against males was correctly identified as "0-15%" by 48% of the students prior to instruction, and 70% after instruction. Before instruction, 29% of the students knew that "DV rates are equal in different socioeconomic groups," vs 72% after instruction. Similarly, prior to instruction 58% of the students knew that the victim is not responsible for the abuse, and 84% knew this after instruction. Before instruction 14 (10%) of the students believed they were victims of DV in the past, representing 7% of the men and 13% of the women. Before instruction neither group believed they were present victims of DV. However, according to ISA scoring, 6% of the women were positive for violence in the past, and approximately 5% were positive for present violence. No men were positive for ISA-determined past or present violence.

CONCLUSION

Improvement in awareness was demonstrated after 3 hours of instruction in a first-year medical school class. There was DV among female medical students in this first-year class and self-reporting was not reliable. These results support instruction on DV for medical students.

Domestic violence in an inner-city ED

STUDY OBJECTIVE

To determine the prevalence of domestic violence (DV) for male and female ED patients and to determine the demographics of DV.

METHODS

The study design was a descriptive written survey of adults. We used the Index of Spouse Abuse (ISA), a previously validated survey tool. The study was set in an inner-city ED with approximately 75,000 patients annually, most of them indigent. Patients 18 years or older who were able to give consent were included. Patients were excluded if they had a language barrier, were a prisoner, or had never had a partner. All patients presenting during 31 randomly selected 4-hour shifts during July 1995 were considered for the study. DV was defined as either physical or nonphysical on the basis of ISA scoring. The prevalence was determined for present (in the preceding year) and past (more than 1 year ago) abuse. Four violence parameters were calculated for patients who had a partner at the time of presentation: present physical, present nonphysical, past physical, and past nonphysical. Only the "past" parameters were calculated for patients who had had a partner in the past but had no partner at the time of presentation. We used the chi2 test to determine individually significant predictors of the four parameters. Logistic-regression models were constructed to determine the significant predictors of DV. Associations among the present physical, present nonphysical, past physical, and past nonphysical abuse categories were determined with McNemar's test.

RESULTS

We enrolled 516 patients, 233 men and 283 women. On the basis of ISA scoring, 14% of men and 22% of women had experienced past nonphysical violence (P=.02, men versus women), and 28% of men and 33% of women had experienced past physical violence (P=.35). Of the 157 men and 207 women with partners at the time of presentation, 11% of men and 15% of women reported present nonphysical violence (P=.20), and 20% men and 19% of women reported present physical violence (P=.71). Using logistic-regression models, we determined that women experienced significantly more past and present nonphysical violence but not physical violence than men. For all four parameters, the victim's suicidal ideation and alcohol use were independently associated with DV. The victim's family history was strongly associated with past abuse. Using McNemar's test, we found that physical and nonphysical abuse were correlated in the past and present.

CONCLUSION

Using a validated scale, we found that the prevalences of physical DV for men and women are high and that they are not statistically different in this population. Using chi 2 testing, we found that women had experienced significantly more past nonphysical violence than men; using logistic regression we found that they experienced significantly more nonphysical violence (both past and present) than men. DV was frequently associated with suicidal ideation, alcohol use, and family history of violence.

Hazards associated with metalworking by artists

Metalworking is the constructive sculptural application of various technologic processes for producing art from ferrous and nonferrous metals. Self-employed artists and their workplaces are not protected by governmental agencies. We describe the techniques involved in metalworking processes and discuss the physical trauma and medical syndromes associated with each process, as well as safety, prevention, and treatment aspects of the basic syndromes.

Bioimpedance cardiac output measurements in patients with presumed congestive heart failure

OBJECTIVE

To describe preliminary ED experience with thoracic electrical bioimpedance (TEB) for evaluation of patients with complaints suggestive of congestive heart failure (CHF).

METHODS

A 6-month, prospective, observational study was performed using a convenience sample of patients with signs and symptoms consistent with CHF. Patients were excluded if they had received medication prior to arrival in the ED, if they were obese, and if they had unstable vital signs. They also were excluded if they were combative, refused to sign consent, or had invasive lines that did not allow for TEB lead placement. Patients also were excluded if the study could not be completed because the patient was taken from the department for a diagnostic test, or if there were no good follow-up records available 6-12 months after the patient's visit. The patient's physician was blinded to the output of the TEB monitor. Cardiac output (CO), stroke volume (SV), end-diastolic volume (EDV), thoracic fluid index (TFI), and acceleration index (ACI) were recorded at 5-minute intervals. Results were evaluated for the time intervals 0-5 minutes, 30-35 minutes, and 60-65 minutes.

