CURRENT FLUID ADMINISTRATION IN LOWER LIMB ARTHROPLASTY LEADS TO HYPONATRAEMIA AND WEIGHT GAIN

Abstract

Excessive perioperative administration of intravenous fluid during lower limb arthroplasty may be associated with postoperative complications. There have only been five randomised trials that have evaluated the effects of intraoperative fluid on recovery time, none of which have looked at Orthopaedic patients. Intravenous fluid overload has been shown to decrease muscular oxygen tension, produce general oedema, delay tissue healing, compromise cardiorespiratory function and can cause coma.

This study assesses the current practice in the administration of fluid and sodium during and after lower limb arthroplasty in our hospital.

A series of 68 patients who have undergone elective THR (57) and TKR (11) were included in this prospective study. Current fluid management includes the use of Hartmans solution at a rate of 125mL per hour together with fluid boluses to maintain blood pressure and urine output. We looked at the weight of the patients before and after surgery and compared this with their pre and post operative serum sodium level.

Our findings were that patients gained an average of 1.84 Kilograms (Range −1.6 to +6.4) which was age dependent and there was a mean fall in Serum Sodium of 5.26 mmols/L (Range −15 to +2). Of note there was a mean fall in serum Haemoglobin of 3.69g/dL (Range −2.8 to −5.9) which may be due to blood loss perioperatively but haemodilution due to excessive fluid administration may also contribute.

We propose responding aggressively to low urine output and low blood pressure can cause detrimental effects on Sodium Haemostasis. Factors such as preoperative Bendroflumethiazide and enthusiastic nursing regimes to encourage oral water intake were found to be contributory factors. Our results suggest that anaesthetists should be aware of post operative hyponatreamia in these patients and a more cautious approach to fluid management is required in the perioperative period.