Thoracic Anesthesia Introduction • Common Thoracic Surgeries – – – – – – – – – – – – – Lobectomy, pneumonectomy Wedge resection of lung lesions Chest wall resection Repair of pectus excavatum or carinatum Thoracoplasty Drainage of empyema Excision of mediastinal tumor Mediastinoscopy Video-assisted thoracoscopy surgery (VATS) Thymectomy Excision of blebs or bullae Lung-volume reduction surgery Lung Transplant Topics to be covered • Pre-operative evaluation • One Lung Ventilation – Double lumen tubes and bronchial blockers • • • • • • Intra-operative anesthetic management Potential Complications Hypoxic Pulmonary Vasoconstriction (HPV) Anesthetic Concerns Pain Management and post-operative course Further studies and the future of thoracic anesthesia Common Preoperative Evaluations • Monitor the patient’s ability to ventilate and oxygenate themselves – – – – Exercise Pulse ox monitoring Qualitative signs- chest rise, use of accessory muscles, auscultation Does the patient use oxygen at home? • Consider an Art-line for frequent ABG to monitor the oxygenation of the patient • Contraindications of double lumen tube placement: – an airway mass that may become dislodged or prevent passage of a tube – A known difficult airway – Dependence on ventilation of both lungs – RSI cases with risk of aspiration Diagnostic Studies and Pulmonary Function Tests (PFTs) • ABG Analysis • Spirometry – FVC/FEV1 • Split Lung Function and Ventilation:Perfusion Studies • Exercise Studies • Right Heart Function Evaluating Right Heart Function • Patients with a history of smoking and underlying COPD are at a greater risk of right heart failure secondary to pulmonary arterial hypertension • Congestive heart failure and cor pulmonale may be exacerbated after extensive lung resection surgery. • The criteria for inoperability includes: – Increase in mean PA pressure to > 35-40 mm Hg – Increase in PaCO2 to > 60 mm Hg – Decrease in PaO2 to < 45 mm Hg One Lung Ventilation • A procedure performed to provide independent ventilation to a single lung to prevent contralateral contamination, facilitate the surgery, or to allow selective ventilation. • Preop diagnosis: Wide range of operations including: – Lobectomy – Pneumonectomy – Wedge Resection • Common guideline: a surgery requires retraction of either lung Indications for the Procedure • Isolation to protect either lung – Hemorrhage within the trachea – Infectious pus, fluids, bacteria • Need to control ventilation aspects – Bronchial trauma – Bronchopleural fistula – Cyst (risk of rupture) • Surgical Exposure – Thoracic aortic aneurysm – Thoracoscopy – Esophageal surgery • Unilateral Lung Lavage • VATS (video-assisted thoracic surgery) Methods of One Lung Ventilation • Placement of a Double Lumen Tube • Placement of a Bronchial Blocker – Univent tube- built in bronchial blockers (disadvantage of this tube is the inability to ventilate when verifying placement with a FOB – Isolated Bronchial Blocker Double Lumen Tube Insertion and Verification of Placement • Video for Insertion: – https://www.youtube.co m/watch?v=JZkOiy4PXxg • Verification Methods: – Auscultation – Capnography – Observation of Chest Rise – Gold Standard: Fiberoptic Bronchoscope • Types of Double Lumen Tubes – Left sided DLT used most commonly Verification Techniques Bronchial Blocker Insertion • Video of Insertion : – https://www.youtube.c om/watch?v=mlS35eU UxqA • Verification of placement correlates with a double lumen tube Univent Endobronchial Tube Isolated Bronchial Blocker Anesthetic Management • Use mostly in General Anesthesia cases • Patient Positioning – Common Positions during One Lung Ventilation: Lateral Decubitus • Be aware of the physiological changes that proceed with this position • Always verify tube placement after repositioning • Use of Pressure Control Ventilation – Decreases the variation in peak airway pressures during surgical manipulation Effects of Positioning and Anesthesia on V/Q Anesthetic Management • Adequate Oxygenation – Prevention of Absorption Atelectasis – can be observed with increased FiO2 • closely observe FiO2 levels and use PEEP with large tidal volumes – Maintenance of CO2 levels – Verification of Tube placement – FiO2 of 0.25-0.50 to dilate the pulmonary vessels and provides adequate oxygenation to deflated dependent lung while avoiding absorption atelectasis and overuse of inhalational anesthetics – PEEP of 5 cmH2O to dependent lung – Large tidal volumes- 8-10 mL/kg (some use small tidal volumes of 4-6 ml/kg to avoid excessive movement of the deflated lung) – Adjust respiratory rate to maintain a PaCO2 = 40 mmHg – Avoid hypercapnia due to the hypoxic pulmonary vasoconstriction response – CPAP in the operative lung Complications • 2 Main Types of Complications that Correlate to the Tube – Malposition- hypoxemia and peaked airway pressures, obstruction of the trachea – Traumatic Damage- stiff tubing, forceful insertion , vocal cord rupture, arytenoid dislocation • Physiological Complications – – – – – Hypoxemia Decreased cardiac output which can lead to reduction in SvO2 Inability to isolate lung Increased pulmonary vascular resistance Airway