세부전문학회발표 소아기도관리의최신지견 연세대학교의과대학마취통증의학교실 이정림 소아의호흡기계는해부학적으로나생리학적으로성인과는많은차이가있으며, 따라서소아의기도관리는소아마취에서핵심적이고중요한부분을차지한다. 이강의에서는소아기도관리와관련해서최근에논란이되고있는부분들과새로운의견들에대해소개하고자한다. 소아후두의해부학 : 깔때기모양 vs. 원통모양 Eckenhoff가 1951년영아와소아상기도해부결과를발표한이후로 [1], 소아의후두는깔때기모양이고가장좁은부분이윤상연골부위라는것은마취과의사들의오랜믿음이었다. 그러나, 최근의연구들은소아의후두도성인과마찬가지로원통형태라는결과를제시하고있다. Litman은 0 14세의소아 91명의상기도 MRI소견을분석하였는데, 그결과성장과관계없이모든연령대의소아후두에서의가장좁은부위는윤상연골이아닌성문과성문바로아래부위이고, 후두는 transverse 단면으로는 cone모양, A-P 단면으로는원통모양이었다 [2]. Dalal 등은비디오기관지경 (video-bronchoscope) 을이용하여 6개월 13세의소아의상기도를관찰하였는데, 그결과도 Litman과유사하였다. 또한, Dalal 등은소아의윤상연골부위는단면이원이아니라타원형태라고하였다 [3]. 이와같은연구결과들이소아에서의기관내관의선택에있어서어떤임상적인의미를지니는지에대해서는향후고찰이필요할것이다. 소아에서의기관내관의선택 : 기낭이없는내관 vs. 기낭이있는내관전통적으로 8세이하의소아에서는기낭이없는기관내관이선호되었다. 이는소아의후두에서가장좁은부위는윤상연골이라는지식을기반으로기낭의압력으로인한기도점막의허혈을최소하하고기낭이있는튜브에비해더큰외경 ( 즉, 내경 ) 의튜브를선택할수있다는장점이있었기때문이었다. 소아에서기낭이있는튜브와없는튜브에대한비교연 구는 1997년 Khine 등이처음발표되었다. 그결과, 기낭이있는튜브가기낭이없는튜브에비해재삽관의빈도가훨씬낮았고 (1.2% vs. 23%) 신선가스유량을 2 L/min 이상을사용한경우도유의하게적었다 (1.2% vs. 11%). 또한, 후두염증상 (croup) 으로측정한기도관련부작용은두군간에차이가없었다 [4]. Khine의이연구이후로최근의연구결과들은소아에서의기낭없는튜브의사용이필수적인가에이의를제기하고있다. 이에따르면기낭이있는튜브는재삽관의빈도를낮추고, 흡인을예방하고, 최신인공호흡기들의다앙한기능들을사용할수있게해주며, 폐의유순도가떨어진소아에서도적절한압력의호흡을제공할수있다는등의장점이있다 [5]. 그러나, 기낭이있는튜브가소아마취에서 routine으로안전하게사용되기위해서는기낭의크기와길이, 기낭의재질, 적절한깊이표시 (depth mark) 등제조적인측면에서개선이필요하고, 근거에중심한적절한크기선택의기준등에대한정보가충분히축적되어야할것이다 [6]. 기관내삽관기구어려운삽관을위해고안된기구들은대개성인의상기도구조를기준으로개발되며, 이것의크기를줄여소아에게적용하는것이일반적이다. 따라서이미성인에서유용성이입증된기구라하더라도소아에서는유용성을알수없거나오히려유용하지않은기구들도있을수있다. 광학 (Optical) stylet 소아에서사용이가능한광학 stylet으로는 Shikani optical stylet과 Bonfils endoscope가있다. Shikani는 stylet의끝이구부러지도록만들어진반면, Bonfils은 40도정도의곡선으로굽어진딱딱한 stylet이다. Shikani optical stylet은삽관이어려울것으로예상되는소아에서의유용성에대한증례보고들이있다 [7-9]. Bonfils fiberscope은일부기도삽관이어려운소아에서유용하게사용되었다고하나 [10-11], Bain 등은정상기도를가진소아에서는성공률이낮고삽관시간은오래걸려서장점이없는기구라고주장하였다 [12]. 대한소아마취학회 239
광학후두경소아에서사용할수있는크기가구비된기구로는 Glide- Scope, Storz video laryngoscope, Airtraq optical laryngoscope 등이있다. 일반적으로후두경을손쉽게사용하는마취과의사입장에서는광학후두경은추가적인기술습득없이사용할수있는장점이있으나, 소아에서사용시에는몇가지제한점이있으며, 그중하나는이들은 blade의크기가비교적커서개구정도가충분한소아에서사용이용이하다는점이다. GlideScope은정상기도를가진소아나삽관이어려운소아모두에서기존의후두경을대치하거나더나은선택이될수있다는결과들이보고되었다 [13-16]. 최근에나온 GlideScope-Cobalt는날이더얇고앞쪽끝이더구부러져서있으며, 영아용 blade 추가되어더욱유용하게사용할수있을것으로기대되지만, 아직이에대한충분한임상결과는부족하다 [17]. Storz videolaryngoscope은정상기도를가진소아에서는일반후두경에비해 laryngeal view를개선시킨다고하나 [18] 어려운기도를가진소아를대상으로된연구는부족하다. Airtraq는상기도의해부학적기형이있는증후군의소아에서유용하게사용하였다는증례보고는있으나 [19-21] 다른기구와의비교임상연구는아직없다. 후두마스크 (Laryngeal mask airway, LMA) 사용과관련된새로운견해 LMA는이미소아에서도기관삽관과마스크호흡과비슷한비중을차지할정도로중요한기도유지방법이다. 그러나소아의 LMA는성인의것을크기만축소해서만들었기때문에기도의구조가성인과는다른소아에서대중적으로사용되기까지는많은경험이필요하였고, 최적의사용을위한연구가아직도계속되고있다. 삽입방법소아의상기도구조는성인과달라서소아에서의 LMA 삽입은성인에비해쉽지않으며, 전통적인 Brain의방법으로삽입시성공률은 67 90% 로알려져있다. 