RESULTS

Seven patients were included in the study. The echocardiographic diagnoses were hypertrophic cardiomyopathy (2 cases), dilated cardiomyopathy (2 cases), ischemic cardiomyopathy (1 case), right ventricular hypertrophy (1 case), and pericardial effusion (1 case). Significant changes were seen in all cardiac parameters, with variance from individual to individual.

CONCLUSIONS

Significant differences in TEB variables exist between patients who appear similar on initial examination in the ED. Changes noted on TEB may help to further elucidate physiologic differences. The clinical use of TEB-based hemodynamic measurements to guide presumed CHF patient management remains speculative.

Research funding in the four major emergency medicine journals

The objective of this survey was to determine the percentage of unfunded studies published in the four major emergency medicine journals and to examine the sources in funded studies. This study was a retrospective survey of all issues of the four general emergency medicine journals in 1994. Funding was categorized as public national, private, international, institutional, or unfunded. The total funding and sources were recorded for each of the four journals. Confidence intervals (CIs) were determined to compare the percent of funded versus unfunded articles. Overall, significantly more of the emergency medicine articles in the four journals were unfunded (63% unfunded [95% CI = 56.7-69.1]; 37% funded [95% CI = 30.9-43.3]). The sources of funding for each of the journals varied, with most being private (45%). In conclusion unfunded research remains a major source of emergency medicine literature in the four main emergency medicine journals.

Cost minimization analysis of various treatment options for surgical stage I endometrial carcinoma

PURPOSE

This study compares the payors' cost of treatment for surgical Stage I endometrial carcinoma with results of published clinical studies to determine which treatment most efficiently uses available resources.

METHODS AND MATERIALS

Six options for treatment of surgical Stage I endometrial carcinoma were selected for comparison. The treatment options were observation only, low-dose-rate brachytherapy (LDRB) (nonremote afterloading), LDRB and external beam radiation (EBRT), EBRT only, high-dose-rate brachytherapy (HDRB) only (three applications), and EBRT and HDRB (three applications). The literature was reviewed to obtain disease-free survival (DFS) rates corresponding to the treatment options chosen in surgical Stages IA, IB, and IC. Metaanalysis and sensitivity testing were performed on the collected clinical data. A typical midsized city in Medicare region IV was used as our representative payor cost basis.

RESULTS

Thirteen retrospective articles contained sufficient clinical information for analysis. Comparison of DFS between the observation, LDRB, and EBRT treatment groups was made for Stage IA; LDRB and EBRT for Stage IB; and LDRB, EBRT, LDRB +/- EBRT, LDRB + EBRT, and HDRB + EBRT for Stage IC. Meta-analysis failed to reveal statistically significant DFS between the respective treatment options within Stages IA, IB, or IC. The RVUs for each treatment option were LDRB, 21.7; EBRT, 117.1; EBRT + LDRB, 130.7; HDRB, 155.5; and EBRT + HDRB, 264.4. The DRG payment for LDRB is $2714.92. The calculated payor's cost for each treatment option was: LDRB, $3466.62; EBRT, $4053.03; EBRT + LDRB, $7238.55; HDRB, $5381.19; and EBRT + HDRB, $9153.14.

CONCLUSION

Our analysis reveals no statistically significant differences in DFS among the treatment options considered within each surgical stage. Observation appears to result in acceptable DFS with minimal cost in Stage IA. Low-dose-rate brachytherapy was the most cost-effective treatment in Stage IB, with no statistically significant difference in DFS between LDRB and EBRT. Although LDRB had inferior DFS compared to other treatment options in surgical Stage IC, this difference failed to reach statistical significance. Our analysis implies, excluding observation, that LDRB may be a more cost-efficient treatment than the other treatment options considered. Further studies stratifying for surgical stage and grade are needed to determine the optimal cost-effective treatment for this common malignancy.

A nurse with anaphylaxis to stone fruits and latex sensitivity: potential diagnostic difficulties to consider

BACKGROUND

There have been several recent reports describing a cross-reactivity between latex and antigens derived from a number of fruits, including those of the stone fruit family. The relationships between the allergic reactions to the antigens from these plant products are still being defined.

