REVIEW ARTICLE 중환자실에서의기도관리 가톨릭대학교의과대학의정부성모병원외상외과 김성집ㆍ조항주 Airway Management in Intensive Care Unit Sung Jeep Kim, M.D, Hang Joo Cho, M.D. Division of Trauma Surgery, Uijongbu St. Mary s Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea 책임저자 : 조항주경기도의정부시금오동 65-1, 480-130, 의정부성모병원외상외과 Tel: 031-820-5066 Fax: 031-820-3439 E-mail: surgeryman@naver.com In the Intensive Care Unit (ICU), endotracheal intubation is more difficult than that in the operating room and is also associated with a higher risk of complications. An appropriate decision making regarding the need for adefinitive airway, an airway algorithm, and the Rapid Sequence Intubation (RSI) improve the clinical outcome of the ICU patients. The purpose of this article is to review the airway management in the ICU, which includes airway evaluation, airway algorithm, RSI, and rescue techniques. (J Surg Crit Care 2012;2:29-38) Key Words: Airway management, Intensive care unit, Airway algorithm, Difficult airway, Intubation 서론 대부분응급으로시행되는외과중환자실에서의기관내삽관은마취과의사에의해서수술실에서행해지는기관내삽관에비하여더어렵고, 합병증의비율이높다. 이런이유로는외과중환자실에는환자의생리적예비능이제한되는환자가많으며, 응급상황시기관내삽관을준비하는시간과어려운기도인지충분히평가할시간이부족하며, 전산소화에도불구하고저산소증인환자, 저혈압을보이는환자가많으며, 수술실에서는기관내삽관이불가능할경우최후의수단으로환자를깨울수도있지만외과중환자실에서는불가능한이유등이있다. 1-3 또한외과전문의들이기도관리의경험에서다양한편차를보이는점도있다. 이러한기관내삽관의합병증으로는어려운기도, 식도내삽관, 폐흡인등이있으며, 응급상황에서는약 78% 의환자에서이러한합병증이발생한다고한다. 4,5 그러므로이러한합병증을및재삽관을피하기위하여중환자실을담당하고있는외과의사들도고도의 숙련된기도관리법을필요로한다. 이에저자들은중환자실에서기도의평가, 기관내삽관알고리즘, 신속기도삽관술 (RSI) 및전처치약물, 다양한기도확보방법에대해서고찰하고자한다. Decision Making for a Definitive Airway 다음의 3가지경우에기관내삽관이필요하다. 6 기도의유지또는보호에실패하였는가? 개방된기도는적절한산소화와환기에필수적이고, 이물질및위내용물의흡인으로부터기도를보호하는것이중요하다. 의식이있고명료한환자는이물질, 위내용물혹은분비물의흡인을방지하고개방된기도를유지하기위해상부기도근육과다양한보호반사를사용한다. 환자의구강및인두내에분비물이가득하다면이는기도보호가어려워질수있음을의미하는것으로생각해야한다. Journal of Surgical Critical Care Vol. 2 No. 2, October 2012 29
J Surg Crit Care Vol. 2, No. 2, Oct. 2012 Fig. 1. Mallampati classification for grading airways from the least difficult airway (I) to the most difficult airway (IV). Class I: visualization of the soft palate, fauces, uvula, and anterior and posterior pillars, class II: visualization of the soft palate, fauces, and uvula, class III: visualization of the soft palate and the base of the uvula, and class IV: soft palate is not visible at all. 환기또는산소화에실패하였는가? 기도를유지하고보호할수는있지만점진적인산소화실패로기관내삽관후양압환기를해주어야할때이다. 예상되는임상경과는무엇인가? 현재는기관내삽관이필요하지않지만, 자상으로인한목앞쪽의혈종또는흡인성화상과같이향후악화가진행되어기도유지및보호실패가예상되는경우가있다. 