IOSH92-T-052
隔離病房照顧SARS病患之醫療人員
佩戴動力過濾式呼吸防護具(PAPR)技術手冊
行政院勞工委員會勞工安全衛生研究所
中華民國九十二年五月
摘要
嚴重急性呼吸道症候群(Severe Acute Respiratory Syndrome, SARS)已造成台灣、香港、中國大陸及新加坡等地相當大的傷害，目前台灣遵行美國疾病防治局(CDC)之建議，醫護人員大多穿戴隔離衣並使用N95拋棄式口罩照護SARS病患，雖然N95口罩可提供一般醫護人員足夠的保護，但是當在隔離病房照顧SARS病患之醫療人員執行會產生氣膠(aerosol)治療或插管、抽痰、清理廢棄物等高暴露危害的醫療行為時，病毒量最高，病人由於喉嚨受到刺激，通常會持續咳嗽甚至嘔吐，造成醫護人員受感染之機率增高，應該採取更高等及之防護具，一般可採用更高等級的濾材如N100或P100，也應考慮採用更密合的半面型或全面型面體。一般正確佩戴N95拋棄式防塵口罩雖然也有適當的防護效果，但一天八小時佩戴，常會因醫療行為而造成口罩與臉部密合度短暫時間的降低、再加上長時間佩戴會不舒服、各項防護具搭配密合問題等，可能同時無法提供高暴露醫護人員頭部與臉部最完善的保護，因此勞工安全衛生研究所建議對於加護病房照顧SARS病患之高危害暴露作業逐步改以呼吸防數係數更高、佩戴更舒適，且可以同時提供頭部與臉部防護之具動力過濾式之呼吸防護具(powered air-purifying particulate respirators, PAPR)，以提供第一線醫護人員更完善的保護，使院內感染之機率降至最低。
目錄
自從2003年2月26日越南河內的一位美國商人發病就醫，後來送香港治療後死亡，之後在香港､越南都陸續出現非典型肺炎併發呼吸道衰竭的案例，感染特點為發生瀰漫性肺炎及呼吸衰竭，因較過去所知病毒､細菌引起之非典型肺炎嚴重，因此取名為嚴重急性呼吸道症候群(Severe Acute Respiratory Syndrome, SARS)，SARS目前來源不明，因為尚無抗體、無疫苗、無特效藥、傳染性極高，又有一定比例的死亡率，因而造成防疫上的困難，連帶引起社會大眾的恐慌。
目前所知SARS的傳染途徑是近距離(通常是1公尺以內)的飛沫傳染或密切接觸，對抗SARS的首要方法就是必須找出並隔離傳染源，由於SARS病患前往急診室就診時，若就診原因與SARS無關，醫護人員很難及時發現而採取適當措施。換言之，醫院進出的病人眾多，特別是在急診室，各種病症都有，如果有SARS病人或病患家屬在院內走動，在不知自己染病或「知情不報」的情形下，成為移動式傳染源，將是醫護人員最大的夢魘。
台灣自從四月二十二日和平醫院爆發院內感染事件以後，緊接著又有仁濟醫院之院內感染，頓時醫院成為防治SARS之最慘烈戰場，其主要原因是近日世界衛生組織(WHO)已經證實，SARS之潛伏期是3至14天，病人要有發燒咳嗽等症狀後才會傳染，而出現症狀的第十天時，體內病毒劑量約為第五天或第十五天的千倍以上，此時病人通常都已在醫院中就診，因此院內醫護人員首當其衝，如果防護稍有疏漏，病毒就有入侵的機會，目前第一線醫護人員雖然大都遵行美國疾病防治中心(CDC)之建議穿戴隔離衣、防護衣、防護眼鏡、頭套、手套及N95拋棄式口罩等處理SARS病患，但對於高暴露之醫療行為，應該採取更高等及之防護具，如更高等級的濾材，如：N100或P100，也應考慮採用更密合的半面型或全面型面體。雖然一般正確佩戴N95拋棄式防塵口罩雖然也有適當防護效果，但一天八小時佩戴，常會因醫療行為而造成口罩與臉部密合度短暫時間的降低、再加上長時間佩戴會不舒服、各項防護具搭配密合問題等，可能同時無法提供高暴露醫護人員頭部與臉部最完善的保護，，因此院內感染仍時有所聞，甚至有多位醫療人員受病毒感染而喪失寶貴生命，實在令人惋惜，因此針對隔離病房照顧SARS病患進行插管、抽痰、清理廢棄物等高暴露危害之醫護人員是否需要選用防護係數更高、佩戴更舒適、並可同時提供頭部與臉部完整防護之呼吸防護具及其建議配戴時機，則有進一步檢討改進的空間。
根據美國疾病管制局(CDC)對於預防護理人員感染肺結核病之指引[1]，在醫療院所中使用的呼吸防護具必須達到包括：有效呼吸防護具、適當大小面體、密合度測試、密合檢點等規範：
(1) 對於1微米大小的懸浮狀態粉塵顆粒，其過濾效應必須大於或等於95％(也就是說過濾洩漏小於或等於5％)，流速可達到每分鐘50公升。
(2) 在可信賴的方式下進行定性或定量的密合度測試，得到臉部密合洩漏程度小於或等於10％。
(3) 能夠吻合不同的臉部大小及特徵，此通常可由至少有三種不同尺寸之呼吸防護具而達成。
