Bronchial Blockers

•  Bronchial blockers: May require longer to position & more intraop repositioning

• Univent tracheal tube (provides CPAP, but cannot ventilate while isolating the lung)

• Fogarty catheter (sm. size makes useful in pedi cases)

• No lumen for deflation, CPAP, or suction

• Wire-guided endobronchial blocker (WEB)

• Small lumen for deflation, CPAP, or suction

• Insertion loop: One-time use

Physiology of One-lung Ventilation

•  One-lung ventilation in lateral position

• Gravity causes ↑ blood flow to dependent (bottom) lung

• Pulmonary shunt ↓ as dependent lung is being oxygenated

•  Lateral positioning with open chest

• ↑ blood flow to dependent lung

• ↓ effective compliance in dependent lung

• ↓ FRC

• Altered V./Q. (↑ perfusion, ↓ ventilation-dependent lung)

↓ oxygenation, ↓ CO₂ elimination

•  Hypoxic pulmonary vasoconstriction (HPV)

• Vasoconstriction of pulm arteries in presence of hypoxia → redirecting blood to alveoli with higher O₂ tension

• Improves V./Q. matching → better gas exchange

• Inhibited by vasodilators (e.g., nitroprusside, nitroglycerine) alkalemia, hypocarbia, volatile anesthetics, PEEP

•  Risk of hypoxemia in 1 lung ventilation

• V./Q. impairment

• ↓ HPV

• Worse typically at 10–30 min (absorption atelectasis—remaining alveolar O₂ depleted)

Anesthesia with One Lung

•  Invasive monitoring

• Arterial line—preferably dependent radial artery

• CVP (± for uncomplicated VATS/wedge/lobe in healthy pt)

• Pulmonary artery catheterization in selected pts

→ Monitor PA, P_cw for left heart filling pressures

→ PA catheter usually floats to the R side

→ Often not in best monitoring position (i.e., not in West zone 3)

Risks: Dysrhythmias, PA rupture

No proven improvement in outcomes with routine use

•  Fiberscopic verification tube/blocker placement

•  Tidal volume 6–8 mL/kg; plateau pressure <25 cm H₂O; peak pressure <35 cm H₂O

• Smaller TV ↑ risk atelectasis

• Larger TV ↑ shunting to nonventilated lung, ↑ risk barotraumas

•  ↑ ventilation rate modestly (10%) to allow EtCO₂ 35 mm Hg

•  Oxygen 100%

• Maximal PaO₂

• Possible absorption atelectasis

•  Limit time on 1-lung ventilation

•  ↑ incidence of hypoxemia with:

• Right lung deflation

• Supine position

• Normal preop spirometry (no intrinsic PEEP)

•  Management of hypoxemia

• Recheck proper tube position with fiberscope (see later)

• CPAP 5–10 cm H₂O to nonventilated lung

<5 cm H₂O generally ineffective

>10 cm H₂O may reinflate nonventilated lung

• Consider PEEP to ventilated lung

May worsen hypoxemia via ↑ blood flow to nonventilated lung

• Return to 2-lung ventilation if serious irreversible hypoxemia

• For pneumonectomy—consider early operative ligation of pulmonary artery

ANESTHETIC TECHNIQUES—SPECIFIC SURGICAL PROCEDURES

Mediastinoscopy

•  Preop evaluation

• Airway: Mass effects on trachea, great vessels

• History: CV prob, stroke, SVC syndrome, Lambert–Eaton syndrome

•  Complications

• Hemorrhage, pneumothorax, chylothorax, recurrent laryngeal nerve injury, air embolization

•  Anesthetic management

• General anesthesia most common

• Vascular access

→ Large bore IVs

→ Arterial line in left radial (right radial subject to innominate artery compression by mediastinoscope)

• Avoid nitrous oxide

• Muscle relaxation

→ Movement ↑ risk of surgical trauma

→ Cough/strain ↑ thoracic venous engorgement

→ Spontaneous ventilation may ↑ risk air embolism

•  Postop—must check chest X-ray

Video-assisted Thoracic Surgery (VATS)

•  Preop evaluation

• Discuss potential for open thoracotomy

•  Complications

• Bleeding, lung injury (air leak)

•  Anesthetic management

• General anesthesia most common

• Large-bore IV (consider CVP) access

• Arterial line

• Lung separation (see lung isolation section above)

• Consider slightly lower TV (e.g., 7–8 mL/kg) to ↓ mediastinal shift (improves operating conditions)

• ↑ Ventilation rate 10% (get CO₂ absorption with insufflation)

• Muscle relaxation (see “Mediastinoscopy,” above)

• Consider neuraxial anesthetic if ↑ likelihood of conversion to open thoracotomy

