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Anesthesia for thoracic surgery

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					Ch24. Anesthesia for thoracic
         surgery

                    전공의 1년
                     노지성




                                1
         PHYSIOLOSIC CONSIDERATION
                 DURING THORACIC ANESTHESIA

1.    마취에 있어서 특별한 physiologic set을 요구한다.
     ①    lat. decubitus position, open pneumo thorax, one-lung
          ventilation등
2.    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.
       a. 즉, perfusion은 dependent part(lower)에 잘 되는 반면,
            ventilation은 upper lung에서 더 잘 이루어져 V/Q mismatch가
            심화되어 hypoxemia의 risk가 커진다.
     ① The Awake State
       a. V/Q matching preserved → lower lung > upper lung
       b. 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 ↑
 PHYSIOLOSIC CONSIDERATION
          DURING THORACIC ANESTHESIA

②  Induction of Anesthesia
  a. functional residual capacity (FRC) ↓
  b. p-v curve에서 upper lung의 compliance가 more favor
  c. 결과적으로 upper lung이 ventilation이 더 잘되!
       →V/Q mismatching이 초래된다.
③ Positive Pressure Ventilation
  a. compliance의 증가로 upper lung이 CPPV이 더 잘된다.
       →muscle paralysis는 abd. contents를 rise up시켜 lower
           hemithorax를 더욱 restrict시킨다.
  b. upper lung을 open시키면 compliance는 더 증가되어 V/Q
       mismatching이 심화되어 hypoxemia를 더욱 조장한다.
         PHYSIOLOSIC CONSIDERATION
               DURING THORACIC ANESTHESIA

1.    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
     ① Mediastinal Shift
       a. Lateral position에서 spontaneous ventilation시에
           inspiration시 아랫쪽 lung에서는 pleural pressure가
           negative pressure가 되어 mediastinum이 downward
           shift(insp.) & upward shift(expi.) f-24-3
       b. *paradoxical respiration
       c. open pneumothorax시 to-and-fro gas flow between
           dependent &nondependent lung
       d. inspiration시 pneumothorax ↑ →upper lung에서 carina를
           통과하여 gas flow가 dependent lung으로, expiration시는
           reverse(upper lung으로)
         PHYSIOLOSIC CONSIDERATION
                   DURING THORACIC ANESTHESIA

