Bungay HK et al. An evaluation of CT as an aid to diagnosing patients undergoing bronchosco py for suspected bronchial carcinoma. Clin Radiol 2000; 55(7): 554 \200\22360 Laroche C et al. Role of CT scanning of the thorax prior to bronchoscopy in the investigati on of suspected lung cancer. Thorax 2000; 55(5): 359 \200\22363 Ernst A et al. Effect of routine clopidogrel use on bleeding complications after TBB in hum ans. Chest 2006; 129: 734 \200\2237. CHAPTER 64 Bronchoscopy 748 Patient preparation and procedure Patient preparation \200 Information Patients should be given written information about the procedure ideally more t han 24 h prior to the procedure. Provide an information sheet for the patient to take home following the bronchos- copy, with advice about the effects of any sedation and possible co mpli- cations, as well as telephone numbers in case help is needed Consent The physician pe rforming the bronchoscopy should obtain written consent, with a description of the procedur e and its associated risks Nil by mouth Patients should have no food for 4 h beforehand and clear \202 uids only until 2 h beforehand Blood tests Patients do not need routine pre-p rocedure blood tests, unless there are speci \201 c concerns (uraemia, deranged LFTs, low plate- lets). Many physicians check platelet counts and clotting times prior to transbronch ial biopsy (platelets >75 000/mm3, PT, and APTT within 1 \200\2232 s of control) and warfar in/heparin/low molecular weight heparin may be temporarily stopped Bedside tests Consider p erforming an ECG in patients with a history of cardiac disease. Check blood sugar in patien ts with diabetes Prophylactic antibiotics recommended in those at risk of endocarditis, i.e . asplenic, heart valve prosthesis, previous infective endocarditis: amoxicillin 3 g PO 1 h pre-bronchoscopy, or if penicillin allergic, clindamycin 600 mg PO or azithromycin 200 mg PO. Recent guidelines, however, from British Society of Antimicrobial Chemotherapy suggest this is not necessary (Gould FK et al. J Antimicrob Chemother 2006; 57: 1035 \200\22342) In those with asthma, a nebulized bronchodilator should be given before the bronchoscopy Thos e at high risk of infection (TB) should be last on the list. Procedure \200 Practices vary between centers. Some perform bronchoscopy with the patient sitting up facin g the operator; some from behind with the patient lying \202 at IV access should be prese nt in all patients Nasal oxygen should be administered and oximetry measured throughout Pre medication may be given in addition for mild sedation, anxiolysis, and anterograde amnesia. A benzodiazepine such as midazolam 2 mg, with 1 mg increments as necessary, may be used wi th fentanyl. Some patients and operators prefer not to use sedation, due to concerns partic ularly in elderly patients, those with COPD, or those with cardiac disease. Midazolam can m ake some patients more agitated. Premedication with anticholinergics is not bene \201 cial during bronchoscopy \200 PATIENT PREPARATION AND PROCEDURE 749 Lidocaine Local anesthetic spray or gel is applied to the nostrils and the vocal cords are anesthetized by spraying local anesthetic (lido- caine 10 mg/spray) to the back of the thro at and allowing time to work. Peak plasma levels occur after 15 min. \200 Transcricoid injection may be used to administer 4% lidocaine into the trachea, or this may be anesthetized under direct vision through the bronchoscope, when the vocal cords are ope n Aliquots of 1 \200\2232% lidocaine may be administered to right and left main bronchi via the bronchoscope when it is passed through the vocal cords into the trachea. Use the minim al dose required for cough suppression. Peak plasma levels occur after 5 min via the scope. Airway in \202 ammation increases lidocaine absorption Maximum dose of lidocaine is 8 mg/ kg (= 29 mL of 2% solution in 70 kg patient); 5 mg/kg if hepatic or cardiac insuf \201 cie ncy. Toxic effects include seizures and arrhythmias The half-life of lidocaine is 1.5 \200 \2232 h Most access the trachea via the nasal route, as this gives increased sta- bility when takin g biopsies and allows the patient to cough and spit out secretions more easily. If this is not possible, a mouth guard is