Acid base imbalances in ill neonatal foals and their association with survival.

Abstract

Acid-base imbalances observed in human paediatric patients are associated with outcome. Likewise, neonatal foals may have different acid-base imbalances associated with diagnosis or prognosis. To determine acid-base imbalances by the quantitative method in ill neonatal foals and assess their association with diagnosis and prognosis. Observational prospective clinical study. This study included 65 ill neonatal foals (32 septic, 33 nonseptic) admitted to an equine referral hospital from 2005 to 2011with acid-base parameters determined on admission and a control group of 33 healthy neonatal foals. Blood pH, pCO2 , sodium, potassium, chloride, L-lactate, albumin and phosphate concentrations were determined. Bicarbonate, globulin, measured strong ion difference (SIDm ), nonvolatile weak buffer concentrations (Atot ), base excess and its components were calculated. Analysis of covariance (ANCOVA) and multiple linear regression statistical analyses were performed. Results are summarised as mean ± s.d. for normally distributed variables and median [25-75th percentiles] for non-normally distributed ones. A total of 63% of ill foals had respiratory alkalosis and 58.5% had SIDm acidosis. The combination of both alterations was detected in 21 of 65 ill foals and abnormal pH was found in 24 of 65. Compared with healthy foals, ill foals had significantly lower SIDm (nonseptic 31.6 ± 6.3 [P<0.01] and septic 32.0 ± 6.4 [P<0.01] vs. control 40.3 ± 3.1 mmol/l), potassium (nonseptic 3.5 [3.3-3.8; P<0.01] and septic 3.6 [3.2-4.3; P = 0.01] vs. control 4.2 [3.8-4.5] mEq/l) and higher L-lactate (nonseptic 5.1 ± 4.2 [P = 0.01] and septic 5.0 ± 3.7 [P = 0.03] vs. control 2.5 ± 1.3 mmol/l). Significantly higher L-lactate and venous pCO2 were found in nonsurviving (6.4 ± 3.5 mmol/l [P = 0.04] and 51 ± 13 mmHg [P<0.01]) compared with surviving foals. The most common acid-base imbalances observed in ill foals were respiratory alkalosis, SIDm acidosis or mixed respiratory alkalosis with strong ion acidosis. Increased venous pCO2 and blood L-lactate concentration were associated with poor outcome.