•  Postop—must check chest X-ray

Pneumonectomy

•  Preop evaluation

• See “PFTs/Evaluation of Lung Resectability,” above

• ↑ risk of morbidity with right vs. left pneumonectomy, trauma, massive hemoptysis, history of cardiac disease, >10% preop weight loss

• Optimize treatment of existing pulmonary/cardiac disease

• Encourage smoking cessation

•  Complications

• Bleeding, airway (stump) leak, cardiac dysrhythmias (consider role of β-blocker), cardiac herniation through pericardial defect, pulmonary edema, myocardial infarction, intracardiac shunt (can get ↑ R heart pressure, shunting via PFO)

•  Anesthetic management

• Arterial catheter, central venous line

• Consider PA catheter

→ May not easily float to nonoperative side

→ Readings may not be reliable (tip not in West zone III)

→ May interfere with surgical procedure

• Airway

→ DLT to nonoperative side or bronchial blocker

→ Risk of intraop dislodgement with either technique

→ Risk of bronchial stump damage with manipulations

• Muscle relaxation

• Limit intraop fluids

• Postop analgesia options

→ Neuraxial opioid ± local anesthetic

→ Intercostal nerve blocks

→ Intrapleural catheter (risk of local anesthetic toxicity)

→ Systemic opioids (transition to IV PCA as tolerated)

Mediastinal Mass Considerations

•  Preop eval

• ↑ Risk of tracheobroncheal obstruction with:

→ Orthopnea

→ Large airway compression on imaging

→ Flattened expiratory limb of flow-volume loop on PFTs

• Eval for evidence of superior vena cava syndrome

→ Upper extremity/facial edema (may indicate airway edema)

→ Dilated upper extremity veins

→ Headache, CNS changes

→ Consider preop steroid, diuretic, elevation of head of bed

• History syncope with position or Valsalva suggests

→ Cardiac/PA compression with hypotension

→ Critical tracheobronchial obstruction

→ Consider preop echo to eval for compression

• Consider preop biopsy/treatment to shrink mass (if severe airway/cardiovascular compression)

•  Complications

• Acute tracheobronchial compression intraop

→ Highest risk is on transition to positive-pressure ventilation

• Acute cardiac/PA compression with severe hypotension

• Bleeding (esp with SVC syndrome due to venous engorgement)

•  Anesthetic management

• Arterial access preinduction

• Large bore/central venous access

• Consider standby cardiopulmonary bypass (femoral) if airway or cardiovascular compression by mass

• Rigid bronchoscope available

• If SVC syndrome:

Consider lower extremity vascular access (more reliable drug/fluid delivery)

Avoid jugular or subclavian lines

• Consider spontaneously breathing fiberscopic exam/intubation if significant airway compression

• Initiate slow, controlled induction

Controlled transition from spontaneous ventilation to positive pressure

Short-duration relaxant desirable to facilitate tracheal intubation

If airway obstruction occurs:

• Attempt lateral positioning to move mass

• Resume spontaneous ventilation if possible

• Attempt to pass tracheal tube beyond obstruction carefully (risk hemorrhage)

• Attempt rigid bronchoscopy to open airway

• Consider cardiopulmonary bypass (femoral)

Smooth emergence & extubation

Cough/straining may worsen airway collapse

May ↑ bleeding (esp if SVC syndrome)

Esophagectomy

•  Preop eval

• Nutritional status (↓ serum albumin, total protein)

• Dysphagia (reflux, risk of chronic aspiration)

• Prior chemo/radiation therapy

• Risk for cardiac dysrhythmias, esp supraventricular (consider prophylactic digoxin/β-blocker)

• Consider epidural placement

•  Complications

• Gastroesophageal reflux, esophageal leak, respiratory failure, hypotension, cardiac dysrhythmias

•  Anesthetic management

• Arterial line, consider central venous line

• Lung isolation for thoracotomy approaches

• Avoid nitrous oxide (expands bowel gas, need high FiO₂ with 1-LV)

• Limit fluids

• ↑ Fluids associated with ↑ incidence pulmonary complications

• Avoid vasopressors

• Intraop use or hypotension associated with ↑ incidence GI anastomotic leak

• Consider ↓ drug dosages if pt has ↓ serum albumin

• Consider cricoid pressure at induction

→ May ↓ lower esophageal sphincter tone

→ May impede use intubation LMA

• Monitor glucose closely (esp if on TPN)

• Communicate with surgeon regarding esophageal manipulations (e.g., NG tube, esophageal bougie)

• Intraop hypotension: May be from hypovolemia, surgical compression of heart or great vessels, bleeding

• If postop mechanical ventilation planned

→ Change to standard endotracheal tube at completion of surgery