(4)每次醫護人員戴上呼吸防護具時，可根據美國勞工部職業安全衛生署(OSHA)建立的標準及良好的工業衛生實務(good industrial hygiene practice)檢查臉部(face piece)密合度。
但當醫護人員對疑似患有肺結核的病人進行支氣管鏡檢查或對疑似有活性肺結核的屍體進行解剖時、或清理廢棄物，由於危險程度增高，疾病管制局更要求必須提供醫護人員更高等級的呼吸防護具，例如保護性更高的動力過濾式呼吸防護具(Powered Air-purifying Particulate Respirators, PAPR)或正壓空氣輸氣管半面式呼吸防護具(positive-pressure air-lines, half-mask respirators)。
日前香港[2]及新加坡[3]對於醫護人員在進行可能導致大量產生氣膠之SARS特殊治療，如：插管、抽痰治療、清理廢棄物、或與病人有近距離接觸時，也已經建議醫護人員必須穿戴保護效果更好的PAPR，在完善的防護計畫下，院內感染數因而獲得明顯的改善。
為使國內相關人員對PAPR有進一步的認識，本文特參考美國疾病管制局防止肺結核感染準則、勞工安全衛生研究所編印之呼吸防護具選用技術手冊[4]及國內外相關資料[5-6]，編寫PAPR之使用技術手冊，提供加護病房第一線醫護人員參考，希望能因此避免日後相關醫護人員的傷亡。
1. N-95級或以上之拋棄式粒狀物呼吸防護具：
這種呼吸防護具可去除吸入空氣中的微小懸浮微粒，並分為可置換濾材式(如圖1)與可拋棄式(如圖2)兩種呼吸防護具。美國國家職業安全衛生研究所在防塵呼吸防護具濾材的分類與測試上，因考慮到部份防護具的濾材可能因油性氣膠(oil aerosol)的附著，而失去其以靜電方式捕捉粒子的作用，因此將濾材依防護特性分為N、R、P三類：N為Not resistant to oil，此種濾材無法使用在含有油性氣膠的工作環境中；R為Resistant to oil，濾材不受油性氣膠存在之影響，但僅可連續或間歇使用在八小時以內；P為Oil proof，其可完全防油性氣膠之干擾，而使用期限則由製造廠商訂之。每一種型態的濾材再依其可捕捉粒子的百分率，也就是過濾效率，分為95、99、100三個等級，其分別代表可捕捉95%、99%與99.97%的粒子。故對此粒狀物呼吸防護具而言，其濾材可依其型態與過濾效率分為九種：N95、N99、N100、R95、R99、R100、P95、P99、P100。例如：N95的濾材可應用在無油性氣膠的工作環境中，而其可捕捉95%的空氣微粒。
圖1. 可置換濾材式粒狀物呼吸防護具(圖片由3M公司提供)
圖2. 可拋棄濾材式粒狀物呼吸防護具(圖片由3M公司提供)
對過濾效率而言，美國目前採用的是較嚴苛的測試條件，主要包括將濾材置於高溫、高濕(攝氏38度，相對溼度85%)的環境中24小時後，再以最易穿透濾材的0.075微米CMD﹙count median diameter﹚ 之微粒，在高流速(85 liter/min)狀況下，測試其過濾效率(圖3為各類型防塵口罩測試結果圖，一般N95口罩在0.075微米附近捕集效率最差)。已過濾原理，當流速愈高，細小微粒過濾效率會愈差，雖然一般中度工作者的呼吸量為30 liter/min，而測試採用較高的流速，屬於較嚴苛的測試狀況。
圖3. 不同口罩對於顆粒狀有害物濾除效率比較圖(每分鐘85公升流量)
此外，新的測試方法亦要求在整個測試過程中必須均符合各等級之最低要求，也就是說，如：N99的濾材必須在整個測試期間內任何時刻其過濾效果均不可低於99%。由於此測試方法是將濾材置於最嚴格的條件下測試，因此在選用防護具時，可不再需要考慮所暴露之微粒大小、工作環境中的溫濕狀況等因子，使選用更為簡易，是其最大的優點。因此，就預防細菌或病毒而言，有數種除微粒用呼吸防護濾材可供選擇，包括：HEPA (高效率濾材)，N，P 或 R 系列的防護濾材。惟應注意的是，當在一個經消毒過的房內工作時（如：開刀房），請不要使用具有排氣閥的除微粒用呼吸防護具（尤其是SARS病患），因為來自醫療工作人員呼出氣體中的微粒，可藉由排氣閥散播至外界，可能因此而污染了開刀的工作場所。
N95、N100、P100等拋棄式防護具之優點為重量輕，攜帶方便，且成本低廉，設計上當配戴者吸氣時，外界的空氣會經過濾罐過濾後被吸入面罩內。而其缺點則是這種呼吸防護具構造簡單，而且屬於負壓式設計，由於配戴者吸氣時，易導致呼吸防護具內形成負壓狀態，。而這種因吸氣過程導致的負壓現象，對於拋棄式口罩，外界空氣中的污染物仍可能因為短暫時間的密合度降低而進入呼吸系統內。
