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Anesthesia for Lung Volume Reduction Surgery

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1 Anesthesia for Lung Volume Reduction Surgery
Lung volume reduction includes lobectomy Pneumonectomy Segmental lung resection Indications: 1- patients with severe chronic obstructive pulmonary disease - pulmonary tumors 2 3 - necrotizing pulmonary infections and bronchiectasis

2 Preoperative Considerations
Tumors either benign or malignant, or can have an intermediate nature. Hamartomas account for 90% of benign pulmonary tumors; they are usually peripheral pulmonary lesions Bronchial adenomas are usually central pulmonary lesions typically benign but occasionally may be locally invasive and rarely can metastasize. These tumors include pulmonary carcinoids, cylindromas, and mucoepidermoid adenomas. Pulmonary carcinoids are derived from APUD cells and may secrete multiple hormones, including adrenocorticotropic hormone (ACTH) and argininevasopressin Malignant pulmonary tumors are divided into small ("oat") cell (20%) and non–small cell carcinomas (80%). The latter includes squamous cell (epidermoid) tumors, adenocarcinomas, and large cell (anaplastic) carcinomas Epidermoid and small cell carcinomas (central masses with bronchial lesion.) Adenocarcinoma and large cell carcinomas are more typically peripheral lesions that often involve the pleura.

3 Clinical Manifestations
cough, hemoptysis, dyspnea, wheezing, weight loss, fever, or productive sputum. . Pleuritic chest pain or pleural effusion suggests pleural extension. Involvement of mediastinal structures is suggested by hoarseness that results from compression of the recurrent laryngeal nerve, Horner's syndrome caused by involvement of the sympathetic chain, an elevated hemidiaphragm caused by compression of the phrenic nerve Dysphagia caused by compression of the esophagus, or the superior vena cava syndrome.

4 Pericardial effusion or cardiomegaly suggests cardiac involvement
Pericardial effusion or cardiomegaly suggests cardiac involvement. Extension of apical (superior sulcus) tumors can result in either shoulder or arm pain or both because of involvement of the C7–T2 roots of the brachial plexus (Pancoast syndrome). Distant metastases most commonly involve the brain, bone, liver, and adrenal glands. Lung carcinomas—small cell—(paraneoplastic syndromes). ectopic hormone production and immunologic cross-reactivity between the tumor and normal tissues. Cushing's syndrome, hyponatremia, and hypercalcemia may be encountered, resulting from secretion of ACTH, argininevasopressin, and parathyroid hormone, respectively Lambert–Eaton (myasthenic) syndrome is characterized by a proximal myopathy in which muscle strength increases with repeated effort Other paraneoplastic syndromes include hypertrophic osteoarthropathy, cerebellar degeneration, peripheral neuropathy, polymyositis, migratory thrombophlebitis, and nonbacterial carditis.

5 Bronchiectasis Bronchial muscle and elastic tissue is typically replaced by very vascular fibrous tissue. The latter predisposes to bouts of hemoptysis. Pulmonary resection is usually indicated for massive hemoptysis when conservative measures have failed and the disease is localized. Patients with diffuse disease have a significant chronic obstructive ventilatory defect

6 Infection Pulmonary infections may present as a solitary nodule or cavitary lesion (necrotizing pneumonitis). Lung resection is also indicated for cavitary lesions that are refractory to antibiotic treatment, are associated with refractory empyema, or result in massive hemoptysis

7 Anesthetic Considerations Preoperative Management
The majority of patients undergoing pulmonary resections have underlying lung disease The preoperative assessment: 1- clinicaly to exclude the presence of cor-pulmonal 2-Routine lab investigations 3- Preoperative chest radiographs and CT and magnetic resonance imaging (MRI) scans should be reviewed carefully. a-local extension of tumours b- Tracheal or bronchial deviation can complicate tracheal intubation or proper positioning of bronchial tubes c- airway compression can lead to difficulty in ventilating the patient following induction of anesthesia. d- Pulmonary consolidation, atelectasis, and large pleural effusions predispose to hypoxemia. e- The location of any bullous cysts or abscesses should be noted.

