Anesthesia for toracic surgery


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Anesthesia for toracic surgery

  1. 1. THORACIC ANESTHESIA • Anesthesia for thoracic surgery requires careful preoperative evaluation to identify patients liable to develop post operative morbidity especially the need for continued mechanical ventilation • Pulmonary function tests and ABG may be useful to identify at risk patients
  2. 2. THORACIC ANESTHESIA • Thoracic anesthesia presents a unique set of physiologic problems: 1)Lateral decubitus position 2)The open pneumothorax 3)One lung ventilation • These physiologic changes requires careful attention of the anesthetist to avoid serious complications
  3. 3. THORACIC ANESTHESIA 1.1. Lateral position:Lateral position: • It provides optimal access for most thoracic procedures • Unfortunately this position alters the normal ventilation /perfusion relationship ( V/Q ).These derangements are further accentuated by : *induction of anesthesia *muscle paralysis *opening the chest *surgical retraction *initiation of mechanical ventilation
  4. 4. THORACIC ANESTHESIA • Although perfusion continues to favor the lower lung, ventilation favors the upper lung This mismatch markedly increase the risk of hypoxia • Also induction of G.A decreases FRC and moves the lower lung( perfused) to a less compliant part of the compliance curve • Moreover PPV favors the upper lung as it is more compliant
  5. 5. THORACIC ANESTHESIA • All these effects worsen V/Q mismatching and predispose to hypoxia 2. The Open PneumothoraxThe Open Pneumothorax : • The lungs are kept expanded by the negative pleural pressure .When one side of the chest is opened the –ve pleural pressure is lost and the lung is collapsed • Spontaneous ventilation with open pneumothorax in the lateral position results in paradoxical respiration & mediastinal shift
  6. 6. THORACIC ANESTHESIA • These two effects can cause progressive hypoxia and hypercapnia but fortunately these can be overcomed by the use of PPV 3. OneOne Lung Ventilation:Lung Ventilation: • Intentional collapse of the lung on the operative side greatly facilitates most thoracic procedures but complicates anesthetic management • The collapsed lung continues to be perfused and no longer ventilated
  7. 7. THORACIC ANESTHESIA • So the patient develops RT_LT intrapulmonary shunt hypoxia • Mixing of oxygenated blood from the ventilated lung and unoxygenated blood from the collapsed lung widens alveolar to arterial gradient hypoxia • But fortunately the blood flow to the nonventilated lung is decreased by hypoxic pulmonary vasoconstriction and surgical compression of the upper lung
  8. 8. THORACIC ANESTHESIA • Techniques for one lung ventilation: 1. Use of double lumen EBT 2. Use of single lumen ET + bronchial blocker 3. Use of single lumen EBT • Double lumen endobronchial tube is often used
  10. 10. THORACIC ANESTHESIA • Double lumen endobronchial tubes: The principal advantage of double lumen tubes are relative ease of placement, the ability of ventilating either one or both lungs, the ability to suction either lung Name Bronchus Carinal hook CARLENS LEFT YES ROBERT-SHAW LEFT -RIGHT NO WHITE RIGHT YES
  11. 11. THORACIC ANESTHESIA • Placement of double lumen tubes (DLT): 1. Laryngoscopy with a curved blade 2. The DLT is passed with the distal curvature ant. 3. After the tip enters the larynx, the tube is rotated 90 degrees to the side to be intubated 4. The tube is advanced till resistance is felt, the average length is about 29 cm at the teeth 5. The tube position is established using a preset protocol and confirmed by flexible fiberoptic bronchoscopy
