R MILROY & K KERR RICHARD HUBBORD 314 asthma for many years before the endobronchial tumor is identi \201 ed and treated. Benign papillomatous tumors of the airways include juvenile papillomatosis, solitary squamous cel l papilloma, mixed squamous and glandular or pure glandular papillomas and papillary adenom a. All these epithelial neo- plasms must be distinguished microscopically from rare soft ti ssue endobronchial neoplasms and non-neoplastic condi- tions such as in \202 ammatory poly ps, amyloid tumors, inhaled, impacted foreign bodies and endometriosis. endobronchial tumors and the pathology is as in lesions found in more common sites (see ear lier sections). Granular cell tumor Bronchopulmonary granular cell tumors are rare and usually develop in m iddle age. They may be found inciden- tally or may present with endobronchial symptoms. The y may be visible on bronchoscopy and biopsy is often diagnostic. Despite their histologic a ppearance of in \201 ltrating benign- looking cells with granular cytoplasm, they are of p eriph- eral nerve sheath (Schwann cell) origin and express S100 protein, which is diagnosti cally useful. Although these tumors grow only slowly and are almost always benign, resectio n is the recommended treatment. Papillomas These are usually squamous but glandular papillomas and mixed squamous and gland ular papillomas have also been described. Human papilloma virus has been identi \201 ed as an aetiologi- cal factor in the development of squamous papillomas. Solitary squamous lesi ons are seen mostly in males (mean age 53). Around a \201 fth of squamous lesions may sho w atypia and malignant change, though rare, is reported, em- phasising the need for complet e excision when possible. Glandular and mixed lesions are extremely unusual, occur equally in both sexes, with a mean age of 65. Multiple squamous lesions in the form of juvenile pap illo- matosis of the upper trachea and larynx can rarely affect the lower trachea or large bronchi. These usually occur in young patients and again have been associated with the huma n papilloma virus. Non-neoplastic endobronchial lesions Bronchial in \202 ammatory polyps These are polyps co nsisting of granulation tissue covered by respiratory or a metaplastic squamous epithelium and are related to airway in \202 ammation or trauma. They have been described in conjunct ion with chronic bronchi- tis, bronchiectasis and cystic \201 brosis and even as a compli - cation of bronchial biopsy. They are generally solitary but multiple polyps have been enc ountered. They are entirely benign, have no malignant potential and resolve either spontane ously or with antibiotic treatment. Bacillary angiomatosis This reactive vascular proliferation usually occurs in the skin and lymph nodes in patients infected with HIV. How- ever it has been described in the respirato ry tract where it results in an endobronchial polyp. Chest wall involvement with intra thor acic spread has also been reported. On microscopy capillaries lined by endothelial cells ar e admixed with neutrophils, cell debris and often clumps of bacilli. The microscopic appear ances differ from Kaposi \200\231s sarcoma by the absence of spindle cells and the presence of in \202 ammation. The treatment for this condition is with macrolide antibiotics. Bronchial gland tumors These arise from the sero-mucous glands of the airways. Some, such a s muco-epidermoid or adenoid cystic tumors are malignant and beyond the scope of this chap- ter. Benign bronchial gland tumors usually arise in large airways, protrude endobronchiall y and thus the character- istic \200\230bronchial \200\231 symptoms of cough and haemoptys is are often seen. Presentation may also be with recurrent epi- sodes of pneumonia due to o bstruction by the tumor. These tumors occur with an equal incidence in males and females. A ll are rare and can occur at any age. Histopathologically these lesions are mucous cell, on co- cytic and pleomorphic adenomas. As they do not in \201 ltrate, the overlying bronchial mucosa is usually intact at bronchoscopy. Conclusion A large range of benign lung tumors have been described in the literature althou gh they are relatively rare, some extremely so. They often are asymptomatic and detected on routine CXR but may present with endobronchial symptoms if they involve the airway. Benign lung tumors do grow, albeit slowly, and will cause pressure symptoms if not treated. De \201 nitive diagnosis will almost always require biopsy, though the true nature of the lesi on, including its benign nature, often requires full examination of the completely resected lesion. The treatment of choice is surgical resection if the patient is \201 t enough. Acknowledgements The authors very gratefully acknowledge the help of Jean Elliot (Postgradu ate Center Manager at Stobhill Hospital, Glasgow) with producing