Effect of storage on measurement of ionized calcium and acid-base variables in equine, bovine, ovine, and canine venous blood.

The stability of blood ionized calcium (Ca2+) and acid-base variables in equine, bovine, ovine, and canine venous blood samples (n = 15, in each group) stored at 4 C for 3, 6, 9, 24, or 48 hours was studied. Variables included blood Ca2+ and standard ionized calcium (Ca2+ corrected to pH 7.4) concentrations, pH, blood carbon dioxide and oxygen tensions, base excess, bicarbonate concentration, and total carbon dioxide content. Results indicate that storage of blood samples at 4 C for up to 48 hours, despite appreciable acid-base changes, is associated with less than 1.5% change in equine, bovine, and ovine blood Ca2+ concentrations. Similar changes were observed in canine blood during the first 9 hours' storage. After 24 and 48 hours' storage, clinically relevant decrease (10.5 and 15.5%) in canine blood Ca2+ concentration was measured. Therefore, Ca2+ concentration in equine, bovine, and ovine venous blood samples stored up to 48 hours, and in canine blood samples stored up to 9 hours at 4 C is of diagnostic use.     

Changes in gas composition and acid-base values of venous blood samples stored under different conditions in 4 domestic species

BACKGROUND: The effect of storage temperature and time on blood gas and acid-base values has been investigated intensively in cattle and dogs; however, data are lacking in other species. OBJECTIVE: The aim of our study was to evaluate changes in gas composition and acid-base values in venous blood stored at different temperatures and for different times in 4 domestic species in Italy. METHODS: Blood samples from Comisana sheep (n = 10), Maltese goats (n = 10), Ragusana donkeys (n = 10), and Thoroughbred horses (n = 10) were analyzed after storage at 23 degrees C (room temperature) for 15 minutes (group I), 23 degrees C for 1 hour (group II), 37 degrees C for 8 hours (group III), and 4 degrees C for 24 hours (group IV). Results were analyzed using a 1-way repeated measures ANOVA. RESULTS: In all species no statistically significant differences in pH values were present in samples stored at 4 degrees C for 24 hours. This also was true for PCO2 in all species except the horse. Except for HCO3- concentration in the horse, significant changes in PO2, HCO3- concentration, base excess, and the standard bicarbonate concentration were observed for all species in samples stored at 4 degrees C. In samples stored for only 1 hour at room temperature, significant changes in most analytes were detected. CONCLUSIONS: The results of this study underline the need for rapid assessment of acid-base samples, because any delay, even for 1 hour, may affect the results.     

Sampling and storage of blood for pH and blood gas analysis.

Techniques used in sampling and storage of a blood sample for pH and gas measurements can have an important effect on the measured values. Observation of these techniques and principles will minimize in vitro alteration of the pH and blood gas values. To consider that a significant change has occurred in a pH or blood gas measurement from previous values, the change must exceed 0.015 for pH, 3 mm Hg for PCO2, 5 mm Hg for PO2, and 2 mEq/L for [HCO-3] or base excess/deficit. In vitro dilution of the blood sample with anticoagulant should be avoided because it will alter the measured PCO2 and base excess/deficit values. Arterial samples should be collected for meaningful pH and blood gas values. Central venous and free-flowing capillary blood can be used for screening procedures in normal patients but are subject to considerable error. A blood sample can be stored for up to 30 minutes at room temperature without significant change in acid-base values but only up to 12 minutes before significant changes occur in PO2. A blood sample can be stored for up to 3.5 hours in an ice-water bath without significant change in pH and for 6 hours without significant change in PCO2 or PO2. Variations of body temperatures from normal will cause a measurable change in pH and blood gas values when the blood is exposed to the normal water bath temperatures of the analyzer.     

