Respiratory Failure in a Child Due to Type 2 Postobstructive Pulmonary Edema.

BACKGROUND: Postobstructive pulmonary edema (POPE), sudden pulmonary edema after upper airway obstruction, is an important disease entity for pediatric emergency physicians to recognize and initiate prompt treatment. Type 1 POPE occurs after a sudden, severe upper airway obstruction, whereas type 2 POPE develops after acute relief of chronic airway obstructive. CASE: A 12-year-old boy, with a history of untreated sleep apnea, on postoperative day 2 from appendectomy, was brought to the emergency department in respiratory distress. The patient required urgent intubation, and copious pink frothy fluid was suctioned from the endotracheal tube. He was initially difficult to oxygenate, but with ventilator setting changes including a high positive end-expiratory pressure, the patient improved. He was discharged on hospital day 3 with nighttime BiPAP for home use. CONCLUSIONS: Type 2 POPE should be considered in a patient presenting with respiratory distress and a history of sleep apnea. Optimal ventilator management includes use of PEEP in the 10 to 15 cm H2O range. The roles of diuretics and steroids are controversial. Most patients will do well after a brief period of ventilatory support (24-48 hours). With the rise of ambulatory surgery, pediatric emergency physicians must be attuned to both the surgical and anesthetic complications that occur in the early postoperative period.

Measuring arterial oxygenation in a high altitude field environment: comparing portable pulse oximetry with blood gas analysis.

OBJECTIVE: High altitude environments present unique medical treatment challenges. Medical providers often use small portable pulse oximetry devices to help guide their clinical decision making. A significant body of high altitude research is based on the use of these devices to monitor hypoxia, yet there is a paucity of evidence that these devices are accurate in these environments. We studied whether these devices perform accurately and reliably under true mountain conditions. METHODS: Healthy unacclimatized active-duty military volunteers participating in mountain warfare training at 2100 m (6900 feet) above sea level were evaluated with several different pulse oximetry devices while in a cold weather, high altitude field environment and then had arterial blood gases (ABG) drawn using an i-STAT for comparison. The pulse oximeter readings were compared with the gold standard ABG readings. RESULTS: A total of 49 individuals completed the study. There was no statistically significant difference between any of the devices and the gold standard of ABG. The best performing device was the PalmSAT (PS) 8000SM finger probe with a mean difference of 2.17% and SD of 2.56 (95% CI, 1.42% to 2.92%). In decreasing order of performance were the PS 8000AA finger probe (mean ± SD, 2.54% ± 2.68%; 95% CI, 1.76% to 3.32%), the PS 8000Q ear probe (2.47% ± 4.36%; 95% CI, 1.21% to 3.75%), the Nonin Onyx 9500 (3.29% ± 3.12%; 95% CI, 2.39% to 4.20%), and finally the PS 8000R forehead reflectance sensor (5.15% ± 2.97%; 95% CI, 4.28% to 6.01%). CONCLUSIONS: Based on the results of this study, results of the newer portable pulse oximeters appear to be closely correlated to that of the ABG measurements when tested in true mountain conditions.

Effect of deferasirox on iron absorption in a randomized, placebo-controlled, crossover study in a human model of acute supratherapeutic iron ingestion.

STUDY OBJECTIVE: In 2005, the Food and Drug Administration approved deferasirox as an oral iron chelating agent for chronic iron overload. To determine usefulness in management of acute iron ingestion, we study the effect of orally administered deferasirox in healthy human adults. METHODS: A double-blinded, placebo-controlled, randomized, crossover study of 8 healthy human volunteers was conducted. Subjects ingested 5 mg/kg of elemental iron in the form of ferrous sulfate. One hour after iron ingestion, subjects were randomized to receive 20 mg/kg of deferasirox or placebo. Serial iron levels were then obtained. A 2-week washout was used between study arms. The paired t test was used to compare area under time-concentration curves from baseline to both 12- and 24-hour iron levels between groups. RESULTS: Baseline serum iron levels were similar in the 2 groups. Deferasirox significantly reduced serum iron area under concentration-time curves compared with placebo during both 1 to 12 hours and 1 to 24 hours (12 hour=577 µmol-hour/L and 392 µmol-hour/L, 95% confidence interval for the difference 15.8 to 353.0 µmol-hour/L; 24 hour=808 µmol-hour/L and 598 µmol-hour/L, 95% confidence interval for difference 54.4 to 366.7 µmol-hour/L). CONCLUSION: Orally administered deferasirox significantly reduced serum iron levels when administered 1 hour after iron ingestion during the 12- and 24-hour periods after acute ingestion of 5 mg/kg of elemental iron in healthy human volunteers. Further study is required to determine optimal dosing, but deferasirox may be an important addition to current therapy for acute iron poisoning.

