Surgery 5th year, 1st lecture (Dr. Ahmed Al-Azzawi)


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The lecture has been given on Sep. 30th, 2010 by Dr. Ahmed Al-Azzawi.

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Surgery 5th year, 1st lecture (Dr. Ahmed Al-Azzawi)

  1. 1. Thoracic Surgery Embryology,Surgical Anatomy,Pulmonary physiology Dr.Ahmed Al-Azzawi M.B.Ch.B,F.I.C.M.S Cardiothoracic&Vascular Surgeon University of Sulaimani College of Medicine
  2. 2. INTRODUCTION <ul><li>Thoracic surgery focuses primarily on the organs that support the delicate sequence of events that move air to blood and blood to tissues. </li></ul><ul><li>Air with adequate oxygen content must pass the upper airway, the trachea and the bronchi to reach the alveoli, properly warmed and humidified , for movement across alveolar membrane. </li></ul>
  3. 3. Respiratory system EMBRYOLOGY <ul><li>The respiratory system is an outgrowth of the ventral wall of the foregut ,and the epithelium of the larynx,trachea,bronchi,and alveoli originates in the endoderm. </li></ul><ul><li>The cartilaginous,muscular,and connective tissue components arise in the mesoderm . </li></ul><ul><li>In the 4 th week of development ,the tracheoesophageal septum seperates the trachea from the foregut ,dividing the foregut into the lung bud anteriorly and the esophagus posteriorly . </li></ul><ul><li>The lung bud developes into two main bronchi ,the right forms three secondary bronchi and three lobes ;the left forms two secondary bronchi and lobes . </li></ul>
  4. 4. <ul><li>After apseudoglandular (5_16 weeks) and canalicular (16_26weeks)phase ,cells of the cuboidal lined bronchioles change into thin ,flat cells type I aleveolar epithelial cells, in the seventh month,gas exchange between the blood and air in the primitive aleveoli is possible . </li></ul><ul><li>Before birth the lungs are filled with fluid with little protein,some mucous,and surfactant , which produced by type II aleveolar epithelial cells and which forms aphospholipid coat on the aleveolar memberanes . </li></ul><ul><li>At the beginning of the respiration the lung fluid is resorbed except for the surfactant coat,which prevent the collapse of the aleveoli during expiration by reducing the surface tension at the air _blood capillary interface . </li></ul><ul><li>. </li></ul>
  5. 5. <ul><li>Absent or insufficient surfactant in the premature baby causes RDS because of the collapse of the primitive aleveoli (hyaline memberane disease ). </li></ul><ul><li>Growth of the lungs after birth is due to an increase in the number of respiratory bronchioles and aleveoli and not to an increase in the size of the aleveoli ,new aleveoli are formed during the first 10 years of postnatal life </li></ul>
  6. 6. <ul><li>With growth the lung buds expand into the body cavity ,the spaces for the lungs are gradualy filled by the expanding lung buds . </li></ul><ul><li>The mesoderm which covers the outside of the lung ,developes into the visceral pleura . </li></ul><ul><li>The somatic mesoderm layers becomes the parietal pleura. </li></ul><ul><li>The space between the parietal and visceral pleura is the pleural cavity. </li></ul><ul><li>During further growth secondary bronchi divide repeatedly forming10 tertiary(segmental)bronchi in the right lung and 8 in the left creating the bronchopulmonary segments of the adults lung . </li></ul>
  7. 7. Maturation of the lungs <ul><li>Up to the seventh month ,the bronchioles divide continously into more and smaller canals,and the vascular supply increased steadly . </li></ul><ul><li>During the seventh month ,sufficient numbers of capillaries are present to guarantee adequate gas exchange and the premature infant is able to survive. </li></ul><ul><li>Fetal breathing movements begin before birth and cause aspiration of amniotic fluid .These movements are important for stimulating lung development and conditioning respiratory muscles. </li></ul><ul><li>Respiratory movements after birth bring air into the lungs,which expand and fill the pleural cavity </li></ul>