1.   ONE-LUNG VENTILATION
     ①    collapse된 lung은 perfusion은 계속되면서 ventilation은 안되기 때문에 right-to-left
          intrapulmonary shunt가 발생한다.(20~30%)
     ②    unoxygenated blood (from upper lung)와 oxygenated blood(dependent lung)가 섞여
          PA-a (alveolar-to-arterial) O2 gradient를 widen →hypoxemia
     ③    다행히도 hypoxic pulmonary vasoconstriction(HPV)과 surgical compression이
          upper lung으로의 blood flow를 감소시킨다.
     ④    *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
     ⑤    *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
     ⑥    참고로 arterial CO2 tension은 two-lung ventilation과 별반 차이를 보이지 않는다.
          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
          TECHNIQUES FOR ONE-LUNG
                VENTILATION
1.   DOUBLE-LUMEN ENDOBRONCHIAL TUBES
     ①   <double-lumen tube의 장점>
         1.ease of placement
         2.ability of ventilating of either or both lung
         3.ability of suction either lung
     ②   <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
     ③   두개의 cuff를 모두 inflation시켜 한쪽 lung은 collapse시키고, 다른
         쪽 lung으로만 ventilation이 되게 하는 원리.
     ④   양쪽 bronchus의 anatomical difference 때문에 Rt & Lt가 각각
         따로 design되어 있다.
     ⑤   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.
           TECHNIQUES FOR ONE-LUNG
                 VENTILATION
1.   Anatomic Considerations
     ①   trachea : 11~13cm(cricoid cartilage(C6) ~ sternomanubrial
         joint(T5))
     ②   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.
     ③   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.
     ④   어떤 tube들은 carinal hook를 가지고 있는데,(eg, Carlens and
         White) tube placing의 어려움 때문에 많이 사용하지 않는다.
             TECHNIQUES FOR ONE-LUNG
                   VENTILATION
1.    Placement of Double-Lumen Tubes
     ①    distal curvature가 앞쪽으로 concave하게 진행.
     ②    tip이 larynx를 통과하면 intubation할 bronchus쪽으로 90〫           rotation을 시킨 후, 저항이 느껴질 때 까지
          진행시킨다.(보통 이때의 길이는 teeth에서 29cm 정도가 된다.
     ③    confirm은 flexible FOB를 사용하여 눈으로 직접 확인한다.
     ④    문제가 생기면 “tube exchanger”를 사용하여 smaller regular tube로 즉시 tube change를 한다.
     ⑤    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.
     ⑥    optimal하게 place되었다면 bronchial cuff를 inflation시킨 후 breathing sound를 들어보면,
          endobronchial ventilation을 시켰을 때 새는 소리가 나지 않는다.
     ⑦    position change 후에도 breathing sound 확인하는 것을 잊지 말자!
     ⑧    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.
     ⑨    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.
     ⑩    원치 않게 wrong bronchus로 intubation 되었다면, flexible FOB를 bronchial lumen으로 집어넣어
          scope guide하에 repositioning 할 수 있다.
     11   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
               TECHNIQUES FOR ONE-LUNG
                     VENTILATION
1.       SINGLE-LUMEN ENDOTRACHEAL TUBES WITH A
         BRONCHIAL BLOCKER
     ①     bronchial blockers are inflatable device passed alongside or
           through a single-lumen ETT
     ②     retractable bronchial blocker를 위한 side channel이 있는 single
           lumen ETT가 상업적으로 많이 사용된다(eg, Univent tube)
     ③     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.
     ④     inflatable catheter(Forgarty)가 bronchial blocker로써 regular
           ETT와 짝을 이루어 사용할 수 있다.
           →isolated lung의 suction이나 ventilation이 불가능.
     ⑤     bronchial blocker는 pediatric patients의 one-lung ventilation이나
           성인에서의 tamponating endobronchial bleeding의 anesthesia에
           유용하다.
2.       SINGLE-LUMEN ENDOBRONCHIAL TUBES
     ①     rarely used
     ANESTHESIA FOR LUNG RESECTION
                        PREOPERATIVE CONSIDERATIONS

1.   1.Tumors
2.   -benign : hamartomas, bronchial adenoma
3.    malignant : small cell("oat cell")ca., non small cell ca. (epidermoid, adenocarcinomas,
     large cell ca.)
4.    Clinical Menifestation
5.    -Sx : cough, hemoptysis, dyspnea, wheezing, wt. loss, fever or         productive sputum,
     chest pain(pleural extension),
6.     hoarsness(mediastinal involve),Horner syn.(sympathetic
     chain        involve) dysphagia(esophagus compression),pancoast
     synd.(sup.      sulcus involve)
7.     meta : brain, bone, liver, and adrenal gland
8.    -paraneoplastic syndrome : ectopic hormone production &               immunologic cross-
     reactivity between the tumor and normal tissue
9.     (Cushing synd., hyponatremia, hypercalcemia,Lambert-Eaton synd.등)
      ANESTHESIA FOR LUNG RESECTION
                  PREOPERATIVE CONSIDERATIONS
1.    Treatment
2.     -surgery : choice of curative tx.(LN involve와 distant meta가 없다면)
3.     -resectability & operability : resectability determined by anatomic     stage of
      tumor, operability depend on extent of procedure &           physiologic status
4.     Operative Criteria for Pneumonectomy
5.     -measure PFT : directly related to op risk
6.     -m/c used criteria for operability
7.     →postoperative FEV1 greater than 800ml
8.       postoperative FEV1 =
9.     %blood flow to remaining lung × total FEV1
10.
      ANESTHESIA FOR LUNG RESECTION
                 PREOPERATIVE CONSIDERATIONS
1.    2.Infection
2.    -may present at solitary nodule or
3.     cavitary lesion(necrotizing pneumonitis)
4.     → empyema, massive hemoptysis
5.    -bacteria(anaerobies, mycoplasma, norcadia)
6.     fungi(histoplasma, coccidioides,..)
7.

