Penetrating cardiac trauma at an urban trauma center: a 22-year perspective

This is a report of a 22-year experience with penetrating cardiac trauma at a single urban Level I trauma center. We conducted a retrospective chart review supplemented by computerized patient log. Comparisons of mortality between Period 1 (1975-1985; 113 patients) and Period 2 (1986-1996; 79 patients) were by chi2 or Fisher's exact tests. Statistical significance was defined as P < or = 0.05. From 1975 to 1996, 192 patients (mean age, 32 years; 88% male) with penetrating cardiac stab wounds (68%) or gunshot wounds (32%) were treated. The most common initial clinical presentation was cardiac tamponade, and most patients (54%) were hypotensive (systolic blood pressure 30-90 mm Hg). The most common initial intervention in the emergency center was tube thoracostomy. The use of pericardiocentesis as a diagnostic and therapeutic modality in the emergency center virtually disappeared in Period 2, as compared with Period 1. Since 1994, surgeon-performed cardiac ultrasound has been performed and has correctly diagnosed hemopericardium in 12 patients (100% survival). The overall mortality for all patients during the 22-year study interval was 25 per cent and was not significantly different between Period 1 (27%) and Period 2 (22%). The mortality associated with gunshot wounds was increased compared with that of stab wounds. Similarly, mortality for patients who arrested in the emergency center was increased compared with those patients who did not arrest. We conclude: 1) cardiac tamponade is the most common presentation in patients with cardiac wounds; 2) pericardiocentesis in the emergency center has essentially disappeared; 3) surgeon-performed ultrasound of the pericardium should improve survival of future patients who are normotensive or mildly hypotensive; 4) over the last 11 years, there has been a substantial decrease in mortality in patients with stab wounds and a statistically significant decrease in arrested patients; and 5) overall mortality for penetrating cardiac trauma has not changed during the 22-year interval.

Latency alterations of the auditory brainstem response in audiogenic seizure-prone Long-Evans rats

Audiogenic seizure susceptibility in the normally seizure-resistant Long-Evans rat may result from altered processing in the auditory pathway. Representative waveform latencies of the auditory brainstem responses (ABR) were recorded to examine generator alterations at different levels of the auditory neuraxis. Male Long-Evans rats primed for audiogenic seizures (AGS) on PND 14 with a 10 kHz pure tone at 120 dB SPL for 8 min were tested for AGS on PND 28 with 120 dB SPL continuous white noise. Primed subjects displayed wild running culminating in clonic convulsions. Following behavioral testing at 4-6 months, vertex recordings of ABR waves Ia-VI were made in anesthetized subjects using pure tone stimulus bursts. AGS subjects showed marginally elevated ABR thresholds. Shorter ABR wave latencies were elicited in AGS subjects for peripheral and central auditory components with stimulus intensities above 50 dB PeSPL at 8 and 40 kHz. Interpeak intervals were reduced for waves Ia-V and III-V in AGS subjects. These results reveal that intense sound stimulation during a sensitive period of development later reduces processing time at higher intensity levels.

Estrogen treatment and age effects on auditory brainstem responses in the post-breeding Long-Evans rat

The auditory brainstem response (ABR) was recorded from 20-month-old Long Evans hooded female rats to determine if latency reductions occur from estrogen replacement. The ABR in these post-breeding age rats was also examined for reductions in response latencies as a function of adult age. Tone pip stimuli (8 and 40 kHz) were presented at 21, 51, or 81 s(-1). Aging control and ovariectomized animals showed slower response latencies for waves Ib-VI than young adults for 8 and 40 kHz stimulation at 21 s(-1). Increased stimulus rate resulted in longer latencies for all waves at 20 months. In contrast to hormone treatment effects in young adults, ABR latencies in post-breeding age estrogen-treated animals were not reduced, consistent with a general decrease in CNS responsiveness to estrogen steroids associated with age. The results also suggest that sensorineural modifications in the auditory system which prolong ABR latencies can occur early in the aging process of adult female subjects.

Modifying risk for extracorporeal circulation: trial of four antiinflammatory strategies

BACKGROUND

Despite recent rediscovery of beating heart cardiac surgical techniques, extracorporeal circulation remains appropriate for most heart operations. To minimize deleterious effects of cardiopulmonary bypass, antiinflammatory strategies have evolved.

METHODS

Four state-of-the-art strategies were studied in a prospective, randomized, preoperatively risk stratified, 400-patient study comprising primary (n = 358), reoperative (n = 42), coronary (n = 307), valve (n = 27), ascending aortic (n = 9), and combined operations (n = 23). Groups were as follows: standard, roller pump, membrane oxygenator, methylprednisolone (n = 112); aprotinin, standard plus aprotinin (n = 109); leukocyte depletion, standard plus a leukocyte filtration strategy (n = 112); and heparin-bonded circuitry, centrifugal pumping with surface modification (n = 67).