used and access obtained through the mouth All sections of t he bronchial tree should be visually inspected, including the cords and trachea. CXR or CT may help localize the area of concern so specimen site can then be targeted. This increases the diagnostic yield of bronchoscopy in cases of suspected lung cancer Avoid unnecessary s uction, as this can increase hypoxia. CHAPTER 64 Bronchoscopy 750 Sampling techniques Bronchial washings are taken by instilling about 10 mL of saline and th en collecting it in a pot/trap to obtain super \201 cial airway cells. Bronchial brushings are taken by inserting a covered brush into a bronchial segment, uncovering it, rubbing th e bronchial wall, covering it, removing it, and wiping it on a slide. The slide is then spr ayed with a cell \201 xing solution. Bronchial biopsies are taken with biopsy forceps. 5 \200\2237 should be taken to optimize yield. These may be taken blindly or from a visibly a bnormal area, which gives a higher diagnostic yield than blind biopsies. They can be placed in formalin or saline solution depending on whether they are for histology or microbiology . Bronchoalveolar lavage (BAL) is performed by inserting 50 \200\223100 mL of saline throug h the bronchoscope when it is wedged well in a small airway. Ideally instill \202 uid dur ing inspiration and, after allowing the \202 uid to dwell for 10 \200\22330 s, aspirate b ack into the syringe during expiration or collect in a trap. Best performed in the area of abnormality on CXR or CT, or non-dependent lobes such as the right middle lobe or lingula. Poor return if the patient is coughing excessively or if they have emphysema. Can cause hyp oxia proportional to amount of lavage \202 uid used. Transbronchial biopsy (TBB) Techniqu e of passing transbronchial biopsy forceps down a terminal bronchus until resistance is \201 rst felt and taking a sample of parenchymal tissue. Safe to perform if patient is taki ng aspirin or on subcutaneous heparin, but omit clopidogrel for 5 days before (as well as a spirin if taking both) and, if on warfarin, wait until INR <1.3. Some perform with radiolog ical screening. Associated with a signi \201 cant risk of bleeding in 9% and pneumothorax in 3.5%, but up to 14% if patient is mechanically ventilated. Half of all pneu- mothoraces require chest dr ains. Therefore perform on one side only and minimize risk by performing TBB in the lower l obes, in dependent seg- ments. Perform CXR 1 h after the bronchoscopy. Pneumothorax should be managed according to standard guidelines (p 376). Small pneumo- thoraces often resolve s pontaneously, but the patient may need admission if there are concerns. Transbronchial need le aspiration (TBNA) (see p 286) is used to sample mediastinal and hilar lymph nodes in sus pected malignancy, TB, or sarcoidosis. It is also useful in sampling extrabronchial masses or necrotic endobronchial tumor. When added to other sampling techniques in lung cancer, it increases the diagnostic yield by 18%. When performing bronchoscopy \200 Wear gloves, face mask and eye shields \200 Use parti culate (duck) masks if there are concerns about TB or HIV SAMPLING TECHNIQUES 751 Superior Mediastinal Nodes Brachiocephalic (innominate) a. 1 1 Highest Mediastinal 2 Upper Paratracheal 2R 3 Pre-vascular and Retrotracheal Ao 4R Azygos v. 4 Lower Paratracheal (including Azygos Nodes) N2=single digit, ipsilateral N3=single digit, contralateral or supraclavicular 4L 10R PA 7 11R Aortic Nodes 11L 5 Subaortic (A-P window) 10L 8 6 Para-aortic (ascending aorta or phrenic 9 12,13,14R 12,13,14L Inf.pulm.ligt. Inferior Mediastinal Nodes 7 Subcarinal 8 Paraesophageal (below carina) 3 Ligamentum arteriosum 9 Pulmonary Ligament L.pulmonary a. Phrenic n. 6 N1 Nodes 10 Hilar Ao 5 11 Interlobar PA 12 Lobar 13 Segmental 14 Subsegmental Fig. 64.1 Mediastinal lymph node stations. Reproduced with the kind permission of the Ameri can College of Chest Physicians. CHAPTER 64 Bronchoscopy 752 Central airway obstruction (see also upper airway obstruction, p 640) Central airway = trac hea and mainstem bronchi Obstruction can be: \200 \200 \200 Extrinsic, such as tumor pressing on airway causing obstruction Intrinsic, such as tumor oc cluding airway lumen Mixed, a combination of