Original article http://dx.doi.org/10.22470/pemj.2016.3.2.48 pissn: 2383-4897 / eissn: 2508-5506 소아응급실에서케타민근육주사를이용한진정시호기말이산화탄소분압감시의유용성 양형준 서효연 곽재령 이지숙 아주대학교의과대학응급의학교실 Utility of end-tidal carbon dioxide monitoring in intramuscular ketamine sedation in the pediatric emergency department Hyung Jun Yang, Hyo Yeon Seo, Jae Ryoung Kwak, Ji Sook Lee Department of Emergency Medicine, Ajou University School of Medicine, Suwon, Korea Purpose: Recently, the use of end-tidal carbon dioxide (ETCO 2) monitoring has been suggested for early detection of hypoventilation over oxygen saturation (S PO 2) monitoring. We aimed to determine the usefulness of capnography in monitoring patients sedated using intramuscular (IM) ketamine in the pediatric emergency department (ED). Methods: This study retrospectively reviewed medical records of patients younger than 16 years who were sedated using IM ketamine and whose ETCO 2 values were documented in the ED. Age, sex, American Society of Anesthesiologists physical status classification (ASA classification), and purpose of sedation were investigated. Vital signs were recorded at pre-sedation, 5 and 10 minutes after sedation, and after recovery. Hypoventilation was defined as S PO 2 < 95%, ETCO 2 50 mmhg or 30 mmhg, or increase in ETCO 2 10 mmhg from the baseline without tachypnea. Results: A total of 49 patients were investigated; 42 of them belonged to ASA classification I, and 7 to II. There was no patient with S PO 2 < 95%, or ETCO 2 50 mmhg, or increase in ETCO 2 10 mmhg from the pre-sedation value. However, 5 patients had an ETCO 2 30 mmhg, and 4 of them (8.2%) had normal respiratory rate and were suitable for hypopneic hypoventilation. Ten patients showed abnormal range of ETCO 2 (normal range, 35-45 mmhg), but did not meet the definition of hypoventilation. No one had clinically serious respiratory events. Conclusion: During sedation using IM ketamine, 8.2% of the patients had hypopneic hypoventilation without hypoxemia, and they were all younger than 36 months. Capnography for patients sedated using IM ketamine in the ED is useful in detecting hypopneic hypoventilation, and has the potential for preventing clinically serious respiratory events in patients, especially toddlers. Key words: Capnography; Conscious Sedation; Hypoventilation; Ketamine; Pediatrics Received: Oct 1, 2016 Revised: Oct 1, 2016 Accepted: Oct 5, 2016 서 론 Corresponding author Ji Sook Lee Department of Emergency Medicine, Ajou University School of Medicine, 164 World cup-ro, Yeongtong-gu, Suwon 16499, Korea Tel: +82-31-219-7756 Fax: +82-31-219-7760 E-mail: eesysook@naver.com 협조가되지않는소아응급환자에게적절한검사및응급처치를시행하기위해진정제를투여하는경우가많다. 진정제는심각한호흡계및심혈관계부작용을초래할수있는데, 이러한부작용을예방하기위해서는진정후활력 48
