Emergency medicine resident interpretation of pediatric radiographs

OBJECTIVE

To examine the concordance of pediatric radiograph interpretation between emergency medicine residents (EMRs) and radiologists.

METHODS

A prospective, observational study was performed in a university pediatric ED with an annual census of 60,000 visits. Radiographs ordered by EMRs from December 1993 through October 1994 were initially interpreted solely by the EMR, with subsequent unmasked final review by attending radiology staff. Misinterpreted radiographs were placed into 3 categories. The groupings included overreads, underreads with no change in treatment, and underreads that required a change in treatment.

RESULTS

A total of 415 radiographs were interpreted by PGY1-3 residents. Overall concordance was found for 371 radiographs (89.4%). There were 44 misinterpretations (10.6%), with 24 (5.78%) overreads, 13 (3.13%) underreads, and 7 (1.69%) underreads that required follow-up interventions. Misinterpretations were similar for the different levels of training: [table: see text] The 5 most frequently ordered radiographs were chest (28%), ankle (7%), foot (6%), wrist (5%), and hand (5%). The most frequently misinterpreted radiographs were sinus, foot, shoulder, facial, and hand.

CONCLUSION

89.4% of all the radiographs interpreted by PGY1-3 residents were read correctly. Only 1.69% of the misinterpreted radiographs led to a change in management. Level of training did not significantly correlate with radiograph misinterpretation rates.

Radiographic interpretation in the emergency department

This study examined the concordance of radiographic readings between emergency department (ED) attending physicians and radiologists in a community teaching hospital. In addition, the incidents of misinterpretations leading to an alteration in patient care were also reviewed. All radiographs obtained from January through October 1993 were initially interpreted by ED attending physicians with subsequent final review by attending radiology staff. Misread radiographs were placed into one of three categories. The groupings included overread radiographs with no change in treatment, underread radiographs with no change in treatment, and radiograph misinterpretations with a change in treatment. Of 15,585 radiographs obtained during the study period, there were 120 misreads; 12,099 (77.6%) of the 15,585 radiographs had an initial emergency physician interpretation. Radiographic misinterpretations included 7 (5.78%) overreads, 57 (47.1%) underreads, and 57 (47.51%) misreads requiring follow-up (MR-FU). The five most frequently misread radiographs were: abdominal, 12/247 (4.4%); rib, 3/99 (3.0%); foot, 13/621 (2.1%); hip, 3/152 (1.9%); and ankle 11/758 (1.4%). The most frequently obtained radiographs included: chest, 7,012 (0.33% MR-FU); cervical spine, 1,112 (0.18% MR-FU); ankle, 758 (0.66% MR-FU); knee, 633 (0.32% MR-FU); and foot, 621 (0.97% MR-FU). In this study, 99.0% of all emergency department radiographs were read correctly on initial review by ED attending physicians. Of all misread radiographs, less than half (46%) were deemed clinically significant and required a follow-up intervention.

The esophageal detector device: accuracy and reliability in difficult airway settings

INTRODUCTION

The esophageal detector device (EDD) recently has been found to assess endotracheal (ET) tube placement accurately. This study describes the reliability of the EDD in determining the position of the ET tube in clinical airway situations that are difficult.

METHODS

This was a prospective, randomized, single-blinded, controlled laboratory investigation. Two airway managers (an emergency-medicine attending physician and a resident) determined ET-tube placement using the EDD in five swine in respiratory arrest. The ET tube was place in the following clinical airway situations: 1) esophagus; 2) esophagus with 1 liter of air instilled; 3) trachea; 4) trachea with 5 ml/kg water instilled; and 5) right mainstem bronchus. Anatomic location of the tube was verified by thoracotomy of the left side of the chest.

RESULTS

There was 100% correlation between the resident and attending physician's use of the EDD. The EDD was 100% accurate in the determining tube placement in the esophagus, in the esophagus with 1 liter of air instilled, in the trachea, and in the right mainstem bronchus. The airway managers were only 80% accurate in detecting tracheal intubations when fluid was present.

CONCLUSIONS

The EDD is an accurate and reliable device for detecting ET-tube placement in most clinical situations. Tube placement in fluid-filled trachea, lungs, or both, which occurs in pulmonary edema and drowning, may not be detected using this device.