extrinsic and intrinsic Symptoms and signs \200 \200 \200 \200 \200 \200 May be asymptomatic if obstruction is mild Productive cough, due to mucosal swelling and mu cous production Wheeze, unilateral wheeze, positional wheeze Stridor Secondary atelectasis and pneumonia Dyspnoea Investigations \200 \200 \200 \200 Flow \200\223volume loops, FEV1 CXR \200\224may be normal CT chest + 3D airway reconstructi on if possible Bronchoscopy to make tissue diagnosis of underlying disease Treatment \200 \200 Secure airway Consider bronchoscopy \200\223 senior physician anesthetist should perfor m. Bronchoscopy itself can cause obstruction in a compromised airway. Adrenaline administer ed via bronchoscope may be helpful Consider endobronchial treatment: core out tumor, dilate a stenosis, or place a stent (see p 755) Consider heliox (see p 641) Causes of central airway obstruction \200 Malignant \200 \200 \200 \200 \200 \200 Primary endoluminal cancer, especially lung cancer or carcinoid Metastatic cancer Laryngeal cancer Oesphageal cancer Mediastinal tumor Lymphadenopathy, lymphoma CENTRAL AIRWAY OBSTRUCTION 753 Non-malignant \200 \200 \200 \200 \200 \200 \200 \200 \200 \200 Lymphadenopathy Relapsing polychondritis Tracheomalacia Papilloma Hamartoma Amyloid Web Goi ter Foreign body Granulation tissue Further information Ernst A et al. Central airway obstruction. Am J Respir Crit Care Med 20 04; 169: 1278 \200\22397 Janssen JP et al. Series: Interventional pulmonology. Eur Respir J 2006; 27: 1258 \200\2237 1; 28: 200 \200\22318 Wood DE et al. Airway stenting for malignant and benign tracheobronchial stenosis. Ann Thor ac Surg 2003; 76: 167 \200\22374 ERS/ATS Statement on Interventional Pulmonology. Europ Respir J 2002; 19: 356 \200\22373 CHAPTER 64 Bronchoscopy 754 Interventional bronchoscopy Used particularly in the diagnosis and palliative treatment of patients with lung cancer and central airway obstruction due to local tumor growth, where t he relief of the obstruction will have symptomatic bene \201 ts. Diagnostic procedures Transbronchial needle aspiration and endobronchial ultrasound allow m ediastinal node sampling without the surgical procedure of mediastinos- copy. Some lymph no des are accessible for sampling in this way, which cannot be accessed via mediastinoscopy. Transbronchial needle aspirate (TBNA) Technique of inserting a biopsy needle blindly throug h the bronchial wall into an enlarged lymph node or extrab- ronchial mass, and aspirating c ells. Used to give additional staging informa- tion in lung cancer. Appropriate lymph nodes should be identi \201 ed on CT \201 rst. Should be performed initially, so the bronchos cope is not contami- nated with malignant cells from the airway, and start with the highest -stage lymph nodes \201 rst. Push sheath out through end of bronchoscope until the hub is just visible. Extend the needle and then position over nodal position and insert through b ronchial wall. Subcarinal and right hilar nodes are the easiest to sample. Aim for 5 \200 \2237 needle passes. Endobronchial ultrasound (EBUS) Technique of visualizing the bronchial wall and the immediate surrounding structures via an ultrasound probe either incorporated into the tip of the bronchoscope or passed down the scope. A balloon surrounding the probe is in \202 ated with water, in order to achieve close circular contact and view surroundin g structures. Useful to assess lymph node involvement in malignancy and to guide TBNA: left and right paratracheal, carinal, subcarinal and some hilar nodes can be assessed. Mediasti nal structures or masses next to the airways can be identi \201 ed, the depth of bronchial wall tumor invasion assessed, or masses within the lung localized for biopsy. RCT shows im proved yield compared with \200\230blind \200\231 TBNA. Oesophageal endoscopic ultrasound (EUS) is an alternative strategy, which allows examination of the posterior and inferior me diastinum, the liver, the coeliac axis, and the left adrenal gland. It is more accurate at diagnosing mediastinal metastases than CT and PET. Auto \202 uorescent bronchoscopy (AFB) Technique to differentiate central malignant areas from normal tissue, including dysplasia and pre-invasive tumors in situ. However, the progression