Analysis of correlation factors of hyponatremia in elderly patients with hip fracture during perioperative period

Abstract

Objective: To examine the risk factors of hyponatremia during perioperative period for elderly hip fracture patients. Methods: Clinical data of 1 001 patients with hip fracture over 60 years old who received surgical treatment at Department of Orthopedics,Seventh Medical Center,People's Liberation Army General Hospital from January 2012 to December 2016 were retrospectively analyzed.There were 327 males and 674 females with a median age of 81 years (range: 60 to 104 years).There were 584 cases(58.34%) intertrochanteric fractures and 417 cases(41.65%) femoral neck fractures.Hyponatremia was defined as serum sodium concentration <135 mmol/L,and patients were divided into admission hyponatremia and postoperative hyponatremia according to the occurrence time of hyponatremia.Postoperative hyponatremia was divided into early postoperative hyponatremia (within 24 hours after surgery) and discharge hyponatremia (within 48 hours before discharge or death).Patients with hyponatremia can be divided into three types according to their condition changes:persistent hyponatremia,transient hyponatremia (hyponatremia on admission,but normal blood sodium after operation),and new postoperative hyponatremia (normal blood sodium on admission,hyponatremia after operation).The incidence rate,occurrence time and type of perioperative hyponatremia in elderly patients with hip fracture were analyzed,and univariate and multivariate Logistic regression analysis was used to examine the related factors of admission and postoperative hyponatremia. Results: Among 1 001 patients,126 patients (12.69%,126/1 001) had hyponatremia on admission,161 patients (16.3%,161/987) had hyponatremia after operation,140 patients (14.6%,140/960) had early postoperative hyponatremia,128 patients (14.0%,128/916) had discharge hyponatremia.Among the 916 patients with complete perioperative blood sodium concentration data,52 patients(5.7%) had persistent hyponatremia,64 patients(7.0%) had transient hyponatremia.Seventy-seven patients(8.4%) had new onset hyponatremia.Univariate analysis showed that age,male,intertrochanteric fracture of femur,white blood cell count,hemoglobin and albumin level were correlated with hyponatremia at admission (all P≤0.05). Hyponatremia at admission,dementia,and general anesthesia were associated with postoperative hyponatremia.Multivariate analysis showed that male(OR=1.788,95%CI:1.196 to 2.674,P=0.005) and white blood cell count(OR=1.116,95%CI:1.041 to 1.195,P=0.002) were independent risk factors for admission hyponatraemia,and albumin level(OR=0.932,95%CI:0.891 to 0.982,P=0.004) were protective factors, admission hyponatremia (OR=6.481,95%CI:4.125 to 10.182,P<0.01) was an independent risk factor for postoperative hyponatremia,while general anesthesia (OR=0.614,95%CI:0.383 to 0.986,P=0.044) was a protective factor. Conclusions: The incidence of hyponatremia in elderly hip fracture patients is high.Male and high level of white blood cell counts are independent risk factors for admission hyponatremia.High level of albumin is a protective factor for admission hyponatremia.Admission hyponatremia is an independent risk factor for postoperative hyponatremia,and general anesthesia is a protective factor for postoperative hyponatremia.