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Ch24. Anesthesia for thoracic surgery

Ch24. Anesthesia for thoracic surgery. 전공의 1 년 노지성. PHYSIOLOSIC CONSIDERATION DURING THORACIC ANESTHESIA. 마취에 있어서 특별한 physiologic set 을 요구한다 . lat. decubitus position, open pneumo thorax, one-lung ventilation 등 THE LATERAL DECUBITUS POSITION

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Ch24. Anesthesia for thoracic surgery

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  1. Ch24. Anesthesia for thoracic surgery 전공의 1년 노지성

  2. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • 마취에 있어서 특별한 physiologic set을 요구한다. • lat. decubitus position, open pneumo thorax, one-lung ventilation등 • THE LATERAL DECUBITUS POSITION • lung, pleura, esophagus, greater vessel, other mediastinal structure, vertebra등의 op에 적합한 field를 제공한다. • 그러나 이 자세는 정상적인 V/Q(ventilation/perfusion) relationship에 변화를 가져온다. 이는 마취의 induction, mechanical ventilation, surgical retraction등에 의해 더욱 심화된다. • 즉, perfusion은 dependent part(lower)에 잘 되는 반면, ventilation은 upper lung에서 더 잘 이루어져 V/Q mismatch가 심화되어 hypoxemia의 risk가 커진다. • The Awake State • V/Q matching preserved → lower lung > upper lung • Lower lung은 더 많은 pressure와 ventilation을 받는다. • p: gravity 때문에 ↑  ,   v: abd. weight supporting disproportionate에 의한 hemidiaphragm의 contraction efficiency의 증가와 compliance curve에서 dependent lung이 favor part를 차지하므로 ↑

  3. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • Induction of Anesthesia • functional residual capacity (FRC) ↓ • p-v curve에서 upper lung의 compliance가 more favor • 결과적으로 upper lung이 ventilation이 더 잘되! →V/Q mismatching이 초래된다. • Positive Pressure Ventilation • compliance의 증가로 upper lung이 CPPV이 더 잘된다. →muscle paralysis는 abd. contents를 rise up시켜 lower hemithorax를   더욱 restrict시킨다. • upper lung을 open시키면 compliance는 더 증가되어 V/Q mismatching이   심화되어 hypoxemia를 더욱 조장한다.

  4. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • THE OPEN PNEUMOTHORAX • normal lung : negative pleural pressure로 인해 expand  →lung open시 pressure lost, elastic recoil 때문에 collapse • opened lateral lung을 가진채 spontaneous ventilation  →paradoxical respiration & mediastinal shift초래 → hypoxemia와 hypercarpnia → positive pressure ventilation으로 overcome • Mediastinal Shift • Lateral position에서 spontaneous ventilation시에 inspiration시 아랫쪽 lung에서는 pleural pressure가 negative   pressure가 되어 mediastinum이 downward shift(insp.) & upward  shift(expi.) f-24-3 • *paradoxical respiration • open pneumothorax시 to-and-fro gas flow between dependent &nondependent lung • inspiration시 pneumothorax ↑ →upper lung에서 carina를 통과하여 gas   flow가 dependent lung으로, expiration시는 reverse(upper lung으로)

  5. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • ONE-LUNG VENTILATION • collapse된 lung은 perfusion은 계속되면서 ventilation은 안되기 때문에  right-to-left intrapulmonary shunt가 발생한다.(20~30%) • unoxygenated blood (from upper lung)와 oxygenated blood(dependent lung)가 섞여 PA-a (alveolar-to-arterial) O2 gradient를 widen →hypoxemia • 다행히도 hypoxic pulmonary vasoconstriction(HPV)과 surgical compression이 upper lung으로의 blood flow를 감소시킨다. • *HPV를 방해하여 Rt.-to-Lt. shunt를 악화시키는 인자들.  ①very high or very low pul. a. pressure  ②hypocapnea  ③high or very low mixed venous PO2  ④vasodilator such as nitroglycerin, nitroprusside, β-adrenergic agonist, Ca channel blocker  ⑤pul. infection  ⑥inhalation anesthetics • *ventilated lung으로의 blood flow를 감소시켜 결과적으로 collapsed lung  으로의 blood flow를 증가시켜 HPV를 저해하는 인자들  ①high PEEP에 의한 high mean airway pressure in ventilated lung, hyperventilation, or high peek inspiratory pressure  ②low FiO2  ③vasoconstrictor  ④intrinsic PEEP • 참고로 arterial CO2 tension은 two-lung ventilation과 별반 차이를 보이지 않는다.

