Anesth Pain Med 2018;13:447-453 https://doi.org/10.17085/apm.2018.13.4.447 pissn 1975-5171 ㆍ eissn 2383-7977 임상연구 10 분수술전가온이주술기저체온예방에미치는효과 : 30 분수술전가온과의비교연구 유재화ㆍ옥시영ㆍ김상호ㆍ박선영ㆍ한유미ㆍ김도연 순천향대학교의과대학서울병원마취통증의학교실 Received April 19, 2018 Revised 1st, May 31, 2018 2nd, June 8, 2018 Accepted June 12, 2018 The effect of 10 minutes of prewarming for prevention of inadvertent perioperative hypothermia: comparison with 30 minutes of prewarming Jae Hwa Yoo, Si Young Ok, Sang Ho Kim, Sun Young Park, Yoo-mi Han, and Doyeon Kim Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea Corresponding author Si Young Ok, M.D., Ph.D. Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesagwan-ro, Yongsan-gu, Seoul 04401, Korea Tel: 82-2-709-9302 Fax: 82-2-790-0394 E-mail: syok2377@naver.com ORCID http://orcid.org/0000-0001-7572-5311 Background: At least 30 minutes of pre-warming has been recommended for the prevention of redistribution hypothermia. However, it has been reported that less than 30 minutes of pre-warming is also effective. The aim of this study was to evaluate the ability of 10 minutes of pre-warming to prevent inadvertent perioperative hypothermia. Results were compared with 30 minutes of pre-warming. Methods: In this prospective randomized study, 59 patients scheduled for elective surgery less than 120 minutes under general anesthesia were divided into 2 groups: the first group was pre-warmed for 10 minutes (n = 30), the second group for 30 minutes (n = 29). The patients were pre-warmed for 10 or 30 minutes in the pre-anesthetic area using a forced-air warmer. When the patients body temperatures decreased below 36 C, we warmed them with a forced-air warmer intraoperatively and postoperatively. Body temperatures were recorded during perioperative periods. Shivering and thermal comfort were evaluated in the pre-anesthetic area and post-anesthesia care unit. Results: The incidence of intraoperative and postoperative hypothermia were not significantly different (P > 0.05). However, the temperatures were higher in the 30 minute group from the post-warming time to 90 minutes after anesthetic induction (P < 0.05). Conclusions: Ten minutes of pre-warming has the same effectiveness as 30 minutes of pre-warming for preventing inadvertent perioperative hypothermia. It is a preferable choice for the patients scheduled for surgery less than 120 minutes under general anesthesia. Keywords: Forced-air warming; Perioperative hypothermia; Preoperative warming. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright c the Korean Society of Anesthesiologists, 2018 447
