Is postoperative hyponatremia a real threat for total hip and knee arthroplasty surgery?

Abstract

Postoperative hyponatremia (POH) is thought to be a fearsome complication of orthopedic surgery. Primary aim of this cohort study was to evaluate the incidence of POH and its clinical relevance in elective surgery, outlining differences between total knee arthroplasty (TKA) and total hip arthroplasty, looking for the presence of any risk factor commonly related to POH. Four hundred two patients that underwent total hip arthroplasty and total knee arthroplasty performed between 2016 and 2017 were retrospectively examined. Serum electrolytes, hemoglobin, hematocrit, glucose, and creatinine were evaluated preoperatively and at day 0-I-II from surgery. Age, sex, body mass index, comorbidities, drugs, surgery data, transfusions, postoperative symptoms, and length of stay (LOS) were determined. All surgeries were performed by the same equipe. Patients had the same perioperative management, excluded those that took thiazides, already at risk of POH. Patients were divided in 2 groups: group A, patients with normal postoperative natremia (294 patients) and group B, patients who developed POH (108, 26.9%); 66.7% of these developed POH within 24 hours postoperatively. In group B mean postoperative natremia was 133.38 (127.78–134.85) mmol/L. Two patients (1.8%) developed moderate hyponatremia, no severe hyponatremia was documented. Type of surgery, operation time, LOS, and presence of postoperative symptoms did not show statistically significant differences within groups. At multivariate logistic analysis chronic use of thiazides was the only variable associated to a decreased risk of developing POH (OR = 0.39; P = .03). Hemoglobin postoperative values (OR = 1.22; P = .03), the need of postoperative transfusion (OR = 2.50; P = .02) and diabetes (OR = 2.70; P = .01) were associated to an increased risk of POH. Although 26.9% of our patients exhibited POH, the onset of this disorder had no implication on postoperative symptoms and on LOS. Diabetes and transfusion are factors most often associated to POH.

Hyponatremia Is an Overlooked Sign of Trouble Following Total Joint Arthroplasty

“…Four of those studies utilized large registry databases that, despite including larger cohorts, most likely had inherent biases because hyponatremia was identified using ICD codes as opposed to the actual laboratory measurements 18-20,25 . The remaining studies had smaller cohorts 4,5,7,9,10,16,17,24,26 , with the largest having a cohort of 2,009 patients, similar to our study 24 . Furthermore, several of those studies solely investigated the association between preoperative hyponatremia and perioperative outcomes 19,20,25 .…”

“…Although there has been a recent push to limit the routine use of laboratory tests in arthroplasty patients 13 , metabolic panels that include sodium levels are nonetheless commonly ordered at most institutions. Several factors have been found to be associated with the development of postoperative hyponatremia, including age, preoperative hyponatremia, the use of thiazide diuretics, and diabetes mellitus 4,9,10,14 . One recent study utilized machine learning algorithms to predict postoperative hyponatremia in a large cohort of TJA patients and noted that age, intraoperative blood loss, operative time, body mass index (BMI), and American Society of Anesthesiologists (ASA) classification were predictive 6 .…”

Can patients with mild post-operative hyponatraemia following elective arthroplasty be discharged safely? A large-scale service evaluation suggests they can

“…6,9 In addition, evidence is accumulating that suggests routine post-operative electrolyte testing is not necessary for all patients. [1][2][3] Our finding that post-operative hyponatraemia is common but does not independently predict re-attendance at ED, and/or readmission to hospital within 90 days suggests that omitting routine post-operative electrolyte testing would leave common, mild, post-operative hyponatraemia unrecognised but that this may be safe. We acknowledge that patients captured here had their hyponatraemia recognised and, if appropriate, managed according to local guidelines, 11 and this may have affected outcome.…”

“…An accumulating body of evidence suggests that routine post-operative laboratory blood testing may not always be necessary and can perhaps be safely omitted in some settings. [1][2][3] Hyponatraemia, defined here as a s[Na] ≤ 135 mmol/L, is a common electrolyte disorder that, when encountered following surgery, often triggers a series of investigations and a prolonged hospital stay. 4,5 As enhanced recovery after surgery (ERAS) programmes become more popular, and the focus moves towards proactive and pragmatic perioperative care with shorter inpatient stays, there is a need to better identify those individuals who are likely to come to harm as a result of hyponatraemia, whilst minimising unnecessary tests for others who are likely to tolerate a small and short-lived drop in s[Na] without complication.…”

Development and Internal Validation of Machine Learning Algorithms for Predicting Hyponatremia After TJA

“…Few studies have attempted to determine which factors may be associated with the development of postoperative hyponatremia. These studies have identified several potential risk factors, including age, the need for blood transfusions, preoperative hyponatremia, electrolyte-free water balance, the use of thiazide diuretics, and diabetes mellitus 1,3,[5][6][7] . However, these studies were limited in that the study populations were small, and thus the studies were prone to being underpowered.…”