Comparison of oral aspirin versus topical applied methyl salicylate for platelet inhibition.

BACKGROUND: Oral acetylsalicylic acid (aspirin) is the primary antiplatelet therapy in the treatment of acute myocardial infarction and acute coronary syndrome. Methyl salicylate (MS; oil of wintergreen) is compounded into many over-the-counter antiinflammatory muscle preparations and has been shown to inhibit platelet aggregation locally and to be absorbed systemically. OBJECTIVE: To assess the ability of topically applied MS to inhibit systemic platelet aggregation for patients who are unable to tolerate oral drug therapy. METHODS: A randomized, prospective, blinded, crossover study was conducted in 9 healthy men, aged 30-46 years. All subjects ingested 162 mg of aspirin or applied 5 g of 30% MS preparation to their anterior thighs. There was a minimum 2-week washout period between study arms. Blood and urine were collected at baseline and at 6 hours. An aggregometer measured platelet aggregation over time against 5 standard concentrations of epinephrine, and a mean area under the curve (AUC) was calculated. Urinary metabolites of thromboxane B(2) were measured by a standard enzyme immunoassay. Differences in and between groups at baseline and 6 hours were tested by the Wilcoxon signed-rank test. RESULTS: Baseline platelet aggregation did not differ significantly between the 2 arms of the study (median AUC [% aggregation(*)min]; binominal confidence intervals): aspirin 183; 139 to 292 versus MS 197; 118 to 445 (p = 0.51). Both aspirin and MS produced statistically significant platelet inhibition; aspirin decreased the AUC from 183; 139 to 292 to 85; 48 to 128 (p = 0.008) and MS decreased the AUC from 197; 118 to 445 to 112; 88 to 306 (p = 0.011). No significant difference was detected between baseline and 6-hour thromboxane levels for either aspirin (p = 0.779) or MS (p = 0.327). CONCLUSIONS: Topical MS and oral aspirin both significantly decrease platelet aggregation in healthy human volunteers.

Effect of oral calcium disodium EDTA on iron absorption in a human model of iron overdose.

OBJECTIVE: Anecdotal case reports and animal models have suggested that the administration of CaNa2EDTA (EDTA) may be effective in reducing the absorption of iron after an oral iron overdose. We designed this study to determine the effect of orally administrated EDTA with or without activated charcoal (AC) on iron absorption after a mild iron ingestion in healthy human volunteers. METHODS: A randomized, crossover study was conducted in eight healthy human volunteers. All subjects ingested 5 mg/kg of elemental iron in the form of ferrous sulfate. One hour post ingestion, subjects were randomized to receive 35 mg/kg EDTA, EDTA plus 50 grams of AC, or water. Serial iron levels were obtained at baseline and every hour for the first 6 hours, then at 8, 12, and 24 hours. A 2-week washout was used between study arms. The Kruskal-Wallis test was used for the following comparisons between treatment groups: baseline serum iron levels, area under time-concentration curves (AUCs) from baseline to 12 hours and baseline to 24 hours, and peak iron levels. RESULTS: Baseline serum iron levels did not differ among the three treatment groups (p = 0.844). AUCs were not different among groups (p = 0.746 for 12 hr, p = 0.925 for 24 hr). AUC medians (with 95% binomial confidence bounds) for control, EDTA, EDTA + AC groups, respectively, for 12 hr were: 2813 (2298, 3561), 2570 (1669, 3476), and 2654 (2125, 3600); and for 24 hr were: 4083 (3488,5314), 4139 (2666, 5547), and 4274 (3336, 5577). Peak serum iron levels did not differ among treatment groups (p = 0.481). Peak iron level medians in microg/dL (with 95% binomial confidence bounds) were for control: 329 (253, 382), for EDTA: 271 (184, 375), and for EDTA + AC: 285 (229, 352). CONCLUSION: Orally administered EDTA did not significantly reduce iron absorption when administered 1 hour post iron ingestion during the 12 or 24-hour period following the ingestion of 5 mg/kg of elemental iron in healthy human volunteers.