The effects of surgery and anesthesia on blood magnesium and calcium concentrations in canine and feline patients

OBJECTIVE: To demonstrate the effect of anesthesia and surgery on serum ionized magnesium and ionized calcium concentrations in clinical canine and feline patients. ANIMALS: 37 client-owned dogs, ASA PS I-III and 10 client-owned cats, ASA PS I, all receiving anesthesia for elective or emergent surgery at a Veterinary Teaching Hospital. MATERIALS AND METHODS: Plasma ionized and serum total magnesium, and plasma ionized calcium were measured prior to and after a group-standardized anesthetic protocol. RESULTS: Regardless of pre-operative medication (hydromorphone or butorphanol), anesthetic induction (thiopental or lidocaine/hydromorphone/diazepam (LHD) and propofol combination), or type of surgical procedure (peripheral surgery or laparotomy), post-operative plasma ionized calcium concentration decreased in all groups of dogs, while post-operative plasma ionized magnesium increased in all groups, although the changes were not always significant. The dogs who were induced with an LHD and propofol technique had a greater increase in ionized magnesium (0.36 +/- 0.07 to 0.42 +/- 0.07 mmol L(-1)) than the group in which anesthesia was induced with thiopental (0.41 +/- 0.07 to 0.42 +/- 0.07 mmol L(-1), p = 0.009). The cats showed similar changes in ionized magnesium and ionized calcium, and also had a significant increase in serum total magnesium (2.17 +/- 0.20 to 2.31 +/- 0.25 mg dL(-1), p = 0.009) CONCLUSIONS, CLINICAL RELEVANCE: A post-operative decrease in ionized calcium was demonstrated in healthy animals, as well as an increase in ionized or total magnesium after various anesthetic protocols and surgeries. These changes, while statistically significant, do not appear to be clinically significant, as values remained within reference ranges at all times.     

Validation of the bovine blood calcium checker as a rapid and simple measuring tool for the ionized calcium concentration in cattle

Point-of-care (POC) devices that veterinary practitioners can use to easily and rapidly measure blood ionized calcium (iCa) levels in cows immediately after withdrawing a blood sample on the dairy farm are needed. Aims of present studies was to compare the commercially available ion-selective electrode handheld iCa meter (bovine blood iCa checker) with the benchtop blood gas analyzer GEM premier 3500 and handheld analyzer i-STAT 1. Sixty-two paired-point whole blood samples were obtained from three cows with hypocalcemia experimentally induced by Na₂-EDTA infusion. Whole blood samples were also obtained from the 36 cows kept on a farm in field conditions. The results using the bovine blood iCa checker correlated with those using the GEM premier 3500 and i-STAT 1. Bovine blood iCa checker was “compatible” with the GEM premier 3500 and i-STAT 1 because the frequency of differences between the measurements within ± 20% of the mean were 100% (65/65, >75%) and 90.8% (59/65, >75%), respectively. In the field trial, the blood iCa concentration measured by the bovine blood Ca checker was significantly positively correlated with that measured by the i-STAT 1 portable analyzer. Bovine blood iCa checker was “compatible” with the i-STAT 1 because the frequency of differences between the measurements within ± 20% of the mean was 100% (36/36, >75%). Results from these findings, the bovine blood iCa checker may be applied as a simplified system to measure the iCa concentration in bovine whole blood.     

Artifactual changes in canine blood following storage, detected using the ADVIA 120 hematology analyzer