of these abnormalities is not kno wn, so the role of AFB is unclear. Used in conjunction with usual white light bronchoscopy. Uses blue light to induce tissue auto \202 uorescence, which means normal and abnormal ti ssues appear different colors when viewed through a specialized bronchoscope. Airway trauma , however, can also cause a different mucosal appearance and the test has low speci \201 c ity. It is being used in some centers as a surveillance tool following surgical resection o f lung cancer, or in patients with head and neck cancer sus- pected of having a lung primar y, or following positive sputum cytology. Its role is not, however, clear and advances in s tandard white light broncho- scopes (such as using narrow band imaging) may be found to be as good at identifying abnormal mucosa. INTERVENTIONAL BRONCHOSCOPY 755 Rigid bronchoscopy Visualize bronchial tree to level of segmental bronchi. Can remove or co re out endobronchial tumors, insert a stent, dilate tracheal or bronchial stenosis, and man age massive haemoptysis. Useful to provide information regarding resectability in lung canc er by measuring airway length. Incidence of serious complications <5%: hypoxia, laryngospas m, pneumot- horax, bleeding. Therapeutic procedures Bronchial laser resection, electrocautery, argon \200\223plasma coag ulation, photodynamic therapy (PDT) and cryotherapy These are all procedures that can be us ed to debulk obstructing endobronchial lesions or coagu- late a bleeding point. Electrocaut ery is the use of an electrical current via a probe to heat tissue, causing coagulational v aporization, which enables cutting. Laser achieves the same effect. These are used predomin antly for obstructing malignant lesions, but may be used to remove benign lesions, e.g. pap illoma, or to treat benign stenoses, e.g. due to intubation, sar- coidosis, Wegener \200 \231s, trauma, etc. Avoid using FiO2 >40% with both laser and electrocautery, to minimize t he \201 re risk. Shave skin on thigh if nec- essary before placing electrode for electroc autery and avoid placing it over metal prosthetic joints. Argon \200\223plasma coagulation is a non-contact method using argon gas. These are all effective immediately. Cryotherapy i s the technique of freezing and then thawing an area with a probe in order to destroy tissu e, such as an endobronchial obstructing lesion. It takes hours \200\223days to have its eff ects. It can also be used to remove a foreign body, as freezing attaches foreign body to th e end of the probe. Photodynamic therapy Intravenous administration of a photosensitizer dr ug to the patient, followed by bronchoscopic exposure of the pre- sensitized tumor to a lig ht of speci \201 c matching wavelength in order to cause tumor necrosis. Airways cleared o f debris immediately after and again a few days later. Bronchial stent insertion via the br onchoscope to re-establish airway patency if there is extrinsic compression. Self-expanding metal stents used in cases of external compression, such as lung cancer, for pallia- tion of breathlessness. These are inserted over a guidewire with \202 exible bronchoscopic vis ualization. Repositioning can be tricky after placement. Retained secretions can cause sten t blockage. Silicone stents are used in mainly benign disease and are inserted via rigid br onchoscopy. They are easily removed and maneuvered, but can migrate and lead to problems wi th retained secretions. Brachytherapy Procedure of endobronchial irradiation using iridium- 192 via bronchoscope for endobronchial and intramural tumors. The radio- active source can be implanted into the tumor. Delayed effect, requires several sessions. Complementary to ot her bronchoscopic therapies. Can cause \201 stulas and hemorrhage. This page intentionally left blank 757 Chapter 65 Chest drains Indications, drain types, complications 758 Insertion technique 760 Drain management 762 CHAPTER 65 Chest drains 758 Indications, drain types, complications Chest drain insertion is associated with signi \201 cant morbidity and mor- tality, and careful consideration should be given to the preci se indication for drainage. Ultrasound guidance may be required for small or loculated effu sions (e.g. empyema). Indications \200 \200 Tension pneumothorax (following needle decompression) Symptomatic pneumothorax with failed aspiration or underlying lung disease Complicated parapneumonic effusion and empyema Malign ant pleural effusion for symptomatic relief and/or pleurodesis Haemothorax Traumatic haemop neumothorax Rarely, for symptomatic effusions of other etiology. \200 \200 \200 \200 Contraindications \200 \200 \200 Inexperienced operator Lung adherent to chest wall Bleeding tendency (a relative contraindi cation; routine measurement of platelet count and clotting in the absence of risk factors i s not required) Post-pneumonectomy (not a contraindication, but discuss with cardio- thorac ic surgical team; imaging may be required for drain placement). Types of chest drain Tradit ional trocar drains consist of a \202 exible plastic tube surrounding a metal rod with a blunt tip and are available in a variety of sizes. When inserted incorrectly or with excess force by an inexpe- rienced operator, they can cause signi \201 cant harm and even death. Blue portex drains are inserted over a \202 exible plastic introducer in a similar manne r to trocar drains; they are available in a range of sizes, up to 28F. Newer Seldinger-styl e drains involve sliding the drain into the pleural cavity over a guidewire. They are safer than trocar drains, but still require experience and care to be inserted safely and comfor tably. Small (10 \200\22314F) drains are more comfortable and are adequate for the majority of sit- uations. Large bore chest drains (28 \200\22332F) are only rarely required, e.g. s econdary pneumothorax with large air leak and/or surgical emphysema, acute haemothorax. Complications \200 \200 Pain \200\224very common. Opiate analgesia frequently required Inadequate drain position \200\224may require withdrawal or insertion of new drain Surgical emphysema (in pneumothora x) \200\224air leaks into subcutaneous tissues. May occur if tube blocked or positioned wit h holes subcutane- ously, or with very large air leaks. See p 383 for management Infection \200\224empyema rate around 1%, perhaps higher in trauma patients Organ damage (e.g. lung, liver, spleen, heart, great vessels, stomach) \200\224 particularly if sharp trocar used. I ntrapulmonary placement results in signi \201 cant continuous bubbling and bleeding; this may occur in up to \200 INDICATIONS, DRAIN TYPES, COMPLICATIONS 759 6% of all drain insertions. Drainage of gastrointestinal contents suggests bowel perforatio n (or oesophageal rupture as the cause of the effusion) Hemorrhage into drain \200\224blood y pleural \202 uid is a common \201 nding (e.g. in malignant effusions), but unexpected large volume drainage of frank blood suggests damage to organs or intercostal vessels. Cla mp the drain and leave it in place. Urgent imaging and surgical referral Re-expansion pulmo nary oedema (p 383) Vasovagal reaction Sudden death due to vagus nerve irritation reported. \200 \200 CHAPTER 65 Chest drains 760 Insertion technique An assistant is required. 1. Discuss procedure with patient and obtain written consent (unless emergency situation) 2. Insert IV cannula 3. Consider sedation (e.g. midazolam 2 \200\2235 mg IV or diamorphine 2.5 \200\2235 mg IV) with oxygen saturation monitoring; be cautious in patients with severe underlying lung disease or respiratory failure 4. Position patient lying with bed head at 30 , with insertion side of trunk rotated about 45 upwards, and arm on insertion side behind their head; stand behind the patient. Alternative position is with patient sitting forward, leaning over a table 5. Double-check correct side from chest examination and CXR 6. Choose insertion site: ideal ly within \200\230triangle of safety \200\231, which avoids major vessels and muscles (bou ndaries: anteriorly, anterior axillary line, and border of pectoralis major; posteriorly, p osterior axillary line inferiorly, horizontal to level of nipple in man or \201 fth inter costal space in woman). More posterolateral approaches are safe, but less comfortable for t he patient when lying; avoid posteromedial approaches close to spine, as intercostal artery drops medially to lie in mid-intercostal space 7. Sterile skin preparation. Wear sterile gloves and gown 8. In \201 ltrate