Faculty Bibliography

OBJECTIVES/OBJECTIVE:Emergency medicine in low- and middle-income countries (LMICs) is hindered by lack of research into patient outcomes. Chief complaints (CCs) are fundamental to emergency care but have only recently been uniquely codified for an LMIC setting in Uganda. It is not known whether CCs independently predict emergency unit patient outcomes. METHODS:Patient data collected in a Ugandan emergency unit between 2009 and 2018 were randomized into validation and derivation data sets. A recursive partitioning algorithm stratified CCs by 3-day mortality risk in each group. The process was repeated in 10,000 bootstrap samples to create an averaged risk ranking. Based on this ranking, CCs were categorized as "high-risk" (>2× baseline mortality), "medium-risk" (between 2 and 0.5× baseline mortality), and "low-risk" (<0.5× baseline mortality). Risk categories were then included in a logistic regression model to determine if CCs independently predicted 3-day mortality. RESULTS:Overall, the derivation data set included 21,953 individuals with 7,313 in the validation data set. In total, 43 complaints were categorized, and 12 CCs were identified as high-risk. When controlled for triage data including age, sex, HIV status, vital signs, level of consciousness, and number of complaints, high-risk CCs significantly increased 3-day mortality odds ratio (OR = 2.39, 95% confidence interval [CI] = 1.95 to 2.93, p < 0.001) while low-risk CCs significantly decreased 3-day mortality odds (OR = 0.16, 95% CI = 0.09 to 0.29, p < 0.001). CONCLUSIONS:High-risk CCs were identified and found to predict increased 3-day mortality independent of vital signs and other data available at triage. This list can be used to expand local triage systems and inform emergency training programs. The methodology can be reproduced in other LMIC settings to reflect their local disease patterns.

Average auditory evoked potentials (AEPs) to amplitude modulated (AM) linear voltage ramps within a limited intensity range were investigated in a group of 4 subjects. Increasing linear voltage ramps evoked the familiar vertex potential; the average AEP to decreasing ramps was difficult to measure because of its small amplitude. The amplitude of the average AEP to increasing ramps depended on the tone that preceded it. The average amplitude was largest when the tone preceding the onset of the ramp was constant and decreased in amplitude when the slope of the preceding tone deviated from zero either in the positive or negative direction with the positive slope having the more marked attenuating effect. The standard deviation (S.D.) of the distributions of reaction times to stimulus onset correlated negatively with the average AEP amplitude. The attenuation of the averaged AEP appeared to be related to the uncertainty of the subjects as to when the various types of stimuli occurred. The above findings on AM ramp stimuli closely parrellel our previously reported findings on frequency modulated ramp stimuli

Frequency modulated (FM) auditory stimuli result in average vertex potentials similar to the usual auditory average evoked potential (AEP). For stepwise increase or decrease in tone frequency the AEPs are similar. For FM stimuli modulated by pulses of different durations 'on' responses are evoked by the transition of the stimulus from the longer duration to the shorter duration frequency tone while 'off' responses result when the frequency transition is from the shorter to the longer duration tone. Ramp modulation of the stimulus frequency results in average evoked responses; the amplitude of these responses is proportional to the slope of the ramp as well as the frequency of the tone that precedes the ramp. Thus, if the tone preceding the ramp is also a ramp but of smaller slope the AEP is attenuated and with sufficiently large slope the AEP can be completely extinguished. No AEPs were obtained at the offset of ramp modulated stimuli. The standard deviation (S.D.) of the reaction time (RT) distributions to stimulus onset indicate that the AEP amplitude is inversely proportional to the S.D. values. Thus, the attenuation phenomena appeared to be related to the uncertainty of the subject as to the exact time the stimulus occurred, both of which seem to be the result of sensory difficulty to the type of stimuli used. AEPs to negative ramps were smaller than AEPs to positive ramps; this may be on account of the psychological inequality between the stimuli