當然也可採更高等級的防護具面體，如半面型麵體﹙half mask﹚或全面型面體﹙full mask﹚，利用有彈性的橡膠面體，使得呼吸防護具更密合佩戴者臉型，但仍有因疏忽而造成短時間洩漏之風險。因此，使用這類呼吸防護具時必須依照包裝中製造商的建議方式，每次佩戴都應檢點密合情形﹙fit check﹚，第一次或定期應該測試呼吸防護具與配戴者面頰密合的情形(fit test)，其目的是為了能選擇適於配戴者臉型之呼吸防護具，同時也檢查是否已正確地配戴呼吸防護具，以便能維持最佳密合狀況。但這些面體都會有一樣問題，當醫護人員戴上口罩後，會造成佩戴者與外界的溝通困難、長時間佩戴會不舒服、全面型面體會因呼氣中水分致使面具內起霧、再加上與各類型頭部護具之搭配問題，對於高風險的醫療行為時，可能無法提供醫護人員頭部與臉部最完整的保護。
2. 動力過濾式呼吸防護具(PAPR)：
動力過濾式呼吸防護具是以個人攜帶的送風機提供佩戴者呼吸所需的空氣，風扇及電池一般是掛帶於佩戴者之腰帶上或頭罩後端，送風機促使外界空氣在進入面體前通過濾材，因此佩戴者無需使用肺力。PAPR (圖4)是一種腰掛式的高效能微粒過濾呼吸防護具，這種呼吸器一般裝有高效率濾材，粉塵過濾效能高達99.97%之N100粉塵過濾材或高效率濾材(high efficiency particulate airfilter, HEPA)，在重複使用PAPR時，須注意一段時間後更換新的濾材，也需定期充電，確保抽氣機(air pump)有足夠電量。PAPR若採高效率濾材，可防護空氣傳播之粒狀污染物包括粉塵、燻煙、霧滴與放射性粉塵，主要組件包括主機、高效能濾網、電池、腰帶、呼吸管、頭罩及流量指示計，採用一鼓風機將含污染物的空氣帶至高效能過濾濾材處過濾，以去除污染物，如此可提供乾淨的正壓空氣至防護具內。當可拋棄式或可重覆使用之前述呼吸防護具無法提供適當保護時，或是執行特殊危險性工作如：支氣管鏡檢、抽痰、插管、驗屍或清除廢棄物時，係病毒量高峰期，病人由於喉嚨受到刺激，通常會持續咳嗽，此時醫護人員受感染之機率最高，應該更提升防護等級。而一般供氣式呼吸防護具受到隔離病房設計因素及可能造成醫護人員行動不便之限制，建議逐步改以防護係數較高、佩戴較舒服、且具同時保護頭部與臉部功能的動力過濾式之呼吸防護具(PAPR)取代現有N95拋棄式口罩，以提供高暴露之第一線醫護人員更完善的保護，使院內感染之機率降至最低。
圖4. 動力過濾式呼吸防護具(PAPR) (圖片由3M公司提供)
此種呼吸防護具所使用的面體包括半面體、全面體與各類寬鬆面體 (如圖5至圖7)。
圖5. 配有全面體的動力過濾式呼吸防護具基本構造(HSE, 1990) (7)
圖6. 設於頭盔內的動力過濾式呼吸防護具基本構造(HSE, 1990)
圖7. 與面盾配合使用的動力過濾式呼吸防護具(HSE, 1990)
相較於上述N95拋棄式口罩，PAPR的優點是(1)無呼吸阻力問題，佩戴者的舒適度較佳，(2)若送風機可提供充分的送風量，面體內壓力可保持於正壓狀態，較無密合不良所造成的污染物內洩問題，(3)使用全面體與寬鬆面體時，有較大量的空氣流經頭部，在高溫作業下具冷卻效果，及(4)結合頭盔或氣罩等型式的寬鬆面體，增加佩戴者作業安全性與作業相容性，也可取代眼罩、面罩等各類頭部護具，減少搭配所產生的問題。根據美國工業標準ANSI Z88.2-1990所定之呼吸防護具指定防護因數，無動力過濾式的拋棄式口罩，其防護因數只有10，反之動力過濾式的全面體、頭盔或頭罩+高效率粒狀污染物防護濾材組合之防護具防護因數甚至可高達1,000，因此可提供穿戴者更大的保護作用。
PAPR的缺點則是購置成本較高，因其配製了電池而形成體積較為龐大，並有些微的噪音困擾，它並不是絕對的正壓式防護具(也就是說外界污染物仍可能經漏縫進入防護具內)，而且需要較嚴密的穿戴訓練及保養維護方能發揮應有的功能。
半面與全面式的PAPR面體一般有三種尺寸，至於非密合式(loose-fitting) 的PAPR (如：頭罩、頭盔等)則只有一種尺寸去適合任何人配載，如發現濾罐遭受損壞或污損時則必須拋棄不再使用。
由於動力過濾式呼吸防護具是藉助濾材過濾空氣中的有害物，所以此類呼吸防護具具有與無動力過濾防護具類似的使用限制(AIHA, 1991 (8); 勞委會，1993 (9))，這些限制包括︰
(1) 不得使用於空氣中氧氣濃度低於19.5%之環境中。
(2) 不得使用於空氣中濃度達到立即致健康損失或死亡濃度(Immediately Dangerous to Life or Health, IDLH)，但若使用密閉面體，可供立即致危險狀況突發時緊急撤離使用。
(3) 與過濾式呼吸防護具一樣，必須針對污染物之特性選擇濾材。
(4) 與防毒面具一樣，不宜使用於無警告性質的有害氣體與蒸氣。
(5) 對於高毒性粒狀物質、石綿與輻射核種應使用高效率濾材(如獲得美國防護具認證標準合格通過之高效率粒狀物防護HEPA濾材、獲得歐盟防護具認證標準合格通過之P3濾材、獲得日本工業標準合格通過之微粒物質防護濾材)。
