Prediction Of Preoperative Hypocalcemia On Postoperative Delirium In Elderly Patients

Objective The preoperative calcium concentration was monitored by arterial blood gas analysis to explore its correlation with the incidence of postoperative delirium（POD）in elderly patients undergoing orthopedic surgery,and to determine whether the preoperative calcium concentration could be used as a predictor of POD.Methods From January 2018 to December 2018,81 patients who were hospitalized in our hospital and underwent orthopedic surgery（internal fixation of intertrochanteric fracture,femoral head replacement,hip joint replacement）were selected,aged 65 years old or older and gender was not limited,ASA grade I^II.All patients received radial artery puncture and catheterization,invasive arterial blood pressure was monitored,blood gas analysis was conducted before anesthesia,and preoperative calcium concentration was recorded.The mean arterial pressure（MAP）,heart rate（HR）,and blood oxygen saturation（SpO₂）were recorded at the time of entering the opetating room（T0）,at the beginning of operation（T1）,the time of operation began one hour later（T2）and at the end of operation（T3）.During surgeries,the patient’s pulse oxygen saturation SpO₂ was maintained greater than 97%while maintaining the ETCO₂ between 35mmHg⁴5mmHg and the bispectral index（BIS）between 40⁶0.Blood gas analysis was performed 1h again after the operation and the first day after the operation,and calcium ion concentration was recorded.The cognitive status of the patients was assessed using CAM diagnostic criteria within 3 days after surgery.According to the assessment results,the patients were divided into delirium group（POD group）and non-delirium group（NOPD group）for comparative study.Results According to the results of cognitive assessment,there were 16 cases（19.8%）in the POD group and 65cases（80.2%）in the NPOD group.There was no significant difference in age,gender,BMI,preoperative complications（hypertension,diabetes,coronary heart disease）and other aspects between the two groups（P>0.05）.There was no significant difference in intraoperative HR,MAP and SpO₂between the two groups（P>0.05）.There was no significant difference between the two groups in the type of surgery,duration of surgery and choice of anesthesia（P>0.05）.In addition,the preoperative calcium concentration in POD group was significantly lower than that in NPOD group（P<0.05）,and the POD incidence rate in the three groups of mild hypocalcemia group,moderate hypocalcemia group,and severe hypocalcemia group was statistically significant（P<0.05）,the more severe hypocalcemia was,the higher the risk of POD was.Conclusion In this study,the incidence of POD in elderly patients undergoing orthopedic surgery was 19.8%,the preoperative decrease of calcium was significantly correlated with the occurrence of POD,and the severity of hypocalcemia could be used as a reliable predictor of the occurrence of POD.