FOR THORACIC SURGERY



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, Pcw 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


Only gold members can continue reading. Log In or Register to continue

Aug 28, 2016 | Posted by in ANESTHESIA | Comments Off on FOR THORACIC SURGERY

Full access? Get Clinical Tree

Get Clinical Tree app for offline access