  6. TECHNIQUES FOR ONE-LUNG VENTILATION <3 techniques> 1.placement of a double-lumen endobronchial tube → most often use 2.use of a single-lumen endobronchial tube in conjunction with a bronchial blocker 3.use of a single-lumen endobronchial tube

  7. TECHNIQUES FOR ONE-LUNG VENTILATION • DOUBLE-LUMEN ENDOBRONCHIAL TUBES • <double-lumen tube의 장점>  1.ease of placement  2.ability of ventilating of either or both lung  3.ability of suction  either lung • <double-lumen tube의 일반적 특징>  1.longer bronchial lumen은 either lunger의 main bronchus까지 들어가고,    shorter tracheal lumen은 lower trachea 까지만 들어간다.  2.preformed curve가 있어 원하는 쪽으로 삽관가능 3.bronchial & tracheal cuff • 두개의 cuff를 모두 inflation시켜 한쪽 lung은 collapse시키고, 다른 쪽 lung으로만 ventilation이 되게 하는 원리. • 양쪽 bronchus의 anatomical difference 때문에 Rt & Lt가 각각 따로  design되어 있다. • 가장 많이 사용하는 Robert-Shaw type의 경우 size가 35, 37, 39, 41F    (각각 내경이 5.0, 5.5, 6.0, 6.5mm)가 있는데, 일반적으로 남자는 39F,  여자는 37F를 사용한다.

  8. TECHNIQUES FOR ONE-LUNG VENTILATION • Anatomic Considerations • trachea : 11~13cm(cricoid cartilage(C6) ~ sternomanubrial joint(T5)) • main bronchus  1. Rt.는 25도, Lt.는 45도로 꺾여 분지된다.  2. Rt. bronchus는 upper, middle, lower의 three lobe branch.    Lt. bronchus는 upper & lower lobe branch.  3.Rt. & Lt. upper lobe의 orifice는 carina에서 각각 1~2.5cm, 5cm정도에 위치. • Rt.-sided endobronchial tube에는 Rt. upper lobe orifice의 anatomical   variation때문에 특별히 Rt. upper lobe을 ventilation시켜주기 위한 “slit”   이 있다. 그러나 대부분의 마취과 의사들은 op side에 관계없이 Lt. sided   tube를 사용한다.(Lt.-sided tube는 Rt. thoracotomy용 이지만, Lt.-sided   surgery시에는 Lt. bronchus를 clamping하기에 앞서 tube를 trachea쪽으로 withdrawal시킨다. • 어떤 tube들은 carinal hook를 가지고 있는데,(eg, Carlens and White)  tube placing의 어려움 때문에 많이 사용하지 않는다.