Right lung ventilation in a porcine open-chest shock model

OBJECTIVE

To determine the effect of selective right lung ventilation on gas exchange and hemodynamics when compared with bilateral lung ventilation in a porcine open-chest shock model.

METHODS

A randomized, controlled laboratory investigation was performed using a static hemorrhagic shock model in 12 adult swine undergoing thoracotomy. The animals were subjected to a fixed 40% circulating blood volume hemorrhage over 20 minutes. Each animal was then assigned to either a tracheal (control) or a right mainstem (experimental) intubation group. Minute ventilation was held constant in both groups and tidal volumes were decreased by 33% in the right mainstem intubation group. Following intubation and left lateral thoracotomy, another 20% fixed-volume hemorrhage was instituted simultaneously with IV crystalloid and whole blood resuscitation for both groups over 30 minutes. Heart rate, blood pressure, and arterial blood gases were measured at 5-minute intervals.

RESULTS

There was no significant difference between the control and experimental groups for any of the measured variables, including mean arterial pressure, pH, partial arterial pressure of CO2 (PaCO2), and PaO2, over time. All animals survived the study protocol.

CONCLUSION

Selective right lung ventilation has no detrimental effect on gas exchange or hemodynamics when compared with standard bilateral lung ventilation in a porcine open-chest shock model.

Effect of nitrous oxide analgesia on pneumothorax

OBJECTIVE

To address whether spontaneous inhalation of 50% nitrous oxide (N2O) for up to 30 minutes adversely affects swine with pneumothorax (PNTX).

METHODS

Five fasted, female swine (13-17 kg) were sedated with IV ketamine, intubated, and allowed to spontaneously inhale either 50% N2O or room air (RA) in a sequential crossover design in which each animal served as its own RA control. Small (group 1, 150 mL), medium (group II, 300 mL), and large (group III, 500 mL) PNTXs were created by instilling air into the left pleural space via an 18-Fr three-way Foley catheter. Changes in PNTX volume, heart rate (HR), central venous pressure (CVP), blood pressure (BP), ECG. and arterial blood gas (ABG) parameters were recorded in separate 10- and 30-minute trials. A 15-minute washout period was given between each trial. Data were analyzed using repeated-measures analysis of variance with post-hoc Tukey's tests.

RESULTS

No significant increase in PNTX size was seen during the 10-minute trials. In the 30-minute trials, a statistically significant increase in absolute PNTX size was seen with N2O compared with RA for group I (44 +/- 17 vs 16 +/- 5 mL, p = 0.02), group II (61 +/- 21 vs 26 +/- 4 mL, p = 0.01), and group III (62 +/- 32 vs 40 +/- 5 mL, p = 0.06). No difference in HR, CVP, MAP, ABGs, or ECG were observed between the N2O and RA trials for any size PNTX. No animal developed hemodynamic signs of tension pneumothorax.

CONCLUSION

In this model, spontaneous inhalation of 50% N2O for up to 30 minutes is associated with little risk of hemodynamic or respiratory compromise. Although PNTX size increases with 50% N2O use, the magnitude observed in this animal model is less than previously reported.

Pediatric pain control and conscious sedation: a survey of emergency medicine residencies

OBJECTIVE

To determine the availability and relative use of pediatric analgesia and sedation at sites of U.S. emergency medicine residency training programs.

METHODS

A mail/telephone survey of residency directors at 80 U.S. emergency medicine residencies regarding resident experience with pediatric analgesia and sedation for painful procedures conducted during November 1991.

RESULTS

Sixty of 80 surveys (75%) were completed and available for analysis. Emergency medicine faculty supervised conscious sedation and analgesia in 87% of responding programs, while pediatrics faculty and pediatrics-emergency medicine fellows supervised in the remainder. Ninety-three percent of the programs had sedating agents available in the emergency department; only four programs needed to have drugs brought from the pharmacy. Thirty-four programs (57%) had formal protocols for the administration of these drugs. Seventy-seven percent of the programs had airway resuscitation equipment at the bedside, while only 63% brought resuscitation drugs. However, 60% of the programs reported complications of sedation, including respiratory depression, prolonged sedation, agitation, and vomiting. The most commonly used agents were midazolam (82%), meperidine alone (68%) and with promethazine and chlorpromazine (67%), and chloral hydrate (67%). Only 25% of the programs used nitrous oxide, and 30% used ketamine.

