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

Hypocalcemia in the Immediate Postoperative Period Following Metabolic Bariatric Surgery - Hype or Harm?

PURPOSE

Hypocalcemia post-metabolic bariatric surgery (MBS) is a known long-term complication after hypoabsorptive procedures. However, data on immediate postoperative calcium are limited. Our aim was to evaluate the prevalence of hypocalcemia on the 1st postoperative day after MBS and correlate it with potential associated factors.

MATERIALS AND METHODS

We analyzed data from all consecutive index MBS over 1 year. We collected data on demographics and on preoperative and postoperative values of serum calcium (TC), albumin, adjusted calcium (AC-Payne formula), magnesium, phosphorus, preoperative vitamin-D, and postoperative 24-h urine output, intravenous fluids (IVF), bolus intravenous furosemide, and creatine phosphokinase (CPK). Continuous data are expressed as means ± SD (range). Categorical data are presented as frequencies (%). Linear regression was implemented to designate potential correlations.

RESULTS

The cohort included 86 patients (58.1% females). The mean preoperative TC was 9.4mg/dL ± 0.4 (8.5-10.5) and mean postoperative TC 7.8mg/dL ± 0.6 (6.3-9.3, 17.0% decrease). The mean preoperative AC was 10.1mg/dL ± 0.4 (9.2-11.2) and mean postoperative AC 8.5mg/dL ± 0.6 (7.0-10.0, 15.8% decrease). Seventy-three patients (84.8%) had abnormally low TC (< 8.5mg/dL), and 43 (50%) abnormally low AC. There was only weak correlation between postoperative TC and AC with magnesium (r = 0.258), phosphorus (r = 0.269), vitamin-D (-0.163), 24-h urine output (r = -0.168), IVF (r = -0.237), bolus furosemide (r = 0.155), and mean operative time (r = 0.010).

CONCLUSIONS

In our cohort of patients, hypocalcemia was a real problem but we did not find any significant correlation with the examined factors. Further studies are warranted to validate our findings and investigate other potential correlations.

Total serum and ionized magnesium concentrations in healthy and hospitalized dogs

OBJECTIVE

To determine if an association between ionized magnesium (iMg) and total magnesium (tMg) exists in healthy and hospitalized dogs admitted through an emergency service and to assess the associations between iMg and tMg with total protein, albumin, ionized calcium, and total calcium.

DESIGN

Prospective cohort study.

SETTING

Veterinary teaching hospital.

ANIMALS

Sixty-nine dogs were enrolled. The healthy control group (group 1) included 24 dogs, and the hospitalized group (group 2) included 45 dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For both groups, signalment, a venous blood gas, and serum biochemistry were obtained. In addition, the presumptive diagnosis was recorded for group 2. Blood was obtained prior to any therapeutic interventions. Group 1 tMg was within the reference interval (RI), and the values for iMg were used to provide a healthy group range (HGR) of 0.44-0.50 mmol/L. Group 2 tMg was within the RI, but iMg was below the calculated HGR range (group 2 median iMg = 0.4 mmol/L; range = 0.27-0.70). There was a significant positive correlation between iMg and tMg in each group (group 1: r = 0.6713, P = 0.0003; group 2: r = 0.5312, P = 0.0002). Ionized Mg and tMg were not significantly associated with any of the other evaluated variables in either group.

CONCLUSIONS

Ionized Mg and tMg were significantly associated in both healthy and hospitalized dogs, but the relationship was weaker in the hospitalized dogs compared with the healthy population. For hospitalized dogs, the relationship was weak enough to question the validity of using iMg and tMg interchangeably to track magnesium status.