(6) 使用寬鬆面體在故障與流量降低時，完全喪失防護功能。
(7) 在高溫與重體力作業場所，當佩戴者呼吸量增加時，可能無法提供足夠的呼吸空氣量，而使面體內的壓力在吸氣時無法保持正壓狀態。
(8) 防護具宜附設空氣流量警告裝置，或者根據製造商所提供的使用指引檢查空氣流量。
(9) 由於電池、風扇等元件可能在操作運轉期間產生火花，故不宜使用於有火災、爆炸之虞的場所，特別是危險物濃度接近或超過爆炸下限的狀況。
動力過濾式呼吸防護具面體與濾材等部份之使用檢查與無動力過濾式呼吸防護具大致相同，敘述如下︰
1. 面體︰
(1) 是否有積垢或沾覆過多的灰塵。
(2) 是否有裂痕、破損、穿孔或變形的現象。
(3) 塑膠材質是否有彈性疲乏或變質的跡象。
(4) 全面體的視鏡是否有裂痕、嚴重擦傷或鬆動。
(5) 全面體的視鏡是否安裝妥當、視鏡安裝夾是否破損或遺失。
(6) 濾材外殼是否破損、與面體連接的螺牙是否磨損、墊片是否缺損。
2. 頭部繫戴
(1) 是否破損斷裂。
(2) 是否喪失彈性。
(3) 鬆緊調整扣是否破損、變形或喪失功能。
(4) 止滑凸痕是否磨損而造成打滑。
3. 排氣閥
(1) 是否有清潔劑殘質、粉塵微粒、毛髮等異物卡在閥座上。
(2) 材料是否有破損、變形、捲曲等現象。
(3) 是否不當安裝於面體上。
(4) 閥門蓋是否破損或遺失。
4. 濾材
(1) 所使用的濾材是否對所欲防護的有害物具備過濾功能(可參考購買時隨產品附送之技術說明書或者是廠商型錄)。
(2) 是否不當安裝。
(3) 是否容易與面體鬆脫。
(4) 墊片或與面體連接的螺牙是否磨損。
(5) 是否已超過使用期限。
(6) 外殼是否磨損。
(7) 吸收罐安裝於面體之前檢查膠帶、箔片等覆蓋於出口處的密封材料是否存在且完整，以確認吸收罐是全新品。
5. 動力組件
另外，動力過濾式呼吸防護具在使用前還需確定提供氣流的動力組件是否正常，所應檢查的項目包括︰
(1) 電池外形是否完整，接頭是否保持良好通電狀況。
(2) 啟動動力，確定運轉正常。
(3) 根據廠商所建議的方法(如風速計或防護具內附的警告裝置等)，確定風量是否正常。
使用動力過濾式呼吸防護具前，雇主應確定其員工已完成本呼吸防護具相關之教育訓練，包括呼吸防護具穿戴、保養與清潔等訓練，在每次使用完畢後，應清潔與檢查動力過濾式呼吸防護具是否有損壞或者是檢查可能影響防護之零配件(相關之零配件可參閱廠商提供之使用者手冊)。
呼吸防護具之清潔可分為個人專用呼吸防護具之清潔及多人共用呼吸防護具之清潔兩種︰
1. 清洗
個人專用呼吸防護具應盡可能經常清洗：供氣式 (atmosphere supplying) 和緊急狀況用的呼吸防護具，每次使用後都要清洗和消毒)。
(1) 備料
◆兩個桶子(容量7.5公升以上)
◆溫水
◆溫度計
◆無酒精拭布、及/或軟刷、海棉
◆中性清潔劑--不含油脂(多數清潔劑都可使用)
◆桌子或可用的平面
(2) 清洗步驟
※準備水溫不超過43。C(110。F)的乾淨溫水。
※將呼吸防護具拆開，除呼吸閥不要拆掉外(因容易遺失)，移去濾罐(或/及濾片)及連接管、罩子、頭盔、鏡片崁墊等配件。
※第一桶，清潔液(7.5公升)，以無酒精拭布清理呼吸防護具面體和配件(不包括濾罐和濾片)，或浸泡於含中性清潔劑(不含油脂)之溫水中，以軟刷或海棉清洗，不要刷鏡片。
※第二桶，清水，可能的話，活水洗濯(rinse)比浸泡好，以防止清潔劑或消毒劑殘留在呼吸防護具表面。
※清洗約20個呼吸防護具後更換清潔液和清水。
※將清洗後呼吸防護具置於無污染空氣的環境下風乾，避免用熱或置於太陽底下乾燥。
※風乾前後組裝呼吸防護具均可，使用前參照製造商使用手冊建議確認呼吸防護具重裝正確，尤其是吸氣閥及排氣閥的位置。
2. 消毒
(1) 備料
◆兩個桶子
◆溫水
◆溫度計
◆有刻度量筒
◆四級銨消毒劑、或次氯酸鹽(家用漂白液)、或碘液、或其他呼吸防護具製造商推薦用來滅菌之商品
◆桌子或可用的平面
(2) 消毒步驟
※依上述方式清洗呼吸防護具，不必風乾。
※準備兩桶乾淨溫水，水溫建議在43。C (110。F)以下，不要使用滾水和熱水，依下述順序處理。
※第一桶，消毒液，四級氨消毒劑(1包泡7.5公升或依製造商的建議)，或家用次氯酸鹽漂白劑(30毫升泡到7.5公升，或碘水溶液(含碘50 ppm，或0.8毫升碘酒以溫水稀釋至1公升)，將呼吸防護具浸泡於消毒液中，。
※第二桶，清水，以新鮮溫水洗濯，以防止清潔劑或消毒劑殘留在呼吸防護具表面。
※清洗約20個防護具後更換消毒液和清水。
※清洗後呼吸防護具置於無污染空氣的環境下風乾，避免使用熱或置於太陽底下乾燥。