OBJECTIVE

To characterize the IgE reactivity of a patient who had anaphylactic reactions following the ingestion of several members of the stone fruit family (ie, plum, peach, and nectarine) and had a positive clinical history for latex allergy.

METHODS

The patient's serum was tested for the presence of specific IgE for latex, stone fruits, and a panel of other foods reported to be cross-reactive with latex. Prick testing was also performed with freshly prepared extracts from the implicated fruits. Finally, the immunochemical relationship between this patient's fruit and latex sensitivity was investigated by RAST inhibition.

RESULTS

The patient had strongly positive skin tests to the freshly prepared fruit extracts but the in vitro food-specific IgE tests were equivocal or very low positive. In vitro latex-specific IgE tests were strongly positive. The stone fruit extracts were shown to be inhibitors of the patient's latex specific IgE by RAST inhibition.

CONCLUSION

Skin testing with freshly prepared fruit extracts was more sensitive than the in vitro tests with this patient. The inhibition data support an immunochemical relationship between the patient's latex allergy and sensitivity to stone fruits.

Combining operant-baseline-derived conditioned excitors and inhibitors from the same and different incentive classes: an investigation of appetitive-aversive interactions

The dynamics of appetitive-aversive interaction theory were assayed in an experiment where excitors and inhibitors from the same and different incentive classes were compounded. Excitatory and inhibitory incentive properties acquired by the discriminative stimuli resulted from the reinforcement differences between components of four-component multiple training schedules, with the influence of competing peripheral responses factored into the design. Rats' barpressing was maintained in tone and in click by food or free-operant shock avoidance; extinction was programmed in click-plus-light and in the simultaneous absence of tone, click, and light. In Test 1, an excitor that occasioned operant responding and an inhibitor that occasioned response cessation were compounded. Here, compounding an inhibitor with an excitor from the same incentive class reduced responding significantly more than did compounding an inhibitor with an excitor from the other incentive class. In Test 2, the compounds consisted of elements that individually occasioned operant responding. Here, compounding stimuli that were excitors from different incentive classes appeared to create reciprocal inhibition that counteracted the additive effects produced when these stimuli were excitors from the same incentive class. Predictions from appetitive-aversive interaction theory and Weiss' two-factor model of stimulus control were confirmed within this experimental design, where all conditioning was a by-product of the behavioural contingencies programmed on the operant baselines.

Effect of individual and work characteristics of EMTs on vital sign changes during shiftwork

This study examines the effects of demographics, lifestyle, and work characteristics on burnout in EMTs, and then determines the interaction of various EMT risk factors on cardiovascular changes. In phase 1, EMTs voluntarily completed a demographic data sheet and the Masslach Burnout Inventory (MBI). The MBI results were broken down into subgroups of Emotional Exhaustion (EE), Depersonalization (DP), and Personal Achievement (PA); these were then compared to national averages. Subgroup analysis was performed on the basis of sex, race, marital status, years with the service, smoking, and caffeine drinking habits. In phase 2, EMTs carried logbooks for 1 month, during which they recorded preshift and postshift blood pressure and pulse. Other information recorded for each shift was the amount of caffeine and cigarettes used, the number of advanced life support (ALS) and total runs, and whether the shift worked was day or night. Per-shift average caffeine use, average number of ALS and total runs, and average cross-shift changes in MAP (deltaMAP) and P (deltaP) were calculated for each EMT. The deltaMAP and deltaP were compared for discrete variables (sex, race, training levels, smoker v nonsmoker, marital status, and shift worked) and continuous variable (age, years with the service, total runs, ALS runs, and MBI subscale scores). Continuous variables were split into two groups using the median as a separator. Differences were detected at P < .05 by confidence interval analysis. Sixty-nine EMTs enrolled in phase 1. The EMTs scored significantly lower on the PA scale than the national average (28.1 v 34.6). The low PA score was only seen in the subgroup of EMTs with the service longer than 3 years (26.1 v 30.0). Forty EMTs completed phase 2 of the study. There were no significant differences in deltaMAP detected in any subgroup. There was a significant difference in deltaP based on marital status (single, -4.5 v married, 2.6), and age (younger than 32, -4.5 v older than 32, 0.6). There were no other detected deltaP changes. In conclusion, these results showed that PA is lower in our EMTs than in the general population; EMTs with the service longer than 3 years had the lowest values. There were no significant preshift to postshift changes in blood pressure in any subgroup. There was a statistically significant preshift to postshift decrease in pulse in unmarried EMTs and in those younger than 32 years of age. These results indicate little variation in stress between EMTs and the general population and do not indicate a need for more intensive intervention programs for the management of heart rate or pulse.