  8. 8. <ul><li>Growth of the lungs after birth is due primarly to an increase in the number of respiratory bronchioles and aleveoli. </li></ul><ul><li>It is estimated that only one –sixth of the adult number of aleveoli are present at birth. </li></ul>
  9. 13. Respiration <ul><li>Respiration includes the movement of air into and out of the lungs . </li></ul><ul><li>The exchange of gases between the air and the blood. </li></ul><ul><li>The transport of gases in the blood. </li></ul><ul><li>The exchange of gases between the blood and tissue. </li></ul>
  10. 14. Anatomy of the respiratory system <ul><li>The respiratory system consists of the nose,the nasal cavity,the pharynx,the larynx,the trachea,the bronchi,and the lungs. </li></ul><ul><li>The upper respiratory tract refers to the nose,nasal cavity,pharynx,and associated structures. </li></ul><ul><li>The lower respiratory tract includes the larynx,trachea,bronchi,and lungs. </li></ul>
  11. 16. <ul><li>The lung apices rise well above the level of the clavicles anteriorly and the scapula posteriorly. </li></ul><ul><li>The diaphragm rises as high as the level of the nipple. </li></ul><ul><li>The framework of the thoracic cage consists of the sternum, 12 thoracic vertebrae,10 pairs of the ribs that end anteriorly in segments of cartilage,and two pairs of floating ribs . </li></ul><ul><li>The thoracic inlet has arigid structural ring formed by the sternal manubrium,the short,semicircular first ribs,and the vertebral column. </li></ul>
  12. 18. TRACHEA <ul><li>The trachea is amemberanous tube that consists of connective tissue and smooth muscle,reinforced with 16 to 20 C-shaped pieces of cartillage. </li></ul><ul><li>The adult trachea is about 1.4 to 1.6cm in diameter and has an average length of 11 cm (range 10-13 cm). </li></ul><ul><li>It begins immediately inferior to cricoid cartillage. </li></ul><ul><li>It divides into the right and left primary bronchi at the level of T5. </li></ul><ul><li>The esophagus lies immediately posterior to the trachea. </li></ul>
  13. 19. BRONCHI <ul><li>The bronchi may be classified as primary ,secondary(lobar),and tertiary(segmental). </li></ul><ul><li>The right and left 1ry bronchus arise from the bifurcation of the trachea at T4/T5 intervertebral disc. </li></ul><ul><li>The right primary bronchus is shorter larger in diameter,and more vertically oriented than the left. </li></ul>
  14. 22. Secondary bronchus (lobar) <ul><li>There are three 2dry bronchi in the right lung upper,middle and lower. </li></ul><ul><li>There are two secondary bronchi in the left uppetr,and lower. </li></ul>
  15. 23. Tertiary bronchus <ul><li>There are 10 tertiary bronchi in the right lung : </li></ul><ul><li>The right superior lobar bronchus branches ;apical,posterior,and anterior. </li></ul><ul><li>Right middle;medial,lateral. </li></ul><ul><li>Right inferior:superior,anterior basal,posterior basal,medial basal,lateral basal. </li></ul>
  16. 24. <ul><li>In the left lung there are 8 tertiary bronchi: </li></ul><ul><li>Left superior lobar bronchus ;apicoposteror,anterior. </li></ul><ul><li>Lingular bronchus;superior lingular,inferior lingular. </li></ul><ul><li>Inferior lobar bronchus;superior,anteromedial basal,posterior basal,lateral basal. </li></ul><ul><li>Carina: </li></ul><ul><li>Keel-shaped cartillage lying within the tracheal bifurcation. </li></ul><ul><li>Carina trachealis is an important landmark during endoscopy of the broncheal tree. </li></ul>
  17. 25. Lungs
  18. 26. <ul><li>Oblique fissure: </li></ul><ul><li>Deep groove in the surface of the lung that separates the upper lobe from the lower lobe (both lungs)and the middle lobe from the lower lobe (right lung). </li></ul><ul><li>Oblique fissure extends from the level of T3 vertebrae posteriorly to the 6 th costochondral junction anteriorly. </li></ul><ul><li>Horizental fissure: </li></ul><ul><li>Deep groove in the surface of the lung that separates the middle lobe from the upper lobe (right lung only). </li></ul><ul><li>It extends from the 5 th rib at the mid-axillary line along the 4 th rib to the sternum anteriorly. </li></ul>
