Simultaneous determination of the accuracy and precision of closed-circuit cardiac output rebreathing techniques

2007 ◽  
Vol 103 (3) ◽  
pp. 867-874 ◽  
Author(s):  
S. S. Jarvis ◽  
B. D. Levine ◽  
G. K. Prisk ◽  
B. E. Shykoff ◽  
A. R. Elliott ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Simultaneous Determination ◽  
Maximal Exercise ◽  
Single Step ◽  
Accuracy And Precision ◽  
Bartlett’S Test ◽  
Rebreathing Method ◽  
Rebreathing Methods ◽  
Rest And Exercise

Foreign and soluble gas rebreathing methods are attractive for determining cardiac output (Q̇c) because they incur less risk than traditional invasive methods such as direct Fick and thermodilution. We compared simultaneously obtained Q̇c measurements during rest and exercise to assess the accuracy and precision of several rebreathing methods. Q̇c measurements were obtained during rest (supine and standing) and stationary cycling (submaximal and maximal) in 13 men and 1 woman (age: 24 ± 7 yr; height: 178 ± 5 cm; weight: 78 ± 13 kg; V̇o2max: 45.1 ± 9.4 ml·kg−1·min−1; mean ± SD) using one-N2O, four-C2H2, one-CO2 (single-step) rebreathing technique, and two criterion methods (direct Fick and thermodilution). CO2 rebreathing overestimated Q̇c compared with the criterion methods (supine: 8.1 ± 2.0 vs. 6.4 ± 1.6 and 7.2 ± 1.2 l/min, respectively; maximal exercise: 27.0 ± 6.0 vs. 24.0 ± 3.9 and 23.3 ± 3.8 l/min). C2H2 and N2O rebreathing techniques tended to underestimate Q̇c (range: 6.6–7.3 l/min for supine rest; range: 16.0–19.1 l/min for maximal exercise). Bartlett's test indicated variance heterogeneity among the methods ( P < 0.05), where CO2 rebreathing consistently demonstrated larger variance. At rest, most means from the noninvasive techniques were ±10% of direct Fick and thermodilution. During exercise, all methods fell outside the ±10% range, except for CO2 rebreathing. Thus the CO2 rebreathing method was accurate over a wider range (rest through maximal exercise), but was less precise. We conclude that foreign gas rebreathing can provide reasonable Q̇c estimates with fewer repeat trials during resting conditions. During exercise, these methods remain precise but tend to underestimate Q̇c. Single-step CO2 rebreathing may be successfully employed over a wider range but with more measurements needed to overcome the larger variability.

A Green Liquid Chromatographic Method For The Simultaneous Determination of Chlorpheniramine Maleate, Pseudoephedrine Hydrochloride and Propyphenazone

2019 ◽  
Vol 15 (6) ◽  
pp. 635-641
Author(s):  
Nadia M. Mostafa ◽  
Ghada M. Elsayed ◽  
Nagiba Y. Hassan ◽  
Dina A. El Mously
Keyword(s):  
Simultaneous Determination ◽  
Mobile Phase ◽  
Dosage Form ◽  
Chromatographic Method ◽  
Green Analytical Chemistry ◽  
Chlorpheniramine Maleate ◽  
Accuracy And Precision ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Background:The concept of green analytical chemistry prevails due to the growing environmental pollution.Objective:Our attempts are to develop simple and eco-friendly method which is non-harmful to the environment by producing minimal waste. In this context, a green liquid chromatographic method was applied for the simultaneous determination of chlorpheniramine maleate, pseudoephedrine hydrochloride and propyphenazone in their combined dosage form.Methods:Separation was carried out using X select HSS RP C18 analytical column (250 × 4.6 mm, 5μm) using methanol - 0.02 M phosphate buffer pH 3 - triethylamine (60:40: 0.1, by volume) as a mobile phase. The separated peaks were detected at 215 nm at a flow rate 1.0 mL/min.Results:Quantification was done over the concentration ranges of 1-25 µg/mL for chlorpheniramine maleate, 5-35 µg/mL for pseudoephedrine hydrochloride and 10-120 µg/mL for propyphenazone. The suggested method was validated with regard to linearity, accuracy and precision according to the International Conference on Harmonization guidelines with good results.Conclusion:It could be used as a safer alternative for routine analysis of the mentioned drugs in quality control laboratories.

scholarly journals Simultaneous determination of iron and copper in children's sera by FAAS

2011 ◽  
Vol 61 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Svjetlana Luterotti ◽  
Tončica Kordić ◽  
Slavica Dodig
Keyword(s):  
Atomic Absorption ◽  
Simultaneous Determination ◽  
Sample Pretreatment ◽  
Single Step ◽  
Design Experiment ◽  
New Approach ◽  
Flame Atomic Absorption ◽  
Reference Methods ◽  
Atomic Absorption Spectrometric