Anesth Pain Med Vol. 13 No. 4 서론 주술기저체온은주술기간에체온이의도치않게 36 C 미만으로감소되는것으로정의되며, 간단한수술이라도 50 90% 까지흔하게나타난다 [1,2]. 주술기저체온은수술후떨림 [3], 열불쾌감 [4] 뿐만아니라심장부정맥과심근허혈을포함한심장이환 [5], 약물대사의저하 [6], 마취회복지연 [7], 혈소판및응고기전의기능저하와연관된실혈량의증가 [8], 상처회복지연과수술부위감염 [9] 등과연관되어있어반드시예방하기위한노력이필요하다. 그러나아직까지도체온유지를위한감시및노력이부족한현실이다 [10]. 주술기저체온은마취유도직후부터빠르게나타나며, 특히마취첫 1시간에는 1.6 C 의중심체온감소를보이고이중마취제로유도된혈관확장에의한중심-말초온도재분포가미치는영향이 81% 를차지하며, 46 kcal의열이재분포된다고알려져있다 [11]. 이런재분포로인한저체온은이론적으로수술전가온을통해말초체온을미리증가시켜중심-말초체온차이를줄임으로써예방할수있으며, 여러연구를통해그효과가입증되었다 [12,13]. 일단재분포로인한저체온이발생되면중심체온을상승시키기는상대적으로어렵기때문에여러지침에서이를예방하기위한수술전가온을실시할것을권고하고있다 [12,14]. 그러나지침에서제시하고있는 30분이상의가온은수술전대기공간이없거나제한적인대부분의임상상황에서적용하기에어려움이있으며, 아직적절한시간에대한연구는많지않다 [12]. Brauer 등 [15] 은정규적으로 30분미만의수술전가온을시행하여효과적으로주술기저체온을감소시켰다고보고하였으며, Shin 등 [16] 은전신마취유도전, 사각근간상완신경총차단을시행하는평균 14분의짧은수술전가온으로효과적으로주술기저체온을감소시켰다고보고하였다. 또한, Horn 등 [17] 은 10분, 20분, 30분의수술전가온을한군과하지않은군을비교하여 10분의수술전가온으로도효과적이라고보고하였으나, 수술중저체온의발생률은 10분과 30분두군간의차이를보였다. 이에본저자들은권고에서주장한 30분의수술전가온과 10분의수술전가온이주술기저체온예방효과에미치는차이를비교하고자본논문을계획하였다. 대상및방법 본연구는시행전순천향대학교임상연구윤리위원회 (Institutional Review Board) 의승인을받았으며 (IRB no. 2017-05-003) 수술전일방문을통해연구에대해충분한설명후동의를받고 2017년 11월 1일부터 30일까지시행되었다. 18 세이상의미국마취과학회신체등급분류 1 3 에해당되고, 120 분이내의정규수술이예정된환자들을대상으로하였으며, 대상환자중수술전체온이 37.5 C 이상이거나 36 C 이하인경우, 부위마취를시행하거나부위마취와전신마취를병행하는경우, 체질량지수 (body mass index) 가 35 kg/m 2 이상인경우, 임산부인경우는제외되었다. 환자는수술전일선별후열쾌적지수의표현 (100-mm visual analog scale, VAS: 0 mm = 상상할수있는가장추운상태, 50 mm = 쾌적한상태, 100 mm = 상상할수있는가장더운상태 ) 에대해교육을받고 10분가온군 (group 10 minutes) 30명, 30분가온군 (group 30 minutes) 30명으로무작위배정되었다. 수술당일환자는병동에서정맥로를확보한후실온에서보관된수액을투여받기시작하였으며, 군에따라각각수술예정시작 30분또는 10분전에수술전대기공간 ( 회복실과동일한공간, 온도 : 26 ± 1 C) 에도착하였다. 도착직후환자의활력징후와고막체온을 (Thermoscan, infrared tympanic thermometer IRT 4020, Braun, USA) 측정하고 [18], 환자의이불밑에전신형전용포를깐후강제적공기가온기 (forced air warmer, Warm Touch TM 6000, Covidien, USA) 를사용하여 47 C로설정한후군에따라 10분가온군은 10분, 30분가온군은 30분의수술전가온을시행하였다. 가온을시작한후 10분간격으로고막체온을측정하고, 열쾌적지수를물어보았다. 환자의열쾌적지수가 60 이상으로열불쾌감을호소한경우에는가온온도를한단계씩 (45 C, 40 C, 34 C) 낮추었다. 본저자들이사용한강제적공기가온기는 47 C의가온온도에서 45분까지지속되며, 45분이지나면환자안전을위해 45 C 로감소되도록식품의약품안전처에서허가되었다. 가온이끝난후에는강제적공기가온기를제거한상태에서수술실로이동되었으며환자입실시의수술방의온도가기록되었다. 이후배정된군을알지못하는마취의에의해표준감시 ( 비침습적혈압, 심전도, 맥박산소포화도 ) 를실시하고, 환자의덮고있던이불을덮은상태에서 1% Propofol 2 mg/kg와 rocuronium 0.6 mg/kg 를사용하여마취유도를하였으며, 흡입마취제 (desflurane 또는 sevoflurane) 와 remifentanil을이용하여마취를유지하였다. 수술중심부체온을측정하기위하여기도확보직후비공에서 9 10 cm의깊이로비인두에체온계 (ETP1040, Ewha Biomedics, Korea) 를거치하여비인두체온을측정하였으며 15분간격으로기록하였다 [19]. 수술중에는면포를이용하여수동적보온을시행하였고, 환자가수술중 36.0 C 이하의저체온이발생한경우에는강제적공기가온기를 40 C로설정하여적극적가온을실시하였다. 수술이끝난후 pyridostigmine과 glycopyrrolate을사용하여근이완을반전시켰으며, 환자의의식이회복되고자발호흡이회복된후비인두체온계를제거하고회복실로이송하였다. 회복실에도착한직후군을모르는연구간호사에의해활력징후 448 www.anesth-pain-med.org