resistance Anesthetic Management • Hypoxic Pulmonary Vasoconstriction Responseresponse of the lung to hypoxia which shunts pulmonary blood flow from areas of low oxygenation to areas of high oxygenation – Etiology: Vasoactive redox sensor that responds to hypoxia and activates the mitochondrial electron transport chain. This chain generates diffusion of a reactive oxygen species that regulates the voltage gated potassium and calcium channels. The activation of the calcium channel results in calcium influx and vasoconstriction. • This response reduces ventilation/perfusion mismatch when hypoxia is present. • https://www.youtube.com/watch?v=SJ1gu_WRx5o HPV Schematics Anesthetic Concerns • Management of Hypoxic Pulmonary Vasoconstriction – Inhibited by: • • • • • Increased levels of inhaled anesthetics Vasodilators Hypocarbia Metabolic alkalemia Indirectly by volume overload (vasodilation), hypothermia (low metabolic state), and thromboembolism – Can be improved with: • Nitric Oxide use- potent vasodilator by decreasing levels of calcium • Prostacyclin produces vasodilation in pulmonary beds and promotes release of nitric oxide from endothelial cells • Adequate Oxygenation Anesthetic Concerns • Patients requiring pleurodesis may be exposed to sclerosing agents including: • Tetracycline, Talc, and Bleomycin – Side effects of these medications include fever and chest pain – Bleomycin is associated with pulmonary toxicity that is exacerbated with high FiO2 – need to maintain low FiO2 (<0.3) in these patients Anesthetic Concerns • Risk of Pneumothorax, pneumomediastinum, subcutaneous air. – Nitrous is contraindicated (in a closed gas space N2O can enter 34x more rapidly than N2 can escape) – Inspiratory pressures < 25 cm H20 will decrease the risk of pneumothorax Anesthetic Concerns • Pain management – Effective analgesia is important to allow the patient to cough, breath deeply, and adequately heal. – Consider using an epidural (midthoracic region – T7) with opioids to manage the pain with large open cases. This will also help to decrease postoperative pulmonary complications as well as postoperative hospital stay. • Paravertebral analgesia (injected into paravertebral space located directly lateral to spinal nerves) can interfere less with postoperative lung function than epidural analgesia Thoracic Paravertebral Block • Inject local alongside thoracic vertebra close to where the spinal nerves emerge from intervertebral foramen. (closer to vertebral column) • Indications – Thoracotomy – VATS – Fractured ribs Thoracic Paravertebral • Wedge shaped space located on either side of vertebral column • Ipsilateral somatic and sympathetic nerve blockade • Extends to intercostal space laterally and epidural space medially Thoracic Paravertebral Block • 2.5 cm lateral to midline (compared to 6-8 cm) – Edge of transverse process of vertebra • Find Transverse Process – Walk off above – Loss of resistance • Within 1 to 1.5 cm of transverse process Intercostal Nerve Block • Blocks Ipsilateral sensory and motor fibers • Need to perform blockade of two dermatomes above incision and two levels below incision • Does not block visceral pain • Does not provide adequate coverage for intraoperative anesthesia Risks • Pneumothorax – Below 1% – Advancement of needle beyond 3mm increases risk • Local Anesthetic Toxicity – Greatest absorption – Only 3-5mL needed per segment • Hematoma • Nerve damage • Spinal Anesthesia – Dural sheath can extend up to 8 cm laterally • Blocked 6-8 cm from the spinous processes – Angle of the ribs – Subcostal grove is at it’s widest – Rib is superficial and easy to palpate – Ensures coverage of lateral cutaneous nerve – Catheter can be placed – May be difficulty above T7 because of scapulae Further Studies Non-intubated video-assisted thoracoscopic lung resections: the future of thoracic surgery? • European Journal of Cardio-Thoracic Surgery, April 19, 2015 • Most pulmonary resections can now be performed minimally invasively • Non-intubated thoracoscopic approach has been adapted with minimally invasive surgeries – VATS • Minimizing the adverse effects of tracheal intubation and General Anesthesia – – – – – Intubation related airway trauma Ventilation-induced lung injury Prolonged neuromuscular blockade PONV Blunting of HPV response with general anesthesia References • • • • • • • • http://www.openanesthesia.org/One_Lung_Ventilation https://www.bu.edu/.../oneLungVentilation_122506.pp... http://www.slideshare.net/dangthanhtuan/one-lung-ventilation Longnecker, D. (2012). Thoracic Anesthesia. In Anesthesiology (2nd ed., pp. 963-974). McGraw-Hill. Jaffe, R. (2014). Thoracic Surgery. In Anesthesiologist's Manual of Surgical Procedures (5th ed., pp. 288289). Philadelphia: Wolters Kluwer Health. Gonzalez-Rivas, D., C Bonome, E. Fieira, H Aymerich, R Fernandez, M Delgado, L Mendez, and M de la Torre. Non-intubated video-assisted thoracoscopic lung resections: the future of thoracic surgery? European Journal of Cardio-Thoracic Surgery. 2015; 1-11. Stanford Anesthesia Cognitive Aid Group. Emergency Manual. 2014. The New York School of Regional Anesthesia. 2016. http://www.nysora.com.