BACKGROUND: Artifactual changes in blood may occur as a consequence of delayed analysis and may complicate interpretation of CBC data. OBJECTIVE: The aim of this study was to characterize artifactual changes in canine blood, due to storage, using the ADVIA 120 hematology analyzer. METHODS: Blood samples were collected into EDTA from 5 clinically healthy dogs. Within 1 hour after blood sample collection and at 12, 24, 36 and 48 hours after storage of the samples at either 4 degrees C or room temperature (approximately 24 degrees C), a CBC was done using the ADVIA 120 and multispecies software. A linear mixed model was used to statistically evaluate significant differences in values over time, compared with initial values. RESULTS: The HCT and MCV were increased significantly after 12 hours of collection at both 4 degrees C and 24 degrees C, and continued to increase through 48 hours. The MCHC initially decreased significantly at 12-24 hours and then continued to decrease through 48 hours at both temperatures. Changes in HCT, MCV, and MCHC were greater at 24 degrees C than at 4 degrees C at all time points. A significant increase in MPV and a decrease in mean platelet component concentration were observed at all time points at 24 degrees C. Samples stored at 24 degrees C for 48 hours had significantly higher percentages of normocytic-hypochromic RBCs, and macrocytic-normochromic RBCs, and lower platelet and total WBC counts. CONCLUSIONS: Delayed analysis of canine blood samples produces artifactual changes in CBC results, mainly in RBC morphology and platelet parameters, that are readily detected using the ADVIA 120. Refrigeration of specimens, even after 24 hours of storage at room temperature, is recommended to improve the accuracy of CBC results for canine blood samples.     

Serum ionized calcium in dogs with chronic renal failure and metabolic acidosis

BACKGROUND: Chronic renal failure (CRF) is a common disease in dogs, and many metabolic disorders can be observed, including metabolic acidosis and calcium and phosphorus disturbances. Acidosis may change the ionized calcium (i-Ca) fraction, usually increasing its concentration. OBJECTIVE: In this study we evaluated the influence of acidosis on the serum concentration of i-Ca in dogs with CRF and metabolic acidosis. METHODS: Dogs were studied in 2 groups: group I (control group = 40 clinically normal dogs) and group II (25 dogs with CRF and metabolic acidosis). Serum i-Ca was measured by an ion-selective electrode method; other biochemical analytes were measured using routine methods. RESULTS: The i-Ca concentration was significantly lower in dogs in group II than in group I; 56% of the dogs in group II were hypocalcemic. Hypocalcemia was observed in only 8% of dogs in group II when based on total calcium (t-Ca) concentration. No correlation between pH and i-Ca concentration was observed. A slight but significant correlation was detected between i-Ca and serum phosphorus concentration (r = -.284; P = .022), as well as between serum t-Ca and i-Ca concentration (r = .497; P < .0001). CONCLUSION: The i-Ca concentration in dogs with CRF and metabolic acidosis varied widely from that of t-Ca, showing the importance of determining the biologically active form of calcium. Metabolic acidosis did not influence the increase in i-Ca concentration, so other factors besides acidosis in CRF might alter the i-Ca fraction, such as hyperphosphatemia and other compounds that may form complexes with calcium.     

Overestimation of canine albumin concentration with the bromcresol green method in heparinized plasma samples

Albumin concentrations are routinely measured in dogs with bromcresol green (BCG)-binding assays on automated chemistry analyzers. Several variables affect this assay, including the length of reaction time, sample type, and lack of specificity of BCG for albumin. We observed that albumin concentrations measured with BCG appeared higher in heparinized plasma samples in sick dogs. The objective of this study was to determine the effect of anticoagulant and assay procedure on BCG albumin concentrations in clinically ill dogs. We hypothesized that albumin concentrations would be overestimated in heparinized plasma compared with serum because of the combination of heparin and fibrinogen. Furthermore, we hypothesized that the overestimation would be influenced by assay parameters. Blood was collected from 32 clinically ill dogs into tubes containing heparin, citrate, or no anticoagulant. Citrate was chosen to assess the effect of fibrinogen in the absence of heparin. Albumin concentration was measured in all 3 sample types from each dog using 2 different BCG procedures on an automated chemistry analyzer. The BCG procedures (standard and modified) differed in the wavelengths used for absorbance readings (standard, 600/700; modified, 570/505) and the time point at which absorbance was measured (standard, 100 seconds; modified, 40 seconds). In addition, the modified method incorporated a sample blank. Globulin fractions, fibrinogen concentration, and indices of lipemia, hemolysis, and icterus were evaluated for their contribution to the overestimation of albumin concentration in heparinized plasma compared with serum samples. Albumin concentrations were significantly higher (P 相似文献   

The concentration of ionized magnesium in serum during the periparturient period of non-paretic dairy cows