Effect of time delay and storage temperature on blood gas and acid-base values of bovine venous blood

The aim of this study was to investigate possible changes in the gas composition and acid-base values of bovine venous blood samples stored at different temperatures (+4, 22 and 37 degrees C) for up to 48 h. Five healthy cattle were used in the study. A total of 15 blood samples collected from the animals were allocated into three groups, which were, respectively, then stored in a refrigerator adjusted to +4 degrees C (Group I, n=5), at a room temperature of about 22 degrees C (Group II, n=5) and in an incubator adjusted to 37 degrees C (Group III; n=5) for up to 48 h. Blood gas and acid-base values were analysed at 0 (baseline), 1, 2, 3, 4, 5, 6, 12, 24, 36 and 48 h of storage. A significant decrease (p<0.001) was found, in the pH of the refrigerated blood after 5 h and its maximum decrease was recorded at 48 h as 0.04 unit. There were also significant alterations (p<0.001) in the blood pH of the samples stored at room temperature and in the incubator after 2 and 3 h, respectively. The maximum mean alteration in pCO(2) value for Group I was -0.72 kPa during the assessment, while for groups II and III, maximum alterations in pCO(2) were detected as +2.68 and +4.16 kPa, respectively. Mean pO(2) values increased significantly (p<0.001) for Group I after 24 h and for Group II after 6 h, while a significant decrease was recorded for Group III after 24 h (p<0.001). Base excess (BE) and bicarbonate (HCO(3)) fractions decreased significantly for all the groups during the study, compared to their baseline values. In conclusion, acid-base values of the samples stored at 22 and +4 degrees C were found to be within normal range and could be used for clinical purposes for up to 12 and 48 h, respectively, although there were small statistically significant alterations.     

The effects of ice-water storage on blood gas and acid–base measurements

Objective: To determine the effects of storage of arterial and venous blood samples in ice water on blood gas and acid–base measurements. Design: Prospective, in vitro, laboratory study. Setting: School of veterinary medicine. Subjects: Six healthy dogs. Measurements and main results: Baseline measurements of partial pressure of oxygen (PO₂), partial pressure of carbon dioxide (PCO₂), pH, hemoglobin concentration (tHb), oxyhemoglobin saturation, and oxygen content (ContO₂) were made. Bicarbonate (HCO₃) and standard base excess (SBE) were calculated. Arterial and venous blood samples were separated into 1 and 3 mL samples, anaerobically transferred into 3 mL plastic syringes, and stored in ice water for 6 hours. Measurements were repeated at 15, 30 minutes, and 1, 2, 4, and 6 hours after baseline measurements. Arterial (a) PO₂ increased significantly from baseline after 30 minutes of storage in the 1 mL samples and after 2 hours in the 3 mL samples. Venous (v) PO₂ was significantly increased from baseline after 4 hours in the 1 mL samples and after 6 hours in the 3 mL samples. The pHa significantly decreased after 2 hours of storage in the 1 mL samples and after 4 hours in the 3 mL samples. In both the 1 and 3 mL samples, pHv decreased significantly only after 6 hours. Neither the arterial nor the venous PCO₂ values changed significantly in the 1 mL samples and increased only after 6 hours in the 3 mL samples. No significant changes in tHb, ContO₂, SBE, or HCO₃ were detected. Conclusions: The PO₂ of arterial and venous blood increased significantly when samples were stored in plastic syringes in ice water. These increases are attributable to the diffusion of oxygen from and through the plastic of the syringe into the blood, which occurred at a rate that exceeded metabolic consumption of oxygen by the nucleated cells.     

Construction of acid-base alignment nomograms to estimate buffer base and base-excess concentrations in arterial blood from immature pigs

Acid-base characteristics of a population of immature domestic pigs were used to construct a blood acid-base alignment nomogram with scales to estimate porcine buffer base concentration. The nomogram was based on average plasma bicarbonate concentration of 31.6 mEq/L and plasma albumin and globulin values of 25.4 and 32.2 g/L, respectively. A measurement temperature of 38 C was assumed. Subsequently, this nomogram was used to construct a blood acid-base alignment nomogram with scales to estimate porcine base-excess concentration. The nomogram was based on the assignment of zero-base excess to blood with a pH of 7.50 and a PCO2 of 40 mm of Hg. Construction details, including tabular data reflecting the acid-base characteristics of porcine plasma and erythrocytes, are provided.     