  9. TECHNIQUES FOR ONE-LUNG VENTILATION • Placement of Double-Lumen Tubes • distal curvature가 앞쪽으로 concave하게 진행. • tip이 larynx를 통과하면 intubation할 bronchus쪽으로 90〫rotation을 시킨 후, 저항이 느껴질 때 까지 진행시킨다.(보통 이때의 길이는 teeth에서 29cm 정도가 된다. • confirm은 flexible FOB를 사용하여 눈으로 직접 확인한다. • 문제가 생기면 “tube exchanger”를 사용하여 smaller regular tube로 즉시 tube change를 한다. • 3.6~4.2mm 정도의 외경을 가진 bronchoscope으로 tracheal lumen을 통하여 carina까지 advance하여 bronchial cuff의 위치를 확인하는데, bronchial cuff는 푸른색을 띠며, 보이지 않을 경우에는 cuff가 more advance하여 left lower lobe을 obstruction시킬 수 있다. • optimal하게 place되었다면 bronchial cuff를 inflation시킨 후 breathing sound를 들어보면, endobronchial ventilation을 시켰을 때 새는 소리가 나지 않는다. • position change 후에도 breathing sound 확인하는 것을 잊지 말자! • malpositioning(Lt.-sided tube에서)   →tube가 너무 깊게 혹은 얕게 들어갔을 때, 아니면 Rt. bronchus로 들어 갔을 때.   →너무 깊어서 Lt. upper or lower lobe의 orifice를 cuff가 막게 되어  lumen의 opening이 Lt. upper or lower lobe bronchus에 위치하게  되면, 한쪽 lobe만이 ventilation되게 되어, hypoxia를 초래한다.   →충분히 advance가 안되면 bronchial cuff가 Rt. bronchus를 막을 수가   있다. • Rt.-sided tube에 문제가 생기는 경우는 Rt. upper lobe의 orifice가  carina에 너무 가깝게 있는 경우다.(<1cm) 이런 경우에는 bronchial cuff가   Rt. upper lobe을 막을 수 있는데, 이럴 경우에는 Lt.-sided tube를 사용하 는 것이 좋다. • 원치 않게 wrong bronchus로 intubation 되었다면, flexible FOB를 bronchial lumen으로 집어넣어 scope guide하에 repositioning 할 수 있다. • Complications of Double Tubes  ①hypoxemia due to tube malplacement or occlusion  ②traumatic laryngitis(특히 carinal hook가 있는 tube에서)  ③tracheobronchial rupture from overinflation of bronchial cuff  ④inadvertent suturing of the tube to bronchus during surgery

  10. TECHNIQUES FOR ONE-LUNG VENTILATION • SINGLE-LUMEN ENDOTRACHEAL TUBES WITH A BRONCHIAL BLOCKER • bronchial blockers are inflatable device passed alongside or through a single-lumen ETT • retractable bronchial blocker를 위한 side channel이 있는 single lumen ETT가 상업적으로 많이 사용된다(eg, Univent tube) • 장점은 double lumen과 달리 one lung op.후에 regular ETT로 바꿀 필요가 없다는 것이고, 단점은 blocked lung의 collapse가 side channel이 작은 관계로 서서히(때로는 불완전하게) 이루어진다는 것이다. • inflatable catheter(Forgarty)가 bronchial blocker로써 regular ETT와 짝을 이루어 사용할 수 있다.  →isolated lung의 suction이나 ventilation이 불가능. • bronchial blocker는 pediatric patients의 one-lung ventilation이나 성인에서의 tamponating endobronchial bleeding의 anesthesia에 유용하다. • SINGLE-LUMEN ENDOBRONCHIAL TUBES • rarely used

  11. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS • 1.Tumors • -benign : hamartomas, bronchial adenoma •  malignant : small cell("oat cell")ca., non small cell ca. (epidermoid,     adenocarcinomas, large cell ca.) •  Clinical Menifestation •  -Sx : cough, hemoptysis, dyspnea, wheezing, wt. loss, fever or         productive sputum, chest pain(pleural extension), •   hoarsness(mediastinal involve),Horner syn.(sympathetic chain           involve)   dysphagia(esophagus compression),pancoast synd.(sup.       sulcus involve) •   meta : brain, bone, liver, and adrenal gland •  -paraneoplastic syndrome : ectopic hormone production &              immunologic cross-reactivity between the tumor and normal tissue •   (Cushing synd., hyponatremia, hypercalcemia,Lambert-Eaton synd.등)