10 분수술전가온과저체온 와고막체온을측정한후 10분간격으로 30분까지고막체온과열쾌적지수, 3점척도 (0 = no shivering, 1 = intermittent, low intensity, 2 = moderate shivering, 3 = continuous, intense shivering) 를이용한수술후떨림을측정하였다. 회복실에서 36 C 이하의저체온이발생한경우, 강제적공기가온기를 40 C 로설정하여적극적가온을실시하였다. Horn 등 [17] 은 10분과 30분의수술전가온을시행하였을때수술중저체온의빈도가각각 31% 와 6% 라고보고하였다. 따라서, 본저자들은수술중저체온의빈도를이비율만큼줄일것으로가정하였고유의수준 0.05, 검정력 80%, 탈락률 10% 을고려하여, 각군의피험자수는 30명씩으로계산되었다. 본연구의통계적분석은 SPSS version 14 (SPSS Inc., USA) 를이용하여범주형변수는카이-제곱검정 (chi-square test) 또는피셔의정확도검정 (Fisher s exact test) 을시행하고연속형변수는 t-검정 (student t-test) 또는 Mann-Whitney 검사를통해통계분석을하였다. 수술전과중, 후의체온변화는 mixed effect model 을사용하여통계분석을하였으며, 그래프로그려졌다. 또한, 체온의시간에따른두군간차이는 Bonfferoni 방식을이용하여사후분석하였다. 모든연속형변수는평균 ± 표준편차로표기되었으며, 모든범주형변수는백분율과함께빈도를표기하였고, 통계적유의성은 P < 0.05로결정하였다. 결과 전체 66명의환자들을선별하여이중 6명은포함기준에부합하지않아제외되었고, 남은 60명을무작위로 10분가온군 30명, 30분가온군 30명으로배정하여연구를진행하였다. 연 구진행중 30분가온군중한명이수술전가온중저혈당쇼크를보여탈락되었으며, 10분가온군 30명, 30분가온군 29명이최종분석되었다 (Fig. 1). 두군간의나이, 성별, 몸무게, 키, 체질량지수, 미국마취과학회신체등급지수, 수술종류와마취시간, 수술전가온후마취유도까지의시간, 수술방의온도는두군간통계적차이를보이지않았다 (Table 1). 수술중저체온의빈도와회복실에서의저체온의빈도는통계적인차이를보이지않았으며, 수술후회복실에서의떨림의발생도통계적차이를보이지않았다 (Table 2). 열쾌적지수는수술전가온기간동안 30분가온군에서유의하게높은것으로나타났다. 30분가온군에해당하는환자중 5 명의환자는열쾌적지수 80 이상의심한열불쾌감을호소하여즉각적인온도조절이필요하였으며, 대부분의환자들은가온시간이 10분이경과한후에열불쾌감을호소하기시작하였다. 10분가온군에서는 1명의환자에서만 10분의가온이끝날시점에 80점의열불쾌감을호소하였고강제적공기가온기를제거한후해소되었다. 그러나수술후열쾌적지수는통계적차이를보이지않았다 (Table 3). 시간에따른체온의변화양상은수술전가온이끝난시점부터마취유도후 90분까지 30분가온군에서유의하게높은체온을나타냈다 (Fig. 2). 모든환자에서피부증상이나화상등의강제적공기가온으로인한부작용은보이지않았다. Enrollment Assessed for eligibility (n = 66) Excluded (n = 6) Not meeting inclusion criteria (n = 4) Declined to participate (n = 2) Other reasons (n = 0) Randomized (n = 60) Allocated to group 10 min (n =30) Received allocated intervention (n = 30) Did not receive allocated intervention (n = 0) Allocation Allocated to group 30 min (n =30) Received allocated intervention (n = 30) Did not receive allocated intervention (n = 0) Lost to follow-up (n = 0) Discontinued (n = 0) Analysed (n = 30) Excluded from analysis (n = 0) Follow-up Analysis Lost to follow-up (n = 0) Discontinued (hypoglycemia attack during pre-warming) (n =1) Analysed (n = 29) Excluded from analysis (n = 0) Fig. 1. CONSORT diagram of the Study. : the group of prewarming for 10 minutes, : the group of prewarming for 30 minutes. www.anesth-pain-med.org 449