Influence of Fasting on Canine Arterial and Venous Blood Gas and Acid-Base Measurements

Arterial and venous blood gas profiles were obtained from 33 clinically normal adult dogs of two breeds (German Shepherd Dog and English Pointer) 4 and 24 hours after eating. Fresh drinking water was available. All dogs were fed a nutritionally complete and balanced dry diet. Blood gas parameters measured included pH, pCO₂, pO₂, bicarbonate, base excess, total carbon dioxide, oxygen content, and oxygen saturation.
Statistically significant differences (P < 0.01) were found between sampling intervals (4 and 24 hours postprandial) for pCO₂, bicarbonate, total carbon dioxide, and base excess, for arterial and venous blood samples.
Statistically significant differences (P < 0.01) were found between arterial and venous blood for all parameters, at both sampling intervals.
No statistically significant interactions (P > 0.05) were found between sample type (arterial or venous) and sampling interval.
Correlations between arterial and venous samples were generally (but not exclusively) higher than correlations between sampling intervals. Breed differences were also noted.     

Simple acid-base disorders

The body regulates pH closely to maintain homeostasis. The pH of blood can be represented by the Henderson-Hasselbalch equation: pH = pK + log [HCO3-]/PCO2 Thus, pH is a function of the ratio between bicarbonate ion concentration [HCO3-] and carbon dioxide tension (PCO2). There are four simple acid base disorders: (1) Metabolic acidosis, (2) respiratory acidosis, (3) metabolic alkalosis, and (4) respiratory alkalosis. Metabolic acidosis is the most common disorder encountered in clinical practice. The respiratory contribution to a change in pH can be determined by measuring PCO2 and the metabolic component by measuring the base excess. Unless it is desirable to know the oxygenation status of a patient, venous blood samples will usually be sufficient. Metabolic acidosis can result from an increase of acid in the body or by excess loss of bicarbonate. Measurement of the "anion-gap" [(Na+ + K+) - (Cl- + HCO3-)], may help to diagnose the cause of the metabolic acidosis. Treatment of all acid-base disorders must be aimed at diagnosis and correction of the underlying disease process. Specific treatment may be required when changes in pH are severe (pH less than 7.2 or pH greater than 7.6). Treatment of severe metabolic acidosis requires the use of sodium bicarbonate, but blood pH and gases should be monitored closely to avoid an "overshoot" alkalosis. Changes in pH may be accompanied by alterations in plasma potassium concentrations, and it is recommended that plasma potassium be monitored closely during treatment of acid-base disturbances.     

A Comparison of Simultaneously Collected Arterial, Mixed Venous, Jugular Venous and Cephalic Venous Blood Samples in the Assessment of Blood-Gas and Acid-Base Status in the Dog

Blood samples were collected simultaneously from the pulmonary artery, jugular vein, cephalic vein, and carotid artery in awake dogs. Blood-gas and acid-base values were measured from these blood samples in normal dogs and in dogs after production of metabolic acidosis and metabolic alkalosis. The values obtained from each of the venous sites were compared with those obtained from arterial blood to determine if venous blood from various sites accurately reflected acid-base balance and could therefore be used in the clinical patient. The results of this study demonstrated significant differences between the blood from various venous sites and the arterial site for PCO2 and pH in all acid-base states. Significant differences for standard bicarbonate (SHCO3) were found only when jugular and cephalic venous blood were compared with arterial blood in dogs with a metabolic acidosis. No significant differences were found for BE when blood from the venous sites was compared with arterial blood. The values for pH, HCO3, TCO2, BE, and SHCO3 measured on blood collected at the various venous sites were found to correlate well with those obtained from arterial blood, with a correlation coefficient of 0.99 for HCO3, TCO2, BE, and SHCO3. These correlation coefficients, together with similar values in BE at all collection sites, indicate that, in the dog with normal circulatory status, blood from any venous site will accurately reflect the acid-base status of the patient.     

