Comparison of a method using the HemoCue near patient testing device with a standard method of haemorrhage estimation in dogs undergoing spinal surgery

Objective  To compare an estimate of blood loss obtained using measurements from the Hemocue photometer with a standard estimate in dogs undergoing spinal surgery.
Study design  Prospective clinical study.
Animals  Twenty-nine client-owned dogs.
Methods  During surgery, blood and all lavage fluids were collected in the suction container and on to swabs. To prevent blood clot formation in the suction container, 10 mL citrate-phosphate dextrose adenine (CPDA) was added. At the end of the procedure, the total volume in the suction container was recorded. It was shaken to ensure uniformity and a 5 mL sample tested with the HemoCue photometer. Blood loss in the suction container was calculated as follows: Blood in suction (mL) = volume in bottle (mL) × [suction haemoglobin (Hb) concentration (g dL⁻¹)/pre-operative Hb concentration (g dL⁻¹)]. This volume was added to the estimated volume of blood on the swabs (weight of soaked swabs minus that of dry swabs) to provide the Hemocue estimate of total blood loss. A standard haemorrhage estimate was performed using the volume of fluid in the suction container at the end of surgery in excess of the total volume of lavage fluid available, minus 10 mL CPDA. This volume was added to the estimated volume of blood on the swabs to provide the standard estimate of total blood loss. Data were analyzed with a paired t -test. Retrospective power calculations demonstrated an 80% power to detect a mean difference of 25 mL between the two methods with a level of significance of 0.05.
Results  There was no significant difference in calculated blood loss between the two methods ( p  = 0.8, mean difference: −2 mL, 95% CI: −20 to 16 mL).
Conclusions and clinical relevance  The HemoCue may be used to help estimate blood loss in dogs undergoing spinal surgery.