또는쇽상태에서부적절한조직관류와대사물질의증가로호흡의피로가진행되어호흡부전이초래될것이예상되는경우가있다. Definition of Difficult Airway Fig. 2. Evaulate 3-3-2; 1: inter-incisor distance, 2: hyoid mental distance, 3: thyroid to floor of mouth. 어려운기도란숙련된의사가마스크환기나기관내삽관등의방법에의해서환기가어려운경우를의미한다. 7 어려운환기란숙련된마취과의사가마스크를가지고 100% 산소를투여하여산소포화도를 90% 이상으로할수없는경우를말한다. 7 어려운기관내삽관이란기관내삽관에성공하기위해서 3번이상의시도가필요하거나 10분이상이걸릴경우를의미한다. 7 어려운후두경이란여러번시도하더라도일반적인후두경으로성대를볼수없는경우를말한다. 7 Airway Evaluation 제일이상적인것은모든환자에대해서중환자실에입원시기도에대한평가를미리해놓는것이다. 왜냐하면응급으로기관내삽관이필요한경우시간이부족하여평가를할수없는경우가있기때문이다. 다양한기도평가방법이있지만여기에서는일부만소개하고자한다. Mallampati Score는수술전평가로서많이사용되며, 인두의구조물을평가하여후두경하에서의어려움을예상하게된다 (Fig. 1). 8 Mallampati Score는환자가앉은자세, 입을크게벌리고 냄새맡기자세 (sniffing position) 을취하고혀를최대한내밀었을때인두의구조물을관찰하며후두경은사용하지않는다. Mallampati score 3 이상은어려운기관내삽관을예상하여야한다. 그러나환자가의식수준이낮거나급성호흡부전인경우평가를할수가없는단점이있다. LEMON 방법은영국에서응급실에서환자의기도를평가하기위해개발된방법이다. 9 L은 Look externally의약자로서작은턱이나큰혀, 큰치아, 짧은목등일경우어려움을예상할수있으며주관적인방법이다. E는 Evaluate 3-3-2의약자로서앞니사이의거리가손가락 3마디가되는지, 악하강의길이가손가락 3마디가되는지, 혀기저부와성문사이의거리가손가락 2마디가되는지를평가하여이이하일경우어려움을예상할수있다 (Fig. 2). M은 Mallampati score의약자이고, O는 obstruction의약자로서 epiglottitis나 peritonsillar abscess 또는외상으로인한출혈로 30 www.surgicalcriticalcare.org
김성집ㆍ조항주 : 중환자실에서의기도관리 Fig. 3. Laryngoscopic grading; grade 1: visualization of entire laryngeal aperture, grade 2: visualization of only posterior commissure of laryngeal aperture, grade 3: visualization of only epiglottis, grade 4: visualization of just the soft palate. Fig. 4. Universal airway algorithm. 인하여 obstruction 이있을때를의미한다. N은 neck mobility의약자로서외상으로인한경추손상의경우경추고정상태일경우를말한다. 일반적으로 LEMON score가높을수록어려운기관내삽관을예상할수있다. LEMON 방법으로어려운기도를인지하는민감도는 20 62% 로낮으며, 특이도는 82 97% 정도로높아, LEMON 방법으로정상으로나오더라도어려운기도일가능성 을배제할수는없다. 10 Cormack 과 Lehane은후두경소견에서따라서 4단계로구분하였다 (Fig. 3). 11 3, 4단계의경우에는어려운기관내삽관을예상할수있다. 어려운마스크환기를예상하는방법으로는나이 56세이상, BMI 26 kg/m 2 이상, 많은수염, 치아의결핍, 코골이의과거력 www.surgicalcriticalcare.org 31
J Surg Crit Care Vol. 2, No. 2, Oct. 2012 Fig. 5. Crash airway algorithm. 등이있다. 12 어려운기도를정확히예측하는방법은아직까지없지만, 이러한기도평가방법으로평가를한다면기관내삽관전에계획을세우는데는도움이될것이다. Algorithm Walls와 Murphy가발표한응급기도알고리즘에는 4가지 (Universal, Crash, Difficult, Failed) 의알고리즘이있다 (Fig. 4 7). 6 Universal airway algorithm은모든환자에서알고리즘의시작 이며, 먼저환자의반응을확인한다. 반응이전혀없거나사망직전이라면붕괴된기도 (Crash airway) 알고리즘으로이동하며, 어려운기도가예상된다면어려운기도알고리즘으로이동하고, 3번이상기관내삽관이실패하거나백마스크환기로 SpO2가 90% 이상유지되지않는다면실패한기도알고리즘으로이동한다. 붕괴된기도알고리즘에서는전처치없이바로기관내삽관을시도하며, 실패한다면백마스크환기로환기가되는지확인한다. 환기가안된다면실패한기도로이동하며, 환기가된다면근이완제를투여후다시한번기관내삽관을시도하게된다 (Fig. 5). 32 www.surgicalcriticalcare.org