Eperythrozoon infection in swine: effect on the acid-base balance and the glucose, lactate and pyruvate content of venous blood

The influence of latent and of splenectomy-induced clinically manifest Eperythrozoon suis infection on the following parameters of the carbohydrate metabolism and the acid-base status was tested in venous blood of German Landrace pigs: Levels of glucose, lactic and pyruvic acid, blood-pH, base excess, actual bicarbonate concentration, standard bicarbonate concentration, pCO2, pO2. The latent E. suis infection resulted in a consistent decrease of blood glucose level. 23 days after infection, blood glucose was reduced by 25% of the initial value. The other parameters were not changed by latent E. suis infection. Acute Eperythrozoonosis induced severe hypoglycaemia (means Gluc, = 39.7 mg/dl and blood acidosis (means pH = 7.13). In vitro experiments showed that break-down of glucose in E. suis infected blood occurs very rapidly. There was no significant reduction of the glucose concentration in control blood that had been treated accordingly. There was an increase of lactic acid (means = 62.7 mg/dl), pyruvic acid (means = 1.86 mg/dl), and pCO2 (means = 82.1 mm Hg). The concentrations of actual bicarbonate (means = 24.8 mmol/l) and standard bicarbonate (means = 20.9 mmol/l) were lowered, and there was a negative base excess (means = -3.56 mmol/l). The ratio of lactic and pyruvic acid changed from 11:1 to 30:1. It seems likely that E. suis itself is able to metabolize glucose. Acidosis is considered to result from both the increase of lactic acid (metabolic component) and an impairment of pulmonary gas exchange (respiratory component).     

Values of acid-base equilibrium in the blood of various species of domestic animals]

By means of the Astrup equilibration method the values of the acid-base balance of the blood were determined in 104 cows, 99 horses, 100 pigs, 15 sheep, 20 goats, and in 101 dogs. The pH values of the blood, the partial pressure of CO2, the base excess, the base buffer, the standard bicarbonate, the actual bicarbonate, and the total CO2 were processed statistically and are presented in tables.     

Decreased colostral immunoglobulin absorption in calves with postnatal respiratory acidosis

The effect of postnatal acid-base status on the absorption of colostral immunoglobulins by calves was examined in 2 field studies. In study 1, blood pH at 2 and 4 hours after birth was related to serum IgG1 concentration 12 hours after colostrum feeding (P less than 0.05). Decreased IgG1 absorption from colostrum was associated with respiratory, rather than metabolic, acidosis, because blood PCO2 at 2 and 4 hours after birth was negatively related to IgG1 absorption (P less than 0.05), whereas serum bicarbonate concentration was not significantly related to IgG1 absorption. Acidosis was frequently observed in the 30 calves of study 1. At birth, all calves had venous PCO2 value greater than or equal to 60 mm of Hg, 20 of the calves had blood pH less than 7.20, and 8 of the calves had blood bicarbonate concentration less than 24 mEq/L. Blood pH values were considerably improved by 4 hours after birth; only 7 calves had blood pH values less than 7.20. Calves lacking risk factors for acidosis were examined in study 2, and blood pH values at 4 hours after birth ranged from 7.25 to 7.39. Blood pH was unrelated to IgG1 absorption in the calves of study 2. However, blood PCO2 was again found to be negatively related to colostral IgG1 absorption (P less than 0.005). Results indicate that postnatal respiratory acidosis in calves can adversely affect colostral immunoglobulin absorption, despite adequate colostrum intake early in the absorptive period.     

The Effect of Resuscitation Technique and Pre-Arrest State of Oxygenation on Blood–Gas Values during Cardiopulmonary Resuscitation in Dogs

Large mongrel dogs were anesthetized, instrumented, and subjected to electrically induced ventricular fibrillation after breathing either 100% oxygen (O2) or 10% O2 and 90% nitrogen for 10 minutes before arrest. Four minutes after arrest, open chest cardiopulmonary resuscitation (CPR) or intermittent abdominal compression closed chest CPR was initiated and continued for 20 minutes, at which time defibrillation was attempted. Central arterial and mixed venous blood samples were collected serially for the measurement of pH, carbon dioxide partial pressure (PCO2), and O2 partial pressure (PO2), and calculation of bicarbonate concentration and base excess. Mixed venous blood was collected serially for the measurement of lactate concentration. Hemodynamically variable resuscitation techniques and pre-arrest hypoxia or hyperoxia did not significantly influence blood-gas values during CPR. Mixed venous lactate concentrations after 20 minutes of CPR were significantly higher when hypoxia preceded the arrest and when intermittent abdominal compression closed chest CPR was used for resuscitation. Mixed venous PCO2 was significantly higher than arterial PCO2 in all dogs during CPR but was not significantly different before arrest.     