Detection of stroke during cardiac operations with somatosensory evoked responses

OBJECTIVES

The objectives of this study were to determine if monitoring of intraoperative somatosensory evoked potentials could be used to detect stroke during cardiac operations and to establish indicators of cerebral ischemia based on changes in these potentials.

METHODS

Twenty-five patients undergoing cardiac operations underwent preoperative and postoperative neurologic examinations as well as intraoperative recording of somatosensory evoked potentials. Detailed analysis of the waveforms of these potentials was performed.

RESULTS

Two of the 25 patients had intraoperative strokes. These patients and only these patients had changes in their somatosensory evoked potentials during the operation suggesting cerebral ischemia. The unilateral disappearance of the cortical somatosensory evoked potential waves correlated significantly with the clinical outcome of stroke (p < 0.004). Ischemic changes were detected in real time and were related to the removal of the aortic crossclamp in one patient and to the initiation of cardiopulmonary bypass in the other.

CONCLUSIONS

Somatosensory evoked potentials can detect intraoperative stroke during cardiac operations. Acute, unilateral decreases in amplitude of the cortical potential are more useful than changes in latency in detecting intraoperative stroke.

Cocaine self-administration increased by compounding discriminative stimuli

Presenting independently established discriminative stimuli in compound can substantially increase response rates under food and shock-avoidance schedules. To determine whether this effect extends to drug self-administration, rats were trained to press a lever to receive cocaine intravenously. A tone and a light were independently established as discriminative stimuli for cocaine self-administration, then presented in combination in a stimulus-compounding test. Compared to tone and light alone, the tone-plus-light compound stimulus increased responding approximately three-fold when cocaine was withheld during testing, and it increased drug intake approximately two-fold when cocaine was made available during testing. Compounding did not increase responding after training in a truly random control condition where tone and light were presented uncorrelated with the availability of cocaine. The results obtained with this animal model of drug abuse define conditions under which combinations of environmental stimuli might substantially increase human drug use.

Transmembrane-deletion mutants of the membrane-type matrix metalloproteinase-1 process progelatinase A and express intrinsic matrix-degrading activity

Membrane-type matrix metalloproteinase-1 (MT-MMP-1) has been proposed to play a critical role in regulating the expression of tissue-invasive phenotypes in normal and neoplastic cells by directly or indirectly mediating the activation of progelatinase A. To begin characterizing MT-MMP-1 structure-function relationships, transmembrane-deletion mutants were constructed, and the processing of the zymogens as well as the enzymic activity of the mature proteinases was analyzed. We now demonstrate that pro-MT-MMP-1 mutants are efficiently processed to active proteinases following post-translational endoproteolysis immediately downstream of an Arg108-Arg-Lys-Arg basic motif by a proprotein convertase-dependent pathway. The secreted form of active MT-MMP-1 not only displays an N terminus identical with that described for the processed wild-type enzyme at Tyr112 (Strongin, A. Y., Collier, I., Bannikov, G., Marmer, B. L., Grants, G. A., and Goldberg, G. I. (1995) J. Biol. Chem. 270, 5331-5338), but also directly mediated progelatinase A activation via a two-step proteolytic cascade indistinguishable from that observed with intact cells. Furthermore, although the only function previously ascribed to MT-MMP-1 is its ability to act as a progelatinase A activator, purified transmembrane deletion mutants also expressed proteolytic activities against a wide range of extracellular matrix molecules. Given recent reports that MT-MMP-1 ectodomains may undergo intercellular transfer in vivo (Okada, A., Bellocq, J.-P., Rouyer, N., Chenard, M.-P., Rio, M.-C., Chambon, P., and Basset, P. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 2730-2734), our data suggest that soluble forms of the proteinase confer recipient cells with the ability to not only process progelatinase A, but also directly degrade extracellular matrix components.

Beat-to-beat augmentation of left ventricular function by intraaortic counterpulsation

BACKGROUND

Measuring the effects of intraaortic balloon counterpulsation (IABP) in single cardiac beats may permit an improved understanding of the physiologic mechanisms by which IABP improves the circulation. The objective of the study was to use trans- esophageal echocardiography in combination with hemodynamic measurements to test the hypothesis that IABP improves global left ventricular systolic function selectively in the IABP-augmented cardiac beats by acutely decreasing left ventricular afterload.