  19. 27. Pleural cavities <ul><li>The lungs are contained within the thoracic cavity. </li></ul><ul><li>Each lung is surrounded by aseparate pleural cavity. </li></ul><ul><li>Each pleural cavity is lined with aserous memberane called the pleura. </li></ul>
  20. 28. PLEURA <ul><li>Serous membrane lining the pleural cavity. </li></ul><ul><li>There are two types of pleura:visceral pleura covers the lungs ,parietal pleura lines the inner surfaces of the walls of pleural cavity,parietal pleura is sensitive to pain but visceral pleura is not sensitive to pain. </li></ul><ul><li>Cervical parietal pleura (sibson,s fascia or suprapleural membrane)also called cupula or cervical dome of pleura it extends above the level of the 1 st rib into the root of the neck. </li></ul>
  21. 29. <ul><li>2.Costal parietal pleura:on the inner surfaces of the ribs,costal cartilages,and intercostal mm. </li></ul><ul><li>3.Mediastinal parietal pleura:on the lateral surface of the mediastinum. </li></ul><ul><li>4.Pulmonary ligament:fold of pleura located below the root of the lung where the visceral and the medistinal parietal pleura are continuous with each other. </li></ul>
  22. 30. Blood supply <ul><li>Pulmonary trunk from the right ventricle gives right and left pulmonary arteries which supply the lungs with deoxygenated blood . </li></ul><ul><li>Pulmonary artery: </li></ul><ul><li>Right: gives superior lobar artery to the superior lobe and inferior lobar the middle and inferior lobe, </li></ul><ul><li>Left:sup.lobar the sup. Lobe and inferior lobar a. to inferior lobe. </li></ul>
  23. 31. <ul><li>Pulmonary vein drains into left atrium usualy two pulmonary veins :superior and inferior. </li></ul><ul><li>Bronchial arteries: </li></ul><ul><li>Left bronchial artery arise from descending thoracic aorta there are usualy two left bronchial arteries. </li></ul><ul><li>Right bronchial a.from the 3 rd right posterior intercostal or may arise from the left bronchial artery. </li></ul>
  24. 32. Ventilation and lung volumes <ul><li>Changing thoracic volumes </li></ul><ul><li>Inspiration occurs when the diaphragm contracts and the external intercostal mm lift the rib cage,thus increasing the volume of the thoracic cavity . </li></ul><ul><li>Expiration can be passive or active .Passive expiration during quiet breathing occures when the mm of inspiration relax </li></ul>
  25. 33. Pressure changes and airflow <ul><li>Respiratory mm cause changes in thoracic volume,which cause changes in aleveolar volume and pressure. </li></ul><ul><li>During inspiration ,air flows into the aleveoli bec.atmospheric presure is greater than aleveolar pressure. </li></ul><ul><li>During expiration,airflows out of the aleveoli bec.aleveolar pressure is greater than atmospheric pressure. </li></ul>
  26. 34. Lung Recoil <ul><li>The lungs tend to collapse bec. Of the elastic recoil of the connective tissue and surface tension of the fluid lining the aleveoli. </li></ul><ul><li>The lungs normally do not collapse bec. Surfactant reduces the surface tension of the fluid lining the aleveoli and pleural pressure is less than aleveolar pressur. </li></ul>
  27. 35. Changing Aleveolar Volume <ul><li>Increasing thoracic volume results in decreased pleural pressure,increased aleveolar volume,decreased aleveolar pressure,and air movement into the lungs. </li></ul><ul><li>Decreasing thoracic volume results in increased pleural pressure,decreased aleveolar volume,increased aleveolar pressure,and air movement out of the lungs. </li></ul>
  28. 36. Pulmonary Volume and Capacities <ul><li>There are four pulmonary volumes:tidal v.,inspiratory reserve,expiratory reserve,and residual volume. </li></ul><ul><li>Pulmonary capacities are the sum of two or more pulmonary volumes and include vital capacity and total lung capacity. </li></ul><ul><li>The forced expiratory vital capacity measures the rate at which air can be expelled from the lungs. </li></ul>