Blood gas and acid-base analysis of arterial blood in 57 newborn calves

The pH, partial pressure of oxygen (pO(2)), partial pressure of carbon dioxide (pCO(2)), concentration of bicarbonate (HCO(3)(-)), base excess and oxygen saturation (SO(2)) were measured in venous and arterial blood from 57 newborn calves from 55 dams. Blood samples were collected immediately after birth and 30 minutes, four, 12 and 24 hours later from a jugular vein and a caudal auricular artery. The mean (sd) pO(2) and SO(2) of arterial blood increased from 45.31 (16.02) mmHg and 64.16 (20.82) per cent at birth to a maximum of 71.89 (8.32) mmHg and 92.81 (2.32) per cent 12 hours after birth, respectively. During the same period, the arterial pCO(2) decreased from 57.31 (4.98) mmHg to 43.74 (4.75) mmHg. The correlation coefficients for arterial and venous blood were r=0.86 for pH, r=0.85 for base excess and r=0.76 for HCO(3)(-). The calves with a venous blood pH of less than 7.2 immediately after birth had significantly lower base excess and HCO(3)(-) concentrations for 30 minutes after birth than the calves with a venous blood pH of 7.2 or higher. In contrast, the arterial pO(2) was higher in the calves with a blood pH of less than 7.2 than in those with a higher pH for 30 minutes after birth.     

Blood acid-base curve nomogram for immature domestic pigs

The purpose in this study was to characterize the acid-base status of arterial blood from healthy young domestic swine and to construct an acid-base curve nomogram appropriate to such animals. Accordingly, 40 immature, 20- to 31-kg domestic pigs were used to establish acid-base characteristics for arterial blood. Samples were collected from chronically implanted catheters while the animals were maintained under steady-state, near-basal conditions. At a measurement temperature of 38 C, pH averaged 7.496; PCO2, 40.6 mm Hg; [HCO3-], 31.6 mEq/L; PO2, 79.1 mm Hg; hemoglobin, 9.65 g/dl; hematocrit, 0.29; plasma albumin, 25.3 g/L; plasma globulin, 32.3 g/L; and plasma buffer base, 45.4 mEq/L. Hourly measurements over a 6-hour period in 6 of these pigs showed a small, but significant decrease in PO2 with time, but no significant change in acid-base status. The data showed that nomograms or other procedures based on blood characteristics of men were invalid when used to estimate base excess concentration of blood from young pigs. The normal pH of arterial blood was higher in immature pigs than in men; thus, reference values defining zero base excess were not equivalent in men and pigs. Constant PCO2 titrations were performed on arterial samples taken from 10 additional pigs, and the data were used to construct an acid-base curve nomogram in which zero base excess was defined for blood with a pH of 7.50 and a PCO2 of 40 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic response of horses to a high soluble carbohydrate diet: effects of low-intensity submaximal exercise and sodium bicarbonate supplementation.

