Comparison of arterial and venous blood-gas values in anesthetized Dorset cross-bred lambs (Ovis aries) using a point-of-care analyzer

Objective: To determine the degree of agreement between arterial and venous blood gases in anesthetized lambs using a point-of-care analyzer. Study design: Prospective experimental study. Animals: A group of 12 female Dorset cross-bred lambs, weighing 37.3 ± 7.4 kg (mean ± standard deviation). Methods: Lambs were anesthetized with isoflurane for catheterization of the jugular vein and femoral artery, and blood samples were collected simultaneously for analysis of pH, PCO ₂ , PO ₂ , base excess (BE), bicarbonate (HCO ₃ ⁻ ), total carbon dioxide (tCO ₂ ), oxygen saturation (SO ₂ ), ionized calcium (iCa) and potassium (K ⁺ ) using the Vet Scan i-STAT handheld analyzer. The Bland–Altman method was used to calculate agreement between arterial and venous measurements. Results: Strong agreement was identified between arterial and venous pH (bias = 0.04; 95% limits of agreement = 0.02–0.06), K ⁺ (bias = –0.1 and 95% limits of agreement = –0.8 to 0.5) and iCa (bias = 0.04; 95% limits of agreement = –0.08 to 0.0003). There was poor agreement for PO ₂ (bias = 168.0; 95% limits of agreement = 77.4–258.7) and SO ₂ (bias = 9.1; 95% limits of agreement = 2.8–15.3), as these values were higher in arterial blood than in venous blood. Moderate agreement was present for BE (bias = 1.7; 95% limits of agreement = –2.7 to 6.1), PCO ₂ (bias = –2.1; 95% limits of agreement = –7.5 to 3.4), HCO ₃ ⁻ (bias = 1.1; 95% limits of agreement = –3.1 to 5.3) and tCO ₂ (bias = 1.0; 95% limits of agreement = –3.3 to 5.3). Conclusions and clinical relevance: Venous blood can be used for the measurement of pH, K ⁺ and iCa in anesthetized Dorset cross-bred lambs. Arterial blood is required for accurate measurement of PO ₂ , SO ₂ , PCO ₂ , HCO ₃ ⁻ , tCO ₂ and BE to assess systemic blood oxygenation and pulmonary function in anesthetized Dorset cross-bred lambs.