METHODS

Twenty-seven studies in which the IABP-to-R wave trigger ratio was serially changed from 1:1, 1:2, 1:4, 0:1 (IABP off) and back to 1:1 were performed in 20 anesthetized cardiac surgical patients during IABP support. Left ventricular short-axis end-diastolic cross-sectional area, end-systolic area, mean end-systolic wall thickness, and ejection time were measured by transesophageal echocardiography at the midpapillary muscle level. Aortic pressure was measured simultaneously from the central lumen of the intraaortic balloon catheter. These measurements were used to calculate the fractional area change, end-systolic meridional wall stress, and heart rate-corrected velocity of circumferential fiber shortening. The echocardiographic and hemodynamic parameters of left ventricular preload, afterload, and systolic function immediately after balloon deflation (IABP-augmented cardiac beats) were compared to the parameters measured during nonaugmented cardiac beats to determine the beat-to-beat effects of IABP on left ventricular function.

RESULTS

IABP-augmented cardiac beats had a decreased systolic arterial pressure and end-systolic meridional wall stress and increased diastolic blood pressure, fractional area change, and velocity of circumferential fiber shortening compared to nonaugmented cardiac beats. IABP did not cause significant beat-to-beat changes in heart rate, pulmonary artery diastolic pressure, or central venous pressure. The improvement in left ventricular systolic function associated with IABP-augmented cardiac beats correlated with the decrease in end-systolic meridional wall stress for that cardiac beat.

CONCLUSIONS

Beat-to-beat echocardiographic and hemodynamic measurements performed in anesthetized cardiac surgical patients during IABP support demonstrated improved left ventricular systolic function and decreased left ventricular systolic wall stress in the cardiac beats immediately after balloon deflation. The relationship between left ventricular systolic function and left ventricular systolic wall stress during IABP support suggests that afterload reduction was an important mechanism by which IABP instantaneously improved circulatory function in anesthetized cardiac surgical patients.

Human immunodeficiency virus infection and multilocular thymic cysts

PURPOSE

Pathologic changes of the thymus, often seen in children with the human immunodeficiency virus (HIV), reflect direct invasion by the virus, followed by involution of the gland. A previously unknown form of thymic response to HIV infection, that of a multilocular thymic cyst, is reported.

MATERIALS AND METHODS

Findings were examined in three HIV-positive patients, two children and one adult first seen with large thymic masses.

RESULTS

All three had large, septate low-attenuation areas at computed tomography consistent with multilocular thymic cysts. The cystic nature of the lesions was confirmed with magnetic resonance imaging in two. Histopathologic examination, performed in two instances, helped establish the diagnosis. All patients remained in clinically stable condition. They all had parotid gland enlargement and lymphocytic interstitial pneumonia.

CONCLUSION

Multilocular thymic cysts are probably another manifestation of the diffuse infiltrative lymphocytosis syndrome, usually associated with a milder course of acquired immunodeficiency syndrome.

Syphilis screening in out-of-hospital care

To estimate the rates of syphilis infection in inner-city patients managed by prehospital providers, a convenience sampling of prehospital patients who had intravenous lines initiated was screened for syphilis over a nine-month study period from February 1992 through October 1992. In a university-affiliated inner-city emergency department served by a city ambulance company, patients 18 years of age or older transported via ambulance who had had intravenous lines initiated at the scene or en route had a Venereal Disease Research Laboratory (VDRL) and microhemagglutination-Treponema pallidum (MHA-TP) drawn and performed by the state laboratory as a routine serological test. If the results were reactive with no previous history of syphilis recorded in the state registry, the state health department and/or one of the authors of this study contacted the patient for follow-up treatment. Age, race, sex, and diagnostic category (medical, surgical/obstetric, or neuropsychiatric) were recorded. Results were checked with the state syphilis registry. Latent syphilis was defined as a reactive VDRL and MHA-TP with no prior history of infection or record of infection in the state syphilis registry. Chi-squared test was used in statistical analysis for comparisons among ages, races, and sexes, with P > .05 considered significant. Three hundred two subjects 18 years of age and older consenting to a screening VDRL and MHA-TP had serum drawn. Two hundred seventy-nine patients were enrolled in the study after 23 patients were excluded because of improper data collection or insufficient serum collection. There were 174 men (63%) and 105 women (37%), with 73 white (26%) and 199 African-Americans (71%).(ABSTRACT TRUNCATED AT 250 WORDS)