김성집ㆍ조항주 : 중환자실에서의기도관리 Fig. 6. Difficult airway algorithm. BNTI: blind nasotracheal intubation. 어려운기도알고리즘에서는먼저도움을요청할기도관리에숙련된의사를부른다. 산소화가유지되지않는다면실패한기도로이동하며, 산소화가되고, 백마스크환기가가능할것이라고생각되면기관내삽관을시도하는데기관내삽관이어려울것이라고생각된다면의식하기관내삽관을고려한다. 실패했지만산소화가유지된다면 back up plan, Plan B로서성문외기도장비나 video laryngoscopy, lighted stylet 등을고려할수있다 (Fig. 6). 실패한기도의경우에도먼저도움을요청한다. 산소화가잘되지않는다면 Plan C로서 Cricothyroidotomy를고려하며, 산소화가된다면 direct laryngoscopy를제외한다른기구들의사용을고려한다 (Fig. 7). 빠른연속기관내삽관 (Rapid Sequence Intubation, RSI) RSI는응급상황에서안전한기도를확보하는데필수적인방법이다. 처음에는수술실에서사용되었으며, 흡인을방지하는데도움을주는방법이며, 현재는응급실이나중환자실에서도널리사용되고있다. 많은연구에서 RSI를시행할경우에기관내삽관의성공율이상승하고, 합병증은감소한다고보고하고있다. 5,13-15 National Emergency Airway Registry II에따르면 7,712건의기관내삽관에서 RSI의성공율은 98.5% 이상으로서 Li 등 5 이보고한 RSI를시행하지않을경우의성공율 82% 보다높게나타났다. 15 RSI는전산소화후기관내삽관을위한무의식과근이완상태를만들기위해효력이뛰어난유도제의투여직후동시에신속히 www.surgicalcriticalcare.org 33
J Surg Crit Care Vol. 2, No. 2, Oct. 2012 Fig. 7. Failed airway algorithm. 작용하는신경근차단제를투여하는것이다. 이것은기관내삽관전에금식이되어있지않은환자에게위내용물의흡인위험이있다는것을예상한시행방법이다. 약물을사용하기전전산소화단계는약물을투여한후삽관이될때까지의무호흡상태에서도환자가안전할수있도록충분한산소를공급하는것이며, 양압환기가필요하지않게해준다. 금기증은상대적인금기증만이있으며, 어려운기도에사용할경우백마스크환기가가능할지평가하여백마스크환기가가능할경우에시행하도록한다. 이러한 RSI에는 Preparation, Preoxygenation, Pretreatment, Paralysis with induction, Protection and positioning, Placement with proof, Post intubation management의 7단계의과정이있다 (Table 1). Table 1. Time table for rapid sequence intubation Time NMB minus 10 min NMB minus 5 min NMB minus 3 min 0 min NMB plus 20 sec NMB plus 45 sec NMB plus 1 min NMB=neuromuscular blocking 7P s Preparation Preoxygenation Pretreatment Paralysis with induction Protection Placement with proof Post intubation management 34 www.surgicalcriticalcare.org
김성집ㆍ조항주 : 중환자실에서의기도관리 Preparation은모니터링장비와혈관을확보하며투여할약물에대한준비및사용할장비를점검한다. 또한시간이있다면어려운삽관여부를평가하며, 실패할경우를대비하여그다음계획 Plan B, Plan C를마련해놓는다. Preoxygenation은마스크환기를통해서폐와다른조직에산소저장을해놓는단계이다. 건강한사람에게 4분간 pure oxygen 을공급한다면, PaO2가약 90에서 400 mmhg 이상올려놓을 Fig. 8. SaO 2 versus time of apnea for various types of patients. 수있으며약 8분정도를숨쉬지않고도 90% 이상산소포화도를유지할수있다. 하지만비만환자나어린이의경우에는 3분도안돼서산소포화도가 90% 이하로떨어진다 (Fig. 8). 16 비만환자에서는 25도상체를올리는자세를취한다면무호흡에서산소포화도를더오래유지할수있다. 17 의식이명료한환자라면보통 8번정도의깊은숨을쉬게한다. Pretreatment는삽관과관련되어발생하는부작용이나환자의기저질환의악화를완화시키기위하여약물을투여하는단계이다. 전처치약물들은유도제 3분전정도에투여한다. 