The Effect of Different Opioids on Acid-Base Balance and Blood Gas Analysis in Hospitalized Dogs

Pain management is central to veterinary practice, contributing to successful case outcomes and enhancement of the veterinarian-client-patient relationship. Analgesic drugs represent one of the pillars of the multimodal approach to acute and chronic pain management. In dogs, the most used opioids are methadone, buprenorphine and tramadol. Several episodes of hypoglycemia in people treated with tramadol and methadone have recently been described. The aim of this work is to evaluate the changes in the glycemic and acid-base balance induced by tramadol, methadone and buprenorphine in hospitalized dogs. A retrospective review of the medical records of dogs hospitalized for both medical and surgical reasons was performed. During 2018-2020, a total of 876 canine patients were treated with opioids, including 228 with tramadol, 273 with methadone and 375 with buprenorphine. Of all these dogs, only a small percentage met the inclusion criteria presented in the initial design. All the hospitalized animals were monitored daily through clinical examination and blood sampling. Blood samples were obtained before opioid administration (T0), and 24 h (T1) and 48 h (T2) after °pioid administration. The following parameters were evaluated: blood gas value (pH, pCO₂), acid-base state (cHCO₃), oxymetric values (ctHb, haematocrit), electrolyte values (K+, Na+, iCa, Cl-) and metabolic values (glucose, lactate, anion GAP K+c). The glycemic value in enrolled dogs showed a decrease over time, regardless of the type of opioid used, but remained within the physiological range. The highest average glycemic drop was recorded for methadone, between T0 and T1, followed by tramadol between T1 and T2, while buprenorphine recorded the highest overall glycemic drop between T0-T2 when compared to the other two opioids. Female dogs showed the greatest drop in glycemic value. Lactate concentration always presented values beyond the physiological range at an early stage, which then normalized quickly. Measurement of electrolyte concentrations showed a consistent increase in the values of iCa, Na and Cl. In hospitalized dogs treated with opioids monitoring of gas analytic parameters is important and more attention should be paid to patients hospitalized with certain metabolic and endocrine diseases.

Comparison of acid-base and electrolyte changes following administration of 6% hydroxyethyl starch 130/0.42 in a saline and a polyionic solution in anaesthetized dogs

OBJECTIVE

To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) in either a buffered, electrolyte-balanced (HES-BAL) or saline (HES-SAL) carrier solution on electrolyte concentrations and acid-base parameters in healthy anaesthetized dogs.

STUDY DESIGN

Prospective randomised clinical study.

ANIMALS

A group of 40 client-owned dogs undergoing general anaesthesia for elective surgical procedures or diagnostic imaging.

METHODS

During anaesthesia, dogs were intravenously administered 15 mL kg^-1 of either HES-SAL (n = 20) or HES-BAL (n = 20) over 30-40 minutes. Jugular blood samples were analysed before (T₀) and 5 minutes (T₅), 1 hour (T₆₀) and 3 hours (T₁₈₀) after fluid administration. Sodium, potassium, chloride, ionised calcium, phosphate, albumin, pH, venous pCO₂, base excess (BE), bicarbonate and anion gap were determined and strong ion difference (SID) and total quantity of weak nonvolatile acids were calculated for each time point.

RESULTS

Chloride was significantly increased at T₅, T₆₀ and T₁₈₀ compared with T₀ after HES-SAL, and was significantly greater after HES-SAL than after HES-BAL at T₅ (p = 0.042). Ionised calcium was significantly decreased at T₅ compared with T₀ after HES-SAL, and was significantly lower after HES-SAL than after HES-BAL at T₅ (p < 0.001). Bicarbonate was significantly lower after HES-SAL than after HES-BAL at T₅ (p = 0.004) and T₆₀ (p = 0.032). BE was significantly lower after HES-SAL than after HES-BAL at T₅ (p < 0.001) and T₆₀ (p = 0.007). SID was significantly decreased after HES-SAL at T₅ and T₆₀ compared with T₀, and was significantly lower after HES-SAL than after HES-BAL at T₅ (p = 0.027). Mean electrolyte and acid-base parameters remained within or marginally outside of reference intervals.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in both groups were minor and short-lived with either fluid in healthy individuals, but might become clinically relevant with higher fluid doses or in critically ill dogs.

