在同次手術雙側膝關節置換病人，觀察其中央靜脈氧氣飽和度之變化

Abstract

研究背景與目的 在膝關節置換的手術過程中，氣壓止血帶是經常被運用的。長時間及高壓止血帶，可能引起肌肉、血管或神經傷害；在釋放時，會伴隨著低血壓、肺栓塞、左心室收縮不良，甚至死亡的案例發生。但隨著人口老化，膝退化性關節炎盛行率激增。有醫師主張在單次手術中連續處理兩膝的問題。為預防大量失血，術中止血帶的應用是絕對必要的。而採取兩側膝關節同時置換的病人，在術中的血液循環是比單側膝關節置換還要多變化的。之前的研究發現，一些在術中後發生的併發症，包括心肌梗塞，手術後病人意識混亂和術後需要加護病房觀察的比率是比較高的。因此，雙側膝關節置換術的病人需要使用其他更多的血液動力學的參數來參與的術中的監測，以預防並意識到對高危險病人致命的顯著的血液動力學的變化，並及時加以處理。中央靜脈氧氣飽和度(ScvO2)已經應用在處理許多重症及休克病人，其施打方便，可以持續偵測全身組織間氧氣需求與供應之間是否平衡，並由其趨勢得知病人變化。但在雙側人工膝關節置換的病人身上，並無中央靜脈血氧飽和度(ScvO2)變化比較之文獻。因此我們此次研究的目的，是要觀察在同時雙側膝關節置換病人中，中央靜脈氧氣飽和度的變化與可能相關因素之關連性。 研究設計： 前瞻觀察性實驗。所有病患皆為ASA II或III，18歲以上，預計實施兩側人工膝關節置換，並排入一般常規手術之病人。術前無血行動力不穩定，臨床及實驗室診斷之資料無不適合作半身麻醉或硬脊膜外麻醉之禁忌症。病人系統性內科疾病，如高血壓、糖尿病、慢性腎臟病等及有無喝酒或抽菸等習慣，術前之血色素，肌酸酐均詳加紀錄。作脊椎麻醉前，先放置中央靜脈管及動脈導管。在腰椎第三四節椎間作半身麻醉。術中全程紀錄動脈壓、心跳、心電圖、動脈血氧濃度(SpO2)及中央靜脈氧氣飽和度(ScvO2)。於誘導完成後，第一次止血帶及第二次止血帶釋放前5分鐘，及釋放後15分鐘，手術後1.5小時，及3個小時從動脈導管取一次血液樣本做分析，包括動脈血液分析。在整個過程中，依病人狀況給予水分及血液並紀錄之。在各個時間點，紀錄尿量，失血量，及輸血，輸液量。手術過程中若病患收縮壓小於100 mmHg，則每次給予每公斤0.2 mg的麻黃素靜脈注射，直到收縮壓超過100 mmHg。統計方式以ANOVA及多變數重複測量分析GEE方法比較各時間點的動脈血液分析變化及與各因素對ScvO2之相關性。(統計顯著為p<0.05) 結論: 在十八位雙側膝關節手術病患中，病患在七個時間點比較動脈血液分析值呈現有意義統計變化，表示病人術中後須抽取動脈血做分析並加以處置。而細胞激素IL-1β於止血帶釋放前後也有意義的上升，表示發炎前趨激素會釋放於血液中使發炎物質產生，而此狀況第二側膝關節手術之上升趨勢比第一側時高。 而在中央靜脈血氧飽和度方面，經過分析發現中央靜脈血氧飽和度與術中血壓並無太大之變化關係。反而是在整個監測過程中，中央靜脈血氧飽和度與病患本身之內科問題，如BMI值、凝血功能、術前之血壓心跳有關；而在術後的時間區段裡，心律不整、心室肥大、抽菸、年紀、及血色素等問題，對中央靜脈血氧飽和度變化有較大的影響。這些因素並不能幫我們完全的估計出實際的中央靜脈血氧飽和度，但由此次的探討統計，我們可以對有這些因素的病患更加的注意其術中與術後之變化。

Tourniquet use is indicated in total knee arthroplasty(TKA), but it has multiple complications such as hypotension, myocardial infraction (MI), pulmonary embolism and reperfusion injury caused by release of free radials, chemokines, cytokines. Although patients undergoing bilateral TKA (BTKR) procedure were criticized to have more perioperative risks of MI，cardiovascular accidents and need more blood transfusion，oxygen supply and post-operative intensive care，many orthopedics surgeons claimed that patients had more satisfaction，rehabilitation，and less cost. Since increased perioperative risks happen，more hemodynamic monitors are needed during and post operative periods. Oxygen satuarion of central vena cava(ScvO2) is commonly used in emergency department and intensive care unit for detection of sufficient oxygen supply. Although it can't really mimic the true level of venous oxygen saturation， the lower ScvO2 (<70%) is thought to be hypoperfusion in early-goal directed therapy trial. Thus we want to use this more convenient and less complications tool to monitor BTKA patients to see if there were any hypoperfusion change during and postoperative periods and the correlation of other hemodynamic parameters. After IRB approved，we collected eighteen patients who received simultaneous BTKR in the operation. Exclusion criteria were severe heart，lung，or liver disease，CVA history，and severe coagulopathy. Patients received combined spinal/epidural anesthesia with arterial catheter and central venous catheter implantation for monitoring vital signs and ScvO2 during the operation. Crystalloid solution was used to supply volume defect if hemoglobin of the patient was above 10 g/dl. Blood pressure, heart rate, SpO2, and ScvO2 were recorded by computer every minute from the start of the operation till 3hours later post second tourniquet release. Blood samples for arterial blood gas analysis and cytokines were drawn at beginning of the operation, five minutes before and fifteen minutes after the tourniquet release, and 90 and 180 minutes after the second tourniquet release. The data was analyzed by using one-way analysis of variance (ANOVA), and repeated measures analysis to analyze blood samples data and to compare the hemodynamic response and ScvO2 changes. We found that the values of pH, pCO2, base excess, HCO3-, Hct and Hb had significant difference during the operation. Interleukin1-β was elevated significantly after second tourniquet was released，and it meant that inflammatory process was increased in BTKR patients. In eleven patients, ScvO2 had dropped below 65% after the tourniquet was released, which meant there had oxygen supply deficit or oxygen consumption increased. Besides, ScvO2 was affected by multiple factors, such as BMI, INR level, pre-operative heart rate and blood pressure. Arrhythmia, LVH, and hemoglobin level affected ScvO2 level post-operatively. All data and previous studies showed that we actually need ScvO2 for monitoring BTKR surgery because standard monitors now we use intraoperatively can not mimic or predict the level of ScvO2 or the balance of oxygen supply and demand.