  12. 12. THORACIC ANESTHESIA • Protocol for LT side DLT placement: 1. Inflate the tracheal cuff (5-10 ml) 2. Check for bilateral breath sounds.Unilateral sounds indicate that the tube is so far, the tracheal lumen is endobronchial {withdraw the tube little up } 3. Inflate the bronchial cuff (1-2 ml) 4. Clamp the tracheal lumen 5. Check for LT. side breath sounds: a)persistence RT side .... Advance the tube b)unilateral RT.... Incorrect entry into RT bronchus 6. Unclamp tracheal &clamp bronchial....diminished breath sound on the RT {advance the tube }
  13. 13. THORACIC ANESTHESIA • After clamping of tracheal lumen, TV is usually set to 10ml/kg and the RR is increased by20% to maintain MV and PCO2 • Complications of DLT : 1. Hypoxia due tube malplacement or occlusion 2. Traumatic laryngitis 3. Tracheobronchial rupture due to overinflation of the bronchial cuff
  14. 14. THORACIC ANESTHESIA • The majority of patients undergoing thoracic surgery have underlying lung disease • Specific preoperative findings that make postoperative pulmonary complications likely include: dyspnea, cough ,sputum production, wheezing ,cigarette smoking, obesity, recent RTI and advanced age • The principle goal of preoperative evaluation is to identify patients at risk and to institute good preoperative therapy
  15. 15. THORACIC ANESTHESIA • Preoperative prophylactic measures Measures Result Cessation of smoking HbCO2 decreases in 12-24h so more O2 is available Treat pulmonary infections Select antibiotics according to culture and sensitivity Treat bronchospasm Beta-2 agonists Thin and mobilize secretions Hydration and chest percussion
  16. 16. THORACIC ANESTHESIA • Pulmonary function tests: • Pulmonary function tests are helpful in identifying patients at risk of developing pulmonary complications • In addition to PFT, ABG may be measured in patients with sever dyspnea and exercise intolerance • The simplest and most informative test is the FEV1, VC and analysis of the flow volume curves
  17. 17. THORACIC ANESTHESIA • The risk of postoperative pulmonary complications is increased when: 1. FEV1 < 2 L 2. Ratio of FEV1/FVC < 0.5 3. VC < 15ml/kg 4. Presence of arterial hypoxemia &/or hypercarpia • PFT & ABG should be repeated after antibiotic and bronchodilator therapy to confirm response to therapy
  19. 19. PREOPERATIVE MANAGMENTPREOPERATIVE MANAGMENT 1. Smoking increases the risk of COPD and coronary artery disease. Echo is very useful for assessing the cardiac function 2. Patients with tumors should be evaluated for local extension of the tumor( tracheal or bronchial) and paraneoplastic syndrome 3. Prophylactic digitalis especially in resection of pulmonary tissues
  20. 20. PREMEDICATIONPREMEDICATION • Patients with moderate to sever respiratory compromise should receive little or no premedication • Anticholinergics are very useful in reducing secretions and improve visualization during attempts of repeated Laryngoscopy and fiberoptic bronchoscopy
  21. 21. THORACIC ANESTHESIA 1)1) Preparation:Preparation: • The frequent presence of poor pulmonary reserve ,anatomic abnormalities or compromise of the airway ,and the need for one lung ventilation predispose these patients to rapid hypoxemia • A clear plan to deal with these difficults is necessary • Multiple single and double tubes should be available, fiberoptic bronchoscope should be available
  22. 22. THORACIC ANESTHESIA • When epidural catheter is considered to be placed it should be placed before induction of anesthesia to offer patient cooperation and decrease the incidence of neurological complications 2) Venous access:2) Venous access: • At least 2 large iv canula( 14-16 g) is mandatory • CV catheter, blood warmer ,rapid infusion device are desired if blood loss is anticipated
  23. 23. THORACIC ANESTHESIA 3) Monitoring:3) Monitoring: • Beside routine monitors (ECG,ETCO2,SPO2, NIBP) direct arterial monitoring is indicated in patients with poor cardiac or respiratory reserve and in resection of large tumors • CVP monitoring is highly advisable and it reflects the net effect of venous capacitance ,blood volume, and RT ventricular function • PAC is indicated in LT ventricle dysfunction
