Comparison of haemoglobin values measured at point of care with the standard laboratory value
| dc.contributor.advisor | Marwick, Peter | en_ZA |
| dc.contributor.author | Johnson, Marianne | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Health Sciences. Dept. of Anaesthesiology and Critical Care. | en_ZA |
| dc.date.accessioned | 2016-12-22T13:42:52Z | |
| dc.date.available | 2016-12-22T13:42:52Z | |
| dc.date.issued | 2016-12 | |
| dc.description | Thesis (MMed)--Stellenbosch University, 2016. | en_ZA |
| dc.description | The published article for this thesis is available at http://hdl.handle.net/10019.1/125232 | |
| dc.description.abstract | ENGLISH ABSTRACT: Point of care (POC) haemoglobin (Hb) concentration estimations guide acute decisions on red blood cell transfusion. We studied the accuracy of three POC devices when compared to central laboratory Hb testing and how between-method Hb disagreements could affect the decision to transfuse. The Health Research Ethics Committee of the University of Stellenbosch approved a method comparison study of perioperative Hb concentration measurement in arterial blood sampled from 58 adult cardiothoracic surgery patients. The Hb concentration was measured by using two Ilex GEM PremierTM 3500 blood gas analysers (Blood gas A and Blood gas B), a HemoCue® Hb 201+ System (HemoCue), and our central laboratory’s Siemens Advia® 2120 flow cytometry system (Laboratory haemoglobin). We regarded that a between-method Hb difference exceeding 10% (1 g/dL at an Hb value of 10 g/dL), would likely erroneously influence the transfusion decision. Furthermore, one unit of packed red blood cells will increase the Hb by ±1 g/dL and clinically represents the smallest transfusion associated risk that a patient will be exposed to. From the 58 patients included in the study, 70 central laboratory Hb concentration (Laboratory haemoglobin) measurements and 58, 72, and 71 measurements by the HemoCue, blood gas analyser A (Blood gas A) and blood gas analyser B (Blood gas B), respectively were taken. We found that the mean POC (HemoCue, Blood gas A, and Blood gas B) Hb levels underestimated the mean central laboratory Hb level by 0.79 g/dL, 0.81 g/dL, and 0.67 g/dL, respectively. The 95% confidence interval (CI) of the between-method difference revealed that unlike the Blood gas A (0.43 to 1.15 g/dL) and Blood gas B (0.46 to 1.16 g/dL) values, the HemoCue (0.47 to 0.87 g/dL) values did not breach the predetermined 1 g/dL limit. A Bland-Altman analysis revealed similar between-method mean Hb differences. However, the HemoCue upper and lower limits of agreement (LOA) were narrower, and the 95% CI of the LOAs do not overlap with those of Blood gas A and Blood gas B. Overall the HemoCue is more accurate. Also, the 95% CI of the HemoCue’s lower LOA was below 1 g/dL. This device does not give readings that clinically overestimate the Laboratory haemoglobin. Similarly, the mountain plot demonstrates the greater agreement and precision of the HemoCue device, as compared to Blood gas A and Blood gas B. An error grid analysis focused on the Hb 6 to 10 g/dL clinical decision-making range where only a 10% error was permitted. The error grid analysis revealed that the HemoCue and blood gas analysers had potential transfusion errors of less than 5% and more than 20%, respectively. However, none of the evaluated devices produced values in the major therapeutic error zone, where a decision to transfuse or not transfuse blood will be made erroneously. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Punt van behandeling toetsing van hemoglobien (Hb) konsentrasies rig tydige besluitneming aangaande rooibloedseltransfusies. Ons het die akuraatheid van drie punt van behandeling toestelle ondersoek en vergelyk met die sentrale laboratoriumwaardes en hoe dit die besluit om te transfuseer kon beïnvloed. Toestemming om ‘n metode vergelykende studie uit te voer is van die Gesondheidsnavorsing Etiese Komitee van die Universiteit van Stellenbosch verkry. Arteriële bloedmonsters is geneem van 58 volwasse pasiënte wat kardiotorakschirurgie ondergaan het. Hemoglobien konsentrasies is bepaal met twee Ilex GEM PremierTM 3500 bloedgas analiseerders (Blood gas A en Blood gas B), ‘n HemoCue® Hb 201+ System (HemoCue) en die sentrale laboratorium se Siemens Advia® 2120 vloeisitometrie sisteem (Laboratory haemoglobin). ‘n Tussen-metode verskil van meer as 10% (1 g/dL teen ‘n Hb waarde van 10 g/dL) is gebruik om ‘n noemenswaardige verskil aan te dui aangesien so ‘n fout die besluit om te transfuseer moontlik verkeerdelik kan beïnvloed. Ook vermeerder een eenheid gepakte rooibloedselle die Hb waarde met ongeveer 1 g/dL en verteenwoordig klinies die kleinste transfusie geassosieerde risiko waaraan ‘n pasiënt blootgestel word. Van die 58 pasiënte wat in die studie ingesluit is, is 70 laboratorium Hb meetings en 58, 72 en 71 meetings van die HemoCue, Blood gas A en Blood gas B onderskeidelik geneem. Ons het bevind dat die punt van behandeling toestelle (HemoCue, Blood gas A en Blood gas B) die gemiddelde laboratorium Hb waardes onderskat het met onderskeidelik 0.79 g/dL, 0.81 g/dL en 0.67 g/dL. Die 95% vertrouensinterval van die tussen-metode verskil het aangedui dat die Blood gas A (0.43 tot 1.15 g/dL) en Blood gas B (0.46 tot 1.16 g/dL) die voorafbepaalde 1 g/dL limiet oorskrei. Die HemoCue, hierteenstaande, het nie die limiet oorskrei nie (0.47 tot 0.87 g/dL). Hierdie bevindinge is bevestig met ‘n Bland-Altman analise. Die boonste en onderste limiete van ooreenstemming (LOA) van die HemoCue was egter nouer as die van die Blood gas A en Blood gas B en die 95% vertrouensinterval van die LOA oorvleuel nie met die van Blood gas A en Blood gas B nie. In die geheel beskou is die HemoCue meer akkuraat.Verder is die HemoCue se 95% vertrouensinterval vir die onderste limiet minder as 1 g/dL. Hierdie toestel se resultate het dus nie die sentrale laboratorium se Hb waarde klinies oorskat nie. Die verspreidings diagram (mountain plot) demonstreer ook die beter ooreenstemming en akkuraatheid van die HemoCue toestel in vergelyking met die van Blood gas A en Blood gas B. ‘n ‘Error grid analysis’ het gefokus op die Hb 6 tot 10 g/dL klinies belangrike reikwydte waar slegs ‘n 10% fout toelaatbaar is. Weereens was die HemoCue meer akuraat met potensiële transfusie foute van minder as 5% teenoor die bloedgas analiseerders se meer as 20% potensiële foute. Geen waardes het egter in die major terapeutiese foutsone geval waar ‘n besluit om te transfuseer al dan nie tot skade vir die pasiënt kan lei nie. | af_ZA |
| dc.format.extent | ix, 34 : illustrations | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/100344 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Erythrocytes -- Transfusion | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.subject | Cardiac surgery -- Patients | en_ZA |
| dc.subject | Blood gases -- Analysis | en_ZA |
| dc.title | Comparison of haemoglobin values measured at point of care with the standard laboratory value | en_ZA |
| dc.type | Thesis | en_ZA |