Plasma Ionized Calcium Concentration Research Articles

Acid-base imbalances and the association of blood-gas variables, electrolytes, and biochemical analytes with outcome in hospitalized calves undergoing abdominal surgery.

Surgical abdominal emergencies in calves are associated with a guarded prognosis and have the potential for complex metabolic derangements including acid-base imbalances. To perform a comprehensive analysis of acid-base status and to assess the prognostic relevance of preoperative clinicopathologic variables in calves undergoing abdominal surgery. Hospital-based study samples of 535 (dataset 1; DS1) and 83 calves (dataset 2; DS2). Retrospective (DS1) and prospective (DS2) case series. In DS1, acidemia (pH <7.33) was present in 49.9%, whereas alkalemia (pH >7.37) was present in 30.7% of calves. Plasma L-lactate, chloride, and serum inorganic phosphorus concentration accounted for 51.9%, 11.6% and 9.4% of the variation of venous blood pH, respectively. Classification tree analysis indicated that a negative outcome (death or euthanasia during hospitalization) was associated with venous pO2 ≤33.6 mm Hg, anion gap >18.3 and >22.9mEq/L, serum albumin concentration ≤36.5 and ≤29.4g/L, serum urea concentration >4.4 mmol/L, and plasma ionized calcium concentration ≤1.26 mmol/L. The area under the receiver operating characteristic curve of this model was 0.85 (95% CI: 0.82-0.89, P < .001) and the resulting sensitivity and specificity for the prediction of nonsurvival at the optimal probability cut-point of 0.5 was 89.8% and 65.7%, respectively. In DS2 the model had a similar sensitivity and specificity of 90.5% and 70%, respectively. Clinicopathologic imbalances and associated changes of acid-base status are common in calves with surgical abdominal emergencies and have clinical utility for the prediction of a negative postoperative outcome.

Negative calcium balance despite normal plasma ionized calcium concentrations during citrate anticoagulated continuous venovenous hemofiltration (CVVH) in ICU patients

BackgroundSupplementation of calcium during continuous venovenous hemofiltration (CVVH) with citrate anticoagulation is usually titrated using a target blood ionized calcium concentration. Plasma calcium concentrations may be normal despite substantial calcium loss, by mobilization of calcium from the skeleton. Aim of our study is to develop an equation to calculate CVVH calcium and to retrospectively calculate CVVH calcium balance in a cohort of ICU-patients.MethodsThis is a single-center retrospective observational cohort study. In a subcohort of patients, all calcium excretion measurements in patients treated with citrate CVVH were randomly divided into a development set (n = 324 in 42 patients) and a validation set (n = 441 in 42 different patients). Using mixed linear models, we developed an equation to calculate calcium excretion from routinely available parameters. We retrospectively calculated calcium balance in 788 patients treated with citrate CVVH between 2014 and 2021.ResultsCalcium excretion (mmol/24 h) was − 1.2877 + 0.646*[Ca]blood,total * ultrafiltrate (l/24 h) + 0.107*blood flow (ml/h). The mean error of the estimation was − 1.0 ± 6.7 mmol/24 h, the mean absolute error was 4.8 ± 4.8 mmol/24 h. Calculated calcium excretion was 105.8 ± 19.3 mmol/24 h. Mean daily CVVH calcium balance was − 12.0 ± 20.0 mmol/24 h. Mean cumulative calcium balance ranged from − 3687 to 448 mmol.ConclusionDuring citrate CVVH, calcium balance was negative in most patients, despite supplementation of calcium based on plasma ionized calcium levels. This may contribute to demineralization of the skeleton. We propose that calcium supplementation should be based on both plasma ionized calcium and a simple calculation of calcium excretion by CVVH.Graphical abstract

Renal Contributions to Age-Related Changes in Mineral Metabolism.