케타민진정 ETCO 2 감시 징후를감시하는것이중요하다. 응급실에서는환자수보다의료자원이상대적으로부족하므로, 진정단계에따른효율적인감시장치의선택이중요하다. 응급실에서권장되는진정단계는중등도진정, 즉언어자극에목적있는반응을보이는단계이다. 이단계를달성하고유지하기위해서는지속적인산소포화도및심장박동수감시와간헐적인호흡수및혈압측정이필요하다 1). 케타민은응급실에서흔히사용되는진정제로호흡계안정성이장점이지만, 소수에서저산소증및성문연축등의부작용이보고되고있다. 호기말이산화탄소분압 (endtidal carbon dioxide, ETCO 2) 감시가기존의산소포화도및심장박동수보다조기에저환기를감지할수있다는장점이대두하면서, 응급실에서진정시 ETCO 2 감시의필요성이제시되고있다 1-4). 기존의 ETCO 2 감시는기관내삽관을전제로가능하였지만, 최근에는코와입에거치하는도관을이용한모델이상용화되었다. 국내에서는소아응급환자진정시 ETCO 2 감시가아직활성화되지못한실정이며, 관련된경험을보고한연구는없었다. 이에케타민근육주사를이용하여진정을시행한소아응급환자에서 ETCO 2 감시가저환기를효과적으로감지할수있는지를분석하고자하였다. 대상과방법 본연구는 2015년 3월부터 8월까지아주대학교병원권역응급의료센터를방문한 15세이하소아응급환자의의무기록에기초한후향적연구이며, 아주대학교병원기관연구윤리심의위원회의승인을받고시행하였다 (IRB No: AJIRB-MED-MDB-16-428). 연구대상은연구기간동안본원응급실에서케타민근육주사 (4 mg/kg, 1회 ) 를이용한진정을시행받은환자중, ETCO 2 감시가이루어지고진정기록지가형식에맞게작성된환자였다. 케타민을 2회이상투여한경우및호흡기질환환자는분석에서제외하였다. 의무기록을검토하여성별, 나이, 미국마취과학회 (American Society of Anesthesiologists, ASA) 분류, 진정목적을조사하였다. 진정기록지를통해네시점 ( 진정전, 진정 5분및 10분후, 회복후 ) 의활력징후 ( 호흡수, 심장박동수, 산소포화도, ETCO 2) 를조사하였다. 진정후발생하는저환기는, 진정후산소포화도가 95% 미만으로감소한경우, ETCO 2 가 30 mmhg 이하로감소하거나 50 mmhg 이상으로증가한경우, 진정전보다 ETCO 2 가10 mmhg 이상증가한경우로정의하였다 5,6). 저환기를세분 화하여, 호흡수감소에따라 ETCO 2 가증가하는경우는느린호흡성저환기 (bradypneic hypoventilation) 로, 호흡수가정상또는증가하고일회호흡량이감소하여 ETCO 2 가감소하는경우는호흡저하성저환기 (hypopneic hypoventilation) 로각각정의하였다. 단, ETCO 2 감소와함께나이에비하여빈호흡을보인경우는, 과환기에의해 ETCO 2 가감소한것으로보고저환기에포함하지않았다. 저환기발생시, 가벼운자극, 기도조작, 산소투여또는양압환기등응급처치시행여부에대해서도조사하였다. ETCO 2 감시에는이동형 Nellcor NPB-70 (Nellcor Puritan Bennett Inc., Pleasanton, CA) 을사용하였다. 이장비는환자의코와입을통해 ETCO 2 를측정할수있어, 기관내삽관이시행되지않은환자에게도적용할수있다. 연속형변수는평균및표준편차로, 범주형변수는빈도및분율로각각표시하였고, 모든분석에는 SPSS ver. 16.0 (SPSS Inc, Chicago, IL, USA) 을사용하였다. 결과 총 49명의환자가연구대상에포함되었다. 평균나이는 3.0 ± 2.0세였고, 이중남자가 33명 (67.3%) 이었다. 42 명이 ASA 1단계, 7명이 2단계에해당하였고, 진정목적은모두안면열상이었다. 진정전평균호흡수는 27.8 ± 6.5회 / 분, 맥박수 127.4 ± 22.1회 / 분, ETCO 2 는 37.8 ± 3.5 mmhg였으며, 산소포화도는모든환자에서 98% 이상이었다. 호흡수를진정전후시점에따라비교한결과, 호흡수변화의폭이다양하였다 (Fig. 1). 저환기발생빈도에대해분석한결과, ETCO 2 가 50 mmhg 이상으로증가하거나진정전보다 10 mmhg 이상증가한환자는없었다. 반면 5명의환자 ( 모두 36개월이하 ) 의 ETCO 2 가 30 mmhg 이하로감소하였다. 이중 4명 (8.2%) 의호흡수는나이에따른정상범위를보였으므로 7), 호흡저하성저환기로분류되었다. 반면, 분당 62회로빈호흡을보인 1명은과환기에의해 ETCO 2 가감소한것으로보고, 저환기에서제외하였다. 호흡저하성저환기를보인4명의환자중3명은진정5분후, 1명은10분후 ETCO 2 가 30 mmhg 이하로감소하였다 (Table 1). 진정 5분후 ETCO 2 가 23 mmhg으로저하되었던 17개월환자에게는가벼운자극을준결과, 진정 10분후 ETCO 2 는 44 mmhg로증가하였다. 진정 10분후 ETCO 2 가 29 mmhg로감소하였던환자를포함한나머지 3명에게도별다른응급처치가시행되지않았으며, 이후 ETCO 2 및산소포화도는모두정상범위로회복되었다. Pediatric Emergency Medicine Journal 49
Pediatr Emerg Med J 2016;3(2):48-52 Fig. 1. The variation of respiratory rates before and after sedation using intramuscular ketamine. Each dot represents an individual patient s respiratory rate measured at 4 time points: pre-sedation, 5 and 10 minutes after sedation, and after recovery. Table 1. A comparison of respiratory parameters in four patients with hypopneic hypoventilation* Patient Age (mo) RR (/min) ETCO 2 (mmhg) S PO 2 (%) 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd A 12 32 25 24 32 27 37 100 100 100 B 12 30 25 34 28 30 38 099 099 100 C 17 23 22 63 34 23 44 099 099 100 D 36 25 24 24 32 40 29 100 100 100 * Hypopneic hypoventilation refers to the case of ETCO 2 30 mmhg without tachypnea. 