Anesth Pain Med Vol. 13 No. 4 Table 1. Patient s Characteristics and Perioperative Data Table 3. Perioperative Thermal Comfort Scale Characteristics (n = 30) (n = 29) P value Thermal comfort scale (n = 30) (n = 29) P value Age (yr) 46.4 ± 17.8 50.8 ± 17.6 0.340 Sex (M/F) 15/15 13/16 0.796 Weight (kg) 66.8 ± 12.4 67.4 ± 13.0 0.840 Height (cm) 164.3 ± 10.6 165 ± 10.0 0.795 BMI (kg/m 2 ) 24.7 ± 3.2 24.7 ± 3.8 0.969 ASA PS classification 0.073 1 18 (60.0) 10 (34.5) 2 9 (30.0) 10 (34.5) 3 3 (10.0) 9 (31.0) Surgical type 0.888 Laparoscopic surgery 6 (20.0) 9 (31.0) Minor abdominal surgery* 1 (3.3) 1 (3.4) Spine surgery 1 (3.3) 1 (3.4) Orthopedic surgery 12 (40.0) 10 (34.5) Gynecologic surgery 6 (20.0) 3 (10.3) Others 4 (13.3) 5 (17.2) Anesthesia time (min) 97.1 ± 36.9 101.5 ± 39.5 0.664 Interval time (min) 19.9 ± 8.9 25.1 ± 14.0 0.099 Operating room temperature ( C) 21.95 ± 0.88 22.10 ± 0.68 0.487 Values are presented as mean ± SD, number only or number (%). : the group of prewarming for 10 minutes, : the group of prewarming for 30 minutes. BMI: body mass index, ASA PS: American Society of Anesthesiologists physical status. *Minor abdominal surgeries were herniorrhaphy. Table 2. Perioperative Hypothermia and Shivering Grade at PACU Variable 고 (n = 30) 찰 (n = 29) P value Intraoperative hypothermia 8 (26.7) 3 (10.3) 0.181 (< 36 C) Severity of hypothermia ( C) 0.216 Normothermia ( 36.0) 22 (73.3) 26 (89.7) Mild (35.5 35.9) 6 (20.0) 3 (10.3) Moderate (35.0 35.4) 2 (6.7) 0 (0.0) Hypothermia at PACU 5 (16.7) 4 (13.8) 1 (< 36.0) Shivering grade 1 Grade 0 28 (93.3) 29 (100.0) Grade 1 1 (3.3) 0 (0) Grade 2 1 (3.3) 0 (0) Grade 3 0 (0) 0 (0) Values are presented as number (%) (P value by Fisher s exact test). PACU: post anesthesia care unit, : the group of prewarming for 10 minutes, : the group of prewarming for 30 minutes. 본연구에서는전신마취를시행받는환자에서 47 C 의온도 를이용한수술전 10 분의짧은가온이효과적으로주술기저체 Preoperative worst thermal comfort scale 54.3 ± 8.6 61.0 ± 14.8 0.040 Postoperative thermal comfort scale 10 min 47.7 ± 6.3 51.7 ± 11.7 0.100 20 min 48.3 ± 5.3 48.8 ± 6.2 0.761 30 min 48.7 ± 5.1 48.3 ± 6.6 0.799 Values are presented as mean ± SD. : the group of prewarming for 10 minutes, : the group of prewarming for 30 minutes. Body temperature ( C) 38.0 37.5 37.0 36.5 36.0 35.5 At arrival preoperative area Fig. 2. Perioperative temperature. Error bars indicate ± 1SD of temperature at each time. Preoperative and postoperative core temperature of the patients was measured using tympanic membrane thermometer. Intraoperative