Gail E. Russell

Sequential plasma lactate concentrations as prognostic indicators in adult equine emergencies

BACKGROUND Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate. HYPOTHESIS Prognosis for survival is decreased in horses with a delayed return to normal [LAC]. ANIMALS Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement. METHODS Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC]deltaT) was calculated from changes in [LAC] between sampling points. RESULTS Median [LAC] was significantly (P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60-18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30-13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17-1.43) at admission to 49.90 (6.47-384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC]deltaT was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24-72 hours (- 0.47, P = .001) and 48-72 hours (- 0.07, P = .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors. CONCLUSIONS AND CLINICAL IMPORTANCE These results indicate that lactate metabolism is impaired in critically ill horses and [LAC]deltaT can be a useful prognostic indicator in horses.

Assessment of a Point-of-Care Lactate Monitor in Emergency Admissions of Adult Horses to a Referral Hospital

BACKGROUND Blood lactate concentration [LAC] is considered a useful indicator of disease severity in horses. Agreement of point-of-care (POC) lactate monitors with laboratory standards has not been established for clinically abnormal horses. HYPOTHESIS It was hypothesized that results from a POC lactate monitor would be in agreement with a laboratory-based measurement of [LAC]. ANIMALS The study included adult horses presented for emergency evaluation. METHODS A prospective observational study was performed. [LAC] was measured with whole blood (AWB) and plasma (APL) by means of a POC monitor (Accutrend) and compared with results from whole blood measured by a laboratory blood gas analyzer (NOVA). RESULTS Samples from 221 horses were used to compare the 2 lactate measurement techniques. Agreement (p +/- SE) was closest between APL and NOVA (0.97 +/- 0.01); an average observed difference of 0.15 +/- 0.89 (mean +/- SD) and 95% limits of agreement (LOA) -1.89, 1.59 also were found. Agreement was preserved and 95% LOA further decreased in horses with NOVA [LAC] of <5 mM and PCV <40%. Agreement was modest when testing whole blood samples on the POC monitor with increased 95% LOA. CONCLUSIONS AND CLINICAL IMPORTANCE Results indicate close agreement between NOVA and the POC monitor when [LAC] was measured with plasma. Results were less consistent at higher [LAC] but sufficiently reliable to follow trends. Although whole blood may be used with the POC monitor to identify clinically important hyperlactatemia, results may be insufficiently reliable to monitor trends.

Short-term outcome of equine emergency admissions at a university referral hospital.

REASONS FOR PERFORMING STUDY Obtaining data on emergency admission survival rates is important to provide clients with an estimate of prognosis and to identify areas in which improvements in case management can be achieved. OBJECTIVE To determine the short-term outcome of equine emergency admissions to a university referral hospital during a 12 month period. METHODS Short-term outcome was defined as survival to discharge or died/euthanasia during hospitalisation. The overall death (euthanasia) rate was calculated; and rate for horses with different categories of: age; admission month, day and time; presenting complaint (PC); duration of clinical signs prior to presentation; clinical pathology abnormalities; and therapy/therapeutic-related procedures performed was recorded. RESULTS There were 918 admissions. The overall death rate was 24%. Foals (34%) and geriatric (40%) subjects had a death rate that was higher than that for mature horses (21%, referent). The death rate was highest in March (37%). Horses with a PC categorised as neurological (46%) or neonatal (41%) had the highest and as ophthalmological (5%) or trauma/skin (13%) the lowest death rates. There was no difference in death rate between different admission days or times or the duration of clinical signs prior to presentation. The death rates for horses with abnormal peritoneal fluid (71%), coagulopathy (63%), acid-base abnormalities (52%), hypoproteinaemia (47%), dehydration (43%), hypoxia/hypercapnia (48%), leucopenia (44%), electrolyte abnormalities (39%), hyperlactataemia (39%) or azotaemia (35%) were high. The death rate for horses treated with intranasal oxygen (57%), plasma (34%) or polymixin B (35%) was high and for horses undergoing laceration repair/joint (0%) or synovial cavity lavage (4%) was low. CONCLUSIONS Age and critical illness were important contributing factors to a higher death rate. POTENTIAL RELEVANCE Improving the understanding of disease processes in and developing treatment strategies for neonatal and geriatric patients as well as critically ill patients is required.