  29. 37. Pulmonary physiology . Preoperative evaluation and perioperative care of a patient includes A . Tissue diagnosis of primary disease and decision if an operative procedure is indicated B . Assessment of patient’s general condition C . Preoperative preparation and postoperative care The Evaluation of pulmonary function includes assessment of cardiac function, the oxygen carrying red cells, the lungs, chest wall and ventilatory muscular function
  30. 38. <ul><li>The surgeon must make acareful assesment of the patient,s ability to withstand the contemplated procedure. </li></ul><ul><li>Major predictors of the postoperative procedure include the extent of resection,pre-existing cardiopulmonary disease,age,and other co-morbid condition. </li></ul><ul><li>Complete pulmonary function tests including lung volumes,spirometry,diffusion capacity,and arterial blood gases. </li></ul>
  31. 39. Pulmonary mechanics <ul><li>Vital capacity(VC),the amount of air that can be forcefully expelled from amaximally inflated lung position. </li></ul><ul><li>The forced expiratory volume in 1s(FEV1)is adynamic measurement of apatient ability to move volumes of air during units of time. </li></ul><ul><li>The FEV1 usually is reported as apercentage of VC(FEV1/VC)as well as actual volume,the FEV1 is reduced in obstructive airway disease. </li></ul>
  32. 40. Blood-Gas Determination <ul><li>Measurement of the arterial blood gases and pH is routine in the preoperative evaluation. </li></ul><ul><li>Ameasurement of arterial CO2 pressure(PaCO2)provides an immediate indication of the patient aleveolar ventilation,any value >46 torr means that there is hypoventilation . </li></ul><ul><li>PaO2 arterial O2 pressure is also important,normaly it greater than 85 torr. </li></ul>
  33. 41. <ul><li>Lung physiology </li></ul><ul><li>A . Well suited for efficient exchange of O2 and CO2 with a large surface area and low perfusion pressure ( 300 million alveoli) </li></ul><ul><li>B . Gas exchange controlled by two pumps - the right ventricle and the chest cage - diaphragm </li></ul><ul><li>C . Elastic recoil of lungs ejects gas and fibrous skeleton maintains airway patency </li></ul><ul><li>D . Clinical evaluation of pulmonary function </li></ul><ul><li>1 history and physical - exercise tolerance </li></ul><ul><li>2 CXR, ABG </li></ul><ul><li>3 simple spirometry </li></ul><ul><li>4 vital capacity ( FVC )- total exhaled volume </li></ul><ul><li>E . FEV1 - forced expiratory volume at one second - indication of flow </li></ul><ul><li>1. FEV1 1000-2000 ml adequate for surgery </li></ul><ul><li>2.FEV1 800 ml or less preclude surgical resection </li></ul><ul><li>D . Restrictive disease - vital capacity, inspiratory and expiratory reserves are diminished - can result from diseases of the lung, pleura, chest cage and muscles - kyphoscoliosis, ARDS, pleural effusions or fibrosis Funcitonal residual volume is decreased limited capacity to expand lungs but no difficulty emptying lungs </li></ul><ul><li>E . Obstructive Disease - lung elastic recoil decreases, compromising the force </li></ul><ul><li>of exhalation - most common form in clinical practice usually due to smoking, damaged alveoli can lead to pulmonary HTN unsupported airways leads to airway trapping and atelectasis </li></ul>