ABSTRACTAging results in a general decline in function in most systems. This is particularly true with respect to the skeleton and renal systems, impacting mineral homeostasis. Calcium and phosphate regulation requires tight coordination among the intestine, bone, parathyroid gland, and kidney. The role of the intestine is to absorb calcium and phosphate from the diet. The bone stores or releases calcium and phosphate depending on the body's needs. In response to low plasma ionized calcium concentration, the parathyroid gland produces parathyroid hormone, which modulates bone turnover. The kidney reabsorbs or excretes the minerals and serves as the final regulator of plasma concentration. Many hormones are involved in this process in addition to parathyroid hormone, including fibroblast growth factor 23 produced by the bone and calcitriol synthesized by the kidney. Sclerostin, calcitonin, osteoprotegerin, and receptor activator of nuclear factor‐κB ligand also contribute to tissue‐specific regulation. Changes in the function of organs due to aging or disease can perturb this balance. During aging, the intestine cannot absorb calcium efficiently due to decreased expression of key proteins. In the bone, the balance between bone formation and bone resorption tends toward the latter in older individuals. The kidney may not filter blood as efficiently in the later decades of life, and the expression of certain proteins necessary for mineral homeostasis declines with age. These changes often lead to dysregulation of organismal mineral homeostasis. This review will focus on how mineral homeostasis is impacted by aging with a particular emphasis on the kidney's role in this process. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on electrolyte and acid-base variables in dogs with suspected intracranial hypertension.

BackgroundHyperosmolar agents frequently are used to decrease intracranial pressure but their effects on electrolyte and acid‐base variables have not been prospectively investigated.ObjectivesCompare duration and magnitude of changes in electrolyte and acid‐base variables after hyperosmolar treatment.AnimalsTwenty‐eight client‐owned dogs with intracranial hypertension caused by various pathologies.MethodsProspective, randomized, nonblinded, experimental cohort study. Fifteen dogs received a single dose (4 mL/kg) of 7.2% hypertonic saline (HTS), 13 dogs received 20% mannitol (MAN) 1 g/kg IV. Electrolyte and acid‐base variables were measured before (T0), and 5 (T5), 60 (T60), and 120 (T120) minutes after administration. Variables were compared between treatments and among time points within treatment groups.ResultsMean plasma sodium and chloride concentrations were higher after HTS than MAN at T5 (158 vs 141 mEq/L; 126 vs 109 mEq/L) and significant differences were maintained at all time points. After HTS, plasma sodium and chloride concentrations remained increased from T0 at all time points. After MAN, plasma sodium and chloride concentrations decreased at T5, but these changes were not maintained at T60 and T120. Plasma potassium concentration was lower at T5 after HTS compared with T0 (3.6 vs 3.9 mEq/L) and compared to MAN (3.6 vs 4.1 mEq/L). At T60 and T120, plasma ionized calcium concentration was lower after HTS than MAN (1.2 vs 1.3 mmol/L). No significant differences were found in acid‐base variables between treatments.Conclusions and Clinical ImportanceAt the administered dose, dogs receiving HTS showed sustained increases in plasma sodium and chloride concentrations, whereas dogs receiving MAN showed transient decreases. Future studies should assess the effects of multiple doses of hyperosmolar agents on electrolyte and acid‐base variables.

Optimization of infusional calcium gluconate for prevention of hypocalcemic reactions during therapeutic plasma exchange.

We sought to optimize direct intravenous infusion of calcium gluconate (CaGlu) for maintaining plasma ionized calcium concentration ([Ca2+ ]) and preventing hypocalcemic reactions during 34 consecutive 1-volume therapeutic plasma exchanges (TPEs) in eight patients. CaGlu, 2 g in 50 mL of 0.9% NaCl, was prepared by our hospital pharmacy and infused at either 1.0 or 1.6 g/h during alternate TPE. Plasma [Ca2+ ] was monitored at intervals of 20 to 30 minutes. At 1 g/h of CaGlu, plasma [Ca2+ ] fell by 8.35% after 40 to 50 minutes and then plateaued. At 1.6 g/h of CaGlu, plasma [Ca2+ ] fell by 6% after 20 to 30 minutes and then plateaued. The difference at 40 to 50 minutes was significant (P = .015). Hypocalcemic reactions were noted in three patients during 5 of 17 TPE at 1.0 g/h (all after 40 to 60 minutes) but 0 of 17 TPE at 1.6 g/h (P = .044). CaGlu at 1.6 g/h stabilized plasma [Ca2+ ] and appears to prevent hypocalcemic reactions during TPE.

Effects of pH and the plasma or serum concentrations of total calcium, chloride, magnesium, l-lactate, and albumin on the plasma ionized calcium concentration in calves.