8 4- Echocardi–ography is very useful for assessing baseline cardiac function and may suggest evidence of cor pulmonale (right ventricular enlargement or hypertrophy). 5- Dobutamine stress echocardiography may be useful in detecting occult coronary artery disease. 6- Resectability & Operability: Resectability is determined by the anatomic stage of the tumor, whereas operability is dependent on the extent of the procedure and the physiological status of the patient. a- ipsilateral peribronchial or ipsilateral hilar lymph node metastases can be resected. b- Resection of lesions with ipsilateral mediastinal or subcarinal lymph node metastases, is controversial. C- scalene, supraclavicular, contralateral mediastinal, or contralateral hilar lymph node metastases are usually considered unresectable. D-In absence of mediastinal metastases, superior sulcus and chest wall tumors may be resected.

9 The extent of the surgery should maximize the chances for a cure but still allow for adequate residual pulmonary function postoperatively. Lobectomy via a posterior thoracotomy, through the fifth or sixth intercostal space, is the procedure of choice for most lesions. Segmental or wedge resections may be performed in patients with small peripheral lesions and poor pulmonary reserve. Pneumonectomy is necessary for curative treatment of lesions involving the left or right main bronchus or when the tumor extends to the hilum. A sleeve resection may be employed for patients with proximal lesions and limited pulmonary reserve as an alternative to pneumonectomy, the involved lobar bronchus together with part of the right or left main bronchus is resected, and the distal bronchus is reanastomosed to the proximal bronchus or the trachea.

10 Operative Criteria for Pneumonectomy
Operability is ultimately a clinical decision, but pulmonary function tests offer useful preliminary guidelines Preoperative Laboratory Criteria for Pneumonectomy(high risk): 1-Arterial blood gas PaCO2 > 45 mm Hg (on room air) PaO2 < 50 mm Hg   2-FEV1 < 2 L   FEV1/FVC < 50% of predicted   Maximum breathing capacity < 50% of predicted

11 5-split lung function tests
A- The most commonly used criterion for operability is a predicted postoperative forced expiratory volume at 1 second (FEV1) greater than 800 mL. The test is done by intravenous injection of radio active (133Xe or 99Tc)and meaurement of the pulmonary blood flow received by each lung separately using gama camera .Measurement of FEV1 is done. The percentage contribution of each lung to total FEV1 is assumed to be proportionate to the percentage of the total pulmonary blood flow it receives Removal of extensively diseased lung (nonventilated but perfused) may not adversely affect pulmonary function and may actually improve oxygenation.

12 B-Measurement of pulmonary artery pressure:
If the predicted postoperative FEV1 is less than 800 mL but resection is still considered, the ability of the remaining pulmonary vasculature to tolerate total blood flow can be tested . The main pulmonary artery on the diseased side is occluded with a balloon catheter; if the mean pulmonary artery pressure exceeds 40 mm Hg or the PaO2 decreases to < 45 mm Hg, the patient is not a candidate for pneumonectomy 6- Maximum oxygen consumption ( O2) during exercise . Patients with O2 > 20 mL/kg have low complication rates, whereas those with O2 < 10 mL/kg have unacceptably high morbidity and mortality.

13 Premedication Patients with moderate to severe respiratory compromise should receive little or no sedative premedication. Although anticholinergics (atropine, 0.5 mg intramuscularly or intravenously, or glycopyrrolate, 0.1–0.2 mg intramuscularly or intravenously) can theoretically inspissate secretions and increase dead space; clinically they are very useful in reducing copious secretions. This improves visualization during repeated laryngoscopies and facilitates the use of a fiberoptic bronchoscope.