전처치약제로는 Lidocaine (1.5 mg/kg) 이나 Fentanyl (3 mcg/kg) 을주로사용한다 (Table 2). Lidocaine은두개내압의반사적인상승을둔화시키며반응성기도질환에서기도저항의반응성증가를약화시킨다. Fentanyl 은후두경에의한교감신경성반응을약화시키므로두개내압상승과심혈관질환에추천한다. Paralysis with induction은수면유도제투여후근이완제를투여하는단계이다. 수면유도제는 thiopental sodium, midazolam, ethomidate, ketamine, propofol이있다 (Table 3). Etomidate의경우에는혈역학적안정성이있고, 히스타민을분비하지않아반응성기도질환에서안전하게사용할수있다. 하지만 adrenal suppresion의부작용이있다. 18 Ketamine의경우에는심박수와혈압을증가시키고평균동맥압을상승시켜뇌관류압을비교적 Table 2. Pretreatment drugs Medication Dosage Indications Fentanyl Lidocaine 3 mcg/kg 1.5 mg/kg Provides sedation and analgesia in hemodynamically stable patients with the following: coronary artery disease; hypertensive emergencies; arterial aneurysm and dissections; cerebrovascular events. Asthma; COPD Table 3. Induction agents Medication Dosage Indications Cautions Etomidate Propofol Thiopental Ketamine 0.3 mg/kg 2 mg/kg 3 mg/kg 2 mg/kg Polytrauma, existing hypotension Isolated head injury; status epilepticus Normotensive; normovolemic Asthma, COPD Inhibit cortisol synthesis Hypotension Bronchospasm hypotension Head injury Ischemic heart disease Table 4. Neuromuscular blocking agents Medication Dosage Onset Indication Succinylcholine Rocuronium 1.5 mg/kg 1 mg/kg 30 60 seconds 45 60 seconds Default paralytic agent When succinylcholine is contraindicated www.surgicalcriticalcare.org 35
J Surg Crit Care Vol. 2, No. 2, Oct. 2012 Table 5. Intubation care bundle management Preintubation Presence of two operators Fluid loading Preoxygenation for 3 min with NIPPV in case of acute respiratory failure During intubation Rapid sequence intubation Sellick maneuver Post intubation Immediate confirmation for tube placement by capnography Norepinephrine if diastolic blood pressure remains <35 mmhg Initiate long term sedation Initial protective ventilation tidal volume 6 8 mg/kg of ideal body weight, PEEP<5 mmhg, and respiratory rate between 10 and 20 cycles/min, FiO 2 100% for a plateau pressure of <30 cmh 2O NIPPV=non invasive positive pressure ventilation, PEEP=positive end expiratory pressure 안정시킨다. 또한기관지의평활근을이완시켜서기관지확장을일으키므로반응성기도질환자와혈역학적불안정환자에서유용하다. 19,20 근이완제에는 Succinylcholine과 Rocuronium이사용된다 (Table 4). Succinylcholine은탈분극성근이완제로서 kg당 1 1.5 mg을투여한다면 60초후에는충분한근이완이이루어지게된다. 