8.    3.Bronchiectasis
9.    -dilatation of bronchi : severe or reccurent infl. & obstruction of bronchi
10.   -resection Ix. : massive hemoptysis, failed conservative measure,      disease
      localized
     ANESTHESIA FOR LUNG RESECTION
                ANESTHETIC CONSIDERATIONS

1.   1.Preoperative Management
2.   -smokong is risk factor for COPD & coronary artery disease.
3.   -echocardiography : baseline cardiac function assess
4.    dobutamine stress echo : detect occult coronary a. disease
5.   -tracheal, bronchial deviation : airway compression
6.   -high risk pt. complication reduce
7.    Premedication
8.   -anticholinergics : ↓ copious secretion
      ANESTHESIA FOR LUNG RESECTION
                        ANESTHETIC CONSIDERATIONS
1.    2.Intraoperative Management
2.    Preparation
3.    -various size single & double lumen tubes, flexible FOB, tube       exchanger, CPAP delivery system,
      anesthesia circuit adaptor prepare
4.    Venous Access
5.    -at least one large-bore IV line(14~16G)
6.    Monitoring
7.    -direct a. pressure monitoring : one lung anesthesia, large tumor     resection
8.    -CVP : net effect of venous capacitance, blood volume, rt. ventricular function
9.    -pul. a. catheterization : pul HTN, cor pulmonale, lt. ventricular  dysfunction
10.   Induction of Anesthesia
11.   -adequate preoxygenation, IV barbiturate is used for most pt.
12.   -peep prevent atelectasis, paradoxical mediastinal shift
13.   Positioning
14.   -most lung resections are performed via post. thoracotomy with the pt. in the lat. decubitus position
      ANESTHESIA FOR LUNG RESECTION
          maintenace of anesthesia
1.    -halogenated agent(halo, isoflu, sevoflu, or desflu) with opioid is   prefer
2.    -halogenated agent의 장점
3.    ①potent dose related bronchodilation
4.    ②depression of airway reflexes
5.    ③ability to use a high O2 concentration
6.    ④capacity for relatively rapid adjustment in anesthetic depth
7.    ⑤minimal effects on HPV
8.    -opioid의 장점
9.    ①minimal hemodynamic effects
10.   ②depression of airway reflexes
11.   ③residual postop. analgesia
12.   -N2O not used : decrease FiO2
13.   -IV fluid restricted in pul. restriction pt.
14.   Management of One-Lung Ventilation
15.   -greatest risk : hypoxemia → 100% O2 use
16.   -if peak pressure rise(>30cm H2O)
17.    : tidal volume reduce 6~10ml/kg
18.     & increase rate
19.   Alternatives to One-lung Ventilation
20.   -adequate oxygenation be maintained
21.   -high frequency positive pressure ventilation & high frequency jet    ventilation used
      ANESTHESIA FOR LUNG RESECTION
                                postoperative management
1.    General Care
2.    -most pt. are extubated early : decrease risk of pul. barotrauma, pul. infection(double lumen은 regular
      tube로 change)
3.    -posop hypoxemia & resp. acidosis commom → cause mainly by atelectasis
4.    -postop hrr : chest tube drainage increase, hypotension, tachycardia
5.    falling Hct.
6.    -semiupright posion, supplement oxygen close monitoring
7.    Postoperative Analgesia
8.    -IV opioids small dose superior to IM large dose
9.    -0.5% ropivacaine inject above & below two levels of thoracotomy incision
10.   -cryoanalgesia, epidural ( morphine 5~7mg/10~15ml saline)
11.   Postoperative Complications
12.   -atelectasis : blood clots & thick secretion
13.   airleak from operative hemithorax : bronchopleural fistula inadequate blood flow or inf. torsion of lobe or
      segment
14.   herniation of heart into the hemithorax
15.   phrenic, vagus, lt. recurrent laryngeal n. injury
         SPECIAL CONSIDERATIONS FOR PATIENTS
                 UNDERGOING LUNG RESECTION