※風乾前後組裝防護具均可，使用前參照製造商使用手冊建議確認防護具組裝對位，尤其是吸氣閥及排氣閥的位置。
3. 清洗和消毒
本清理步驟適用於多人使用同一呼吸防護具時，呼吸防護具交給他人使用前一定要清洗和消毒乾淨，(供氣式和供緊急使用的呼吸防護具，每次使用後都要清洗和消毒)
(1) 備料
◆4個桶子和上述"清洗"及"消毒"所列之用品
(2) 消毒步驟
"清洗"處理後，不必組裝，繼續以"消毒"處理。
一般注意事項：
※清洗步驟應該包括：清洗→消毒→洗濯→風乾→重組→使用前檢查。
※以20個呼吸防護具為一批，每清洗或消毒20個更換清水及清潔液。
※一次拆洗一個防護具比一次拆洗多個佳，以避免不同防護具零件混淆。
※不同防護具製造商可能有不同的清潔劑和消毒劑，和廠商聯絡以充分了解他的產品。
※四級銨(quaternary ammonia)是一種含NH4＋和界面活性劑之消毒劑，常用在牧牛者和動物護理人員，殺菌(germicidal)範圍廣，無腐蝕性，乾淨的表面消毒效果極佳。
※其他：已有廠商建議使用非鹼性生物分解消毒劑來消滅愛滋病毒HIV-1。
1. 勿將動力過濾式呼吸防護具之主機浸泡於清潔液中。
2. 避免污染物進入呼吸管。
3. 不可使用任何含有機溶劑之溶劑擦拭動力過濾式呼吸防護具，可使用棉布沾些許中性清潔劑進行清潔工作。
4. 可將呼吸管拆卸浸泡於中性清潔劑中進行清潔工作。
5. 完成所有零配件清潔與檢查工作後，待所有零配件自然陰乾與完成電池充電後，將所有動力過濾式呼吸防護具之零配件收藏於乾淨、乾燥、無太陽光直曬且溫度低於48℃之儲存場所。
在使用者進入作業環境前，務必確認流量指示計內下標標示高於呼吸管之邊緣，因為供氣量不足可能導致使用者發生傷害或死亡，進入作業環境後應全程使用呼吸防護具，未能全程使用可能導致使用者發生傷害或死亡。
有下列情形應立即離開作業環境︰
1. 呼吸防護具設備有損壞時。
2. 呼吸防護具供應氣流量有下降情形時。
3. 呼吸困難時。
4. 感覺到精神不佳或視野模糊時。
5. 有聞到或嗅到污染物存在時。
6. 感覺到臉部、眼睛或口鼻有受到刺激時。
7. 污染物濃度增加至呼吸防護具不適用時。
*為防止醫護人員在隔離病房照護SARS病患時，因為PAPR功能出現問題如：電力中斷、送風量不足等而造成立即性危險，必要時可再於頭罩內配戴N95拋棄式口罩，以達進一步的保護。
PAPR目前有3M、Drager、Wilson、MSA、North等數家廠商生產，以3M PAPR為例，每套約美金$500元，再加其他備用之N100粉塵過濾板及抽氣機大約美金$100元，總價每套約美金$600元。
國內目前有12家SARS專責醫院，隔離病房約有100間，預估共約需要500-800套，因PAPR可重複使用，僅需定期更換其中的N100粉塵過濾板，電池使用八小時後充電約需12小時，因此每套PAPR約需準備20∼30片N100粉塵過濾板、至少一組備用電池及10個拋棄式頭罩，以備更換使用，近期國內PAPR供貨應即可正常，廠商宣稱1∼2個月內可完成交貨，且可派人直接訓練使用者或協助指導訓練者。
當醫護人員冒著生命危險，全力以赴救助病患時，應提供適當且足夠的裝備給這些醫護人員穿戴，使這些抗疫英雄在戰場上能無後顧之憂，期能早日打贏這場防疫戰。
照護SARS病人之醫護人員有不同的醫療作業，其危險程度也不盡相同，建議至少分成下列兩個等級佩戴防護具，使每個人都能得到適當的保護且不會造成資源浪費︰
(1) 於高度危險醫療行為時，例如：與病人近距離接觸，執行可能會產生氣膠(aerosol)治療或插管、抽痰、清除SARS病患等高暴露危害的醫療行為，有可能接觸病人體液或分泌物者，建議應由有經驗的醫療人員，配戴動力過濾式呼吸防護具（PAPR）或供氣式防護具執行工作。
(2) 其他一般中、低度危險區服務之醫療人員，則建議仍維持配戴N95以上的口罩。
本資料由勞工安全衛生研究所汪禧年研究員、石東生組長、衛生組陳春萬副研究員、葉文裕組長及工研院環境及工業安全衛生技術發展中心黃奕孝組長合作彙編。
1. CDC. "Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994", MMWR 1994; 43(No. RR-13).
2. CDC. "Safe Handling of Human Remains of Severe Acute Respiratory Syndrome (SARS) Patients: Interim Domestic Guidance", 2003.
3. "Statement from the Minister for Health: Coping with SARS", Singapore Government Press Realease, 2003.
