T J Morgan, Z H Endre, D M Kanowski, L I Worthley, R D Jones
{"title":"Siggaard-Andersen算法衍生的p50参数:异常血红蛋白-氧亲和和酸碱干扰的扰动。","authors":"T J Morgan, Z H Endre, D M Kanowski, L I Worthley, R D Jones","doi":"","DOIUrl":null,"url":null,"abstract":"<p><p>The p50 and derived indexes, calculated by using the Siggaard-Andersen algorithm from a single measurement of arterial blood gas tensions and hemoglobin-oxygen saturation, are used to assess tissue oxygen availability in critical illness. We tested the accuracy of the Siggaard-Andersen p50 algorithm over a wide range of pathophysiologic conditions. Blood gases, cooximetry, and calculation of standard and in vivo p50 were performed at multiple saturations, CO2 tensions, and H+ concentrations on blood with normal (standard p50 of 26.1 and 26.7 mm Hg), increased (19.0 and 25.4), and reduced (33.9 and 38.2) hemoglobin-oxygen affinity, as well as on high-affinity blood from two patients with diabetic ketoacidosis (16.7 and 20.8). Log p50 in vivo/pH plots were constructed to determine the Bohr effect. Except in the normal affinity specimens (coefficient of variation < 1.7%), standard p50 values showed high variability (coefficient of variation > 5.9%), with saturation-linked bias and distortion of the Bohr effect. Standard p50 was overestimated by up to 11 mm Hg as saturation approached 97%. Although base deficit correction of the stored specimens (6.9 < pH < 7.1) restored the Bohr effect and improved the accuracy of standard p50 calculations (coefficient of variation = 4.4% and 2.9%), saturation-linked bias persisted. We conclude that Siggaard-Andersen p50 calculations may be misleading when there are disturbances of hemoglobin-oxygen affinity and acid-base balance, owing to changes in shape of the hemoglobin-dissociation curve. When metabolic acidosis occurs with high hemoglobin-oxygen affinity, as can occur in critical illness, indexes derived by the Siggaard-Andersen algorithm on arterial blood may greatly overestimate oxygen availability.</p>","PeriodicalId":23085,"journal":{"name":"The Journal of laboratory and clinical medicine","volume":"126 4","pages":"365-72"},"PeriodicalIF":0.0000,"publicationDate":"1995-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Siggaard-Andersen algorithm-derived p50 parameters: perturbation by abnormal hemoglobin-oxygen affinity and acid-base disturbances.\",\"authors\":\"T J Morgan, Z H Endre, D M Kanowski, L I Worthley, R D Jones\",\"doi\":\"\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>The p50 and derived indexes, calculated by using the Siggaard-Andersen algorithm from a single measurement of arterial blood gas tensions and hemoglobin-oxygen saturation, are used to assess tissue oxygen availability in critical illness. We tested the accuracy of the Siggaard-Andersen p50 algorithm over a wide range of pathophysiologic conditions. Blood gases, cooximetry, and calculation of standard and in vivo p50 were performed at multiple saturations, CO2 tensions, and H+ concentrations on blood with normal (standard p50 of 26.1 and 26.7 mm Hg), increased (19.0 and 25.4), and reduced (33.9 and 38.2) hemoglobin-oxygen affinity, as well as on high-affinity blood from two patients with diabetic ketoacidosis (16.7 and 20.8). Log p50 in vivo/pH plots were constructed to determine the Bohr effect. Except in the normal affinity specimens (coefficient of variation < 1.7%), standard p50 values showed high variability (coefficient of variation > 5.9%), with saturation-linked bias and distortion of the Bohr effect. Standard p50 was overestimated by up to 11 mm Hg as saturation approached 97%. Although base deficit correction of the stored specimens (6.9 < pH < 7.1) restored the Bohr effect and improved the accuracy of standard p50 calculations (coefficient of variation = 4.4% and 2.9%), saturation-linked bias persisted. We conclude that Siggaard-Andersen p50 calculations may be misleading when there are disturbances of hemoglobin-oxygen affinity and acid-base balance, owing to changes in shape of the hemoglobin-dissociation curve. When metabolic acidosis occurs with high hemoglobin-oxygen affinity, as can occur in critical illness, indexes derived by the Siggaard-Andersen algorithm on arterial blood may greatly overestimate oxygen availability.</p>\",\"PeriodicalId\":23085,\"journal\":{\"name\":\"The Journal of laboratory and clinical medicine\",\"volume\":\"126 4\",\"pages\":\"365-72\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1995-10-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Journal of laboratory and clinical medicine\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of laboratory and clinical medicine","FirstCategoryId":"1085","ListUrlMain":"","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Siggaard-Andersen algorithm-derived p50 parameters: perturbation by abnormal hemoglobin-oxygen affinity and acid-base disturbances.
The p50 and derived indexes, calculated by using the Siggaard-Andersen algorithm from a single measurement of arterial blood gas tensions and hemoglobin-oxygen saturation, are used to assess tissue oxygen availability in critical illness. We tested the accuracy of the Siggaard-Andersen p50 algorithm over a wide range of pathophysiologic conditions. Blood gases, cooximetry, and calculation of standard and in vivo p50 were performed at multiple saturations, CO2 tensions, and H+ concentrations on blood with normal (standard p50 of 26.1 and 26.7 mm Hg), increased (19.0 and 25.4), and reduced (33.9 and 38.2) hemoglobin-oxygen affinity, as well as on high-affinity blood from two patients with diabetic ketoacidosis (16.7 and 20.8). Log p50 in vivo/pH plots were constructed to determine the Bohr effect. Except in the normal affinity specimens (coefficient of variation < 1.7%), standard p50 values showed high variability (coefficient of variation > 5.9%), with saturation-linked bias and distortion of the Bohr effect. Standard p50 was overestimated by up to 11 mm Hg as saturation approached 97%. Although base deficit correction of the stored specimens (6.9 < pH < 7.1) restored the Bohr effect and improved the accuracy of standard p50 calculations (coefficient of variation = 4.4% and 2.9%), saturation-linked bias persisted. We conclude that Siggaard-Andersen p50 calculations may be misleading when there are disturbances of hemoglobin-oxygen affinity and acid-base balance, owing to changes in shape of the hemoglobin-dissociation curve. When metabolic acidosis occurs with high hemoglobin-oxygen affinity, as can occur in critical illness, indexes derived by the Siggaard-Andersen algorithm on arterial blood may greatly overestimate oxygen availability.