the manuscript and Dr Mike Sproule, Consultant Radiologist, Gartnavel General Hospital, Glasgow for supplying some of the images. Fig. 13.9.5 This is a resected pleomorphic adenoma from the main carina. Tracheobronchial w all is present at the base of the lesion, which itself comprises a smooth, rounded mass, wh ich protruded into the trachea and presented as acute onset asthma. (See Plate 12.) Further reading Travis, WD, Brambilla E, Muller-Hermelink HK, et al. (eds.) World Health Or ganization Classification of Tumors: Pathology and Genetics of Tumors of the Lung, Pleura, Thymus, and Heart 2004 Lyon: IARC Press. Endobronchial non-epithelial tumors Endobronchial cases of hamartoma and lipoma are well de scribed. Their presentation is typical of obstructive This page intentionally left blank P SHAH RICHARD HUBBORD 316 13.10 Transbronchial \201 ne needle aspiration Introduction Transbronchial \201 ne needle aspiration (TBNA) is a simple bronchoscopic te chnique which allows sampling of medi- astinal lymph nodes, masses adjacent to the airways and sub-mucosal disease. Its main role is in the diagnosis and staging of suspected lung ca ncer but it also has a role in non-malignant disease such as sarcoidosis. The procedure is extremely safe and the incidence of pneumothorax, pneumo-mediastinum and hemorrhage is low and ranges from 0.05% \200\2230.2%. Planning and site selection is an important part of TBNA and has an important in \202 uenc e on the yield. With the new multi-slice CT scan reformatting software with virtual broncho scopy mode and lymph node highlighting will allow the beginner to correctly choose the site of needle aspiration. Position Vertical position Anatomical lymph node site Anterior approach Posterior approach Equipment A variety of needles are available and the key features should include: 1 The nee dles should be retractable into a protective Right paratracheal 7 \200\2238 o \200\231clock 1 \200\2232 2 \200\2234 interspaces above carina o \200\231clock Left paratracheal 3 o \200\231clock 9 o \200\231clock Level of carina or one interspace above sheath 2 Insertion length of the needle should be between 1 space below carina in right main bronchus 9 o \200\231clock in right main bronchus Subcarinal 3 o \200\231clock in right main bronchus 13 \200\22315mm 3 The needle gauge should be between 18 \200\22322 gauge. Both single-use disposable and partly reusable sheaths are available. The larger gauge need les have a greater chance of yielding some tissue for histological analysis. The choice of needle comes down to individual preference but speci \201 c needles may be more suitable f or certain circumstances. The Olympus NA-2C-1 needle may be more suitable for an inexperien ced user as it consists of a helical metallic outer protective sheath and an inner disposab le needle. Hence it is less likely to result in damage to the broncho- scope and the stiffn ess allows greater precision. An 18 gauge Wang needle may be more appropriate when a pa- ti ent has suspected sarcoidosis and a histological sample is desirable. Posterior Carinal 12 \200\22312.30 o \200\231clock 5.30 \200\2236.0 o \200\231clock Level of carina Anterior Carinal 6 \200\2236.30 o \200\231clock 12 \200\22312.30 o \200\231clock Level of carina Right Main bronchial 6 o \200\231clock 12 o \200\231clock 1 space below carina in right main bronchus Left main bronchial 6 o \200\231clock 12 o \200\231clock 1 space below carina in left main bronchus Right Hilar 9 o \200\231clock 3 o \200\231clock Anterior spur of right upper lobe/ proximal portion of bronchus intermedius just below orig in of right upper lobe Site selection A recent CT scan of the thorax should always be reviewed prior to the proced ure and the site of the trans-bronchial \201 ne needle aspiration planned. A simple appro ach is to consider the airway as a clock face and to relate the posi- tion of the lymph nod es or mass accordingly. Remember that the CT scan acquires images from the patient \200\231 s feet upwards, whereas during bronchoscopy we examine the airways from the head downwards. Hence on the CT scan the left side is in the direction of 3 o \200\231clock whereas in the patient at bronchoscopy the left side is towards the 9 o \200\231clock position. This can be corrected by \202 ipping the images of the CT in the vertical axis. Furthermore, if th e patient is being approached from the front at bronchoscopy the anterior aspect is at 6 o \200\231clock whereas the posterior aspect is at 12 o \200\231clock. In contrast on the CT scan the anterior aspect is at 12 o \200\231clock and the posterior aspect at 6 o \200\231c lock. Further allowance needs to be made by \202 ipping the image in the horizontal axis. Note this last transposition is not required if the patient is being approached at broncho scopy from the back of the patient who is lying