4.陳友剛、葉文裕、陳春萬：防護具選用技術手冊-呼吸防護具，勞工安全衛生技術叢書IOSH84-T-009。
5.張靜文：空氣中生物性危害與呼吸防護，勞工安全衛生簡訊第33期。
6. "3M Air-MateTM高效能動力濾靜式呼吸防護具使用說明"，台灣明尼蘇打礦業製造股份有限公司。
7. HSE (1990), Respiratory Protective Equipment, A Practical Guide for Users. HMSO.
8. AIHA (1991). Respiratory Protection, A Mannual and Guideline. 2nd. Ed. (Colton, C. E., Birkner, L. R., Brosseau, L. M. eds) American Industrial Hygiene Association, Fairfax, VA, USA.
9. 勞委會(1993)：如何正確使用呼吸防護具；行政院勞工委員會。
10.鄭蓉瑛：你的呼吸防護具該洗囉，勞工安全衛生簡訊第52期。
Safe Handling of Human Remains of Severe Acute Respiratory Syndrome (SARS) Patients: Interim Domestic Guidance
May 15, 2003, 3:30 PM EST
The Centers for Disease Control and Prevention, HHS, has received reports of outbreaks of a respiratory illness, being referred to as Severe Acute Respiratory Syndrome, or SARS.
Interim recommendations for infection control precautions for patient care can be accessed at this page and include Standard, Contact, and Airborne precautions (1).
All postmortem procedures require adherence to standard precautions with use of appropriate personal protective equipment (PPE) and facilities with appropriate safety features. Mechanical devices used during autopsies can efficiently generate fine aerosols that may contain infectious organisms. Thus, PPE should include both protective garments and respiratory protection as outlined below.
Personal protective equipment
For autopsies and postmortem assessment of SARS cases, PPE should include:
· Protective garments: surgical scrub suit, surgical cap, impervious gown or apron with full sleeve coverage, eye protection (e.g., goggles or face shield), shoe covers and double surgical gloves with an interposed layer of cut-proof synthetic mesh gloves.
· Respiratory protection: N-95 or N-100 respirators; or powered air-purifying respirators (PAPR) equipped with a high efficiency particulate air (HEPA) filter. PAPR is recommended for any procedures that result in mechanical generation of aerosols, e.g., use of oscillating saws. Autopsy personnel who cannot wear N-95 respirators because of facial hair or other fit-limitations should wear PAPR.
Autopsy procedures
For autopsies and postmortem assessment of SARS cases, safety procedures should include:
· Prevention of percutaneous injury: including never recapping, bending or cutting needles, and ensuring that appropriate sharps containers are available.
· Handling of protective equipment: protective outer garments must be removed when leaving the immediate autopsy area and discarded in appropriate laundry or waste receptacles, either in an antechamber to the autopsy suite or immediately inside the entrance if an antechamber is not available. Hands should be washed upon glove removal.
Engineering strategies and facility design
· Air handling systems: autopsy suites must have adequate air-exchanges per hour and correct directionality and exhaust of airflow. Autopsy suites should have a minimum of 12 air-exchanges per hour and should be at a negative pressure relative to adjacent passageways and office spaces. Air should not be returned to the building interior, but should be exhausted outdoors, away from areas of human traffic or gathering spaces (e.g., off the roof) and away from other air intake systems. For autopsies, local airflow control (i.e., laminar flow systems), can be used to direct aerosols away from personnel; however, this safety feature does not remove the need for appropriate personal protective equipment.
· Containment devices: biosafety cabinets should be available for handling and examination of smaller specimens. Oscillating saws are available with vacuum shrouds to reduce the amount of particulate and droplet aerosols generated. These devices should be used whenever possible to decrease the risk of occupational infection.
References
1. Garner JS. Guideline for isolation precautions in hospitals. Infect Control Hosp Epidemiol 1996; 17:53-80.
Singapore Government Press Release
Media Relations Division, Ministry of Information, Communications and the Arts,
MITA Building, 140 Hill Street, 2nd Storey, Singapore 179369
Tel: 6837-9666
STATEMENT FROM THE MINISTER FOR HEALTH:
COPING WITH SARS
Introduction
Just one month ago, Severe Acute Respiratory Syndrome or SARS was not even in the medical vocabulary. Today, Singaporeans are concerned and anxious about the spread of this new disease and how it would affect their health and that of their family.
How it all started, 6 - 15 March 2003
On 6 March, WHO alerted MOH that several hospital staff in the French Hospital in Hanoi had developed an unusual respiratory illness after treating an American patient who had severe pneumonia. Our hospitals had identified three Singapore patients who had developed atypical pneumonia. Nothing was known about SARS then. However, MOH instructed the hospitals to isolate the patients and to take all the necessary infection control precautions.
We also started contact tracing investigations of the three cases and found out that they had all stayed in the same hotel in Hong Kong. TTSH and SGH carried out various laboratory investigations to try to determine the cause of the pneumonia in the three patients. However, no definite cause could be found.
On 12 March, it was reported that the hospital in Hanoi had closed after 16 of its staff contracted an unidentified illness after an American patient was treated there for severe atypical pneumonia. On the same day, the Department of Health in Hong Kong issued a press release that some staff at the Prince of Wales hospital had developed an unusual respiratory illness. WHO issued a global alert about cases of a severe form of atypical pneumonia in Hong Kong and Vietnam that particularly affected hospital staff.
On 15 March, WHO coined the term Severe Acute Respiratory Syndrome (SARS) for the new disease and initiated enhanced global surveillance for the disease.
Current state of knowledge on SARS
SARS is a new form of infection which has been recognised for less than a month. We have learnt much about the characteristics of this illness over the past month but there is much that is still not known.