CONCLUSIONS

Emergency medicine residencies generally have available agents for pain control and conscious sedation in children, although the agents used vary widely. Appropriate instruction by trained faculty should enhance resident experience with pediatric pain control and sedation.

Activated charcoal surface area and its role in multiple-dose charcoal therapy

The study hypothesis was to prove that increasing the surface area (SA) of activated charcoal (AC) will enhance theophylline elimination in multiple-dose AC therapy. Five healthy, nonsmoking, nonmedicated, volunteer men ranging from the ages of 18 to 24 years old were entered onto the study. A prospective, randomized, crossover study was conducted with each subject serving as their own control. Subjects fasted overnight before receiving 8 mg/kg of intravenous theophylline at the beginning of a control phase and two study phases. No AC was administered in the control phase. Two experimental phases compared Actidose Aqua AC (1,500 m2/g; Paddock Laboratories, Inc, Minneapolis, MN) with Norit A Supra AC (2,000 m2/g; Norit NV, Amersfoort, the Netherlands). In each phase, 50 g of the AC was administered orally after the conclusion of the theophylline infusion. Subsequent 50-g doses of the AC preparation were administered at 4 and 8 hours after the initial dose of AC. Serial blood samples for theophylline level determinations were obtained at 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0, and 12.0 hours after the completion of the theophylline infusion. For each of the three data sets, the absolute area under the absorption curve (A-AUC) was calculated to infinity using the trapezoidal rule. Additionally, the relative area under the absorption curve (R-AUC) was determined for each data set. Data were analyzed using repeated measures of analysis of variance (ANOVA) and Tukey's test. The alpha error was set at 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapeutic and diagnostic efficacy of adenosine in wide-complex tachycardia

Wide-complex tachycardia is one of the most challenging problems faced by emergency physicians. Adenosine is an endogenous nucleoside that has gained recent popularity as an anti-arrhythmic drug in the setting of supraventricular tachycardia. We present the cases of two patients with stable wide-complex tachycardia in which adenosine was administered for therapeutic and diagnostic effects. Both patients quickly converted into sinus rhythm with subsequent diagnoses of atrioventricular reciprocating tachycardia secondary to Wolff-Parkinson-White syndrome. The role of adenosine in the acute management of wide-complex tachycardia is discussed.

The comparative efficacy of various multiple-dose activated charcoal regimens

Multiple-dose activated charcoal therapy is used in the management of poisoning emergencies to enhance the elimination of enterohepatically and enteroenterically secreted toxins. This study was conducted to determine if increasing the frequency of activated charcoal administration would enhance the elimination of a toxin. In this crossover study, five healthy adult volunteers were randomly assigned to either a control phase or one of three study phases. Subjects in the control phase and each of the study phases received an intravenous infusion of aminophylline (8 mg/kg). During the study phases each subject additionally received activated charcoal 50 gm and activated charcoal 12.5 gm every hour, 25 gm every 2 hours, or 50 gm every 4 hours over a 8-hour period for a cumulative activated charcoal dose of 150 gm. Ten blood samples were obtained over 12 hours and analyzed for theophylline concentrations. Using area under the curve and half-life calculations it was determined that each of the dosage regimens significantly reduced the reabsorption of theophylline and the plasma half-life when compared with control. There were no significant differences between any of the treatment groups. Decreasing the dose but increasing the frequency of activated charcoal administration is as effective as the traditional every 4 hour-therapy regimen.

Dextromethorphan poisoning reversed by naloxone

Dextromethorphan, a common ingredient in cough syrups, has rarely been described to cause toxicity. The authors describe an unusual case of a known asthmatic presenting with somnolence, who appeared to be in end-stage respiratory failure. Her partial response to routine naloxone, 1 mg, was surprising. However, additional naloxone was required to completely normalize the patient's mental status. The authors suggest naloxone be administered in doses of 0.4 mg or more intravenously in suspected dextromethorphan overdose.