BackgroundThe plasma ionized calcium concentration (cCa2+) represents the biologically active form of calcium and is the preferred method for evaluating calcium status in animals. Different pH‐corrective equations have been developed for human plasma, but the validity of the equations for bovine plasma is unknown.HypothesisWe hypothesized that pH‐corrective equations for bovine plasma would be similar to those used for human plasma; cCa2+ was dependent on the plasma concentrations of total calcium (cTCa), chloride (cCl), L‐lactate (cLactate), and albumin (cAlbumin); and the in vitro and in vivo cCa2+‐pH relationships would differ.AnimalsTen healthy calves (in vitro study), 1426 critically ill calves.MethodsThe in vitro plasma log10(cCa2+)‐pH relationship was determined by CO2 tonometry of 465 plasma samples. Plasma cCl was altered by equivolume dilution of plasma with 3 electrolyte solutions of different cCl. The in vivo plasma cCa2+‐pH relationship was investigated and validated using clinicopathologic data extracted from the medical records of 950 (model development) and 476 (model validation) critically ill calves.ResultspH‐corrective equations for bovine plasma were similar to those used for human plasma. Plasma cCa2+ increased in vitro with increases in plasma cCl. Plasma cCa2+ in critically ill calves was associated with plasma cTCa, blood pH, plasma cCl, serum cMg, and cL‐lactate (R 2 = 0.69) but not plasma cAlbumin.Conclusions and Clinical ImportanceCalculation of cCa2+ from cTCa in calf plasma or serum requires adjustment for at least pH and cCl when 1 or both are outside the reference range.

Parathyroid immunohistochemistry in a 12-year-old mixed-breed dog with parathyroid adenocarcinoma

SummaryA 12-year-old, female, spayed, mixed-breed dog with acute lethargy, anorexia and weakness and markedly elevated total and ionised calcium concentration showed an enlarged left cranial parathyroid gland on ultrasonography of...

A new prescription model for regional citrate anticoagulation in therapeutic plasma exchanges

BackgroundRegional citrate anticoagulation (RCA) is proposed for various extracorporeal purification techniques to overcome the risk of bleeding that might result from systemic anticoagulation. Yet, no individualized treatment protocol has been proposed for therapeutic plasma exchange (TPE) so far. The objective of this study was to assess the determinants of blood citrate concentration needed and to develop an individualized RCA protocol useful for clinical practice.MethodsThe study population included 14 patients who underwent a total of 47 TPE sessions. Citrate was infused pre-plasmafilter. Post-plasmafilter and systemic plasma ionized calcium concentrations were measured at standardized time intervals. An algorithm was proposed for the supplementation of calcium. During the discovery phase, citrate was infused at a fixed starting rate, and adapted accordingly to obtained post-plasmafilter ionized calcium levels. Using a mathematical approach, an algorithm was thereafter developed for individualized prescriptions of citrate.ResultsPre-treatment values of hematocrit and plasma ionized calcium were the main determinants of the required rate of citrate infusion. These can be integrated into a final equation enabling to individualize the prescription. A prefilter ionized calcium concentration between 0.24 and 0.33 mmol/l prevented coagulation of the extracorporeal circuit. Significant hypocalcemia occurred in 8.5% of treatments. There were no significant acid–base disturbances.ConclusionWe propose a new protocol, which enables for the first time to individualize the prescription of regional citrate anticoagulation during TPE, in an efficient manner. The immediately obtained regional anticoagulation protects against both the risk of coagulation of the membrane and the exposure to an excess of citrate.

Stability of citrate and calcium dosing in citrate renal replacement therapy

Citrate is the recommended anticoagulant for continuous renal replacement therapy (RRT)[1], and is thought to confer numerous benefits, including more continuous hours of filtration, fewer total circuits used, less overall cost and maybe improved patient and kidney survival when compared with heparin anticoagulation[2]. Citrate is run pre filter, calcium is infused post filter, the rates of both determined by the filter and patient ionised calcium level respectively. This is monitored by blood tests, which must be sampled frequently. Filter and patient ionised calcium levels, citrate and calcium infusion rates, are recorded as part of clinical practice at RSCH. The target plasma ionised calcium concentration is 1.0 - 1.2mM, the target filter ionised calcium concentration is 0.25 - 0.5mM.

Preliminary validation of assays to measure parameters of calcium metabolism in captive Asian and African elephants in western Europe

