Ch 24. ANESTHESIA FOR THORACIC SURGERY

1. Ch 24. ANESTHESIA FOR THORACIC SURGERY R1. 이송이

2. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA 마취에 있어서 특별한 physiologic set을 요구 • lat. decubitus position, open pneumothorax, one-lung ventilation 등 • LATERAL DECUBITUS POSITION • lung, pleura, esophagus, greater vessel, other mediastinal structure, vertebra등의 op에 적합한 field를 제공한다. • 이 자세는 정상적인 V/Q (ventilation/perfusion) relationship에 변화를 가져온다. 마취의 induction, mechanical ventilation, surgical retraction등에 의해 더욱 심화 • perfusion은 dependent part (lower)에 잘 되는 반면, ventilation은 upper lung에서 더 잘 이루어져 mismatch가 심화되어 hypoxemia의 risk가 커진다.

3. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • Awake State • V/Q matching preserved → lower lung > upper lung • Lower lung은 더 많은 perfusion과 ventilation을 받는다. p: gravity 때문에 ↑  ,   v: abd. weight supporting disproportionate에 의한 hemidiaphragm의 contraction efficiency의 증가와 compliance curve에서 dependent lung이 favor part를 차지하므로 ↑

4. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • Induction of Anesthesia • Functional residual capacity (FRC) ↓ • P-V curve에서 upper lung의 compliance가 more favor • 결과적으로 upper lung이 ventilation이 더 잘된다. →V/Q mismatching이 초래

5. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • Positive Pressure Ventilation • compliance의 증가로 upper lung이 CPPV이 더 잘된다. →근이완제에 의한 muscle paralysis는 abd. contents를 rise up시켜 lower hemithorax를 더욱 restrict • upper lung을 open시키면 compliance는 더 증가되어 V/Q mismatching이  심화되어 hypoxemia를 더욱 조장

6. 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 가진 체 spontaneous ventilation  →paradoxical respiration & mediastinal shift초래 → hypoxemia와 hypercarpnia → positive pressure ventilation으로 overcome

7. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • Mediastinal Shift • Lateral position에서 spontaneous ventilation시에 inspiration시 아랫쪽 lung에서는 pleural pressure가 negative   pressure가 되어 mediastinum이 downward shift (insp.) & upward  shift (expi.) *paradoxical respiration : • open pneumothorax시 dependent &nondependent lung 사이에 to-and-fro gas flow 형성된다. • inspiration시 pneumothorax ↑ →upper lung에서 carina를 통과하여 gas   flow가 dependent lung으로, expiration시는 reverse (upper lung으로)

8. 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 • Hypoxic pulmonary vasoconstriction (HPV)과 surgical compression이 upper lung으로의 blood flow를 감소시켜 V/Q mismathing 을 줄임.

9. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • HPV를 방해하여 Rt.-to-Lt. shunt를 악화시키는 인자들 - very high or very low pulmonary a. pressure - hypocapnea - high or very low mixed venous PO2 - Vasodilator (nitroglycerin, nitroprusside, β-adrenergic agonist, CCB) - pul. infection - inhalation anesthetics

10. PHYSIOLOSIC CONSIDERATIONDURING THORACIC ANESTHESIA • ventilated lung으로의 blood flow를 감소시켜 결과적으로 collapsed lung 으로 blood flow를 증가시키는 요인 - high PEEP에 의한 high mean airway pressure in ventilated lung, hyperventilation, or high peek inspiratory pressure - low FiO2 - vasoconstrictor - intrinsic PEEP • arterial CO2 tension은 two-lung ventilation과 별반 차이를 보이지 않는다.

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

12. 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

13. TECHNIQUES FOR ONE-LUNG VENTILATION <double-lumen tube의 일반적 특징>  1.longer bronchial lumen은 either lung의 main bronchus까지 들어가고, shorter tracheal lumen은 lower trachea 까지만 들어간다.  2.preformed curve가 있어 원하는 쪽으로 삽관 가능 3.bronchial & tracheal cuff

14. TECHNIQUES FOR ONE-LUNG VENTILATION • 두개의 cuff를 모두 inflation시켜 한쪽 lung은 collapse시키고, 다른 쪽 lung으로만 ventilation • 양쪽 bronchus의 anatomical difference 때문에 Rt & Lt가 각각 따로  design • 가장 많이 사용하는 Robert-Shaw type의 경우 size가 35, 37, 39, 41F (각각 내경이 5.0, 5.5, 6.0, 6.5mm)가 있으며, 남자는 39F,  여자는 37F를 사용

15. 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.

16. TECHNIQUES FOR ONE-LUNG VENTILATION • Anatomic Considerations • Rt.-sided endobronchial tube에는 Rt. upper lobe orifice의 anatomical   variation 때문에 Rt. upper lobe을 ventilation 시켜주기 위한 “slit” 이 있다. • 어떤 tube들은 carinal hook를 가지고 있는데, (eg, Carlens and White)  tube placing의 어려움 때문에 많이 사용하지 않는다.

