RESUMO
BACKGROUND: Medical residents' training in ultrasonography usually follows the recommendations of the American College of Emergency Physicians (ACEP), even though these do not provide specific technical guidelines. Adequate training is considered to require 25 practical iterations in the majority of ultrasound procedures. However, the effectiveness of this approach has not been verified experimentally. We set out to determine the number of repetitions required for an acceptable ultrasound procedure of the inferior vena cava (IVC), as an important and emerging ultrasound procedure in cardiology. METHODS: Using three human models, each of eight medical residents in the Emergency Medicine (EM) Program at the Universidad del Rosario performed 25 iterations of the recommended procedure, with image quality evaluation by an EM physician expert in the technique. Logistic regression analysis was used to determine the lowest number of repetitions required to achieve an adjusted probability of success of 80 and 90 %, respectively. RESULTS: We obtained 200 ultrasound images. The percentage success by each resident ranged from 52 to 96 %. There was no statistical significance in the relation between gender and success (p = 0.83), but there was an association between year of residency and success (p < 0.001). The average time taken for each procedure was 17.3 s (SD 8.1); there was no association between the time taken and either repetition number or image quality. We demonstrate that eleven repetitions are required to achieve acceptable image quality in 80 %, and that 21 repetitions are required to achieve acceptable image quality in 90 %. CONCLUSIONS: This is the first study to formally evaluate the effectiveness of recommended training in ultrasound techniques. Our findings demonstrate that training comprising 25 procedural repetitions is easily sufficient to achieve optimal image quality, and they also provide empiric knowledge toward elucidating the times and minimum repetitions needed to acquire and improve ultrasonographic technique in novice operators to a level which fulfills quality requirements for interpretation.
RESUMO
AIM: To analyze changes in prevalence and seasonality of diarrhea morbidity and mortality and to evaluate the impact of rotavirus disease among Mexican children younger than 5 years old. METHODS: Diarrhea surveillance was performed from 1990 to 2002. Rotavirus testing was performed on stool specimens from 1996 to 2002. Data were obtained from different surveillance systems considering a nationwide representation in Mexico. Diarrhea morbidity and mortality rates were analyzed against time to determine trends or seasonal patterns. RESULTS: Improvement of surveillance for all diarrhea episodes denoted an initial morbidity increase from 1995 to 1999, followed by a decrease by 2002, without any seasonal pattern. However, from 1990 to 1995, morbidity for severe diarrhea decreased 63%. From 1996 to 2002, 62-68% of severe diarrhea episodes occurring during the fall-winter season (FWS) were rotavirus-positive compared with 6-12% in the spring-summer season (SSS). From 1990 to 2002, diarrhea mortality decreased 84%. Higher mortality rates for children younger than 1 year old coincided precisely during the FWS, annually. Both severe diarrhea episodes and diarrhea deaths denoted a changing seasonal pattern. In 1990-1991, 2 waves of increased diarrhea activity occurred. The increase in SSS was much more pronounced than that in FWS. From 1992 to 1995 for severe diarrhea and from 1993 to 2002 for diarrhea deaths, the SSS frequencies subsequently reduced, whereas the FWS peaks remained annually. CONCLUSIONS: A significant reduction in morbidity and mortality of severe diarrhea has occurred from 1990 and 2002 in Mexican children younger than 5 years old. This is a consequence of preventive programs initiated for cholera control since 1991, which had greater impact on SSS diarrhea and limited response for FWS diarrhea, when rotavirus is mainly present. Currently rotavirus diarrhea requires new prevention strategies and specific control measures, such as a specific national vaccine program.