Simultaneous determination of iron and copper in children's sera by FAASA new and simple flame atomic-absorption spectrometric (FAAS) method is proposed for simultaneous determination of iron and copper in children's sera. It is based on single-step sample pretreatment (deproteinization with 3 mol L-1HCl, ratio 1:1) and single-step calibration using 1.5 mol L-1HCl standard. During method's optimization a short multifactorial design experiment was used. The proposed method assures accuracy, sensitivity and precision comparable to that of the reference methods. The new approach is simple and time-, labour- and serum-saving, the latter being especially important in pediatric diagnostics.

scholarly journals Noninvasive Assessment of Cardiac Output: Accuracy and Precision of the Closed‐Circuit Acetylene Rebreathing Technique for Cardiac Output Measurement

2020 ◽  
Vol 9 (17) ◽  
Author(s):  
E. Ashley Hardin ◽  
Douglas Stoller ◽  
Justin Lawley ◽  
Erin J. Howden ◽  
Michinari Hieda ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Coefficient Of Variation ◽  
Clinical Disease ◽  
Closed Circuit ◽  
Stress Tests ◽  
Healthy Individuals ◽  
Output Measurement ◽  
Disease States ◽  
Accuracy And Precision ◽  
Rebreathing Method

Background Accurate assessment of cardiac output is critical to the diagnosis and management of various cardiac disease states; however, clinical standards of direct Fick and thermodilution are invasive. Noninvasive alternatives, such as closed‐circuit acetylene (C 2 H 2 ) rebreathing, warrant validation. Methods and Results We analyzed 10 clinical studies and all available cardiopulmonary stress tests performed in our laboratory that included a rebreathing method and direct Fick or thermodilution. Studies included healthy individuals and patients with clinical disease. Simultaneous cardiac output measurements were obtained under normovolemic, hypovolemic, and hypervolemic conditions, along with submaximal and maximal exercise. A total of 3198 measurements in 519 patients were analyzed (mean age, 59 years; 48% women). The C 2 H 2 method was more precise than thermodilution in healthy individuals with half the typical error (TE; 0.34 L/min [ r =0.92] and coefficient of variation, 7.2%) versus thermodilution (TE=0.67 [ r =0.70] and coefficient of variation, 13.2%). In healthy individuals during supine rest and upright exercise, C 2 H 2 correlated well with thermodilution (supine: r =0.84, TE=1.02; exercise: r =0.82, TE=2.36). In patients with clinical disease during supine rest, C 2 H 2 correlated with thermodilution ( r =0.85, TE=1.43). C 2 H 2 was similar to thermodilution and nitrous oxide (N 2 O) rebreathing technique compared with Fick in healthy adults (C 2 H 2 rest: r =0.85, TE=0.84; C 2 H 2 exercise: r =0.87, TE=2.39; thermodilution rest: r =0.72, TE=1.11; thermodilution exercise: r =0.73, TE=2.87; N 2 O rest: r =0.82, TE=0.94; N 2 O exercise: r =0.84, TE=2.18). The accuracy of the C 2 H 2 and N 2 O methods was excellent ( r =0.99, TE=0.58). Conclusions The C 2 H 2 rebreathing method is more precise than, and as accurate as, the thermodilution method in a variety of patients, with accuracy similar to an N 2 O rebreathing method approved by the US Food and Drug Administration.

Evaluation of a modified acetylene rebreathing method for the determination of cardiac output

1986 ◽  
Vol 6 (3) ◽  
pp. 253-268 ◽  
Author(s):  
J. Nyström ◽  
F. Celsing ◽  
P. Carlens ◽  
B. Ekblom ◽  
P. Ring
Keyword(s):  
Cardiac Output ◽  
Rebreathing Method

Effect of analyzer on determination of mixed venous PCO2 and cardiac output during exercise

1995 ◽  
Vol 79 (3) ◽  
pp. 1032-1038 ◽  
Author(s):  
L. Hornby ◽  
A. L. Coates ◽  
L. C. Lands
Keyword(s):  
Cardiac Output ◽  
Gas Mixture ◽  
Arterial Pco2 ◽  
Venous Pco2 ◽  
The Face ◽  
High O2 ◽  
Collision Broadening ◽  
Rebreathing Methods ◽  
Mixed Venous