RESULTS

Analysis of variance, linear and logistic regression, and Pearson correlation were applied. Actual mortality (2.3%) was less than half the risk stratification predicted mortality (5.7%). The treatment strategies effectively attenuated markers of the inflammatory response to extracorporeal circulation. Compared with the other groups the heparin-bonded circuit had highly significantly decreased complement activation (p = 0.00001), leukocyte filtration blunted postpump leukocytosis (p = 0.043), and the aprotinin group had less fibrinolysis (p = 0.011). Primary end points, length of stay, and hospital charges, were positively correlated with operation type, age, pump time, body surface area, stroke, pulmonary sequelae, predicted risk for stroke, predicted risk for mortality, and risk strata/treatment group interaction (p = 0.0001). In low-risk patients, leukocyte filtration reduced length of stay by 1 day (p = 0.02) and mean charges by $2,000 to $6,000 (p = 0.05). For high-risk patients, aprotinin reduced mean length of stay up to 10 fewer days (p = 0.02) and mean charges by $6,000 to $48,000 (p = 0.0007).

CONCLUSIONS

These pharmacologic and mechanical strategies significantly attenuated the inflammatory response to extracorporeal circulation. This translated variably into improved patient outcomes. The increased cost of treatment was offset for selected strategies through the added value of significantly reduced risk.

Validation of surgeon-performed emergency abdominal ultrasonography in pediatric trauma patients

BACKGROUND/PURPOSE

The focused assessment for the sonographic evaluation of trauma patients (FAST) in adults is effective in detecting intraperitoneal and intrapericardial fluid and can be performed quickly by surgeons in the emergency department (ED). The authors sought to validate the accuracy of FAST performed by surgeons during ED resuscitation of pediatric trauma patients.

METHODS

Patients were assigned to one of three groups based on standard clinical criteria: immediate surgery, abdominal computed tomography (CT), or observation alone. FAST was then performed in the ED by a surgery resident (postgraduate year 3 or higher) or an attending trauma surgeon. Four views were used to assess the possible presence of fluid in the pericardial, subphrenic, subhepatic, and pelvic spaces. Time needed to conduct FAST was noted. Presence of peritoneal or pericardial fluid by FAST was compared with that determined by CT or surgery. Sensitivity, specificity, and predictive values were calculated. For those who did not undergo CT or surgery, FAST findings were compared with the clinical course.

RESULTS

Technically adequate studies could be performed on 192 of 196 eligible children. Their ages ranged from 3 months to 14 years (mean, 6.9 years); 119 were boys (62%), and 188 (98%) had sustained a blunt injury. FAST was performed in a mean time of 3.9 minutes (range, 1-17 minutes). All FAST examinations were reviewed by our senior surgeon-sonographer (GSR). Interrater agreement between the performing and reviewing surgeon-sonographer was 100%. Sixty (31%) patients underwent either abdominal CT (n = 56; mean Injury Severity Score (ISS), 9.6) or immediate operation (n = 4; mean ISS, 18.8). Of the 10 patients with verified presence of intraperitoneal fluid, eight had positive and two had false-negative FAST examination results. Of the 50 patients with verified absence of intraperitoneal fluid, none had a positive FAST (ie, no false-positives); sensitivity was 80%; specificity, 100%; predictive value positive, 100%; predictive value negative, 96%. None of the 132 patients followed up clinically without CT or surgery (mean ISS, 4.5) had fluid documented by FAST, and all did well.

CONCLUSIONS

The focused assessment for the sonographic evaluation of pediatric blunt trauma patients performed by surgical residents and attendings in the ED rapidly and accurately predicted the presence or absence of intraperitoneal fluid. The FAST is a potentially valuable tool to rapidly prioritize the need for laparotomy in the child with multiple injuries and extraabdominal sources of bleeding.