이를극복하기위해 90도회전하는방법 (lateral technique) 과 180도회전하는방법 (rotation technique) 이고안되었다. Chai 등은 180도회전하는방법이최초삽입시성공률이 96% 로 90도회전방법의 84%, 전통적인방법의 80% 에비해월등히높고, 삽입에걸리는시간과기도외상, 후두경련등합병증의빈도도낮다고하였다 [22]. 적절한기낭압력기낭압력은 pharyngeal morbidity와 pharyngeal sealing을결정하는요소이다. 기낭에공기를주입했을때 LMA가살짝밀려나오면이를적절한기낭압이라고생각했던기존의임상기준을적용할경우, 소아에서는기낭의압력을 92 cmh 2O에서 120 cmh 2O까지높이며, 이로인해구인두로의공기의누출은기낭압력이 60 cmh 2O일때보다증가한다고한다 [23]. 또한, 제조사에서권장하고있는기낭공기량을그대로적용할경우도기낭의압력을권장수준이상으로높인다고하였다. Von Ungern-Sternberg 등은다양한크기와종류의 LMA에서, 포장에서처음개봉시기낭에들어있던공기량만으로 ballooning을하고압력을측정하였는데, 이때도기낭의압력이 60 cmh 2O를넘는경우가 20.5% 에이르렀고, 크기가작은 LMA나표면이 PVC로된 1회용 LMA에서는그빈도와정도가더심했다 [24]. 따라서기낭을약간부풀린채로 LMA를삽입할때, 삽입후에는기낭에공기를오히려약간제거하는것이필요하다고주장하였다. Hoking 등은최근지금까지의기준인 60 cmh 2O에비해 40cmH 2O로기낭의압력을맞추는것이공기누출을줄이고 sealing은좋게한다는연구결과를발표하였다 [25]. 후두마스크이외의성문위기도유지기구 (Supraglottic airway device) 의소아에서의유용성현재소아에서사용가능한성문위기도유지기구는 LMA 이외에도 flexible LMA, LMA-Proseal, PVC 재질로된 1회용 LMA, CobraPLA, Laryngeal tube, i-gel 등이있다. CobraPLA는 1회용 LMA와비교하여삽입의용이성과 complication에는차이가없고, 구인두로의공기누출압 (oropharyngeal leak pressure) 은 LMA와같거나오히려높아위로의공기주입 (gastric insufflation) 의정도가적고, 마취중더안정적으로거치된다고한다 [26,27]. LMA-Proseal은 2세대 LMA로서, 적절하고안정적인해부학적거치, 구인두누출압 (oropharyngeal leak pressure) 등의측면에서 LMA보다나은결과를보였다 [28,29]. LMA-Proceal 은복강경수술에서도기관내관과유사하게효과적으로환기를유지할수있다는보고도있다 [30]. i-gel은가장최근에개발된성문위기도유지기이며, 소아에사용할수있는크기의제품은 2009년출시되어소아용크기의 i-gel에대해서는아직출판된연구결과가없다. 무엇보다도 i-gel은단면이타원으로되어있어마취중에보다안정적으로거치된다고알려져있는데, 이러한특징이 10 kg 이하의소아에서기존의 LMA가가지고있는문제점을 240
이정림 : 소아기도관리의최신지견 보완할수있을지기대된다 Laryngeal Tube는 LMA에비해삽입방법이쉽고기구의머리부분이 LMA보다작아서개구정도가작거나편도가큰소아에서장점을가질수있을것이다. 그러나머리와목의자세변화에따라호흡의효율이떨어지는단점이있고, LMA에비해더유용한지에대해서는더많은임상경험이있어야할것이다 [31,32]. 참고문헌 1. Eckenhoff JE. Some anatomic considerations of the infant larynx influencing endotracheal anesthesia. Anesthesiology 1951; 12: 401-10. 2. Litman RS, Weissend EE, Shibata D, Westesson P-L. Developmental change of laryngeal dimensions in unparalyzed, sedated children. Anesthesiology 2003; 98: 41-5. 3. Dalal PG, Murray D, Messner AH, Feng A, McAllister J, Molter D. Pediatric laryngeal dimensions: an age-based analysis. Anesth Analg 2009; 108: 1475-9. 4. Khine HH, Corddry DH, Kettrick RG, Martin TM, McCloskey JJ, Rose JB, Theroux MC, Zagnoev M. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology 1997; 86: 627-31. 5. Weber T, Salvi N, Orliaguet G, Wolf A. Pro-con debate: Cuffed vs non-cuffed endotracheal tubes for pediatric anesthesia. 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Szmuk P, Ghelber O, Matuszczak M, Rabb MF, Ezri T, Sessler DI. A prospective, randomized comparison of cobra perilaryngeal airway and laryngeal mask airway unique in pediatric patients. Anesth Analg 2008; 107: 1523-30. 27. Gaitini L, Carmi N, Yanovski B, Tome R, Resnikov I, Gankin I, Somri M, Alfery D. Comparison of the CobraPLA (Cobra Perilaryngeal Airway) and the Laryngeal Mask Airway Unique in children under pressure controlled ventilation. Paediatr Anaesth 2008; 18: 313-9. 28. Lopez-Gil M, Brimacombe J, Garcia G. A randomized noncrossover study comparing the ProSeal and Classic laryngeal mask airway in anaesthetized children. Br J Anaesth 2005; 95: 827-30. 대한소아마취학회 241