Hypocalcemia is a well known cause of dystocia in animals, including elephants in captivity. In order to study calcium metabolism in elephants, it is of utmost importance to use properly validated assays, as these might be prone to specific matrix effects in elephant blood. The aim of the current study was to conduct preliminary work for validation of various parameters involved in calcium metabolism in both blood and urine of captive elephants. Basal values of these parameters were compared between Asian elephants (Elephas maximus) and African elephants (Loxodonta africana). Preliminary testing of total calcium, inorganic phosphorus, and creatinine appeared valid for use in plasma and creatinine in urine in both species. Furthermore, measurements of bone alkaline phosphatase and N-terminal telopeptide of type I collagen appeared valid for use in Asian elephants. Mean heparinized plasma ionized calcium concentration and pH were not significantly affected by 3 cycles of freezing and thawing. Storage at 4 °C, room temperature, and 37 °C for 6, 12, and 24 hr did not alter the heparinized plasma ionized calcium concentration in Asian elephants. The following linear regression equation using pH (range: 6.858-7.887) and ionized calcium concentration in heparinized plasma was utilized: iCa(7.4) (mmol/l) = -2.1075 + 0.3130·pH(actual) + 0.8296·iCa(actual) (mmol/l). Mean basal values for pH and plasma in Asian elephant whole blood were 7.40 ± 0.048 and 7.49 ± 0.077, respectively. The urinary specific gravity and creatinine concentrations in both Asian and African elephants were significantly correlated and both were significantly lower in Asian elephants.

Is plasma calcium concentration implicated in the development of critical illness polyneuropathy and myopathy?

IntroductionThis prospective study investigated whether plasma ionized calcium concentration abnormalities and other electrolyte disturbances represent risk factors for the development of critical illness polyneuromyopathy (CIPNM) in ICU patients.MethodsOne hundred and ninety consecutive adult critically ill patients with prolonged ICU stay (longer than 7 days) were prospectively evaluated. Patients with acute weakness and/or weaning difficulties were subjected to extensive electrophysiological measurements in order to establish the diagnosis of CIPNM. All recognized and/or possible risk factors for development of CIPNM were recorded.ResultsThe diagnosis of CIPNM was confirmed in 40 patients (21.05%). By applying a logistic regression model, hypocalcemia (P = 0.02), hypercalcemia (P = 0.01) and septic shock (P = 0.04) were independently associated with the development of CIPNM in critically ill patients.ConclusionsWe found that septic shock and abnormal fluctuations of plasma Ca2+ concentration represent significant risk factors for the development of CIPNM in critically ill patients.

A mathematical model of parathyroid hormone response to acute changes in plasma ionized calcium concentration in humans

A complex bio-mechanism, commonly referred to as calcium homeostasis, regulates plasma ionized calcium (Ca 2+) concentration in the human body within a narrow range which is crucial for maintaining normal physiology and metabolism. Taking a step towards creating a complete mathematical model of calcium homeostasis, we focus on the short-term dynamics of calcium homeostasis and consider the response of the parathyroid glands to acute changes in plasma Ca 2+ concentration. We review available models, discuss their limitations, then present a two-pool, linear, time-varying model to describe the dynamics of this calcium homeostasis subsystem, the Ca–PTH axis. We propose that plasma PTH concentration and plasma Ca 2+ concentration bear an asymmetric reverse sigmoid relation. The parameters of our model are successfully estimated based on clinical data corresponding to three healthy subjects that have undergone induced hypocalcemic clamp tests. In the first validation of this kind, with parameters estimated separately for each subject we test the model’s ability to predict the same subject’s induced hypercalcemic clamp test responses. Our results demonstrate that a two-pool, linear, time-varying model with an asymmetric reverse sigmoid relation characterizes the short-term dynamics of the Ca–PTH axis.

Effect of altrenogest‐treatment of mares in late gestation on adrenocortical function, blood count and plasma electrolytes in their foals

Mares with compromised pregnancies are often treated with altrenogest to prevent abortion. However, there is only limited information about effects on the foal when altrenogest treatment is continued during final maturation of the fetus. To determine effects of altrenogest treatment during late gestation in mares on maturity, haematology changes, adrenocortical function and serum electrolytes in their newborn foals. Six mares were treated with altrenogest (0.088 mg/kg bwt) once daily from Day 280 of pregnancy until foaling and 7 mares served as controls. Foals born to altrenogest-treated mares had a significantly lower neutrophil/lymphocyte ratio on the first day after birth than control foals (P<0.05). Basal plasma cortisol concentrations immediately after birth were higher in foals of altrenogest-treated mares than in control foals (P<0.05). Cortisol release in response to exogenous adrenocorticotropic hormone (ACTH)--except for higher values 15 min after ACTH injection in foals of altrenogest-treated mares on Day 1--revealed no differences in adrenocortical function between the groups of foals. Plasma potassium concentration in foals from altrenogest-treated mares compared to control foals was significantly lower immediately after birth (P<0.05) and plasma ionised calcium concentration was significantly lower 3 h after birth (P = 0.01). Altrenogest treatment of pregnant mares prolonged labour had no major effects on adrenocortical function in foals. A reduced neutrophil/lymphocyte ratio in these foals may suggest either immunomodulatory effects of altrenogest or dysmaturity of the foals.