Induction of magnetic resonance-visible lipid in a transformed human breast cell line by tetraphenylphosphonium chloride

Proton magnetic resonance spectroscopy (1H MRS) and DNA flow cytometry were used to monitor the effects of the cationic lipophilic phosphonium salt and potential antineoplastic agent tetraphenylphosphonium chloride (TPP) on the transformed human breast cell line HBL-100. TPP treatment for 48 hr was cytostatic at low concentrations and cytotoxic at higher concentrations with an IC50 of 55 microM as measured by Trypan blue exclusion. At micromolar concentrations, TPP caused a significant increase in the methylene MR signal arising from mobile lipid as measured by the ratio of the lipid CH2 peak height to either the CH3 peak height (internal referencing) or the peak height for p-aminobenzoic acid (PABA) as an external reference in a co-axial capillary within the sample. Over the same concentration range, TPP caused a slowing of passage through S phase as demonstrated by a significant depletion of cells in G2/M phase with a concurrent but non-significant increase in cells in S. Time-dependent increases in MR-visible lipid were observed with 2 microM TPP treatment, and the removal of TPP from the culture medium caused no significant reduction in mobile lipid. Two-dimensional 1H-1H COSY spectra of TPP-treated HBL-100 cells revealed concentration-dependent increases in cross-peak volume ratios arising from lipid acyl chains relative to both internal (lysine, polyamines) and external (PABA) standards. Increases in choline and glycerophosphocholine cross-peak volume ratios were observed, indicating that the catabolism or rearrangement of phospholipids may be responsible for the observed MR-visible lipid increases.

Auditory brainstem responses after ovariectomy and estrogen replacement in rat

Previous work has suggested possible influences of ovarian hormones on evoked potentials in the auditory system. The aim of this project was to study the effects of ovariectomy and subsequent administration of estrogen replacement on the auditory brainstem response and the middle latency response. Groups of 90 day-old Long-Evans hooded rats were anesthetized for bilateral ovariectomies (ovex) and recordings made 3 weeks later. During the week prior to recordings some ovariectomized groups received subcutaneous injections of 10, 100 or 500 micrograms/kg Premarin in peanut oil, and other unoperated animals received vehicle injections. Recordings from vertex/chin using needle electrodes and pure tone stimulus parameters were made under Rompun/Ketamine. The results using 40 kHz tone stimuli showed that mean latencies for ovex animals were longer than animals in the 100 micrograms/kg Premarin group for waves 1a, 1an, 1b, 11, 111, 111n, and 1V/V. Other posthoc comparisons at 40 kHz stimulation revealed differences between control and 100 micrograms/kg Premarin groups for latencies of waves 1b, 1bn, 11 and 111. Latency reduction appeared for waves 1b, 1bn, 11 and 111 for the 10 ovex group, but only at wave 11 for the 500 ovex group, compared to ovex-only animals. Data from 8 kHz stimulation also demonstrated significant differences between the ovex and ovex 100 groups at waves 1bn and Vn. Observations of interpeak latency differences, especially between waves 1a and 11, suggested central as well as cochlear involvement in hormone action.(ABSTRACT TRUNCATED AT 250 WORDS)

Rate and frequency interactions in the auditory brainstem response of the adult rat

Tone pip stimuli were used at different repetition rates to examine influences upon auditory brainstem response components. Rate increases to 80.1/s result in significant latency increases in waves IV and V at all test frequencies. Rate effects occur in rostral brainstem response components which show frequency related latencies different from wave I. Amplitude measures decline at higher repetition rates for waves I and IV at most test frequencies. Rate effects are most pronounced at 8 kHz stimulation which is around the optimal behavioral frequency in rat. At higher rates the second peak of wave I is enhanced at 8 kHz, whereas the third peak of wave I at 40 kHz disappears. These results demonstrate that tone-specific stimuli provide sensitive measures of latency, amplitude and wave morphology of components of the auditory brainstem response as a function of stimulus repetition.

Comparison of SSPL90 selection procedures

Recommended SSPL90 values were determined at 500, 1000, and 2000 Hz for 16 subjects with mild-to-moderate sensorineural hearing losses using six different selection procedures, including an Upper Limit of Comfortable Listening (ULCL) and threshold-based procedure by Cox (1988), a threshold-based procedure by Seewald and Ross (1988), and loudness discomfort procedures by Berger (1988), McCandless and Lyregaard (1983), and Hawkins et al (1987) and Libby (1985). Statistically significant differences were found among the procedures at 500 and 2000 Hz. Analysis of individual data showed that while some subjects obtained similar recommended SSPL90s across the procedures, others showed dramatically different values.

Effect of reference microphone location and loudspeaker azimuth on probe tube microphone measurements

The effects of loudspeaker azimuth and reference microphone location on probe tube microphone measures were assessed. The real ear unaided response (REUR), real ear aided response (REAR), and real ear insertion response (REIR) were obtained on a KEMAR. Aided measures were obtained with both a behind-the-ear and an in-the-ear hearing aid. All three measurements were affected by changes in the loudspeaker azimuth and reference microphone location. Responses obtained with a 90 degree loudspeaker azimuth or with the reference microphone located at-the-ear revealed greater disparity than those obtained under other conditions. Most of the differences occurred at frequencies above 2000 Hz, with measurements utilizing the behind-the-ear hearing aid showing greater dispersion. These results suggest that the location of the loudspeaker and the reference microphone are important variables when utilizing probe tube microphone measurements.