17. TECHNIQUES FOR ONE-LUNG VENTILATION • Placement of Double-Lumen Tubes • distal curvature가 앞쪽으로 concave하게 진행 • tip이 larynx를 통과하면 intubation할 bronchus쪽으로 90〫° rotation을 시킨 후, 저항이 느껴질 때 까지 진행 (보통 이때의 길이는 teeth에서 29cm 정도가 된다.)

18. TECHNIQUES FOR ONE-LUNG VENTILATION • Placement of Double-Lumen Tubes • confirm은 flexible FOB를 사용하여 눈으로 직접 확인한다. • 문제가 생기면 smaller regular tube로 먼저 intubation 후 “tube exchanger”를 사용하여 double lumen endobronchial tube로 교환 • 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 ventilation을 시켰을 때 새는 소리가 나지 않는다. • position change 후에도 breathing sound 확인해야 된다.

19. TECHNIQUES FOR ONE-LUNG VENTILATION • Placement of Double-Lumen Tubes • Malpositioning (Lt.-sided tube에서) → Rt. bronchus로 들어 갔을 경우   → 너무 깊어서 Lt. upper or lower lobe의 orifice를 cuff가 막게 되면 한쪽 lobe만이 ventilation  hypoxia 초래   → 충분히 advance가 안되면  bronchial cuff가 Rt. bronchus를 막을 수가 있다 • Rt.-sided tube에 문제가 생기는 흔한 원인은 Rt. upper lobe의 orifice가  carina에 너무 가깝게 있는 것이다. (<1cm) 이런 경우에는 bronchial cuff가 Rt. upper lobe을 막을 수 있는데, 이럴 경우에는 Lt.-sided tube를 사용 • 원치 않게 wrong bronchus로 intubation 되었다면, flexible FOB를 bronchial lumen으로 집어넣어 scope guide하에 repositioning 할 수 있다.

20. TECHNIQUES FOR ONE-LUNG VENTILATION < Complications of Double Tubes > • Hypoxemia due to tube malplacement or occlusion • Traumatic laryngitis (특히 carinal hook가 있는 tube에서) • Tracheobronchial rupture from overinflation of bronchial cuff • Inadvertent suturing of the tube to bronchus during surgery

21. 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 • 장점: double lumen과 달리 one lung op.후에 regular ETT로 바꿀 필요가 없다 단점:blocked lung의 collapse가 side channel이 작은 관계로 서서히 이루어짐 • Inflatable catheter (Forgarty)가 bronchial blocker로써 사용 가능 →isolated lung의 suction이나 ventilation이 불가능 • bronchial blocker는 pediatric patients의 one-lung ventilation이나 성인에서의 tamponating endobronchial bleeding의 anesthesia에 유용 • SINGLE-LUMEN ENDOBRONCHIAL TUBES • rarely used

22. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS 1.Tumors -Benign : hamartomas, bronchial adenoma -Malignant : small cell ("oat cell") cancer non small cell cancer (epidermoid, adenocarcinomas, large cell ca.)

23. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS < Clinical Manifestation > • 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 & 종양과 정상조직 사이 간의 immunologic cross-reactivity에 의한 증후군 (Cushing synd., hyponatremia, hypercalcemia, Lambert-Eaton synd.등)

24. 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

25. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS < 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

26. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS 2. Infection • Solitary nodule이나 cavitary lesion (necrotizing pneumonitis)   → empyema, massive hemoptysis • 원인: 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 Localized disease

27. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS 1. Preoperative Management • Smoking 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 • Premedication - Anticholinergics : ↓ copious secretion - Moderate or severe respiratory dis. 환자의 경우 sedative premedication을 하지 않는다.

28. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS 2. Intraoperative Management • Preparation - Various size single & double lumen tubes - Flexible FOB - Tube exchanger - CPAP delivery system - Anesthesia circuit adaptor • Venous Access - 한 개 이상의 Large-bore IV line (14~16G)

29. ANESTHESIA FOR LUNG RESECTIONPREOPERATIVE CONSIDERATIONS • 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 anesthetic - CPPV prevents atelectasis, paradoxical respiration, mediastinal shift • Positioning - 대부분의 lung resection은 lat decubitus position에서 posterior thoracotomy를 통해

30. ANESTHESIA FOR LUNG RESECTIONmaintenace of anesthesia 1. Opioid와 halogenated agent (halo, isoflu, sevoflu, or desflu)를 함께 사용하는 것이 선호된다. < Halogenated agent의 장점 > ① Potent dose related bronchodilation ② Depression of airway reflexes ③ Ability to use a high O2 concentration ④ Capacity for relatively rapid adjustment in anesthetic depth ⑤ Minimal effects on HPV < Opioid의 장점 > ① Minimal hemodynamic effects ② Depression of airway reflexes ③ Residual postop. Analgesia 2. N2O not used : decrease FiO2 3. IV fluid restricted in pulmonary resection patient