29. Lardner DR, Cox RG, Ewen A, Dickinson D. Comparison of laryngeal mask airway (LMA)- Proseal and the LMA-Classic in ventilated children receiving neuromuscular blockade. Can J Anaesth 2008; 55: 29-35. 30. Sinha A, Sharma B, Sood J. ProSeal as an alternative to endotracheal intubation in pediatric laparoscopy. Paediatr Anaesth 2007; 17: 327-32. 31. Genzwuerker HV, Fritz A, Hinkelbein J, Finteis T, Schlaefer A, Schaeffer M, Thil E, Rapp HJ. Prospective, randomized comparison of laryngeal tube and laryngeal mask airway in pediatric patients. Paediatr Anaesth 2006 D; 16: 1251-6. 32. Kaya G, Koyuncu O, Turan N, Turan A. Comparison of the laryngeal mask (LMA) and laryngeal tube (LT) with the perilaryngeal airway (cobrapla) in brief paediatric surgical procedures. Anaesth Intensive Care 2008; 36: 425-30. 242
세부전문학회발표 Laryngospasm in children: update on pathophysiology and management 동아대학교의과대학마취통증의학교실 최소론 Introduction Laryngospasm - Reflex closure of the upper airway as a result of the glottic musculature spasm - Protective reflex that acts to prevent foreign material entering the tracheobronchial tree Complete glottic closure - May lead to hypoxia and hypercapnea - In majority of patients, the problem is self-limited - In certain cases, the spasm is sustained Sustained spasm - Morbidity such as cardiac arrest, arrhythmia, pulmonary edema, bronchospasm or gastric aspiration may occur Complete laryngospasm - Chest movement but silent with no bag movement and no ventilation possible. Partial laryngospasm - Chest movement but stridulous noise with a mismatch between the patients respiratory effort and the small amount of bag movement. Incidence Overall incidence - 0.87% Children in the first 9 years of age - 1.74% Infants between 1 to 3 months - 2.82% Incidence of morbidity resulting from laryngospasm - Cardiac arrest 0.5% - Postobstructive negative pressure pulmonary edema 4% - Pulmonary aspiration 3% - Bradycardia 6% - Oxygen desaturation 61% Mechanism - Elicited by stimulation of the afferent fibers contained in the internal branch of the superior laryngeal nerve. - These reflexes control the laryngeal muscle contractions which protect the airway during swallowing. Laryngospasm may occur secondary to loss of inhibition of the laryngeal closure reflex as a result of abnormal excitation. Cause - Laryngospasm occurs during anesthesia for two reasons : firstly, a lack of