Cardiac output (CO) during exercise can be determined noninvasively by using the indirect Fick CO2-rebreathing technique. CO2 measurements for this technique are usually performed with an infrared analyzer (IA) or mass spectrometer (MS). However, IA CO2 measurements are susceptible to underreading in the face of high O2 concentrations because of collision broadening. We compared an IA (Ametek model CD-3A) with a MS (Marquette model MGA-1100) to see the effect this would have on mixed venous PCO2 (PVCO2) and CO measurements. After calibration with room air and a gas mixture of 5% CO2–12% O2–83% N2, both devices were tested with three different gas mixtures of CO2 in O2. For each gas mixture, IA gave lower CO2 values than did the MS (4.1% CO2: IA, 3.85 +/- 0.01% and MS, 4.13 +/- 0.01%; 9.2% CO2: IA, 8.44 +/- 0.07% and MS, 9.19 +/- 0.01%; 13.8% CO2: IA, 12.57 +/- 0.15% and MS, 13.82 +/- 0.01%). Warming and humidifying the gases did not alter the results. The IA gave lower values than did the MS for eight other medical gases in lower concentrations of O2 (40–50%). Equilibrium and exponential rebreathing procedures were performed. Values determined by the IA were > 10% higher than those determined by the MS for both rebreathing methods. We conclude that all IAs must be checked for collision broadening if they are to be used in environments where the concentration of O2 is > 21%. If collision broadening is present, then either a special high O2-CO2 calibration curve must be constructed, or the IA should not be used for both arterial PCO2 and PVCO2 estimates because it may produce erroneously low PVCO2 values, with resultant overestimation of CO.

scholarly journals Development of a New HPLC Method for the Simultaneous Determination of Ticarcillin and Clavulanic Acid in Pharmaceutical Formulations

2009 ◽  
Vol 92 (4) ◽  
pp. 1089-1094
Author(s):  
Tai-Li Tsou ◽  
Chiu-Wey Lee ◽  
Hsian-Jenn Wang ◽  
Ya-Chung Cheng ◽  
Yu-Tien Liu ◽  
...  
Keyword(s):  
Clavulanic Acid ◽  
Simultaneous Determination ◽  
Flow Rate ◽  
Ammonium Acetate ◽  
Pharmaceutical Formulations ◽  
Hplc Method ◽  
Low Flow ◽  
Hplc Separation ◽  
Accuracy And Precision

Abstract A new HPLC method has been developed and validated for the simultaneous determination of ticarcillin (TIC) and clavulanic acid (CA) in pharmaceutical formulations. The HPLC separation was achieved on a -cyclodextrin column (Cyclobond I, 250 4.6 mm, 5 mm) with methanol16 mM pH 6.0 ammonium acetate buffer (50 + 50, v/v) mobile phase at a flow rate of 0.8 mL/min. Detection was at 220 nm. Validation of the method was performed by evaluating specificity, robustness, accuracy, and precision. The calibration curves were linear in the range of 1100 g/mL for CA and 2200 g/mL for TIC. The LOQs based on the standard regression lines were 0.42 and 1.42 g/mL for CA and TIC, respectively, and the LOD were 0.14 and 0.47 g/mL, respectively. Total recoveries of synthetic mixtures (CA:TIC = 1:10, 1:15, and 1:30) were 99.25100.99 for CA and 99.54100.82 for TIC. Compared with the U.S. Pharmacopeia method, the proposed method has the advantage of a relatively low flow rate and short analysis time. The proposed method was successfully applied for the simultaneous determination of these two drugs in sterilized H2O and 5 dextrose injection solutions.

scholarly journals Rapid Gas Chromatographic Method for Simultaneous Determination of Cholesterol and α-Tocopherol in Eggs

1998 ◽  
Vol 81 (6) ◽  
pp. 1177-1184 ◽  
Author(s):  
Nickos Botsoglou ◽  
Dimitrios Fletouris ◽  
Ioannis Psomas ◽  
Antonios Mantis
Keyword(s):  
Simultaneous Determination ◽  
Chromatographic Method ◽  
Labor Cost ◽  
Precision Data ◽  
Total Analysis Time ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
Total Analysis ◽  
Gas Chromatographic Method

Abstract A new method was developed for simultaneous determination of cholesterol and α-tocopherol in eggs. It involves rapid and simple sample preparation accomplished in one tube and chromatographic separation that does not require derivatization of analytes. Total analysis time per sample is 40 min. Labor, cost, and use of hazardous chemicals are minimized. To ensure selectivity, accuracy, and precision, critical analytical parameters were investigated. Overall recoveries were 98.8 and 99.2% for cholesterol and α-tocopherol, respectively. Linearity was acceptable for both analytes (r = 0.9964 for cholesterol and 0.9996 for α-tocopherol) in the fortification range examined. Precision data based on within-day and between-days variation gave overall relative standard deviations of 2.0% for cholesterol and 7.0% for α-tocopherol.The method was applied successfully for quantitation of cholesterol and α-tocopherol in eggs.

Sign in / Sign up

Export Citation Format

Share Document