14 Preparation 1- Optimal preparation may help prevent potentially catastrophic problems 2- Basic airway management preparation 3- multiple sizes of single- and double-lumen tubes 4- a flexible (pediatric) fiberoptic bronchoscope 5-a small-diameter "tube exchanger,“ 6- a continuous positive airway pressure (CPAP) delivery system 7- an anesthesia circuit adapter for administering bronchodilators should be immediately available. 8-Placement of epidural catheter is easier in awake rather than anaesthetised patient

15 Venous Access At least one large-bore (14- or 16-gauge) intravenous line is mandatory for all thoracic surgical procedures. Central venous access (preferably on the side of the thoracotomy) a blood warmer, and a rapid infusion device are also desirable if extensive blood loss is anticipated.

16 Monitoring Direct monitoring of arterial pressure is indicated for one-lung ventilation , for resections of large tumors (particularly those with mediastinal or chest wall extension), and for any procedure performed in patients who have limited pulmonary reserve or significant cardiovascular disease. Central venous access with monitoring of central venous pressure (CVP) is highly desirable for pneumonectomies and resections of large tumors. Pulmonary artery catheterization is indicated in patients with pulmonary hypertension, cor pulmonale, or left ventricular dysfunction; radiographic confirmation of the position of the catheter is useful in ascertaining that the pulmonary artery catheter (PAC) is not in a lung segment that is to be resected. When the tip of the PAC is in the nondependent (upper) lung and that lung is collapsed, cardiac output and mixed venous oxygen tension may be falsely depressed during one-lung ventilation. The balloon of a PAC should be inflated carefully following pneumonectomy because the remaining pulmonary vasculature has a significantly reduced cross-sectional area; balloon inflation can acutely increase right ventricular afterload and can lower left ventricular preload.

17 Induction of Anesthesia
After adequate preoxygenation, an intravenous anesthetic is used for induction of most patients( based on the patient's preoperative status.) Direct laryngoscopy should generally be performed only after deep anesthesia to prevent reflex bronchospasm and to obtund the cardiovascular pressor response. This may be accomplished by incremental doses of the induction agent, an opioid, or both Deepening anesthesia with a volatile inhalation agent may be preferable in patients with reactive airways. Tracheal intubation is facilitated with succinylcholine or a nondepolarizing agent; the former may be more appropriate if difficult laryngoscopy is anticipated. Most thoracotomies can be performed with an ordinary tracheal tube, but techniques for one-lung ventilation greatly facilitate most thoracic operations. Use of a single-lumen tracheal tube may be necessary, however, if the surgeon performs diagnostic bronchoscopy prior to surgery; once the bronchoscopy is completed, the single-lumen tube can be replaced with a double-lumen bronchial tube (above). Controlled positive-pressure ventilation helps prevent atelectasis, paradoxical breathing, and mediastinal shift; it also allows control of the operative field to facilitate the surgery.

18 Positioning Most lung resections are performed via posterior thoracotomy with the patient in the lateral decubitus position. Proper positioning is critical to avoid injuries and to facilitate surgical exposure. The lower arm is flexed and the upper arm is extended in front of the head, pulling the scapula away from the operative field Pillows are placed between the arms and legs, and an axillary roll is positioned just beneath the dependent axilla to avoid injury to the brachial plexus; care is taken to avoid pressure on the eyes and the dependent ear.

19

20 Maintenance of Anesthesia
combination of a potent halogenated agent (halothane, isoflurane, sevoflurane, or desflurane) and an opioid is preferred . Advantages of the halogenated agents include (1) potent dose-related bronchodilation (2) depression of airway reflexes (3) the ability to use a high inspired oxygen concentration (FIO2) (4) the ability to make relatively rapid adjustments in anesthetic depth (5) minimal effects on hypoxic pulmonary vasoconstriction Halogenated agents generally have minimal effects on HPV in doses < 1 minimum alveolar concentration (MAC)

