The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. All other tests fulfilled the required standards. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l) pH (by 0.01) pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values < 200 mmHg) Hb (by 1.6 g/dl) Hb/CPB (by 0.8 g/dl) and Hct (by 6.5%, but were met for Hct/CPB values). The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K 0.86 for Na 0.99 for pH 0.98 for pCO2 0.99 for pO2 0.93 for HCO3 0.93 for BE 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. Measurement of one set of i-STAT values required 2.5 min. Accuracy was judged according to the national quality standard, which requires test results to lie within the 95% confidence interval of conventional tests.Įach blood specimen was analysed: erroneous results or technical failures did not occur. Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. Depending on the capabilities of a hospital's central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. Clinicians should not use the i-STAT(®) Hb in isolation for clinical decision-making when considering blood transfusion in a situation of 25% or greater blood loss.īlood loss haemoglobin measurement point-of-care.Exact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. The standard deviation of i-STAT(®) Hb was greater after ≥25% estimated total blood volume loss. The i-STAT(®) Hb had an acceptable coefficient of variation, but the Hb levels were lower than those estimated by the laboratory. There was poor correlation between total plasma protein and bias in i-STAT(®) measurements. The mean total plasma protein difference (total plasma protein T=0 minus T=1) was 13.6 g/l (95% confidence interval 10.2 to 17.0). The mean difference between i-STAT(®) and laboratory Hb was -7.6 g/l (standard deviation 6.5) at T=0 and -5.1 g/l (standard deviation 12) at T=1. The coefficient of variation of the paired i-STAT(®) Hb estimates was 2.8% and 2.9% at T=0 and T=1, respectively. Blood tests for i-STAT(®) Hb, laboratory Hb (Sysmex XE-2100(™), Sysmex Corporation, Kobe, Japan) and total plasma proteins were obtained at the start of surgery (T=0) and when an estimated 25% total blood volume loss had occurred (T=1). We investigated the accuracy of i-STAT(®) (Abbott Point of Care Inc., Princeton, NJ, USA) haemoglobin (Hb) measurement in surgical patients with an estimated blood loss of ≥25% of total blood volume.
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