supine. The vertical position also needs to be estimated and this can be done by calculating the cartilage rings above or below the ca rina. For hilar nodes it may be more appropri- ate to use the origin or relative location o f the segmental or lobar bronchi to give the site of aspiration. Left Hilar 3 o \200\231clock 9 o \200\231clock Origin of left lower lobe bronchus Fig. 13.10.1 Transbronchial \201 ne needle aspiration (TBNA). Where anterior approach denotes a bronchoscopy per- formed on a patient in a semi-recumbent procedure being approached from in front of the patient and posterior approach is where th e patient is lying supine and approached from behind. The positions are described as a cloc kface and the vertical position in terms of cartilage ring spaces. Technique The objective is to insert the needle through the airway wall into the underlying lymph node or mass and obtain samples for cytology. The most widely used technique is to a ppose the hub of the needle onto the airway wall and then advance the needle out. The angle between the air- way wall and the needle should be at least 45 degrees and the distal end of the bronchoscope angulated so as to advance the needle as perpendicularly as possible. O nce the needle has been inserted fully through the airway an assistant applies suction with a syringe on the distal CHAPTER 13.10 Transbronchial \201 ne needle aspiration 317 Guided TBNA EBUS TBNA Integrated linear array ultrasound bronchoscopes are now available wh ich allow accurate image guided trans- bronchial needle aspiration. This technique signi \201 cantly in- creases the sensitivity of the procedure (over 90%) and allows sampling of lymph nodes as small as 5mm in size. end and the operator gently manipulates the needle back and forth in the lymph node. This i s known as the jabbing method. With the piggy back method the needle is prot- ruding out, a nd the bronchoscope and TBNA needle is advanced as a single combined unit through the airwa y wall. In contrast with the cough technique the protruding needle is apposed to the airway wall and the patient is asked to cough gently. The force of the constricting airways pushe s the needle through the airway wall into the target area. Superdimension TBNA This system creates a virtual GPS map of the lung and mediastinum. A vi rtual bronchoscopy is performed from data obtained from a multi-slice CT and speci \201 c landmarks identi \201 ed. The mediastinal lymph nodes can be marked as speci \201 c targe ts. At bronchoscopy a magnetic locating guide is used to identify the same anatomical point s marked on the CT scan and the two pieces of information integrated together. This then al lows the operator to navigate the locatable guide to target areas. The catheter is held in position, the locatable guide removed and replaced by a TBNA needle. This technique also si gni \201 cantly improves the sensitivity of TBNA although it is not performed under real t ime imaging. Tissue preparation The samples obtained can be either spread onto slides and then \201 xe d or injected into saline or Cytolite solution for processing. Any tissue specimens that ar e obtained should be placed in formalin and sent for histopathology. The presence of a cyto -pathologist with rapid staining tech- niques and appropriate equipment signi \201 cantly improves the ef \201 cacy of TBNA. Once the cytologist is con \201 dent that malignant ce lls are present from a specimen obtained from the highest staged lymph nodes, no further sa mpling is required. This considerably reduces the time and cost of the procedure. In the ab sence of rapid on site cytology (ROSE), the author recommends 4 needle passes at each abnor mal lymph node site starting from the highest stage lymph node \201 rst. AUTHOR \200\231S TIPS \200 Perform TBNA prior to any other aspect of the proce- dure to eliminate the risk of false po sitive. Sample lymph nodes from the highest staging site \201 rst e.g. Contra-lateral lym ph nodes prior to ipsi-lateral lymph nodes or N2 lymph nodes prior to bronchial hilar lymph nodes. Treat all negative results as false negative and consider additional sampling techn iques such as endobronchial ultrasound guided TBNA or mediastinoscopy. Role in speci \201 c diseases Diagnosis and staging of lung cancer TBNA has a fundamental role in the diagnosis and staging of lung cancer. In a prospective series of patients with sus- pected lung cancer, 30% of patients underwent bronchos- copy with TBNA. It was the sol e mode of diagnosis in 23% of patients. It provided staging information in 49 % of patients and only 1 in 1.47 procedures were needed to be performed to correctly diagnose or stage o ne patient. The sensitivity in the literature ranges from 39-78% depending on the prevalenc e of disease in the study group and meth- odological variations, but it is a simple procedu