Tió M, et al. - Researchers ascertained the blood loss and transfusion needs in severe and morbid obese patients undertaking total knee arthroplasty (TKA). Following primary TKA, greater blood loss or higher red blood cell (RBC) transfusion needs were not demonstrated by severely and morbidly obese patients vs non-obese and obese Class I patients. Possibly, this was noted because obese Class II -III patients had higher estimated blood volume (EBV) but similar RBC losses.

Methods

• Authors retrospectively recorded all patients undergoing TKA.
• They evaluated obesity according to WHO guidelines.
• They recorded the perioperative haemoglobin and treatments for its optimisation.
• An estimation of blood losses was conducted from specific formulae for lost red-cell mass and percentage of lost blood volume.

Results

• As per data, 922 patients were included: 35.90% were obese Class I and 18.76% obese Class II - III.
• Findings suggested that estimated blood volume among non-obese, obese Class I and obese Class II-III was 4390 ± 470 ml, 4736 ± 423 ml and 5030 ± 464 ml, respectively (P < 0.001).
• Results demonstrated that without differences between the three groups, the global estimated blood volume (EBV) lost was 1502 ± 680 ml.
• Nonetheless, in obese Class II -III (29.65%), the percentage of lost blood volume was lower than in non-obese (33.55%) and obese Class I (30.97%) (P < 0.005).
• Transfusion rates for non-obese, obese Class I and Class II -III were 12.7%, 12.1% and 6.4%, respectively (P=0.062).
• Experts predicted a negative transfusion risk for Class II -III patients.