1st indicates the measurement taken before sedation. 2nd indicates the measurement taken 5 minutes after sedation. 3rd indicates the measurement taken 10 minutes after sedation. RR: respiratory rate, ETCO 2: end-tidal carbon dioxide, S PO 2: oxyhemoglobin saturation measured by pulse oximeter. 저환기의정의에해당하지않지만 ETCO 2 가정상범위 (35-45 mmhg) 를벗어나는환자를조사한결과, 49명의환자에서진정 5분및 10분후에시행된총 98건의측정중, 10명에서확인된 12건이이에해당하였다. 이중 ETCO 2 가 31-34 mmhg로감소한경우가 10건, 46-49 mmhg로증가한경우가 2건이었지만, 12건모두정상호흡수를보였다. 고찰 본연구는케타민근육주사를이용하여진정을시행한 소아응급환자에서발생하는저환기에대한 ETCO 2 감시의유용성에관한국내첫보고이다. 케타민은소아응급환자의진정및진통에안전하고효과적인약물로사용되었다. 케타민이유도하는해리성진정의중요한특징은호흡수및일회호흡량과같은기본적인호흡지표가안정적으로유지된다는점이다 8). 케타민투여후호흡계부작용은 1.4%-3.9% 에서발생한다고알려져있으며, 이중성문연축및무호흡과같은심각한호흡계부작용은 1% 이내로보고되었다 9,10). 본연구에서는케타민진정후심각한호흡계부작용은발생하지않았으며, 저환기를보인환자중응급처치 ( 가벼운자극 ) 를시행받은환자는 1명이었다. 50 Pediatric Emergency Medicine Journal
케타민진정 ETCO 2 감시 진정후발생하는저환기는크게두가지유형으로나눌수가있다 (Fig. 2) 5,6). 첫번째는느린호흡성저환기로, 호흡수감소에따라 ETCO 2 가증가하는유형이다. 이유형의저환기는호흡수가감소하면서일회호흡량은증가하는양상을보이므로, 호기말이산화탄소분압측정그래프에서 ETCO 2 측정값은증가하고호기시간이길어지므로일회호흡에따른그래프의폭이넓어진다. 마약성진통제투여후흔히관찰된다. 두번째는호흡저하성저환기로, 호흡수는정상또는증가하고일회호흡량이감소하여, ETCO 2 에사강에있는호흡량이상대적으로많이반영되는유형이다. 호기말이산화탄소분압측정그래프에서 ETCO 2 측정값은감소하고호기시간이짧아지므로일회호흡에따른그래프의폭이좁아진다. 진정제투여후흔히관찰된다. 느린호흡성저환기는흉곽의움직임또는호흡수의감소를통해발견할수있지만, 호흡저하성저환기는호흡수감소가현저하지않기때문에 ETCO 2 감시없이발견하기어렵다. 저환기의유형에관계없이, 초기 2-3분간산소포화도가정상범위로유지될수있다 6,11). 따라서 ETCO 2 감시는저환기를조기에발견하는데더욱민감하고유용하다. 케타민, 미다졸람, 펜타닐, 프로포폴등다양한진정제를투여한후발생하는저환기에관한많은연구가발표되었다 2,12,13). 기존에는호흡수및산소포화도를지표로삼았으며, ETCO 2 를측정한경우에도측정값의상승에중점을두고저환기여부를평가하였다. 그결과대다수는느린호흡성저환기에해당하는보고들이었다. 반면, 케타민단독또는케타민과미다졸람을함께투여하여진정후 ETCO 2 감시를시행했던다른연구에서는, 호흡저하성저환기가 50% 에서발생하였음을보고하였다 6). 본연구에서호흡저 하성저환기의발생빈도가낮게나타난것은, 케타민단독으로투여한진정이라는점에기인했을수있다. 저환기가발생한환자의나이는모두 36개월이하였다. 이전에나이에따른호흡저하성저환기발생빈도의차이를보고한연구가없었다는점을고려하면, 본연구를통하여나이가어릴수록케타민진정후호흡저하성저환기의발생빈도가증가한다는가설을유도할수있다. 본연구에서케타민진정후심각한호흡계부작용은발생하지않았다. 이전연구에서도 ETCO 2 감시를하는경우에기도조작또는가벼운자극과같은응급처치의빈도는증가하지만저산소증이발생하는빈도는증가하지않는것으로나타났다 4,14,15). 2016년현재국내에서는수술실에서마취를시행하는모든환자에게 ETCO 2 감시를시행하고있지만, 의료자원이부족한응급실에서진정시 ETCO 2 감시를일괄적으로시행하기는어려운실정이다. 그러나 ETCO 2 는저환기의가장민감한지표이므로, 호흡저하성저환기의위험성이높은 36개월이하환자에게선택적으로적용하는것은필요하다. 본연구에서는후향적연구설계로인하여, 진정기록지에작성된 ETCO 2 가정상범위에서벗어난경우, 그지속시간을알수없었다. 단, 응급처치또는저산소증에관한기록이없는경우, 저환기가일과성으로발생한것으로간주하였다. 저자의경험에의하면, 케타민진정후 ETCO 2 를지속적으로감시할경우호흡수변화에따라수초간격으로 ETCO 2 변화가나타나는경우가많았다. 추후전향적연구를통하여, 저환기의지속시간이나호흡패턴의변화에대한추가적인분석이필요하다. 본연구를통하여, 케타민근육주사를이용하여진정을 A B Fig. 2. Capnograms indicating two types of hypoventilation. The waveform in (A) denotes increased amplitude (i.e., end-tidal carbon dioxide) and width (i.e., exhalation time) with decreasing respiratory rate, representing bradypneic hypoventilation. The waveform in (B) denotes decreased amplitude and exhalation time with normal or increasing respiratory rate, representing hypopneic hypoventilation. Pediatric Emergency Medicine Journal 51
