Technical Bulletin, Pronto-7 Accuracy - Masimo

More documents

Recommendations

Info

Pronto-7 Accuracy 25% 20% Frequency of Occurence (%) 15% 10% 5% 0% -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 Difference between Pronto-7 SpHb and Laboratory Reference tHb (g/dL) Figure 3. Normal Sensitivity Mode: Histogram of the Pronto-7 SpHb measurements vs. venous tHb measurements on the Beckman Coulter Model LH500 (N=11,335) 25% 20% Frequency of Occurence (%) 15% 10% 5% 0% -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 Difference between Pronto-7 SpHb and Laboratory Reference tHb (g/dL) Figure 4. Maximum Sensitivity Mode: Histogram of the Pronto-7 SpHb measurements vs. venous tHb measurements on the Beckman Coulter Model LH500 (N=12,622) STUDY #2: accuracy of the PRONTO-7 pulse co-oximeter IN OUTPATIENT SETTING Methods All data was collected under institutional review board approval and all patients provided written, informed consent. Study subjects were adult and pediatric patients presenting to two outpatient clinics and one health screening event. Following written informed consent, patient demographics (age, gender, body mass index, ethnicity, smoking status, and skin pigmentation), medical condition, and medications were recorded for each patient. The Massey and Martin NIS Skin Color Scale 7 was used to categorize skin pigmentation with light pigmentation considered to be 1-3, medium pigmentation 4-7, and dark pigmentation 8-10. Following measurement and recording of finger diameter, a noninvasive hemoglobin test device (Pronto-7, Masimo Corporation, Irvine CA) with a reusable finger clip sensor (rainbow 4D) was placed on the patient’s non-dominant ring finger. The sensor was covered with an opaque shield to prevent
Technical Bulletin optical interference. Two consecutive noninvasive total hemoglobin (SpHb) readings were obtained from each subject, detaching and reattaching the sensor between each measurement. Perfusion index, finger temperature, and SpO2, displayed by the noninvasive hemoglobin test device, were also recorded. Testing was conducted while patients were still, quiet and sitting upright with their hands on the tabletop. Immediately following the noninvasive testing, a venous blood sample was obtained by venipuncture of the median cubital vein of the non-dominant arm (when obtainable) with a disposable syringe and then transferred to 2-mL vacuum tube containing EDTA (Ethylene-DiamineTetraacetic Acid), an anticoagulant. Venous blood samples were transported at room temperature and analyzed for reference hemoglobin (tHb) with an automated hematology analyzer (Coulter ® LH 500, Beckman Coulter, USA 6 ) per Clinical and Laboratory Standards Institute guidelines 8 and the manufacturer’s directions for use, within 24 hours of collection. The laboratory analyzer was calibrated daily per the manufacturer’s recommendations and good laboratory practice. The laboratory hematology analyzer used in this study measures hemoglobin by lysing red blood cells then converting the hemoglobin to a stable pigment. The mass of the hemoglobin in the sample is then determined by the degree of absorbance of the pigment. The accuracy of this method has been validated compared to the hemoglobincyanide method, the reference method for hemoglobinometry recommended by the International Committee for Standardization in Hematology (ICSH). 9 A capillary blood sample was obtained by finger-stick with a 2.25 finger lancet and analyzed immediately with a point of care hemoglobinometer (HemoCue ® 201+, HemoCue a division of Quest Diagnostics, Cypress, CA 10 ) according to the manufacturer’s directions for use. The HemoCue is a photometric device that uses microcuvettes that contain three reagents to lyse red blood cells then convert hemoglobin into methemoglobinazide. The absorbance of methemoglobinazide is then measured to estimate total hemoglobin. 11 The precision of HemoCue for the measurement of hemoglobin varies depending on the type of sample. HemoCue is reported to overestimate hemoglobin from capillary samples by 10-15% compared to the hemoglobincyanide method. 12 Accuracy of SpHb and total hemoglobin by the point of care device (POC-tHb) was assessed by calculating bias and standard deviation of each test method compared to laboratory tHb. To assess repeatability of SpHb measurement, precision (coefficient of variation) between the first and second SpHb measurements was calculated. Precision was calculated as the standard deviation of the difference between the two SpHb test results divided by the mean SpHb value multiplied by 100 and expressed as a percent. Lastly, multivariate analysis was conducted to evaluate the associations of patient characteristics to SpHb-tHb bias. Variables analyzed were body mass index, age, finger diameter, perfusion index, SpO2, finger temperature, ethnicity, skin pigment, smoking status, comorbidities (high blood pressure, diabetes, high cholesterol, respiratory disorders, osteoarthritis) and medications. Multiple logistic regression was performed with significant predictors from the univariate analyses (p≥0.05) to determine main effects and interactions in a multivariate model. For retention in the model a cut off of p≤0.01 was used. Results A total of 474 subjects were enrolled. 34 subjects were excluded for the following reasons: 31 venous samples were not properly transported and unable to obtain 3 noninvasive SpHb measurements. Of the remaining 440 subjects, 62% were male, had an average age (±SD) of 36 (±18) years. Four hundred thirty subjects (98%) were from outpatient clinics and 10 (2%) were from a community health screening event. Subjects consisted of 257 (58%) healthy volunteers and 183 (42%) outpatients presenting with one or more conditions. The number and percent of the outpatients affected with the most common conditions were 72 (16%) with diabetes, 68 (15%) with high cholesterol, 32 (7%) with high blood pressure, 21 (5%) with asthma, 17 (4%) with osteoarthritis, 13 (3%) with chronic obstructive pulmonary disease, and 3 (1%) with pregnancy. Patients had one or more conditions. A total of 369 (84%) of all subjects had light pigmentation, 64 (15%) had medium pigmentation, and 7 (2%) had dark pigmentation. Patient demographics, medical conditions, and medications are shown in Table 4. Univariate and Multivariate Analysis of Factors Associated with SpHb Bias Variables with both univariate and multivariate significance included Massey scale score and SpO2. For each increase in Massey scale, SpHb bias increased by 0.16 g/dL. Higher biases were observed in darker pigmented patients (Massey scale score of 4-9) but the number of subjects in this group was small. For each decrease in SpO2 value, SpHb bias decreased by 0.14 g/dL. Subjects with SpO2 of 96% or below therefore had a negative bias.
Page 1 and 2: Technical Bulletin Accuracy of Noni
Page 3: Technical Bulletin Table 3. SpHb Pe
Page 7 and 8: Technical Bulletin Table 6. Perform

Technical Bulletin, Pronto-7 Accuracy - Masimo

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?