re that can be performed at the time of initial bronchoscopy. The advantages of TBNA are th at it can be established in any bronchoscopy unit with minimal cost. Consequently it can be performed in any individual who is \201 t for bronchoscopy and can be incorporated into the diagnostic pathway with- out incurring any delays in the assessment of patients. It als o minimizes the number of investigations that patients require for both diagnosis and stagi ng. Further reading Harrow EM, Abi-Saleh W, Blum J, et al. The utility of transbronchial needle aspiration in the staging of bronchogenic carcinoma. Am J Respir Crit Care Med 2000; 161(2 Pt 1): 601 \200\223607. Holty JE, Kushner WG, Gould MK. Accuracy of transbronchial needle aspiration of medaistinal staging of non-small cell lung cancer: a met-analysis. Thorax 2005; 60: 949 \200\223955. Patelli M, Lazzari L, Poletti V, et al. Role of \201 beroptic transbronchial needle aspir ation in the staging of N2 disease due to non-small cell lung cancer. Ann Thorac Surg 2002; 73: 407 \200\223411. Shah PL, Singh S, Bower M, et al. The role of transbronchial \201 ne needle aspiration (T BNA) in an integrated care pathway for the assessment of patients with suspected lung cance r. J Thoracic Oncol 2006; 1; 324 \200\223327. Role in granulomatous diseases The yield for TBNA in granulomatous disease is lower than th at for malignant disease as predominantly cytological samples are obtained. The diagnosis o f sarcoid is based on the presence of granulomas and hence more con \201 dently made when tissue specimens are obtained. Wang KP, Terry PB. Transbronchial needle aspiration in the diagno- sis and staging of bronc hogenic carcinoma. Am Rev Respir Dis 1983; 127:344 \200\223347. P BARBER 318 13.11 Interventional bronchoscopy techniques Introduction That portion of a lung tumor which lies within or com- presses the bronchial l umen is often the cause of many of its symptoms; examples include cough, haemoptysis, and b reathlessness or infection caused by obstructive collapse. There may also be life-threateni ng large-airway obstruc- tion. The ability to access the large and medium-sized airways wit h a \202 exible or rigid bronchoscope enables not only diagnostic and staging procedures to be carried out but also the administration of a number of therapies. The following may b e achieved: \200 \200 \200 Diathermy (electrocautery) A high-frequency alternating current is used to generate heat, e nabling coagulation, cutting or vapourisation of tissue, dependent on the temperature gener ated \200 Uses an insulated probe or snare, in direct or close contact. Can be delivered via a \202 exible bronchoscope, suitably insulated or grounded. Used for palliative debulking, the re moval of peduncu- lated lesions, and the eradication of early-stage disease. Complications are comparable with thermal laser and include bleeding, airway obstruction, and airway perf oration. FiO2 should be kept below 40% to reduce the danger of endobronchial \201 re. Ele ctrocautery should not be applied to the full circum- ference of an airway, in order to min imize the risk of bronchial stricture. Symptom relief. Ablation of large-airway obstructing tumors. Stabilization of life-threaten ing tracheal obstruction prior to de \201 nitive tumor-reducing therapy. The eradication o f small intra-bronchial tumors. The treatment of benign lesions. \200 Endobronchial treatment techniques fall into three categories. 1 Physical methods of tumor destruction and removal: Argon plasma coagulation (APC) This is a non-contact technique using a probe to deliver ion ized argon gas to produce coagulative necrosis. \200 (a) Endobronchial resection and dilatation. (b) Thermal laser, diathermy, and argon plasma coagulation. (c) Cryotherapy. More super \201 cial than diathermy, causing coagulation to a depth of 2 \200\2233mm. Effe ctive for haemostasis but not for the debulking of large tumors. Minimal risk of airway per foration. Can be used with uncovered metal stents. Normally requires a power of 40 watts an d a gas \202 ow of 2 litres per minute. 2 Biological therapies, with tumor selectivity and a delayed but potentially prolonged effect: (a) Brachytherapy. (b) Photo-dynamic therapy. \200 \200 3 Stenting. Endobronchial resection Rigid bronchoscopy is normally required for the safe and effective removal or debridement of an endobronchial tumor using suction, forceps, or the bronchoscop e tip itself to increase airway caliber. It may be combined with electro-coagulation and ot her thermal or freezing techniques. It is principally a palliative procedure but can occasi onally be curative for benign and low-grade tumors. Endoscopic resection can be life-saving in critical upper-airway obstruction and is also useful to stabilize an airway to allow ot her treatment (such as brachytherapy) which would otherwise