Comparisons among SPLs in real ears, 2 cm3 and 6 cm3 couplers

Sound pressure levels (SPLs) were measured in the ear canals of 30 adult subjects with standard audiometric earphones (TDH-39) and insert earphones (Etymotic ER-3A) and compared to those generated in 2 cm3 and 6 cm3 couplers. Transfer functions are shown for real ear to 2 cm3 coupler, real ear to 6 cm3 coupler, 6 cm3 to 2 cm3 coupler, and dB HL under standard earphones to 2 cm3 coupler SPL. In general, the data agreed rather well with published transfer functions that in most cases were derived by adding together a series of partial transfer functions from various studies. The conversion values from dB HL to 2 cm3 coupler SPL could be useful in selection of certain hearing aid parameters, but the intersubject variability may limit their usefulness somewhat.

Auditory brainstem responses to tonal stimuli in young and aging rats

The auditory brain stem response (ABR) was studied in young adult and aged rats using 3,8 and 40 kHz tone pips. The expected inverse relationship between frequency and latency was observed in the younger group for waves I, II and III, while the response to the highest frequency stimulus had the longest latency at wave V. Absolute latencies for waves I through V each showed age-related increments with more pronounced changes occurring to 3 and 40 kHz stimuli than to the frequency of maximum sensitivity (8 kHz). Threshold increases with age for the highest frequency approximately doubled those for the lower frequencies. Examination of interpeak intervals (IPI) I-III, III-V and I-V revealed aging effects. The largest IPI I-V increment occurred to 3 kHz stimulation which reflects changes at both I-III and III-V sub-intervals. These results demonstrate electrophysiological correlates of aging due to transformations in the peripheral auditory system coupled with alterations in brainstem auditory pathways.

Use of probe tube microphone measurements in hearing aid selection for children: some initial clinical experiences

Some initial experiences are described in which ear canal probe tube microphone measurements are used to determine hearing aid settings for children. Decisions are based upon ideas developed by Seewald and Ross (in Amplification for the Hearing Impaired, New York: Grune & Stratton, 1988: 213-267) and Seewald, Ross, and Stelmachowicz (J Acad Rehab Aud 1987;20:25-37) in which the long term spectrum of speech is amplified to desired sensation levels. Case results from four children are used to demonstrate the application and usefulness of the procedure.

A comparison of three HA-1 couplers

The use of 2-cm3 couplers for measuring the output of an ER-3A earphone has been recommended. The purpose of this study was to compare the acoustic output of three commonly available couplers and to study the intra- and inter-examiner reliability with which those measurements may be performed. While the repeatability of measurements, at least for clinical purposes, was good even for hand-held coupling of the earphone to the couplers, differences between couplers were observed. These differences were influenced by the positioning of the sound-outlet orifice relative to the interior, top wall of the couplers' cavities. A recommendation for 2-cm3 coupler calibration of the ER-3A earphone using a commonly available adapter was made.

Development of auditory brainstem response to tone pip stimuli in the rat

The course of development of the auditory brainstem response (ABR) in rat was examined. Pure tone pip stimuli of 3, 8 and 40 kHz at intensities up to 106 dB sound pressure level peak equivalent were presented to anesthetized rats on postnatal days (PND) 9, 10, 12, 14, 16, 20, 24, 36, 70 and 96. The peak-to-peak amplitude and the order of appearance of each wave was examined at each stimulus parameter. The first response to presentation of an auditory stimulus was observed on PND 12. This response was demonstrated to be of non-neural origin and presumed to be a summating potential representing hair cell function in the cochlea. The first neural responses, observed on PND 14, to 3- and 8-kHz tones only, appeared as two or more waves. High-frequency (40 kHz) tones did not elicit any substantive neural response on PND 14, but neural activity to this stimulus was observed consistently by PND 16. By PND 20, 4 waves were present consistently at all test frequencies, and by PND 36 the full adult complement of 5 vertex positive waves was recorded. The frequency-dependent sequential appearance of waves during development lends support to data charting the development of frequency mapping in the cochlea. The amplitude of waves I and II at 8 kHz decreased as the animal matured, while waves III-V generally showed an initial increase in amplitude at all test frequencies through PND 24 followed by a gradual amplitude decrease to adult levels. Possible sources for developmental changes in amplitude are discussed.