  12. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS • Treatment •  -surgery : choice of curative tx.(LN involve와 distant meta가 없다면) •  -resectability & operability : resectability determined by anatomic      stage of tumor, operability depend on extent of procedure &          physiologic status •  Operative Criteria for Pneumonectomy •  -measure PFT : directly related to op risk •  -m/c used criteria for operability •  →postoperative FEV1 greater than 800ml •    postoperative FEV1 = •  %blood flow to remaining lung × total FEV1

  13. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS • 2.Infection • -may present at solitary nodule or •  cavitary lesion(necrotizing pneumonitis)  •  → empyema, massive hemoptysis • -bacteria(anaerobies, mycoplasma, norcadia) •  fungi(histoplasma, coccidioides,..) • 3.Bronchiectasis • -dilatation of bronchi : severe or reccurent infl. & obstruction of       bronchi • -resection Ix. : massive hemoptysis, failed conservative measure,       disease localized

  14. ANESTHESIA FOR LUNG RESECTIONANESTHETICCONSIDERATIONS • 1.Preoperative Management • -smokong is risk factor for COPD & coronary artery disease. • -echocardiography : baseline cardiac function assess •  dobutamine stress echo:detect occult coronary a. disease • -tracheal, bronchial deviation : airway compression • -high risk pt. complication reduce •  Premedication • -anticholinergics : ↓ copious secretion

  15. ANESTHESIA FOR LUNG RESECTIONANESTHETICCONSIDERATIONS • 2.Intraoperative Management • Preparation • -various size single & double lumen tubes, flexible FOB, tube          exchanger, CPAP delivery system, anesthesia circuit adaptor prepare • Venous Access • -at least one large-bore IV line(14~16G) • Monitoring • -direct a. pressure monitoring : one lung anesthesia, large tumor       resection • -CVP : net effect of venous capacitance, blood volume, rt. ventricular   function • -pul. a. catheterization : pul HTN, cor pulmonale, lt. ventricular        dysfunction • Induction of Anesthesia • -adequate preoxygenation, IV barbiturate is used for most pt. • -peep prevent atelectasis, paradoxical mediastinal shift • Positioning • -most lung resections are performed via post. thoracotomy with the    pt. in the lat. decubitus position

  16. ANESTHESIA FOR LUNG RESECTIONmaintenace of anesthesia • -halogenated agent(halo, isoflu, sevoflu, or desflu) with opioid is        prefer • -halogenated agent의 장점 • ①potent dose related bronchodilation • ②depression of airway reflexes • ③ability to use a high O2 concentration • ④capacity for relatively rapid adjustment in anesthetic depth • ⑤minimal effects on HPV • -opioid의 장점 • ①minimal hemodynamic effects • ②depression of airway reflexes • ③residual postop. analgesia • -N2O not used : decrease FiO2 • -IV fluid restricted in pul. restriction pt. • Management of One-Lung Ventilation • -greatest risk : hypoxemia → 100% O2 use • -if peak pressure rise(>30cm H2O) •  : tidal volume reduce 6~10ml/kg •   & increase rate • Alternatives to One-lung Ventilation • -adequate oxygenation be maintained • -high frequency positive pressure ventilation & high frequency jet      ventilation used

  17. ANESTHESIA FOR LUNG RESECTIONpostoperative management • General Care • -most pt. are extubated early : decrease risk of pul. barotrauma, pul. infection(double lumen은 regular tube로 change) • -posop hypoxemia & resp. acidosis commom → cause mainly by atelectasis • -postop hrr : chest tube drainage increase, hypotension, tachycardia • falling Hct. • -semiupright posion, supplement oxygen close monitoring • Postoperative Analgesia • -IV opioids small dose superior to IM large dose • -0.5% ropivacaine inject above & below two levels of thoracotomy incision • -cryoanalgesia, epidural ( morphine 5~7mg/10~15ml saline) • Postoperative Complications • -atelectasis : blood clots & thick secretion • airleak from operative hemithorax : bronchopleural fistula inadequate blood flow or inf. torsion of lobe or segment • herniation of heart into the hemithorax • phrenic, vagus, lt. recurrent laryngeal n. injury