  24. 24. THORACIC ANESTHESIA 4) Induction of anesthesia:4) Induction of anesthesia: 1. After adequate preoxygenation, iv anesthesia is usually used for most patients 2. Direct Laryngoscopy is performed only after deep anesthesia to prevent reflex bronchospasm and obtund the cardiovascular pressor response 3. Endotracheal intubation is facilitated by succinylcholine or NDMR
  25. 25. THORACIC ANESTHESIA 4. Controlled PPV helps to prevent atelectasis, mediastinal shift, paradoxical respiration and facilitates surgery 5. Most thoracic procedures need DLT and its position is confirmed after introduction and after positioning using fiberoptic bronchoscopy
  26. 26. THORACIC ANESTHESIA 5) Maintenance of anesthesia:5) Maintenance of anesthesia: • All the current anesthetic techniques have been used successfully for thoracic surgery but the combination of a potent halogenated agent + opioid is usually preferred • N2O is not used • Muscle paralysis is maintained with NDMR • Iv fluids should be restricted to basic requirement and blood loss to avoid Lower Lung Syndrome especially in lung resection
  27. 27. THORACIC ANESTHESIA • ONE LUNG VENTILATION: The greatest risk of one lung ventilation is hypoxemia. To reduce this risk ; *the period of one lung ventilation kept to minimum *use 100% O2 Hypoxemia during one lung ventilation requires one or more of the following measures:
  28. 28. THORACIC ANESTHESIA Sure effective measures Probably effective measures 1. Periodic inflation of the collapsed lung 2. 5-10cm H2O CPAP to the collapsed lung 3. Early ligation of the ipsilateral pulmonary artery in pneumonectomy 1. 5-10cm H2O PEEP to the ventilated lung 2. Changing the TV and the RR 3. Continuous insufflation of O2 to the collapsed lung
  29. 29. THORACIC ANESTHESIA • If hypoxia persists : • To immediate reexpansion of the collapsed lung • The position of the tube is verified • The ETT is suctioned to exclude excessive secretions or obstruction • Pneumothorax on the dependant ventilated side should be excluded
  30. 30. THORACIC ANESTHESIA 6) Postoperative management:6) Postoperative management: • Most patients are extubated early to reduce the risk of pulmonary barotrauma, blowout of the bronchial stump and pulmonary infection • Double lumen tube is exchanged with regular tube • Patients are observed in PACU or ICU at least overnight
  31. 31. THORACIC ANESTHESIA • Pain management is of extreme importance as pain delays extubation, retains secretions and exaggerates hypoxia • Use either parentral (less preferred) or epidural narcotics • So routine postoperative care include: -semisetting position -supplemental O2 -close hemodynamic monitoring -aggressive pain management
  33. 33. THORACIC ANESTHESIA 1.1. Pulmonary cysts and bullae:Pulmonary cysts and bullae: • The greater risk of anesthesia is rupture during PPV tension pneumothorax • Induction of anesthesia with maintenance of spontaneous ventilation is desirable till the side of the bullae is opened • N2O is omitted because it can enlarge the air cavity • Pneumothorax is signaled by sudden onset of hypotension, bronchospasm, peak pressure
  34. 34. THORACIC ANESTHESIA 2. Lung abscess:2. Lung abscess: • Anesthetic management depends on early separation of both lungs to prevent soiling of the healthy lung • Rapid sequence iv induction with DLT with the patient in semi-up right position with the affected lung dependant • Frequent suctioning of the diseased to prevent soiling of the healthy lung
  35. 35. THORACIC ANESTHESIA 3. Bronchpleural fistula :3. Bronchpleural fistula : • Anesthetic management may be complicated by inability to ventilate the lungs because of large air leak • Rapid sequence iv induction with DLT or awake intubation with DLT to separate both lungs and ventilate the healthy lung only till the fistula is closed