Sonographic assessment of volaemia: development and validation of a new method in dogs.

OBJECTIVES: The aims of this study were to describe a method for the sonographic assessment of volaemia, to determinate inter- and intra-operator variability and to assess the ability to detect blood loss after blood donation in healthy dogs. MATERIALS AND METHODS: The left kidney was identified in a spleno-renal view, and transverse views of the caudal vena cava and aorta were obtained in 12 dogs. Vessel diameters were measured in B-mode, in duplicate by two operators, and the caudal vena cava:aorta ratio was calculated. Intra- and inter-operator variabilities were assessed using a Bland-Altman method by plotting the differences between the repeated measurements obtained from the same subject by the same operator and by the two operators against their means. Before and after blood donation measurements were compared using paired t-tests or one-sample t-tests, if appropriate. RESULTS: Intra- and inter-operator variability was within the limit of agreement for the vast majority of measurements. After a blood donation of 9·8 ±2·2 mL/kg, the mean aorta measurements were not significantly different from those obtained before blood donation (1·11 versus 1·10, P=0·28), whereas the mean caudal vena cava measurements and caudal vena cava:aorta ratios were significantly lower (1·28 versus 1·01, P<0·0001; 1·17 versus 1·01, P=0·0001, respectively). CLINICAL SIGNIFICANCE: The low intra- and inter-operator variabilities in the caudal vena cava, aorta and caudal vena cava:aorta ratio measurements support their reliability and operator independency. The sonographic assessment of volaemia appears to be a promising non-invasive, repeatable point-of-care ultrasound protocol for assessment and monitoring of blood loss. Further studies are needed to assess the sonographic assessment of volaemia protocol in spontaneously bleeding dogs.

Effect of intermittent infusions of glucose-containing crystalloid cardioplegic solution on myocardial tissue lactic acid and recovery of contractility.

The objective of this study was to determine the effects of single or intermittent infusions of cardioplegic solution with glucose (5 gm/L) or without glucose on myocardial tissue lactic acid and recovery of myocardial contractility following 80 minutes of total ischemia at 28 degrees C in the isolated, blood-perfused, beating rabbit heart. Ischemia without cardioplegia increased tissue lactic acid (6.79 mg/gm tissue) above the control value (0.9 mg/gm tissue), p less than 0.0025). Lactic acid following single infusions with (4.19 mg/gm tissue) or without glucose (3.67 mg/gm tissue) was significantly greater (p less than 0.0025) than tissue lactic acid following intermittent infusions with (1.06 mg/gm tissue) or without glucose (1.05 mg/gm tissue). Cardioplegic arrest in all cases significantly decreased tissue lactate accumulation when compared to arrest without cardioplegia (p less than 0.01). The decrease in myocardial contractility demonstrated when no cardioplegic protection was employed (86% recovery) was completely eliminated (100% recovery) with a single-bolus infusion of cardioplegic solution containing glucose (p less 0.025). Intermittent infusions of cardioplegic solution containing glucose (92% recovery) and single infusions without glucose (93% recovery) also improved recovery of contractility following ischemia, but the results were not statistically significant.