core temperature of the patients was recorded every 15 minutes after anesthetic induction using nasopharyngeal probe. the temperature was higher in group 30 minutes from post-warming time to 90 minutes after anesthetic induction prewarming. *P < 0.05, P < 0.001. At arrival preoperative area: immediate after arrival of preoperative area, After warming: immediate after the end of warming, After anesthetic induction: immediate after anesthetic induction, At arrival PACU (post anesthesia care unit): immediate after arrival of PACU, PACU 10, 20, 30 min: 10, 20, 30 minutes after arrival of PACU. 온을감소시켰다. * * After warming After anesthetic induction 15 min 30 min 45 min 60 min 75 min 90 min 105 min 120 min At arrival PACU Time PACU 10 min PACU 20 min PACU 30 min 수술전가온시간에관한여러지침에서는 30 분이상의가온 을권고하고있다 [12,14]. 이는이전 Sessler 등 [20] 의연구에기초하고있는데, 이연구에서는재분포로이동되는열량이수술전 30분의가온이면얻을수있으며, 수술전가온시간이 1시간이상이되면발한과열불쾌감이증가하므로 30분에서 1시간이적절하다고보고하였다 [11]. 그러나이연구는가온전에 2시간동안 21 C의환경에노출하여열량이많이소실된후에시행된 * 450 www.anesth-pain-med.org
10 분수술전가온과저체온 연구이므로수술준비직후가온을시작하는일반적인임상상황과거리가있다. 이연구에의하면 2시간의 21 C 환경에노출후감소된열량은 15분이상의가온이실시된후에야회복하였다. 즉, 수술전 21 C 의환경에노출이없는임상상황에서는 Sessler 등 [20] 이주장한 30분보다더짧은기간의가온으로도충분한효과를나타낼수있을것으로추정해볼수있다. 또한 47 C 의높은온도를사용한수술전가온은말초체온을빠르게증가시켜말초-공기온도차이를감소시킴으로써그시간을좀더줄일수있을것으로추정된다 [20,21]. 또한, 최근에는 30분이내의수술전가온의효과에관한연구들이보고되고있다. Horn 등 [22] 은경막외마취하에제왕절개를시행받는환자에서 15분의수술전가온으로중심체온을효과적으로증가시켰다고보고하였으며 (37.1 ± 0.4 C vs. 36.0 ± 0.5 C), 경막외마취와전신마취를병행하여주요복부수술을시행받는환자에서경막외마취직후의 15분의가온만으로도주술기저체온을효과적으로줄일수있다고보고하였다 (72% vs. 6%) [23]. 또한 Shin 등 [16] 은관절경어깨수술을시행받는환자에서, 사각근간상완신경총차단을시행받는동안시행한평균 14분의짧은시간의전신마취유도전가온을통해효과적으로저체온을감소시켰다고보고하였다 (96.2% vs. 57.7%). Horn 등 [17] 은전신마취하에수술을받는환자의수술중저체온의빈도가수술전가온을 10분, 20분, 30분실시하였을때하지않은군에비해서효과적인감소를보였으며, 이는 10분의짧은수술전가온으로도효과적이라고보고하였다. 그러나이연구에서는회복실에서의저체온은수술전가온을한모든군에서차이를보이지않았지만, 수술중가온을필요로하는저체온의빈도는 10분의가온과 30분의가온간에통계적유의한차이를보였다 (31% [16/52] vs. 6% [3/50]). 그러나본연구에서는 Horn 등 [17] 의연구와달리 10분의가온과 30분의가온을시행받은두군간수술중 / 후저체온빈도모두에서통계적차이는나타나지않았으며, 수술후회복실에서의열쾌적지수, 떨림의빈도에도큰차이를보이지않았다. 그이유중첫번째로수술전가온을시행하는강제적공기가온의온도가다르기때문이라고추정해볼수있다. 본저자들이사용한가온온도는 Horn 등 [17] 이사용한 43 C 보다높은 47 C였으며, 이를통해더많은열량이전달되었을것으로추정된다. Sessler 등 [20] 은 40 C 와 43 C의온도를사용한가온을비교하였을때증가된말초열함유량의차이는크지않았지만, 가온직후부터나타난말초혈관확장정도와가온초기 40분에전달된열량이높았고, 증가된중심체온도두군간의차이를보였다고하였다. 즉, 더높은온도를사용한가온은더큰말초혈관확장을일으켜전달된열량이중심체온에반영됨으로써말초열량은비교적차이가없지만많은열량이전달된것으로추정해볼수있다. 그러므로, 47 C 의온도를사용한본연구에서전 www.anesth-pain-med.org 달된열량이 43 C의온도를사용한 Horn 등 [17] 의연구에비해서많았을것으로판단된다. 이로인해전반적인저체온빈도를줄임으로서 10분과 30분가온의저체온빈도차이를줄였을것으로추정해볼수있다. 두번째로, 수술전가온을시행한수술전대기장소의온도가이전연구에비해높았던것도연관이있을것으로추정된다. 