be hazardous. It is often requi red as a debulking procedure to remove dead tumor after photodynamic therapy. Diathermy and APC may be delivered using combined equipment, increasing \202 exibility of treatment. Cryotherapy \200 \200 Uses freezing to destroy tumor. A cryoprobe delivers liquid nitrogen or nitrous oxide, cool ing the probe tip to -80 C on expansion (the Joule \200\223 Thomson effect). Used to treat haemoptysis and to remove obstructing tumor. Some of the treatment effect is delayed, and several treatments may be required. Can be used with the flexible bronchoscope \200\223don \200\231t freeze the videochip! Thermal destruction/coagulation There are a number of variants: NdYAG laser \200 Brachytherapy The word derives from the Greek \200\230Brachis \200\231, meaning \200\230c lose to \200\231. The technique uses a standard \202 exible bronchoscopy technique to pla ce a blind-ending catheter or applicator through or alongside an endobronchial obstructing tumor; a radioactive source is then delivered from a safe, attached to its drive-cable. The treatment delivers an intense dose of radiation to a limited volume of tissue, eliminating or minimizing radiation damage to surrounding organs. A high dose-rate iridium source is n ormally used, enabling treatment to be delivered in minutes. Most centers use fractionated regimes. \200 \200 \200 Normally used with a rigid bronchoscope to allow good airway control and the management of complications, especially hemorrhage. Small tumors and granulations can be removed using a \202 exible bronchoscope to deliver laser light. Light is transmitted by a coated \202 exible quartz- \201 bre, using a non-contact technique. FiO2 must be less than 30% to prev ent \201 re risk. Coagulation occurs at lower powers (30 \200\22335watts), vapourization at higher power (40 + watts). Complications include bleeding, hypoxia, and bronchial perfor ation. \200 Effective for primary and secondary palliation Results comparable with external beam radiot herapy Potentially curative for small intraluminal tumors CHAPTER 13.11 Interventional bronchoscopy techniques 319 Offers additional \202 exibility as an alternative treatment in a number of situations. C omplications include radiation bronchitis, fibrotic stenosis, and massive fatal haemoptysis variably reported at 3 \200\22330%, probably local dose-dependent. They are most often placed using a rigid bronchoscope but some can be placed with a \202 exible bronchoscope, with or without radiological screening. Most bronchial stents are made either of silicone or metal mesh, especially Nitinol, a Nickel-Titanium alloy which retain s its manufactured shape and is extremely biologi- cally inert. Metal stents may be covered or uncovered, the latter only suitable for extrinsic compressive stenosis. They are placed using an applicator passed over a guidewire, then accurately released in the required posi tion within the airway. \200 \200 The effect on endobronchial tumors is delayed but pro- gressive and potentially durable. Br achytherapy should be available on a regional or network basis as part of the multidiscipli nary management of lung cancer. Photodynamic therapy (PDT) The word \200\230photodynamic \200\231 means pertaining or rela ting to the energy of light, and in a clinical setting implies a tissue- toxic response to light. An intravenous sensitiser is \201 rst administered, most frequently the porphyrin derivative, Por \201 mer sodium. It is selectively taken up by tumor tissue. Exposure of p hoto-sensitized tissue to laser light of an appropriate wavelength causes the release of hi ghly active singlet-oxygen radicals which cause tumor cell death by thromboxane release, re sulting in ischaemic necrosis. \200 \200 May be life saving in critical tracheal obstruction. Useful to stabilize an airway prior to radiotherapy or other treatment which would otherwise be hazardous. Should not be regarded as a substitute for de \201 nitive tumor-reducing therapy. Complications include infectio n, granulation, and stent migration. Uncovered metal stents rapidly embed and epithelialise and therefore cannot be removed; they are to be used with caution in non-malignant disease . Late stent fracture has been reported. A \202 exible or rigid bronchoscope can be used. Laser light is delivered by a radial dif fuser or a forward- projecting microlens, attached to a \202 exible light guide. Produces a local anti-tumor effect with minimal toxicity to surrounding tissue. Porfimer sodium is administered intravenously at a dosage of 2mg per kg. Illumination is generated by a Diode laser at 630 nm. The recommended dosage using a cylindrical diffuser is 200 Joules/cm, 100 Joules per cm2 using the microlens. A typical treatment, using a 2.5cm diffuser, takes arou nd 8 minutes to deliver. Can be used to debulk large obstructing tumors and to