Comparison of Commercial Versus Homemade Models for Teaching Ultrasound-Guided Peripheral I.V. Placement.

BACKGROUND: Various commercially available and do-it-yourself (DIY) models are used to teach emergency medicine (EM) residents and medical students ultrasound (US)-guided i.v. insertion. Expensive commercial models degrade over time, but DIY models are inexpensive, easily prepared, and readily discarded. OBJECTIVE: We tested the hypothesis that DIY models are equally effective as commercial models for teaching US-guided i.v. insertion, and using a controlled trial to subjectively evaluate how well DIY models and commercially manufactured models compare with human tissue both tactilely and sonographically. METHODS: We tested three models for US-guided i.v. teaching-a commercially available model US training block model, a homemade tofu model, and a homemade gelatin model. All three models were compared with US-guided i.v. insertion involving human tissue. Study participants were EM residents and EM attendings experienced in US-guided i.v. placement in real patients. After practicing peripheral i.v. placement under US guidance using the three media, participants at various levels of training and experience with US-guided i.v. insertion subjectively described how each media compared tactilely and sonographically, which model was most similar to a live human overall, and which model was best for instructing learners. RESULTS: The overall score (sum of visual and sonographic scores) for the gelatin model was significantly higher than either of the other models, indicating that the gelatin model was evaluated as most approximate to the anatomy of a human compared with the other models. CONCLUSIONS: Inexpensive homemade alternatives to commercial simulators can be realistic and effective surrogates for learning US-guided peripheral i.v.

Overweight/obesity and gastric fluid characteristics in pediatric day surgery: implications for fasting guidelines and pulmonary aspiration risk.

BACKGROUND: The safety of 2-h preoperative clear liquid fasts has not been established for overweight/obese pediatric day surgical patients. Healthy children and obese adults who fasted 2 h have small residual gastric fluid volumes (GFVs), which are thought to reflect low pulmonary aspiration risk. We sought to measure the prevalence of overweight/obesity in our day surgery population. We hypothesized that neither body mass index (BMI) percentile nor fasting duration would significantly affect GFV or gastric fluid pH. In children who were allowed clear liquids up until 2 h before surgery, we hypothesized that overweight/obese subjects would not have increased GFV over lean/normal subjects and that emesis/pulmonary aspiration events would be rare. METHODS: Demographics, medical history, height, and weight were recorded for 1000 consecutive day surgery patients aged 2-12 yr. In addition, 1000 day surgery patients (age 2-12 yr) undergoing general endotracheal anesthesia were enrolled. After tracheal intubation, a 14-18F orogastric tube was inserted and gastric contents evacuated. Medications, fasting interval, GFV, pH, and emetic episodes were documented. Age- and gender-specific Center for Disease Control and Prevention growth charts (2000) were used to determine ideal body weight (IBW = 50th percentile) and to classify patients as lean/normal (BMI 25th-75th percentile), overweight (BMI > or = 85th to <95th percentile), or obese (BMI > or = 95th percentile). RESULTS: Of all day surgery patients, 14.0% were overweight and 13.3% were obese. Obese children had lower GFV per total body weight (P < 0.001). When corrected for IBW, however, volumes GFV(IBW) were identical across all BMI categories (mean 0.96 mL/kg, sd 0.71; median 0.86 mL/kg, IQR 0.96). Preoperative acetaminophen and midazolam contributed to increased GFV(IBW) (P = 0.025 and P = 0.001). Lower GFV(IBW) was associated with ASA physical status III (P = 0.024), male gender (P = 0.012), gastroesophageal reflux disease (P = 0.049), and proton pump inhibitor administration (P = 0.018). GFV(IBW) did not correlate with fasting duration or age. Decreased gastric fluid acidity was associated with younger age (P = 0.005), increased BMI percentile (P = 0.036), and African American race (P = 0.033). Emesis on induction occurred in eight patients (50% of whom were obese, P = 0.052, and 75% of whom had obstructive sleep apnea, P = 0.061). Emesis was associated with increased ASA physical status (P = 0.006) but not with fasting duration. There were no pulmonary aspiration events. CONCLUSIONS: Twenty-seven percent of pediatric day surgery patients are overweight/obese. These children may be allowed clear liquids 2 h before surgery as GFV(IBW) averages 1 mL/kg regardless of BMI and fasting interval. Rare emetic episodes were not associated with shortened fasting intervals in this population.