Haemoglobin concentration measurement agreement obtained from three different devices in anaesthetised horses.

This research compared the accuracy of three methods for measuring haemoglobin concentration in anaesthetised horses. The results suggested that two commonly used tools, the SpHb pulse co-oximeter and the Epoc blood gas analyser, often underestimate haemoglobin levels when compared with the packed cell volume (PCV) method.

Study Design

• The aim of the study was to determine how closely the results from the SpHb pulse co-oximeter and the Epoc® blood gas analyser matched the values derived from the packed cell volume (PCV) method.
• This research was prospective in nature and involved 34 horses undergoing elective surgeries.
• Blood samples were collected from each horse and analysed using the PCV method (which was used as the reference method) and the Epoc® device.

Comparative Analysis

• The researchers compared the haemoglobin concentration results from the SpHb and Epoc® devices to those obtained from the PCV method.
• They utilized Lin’s concordance correlation coefficient (CCC) and Bland-Altman analysis to assess the agreement between the results.
• An acceptable clinical limit of agreement was pre-set at 7% variance from the reference.

Results

• The average haemoglobin concentration derived from the PCV method was 14.6 ±1.8g/dL. But the SpHb and Epoc® devices measured considerably lower levels: 9.6 ±1.5g/dL and 11.0 ±1.8g/dL, respectively.
• The SpHb and Epoc® devices underestimated the haemoglobin concentrations by an average of 4.96g/dL and 3.6g/dL, correspondingly.
• The concordance measured using Lin’s CCC indicated weak agreement, with values of 0.08 for the SpHb and 0.14 for the Epoc®.
• Bland-Altman analysis also showed significant biases and wide limits of agreement, exceeding the acceptable threshold of 7%.

Conclusions and Future Research

• The study concluded that both the SpHb pulse co-oximeter and the Epoc® blood gas analyser poorly agreed with the PCV method, consistently underestimating haemoglobin levels in anaesthetised horses.
• The researchers suggest that further study with larger sample sizes and species-specific device calibration is needed in order to establish the true accuracy and clinical utility of these devices for measuring haemoglobin in horses.