Firstly, the cause of the infection has not been found. However, both the WHO and the US Centres for Disease Control (CDC) have reported that the infection is likely to be due to a virus from the coronavirus family. Some coronaviruses are known to cause the common cold in humans. However the virus associated with SARS is unlike any known human or animal member of this virus family. So, it is likely to be a new type of coronavirus.
Not knowing the exact virus responsible for SARS means that we still do not have a test which we can use to diagnose if patients are suffering from SARS. We also do not know the specific properties and behaviour of the virus when they affect humans. However, we can draw upon some information that is known about members of the coronavirus family in general. For example, it is known that some strains of the coronaviruses can survive in the environment for up to three hours.
Secondly, we know the incubation period of SARS. WHO and the US CDC have both stated that the incubation period ranges between 2 and 10 days. In the majority of cases, the incubation period ranges from 3 to 7 days.
This information helps us in our contact tracing investigations and in deciding on the period of quarantine for close contacts.
Thirdly, we have a good idea of how the disease develops from our local experience of more than 90 cases so far, and the experience reported by others in the rest of the world. The earliest symptom is a sudden onset of high fever with or without muscle aches. Some patients may also have chills, shivering, cough and headache. After 3 to 7 days, patients may start to have cough and shortness of breath, and X-ray changes of pneumonia, usually after a further 3 to 4 days. In about 80 to 90% of cases, the patient gradually recovers. However, in 10 to 15% of cases, the pneumonia progresses and the patient needs treatment in the intensive care unit with most requiring a ventilator to help them breathe. About 4 to 5% of cases die despite intensive care.
Fourthly, the consensus among the medical community and reflected by the WHO and the US CDC is that persons are most likely to be infectious when they have symptoms, such as fever and cough. From our own experience, it also appears that persons are more infectious when they become more ill. Most of the SARS patients in Singapore have passed on the infection to a small number of people only, and through close contact. However, we have also noted that there are a small number of SARS patients who appear to be highly infectious, infecting a large number of people (super-spreaders). Hence, 3 SARS patients have been responsible for the transmission of the infection to 91 non-imported patients that we have seen so far.
What does this tell us about how SARS can be transmitted? Both WHO and the US CDC believe at present that the main way SARS appears to be spread is through droplet transmission, for example, when a SARS patient coughs or sneezes droplets into the air and someone else breathes these droplets in. Our own experience in Singapore supports this view since almost all of our cases have occurred either among healthcare workers caring for SARS patients in hospital, or family members and friends of the patients who had visited and come into close contact with them.
At present, the bulk of the evidence is that there is little airborne transmission of the infection. Airborne transmission means that the viral particles remain suspended in the air for prolonged periods of time and therefore can infect far greater numbers of people at greater distances. For example, people can get infected by just being in the same room or same plane as an infected person. This has not been the case so far. WHO has stated that thousands of passengers who travelled on the same flights as persons ill with SARS have been traced in Germany, Canada, Singapore and the United States but no cases of SARS had been found among them. This would not be the case if SARS spreads by airborne transmission. We know only of one flight crew who developed SARS and she was an air stewardess who had attended to a person who had SARS on board the flight.
However, we cannot exclude the possibility that there may be some situations where SARS is much more infectious, perhaps through other routes of transmission. For example, the reports on 31 March, of a large number of residents becoming affected by SARS in an apartment block in Hong Kong and the infection of several visitors staying in the Metropole Hotel in Hong Kong suggest that SARS may be transmitted more broadly, perhaps through some common environmental route.
There is as yet, no specific treatment for SARS. WHO has stated that no treatment beyond good intensive and supportive care has been shown to improve the outcome in patients with SARS. With good supportive and intensive care, 80 to 90% of patients with SARS will recover without any complications. Unfortunately, about 4 to 5 % will die despite good intensive care. Treatment with serum from patients who have recovered is still being evaluated.
SARS - the current global situation
I would like to turn now to the overall SARS situation. As of 2 Apr 2003, WHO has reported that SARS has spread to 17 countries.
Due to international travel, SARS can spread quickly to more countries. Even after a country has controlled its local outbreak, a new one can start again from imported cases. In Singapore, 91 cases can be traced to the three original index cases over four generations of infections. In Canada, the 56 cases in Ontario has been traced back to an index case who had travelled to Hong Kong.
According to WHO, the SARS situation in Hong Kong has developed features of concern: a continuing and significant increase in cases with indications that SARS has spread beyond the initial focus in hospitals. There is also the possibility that some transmission in Hong Kong is occurring through some environmental route that links rooms or flats together. Despite the implementation of strict measures to control the outbreak, a small number of visitors to Hong Kong have been identified as SARS cases after their return from Hong Kong. The epidemic in Guangdong province is the largest outbreak of SARS reported and has also shown evidence of spread in the wider community. This has prompted the World Health Organisation to issue an unusual travel advisory for persons to postpone all non-essential travel to Hong Kong and the adjacent Guangdong province.
Regarding Vietnam, WHO has said that the number of cases (58) and deaths (4) has remained stable for nine days in a row. However 1 new case has been reported yesterday. On Singapore, WHO stated that the epidemic is showing a stable pattern, with cases confined to well-documented risk groups and few new cases are being detected.
For the countries in our region, the picture is still evolving. WHO has not reported any cases from Malaysia so far. However, Malaysian media reports have quoted the Malaysian Health Ministry as stating that as of 2 Apr, a total of 59 suspected SARS cases had been reported. There has also been a recent death that had symptoms of SARS but investigations are on going to determine the actual cause of death. As we have close relations with Malaysia and a large number of people move between our countries daily, I briefed the Malaysian Health Minister, Datuk Chua Jui Meng and his officials on 1 Apr. We agreed that we would share information and cooperate in controlling SARS for the benefit of both our countries.