eradicate in situ and micro-invasive disease. The principal drawback is light sensitisation due to accu - mulation of the systemic sensitiser in skin. Light protec- tion is required for up to eig ht weeks. Other complications include large-airway obstruction from tumor necrosis, occasio nal hemorrhage, and late \201 brotic stricture. Interventional bronchoscopy techniques can be used singly or in combination and should be c onsidered along with standard methods of tumor-reducing therapy. They are best delivered as part of a multidisciplinary airway manage- ment service, perhaps involving more than one t reatment center but available on a regional or network basis. Selec- tion of the appropriat e technique (or combination of techniques), for a given patient and clinical situation, is of paramount importance. \200 Further reading Barber P, Barr H, George J, et al. Photodynamic therapy in the treat- ment of lung and oesophageal cancers. Clinical Oncology 2002; 14: 110 \200\223116. Barber P, Stout R. High dose rate endobronchial brachytherapy for the treatment of lung can cer: current status and indications. Invited editorial, Thorax 1996; 51: 345 \200\223347. Ernst, Feller-Kopman D, Becker HD, et al. Central airway obstruc- tion. Am J Crit Care Med 2004; 169: 1278 \200\2231297. Herth, Eberhardt R, Ernst A, et al. The future of bronchoscopy in diagnosing, staging and t reatment of lung cancer. Respiration 2006: 73: 4. Both brachytherapy and PDT offer the attractive option of potential cure in early central l ung cancer without major loss of lung tissue. Careful post-treatment surveillance is requir ed however, and may be assisted by the use of fluorescence bronchoscopy to identify and del ineate recurrent/progressive disease. Saad, Murthy S, Krizmanich G, et al. Self-expandable metallic airway stents and \202 exib le bronchoscopy. Chest 2003: 124: 1993 \200\2231999. Sutedja, Venmans BJ, Smit EF, et al. F luorescence bronchoscopy for early detection of lung cancer. A clinical perspective. Lung C ancer 2001; 34(2): 157 \200\223168. Stenting Tracheobronchial stents are hollow prostheses used to maintain or restore airway p atency in malignant (and occasionally non-malignant) airway obstruction. This page intentionally left blank 321 Chapter 14 Pleural disease Chapter contents 14.1 Normal physiologic \202 uid volume and cellular contents 322 14.2 Assessment and inv estigation of an undiagnosed pleural effusion (including thoracoscopy) 326 14.3 Pneumothorax 332 14.4 Exudative pleural effusions (excluding malignancy) 338 14.5 Tran sudative pleural effusions 340 14.6 Malignant effusions 342 14.7 Malignant mesothelioma 346 14.8 Pleural effusions in systemic disease 350 14.9 Pleural infection 352 14.10 Surgery fo r pleural diseases 356 M NOPPEN 322 14.1 Normal physiologic \202 uid volume and cellular contents In normal conditions, the pleural space contains a small amount of pleural \202 uid. This small volume of pleural \202 uid is maintained in the pleural space by a complex interpl ay of hydrostatic pressures and lymphatic drainage, which allows for steady liquid and prot ein turnover. Pathological processes may lead to the development of pleural effusions by ca using disequilibrium between the rates of pleural \202 uid formation, pleural permeabilit y, and pleural \202 uid absorption. The focus here is on the normal pleural \202 uid vo lume, cellular and solute content in normal, physiological circumstances. Normal pleural \202 uid is a mi- crosvascular \201 ltrate; its volume and composition are tightly contro lled. Liquid enters the pleural space through the pa- rietal pleura down a net \201 lteri ng pressure gradient, and is removed by an absorptive pressure gradient through the viscera l pleura, by lymphatic drainage through parietal pleura stomas, and by cellular mechanisms (active trans- port of solutes by mesothelial cells. The main function of the normal pleura l \202 uid is thought to be lubrication of the pleural surfaces, enabling transmission of the forces of breathing between the lung and the chest wall. Together with the presence of subatmospheric pressures within the pleural space, this lubrication function enables respi ratory movements by a mechanical coupling between lung and chest wall. This lubrication fun ction is supported by the presence of surfactant lipids in normal pleural \202 uid, which are ef \201 cient in terms of boundary lubrication and adherence to biological surfaces, and of hyaluran. Most of what is known about the volume, composition, and dynamics of norma l pleural \202 uid has been obtained from animal studies. Retrieval of the few mililiters of normal pluid \202 uid in humans indeed is dif \201 cult without traumatically distur bing the pleural space: there- fore, only a few human studies are available. collection in rabbits: aspiration of the free \202 uid