General Anesthesia Effect on Acid Base and Serum Calcium and Phosphorus Levels in Relation to Anesthetic Risk in Dogs

The aim of this study was to investigate the influence of general anesthesia on selected blood parameters in 53 surgical patients belonging to five ASA groups. The venous blood pH during the preoperative period was under physiological values only in the ASA V group of dogs. The lowest average values of pH levels were found in all ASA groups during the 30th minute of the surgical procedure. The pre-operative measurements revealed the average concentration of calcium in the blood serum below the physiological range in the groups with higher anesthetic risk, ASA III, IV and V. Most dogs with hypocalcemia during the whole monitored period were in the ASA III group (69.2%). After premedication and sedation a decrease in the concentration of calcium in all groups was observed, except for the ASA IV group. Changes in the concentration of calcium were significant in the ASA II group (P ≤ 0.01). Between the groups, there were no significant differences reported in calcium concentrations during the monitored period. The lowest average value of phosphorus concentration was recorded in the ASA III group and the highest in the ASA V group. In the postoperative period the increase in phosphorus concentrations was observed in all groups except ASA III. Acidaemia, hypocalcaemia and hyperphosphatemia may present a potential risk mostly in endangered animals, so additional monitoring of these parameters, along with commonly used anesthetic monitoring, is essential and might be significantly helpful.

Cardiopulmonary effects of thiopental versus propofol as an induction agent prior to isoflurane anesthesia in chair trained rhesus macaques (Macaca mulatta)

The purpose of this study was to evaluate the effects of thiopental versus propofol on cardiopulmonary functions, when used as an induction agent prior to isoflurane anesthesia in rhesus monkeys. Eight healthy rhesus monkeys weighing 3.72 to 5.7 kg, 4-5 years old, were used in the study. Anesthesia was induced with thiopental or propofol intravenous injection, and then maintained with isoflurane in oxygen for 45 minutes. Cardiopulmonary measurements were obtained before and 5, 15, 30, 45, and 60 minutes after induction. The induction doses of thiopental and propofol were 19.41±0.54 and 9.33±1.02 mg/kg, respectively. In both groups, the values of heart rate, respiratory rate, temperature, systolic blood pressure, mean blood pressure, diastolic blood pressure, pH, and lactate were decreased, while the values of partial pressure of carbon dioxide, partial pressure of oxygen, total carbon dioxide, bicarbonate, oxygen saturation, and base excess in the extracellular fluid were increased, as compared with baseline. Systolic blood pressure was significantly lower in thiopental group compare to propofol group. Induction time was very short in both agents but not revealed a significant difference between both groups. However, recovery time was extremely faster in the propofol group. Our results demonstrated that propofol provides a minor suppression in systolic arterial blood pressure than thiopental sodium. In addition, propofol have a fast recovery effect from the anesthesia as well. Furthermore, it is suggested that thiopental sodium could also be used to induce anesthesia instead of propofol, despite slight more suppression of cardiopulmonary function compared to thiopental sodium.

Ionized calcium concentrations in cats with septic peritonitis: 55 cases (1990-2008)

OBJECTIVE

To report the prevalence of ionized hypocalcemia (iHCa) in cats with septic peritonitis, and to determine whether hypocalcemic cats had increased morbidity and mortality when compared with normocalcemic cats.

DESIGN

Retrospective clinical study.

SETTING

University teaching hospital.

ANIMALS

Fifty-five client-owned cats with septic peritonitis.