본연구에서는연구를시행한기관의규정에따라회복실의온도를 26 ± 1 C 로유지하였으며, 수술전가온을시행한대기장소는회복실과같은장소였다. 이는 Horn 등 [17] 이수술전 / 중 / 후공간의온도를 23 C로유지한것과차이가있다. 즉, 본연구에서는수술전대기장소의온도를이전연구에비해높게유지하여, 수술전체온조절을위한혈관수축과가온전중심-말초체온차이가이전연구에비해서적었을것으로추정된다. Giesbrecht 등 [24] 은주변온도를 24.5 C 로유지하여 20.6 C 로유지한이전연구에비해기본적인열손실을 30 55 W 줄이고, 평균피부온도를 1.5 C 2.5 C 올렸다고보고하였다. 본연구에서도이결과와같은현상이나타났을것으로추정되나, 직접적인말초혈관온도및열량을측정하지않아서확인할수는없었다. 세번째로, 열불쾌감호소로인해수술전가온기간동안시행된온도조절이 30분가온군에서 10분가온군에비해더많이시행되었기때문에두군간전달된열량의차이를감소시켰을것으로추정해볼수있다. 빠르게상승하거나높은피부온도는발한과열불쾌감을야기할수있다. Sessler 등 [20] 의연구에의하면이런증상은 40/43 C 의강제적공기가온 1시간이후에나타날수있다고하였다. 본연구에서는짧은시간안에최대한의열을전달하기위해 47 C의높은온도를사용하였기때문에더빠르게발한과열불쾌감을야기할수있다. 이를확인하기위해환자들을수술전일에연구도중있을수있는열불쾌감을표현하도록교육하였으며, 수술전가온중조사에서 30분가온군에서 10분가온군에비해유의하게높은열쾌적지수를나타낸것으로나타났다. 또한, 80점이상의열불쾌감을호소한환자들의대부분은 10분이경과한시점에호소하기시작하였다. 이결과를통해 47 C의강제적공기가온기를이용하였을때는 10분의짧은시간이지난후발한과열불쾌감이발생할수있기때문에 10분의짧은가온이더적합할것으로생각된다. 그러나본연구에서시간에따른체온의변화는가온직후부터마취유도후 90분까지 30분가온과 10분가온두군에서차이를보였다. 이는가온기간중온도조절에도불구하고 30분가온군에서 10분가온군에비해많은열량이전달되었기때문인것으로추정된다. 그러나, 마취유도후 90분이후에는통계적인차이를보이지않아재분포와수술전가온이많은영향을미치는시기가지나다른요인들에영향을더많이받으면서천천히그차이가줄었을것으로추정해볼수있다. 451
Anesth Pain Med Vol. 13 No. 4 또한, 이연구에서는가온으로인한중심체온의변화양상이이전연구와다르게나타났다. Sessler 등 [20] 은수술전가온중중심온도는강제적공기가온으로인한혈관확장으로인해가온을시작한첫 30 45분에는오히려감소 ( 약 0.2 C) 하였다가이후에서서히증가된다고하였다. 그러나본연구에서 10분가온군과 30분가온군모두에서가온직후중심체온은감소되지않고오히려상승하였다. 이는가온전 21 C 의 2시간노출이있는 Sessler 등 [20] 의연구와다르게임상적으로수술준비직후가온이시작되었고, 수술전가온이시행된공간의온도가 26 ± 1 C 로유지되었기때문에가온전체온유지를위한혈관수축이 Sessler 등 [20] 의연구에비해적고, 보유한열량이더많았기때문으로추정된다. 그러나본연구는몇가지의제한점을갖는다. 첫번째, 본연구의군수는 Horn 등 [17] 의연구결과를바탕으로계산되었으며, 이는 43 C의강제적공기가온기의온도를이용한연구이므로 47 C의강제적공기가온기의온도를사용한본연구와달라, 군수가상대적으로적어검정력이감소되었을가능성이있다. 두번째, 이연구는 120분이내의짧은수술을대상으로하여수술중저체온발생률이높은대부분의주요수술이제외되었기때문에 120분이상의주요수술을시행받는환자의경우까지확장시켜생각할수없다. 추후에 120분이상의주요수술을대상으로하는추가의연구가필요할것으로보인다. 세번째, 이연구에서는말초체온및열량을직접적으로측정하지않아전달된열량을추정할수밖에없었다. 그러나주술기저체온을결정하고이에따른결과에영향을주는임상적으로중요한수치는중심체온이라고생각이되며이를측정하는것만으로도충분하다고생각된다. 결론적으로, 120분미만의수술을받는환자들에게서 47 C 의강제적공기가온기를이용한수술전 10분의가온은수술전 30분의가온과비교해낮은심부체온을보이지만주술기저체온의빈도는비슷하게감소시킨다. 즉, 47 C 의온도를이용한 10 분의가온은 30분이상의가온이쉽지않은임상상황에서적용할수있는좋은방법이다. REFERENCES 1. Young VL, Watson ME. Prevention of perioperative hypothermia in plastic surgery. Aesthet Surg J 2006; 26: 551-71. 2. Torossian A, Bräuer A, Höcker J, Bein B, Wulf H, Horn EP. Preventing inadvertent perioperative hypothermia. Dtsch Arztebl Int 2015; 112: 166-72. 3. Just B, Delva E, Camus Y, Lienhart A. Oxygen uptake during recovery following naloxone. Relationship with intraoperative heat loss. Anesthesiology 1992; 76: 60-4. 