對於肺水腫的診斷,個人私下亦有七八分的認同度,但科學講究的是精準的用語與一致性的定義,臨床上對於急性的呼吸窘迫,是以ARDS相稱,在1994年 Report of the American-European consensus conference on ARDS,.為了要統一定義,以利臨床研究計設計不致混淆,將ARDS修正為 acute respiratory distress syndrome,並加入 ALI(acute lung injury)的觀念,兩者的差別在於低氧的程度,詳細如下表
Definition Criteria for ALI and ARDS ***************************************************************** Criteria for ALI 1.Acute in onset 2.Oxygenation: A partial pressure of arterial oxygen to fractional inspired oxygen concentration ratio < 300 mm per Hg (regardless of PEEP) 3.Bilateral pulmonary infiltrates on chest radiograph 4.Pulmonary artery wedge pressure < 18 mm per Hg or no clinical evidence of left atrial hypertension
-------------------------------------------------------------------------------------------------- Criteria for ARDS 1.Acute in onset 2.Oxygenation: A partial pressure of arterial oxygen to fractional inspired oxygen concentration ratio < 200 mm per Hg (regardless of PEEP) 3.Bilateral pulmonary infiltrates on chest radiograph 4.Pulmonary artery wedge pressure < 18 mm per Hg or no clinical evidence of left atrial hypertension ******************************************************************* ALI = acute lung injury; ARDS = acute respiratory distress syndrome; PEEP = positive end-expiratory pressure.
Adapted with permission from Bernard GR, Artigas A, Brigham KL, Carlet J, Falke K, Hudson L, et al. The American-European consensus conference on ARDS. Definitions, mechanisms, relevant outcomes, and clinical trial coordination. Am J Respir Crit Care Med 1994;149(3 pt 1):819.
Report of the American-European consensus conference on ARDS: definitions, mechanisms, relevant outcomes and clinical trial coordination. Intensive Care Med 1994;20:225-32.
可見,胸部X光與排除心源性肺水腫是必要條件,在處置上不必然先確立診斷,因為兩者有重覆的部分,如給氧,緊急時插管正壓呼吸,使用PEEP等,但接下來是否脫水利尿給與強心劑,還是只限水即可,百分之百需要鑑別診斷的,這個病人完全沒有心衰的條件,只見到呼吸道泡沫分泌物,即跳躍性思考到心衰水腫,這是不符臨床訓練規範的。
應老對整個病程的邏輯思考是正確的,樓主會去詢問病人術前術後的意識狀態,並檢查其中樞神經功能,也是體現對腦外傷病患病程可能進展的認知,就這壹點來說,表現是可圈可點。可惜無後續影像學的輔助診斷佐證。
外科醫師在緊急情況下,也作了雙側胸腔穿刺引流,可見也想排除血氣胸的可能性,這些都是正確的臨床操作,最後剩下肺水腫無法排除。臨床上可能造成非心源性肺水腫呼吸窘迫的因素有:
Clinical Conditions Associated with Development of Acute Respiratory Distress Syndrome ------------------------------------------------------------------------------------------------- Direct lung injury Indirect lung injury ------------------------------------------------------------------------------------------------- Pneumonia Sepsis Aspiration of gastric contents Severe trauma Inhalation injury Acute pancreatitis Near drowning Cardiopulmonary bypass Pulmonary contusion Massive transfusions Fat embolism Drug overdose Neurogenic Reperfusion pulmonary edema post lung transplantation or pulmonary embolectomy ------------------------------------------------------------------------------------------------- Adapted from Ware LB, Matthay MA. The acute respiratory distress syndrome. N Engl J Med 2000;342:1338. ------------------------------------------------------------------------------------------------- 在這個病人aspiration pneumonitis與neurogenic pulmonary edema都已提及,pulmonary contusion, fat embolism, severe trauma,其中任一或混合兩種以上的可能性則是個人較為認同的診斷,手術與麻醉則扮演觸發或推波助瀾的角色,使用全身麻醉,麻痺控制呼吸,本身即造成不等程度的肺泡塌陷與氧合障礙,尤其胸部挫傷肺祖織水腫出血,喉罩為低壓阻(low pressure seal)通氣,潮氣量低,進一步加速塌陷不張的速度與範圍,局部與全身的炎症反應,高濃度吸氧(FiO2),與後來的低血氧hypoxemia,交互影響互相作用,有一定的條件造成低氧血症,甚至急性呼吸窘迫。
不管原因是如何,有一點大家都會認同的,那就是術中的氣道管理是不到位的,也是有瑕疵的,這跟病情快速惡化終至不治,有相當的關係。
最後,還是想討論開刀時機(timing)的問題,鎖骨骨折矯正,不像長骨骨折,完全沒有時間急迫的壓力,在多重外傷治療的優先次序是很低的,麻醉科很少能干預外科開刀的意志,但在某些情況下應適時提供風險的評估與建議,比如這個案例,腦損傷惡化與肺部併發症可能性的訊息,有無適時與正確的傳遞給外科醫師及病人或家屬,此舉,關係到發生意外時家屬可接受的程度,也可預防醫療糾紛的發生。 |
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