Ion-selective electrodes have recently been designed for determining the ionized concentration of magnesium (Mg²⁺) in serum. This development may allow new insights into some metabolic diseases of cattle. For this report, the concentrations of Mg²⁺, total magnesium (Mg_tot), ionized calcium (Ca²⁺), total calcium (Ca_tot), and inorganic phosphate (P_i) were determined in sera from seventeen 3-to 16-year-old Brown Swiss and crossed Simmental/Red Holstein cows during the periparturient period. In each animal, a transient increase of Mg²⁺ and Mg_tot serum concentrations was observed in association with the transient decrease in serum concentrations of Ca²⁺, Ca_tot and P_i after parturition. On average, throughout the study, the serum Mg²⁺ concentrations were 68.5% of those of Mg_tot, whereas the serum Ca²⁺ concentrations were 52% of those of Ca_tot. The possible mechanisms involved in the transient increase of Mg²⁺ and Mg_tot serum concentrations are discussed.Abbreviations Ca²⁺ ionized calcium - Ca_tot total calcium - Mg²⁺ ionized magnesium - Mg_tot total magnesium - P_i inorganic phosphate - PTH parathyroid hormone - PTHrP parathyroid homrone related protein     

Studies on ionized calcium in serum and plasma from normal cows. Its relation to total serum calcium and the effects of sample storing.

Ionized calcium has been determined with a new improved instrument on serum samples from 111 Swedish red-and-white cows. Simultaneous sampling of plasma and serum was performed in 32 cows for comparison of the ionized calcium level. Multiple sampling of plasma and serum from seven cows was performed to evaluate the effect of storage at 4°C and room temperature.The normal range for ionized calcium found in this study implies that the ionized calcium fraction comprises for 43.4 ± 3.0 % (mean ± 2 s) of the total serum calcium. Simultaneous analyses on plasma and serum revealed that the plasma level of ionized calcium was generally 0.ι05 mιmol/1 lower than the serum value. pH changes in stored blood samples have a direct effect on the ionized calcium levels and is therefore to be avoided. Storing samples in vacutainers for five days at 4°C or for two days at room temperature was accompanied by only small decreases of serum or plasma ionized calcium.The new instrument used in this study enables rapid analyses, and most of earlier drawbacks with calcium-ion-selective analyzers have been eliminated.     

Retrospective Study: Incidence of ionized hypocalcemia in septic dogs and its association with morbidity and mortality: 58 cases (2006–2007)

Objective – To determine the incidence rate and prognostic significance of ionized hypocalcemia (iHCa) among septic dogs. Design – Retrospective study Setting – Veterinary teaching hospital Animals – Fifty‐eight septic dogs that were presented to Cornell University Hospital for Animals between January 2006 and December 2007. Procedure – Cases were diagnosed with sepsis if they exhibited 2 or more criteria of the systemic inflammatory response syndrome with a concurrent documented infectious focus. Cases were excluded if diagnosed with a concurrent illness reportedly associated with calcium derangements. Lowest, mean, and highest blood ionized calcium concentrations were recorded and statistically analyzed for an association with morbidity, as measured by duration of hospitalization and number of blood product transfusions, and outcome. In addition, the incidence rate of iHCa was recorded. Results – Of the 58 cases included in this study, iHCa was documented in 4 of 6 (67%) patients that died, 5 of 19 (26%) euthanized patients and 5 of 33 (15%) patients that survived to discharge, with an overall incidence of 24%. Dogs that died during hospitalization had more severe iHCa than patients that were discharged or euthanized as well as significantly lower mean ionized calcium concentrations than patients who were discharged. Severity of iHCa was also associated with a longer duration of hospitalization. The highest ionized calcium concentration was not associated with outcome. Conclusion and Clinical Relevance – This study is the first to document the incidence of iHCa among septic dogs. Because both low mean ionized calcium and the lowest documented ionized calcium concentration are associated with poor outcome, it is likely that both the severity and duration of hypocalcemia are important in these patients. Further prospective studies investigating the prognostic significance, etiology and treatment of iHCa among septic veterinary patients are needed to better understand its role in sepsis.     