MEASUREMENTS

Medical records of 55 cats with confirmed septic peritonitis meeting the study inclusion criteria were reviewed. Information obtained included signalment, cause of peritonitis, length of hospitalization (LOH), length of ICU stay, and outcome. Results from serum biochemical analysis, blood gas analysis, and coagulation testing from the time of diagnosis, and all ionized calcium (iCa) measurements during hospitalization were recorded. Systolic blood pressure, the presence of arrhythmias and administration of vasopressor agents, blood products, and sodium bicarbonate were documented. iCa concentration at the time of diagnosis and lowest recorded value during hospitalization were compared with LOH and length of ICU stay, survival to hospital discharge, and clinical and clinicopathologic data.

MAIN RESULTS

iHCa (iCa<1.20 mmol/L) was found in 89% of cats (49/55) at the time of diagnosis of septic peritonitis and 93% (51/55) at any time during hospitalization. There was no association between the presence or severity of iHCa at diagnosis and survival to hospital discharge. LOH (P=0.046) and duration of ICU stay (P=0.026) were significantly correlated with the lowest iCa recorded during hospitalization. Failure to normalize iCa during hospitalization was associated with a decreased survival rate to discharge (P=0.029) in patients with iHCa. iHCa was not associated with an increased prevalence of hypotension, coagulopathy, arrhythmias, or evaluated therapies.

CONCLUSIONS

iHCa is more prevalent in cats with septic peritonitis than described previously. Failure of iCa to normalize during hospitalization may be a negative prognostic indicator. iHCa may be predictive of a longer LOH and ICU stay, but is not necessarily associated with a poorer prognosis.

A comparison of total calcium, corrected calcium, and ionized calcium concentrations as indicators of calcium homeostasis among hypoalbuminemic dogs requiring intensive care

OBJECTIVE

(1) To evaluate whether total calcium (tCa) correlates with ionized calcium (iCa) in hypoalbuminemic dogs; (2) to evaluate whether calcium adjusted for albumin (Alb), or total protein (TP), or both accurately predict iCa concentrations and hence can be used to monitor calcium homeostasis in critically ill hypoalbuminemic dogs; and (3) to evaluate factors associated with any potential discrepancy in calcium classification between corrected total and ionized values.

DESIGN

Prospective observational clinical study.

SETTING

Small animal intensive care unit in a veterinary medical teaching hospital.

ANIMALS

Twenty-eight client-owned dogs with hypoalbuminemia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

iCa was determined using ion-specific electrode methodology, on heparinized plasma. The tCa concentration was adjusted for Alb and TP using published equations. In total 29% (8/28) of the hypoalbuminemic, critically ill dogs in this study were hypocalcemic at intensive care unit admission, as determined by iCa measurement. Corrected calcium values failed to accurately classify calcium status in 67.9% and 64.3% of cases, according to whether the Alb-adjusted or TP-adjusted values, respectively, were used. The sensitivity and specificity of the tCa to evaluate hypocalcemia was 100% and 47%, respectively. The sensitivity and specificity of the correction formulae were 37.5% and 79% for the Alb-adjusted values and 37.5% and 74% for TP-adjusted values. tCa overestimated the presence of hypocalcemia and underestimated the presence of normocalcemia, while corrected calcium values overestimated the presence of normocalcemia and underestimated the presence of hypocalcemia.

CONCLUSIONS

Calcium homeostasis in hypoalbuminemic critically ill dogs should be evaluated by iCa concentrations rather than tCa or calcium adjusted for Alb or TP. Given that tCa has 100% sensitivity for detecting hypocalcemia in this population it is recommended that all hypoalbuminemic and critically ill patients with low tCa should be evaluated with an iCa measurement.

Successful management of severe hypoventilation and hypercapnia in an alpaca (Vicugna pacos) with short-term mechanical ventilation

OBJECTIVE

To describe the successful management of an alpaca with severe hypoventilation and hypercapnia, suspected to be secondary to an anesthesia-related event.

CASE SUMMARY

A 3-year-old, female alpaca underwent a routine eye enucleation under general anesthesia after traumatic globe perforation. Severe hypoventilation and associated hypercapnia developed postoperatively resulting in a severe primary respiratory acidosis. The awake alpaca was supported with positive-pressure ventilation for approximately 20 hours before successful weaning. Recovery to hospital discharge occurred over the subsequent 5 days with the alpaca regaining apparently normal respiratory function.