Pediatr Emerg Med J 2016;3(2):48-52 시행한소아환자에서저환기발생을조기에발견하는데 ETCO 2 감시가유용함을확인하였다. 심각한호흡계부작용은발생하지않았지만, 36개월이하환자에서는호흡저 하성저환기가자주발생하는경향을보였다. 따라서 36 개월이하환자에서는 ETCO 2 감시를적극적으로고려할필요가있다. References 01. Godwin SA, Burton JH, Gerardo CJ, Hatten BW, Mace SE, Silvers SM, et al. Clinical policy: procedural sedation and analgesia in the emergency department. Ann Emerg Med 2014;63:247-58.e18. 02. Yldzdas D, Yapcoglu H, Ylmaz HL. The value of capnography during sedation or sedation/analgesia in pediatric minor procedures. Pediatr Emerg Care 2004;20: 162-5. 03. Conway A, Douglas C, Sutherland J. Capnography monitoring during procedural sedation and analgesia: a systematic review protocol. Syst Rev 2015;4:92. 04. Langhan ML, Shabanova V, Li FY, Bernstein SL, Shapiro ED. A randomized controlled trial of capnography during sedation in a pediatric emergency setting. Am J Emerg Med 2015;33:25-30. 05. Krauss B, Hess DR. Capnography for procedural sedation and analgesia in the emergency department. Ann Emerg Med 2007;50:172-81. 06. Langhan ML, Chen L, Marshall C, Santucci KA. Detection of hypoventilation by capnography and its association with hypoxia in children undergoing sedation with ketamine. Pediatr Emerg Care 2011;27:394-7. 07. Fleming S, Thompson M, Stevens R, Heneghan C, Pluddemann A, Maconochie I, et al. Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies. Lancet 2011;377:1011-8. 08. Kim G, Green SM, Denmark TK, Krauss B. Ventilatory response during dissociative sedation in children-a pilot study. Acad Emerg Med 2003;10:140-5. 09. Green SM, Kuppermann N, Rothrock SG, Hummel CB, Ho M. Predictors of adverse events with intramuscular ketamine sedation in children. Ann Emerg Med 2000;35: 35-42. 10. Green SM, Roback MG, Krauss B, Brown L, McGlone RG, Agrawal D, et al. Predictors of airway and respiratory adverse events with ketamine sedation in the emergency department: an individual-patient data meta-analysis of 8,282 children. Ann Emerg Med 2009;54:158-68.e1-4. 11. Verhoeff F, Sykes MK. Delayed detection of hypoxic events by pulse oximeters: computer simulations. Anaesthesia 1990;45:103-9. 12. McQuillen KK, Steele DW. Capnography during sedation/ analgesia in the pediatric emergency department. Pediatr Emerg Care 2000;16:401-4. 13. Tobias JD. End-tidal carbon dioxide monitoring during sedation with a combination of midazolam and ketamine for children undergoing painful, invasive procedures. Pediatr Emerg Care 1999;15:173-5. 14. Campbell SG, Magee KD, Zed PJ, Froese P, Etsell G, LaPierre A, et al. End-tidal capnometry during emergency department procedural sedation and analgesia: a randomized, controlled study. World J Emerg Med 2016;7:13-8. 15. Green SM, Pershad J. Should capnographic monitoring be standard practice during emergency department procedural sedation and analgesia? Pro and con. Ann Emerg Med 2010;55:265-7. 52 Pediatric Emergency Medicine Journal