Comparative analysis of haematological, haemostatic, and inflammatory parameters in canine venous and arterial blood samples

The objective of the present study was to validate the use of blood collected from an indwelling arterial catheter for analysis of haematological, coagulation and inflammatory parameters in canines compared to venous blood collected directly from the jugular vein. Blood samples were collected from 11 dogs. Agreement between sampling methods was found for neutrophil and monocyte counts, prothrombin time, activated partial thromboplastin time, antithrombin, protein C, factor VIII and C-reactive protein, whereas a statistically significant difference was found for white blood cells, lymphocyte, erythrocyte and platelet counts, haemoglobin, haematocrit, fibrinogen and thrombin time (TT). In conclusion, it is necessary to be aware that results from a complete blood count obtained from canine venous and arterial blood samples may not be comparable. Values for haemostatic parameters from arterial and venous blood samples, with the exception of fibrinogen and TT, were however statistically identical.     

Evaluation of an Electrolyte Analyser for Measurement of Concentrations of Ionized Calcium and Magnesium in Cats

The goal of this study was to evaluate the Nova CRT 8 electrolyte analyser for determination of concentrations of ionized calcium (Ca_i) and magnesium (Mg_i) in cats, todetermine the effects of sample handling and storage and to establish reference ranges. The precision and analytical accuracy of the Nova CRT 8 analyser were good. The concentrations of Ca_i and Mg_i were significantly lower in aerobically handled serum samples than in those handled anaerobically. The concentrations of Ca_i and Mg_i differed significantly among whole blood, plasma and serum. In anaerobically handled serum, the concentration of Ca_i was stable for 8 h at 22°C, for 5 days at 4°C and for 1 week at −20°C. The concentration of Mg_i was stable for 4 h at 22°C but for less than 24 h at 4°C and for less than 1 week at −20°C. In serum from 36 cats, the reference ranges were 1.20–1.35 mmol/L for Ca_i and 0.47–0.59 mmol/L for Mg_i. The Nova CRT 8 electrolyte analyser is suitable for determination of Ca_i and Mg_i concentrations in cats. Anaerobically handled serum samples are recommended and, stored at room temperature, they yield accurate results when analysed within 4 h.     

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.     

Evaluation of an electrolyte analyzer for measurement of ionized calcium and magnesium concentrations in blood, plasma, and serum of dogs

OBJECTIVE: To evaluate an electrolyte analyzer for measurement of ionized calcium (Ca(i)) and magnesium (Mg(i)) concentrations in blood, plasma, and serum; investigate the effect of various factors on measured values; and establish reference ranges for Ca(i) and Mg(i) in dogs. ANIMALS: 30 healthy adult dogs of various breeds. PROCEDURE: Precision in a measurement series, day-to-day precision, and linearity were used to evaluate the analyzer. The effects of exposure of serum samples to air, type of specimen (blood, plasma, or serum), and storage temperature on sample stability were assessed. Reference ranges were established with anaerobically handled serum. RESULTS: The coefficient of variation for precision in a measurement series was < or = 1.5% for both electrolytes at various concentrations. The Ca(i) and Mg(i) concentrations were significantly lower in aerobically handled serum samples, compared with anaerobically handled samples. The Ca(i) and Mg(i) concentrations differed significantly among blood, plasma, and serum samples. In anaerobically handled serum, Ca(i) was stable for 24 hours at 22 degrees C, 48 hours at 4 degrees C, and 11 weeks at -20 degrees C; Mg(i) was stable for 8 hours at 22 degrees C, < 24 hours at 4 degrees C, and < 1 week at -20 degrees C. In anaerobically handled serum, reference ranges were 1.20 to 1.35 mmol/L for Ca(i) and 0.42 to 0.58 mmol/L for Mg(i). CONCLUSIONS AND CLINICAL RELEVANCE: The electrolyte analyzer was suitable for determination of Ca(i) and Mg(i) concentrations in dogs. Accurate results were obtained in anaerobically handled serum samples analyzed within 8 hours and kept at 22 degrees C.