  34. 42. <ul><li>Ventilatory Pump and Work of Breathing </li></ul><ul><li>A . Ventilatory pump consist of the thoracic cage and ventilatory muscles </li></ul><ul><li>B . The ventilatory pump is a suction pump which expands the chest cage to pull air into the lungs </li></ul><ul><li>C . Dyspnea signals that the work required of the ventilatory muscles has reached </li></ul><ul><li>a level that exceeds the comfortable capacity of the patient </li></ul><ul><li>D . Thoracotomy creates a region of non - contractile muscles which lowers tidal </li></ul><ul><li>volume and increases respiratory rate </li></ul><ul><li>E . Several disease processes can cause ventilatory pump failure </li></ul><ul><li>1 central depression </li></ul><ul><li>2 muscle paralysis </li></ul><ul><li>3 fatigue </li></ul><ul><li>4 mechanical defects in the thoracic cage - trauma, post - surgical a ) failure of ventilatory pump leads to atelectasis and decreased lung compliance </li></ul><ul><li>b ) functional residual volume decreases with loss of functional alveoli </li></ul><ul><li>c ) post - operative pain control - epidural can help prevent splinting and therefore atelectasis </li></ul>
  35. 43. <ul><li>Work capacity of ventilatory muscles are trainable - sedentary patients will poor muscle function as compared to active patients </li></ul><ul><li>A . Fluid Exchange and Lung Water blood circulating through normal lung capillaries at normal rates and pressure causes a net fluid movement from the capillaries into the lung interstitium . The filtered fluid is picked up by the lymphatics and returned to the circulation Management of fluid therapy is critical in post - operative pulmonary resection patients since this fluid balance is disrupted </li></ul><ul><li>increased filtration post - operatively </li></ul><ul><li>decreased capillary bed and lymphatic mass </li></ul><ul><li>increased cardiac output </li></ul><ul><li>must carefully titrate fluid balance especially in pneumonectomy patients </li></ul>
  36. 44. <ul><li>Ventilation - Perfusion Incoordination effective gas transfer relies on the coordination of ventilation and perfusion </li></ul><ul><li>A . Ventilation - perfusion mismatch occurs post - operatively </li></ul><ul><li>B . V / Q mismatch is the most common form of post - operative hypoxemia </li></ul><ul><li>C . Usually secondary to the development of atelectasis </li></ul>
  37. 45. <ul><li>Shunt Fraction </li></ul><ul><li>Determines the fraction of blood ejected by the left ventricle that has no gas exchange in the lungs </li></ul><ul><li>Patients with a shunt fraction > 0.15 to 0.20 are vulnerable to a low C . O . </li></ul><ul><li>Tissue oxygen delivery falls </li></ul><ul><li>Pulmonary artery catheter should be placed to optimize C . O . </li></ul>
  38. 46. <ul><li>One Lung Anesthesia </li></ul><ul><li>A . Procedure of choice for pulmonary resection </li></ul><ul><li>B . Videothoracoscopy has increased demand </li></ul><ul><li>C . Unventilated lung is perfused and is a source of an intrapulmonary shunt that can lead to hypoxemia </li></ul><ul><li>D . Usually ventilated on 100 % oxygen </li></ul>
  39. 47. <ul><li>Pneumonectomy lung reduction surgery </li></ul><ul><li>A . Derived from the observation of chest wall adaptation in lung transplant patients </li></ul><ul><li>B . Bilateral stapling of peripheral lung tissue to diminish lung volumes </li></ul><ul><li>C . Reinforced with bovine pericardial strips to prevent leaks </li></ul><ul><li>D . Improvement in symptoms and FEV1 </li></ul><ul><li>E . Improves diaphragmatic motion </li></ul>
  40. 48. <ul><li>Summary of Evaluation of Gas Exchange Function - background facts for assessing pulmonary function are as follows : </li></ul><ul><li>A . There is a large reserve in normal individuals </li></ul><ul><li>B . Condition of the ventilatory muscles depends on the physical state of the patient </li></ul><ul><li>C . As lung volume falls, airways in dependent areas of the lung close </li></ul><ul><li>D . With aging and smoking, airways close at higher lung volumes </li></ul><ul><li>E . V / Q mismatch occurs with airway closure </li></ul><ul><li>F . V / Q mismatch requires increased alveolar ventilation to maintain the same amount of gas exchange </li></ul><ul><li>G . Spirometry measures the volumes o flung and the ability to move air </li></ul><ul><li>H . PaCO2 is an indicator of adequacy of ventilation </li></ul><ul><li>I . PaO2 is an indicator of adequacy of oxygenation </li></ul>
  41. 49. <ul><li>THANKS FOR ALL </li></ul>