Four mares fed a low fiber, high soluble carbohydrate diet were used in a crossover design to evaluate the effects of dietary sodium bicarbonate (NaHCO3) supplementation during daily low-intensity submaximal working conditions. Mares were fed the diet at 1.7 times the maintenance energy requirement for mature horses at work. The horses tolerated the diet well and had no clinical abnormalities. Resting venous blood bicarbonate (HCO3), standard HCO3, and base excess (BE) concentrations significantly (P less than 0.05) increased with NaHCO3 supplementation, but no significant changes in resting venous blood pH or carbon dioxide tension (PCO2) were recorded. Venous blood HCO3, standard HCO3, BE, hemoglobin, and heart rate were significantly (P less than 0.05) increased and plasma lactate concentration was significantly (P less than 0.05) decreased in the control horses and in the horses given the NaHCO3 supplement during low-intensity submaximal exercise. There were no significant changes in venous blood pH, PCO2, or plasma protein concentration with exercise. Venous blood HCO3, standard HCO3, and BE concentrations were significantly (P less than 0.05) greater during submaximal exercise in horses given the NaHCO3 supplement. There were no significant differences in plasma lactate or total protein concentrations, blood pH, PCO2, or hemoglobin concentration between the 2 groups during exercise.     

Usefulness of Venous Blood in Estimating Acid-Base Status of the Seriously III Dog

The usefulness of venous blood in determining the acid-base status of seriously ill animals has not been investigated. The purpose of this study was to determine whether a useful relationship exists between the acid-base parameters of central venous and arterial blood in ill dogs.
Paired arterial and venous blood samples were obtained from 46 dogs seen in the Critical Care Unit of the Veterinary Teaching Hospital of Colorado State University irregardless of their hemodynamic status. Cardiopulmonary arrest patients were not included in the study.
Results of this study indicate venous blood samples can be used in the assessment of acid-base status. Statistical significance was seen in comparing arterial versus venous pH (P < 0.001), PCO2 (P < 0.001), and bicarbonate (P < 0.001). Linear regression equations will allow one to predict arterial values from venous samples.     

Clinical studies of fish blood: importance of sample collection and measurement techniques

Effects of blood sample collection and measurement techniques were assessed for blood gas tensions, acid-base status, and hematologic and plasma biochemical values of rainbow trout. Blood samples were collected via intraaortic cannulae from immersed, unrestrained fish and from emersed, restrained fish. The samples were analyzed at either fish body temperature (10 to 14 C) or clinical blood analyzer temperature (37 C); results obtained at 37 C were back-adjusted to fish body temperature, using standard mammalian temperature-correction factors. Fish emersion and handling for 30 seconds significantly (P less than 0.05) altered blood PCO2, acid-base status, and hematologic and plasma biochemical values. The results were consistent with respiratory acidosis and hemoconcentration. The use of mammalian temperature-correction factors for determination of fish blood gas tensions and acid-base status yielded values that were significantly (P less than 0.05) different from those measured directly at fish body temperature.     

Accuracy of a portable blood gas analyzer incorporating optodes for canine blood

The accuracy of a portable blood gas analyzer (OPTI 1) was evaluated using canine blood and aqueous control solutions. Sixty-four arterial blood samples were collected from 11 anesthetized dogs and were analyzed for pH, partial pressure of carbon dioxide (PCO2) partial pressure of oxygen (PO2), and bicarbonate concentration ([HCO3-]) values by the OPTI 1 and a conventional blood gas analyzer (GASTAT 3). The conventional analyzer was considered as a standard against which the OPTI 1 was evaluated. Comparison of OPTI 1 results with those of GASTAT 3 by linear regression analysis revealed a high degree of correlation with the GASTAT 3 (r = .90-.91). The mean +/- SD of the differences between OPTI 1 and GASTAT 3 values was -0.008 +/- 0.017 for pH, -0.88 +/- 3.33 mm Hg for PCO2, 3.71 +/- 6.98 mm Hg for PO2, and -0.34 +/- 1.45 mEq/L for [HCO3-]. No statistically significant difference was found between the OPTI 1 and the GASTAT 3. Agreement between these 2 methods is within clinically acceptable ranges for pH, PCO2, PO2, and [HCO3-]. The coefficients of variation for measured pH, PCO2, and PO2 values of 3 aqueous control solutions (acidic, normal, and alkalotic) analyzed by the OPTI 1 ranged from 0.047 to 0.072% for pH, 0.78 to 1.81% for PCO2, and 0.73 to 2.77% for PO2. The OPTI 1 is concluded to provide canine blood gas analysis with an accuracy that is comparable with that of conventional benchtop blood gas analyzers.