31. ANESTHESIA FOR LUNG RESECTIONmaintenace of anesthesia 4. Management of One-Lung Ventilation -Greatest risk : hypoxemia → 100% O2 use -If peak pressure rise (>30cm H2O)   : tidal volume reduce 6~8ml/kg & increase rate -Hypoxemia Tx • Periodic Inflation of Collapsed Lung • Early Ligation of Pul. A. • CPAP (5~10cmH2O) to the Collapsed Lung • PEEP (5~10cmH2O) to the Ventilated Lung • Continuous insufflation of O2 • Change TV & RR 5. Alternatives to One-lung Ventilation -Adequate oxygenation 유지하는 것이 중요 -High frequency PPV & high frequency jet ventilation used

32. ANESTHESIA FOR LUNG RESECTIONpostoperative management 1. General Care • Early extubation : pul. Barotrauma와 pul. Infection 감소 (double lumen은 regular tube로 change) • Atelectasis에 의해 Postop hypoxemia & resp. acidosis 흔함 • Postop hrr. : chest tube drainage increase, hypotension, tachycardia, falling Hct. • Semi-upright position, supplement oxygen close monitoring

33. ANESTHESIA FOR LUNG RESECTIONpostoperative management 2. 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)

34. ANESTHESIA FOR LUNG RESECTIONpostoperative management 3. Postoperative Complications • Atelectasis : blood clots & thick secretion • Air leak from operative hemithorax - bronchopleural fistula - inadequate blood flow으로 인한 suture line의 necrosis • Herniation of heart into the hemithorax • Phrenic, vagus, Lt. recurrent laryngeal n. injury

35. SPECIAL CONSIDERATIONS FOR PATIENTS UNDERGOING LUNG RESECTION < Massive Pulmonary Hemorrhage> • Definition : 24시간 동안 tracheobroncial tree로부터 500~600ml 이상의 bleeding (모든 hemoptysis case의 1~2%정도) • 원인: TB, bronchiectasis, neoplasm, transbronchial biopsies • 치료: embolization, tamponade, laser coagulation -bleeding side lung을 dependent 쪽으로 lateral position 유지 • 이미 충분히 hypoxic 하므로 sedation은 불필요 → (만일 intubated state 면 coughing을 막기 위해 sedation이 helpful) • Intubation시에는 bleeding swallowing에 의한 full stomach임을 감안하여, awake 상태로 rapid sequence induction 시행 • Semiupright position maintained & cricoid pressure

36. 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 > • Primary pul. infection, obstruction, pul. Neoplasm 등에 의해 생기며 드물게 전신 감염의 혈행성 전이로 발생 • Isolating two lungs early to prevent soiling of healthy one with pus • Affected lung이 dependent position으로 되도록

37. SPECIAL CONSIDERATIONS FOR PATIENTS UNDERGOING LUNG RESECTION < Bronchopulmonary Fistula > • 원인 : Lung resection Rupture of pul. Abscess Pul. barotrauma Spontaneous rupture of bullae • 대부분은 conservative treat로 치료 • Conservative Tx. 실패 시 op. → recommend awake intubation with double lumen tube rapid sequence induction

38. ANESTHESIA FOR TRACHEAL RESECTION 1. Preoperative Considerations • Tracheal stenosis, tumor 있는 경우 • Flow-vol. loops로 obx.의 위치와 severity를 평가할 수 있다.

39. ANESTHESIA FOR TRACHEAL RESECTION 2. Anesthetic Considerations • Anticholinergics만 premedication 한다. • Lower tracheal resection시는 left radial a.에 cannulation하는 것이 좋다   (innominate artery가 compression될 수 있으므로) • Inhalation Agent으로 slow induction (with 100% O2) (Halo- & Sevo- : respiratory depression이 적고, airway 자극이 덜함) • Induction시에 spontaneous ventilation을 유지하며, muscle relaxant는 사용 안 한다. (muscle paralysis후에 complete airway obx.이 올 수 있다.)

40. 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.

41. ANESTHESIA FOR DIAGNOSTIC THORACIC PROCEDURES 1. Bronchoscopy • Flexible FOB • Rigid bronchoscopy : foreign body removal tracheal dilatation • 술기를 시행하는 operator와 airway를 공유 해야 하는 어려움이 있다. • Iv induction 후, potent inhalation anesthesia with 100% O2 with short or intermediate muscle relaxant. (propofol과 같은 total iv anesthetics도 유용)

42. ANESTHESIA FOR DIAGNOSTIC THORACIC PROCEDURES 2. Mediastinoscopy • Access to mediastinal LN • Establish Dx. or resectability intrathoracic malignancies • Cx. - vagal reflex bradycardia - excessivehrr. - Cb. ischemia - pneumothorax - air embolism - recurrent laryngeal n. damage 3. Bronchoalveolar lavage (BAL) • pt. with pulmonary alveolar proteinosis -indicated for severe hypoxemia or worsening dyspnea