21 Advantages of an opioid include
(1) generally minimal hemodynamic effects (2) depression of airway reflexes (3) residual postoperative analgesia. If epidural opioids are to be used postoperatively, their intravenous use should be limited during surgery to prevent excessive postoperative respiratory depression. Nitrous oxide (N2O) is generally not used because of the obligatory decrease in FIO2. Like volatile agents, nitrous oxide can also inhibit hypoxic pulmonary vasoconstriction and, in addition, can exacerbate pulmonary hypertension in some patients. Maintenance of neuromuscular blockade with a nondepolarizing neuromuscular blocking agent (NMBA) during surgery facilitates rib spreading as well as anesthetic management Sustained vagally mediated bradycardia due to surgical manipulations should be treated with intravenous atropine

22 Fluid management Intravenous fluids should generally be restricted in patients undergoing pulmonary resections. an intravenous fluid bolus is required to couteract the decrease in venous return when the chest is opened Colloid or blood is usually used Excessive fluid administration in the lateral decubitus position may promote a "lower lung syndrome," ie, gravity- dependent transudation of fluid into the dependent lung. The latter increases intrapulmonary shunting and promotes hypoxemia, particularly during one-lung ventilation. Moreover, the collapsed lung is also prone to edema following reexpansion as a result of surgical retraction.

23 Techniques for One-Lung Ventilation
Three techniques can be employed: (1) placement of a double-lumen bronchial tube, (2) use of a single-lumen tracheal tube in conjunction with a bronchial blocker (3) use of a single-lumen bronchial tube. Anatomic Considerations The adult trachea is 11–13 cm long. It begins at the level of the cricoid cartilage (C6) and bifurcates behind the sternomanubrial joint (T5). The wider right bronchus diverges away from the trachea at a 25° angle, whereas the left bronchus diverges at a 45° angle The right bronchus has upper, middle, and lower lobe branches, whereas the left bronchus divides into only upper and lower lobe branches; The orifice of the right upper lobe bronchus is about 1–2.5 cm from the carina, whereas that of the left upper lobe is about 5 cm distal to the carina.

24 Anatomy of the tracheobronchial tree

25 Right or left tube Right-sided tubes were designed for left thoracotomies, whereas left-sided tubes were designed for right thoracotomies Left sided are usually used: easy insertion less incidence of obstruction of the left upper lobe

26 Placement of double lumen tube

27 Protocol for placement of left sided tube

28 Management of One-Lung Ventilation
The greatest risk of one-lung ventilation is hypoxemia. To reduce this risk: The period of time of one-lung ventilation should be kept to a minimum 100% oxygen should be used. If peak airway pressures rise excessively (> 30 cm H2O), tidal volume may be reduced to 6–8 mL/kg and the ventilatory rate may be increased to maintain the same minute ventilation. Close monitoring of the pulse oximeter is mandatory. Periodic arterial blood gas analysis is helpful to ensure adequate ventilation. End-tidal CO2 measurement may not be reliable

29 Management of Hypoxemia during one-lung anesthesia
1) Periodic inflation of the collapsed lung with oxygen. (2) Early ligation or clamping of the ipsilateral pulmonary artery (during pneumonectomy). (3) CPAP (5–10 cm H2O) to the collapsed lung; this is most effective when there is partial reexpansion of the lung, which unfortunately can interfere with surgery. (4 )PEEP (5–10 cm H2O) to the ventilated lung. (5) Continuous insufflation of oxygen into the collapsed lung. (6) Changing the tidal volume and ventilatory rate.

30 Other measures 1- repeated suctioning
2- instillation of streptokinase into the tube may help facilitate the removal of clots 3- Pneumothorax on the dependent ventilated side should also be considered( may occur following extensive mediastinal dissection or with high peak inspiratory pressures.)

31 Factors known to inhibit HPV and thus worsen the right-to-left shunting include
1) very high or very low pulmonary artery pressures (2) hypocapnia (3) high or very low mixed venous PO2 (4) vasodilators such as nitroglycerin, nitroprusside, - adrenergic agonists (including dobutamine and salbutamol), and calcium channel blockers (5) pulmonary infection (6) inhalation anesthetics

32 Factors that decrease blood flow to the ventilated lung can be equally detrimental:
they counteract the effect of HPV by indirectly increasing blood flow to the collapsed lung. Such factors include : (1) high mean airway pressures in the ventilated lung due to high positive end-expiratory pressure (PEEP), hyperventilation, or high peak inspiratory pressures (2) a low FIO2, which produces hypoxic pulmonary vasoconstriction in the ventilated lung (3) vasoconstrictors that may have a greater effect on normoxic vessels than hypoxic ones (4) intrinsic PEEP that develops due to inadequate expiratory times.

