Calculation of bovine haemoglobin oxygen saturation by algorithms integrating age, haemoglobin content, blood pH, partial pressures of oxygen and carbon dioxide in the blood, and temperature.
ABSTRACT In human and veterinary medicine, arterial and venous haemoglobin oxygen saturations are often used to estimate the severity of a disease and to guide therapeutic decisions. In veterinary medicine, haemoglobin oxygen saturation (SO(2)) is usually calculated using a blood gas analyser and algorithms developed for humans. It is possible, therefore, that the values obtained in animals may be distorted, particularly in animals with a high haemoglobin oxygen affinity, like young calves. In order to verify this hypothesis, we compared the arterial (SaO(2)) and venous (SvO(2)) haemoglobin oxygen saturations calculated using three different algorithms, and the oxygen exchange fraction (OEF) at the tissue level, which is the degree of haemoglobin desaturation between arterial and venous blood (SaO(2)-SvO(2)), with the values obtained from the whole bovine oxygen equilibrium curve (OEC) determined by a reference method. The blood gas analysers underestimated SvO(2) values; consequently, the OEF was overestimated (by about 10%). Two methods of reducing these errors were assessed. As the haemoglobin oxygen affinity decreases during the first month of life in calves a relationship between PO(2) at 50% haemoglobin saturation (P50) and age was established in order to correct the calculated values of venous and arterial SO(2), taking into account the estimated position of the OEC. This method markedly reduced the error for SvO(2) and OEF. Secondly, the SO(2) was calculated using a mathematical model taking into account the age of the animal and the specific effects of pH, PCO(2), and temperature on the bovine OEC. Using this method, the mean difference between the OEF values calculated using the mathematical model and those calculated by the reference method was close to zero. The errors produced by blood gas analysers can thus be minimised in two ways: firstly, by simply introducing a P50 estimated from the age of the calf into the analyser before the measurement; and secondly, by calculating the SO(2) using a mathematical model applied to the bovine OEC.
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ABSTRACT: To assess in vivo blood oxygen binding in double-muscled calves and dairy calves with conventional muscle conformation. 58 dairy and 48 double-muscled calves. Calves were classified as neonatal (24 hours old) or older calves (2 to 26 days old). Venous and arterial blood samples were collected, and hemoglobin concentration, pH, PCO2, and PO2 were determined. Blood oxygen equilibrium curves (OEC) under standard conditions were constructed, and the oxygen exchange fraction (OEF) and the amount of oxygen released at the tissue level by 100 ml of blood (OEF Vol%) were calculated. In each breed, partial pressure of oxygen at 50% saturation of hemoglobin (P50) under standard conditions was significantly higher in older than in neonatal calves, indicating a right shift in OEC with age. Venous P50 was significantly lower in neonatal double-muscled calves than in neonatal dairy calves, but arterial and venous P50 were significantly higher in older double-muscled calves than in older dairy calves. In double-muscled, but not in dairy, calves, OEF was significantly higher in older than in neonatal calves. In neonatal calves, OEF Vol% was not significantly different between breeds, but OEF Vol% was significantly higher in older double-muscled calves than in older dairy calves. The lower OEF in neonatal double-muscled calves, compared with dairy calves, could contribute to the higher sensitivity of double-muscled calves to hypoxia. Blood oxygen affinity decreased with age, but OEF and OEF Vol% were unchanged with age in dairy calves, whereas they increased with age in double-muscled calves.American Journal of Veterinary Research 04/2000; 61(3):299-304. DOI:10.2460/ajvr.2000.61.299 · 1.21 Impact Factor
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ABSTRACT: To evaluate the initial measurement of arterial oxygen saturation (SaO2) as a predictor of outcome in acute childhood asthma compared with other factors of past and present asthma history. Prospective observational double-blind study. The emergency department of an urban pediatric hospital with a 1988 annual census of 50,000 children. Two hundred eighty children with recurrent wheezing that was diagnosed by a physician as asthma, who presented to the ED with wheezing. SaO2 was measured on arrival in the ED, and a detailed history of the present attack and past asthma was recorded. Children were treated according to then-current practice guidelines. Parents were contacted by telephone to determine the outcome of the attack; a "poor outcome" was defined as admission to hospital or re-presenting with ongoing symptoms to receive medical care if sent home from the ED. A "worst outcome" was defined as receiving IV aminophylline and steroids after failing to respond to repeated bronchodilation and oral steroids. The proportion of children at each percent SaO2 who had a poor outcome increased with decreasing SaO2 (r = .97). Likelihood ratios for a poor outcome were 35 (confidence interval [CI], 11 to 150) for an SaO2 of 91% or less compared with 96% or more and 4.2 (CI, 2.2 to 8.8) for an SaO2 of 92% to 95% compared with 96% or more. An SaO2 of 91% or less predicted with a sensitivity of 100% and a specificity of 84% those children with a worst outcome who required IV therapy. Other factors of current or past asthma history failed to predict outcome. We have shown that in acute childhood asthma, the initial level of SaO2 reflects severity as it predicts the likelihood of poor outcome. This predictive quality of SaO2 is independent of current or past clinical factors.Annals of Emergency Medicine 07/1994; 23(6):1236-41. DOI:10.1016/S0196-0644(94)70347-7 · 4.33 Impact Factor
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ABSTRACT: 1. The entire oxygen dissociation curve (ODC) and the effects of temperature, pH and 2,3-diphosphoglycerate (DPG) on this curve, have been compared in four mammalians: man, dog, horse and cattle. 2. If the oxyphoric capacities are similar between these species (around 1.39 ml O2/gHb), their P50, measured in standard conditions, i.e. at pH 7.4; pCO2 40 mmHg and T 37 degrees C, varies between 23.8 (+/- 0.8) mmHg for the horse, 25.0 (+/- 1.4) mmHg for cattle, 26.6 (+/- 1.2) for man and 28.8 (+/- 2.6) mmHg for the dog. 3. The higher dispersion of the dog's P 50 is due to difference between breeds; in seven breeds investigated, the P 50 ranges from 25.8 (spaniel) to 35.8 (hound). 4. We noted no sex difference in the four species. 5. The DPG level is confirmed to be low in cattle (< 1 mumol/gHb) as compared to man (13.5 +/- 2.1 mumol/gHb), horse (16.9 +/- 1.1 mumol/gHb) and dog (19.4 +/- 2.8 mumol/gHb). 6. The oxygen exchange fraction defined as the difference in vol% between a pO2 of 80 and 35 mmHg is, respectively, 3.6 (+/- 0.6) vol% for cattle, 4.0 (+/- 0.4) vol% for the horse, 5.5 (+/- 0.5) vol% for man and 6.6 (+/- 1.7) vol% for the dog. 7. The position and shape of the ODC, as well as T, DPG and pH effects, indicate that the haemoglobin of man and dog seem better adapted to O2 delivery as compared to the horse and cattle.Comparative Biochemistry and Physiology Part A Physiology 12/1993; 106(4):687-94. DOI:10.1016/0300-9629(93)90382-E · 2.17 Impact Factor