NEW OR UNIQUE INFORMATION PROVIDED

To the knowledge of the authors, this is the first report describing positive-pressure ventilation of an alpaca in the veterinary literature. In this case of severe hypoventilation, ventilatory support was essential to the positive outcome. As South American camelids continue to increase in popularity there may be an increased demand for high-quality and sophisticated veterinary care for these animals. Mechanical ventilation can be used to help restore and maintain normal PO2, PCO2, and respiratory acid-base status in alpacas with ventilatory dysfunction.

Ionized hypercalcemia in dogs: a retrospective study of 109 cases (1998-2003)

BACKGROUND

Serum hypercalcemia in dogs has been reported in association with a variety of diseases. Serum-ionized calcium (iCa) concentration is a more accurate measure of hypercalcemia than total serum calcium or corrected serum calcium concentrations. The severity of hypercalcemia has been utilized to suggest the most likely differential diagnosis for the hypercalcemia.

HYPOTHESIS

Diseases causing ionized hypercalcemia may be different than those that cause increases in total or corrected serum calcium concentrations. The severity of ionized hypercalcemia in specific diseases cannot be used to determine the most likely differential diagnosis for ionized hypercalcemia.

ANIMALS

One-hundred and nine client-owned dogs with a definitive cause for their ionized hypercalcemia evaluated between 1998 and 2003 were included in this study.

METHODS

Retrospective, medical records review.

RESULTS

Neoplasia, specifically lymphosarcoma, followed by renal failure, hyperparathyroidism, and hypoadrenocorticism were the most common causes of ionized hypercalcemia. Dogs with lymphoma and anal sac adenocarcinoma have higher serum iCa concentrations than those with renal failure, hypoadrenocorticism, and other types of neoplasia. The magnitude of serum-ionized hypercalcemia did not predict specific disease states.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum-ionized hypercalcemia was most commonly associated with neoplasia, specifically lymphosarcoma. Although dogs with lymphosarcoma and anal sac adenocarcinoma had higher serum iCa concentrations than dogs with other diseases, the magnitude of the serum iCa concentration could not be used to predict the cause of hypercalcemia. Total serum calcium and corrected calcium concentrations did not accurately reflect the calcium status of the dogs in this study.

Ionized hypocalcemia in critically ill dogs

BACKGROUND

Ionized hypocalcemia (iHCa) is a common electrolyte disturbance in critically ill people, especially those with sepsis. The cause of the iHCa is not entirely understood and is likely multifactorial. Critically ill people with iHCa have longer hospital stays and higher mortality rates compared to people with normocalcemia. There are no published clinical studies evaluating the incidence and impact of iHCa in critically ill dogs.

HYPOTHESIS

iHCa occurs in critically ill dogs, is more prevalent in dogs with systemic inflammatory response syndrome (SIRS) or sepsis, and is associated with longer hospital stays and higher mortality.

ANIMALS

One hundred and forty-one client-owned dogs admitted to a companion animal intensive care unit (ICU) in a veterinary teaching hospital.

METHODS

Prospective observational study of sequentially enrolled dogs. Blood was collected and analyzed within an hour of admission from all dogs presented to the ICU that met study inclusion criteria.

RESULTS

The incidence of iHCa (iCa < 1.11 mmol/L) was 16%. The presence of iHCa was associated with longer ICU (P= .038) and hospital (P= .012) stays but not with decreased survival (P= .60). Dogs with sepsis as defined by >or=3 SIRS criteria and a positive culture were more likely to have iHCa (P= .050).

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs not previously treated with fluids or blood products intravenously, the finding of iHCa upon admission to the ICU predicted a longer duration of ICU and hospital stay. Septic dogs with positive cultures were more likely to have iHCa.