Estimating the best fraction of inspired oxygen for calculation of PaO2/FiO2 ratio in acute respiratory distress syndrome due to COVID-19 pneumonia.

Background: The ratio of partial pressure of oxygen in arterial blood (PaO2) to the fraction of inspiratory oxygen concentration (FiO2) is an indicator of pulmonary shunt fraction. PaO2/FiO2 (P/F) ratio is used to classify severity of acute respiratory distress syndrome (ARDS). With the same shunt fraction, P/F ratio decreases with increases in FiO2 which may lead to errors in classifying severity of ARDS. The effect of FiO2 on P/F ratio has not been investigated in COVID-19 pneumonia. In this study, we estimated the best FiO2 for the calculation of P/F ratio in a sample of patients with ARDS due to COVID-19 pneumonia. Materials and Methods: Blood gas and ventilatory data of 108 COVID-19 ARDS patients were analyzed in a cross-sectional observational study. Using Oxygen Status Algorithm the calculated shunt fraction served a basis for calculating P/F ratio for different FiO2. The severity of ARDS determined by P/F ratios at each FiO2s was compared with the shunt-based severity to find the optimum FiO2 for calculation of P/F ratio so the resulting classification has the best match with the reference classification. Results: A FiO2 of 1.0 for calculation of P/F ratio and ARDS classification showed the best match with shunt-based ARDS classification. A regression model was obtained with the PaO2, patient's original FiO2, Hemoglobin concentration, and SaO2 as the independent predictors of the P/F ratio for the FiO2 of 1.0. Conclusion: This study shows a FiO2 of 1.0 as the best value for correct calculation of P/F ratio and proper classification of ARDS.

Comparing Sedative Effect of Dexmedetomidine versus Midazolam for Sedation of Children While Undergoing Computerized Tomography Imaging.

BACKGROUND: Pediatric anxiety and restlessness may create issues and difficulties in performing accurate diagnostic studies even noninvasive ones, such as radiological imaging. There are some agents that will help to get this goal. This study aimed to compare the intranasal effect of dexmedetomidine (DEX) and midazolam (MID) for sedation parameters of children undergoing computerized tomography (CT) imaging. MATERIALS AND METHODS: A double-blind clinical trial was conducted on 162 eligible children who underwent CT imaging. These patients were divided into two groups including MID (n = 81) with dose of 0.3 mg.kg and DEX (n = 81) with dose of 3 µg.kg, which was consumed intranasally. The mean blood pressure (MBP), respiratory rate (RR), heart rate (HR), and oxygen saturation (O2Sat) in children were recorded. Then, time of initiation, level of sedation, and duration effect of medication were measured at 0, 10, 20, and 30 min. Parents and clinician satisfaction score was asked. All data were analyzed using the Statistical Package for the Social Sciences (SPSS) software by t test and chi-square test. RESULTS: Decreasing in MBP and HR was higher in DEX group than MID group (P < 0.001), whereas decrease of O2Sat in MID group was higher than DEX group (0.009). Starting time of sedation (22.72 ± 11.64 vs. 33.38 ± 10.17, P = 0.001) was lower in DEX group. Parents (P < 0.001) and physician (P < 0.001) satisfaction score was higher in DEX group than the MID group. CONCLUSION: Using 3 µg/kg intranasal DEX for sedation of 1-6-year-old children was a suitable method to undergo noninvasive studies such as CT imaging. Intranasal DEX is superior to MID due to higher sedation satisfactory, faster starting effect of sedation, and lower side effects and complications. Nevertheless, in children with hemodynamic instability DEX is not an appropriate choice.

Metabolic and endocrinologic complications in beta-thalassemia major: a multicenter study in Tehran.

ABSTRACT : BACKGROUND : The combination of transfusion and chelation therapy has dramatically extended the life expectancy of thalassemic patients. The main objective of this study is to determine the prevalence of prominent thalassemia complications. METHODS : Two hundred twenty patients entered the study. Physicians collected demographic and anthropometric data and the history of therapies as well as menstrual histories. Patients have been examined to determine their pubertal status. Serum levels of 25(OH) D, calcium, phosphate, iPTH were measured. Thyroid function was assessed by T3, T4 and TSH. Zinc and copper in serum were determined by flame atomic absorption spectrophotometry. Bone mineral density (BMD) measurements at lumbar and femoral regions have been done using dual x-ray absorptiometry. The dietary calcium, zinc and copper intakes were estimated by food-frequency questionnaires. RESULTS : Short stature was seen in 39.3% of our patients. Hypogonadism was seen in 22.9% of boys and 12.2% of girls. Hypoparathyroidism and primary hypothyroidism was present in 7.6% and 7.7% of the patients. About 13 % of patients had more than one endocrine complication with mean serum ferritin of 1678 +/- 955 micrograms/lit. Prevalence of lumbar osteoporosis and osteopenia were 50.7% and 39.4%. Femoral osteoporosis and osteopenia were present in 10.8% and 36.9% of the patients. Lumbar BMD abnormalities were associated with duration of chelation therapy. Low serum zinc and copper was observed in 79.6% and 68% of the study population respectively. Serum zinc showed significant association with lumbar but not femoral BMD. In 37.2% of patients serum levels of 25(OH) D below 23 nmol/l were detected. CONCLUSION : High prevalence of complications among our thalassemics signifies the importance of more detailed studies along with therapeutic interventions.