versus ir- rigation with 10 ml Han ks solution. The total volume of aspirated pleural \202 uid volume for both pleural space s was 0.45 0.12 ml (0.13 ml.kg-1). Total white blood cell count for the original aspirat ed \202 uid was 1503 281 cells. L-1. Differential cell counts varied with the differen t methods of \201 xation (95% alcohol and Papinacolaou stain versus 50% alcohol, 1% polye thylene glycol, and Papinicolaou stain) between 38.6 and 70.1% monocytes, 10 and 10.6% lym- phocytes, and 5.5 and 16.6 macrophages. Sahn et al aspi- rated costodiaphragmatic \202 u id in rabbits. Total volume of the free pleural \202 uid in both pleural spaces was 0.45 0.90 ml (0.13 ml.kg-1). Total white blood cell count was 1503 414 cells. L-1, with 7 0.1 3.6% monocytes, 10.6 1.8% lymphocytes, 8.9 1.6% mesothelial cells and 7.5 1 .5% macrophages. Novakov et al performed aspiration and lav- age in rabbits. Volumes and to tal white blood cell counts were not reported; differential cell counts included 9.25% macr ophages, 66.5% monocytes, 8 % mesothelial cells, and 9.75% lymphocytes after aspiration, an d 5% macrophages, 60.17% monocytes, 10% mesothelial cells, and 11.08% lym- phocytes after l avage. Other measurements of pleural \202 uid volume have been made by Broaddus, Wang, an d Agostoni in rabbits, Mellins in dogs, Wiener-Kronish, and Broaddus in sheep and Miserocch i in various animal models (cats, puppies, dogs, cats, and pigs), as part of studies for ot her purposes than actual volume measurements. All measure- ments (except those in puppies) yielded total volumes between 0.04 and 0.28 ml.kg-1. The solute composition of normal pleur al \202 uid is similar to that of interstitial \202 uid of other organs and contains 1 to 2 grams of protein 100 ml-1, mainly consisting of albumin (50%), globulins (35%) and \201 brinogen. Levels of large mo- lecular weight proteins such as lactate dehydrogenase in the pleural \202 uid are less than half of that found in serum. Animal studies Data derived from animal studies are summarized in Table 14.1.1. Although th ere is a certain degree of concordance as to the total volume and total white blood cell co unt of normal rabbit and dog pleural \202 uid, there is a large dispar- ity between the v arious differential cell counts between the various animal models. The reasons for this dis parity include differences in identi \201 cation of and distinction be- tween macrophages, monocytes and mesothelial cells, and methodological differences in \201 xation, staining and \202 uid retrieval techniques (aspiration or lavage), and possible genuine interspec ies differences. Miserocchi and Agostoni collected pleural \202 uid from the costodiaphra gmatic sinuses of rabbits and dogs. In rabbits, 0.46 ml of free \202 uid could be retriev ed from both pleural spaces (0.2 ml.kg-1). In dogs, 0.55 ml or 0.15 ml.kg-1 could be collec ted. When the volume of \202 uid adherent to the lung surfaces was assessed and included, volumes of pleu- ral \202 uid rose to 0.4 ml.kg-1 and 0.26 ml.kg-1 respectively. Total a nd differential white blood cell counts were per- formed using a cell counting chamber and May-Gzunwald- Giemsa stained cell smears. In rabbits, 2442 595 cell. L-1 were present inc luding 31.8% mesothelial cells, 60.8% monocytes, and 7.4% lymphocytes. In dogs, 2208 734 c ells. L-1 were present, including 69.6% mesothelial cells, 28.2% monocytes, and 2.2% lymp hocytes. Stauffer et al compared different cytopreparations and different methods of \202 uid Human studies Reliable data on the volume and cellular content of pleural \202 uid in nor mal humans are scarse, because of the obvious dif \201 culties in retrieving this small am ount of \202 uid without \200\230disturbing \200\231 the pleural environment. The \201 rst study ad- dressing this issue was that of Yamada, published in 1933, who punctured the 9th or 10th intercostal space on the dorsal axillary line in a group of healthy Japanese s oldiers. In about 30% of cases some \202 uid was aspirated after a period of rest, wherea s in about 70% of cases some \202 uid was retrieved after exercise. Usually only a few dr ops of foam was aspirated but in a few cases up to 20 ml could be retrieved. Total white bl ood cell count was 4500 L-1 (range 1700 \200\223 6200). Differential cell count showed 5 3.7% cells similar to monocytes, 10.2% lymphocytes, 3% meso- thelial cells, 3.6% granulocyt es, and 29.5% \200\230deteriorated cels of dif \201 cult classi \201 cation \200\231. Mo re recently, a pleural lavage technique was used to retrieve the few milliliters of pleural \202 uid present in the pleural space of otherwise healthy participants undergoing thora coscopic sympathec- tomy for the treatment of essential hyperhidrosis. In anal- ogy with br onchoalveolar lavage (a technique enabling retrieval of small volumes of epithelial lining \202 uid from the lung), 150 ml of prewarmed saline was injected in, and immediately aspi rated from the right pleural space, after induction of a pneumothorax in the setting of a t horaco- scopic sympathectomy performed for the treatment of CHAPTER 14.1 Normal physiologic \202 uid volume and cellular contents CHAPTER 00 CHAPTER TITLE 323 Table 14.1.1 Species Mean volume (right & left pleural space) ml.kg-1 Total white blood cell count, L-1 Macrophages (%) Monocytes (%) Mesothelial Cells (%) Lymphocytes (%) Rabbits 0.2 2442 595 NR 60.8 31.8 7.4 Dogs 0.15 2208 734 NR 28.2 69.8 8.2 Rabbits 0.13 1503 281 7.6 to 16 38.6 to 70.1 3.7 to 25.4 10 to 10.6 Rabbits 0.13 1503 414 7.5 1.5 70.1 3.6 8.9 1.6 10.6 1.8 Rabbits NR NR 9.25 66.5 8 9.75 Rabbits NR NR 5 60.17 10 11 Rabbits 0.1 1216 800 NR NR NR NR Rabbits 0.09 NR NR NR NR NR Rabbits 0.22 NR NR NR NR NR Dogs 0.1 NR NR NR NR NR Sheep 0.12 NR NR NR NR NR Sheep 0.04 NR NR NR NR NR Rats 0.6 NR NR NR NR NR Puppies 1.33 NR NR NR NR NR Cats 0.28 NR NR NR NR NR Pigs 0.22 NR NR NR NR NR essential hyperhidrosis. With urea used as an endogeneous marker of dilution, measured mean right-sided pleural \202 uid volume was 8.4 4.3 ml. In a subgroup of subjects, right- and leftsided pleural \202 uid volumes were shown to be similar. Expressed per kg of bod y mass, total pleural \202 uid volume in non-smoking, healthy subjects is 0.26 ml.kg-1, w hich corresponds well with values obtained in animal studies. Total white blood cell count in the pleural \202 uid of normal non-smoking subjects was 1716 cells L-1. Differ- enti al cell count yielded a predominance of macrophages (median 75%, interquartile range 16%) a nd lymphocytes (median 23%, interquartile range 18%). Mesothelial cells, neutrophils, and e osinophils were only marginally present. A typical image of a cell smear is shown in Fig. 1 4.1.1. In a second study using a similar lavage technique, lymphocyte subtyping showed a lo wer proportion of CD4 positive T cells (30% vs 45.8 %) and a higher proportion of CD8 posti tve T cells (11.78 vs 9.6 %) and regulatory T cells (CD4+CD25high) in pleural \202 uid in normal subjects as compared to blood which may suggest that previously described abnormali ties in lymphocyte subsets in pleural effusions may not only be a result of the pleural dis ease itself but also be characteristic of the pleural compartment itself. Interestingly, a small but statistically signi \201 cant in- crease in pleural \202 uid neutrophils was o bserved in smoking subjects. In addition to revealing the volume and cellular composition o f normal pleural \202 uid (which may be helpful in understanding cellular events occurrin g in disorders characterized by pleural effusions), this pleural lavage tech- nique allows to study the pathophysiological events in pleural disorders which typically are not associa ted with pleural effusions, such as pneumothorax and asbestos- related pleurisy. Fig. 14.1.1 A typical cell smear of a pleural lavage sample in a normal, non-smoking subjec t. M NOPPEN 324 Miserocchi G, Agostoni E. Contents of pleural space. J Appl Physiol KEY ISSUES \200 1971; 30: 208 \200\223213S. In normal animals and humans, the pleural space con- tains a small volume of pleural \202 uid. In different animal species this volume varies between 0.04 and 0.20 ml.kg-1. In norm al humans, the pleural \202 uid volume is 0.26ml.kg-1. This \202 uid has the solute cha racteristics of all intersti- tial \202 uids, and contains a total of 1000 to 2500 white blood cells per L. Macrophages/monocytes and lym- phocytes are the predominant cell types . Pleural lavage is a safe and simple technique allowing the study of normal pleural \202 uid, and of pleural dis- ease which is not characterized by pleural effusions. Miserocchi G. Physiology and pathophysiology of pleural \202 uid turnover. Eur Respir J 1997; 10: 219 \200\223225. Noppen M, De Waele M, Li R, et al. Volume and cellular content of normal pleural \202 uid in humans examined by pleural lavage. Am J Respir Crit Care Med 2001;7:180 \200\223182. Noppen M, Herregodts P, D \200\231haese J, et al. A simpli \201 ed thoracosco- pic sympath icolysis technique for essential hyperhidrosis: results in 100 consecutive patients. J Lapa roendosc Surg 1996; 6:151 \200\223159. Noppen M. Normal volume and cellular contents of ple ural \202 uid. Curr Opin Pulm Med 2001;7:180 \200\223182. Further reading Broaddus VC, Araya M, Carlton DP, et al. Developmental changes in pleural l iquid protein concentration in sheep. Am Rev Respir Dis 1991; 143: 38 \200\22341. MiserocchiG, Negrini D, Mortola J. Comparative features of Starling-lymphatic interaction a t the pleural level in mammals. J Appl Physiol 1984; 56:1151-1156. This page intentionally left blank H DAVIES & R DAVIES 326 14.2 Assessment and investigation of an undiagnosed pleural effusion (including thoracoscop y)