33 Elimination of CO2 is usually not affected by one- lung ventilation provided minute ventilation is unchanged and preexisting CO2 retention was not present while ventilating both lungs; arterial CO2 tension is usually not appreciably altered.

34 Alternatives to One-Lung Ventilation
Ventilation can be stopped for short periods if 100% oxygen is insufflated at a rate greater than oxygen consumption (apneic oxygenation). Arterial PCO2 rises 6 mm Hg in the first minute, followed by a rise of 3–4 mm Hg during each subsequent minute. respiratory acidosis limits the use of this technique to 10–20 min . High-frequency positive-pressure ventilation and high- frequency jet ventilation have been used during thoracic procedures as alternatives to one-lung ventilation. A standard tracheal tube may be used with either technique. Small tidal volumes (< 2 mL/kg) allow decreased lung excursion, which may facilitate the surgery but still allow ventilation of both lungs.

35 Postoperative Management General Care
Most patients are extubated early to decrease the risk of pulmonary barotrauma and pulmonary infection. Patients with marginal pulmonary reserve should be left intubated until standard extubation criteria are met if a double-lumen tube was used for one-lung ventilation, it should be replaced with a regular single-lumen tube at the end of surgery. A tube exchanger should be used if the original laryngoscopy was difficult . Patients are observed carefully at least overnight in an intensive care unit (ICU) or intermediate care unit. Postoperative hypoxemia and respiratory acidosis are common and due to: atelectasis from surgical compression of the lungs and 1- shallow breathing ('splinting')" due to incisional pain. 2- Gravity-dependent transudation of fluid into the dependent lung. 3-Reexpansion edema of the collapsed nondependent lung particularly with rapid reinflation.

36 Postoperative hemorrhage complicates about 3% of thoracotomies and may be associated with up to 20% mortality. Signs of hemorrhage include increased chest tube drainage (> 200 mL/h), hypotension, tachycardia, and a falling hematocrit. Postoperative supraventricular tachyarrhythmias are common and should be treated aggressively . . Acute right ventricular failure is suggested by a low cardiac output, elevated CVP, oliguria, and a normal pulmonary capillary occlusion pressure. Routine postoperative care should include maintenance of a semiupright (> 30°) position, supplemental oxygen (40–50%), incentive spirometry, close electrocardiographic and hemodynamic monitoring, a postoperative radiograph, and aggressive pain relief.

37 Postoperative Analgesia
parenteral opioids best administered via a patient-controlled analgesia (PCA) device. A long-acting agent such as 0.5% ropivacaine (4–5 mL), injected two levels above and below the thoracotomy incision, typically provides excellent pain relief. These blocks may be done under direct vision intraoperatively or via the standard technique postoperatively. Intercostal or paravertebral nerve blocks improve postoperative arterial blood gases and pulmonary function tests and shorten hospital stay. Alternatively, a cryoanalgesia probe may be used intraoperatively to freeze the intercostal nerves (cryoneurolysis) and produce long- lasting anesthesia; unfortunately, maximum analgesia may not be achieved until 24–48 h after the cryoanalgesia procedure. Nerve regeneration is reported to occur approximately 1 month after the cryoneurolysis. Epidural opioids with or without a local anesthetic can also provide excellent analgesia .

38 Equally satisfactory analgesia may be obtained with either a lumbar or thoracic epidural catheter interpleural analgesia, also called intrapleural analgesia, can provide good analgesia following thoracotomy. Unfortunately, clinical experience has provided inconsistent results, possibly because of the necessary use of thoracostomy tubes and the presence of blood within the pleura


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