1.   Massive Pulmonary Hemorrhage
     ①   -definition : 500~600ml< from tracheobronchial tree within 24 hrs.(모든
         hemoptysis case의 1~2%정도)
     ②   -result of TB, bronchiectasis, neoplasm, transbronchial biopsies
     ③   -embolization, tamponade, laser coagulation
     ④   -bleeding side lung을 dependent 쪽으로 lateral position유지
     ⑤     →bleeding tamponade
     ⑥   -sedation은 불필요. → 이미 충분히 hypoxic이니까. (만일 intubated
         state 면 coughing을 막기위해 sedation이 helpful.)
     ⑦   -intubation시에는 bleeding swallowing에 의한 full stomach임을
     ⑧    감안하여, awake 상태로 rapid sequence induction 시행.
     ⑨   -semiupright position maintained & cricoid pressure
     ⑩   -airway의 large blood clot을 suction하는데, sodium bicarbonate가
         유용 하다.
          SPECIAL CONSIDERATIONS FOR PATIENTS
              UNDERGOING LUNG RESECTION

1.    Pulmonary Cysts & Bullae
     ①    -congenital   or result from emphysema
     ②    -rupture of air cavity → tension pneumothorax
     ③    -N2O cIx.(it can expand air space & rupture)
     ④    Lung Abscess
     ⑤    -result from primary pul. infection, obstructing pul. neoplasm,
          드물게 전신 감염의 혈행성 전이.
     ⑥    -isolating two lungs early to prevent soiling of healthy one with pus
     ⑦    -affected lung in dependent position
     ⑧    Bronchopulmonary Fistula
     ⑨    -result following lung resection, rupture of pul. abscess,
          pul.         barotrauma, spontaneous rupture of bullae
     ⑩    -대부분은 conservative treat로 치료됨.
     11   conservative Tx. 실패시 op. → recommend awake intubation with double
          lumen tube wide rapid sequence induction
                  ANESTHESIA FOR
                            tracheal resection

1.   Preoperative Considerations
     ①   -performed for tracheal stenosis, tumor
     ②   -flow-vol. loops confirms the location of obs. & evaluating
         severity
2.   Anesthetic Considerations
     ①   -anticholinergics만 premedi.
     ②   -lower tracheal resection시는 left radial a.에 canulation하는 것이
         좋다 (innominate artery가 compression될 수 있으므로)
     ③   -halothane으로 slow induction.(respiratory depression이 적고,
         airway 자극이 덜하므로.)
     ④   -induction시에 spontaneous ventilation을 유지하며, muscle
         relaxant는 사용 안 한다.(muscle paralysis후에 complete airway
         obs.가 올수 있다.)
3.
         ANESTHESIA FOR
     THORACOSCOPIC SURGERY
1.   -diagnostic & treatmental procedure
2.   -lung biopsy, segmental & lobar resection, pleurodesis,
     esophageal procedure, pericardectomy
3.   -3개 또는 그 이상의 small incision을 통해 시술하며,
     position은 lat.     decubitus position. anesthesia는 다른 open
     procedure에 준해서
4.    시행한다.
                                               ANESTHESIA FOR
             DIAGNOSTIC THORACIC PROCEDURES
1.        Bronchoscopy
     ①          -flexible FOB (discussed already)
     ②          -rigid bronchoscopy : foreign body removal, tracheal dilatation under general anesthesia
     ③          -술기를 시행하는 operator와 airway를 공유해야하는 어려움이 있다.
     ④           (그러나 보통 5~10분정도의 short procedure.)
     ⑤          -iv induction시에 potent inhalation anesthesia with 100% O2 with short or intermediate muscle relaxant.(propofol과 같은 total iv
                anesthetics도 유용)
     ⑥          -3 techniques
     ⑦           ①apneic oxygenation with a small catheter alongside
     ⑧             the bronchoscope
     ⑨           ②conventional ventilation through the side arm of
     ⑩             ventilatory bronchoscope
     11          ③high frequency ventilation through injector type bronchoscope
2.        Mediastinoscopy
     ①          -access to mediastinal LN &
     ②           establish Dx. or resectability intrathoracic malignancies
     ③          -Cx. : ①vagally reflex bradycardia ②excercise hrr. ③cb ischemia
     ④               ④pneumothorax ⑤air embolism ⑥recurrent laryngeal n. damage
     ⑤          Bronchoalveolar lavage(BAL)
     ⑥          -pt. with pulmonary alveolar proteinosis
3.        -indicated for severe hypoxemia or worsening dyspnea

				
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