금기증으로는악성고체온증, 고칼륨혈증, 화상, 척수손상, 다발성경화증, Guillain-Barre 증후군, degenerative or dystrophic muscular disease, prolonged immobilization 등이있다. 21 Rocuronium은비탈분극성근이완제로서 Succinylcholine의부적응증일때사용할수있으며, kg 당 1.0 mg의용량으로사용한다. Protection and positioning은보조자가 Sellick Maneuver를통하여 passive aspiration을방지하고양압환기를할때 gastric insufflation을줄이는역할을한다. Sellick Maneuver는 Cricoid cartilage를뒤쪽으로누르면서시행하게되고, 척추기둥의지지를받으면서식도를폐쇄시킨다. 환자가만약구토를한다면즉시 Sellick maneuver를중지하고고개를옆으로돌리고구토물을흡인한다. 환자에게특별한문제가없다면냄새맡기자세를취하게한다. Placement with proof는아래턱뼈의움직임을확인하여근이완제의효과를확인한후에삽관을시행하는단계이다. 아래턱이잘움직여지지않는다면약 15 30초후에다시시도한다. Vocal cord가잘보이지않는다면갑상연골에압력을가하여 BURP (backward, upward,s right, and pressure) 를사용한다면시야에도움을받을수있다. 22 삽관의확인은가슴의움직임을확인하고청진을통해서확인할수있다. 하지만가장정확한방법은 Capnography를통하여호기말이산화탄소를측정하는방법이다. 23 기관내삽관이이루어졌다면 Sellick Maneuver를중지한다. Fig. 9. Gum elastic bougie. Post intubation management는튜브의고정및환자의장시간진정및필요하다면마비를시행하는것이다. 기관내튜브의커프는가능한한최소의부피로서공기가새어나오지않도록해야하는데기관의허혈및 extubation 후에 stridor의위험성을최소화하기위해서이다. 24 Intubation Bundle Jaber 등 25 은중환자실에서 Intubation bundle을통하여저산소증및 cardiovascular collapse 등의 life threatening complication을감소할수있다고하였다 (Table 5). Various Adjunts 기관내삽관을편하게하거나기관내삽관이어려운경우에구난기술 (rescue technique) 로서사용할수있는여러가지장비가 36 www.surgicalcriticalcare.org
김성집ㆍ조항주 : 중환자실에서의기도관리 Fig. 10. Video laryngoscope. 있다. Gum elastic bougie Fig. 9은약 60 cm 정도이며기관내삽관튜브의 introducer 역할을하며끝이약 35도로꺽여있다. Bougie를 trachea에위치시킨후튜브를밀어넣으면기관내삽관이된다. 이러한 bougie는성대가잘보이지않을때성문의입구 (glottis aperture) 가적을때에사용하면유용하다. Bougie가기관으로들어갔을경우 bougie의끝에서기관의링이만져지는것을느낀다. Video laryngoscope Fig. 10은보통 angled blade에비디오카메라가달려있다. 기관내삽관튜브에 stylet을넣어서사용하며튜브의끝이성문안으로들어가는것을볼수있다. 시야가더좋기때문에직접후두경에비해서기관내삽관의성공률이더높은편이며, 특히술자의숙련도가낮을경우에더유용하다고알려져있다. 26,27 Fig. 11. Laryngeal Mask Airway. Conclusion Laryngeal Mask Airway (LMA TM, LMA North America, Inc., San Diego, CA) Fig. 11은성문외기구로서환기의통로를제공하며실패한기도에서중요한역할을한다. 7 기관내삽관에비해서삽입이쉽고간편하며, 비숙련자라할지라도쉽게사용할수있다. 28,29 하지만밀봉이완벽하지않으며, 흡인으로부터기도를보호할수없는점이단점으로 1차적인기술보다는구난기술로서만사용하여야한다. 또한 LMA를통하여기관내삽관을할수있도록고안된 LMA도있다. 이러한장비들을모두다익히는것보다는하나라도평소에연습하여실전에서기관내삽관이어려울때사용할수있도록익숙해지는것이좋다. 중환자실에서의기관내삽관은수술실에서의기관내삽관보다어려운경우가많고, 합병증또한많다. 또한기관내삽관이언제라도필요할수있으므로, 입원시에기도에대한평가를하여야만응급상황에서기도관리계획을세우는데도움이된다. 먼저기관내삽관이필요한지를결정한후, 기관내삽관이필요하다면, 기도관리의알고리즘에따라서기관내삽관을시도하며, 특별한금기증이없다면 RSI를통하여기관내삽관을시도한다. 기관내삽관이실패할경우를대비하여, Plan B로서 Gum elastic bougie, video laryngoscope, LMA 등을미리준비하고있어야하며, 평소에하나라도잘사용할수있도록익숙해져야한다. 기관내삽관이 3번이상실패하거나산소화에실패하면 Plan C로서지체없이 Cricothyroidotomy를시행하도록한다. www.surgicalcriticalcare.org 37
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