4. Frank SM, Fleisher LA, Olson KF, Gorman RB, Higgins MS, Breslow MJ, et al. Multivariate determinants of early postoperative oxygen consumption in elderly patients. Effects of shivering, body temperature, and gender. Anesthesiology 1995; 83: 241-9. 5. Frank SM, Fleisher LA, Breslow MJ, Higgins MS, Olson KF, Kelly S, et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. JAMA 1997; 277: 1127-34. 6. Heier T, Caldwell JE, Sessler DI, Miller RD. Mild intraoperative hypothermia increases duration of action and spontaneous recovery of vecuronium blockade during nitrous oxide-isoflurane anesthesia in humans. Anesthesiology 1991; 74: 815-9. 7. Lenhardt R, Marker E, Goll V, Tschernich H, Kurz A, Sessler DI, et al. Mild intraoperative hypothermia prolongs postanesthetic recovery. Anesthesiology 1997; 87: 1318-23. 8. Rajagopalan S, Mascha E, Na J, Sessler DI. The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology 2008; 108: 71-7. 9. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of wound infection and temperature group. N Engl J Med 1996; 334: 1209-15. 10. Torossian A; TEMMP (Thermoregulation in Europe Monitoring and Managing Patient Temperature) Study Group. Survey on intraoperative temperature management in Europe. Eur J Anaesthesiol 2007; 24: 668-75. 11. Matsukawa T, Sessler DI, Sessler AM, Schroeder M, Ozaki M, Kurz A, et al. Heat flow and distribution during induction of general anesthesia. Anesthesiology 1995; 82: 662-73. 12. Forbes SS, Eskicioglu C, Nathens AB, Fenech DS, Laflamme C, McLean RF, et al. Evidence-based guidelines for prevention of perioperative hypothermia. J Am Coll Surg 2009; 209: 492-503. 13. Connelly L, Cramer E, DeMott Q, Piperno J, Coyne B, Winfield C, et al. The optimal time and method for surgical prewarming: a comprehensive review of the literature. J Perianesth Nurs 2017; 32: 199-209. 14. Horn EP, Klar E, Höcker J, Bräuer A, Bein B, Wulf H, et al. Prevention of perioperative hypothermia : implementation of the S3 guideline. Chirurg 2017; 88: 422-8. 15. Bräuer A, Waeschle RM, Heise D, Perl T, Hinz J, Quintel M, et al. Preoperative prewarming as a routine measure. First experiences. Anaesthesist 2010; 59: 842-50. 16. Shin KS, Lee GY, Chun EH, Kim YJ, Kim WJ. Effect of short-term prewarming on body temperature in arthroscopic shoulder surgery. Anesth Pain Med 2017; 12: 388-93. 17. Horn EP, Bein B, Böhm R, Steinfath M, Sahili N, Höcker J. The effect of short time periods of pre-operative warming in the pre- 452 www.anesth-pain-med.org
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