Effects of intravenous administration of two volumes of calcium solution on plasma ionized calcium concentration and recovery from naturally occurring hypocalcemia in lactating dairy cows

To compare the effects of administration of 2 volumes of a calcium solution (calcium oxide and calcium gluconate) on plasma ionized calcium concentration (PICaC) and clinical recovery from naturally occurring hypocalcemia (NOHC; milk fever) in lactating dairy cows. 123 cows with NOHC (PICaC < 0.95 mmol/L [3.81 mg/dL]) and 20 clinically normal control cows. Affected cows were treated IV once or repeatedly with 450 (n = 56) or 750 mL (67) of calcium solution (1.65 g of calcium/100 mL) until clinical recovery was achieved. The PICaC was assessed 48 hours after the first treatment or after the treatment that achieved clinical recovery. Biochemical recovery was defined as PICaC > or = 0.95 mmol/L. Plasma from control cows was used for PICaC reference range determination. Plasma samples from both groups were assessed after storage for 20 days at 20 degrees C. The PICaC reference range derived from blood collected in tubes containing lithium heparin was 1.02 to 1.29 mmol/L (4.09 to 5.17 mg/dL). Following storage, plasma samples were suitable for PICaC assessment. All cows treated with > or = 1 volume of 450 and 750 mL of calcium solution recovered clinically; however, 31 of 83 (37%) evaluated cows were not biochemically recovered at 48 hours following treatment. Only cows with PICaC < 0.48 mmol/L (1.92 mg/dL) before the first treatment had to be treated > or = 3 times. Results did not support the need to increase the administered volume of calcium solution from 450 to 750 mL for treatment of NOHC in dairy cows.

Effects of intravenous administration of two volumes of calcium solution on plasma ionized calcium concentration and recovery from naturally occurring hypocalcemia in lactating dairy cows

Effects of intravenous administration of two volumes of calcium solution on plasma ionized calcium concentration and recovery from naturally occurring hypocalcemia in lactating dairy cows

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

ObjectiveTo demonstrate the effect of anesthesia and surgery on serum ionized magnesium and ionized calcium concentrations in clinical canine and feline patients. Animals37 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 methodsPlasma ionized and serum total magnesium, and plasma ionized calcium were measured prior to and after a group-standardized anesthetic protocol. ResultsRegardless 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 relevanceA 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.

Dose-response relationship between plasma ionized calcium concentration and thrombelastography

Objectives: To establish the threshold value for calcium at which coagulation commenced and to investigate the range over which changes in ionized calcium influenced coagulation. Design: Controlled, nonblinded, in vitro observational study. Setting: The study was conducted in a university-based laboratory. Participants: Blood was obtained from healthy volunteers. Interventions: One hundred samples of citrated blood were recalcified using varying quantities of 10% calcium chloride solution. Heparinized samples from the recalcified blood were obtained for measurement of ionized calcium concentration (Ca 2+). Measurements and results: Coagulation of the recalcified samples was analyzed using thrombelastography. The ionized calcium concentration in recalcified blood was measured using a calcium electrode in a blood gas analyzer. No sample with a Ca 2+ < 0.33 mmol/L showed any clot formation. Normal coagulation measures were obtained in almost all samples in which the Ca 2+ was >0.56 mmol/L. Final clot strength appeared to be independent of Ca 2+ once the threshold value of 0.33 mmol/L was exceeded. Conclusions: Ca 2+ of <0.33 mmol/L is necessary to prevent coagulation. Ca 2+ > 0.56 is unlikely to be the cause of coagulation abnormalities during surgical procedures in which calcium metabolism is deranged. Between these values, Ca 2+ may exert an effect on the rate of clot formation, but final clot strength should be unaffected.

Incidence and prognostic value of low plasma ionized calcium concentration in cats with acute pancreatitis: 46 cases (1996-1998).