Manual translaryngeal jet ventilation and the risk of aspiration in a canine model

STUDY OBJECTIVES

Manual translaryngeal jet ventilation (TLJV) is a safe and effective method of maintaining normal ventilation in apneic subjects. Little data exist on the amount of airway protection afforded with this technique of airway management. We sought to evaluate the risk of aspiration during manual TLJV.

SETTING

Data were collected in a laboratory animal model.

DESIGN

A prospective, nonrandomized, controlled trial was performed.

PARTICIPANTS

Seventeen adult apneic mongrel dogs were enrolled.

INTERVENTIONS

Intratracheal Gastrograffin was instilled and radiographic changes assessed during ventilation using a 0 to 3 scale (none to severe). Thirty-six trials were performed, with equal numbers at both 30 degrees and 45 degrees head elevation. The three groups studied were animals without airway protection (control), animals with a cuffed endotracheal tube (tube), and animals with a percutaneous TLJV cannula and a 50-psi oxygen source ventilated at a rate of 20 breaths per minute (jet).

MEASUREMENTS AND MAIN RESULTS

Significantly less radiographic evidence of aspiration was noted in the jet and tube groups at 30 degrees and 45 degrees compared with control animals (P = .002 each). At 45 degrees head elevation a trend toward increased aspiration scores in the jet group compared with the tube group (P = .065) was observed.

CONCLUSION

In our model, manual TLJV at 20 breaths per minute and an I:E ratio of 1:2 provided protection from aspiration comparable to that observed with a cuffed endotracheal tube at 30 degrees head elevation. At 45 degrees elevation, this protection was diminished.

Correct positioning of an endotracheal tube using a flexible lighted stylet

Endotracheal intubation is not without complications, among the most serious of these being misplacement of the endotracheal (ET) tube. Unrecognized esophageal placement is a lethal complication, but even when placed in the trachea, ET tubes can be displaced distally and enter a mainstem bronchus. Correct positioning of an ET tube is usually defined as the placement of the tube within the trachea approximately 5 cm above the carina. Chest x-ray is the most common and a reliable method of demonstrating correct positioning, particularly in ICU patients. Using transillumination by means of a flexible stylet (lightwand), we investigated whether transillumination could position an ET tube consistently within 5 +/- 2 cm of the carina. Ten human cadavers of varied weight and body habitus were intubated under direct vision and 10 ml of a radiopaque dye was injected down the tube as a marker for the carina. A premeasured flexible lighted stylet was then inserted into the inplace tube so that the bulb was positioned at the tube's distal opening. The brightest transilluminated glow produced by the bulb was then positioned at the sternal notch. A chest x-ray was taken and the distance of the tube tip from the carina was calculated. In each case the tube tip could be placed consistently at a level 5 +/- 1 cm from the carina by observing the maximal transilluminated glow at the sternal notch. We conclude that transillumination of the neck using a flexible lighted stylet can accurately and consistently position an ET tube at an appropriate distance above the carina.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective anterior cruciate ligament testing

We examined subjects with the Stryker knee laxity tester as part of the clinical examination to determine its usefulness in evaluating the anterior cruciate ligament. We measured 123 athletes with no history of knee injury, as well as 30 patients with ACL injury proven by arthroscopy, and 11 injured patients with intact ACL at arthroscopy. We recorded anterior and posterior tibial displacement at 20 degrees of knee flexion and 20 lbs force in each direction. Anterior laxity and side to side difference correlated with ACL injury; posterior and total AP laxity did not. In normal subjects, mean anterior laxity was 2.5 mm. Only 8% of normal knees had anterior laxity of 5 mm or more. Ten percent of normal subjects had a side to side difference of 2 mm or more. In ACL tears, mean laxity was 8.1 mm, with 94% measuring 5 mm or more. Of the subjects, 89% with unilateral ACL injury had an increase of 2 mm or more on the injured side. Ten of ten acute ACL tears were detected by these criteria, with no false positives. In injured knees with intact ACL, measurements did not differ significantly from normal. We found the objective knee laxity measurement to be a useful complement to clinical knee examination.