Use of Lactate in Small Animal Clinical Practice

Niveles séricos de la isoenzima creatina quinasa-MB y lactato deshidrogenasa como indicadores de daño miocárdico en perros con enfermedad valvular degenerativa

Se analizaron los niveles séricos de creatina quinasa-MB (CK-MB) y lactato deshidrogenasa (LDH) en 10 perros diagnosticados con enfermedad valvular degenerativa y en seis perros clínicamente sanos, con el objetivo de evaluar si sus niveles séricos indican daño miocárdico. Las muestras de suero se analizaron mediante el método UV. Se utilizó la prueba de diferenciación de medias para determinar diferencias entre medias, y la prueba de correlación de Pearson para determinar si existe correlación entre los niveles séricos de ambas enzimas. Los valores de CK-MB y de LDH fueron significativamente diferentes entre los dos grupos de pacientes. Los niveles de CK-MB y LDH tuvieron correlación positiva, pero no significativa.

Clinical use of plasma lactate concentration. Part 1: Physiology, pathophysiology, and measurement

OBJECTIVE

To review the current literature with respect to the physiology, pathophysiology, and measurement of lactate.

DATA SOURCES

Data were sourced from veterinary and human clinical trials, retrospective studies, experimental studies, and review articles. Articles were retrieved without date restrictions and were sourced primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Lactate is an important energy storage molecule, the production of which preserves cellular energy production and mitigates the acidosis from ATP hydrolysis. Although the most common cause of hyperlactatemia is inadequate tissue oxygen delivery, hyperlactatemia can, and does occur in the face of apparently adequate oxygen supply. At a cellular level, the pathogenesis of hyperlactatemia varies widely depending on the underlying cause. Microcirculatory dysfunction, mitochondrial dysfunction, and epinephrine-mediated stimulation of Na⁺ -K⁺ -ATPase pumps are likely important contributors to hyperlactatemia in critically ill patients. Ultimately, hyperlactatemia is a marker of altered cellular bioenergetics.

CONCLUSION

The etiology of hyperlactatemia is complex and multifactorial. Understanding the relevant pathophysiology is helpful when characterizing hyperlactatemia in clinical patients.

Assessment of a portable lactate meter for field use in the white rhinoceros (<i>Ceratotherium simum</i>)

Blood lactate is a predictor of mortality in critically ill humans and animals. Handheld lactate meters have the potential to be used in the field to evaluate the condition of severely injured rhinoceroses but have not been compared with laboratory-based methods. Agreement between a handheld lactate meter and a laboratory method was assessed, as was the stability of rhino blood lactate in the anticoagulant sodium fluoride/potassium oxalate (fluoride/oxalate). Blood samples were obtained from 53 white rhinos that had been immobilised for management reasons. Lactate was measured by means of a handheld meter using whole blood in heparin (WBHEP), whole blood in fluoride/oxalate (WBFO) and fluoride/oxalate plasma (PFO). Results were recorded in both blood (BL) and plasma (PL) modes and compared to an established laboratory method for measuring plasma lactate. To assess the stability of lactate over time, blood lactate in fluoride/oxalate was measured on the handheld meter at intervals for up to 91 h. Agreement was best using WBFO in PL mode, with small bias (−0.16), tight 95% limits of agreement (LOA) (−1.46, 1.14) and a Pc (95% CI) of 0.97 (0.92, 0.99). The agreement was improved for all sample types when using the PL mode compared to the blood lactate (BL) mode. Blood lactate was stable in fluoride/oxalate for 91 h, with a mean change from baseline of 0.15 (−0.178, 0.478) mmol/L (mean, 95% CI). The handheld meter was found to be suitable for field use in white rhinos but provided more reliable results with the device in PL mode. Furthermore, rhino blood lactate was found to be stable in fluoride/oxalate for as long as 3 days.

Time-dependent changes and prognostic value of lactatemia during the first 24 h of life in brachycephalic newborn dogs

Blood lactate concentration is known to be a good prognostic indicator associated with the severity of illness and the patient's outcome both in human and veterinary medicine. It also plays a significant role in the assessment of the newborn, being a good indicator of fetal hypoxia and the ideal predictor of morbidity at term in babies. In veterinary neonatal medicine, hyperlactatemia is considered a valid prognostic marker in critically ill foals; moreover, blood lactate measurement has been proposed for the evaluation of newborn viability and the assessment of fetal distress during delivery in dogs. Unfortunately, only a few studies have been published concerning the canine species. The present work examines 67 brachycephalic newborn dogs and their mothers, with the aim to evaluate the time-dependent changes of blood lactate and glucose concentration during the first 24 h after vaginal or caesarean delivery both in puppies and bitches. To our knowledge, this is the first published study examining the time-dependent changes of these parameters in the bitch after parturition. Within the studied population of puppies, non-surviving was significantly associated with a higher lactatemia and a lower APGAR score. Blood lactate was high at birth then progressively decreased during the first 24 h of life and a lack of normalization of blood lactate levels within this time interval was suggestive for a poor prognosis for the newborn dogs; moreover, the decrease appeared to be slower after vaginal delivery. Lactatemia also showed a positive correlation with glycemia at birth. Concerning the bitches examined, blood lactate was found to be significantly higher after vaginal delivery than after caesarean section; the normalization occurred within 24 h after parturition. Blood glucose level was significantly higher at 2 h from delivery both in the group of bitches submitted to caesarean section and in those undergoing natural whelping but no statistical correlation was found between maternal glycemia and lactatemia. The results of the present study highlighted that the monitoring of lactatemia during the first 24 h of life, in association with the assessment of the APGAR score at birth, can be an useful prognostic tool helping to identify the most severely distressed puppies and to provide them an adequate support.

Point of Care Measurement of Lactate

Lactate is generated as a consequence of anaerobic glycolysis by all tissues of the body. Increased l-lactate, the isoform produced by most mammals, reflects increased anaerobic metabolism secondary to tissue hypoperfusion or tissue hypoxia in most clinical situations, and is called type A lactic acidosis. The utility of lactate measurement and serial lactate monitoring in veterinary patients has been demonstrated in multiple studies. Blood lactate concentration is significantly elevated in many disease processes including septic peritonitis, immune-mediated hemolytic anemia, Babesiosis, trauma, gastric dilation and volvulus, and intracranial disease. Lactate clearance can be used to assess response to fluid therapy, cardiovascular therapeutics, and blood product transfusion in patients affected by type A lactic acidosis. Lactate concentration in peritoneal, pericardial, and synovial fluid can also be used as a diagnostic tool. Point of care analyzers such as the Lactate Pro, Lactate Scout, Accutrend, iSTAT, and Lactate Plus have been shown to be accurate lactate measurement instruments in small animal patients.

Perioperative Acid-Base and Electrolyte Disturbances

Obtaining and interpreting blood gas and electrolyte levels is essential in the management of perioperative veterinary patients. Metabolic and electrolyte alterations are common in critically ill surgical patients, and can lead to alterations in cardiovascular function, neurologic status, respiratory function, and even response to various drug therapies. Several common perioperative conditions are discussed in this article, including metabolic disturbances, electrolyte abnormalities (hyponatremia and hypernatremia, hyperkalemia), and respiratory abnormalities.

Assessment of Fluid Balance and the Approach to Fluid Therapy in the Perioperative Patient

Perioperative patients can be highly dynamic and have various metabolic, physiologic, and organ system derangements that necessitate smart monitoring strategies and careful fluid therapy. The interplay between changing patient status, therapeutic interventions, and patient response makes effective monitoring crucial to successful treatment. Monitoring the perioperative patient and an approach to fluid therapy are discussed in this text.