  18. SPECIAL CONSIDERATIONS FOR PATIENTS UNDERGOING LUNG RESECTION • Massive Pulmonary Hemorrhage • -definition : 500~600ml< from tracheobronchial tree within 24 hrs.(모든 hemoptysis case의 1~2%정도) • -result of TB, bronchiectasis, neoplasm, transbronchial biopsies • -embolization, tamponade, laser coagulation • -bleeding side lung을 dependent 쪽으로 lateral position유지 •   →bleeding tamponade • -sedation은 불필요. → 이미 충분히 hypoxic이니까. (만일 intubated state   면 coughing을 막기위해 sedation이 helpful.) • -intubation시에는 bleeding swallowing에 의한 full stomach임을 •  감안하여, awake 상태로 rapid sequence induction 시행. • -semiupright position maintained & cricoid pressure • -airway의 large blood clot을 suction하는데, sodium bicarbonate가 유용   하다.

  19. SPECIAL CONSIDERATIONS FOR PATIENTS UNDERGOING LUNG RESECTION • Pulmonary Cysts & Bullae • -congenital or result from emphysema • -rupture of air cavity → tension pneumothorax • -N2O cIx.(it can expand air space & rupture) • Lung Abscess • -result from primary pul. infection, obstructing pul. neoplasm, 드물게    전신 감염의 혈행성 전이. • -isolating two lungs early to prevent soiling of healthy one with pus • -affected lung in dependent position • Bronchopulmonary Fistula • -result following lung resection, rupture of pul. abscess, pul.           barotrauma, spontaneous rupture of bullae • -대부분은 conservative treat로 치료됨. • conservative Tx. 실패시 op. → recommend awake intubation with double lumen tube wide rapid sequence induction

  20. ANESTHESIA FORtracheal resection • Preoperative Considerations • -performed for tracheal stenosis, tumor • -flow-vol. loops confirms the location of obs. & evaluating severity • Anesthetic Considerations • -anticholinergics만 premedi. • -lower tracheal resection시는 left radial a.에 canulation하는 것이 좋다   (innominate artery가 compression될 수 있으므로) • -halothane으로 slow induction.(respiratory depression이 적고, airway    자극이 덜하므로.) • -induction시에 spontaneous ventilation을 유지하며, muscle relaxant는    사용 안 한다.(muscle paralysis후에 complete airway obs.가 올수 있다.)

  21. ANESTHESIA FOR THORACOSCOPIC SURGERY • -diagnostic & treatmental procedure • -lung biopsy, segmental & lobar resection, pleurodesis, esophageal     procedure, pericardectomy • -3개 또는 그 이상의 small incision을 통해 시술하며, position은 lat.        decubitus position. anesthesia는 다른 open procedure에 준해서 •  시행한다.

  22. ANESTHESIA FOR DIAGNOSTIC THORACIC PROCEDURES • Bronchoscopy • -flexible FOB (discussed already) • -rigid bronchoscopy : foreign body removal, tracheal dilatation under   general anesthesia • -술기를 시행하는 operator와 airway를 공유해야하는 어려움이 있다. •  (그러나 보통 5~10분정도의 short procedure.) • -iv induction시에 potent inhalation anesthesia with 100% O2 with short   or intermediate muscle relaxant.(propofol과 같은 total iv anesthetics도   유용) • -3 techniques •  ①apneic oxygenation with a small catheter alongside •    the bronchoscope •  ②conventional ventilation through the side arm of •    ventilatory bronchoscope •  ③high frequency ventilation through injector type bronchoscope • Mediastinoscopy • -access to mediastinal LN & •  establish Dx. or resectability intrathoracic malignancies • -Cx. : ①vagally reflex bradycardia ②excercise hrr. ③cb ischemia •       ④pneumothorax ⑤air embolism ⑥recurrent laryngeal n. damage • Bronchoalveolar lavage(BAL) • -pt. with pulmonary alveolar proteinosis • -indicated for severe hypoxemia or worsening dyspnea

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