The strategy to control SARS in Singapore
Next, I would like to explain our strategies for controlling SARS in Singapore and the various measures that we have taken.
To control the SARS situation in Singapore, our key strategy is to detect persons with suspected or probable SARS, as early as possible and isolate them in Tan Tock Seng Hospital (TTSH) and Communicable Disease Centre (CDC). Once isolated, we cut off further transmission of the disease. Early identification is being done through several ways.
Firstly, we have been educating the public about the symptoms of the disease and how they can be infected. We urge all those with fever and who have travelled to SARS affected countries or had contact with SARS patients within the preceding 10 days, to seek medical treatment immediately.
Secondly, our GPs, polyclinics, A&E Departments of our hospitals as well as TTSH and CDC have been organised to pick up cases quickly.
Thirdly, each time a new SARS patient is identified, MOH officers quickly carry out investigations to trace all those who have come into contact with them so that these contacts can be ring-fenced through home quarantine. Persons who are quarantined are given instructions to monitor their temperatures daily and to call MOH when they feel unwell. We also check on them daily. We thus ensure that we pick up any person who develops the disease as early as possible and isolate them in the hospital. This quarantine measure also prevents any potential spread to others in the community from delays in getting to hospital.
However, contact tracing is not 100% foolproof. We may not be able to trace everyone who is a contact. So we have to appeal to all Singaporeans that if you or your children are sick with fever, you should not go to work, your children should not go to school but you should see a doctor immediately.
An important characteristic of SARS is that it is more infectious when the patient is sicker. Hence, it tends to be transmitted quickly among healthcare workers who are not appropriately protected when they take care of SARS patients. As such, another key strategy is the implementation of enhanced infection control measures in all hospitals. In addition, my Ministry decided early on to concentrate all SARS cases in TTSH and CDC. All staff in TTSH and CDC practise enhanced precautionary measures to prevent getting infected by patients. These include wearing of tight fitting masks, gloves, gowns and special hoods (PAPR - Positive Airway Pressure Respirators) when they perform higher risk procedures on patients. Staff there also monitor their temperatures three times a day so that any healthcare worker who becomes unwell is quickly isolated. A dedicated set of staff also take care of the SARS patients and they do not see other non-SARS patients. In TTSH, no further spread among the health care staff from treating known cases have occurred after the measures have been fully implemented.
Besides TTSH and CDC, staff members in all hospitals also exercise the necessary precautions when handling patients with fever and pneumonia. Patients who come to the Emergency Departments with a fever and who could be a suspect SARS case are identified quickly and managed separately from the other patients.
With these measures, WHO has assessed that the outbreak here due to the first 3 index cases is coming under control. We are currently working hard to ensure that clusters of infection do not develop from the new imported cases of SARS.
To reduce the number of imported cases, we are carrying out health screening on incoming air and sea passengers from affected areas. This complements the checks that airlines have put in place at check-in counters. Flight crews are also on the lookout for ill passengers on board aircraft. All travellers who enter Singapore are given a Health Alert Notice to explain the symptoms of SARS and how they can get help if they fall ill with suspected SARS. We will also be requiring all visitors to Singapore to complete a Health Declaration Card soon.
The next stage
The indications are that we should be able to control the present outbreak as new infections are tailing off. However, there continues to be a risk that new clusters of infection may develop from unrecognised cases of SARS, particularly in patients with multiple medical problems where the presentation is not typical. In the absence of a definitive diagnostic test, it is very difficult to identify and isolate such cases early. At the same time, global travel means that new imported cases will occur in the future. Screening of travellers at airports and seaports are limited in their effectiveness as it will not pick up persons during the incubation period. Persons can therefore be well as they pass through the screening procedures and develop SARS later. A single imported case can trigger off an outbreak involving many cases, especially if he or she is a super-spreader even though we quickly institute the control measures to isolate and ring-fence ill persons and their contacts so as to limit disease transmission. Hence we must all be prepared to accept that SARS will not just disappear after some time. We are in this for the long haul.
It is important that Singaporeans realise that controlling SARS is not just the job of the MOH or the government. Everyone must play their part to control SARS. There must be a change in mindset, in social behaviours. Heed our travel advisories and do not travel to SARS-affected countries. If you have fever or are unwell, do not go to work. If your child has a fever, do not send your child to school. See a doctor and stay at home until you are well. When you go to the doctor's clinic, wear a face mask so as to reduce the risk of spreading infection to others. If you cough, cover your mouth and nose with tissue paper or a handkerchief. Do not spit on the floor or in the open. Practise good personal hygiene and wash your hands frequently. It is in your own interest and family's interest to work together with the Government to prevent and control SARS in our community. If your are sick and you seek medical treatment immediately, your chances of recovery are better. You are less likely to infect your family. If everyone who has fever and is unwell stays at home and away from crowds, then Singaporeans will have greater confidence that the likelihood of their meeting a very infectious person in a crowd will be much reduced.
SARS is a new threat to our health. As more information on the disease becomes available, we should be able to tackle it more effectively. For example, once we have a diagnostic kit, we can operate with greater certainty. But a vaccine or a cure would take a long time. In the meantime, SARS is likely to be an on-going health threat worldwide. The disease may well flare up around us again in the future. We must be resilient, adopt the necessary precautions and soldier on. If all Singaporeans work together, I am confident we can cope with this disease without unduly disrupting our normal lives.
MINISTRY OF HEALTH
4 Apr 2003
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