Delayed feedback audiometry: reliability of repeated measures

The test-retest reliability of hearing thresholds at 1000 Hz measured by a delayed auditory feedback procedure was compared with the reliability of thresholds obtained with voluntary responses to the same signal in 10 adults with normal hearing sensitivity. Thresholds for each procedure were obtained three times on each of 5 different days. Although the delayed feedback procedure yielded estimates of threshold which averaged 4.6 dB greater than those estimated by voluntary responses (p less than 0.05), there was no evidence that experience over time resulted in a change for the poorer in the precision of the test.

Stimulus artefact reduction systems for the TDH-49 headphone in the recording of auditory evoked potentials

Standard audiometric transducers, such as the TDH-49, produce an electrical artefact which interferes with the recording of the early auditory evoked potentials. The sources of these artefacts have been identified as the capacitive and inductive coupling of the transducer and its leads to the recording electrodes. Artefacts were recorded using an artificial head with an M2-Cz electrode array for 500- and 3-kHz tone pips and positive, negative, and alternating polarity clicks at Peak Equivalent Sound Pressure Levels from 60 dB (positive click and 3-kHz tone pip) to 90 dB (alternating polarity click). The artefacts grew linearly with increases in intensity. Shifts in the Visual Detection Threshold of the artefacts produced by various conditions of shielding the transducer and its leads were explored. Acceptable reductions in artefact magnitude were obtained by enclosing the transducer in either an aluminium or mu-metal case connected through a braided-wire shield of the transducer leads to earth ground. Lesser reductions were achieved by the use of antiphase cancellation. The combination of the latter and the aluminum and mu-metal cases did not produce greater shifts in the visual detection threshold than the use of the aluminum and mu-metal cases alone. The fabrication of a pair of shielded enclosures is described and data are presented which show that they do not adversely affect the acoustic output of the headphones.

Pure tone delayed auditory feedback: effect of instructions

This study compared the effect of instructions to the subject upon key tapping performance with pure-tone delayed auditory feedback. One set of instructions stressed the importance of maintaining tapping rate whereas a second set emphasized consistency of the pattern. A third set stressed rate and pattern equality. The results lead to the recommendation that instructions stress equally both rate and pattern consistency.

Combining auditory and visual stimuli in the adaptive testing of speech discrimination

This investigation determined the feasibility of using both auditory and visual stimuli in the adaptive testing of speech discrimination. Thirty-six adults with normal hearing and vision were subjects. Using the adaptive methodology known as the Doublet technique, speech-discrimination testing using monosyllabic word lists from the Northwestern University Auditory Test No. 6 (NU-6) (Tillman and Carhart, 1966) was performed at the target levels of 29.3 and 70.7% for both auditory-only and auditory-visual conditions. The results indicated that a specific discrimination score could be obtained under more adverse listening conditions with the addition of visual cues. The contribution of visual cues was constant for the two target scores. The adaptive technique at the 29.3 and 70.7% targets was reliable for both the auditory-only and auditory-visual conditions. Constant level testing showed good agreement with the adaptive technique for the auditory-visual condition. In conclusion, the use of standard error calculations is useful in determining measurement errors and the effects of an aural rehabilitation program.

Pure tone delayed auditory feedback. Effect of hearing loss on disruption of tapping performance

Pure tone delayed auditory feedback audiometry was administered to 20 veterans with normal hearing at 1 kHz and a sensorineural hearing loss associated with noise exposure at 4 kHz. Absolute and relative time errors as well as pattern errors were analyzed for the group and for each individual. Mean data showed no difference between error measures for the two frequencies. However, individual data revealed that errors in the subjects' performance occurred at a level slightly closer to threshold at the frequency with the hearing loss (4 kHz) than at the frequency at which hearing was normal (1 kHz).

Filter effect of earmold venting: comparison of electroacoustic and psychoacoustic methods of evaluation

The filter effect of venting an earmold was evaluated by measuring the coupler-acoustic and threshold responses to open versus closed earmolds. In the coupler-acoustic technique the effect of venting was determined by measuring the output of the experimental earmolds seated on a modified 2-cc coupler with a specified signal impressed upon the earphone. The real ear threshold technique called for the determination of threshold by five listeners for the same earphone-earmold system. The data indicated that the difference between the coupler and threshold measures were of the same order of magnitude as the difference seen by other investigators reporting coupler and real ear-probe tube microphone measures. It was concluded that the threshold technique provides the same general description of the effects of venting an earmold as does the probe tube technique and should thus provide a useful method for determination of the filter effects produced by the venting of an earmold.