inhibition of glottic reflexes because of inadequate central nervous system depression and, secondly increased stimuli. Causes of stimulation at an inappropriate depth of anesthesia - Extubation, secretions or blood irritating the vocal cords, stimulation of the airway by an artificial airway, laryngoscope or suction catheter. Recognition - Identified by varying degrees of airway obstruction with paradoxical chest movement, intercostal recession and tracheal tug. A characteristic crowing noise may be heard in partial laryngospasm but will be absent in complete laryngospasm. Risk factors - Anesthesia-related Light level of anesthesia, vocal cord irritation, inexperience 대한소아마취학회 243
of anesthesiologist, multiple endotracheal intubations and LMA insertion - Patient-related Young age, URI, passive smokers and children with hyperactive airway - Surgery-related Airway procedures Prevention Prevention in preoperative phase - Detailed history: smoking, URI and past history Prevention during induction phase - Experienced anesthesiologist, continuous monitoring of respiratory sounds, anesthetic agent, muscle relaxants and 2% lidocaine gel Prevention during maintenance phase - Uncuffed ETT, cuff with water and continuous monitoring of cuff pressure Prevention in emergence phase - Deep or awake (controversy) Prevention using drugs - Lidocaine, cocaine and magnesium 100% oxygen. Treatment using drugs - Propofol - Succynylcholine with atropine Treatment using other drugs - Alfentanil, meperidine, diazepam, doxapram and nitroglycerine Treatment of refractory laryngospasm Postlaryngospasm follow-up - Humidified oxygen - Close obsevation Conclusions Identifying the risk factors and taking the necessary precautions are key points in preventing laryngospasm. To overall decrease the risk of laryngospasm, anesthesia should be carried out by experienced anesthesiologist. Regarding management, in most cases, airway maneuver by an experienced anesthesiologist usually treats laryngospasm. However, drug administration may be needed to break the spasm especially in junior anesthesiologists. References Treatment Treatment success mainly depends on the experience of the anesthesia provider. Treatment with airway management - Opening the mouth, tight sealing with facemask, extending neck with jaw lift and applying CPAP ventilation with 1. Alalami AA, Ayoub CM, Baraka AS. Laryngospasm: review of different prevention and treatment modalities. Paediatr Anaesth 2008; 18: 281-8. 2. Hampson-Evans D, Morgan P, Farrar M. Pediatric laryngospasm. Paediatr Anaesth 2008; 18: 303-7. 3. Al-alami AA, Zestos MM, Baraka AS. Pediatric laryngospasm: prevention and treatment. Curr Opin Anaesthesiol 2009; 22: 388-95. 244