To determine the incidence and prognostic significance of low plasma ionized calcium concentration in cats with clinical signs of acute pancreatitis (AP). Retrospective study. 46 cats with AP and 92 control cats with nonpancreatic diseases. Medical records were reviewed, and results of clinicopathologic testing, including plasma ionized and total calcium concentrations, acid-base values, and electrolyte concentrations, were recorded. Cats with AP were grouped on the basis of outcome (survived vs died or were euthanatized), and plasma ionized calcium concentrations, acid-base values, and electrolyte concentrations were compared between groups. Serum total calcium concentration was low in 19 (41%) cats with AP, and plasma ionized calcium concentration was low in 28 (61%). Cats with AP had a significantly lower median plasma ionized calcium concentration (1.07 mmol/L) than did control cats (1.12 mmol/L). Nineteen (41%) cats with AP died or were euthanatized; these cats had a significantly lower median plasma ionized calcium concentration (1.00 mmol/L) than did cats that survived (1.12 mmol/L). Ten of the 13 cats with AP that had plasma ionized calcium concentrations < or = 1.00 mmol/L died or were euthanatized. Results suggest that low plasma ionized calcium concentration is common in cats with AP and is associated with a poorer outcome. A grave prognosis and aggressive medical treatment are warranted for cats with AP that have a plasma ionized calcium concentration < or = 1.00 mmol/L.

Hypertonic sodium bicarbonate is effective in the acute management of verapamil toxicity in a swine model

Study Objective: This study was conducted to determine whether hypertonic sodium bicarbonate would improve the hypotension associated with severe verapamil toxicity compared with volume expansion. Methods: The study design used a nonblinded acute animal preparation. Twenty-four anesthetized and instrumented swine were poisoned with verapamil delivered at a rate of 1 mg/kg per hour for 10 minutes followed by incremental increases of 1 mg/kg per hour every 10 minutes until the endpoint of a mean arterial blood pressure of 45% of baseline was achieved. Animals alternately received either 4 mEq/kg of hypertonic sodium bicarbonate intravenously over 4 minutes or similar volumes of 0.6% sodium chloride in 10% mannitol (control). The main outcome parameter followed was mean arterial pressure. In addition, physiologic parameters including cardiac output, heart rate, pH, PCO2, PO2, plasma ionized calcium, sodium, and potassium were monitored. Results: Verapamil toxicity, as defined by a mean arterial pressure of 45% of baseline, was produced in all animals following an average verapamil infusion dose of 0.6±0.12 mg/kg. This dose produced an average plasma verapamil concentration of 728.1±155.4 μg/L, with no significant difference between groups. Swine treated with hypertonic sodium bicarbonate experienced a significant increase in mean arterial pressure (>50%) and cardiac output (>30%) over the first 20 minutes that slowly equilibrated with the control group over the remainder of the experiment. As expected, plasma sodium concentrations were elevated significantly in the sodium bicarbonate group while plasma potassium concentrations were decreased significantly. Finally, there was a significant decrease in plasma ionized calcium concentration in the sodium bicarbonate–treated group compared with controls. Conclusion: Hypertonic sodium bicarbonate reversed the hypotension and cardiac output depression of severe verapamil toxicity in a swine model. [Tanen DA, Ruha A-M, Curry SC, Graeme KA, Reagan CG. Hypertonic sodium bicarbonate is effective in the acute management of verapamil toxicity in a swine model. Ann Emerg Med. December 2000;36:547-553.]

Eclampsia in dogs: 31 cases (1995–1998)

To compare clinical characteristics and laboratory findings of dogs with eclampsia with those of dogs without eclampsia. Retrospective study. 31 dogs with eclampsia (affected) and 31 with dystocia (controls). Information on signalment, type of diet, reproductive history, litter size, time from whelping to eclampsia, body weight, clinical signs, results of physical examination and hematologic and biochemical analyses, response to calcium supplementation, and recurrence was obtained from the medical records of all dogs with eclampsia evaluated between 1995 and 1998 and compared with information from medical records of 31 of 102 dogs with dystocia evaluated during the same period. Dogs with eclampsia weighed less, had a smaller body weight-to-litter size ratio, higher rectal temperature and heart and respiratory rates, and lower plasma total solids concentration than control dogs. Ionized calcium concentration was < or = 0.8 mmol/L for all but 1 of the affected dogs; median concentration for the affected dogs was significantly less than that for control dogs. Six (19%) dogs did not manifest typical clinical signs associated with eclampsia. Twelve (39%) dogs with eclampsia had previous litters; none had a history of eclampsia. Affected dogs were discharged from the hospital within hours after admission, but 3 dogs returned 1 to 3 weeks later because of recurrence of eclampsia. Eclampsia develops primarily in small-breed dogs with large litters. Plasma ionized calcium concentrations > 0.8 mmol/L in dogs with clinical signs typical of hypocalcemia may indicate that other causes of clinical signs should be considered. In addition, some dogs with eclampsia may have low ionized calcium concentrations and not manifest typical clinical signs.