skin, intercos tal muscle, and parietal pleura with 10 mL of 1% lidocaine. Aim just above the upper border of the appropriate rib, avoiding the neurovas cular bundle that runs below each rib. The sub- cutaneous fat lacks pain receptors and does not require anesthetic. The parietal pleura, however, is extremely sensitive; use the full 10 mL of lidocaine 9. Verify that the site is correct by aspirating pleural \202 uid or air. Occasionally, a green (21G) needle may be too short in obese patients, and a longer needle is required. If unable to aspirate \202 uid or air, do not proceed with drain insertion; consider image- guided drainage 10. Whilst waiting for anesthetic to work, prepare drain and connections. Assistant should prepare underwater seal 11. Insert drain: Trocar drains Small (1-cm) skin incision parallel to rib. Consider horizontal mattress stit ch across incision to facilitate later closure. Dissect intercostal muscles with blunt forc eps (e.g. Spencer \200\223Wells) \200\224 the \201 bres can be teased apart by opening an d then removing the forceps; do not close forceps within the chest, this may damage underly ing structures. This blunt dissection may take some time. Insert trocar and drain smoothly and gently \200\224there should not be any signi \201 cant resistance. Never apply force w hen inserting a chest drain. Once the chest wall has been entered, withdraw the trocar a fe w centimeters and insert the drain into the pleural cavity. Never insert the trocar blindly into pleural cavity. An alternative approach is to remove the trocar and grip the end of t he chest tube with blunt forceps, and use these to guide the tube into the chest. Aim towar ds the apex for a pneumothorax, and the lung base for a pleural effusion INSERTION TECHNIQUE 761 (Note \200\224in emergencies, or in patients with extreme obesity or subcutaneous emphysema, it may be appropriate to make a larger initial incision and insert an index \201 nger to assist the drain track) Seldinger drains Gently insert the introduc er needle and check that air or \202 uid can be easily aspirated through it with a syring e. Remove syringe. Smoothly insert the guidewire through the introducer needle. Remove intr oducer needle. Slide plastic dilator around guidewire to enlarge the entry-track. Remove th e dilator and slide the drain into the pleural cavity over the guidewire. Do not let go of the guidewire at any time. Remove the wire when the drain is within the chest 12. Connect the drain to underwater seal bottle via a three-way tap and tubing. If the drain is correctly positioned in the pleural space it should swing in ti me with respiration, and drain air or \202 uid 13. Stitch and tape the drain in place on the chest wall 14. Ensure adequate analgesia 15. Warn the patient not to disconnect the tubing or lift the underwater bottle above the level of the insertion site on the chest; supply a \200\230chest drain information lea \202 et \200\231 16. Obtain CXR to check position. The \200\230ideal \200\231 tube position (apex for pneum othorax, base for effusion) is not necessary for effective drainage, so do not reposition f unctioning drains on this basis. CT may be useful in con \201 rming drain position in cert ain circumstances. Drains are often positioned in \201 ssures, but in most cases this doe s not affect their functioning 17. Small drains may need regular \202 ush to ensure potency; prescribe 10 mL normal saline \202 ush to drain tds Further information Laws D, et al. BTS guidelines for the insertion of a chest drain. Thora x 2003; 58(suppl. II): ii53 \200\2239 CHAPTER 65 Chest drains 762 Drain management General points \200 Patients should ideally be managed on a specialist ward by experienced nursing staff. \200 \230Chest drain observations \200\231 should be charted regularly, including swinging, bubb ling, and volume of \202 uid output If drain water level does not swing with respiration, the drain is kinked (check underneath dressing, as tube enters skin), blocked, clamped, or incorrectly positioned (drainage holes not in pleural space; check CXR). Occluded drains m ay sometimes be unblocked by a 30 mL saline \202 ush. Non-functioning drains should be re moved (risk of introducing infection) Suction is sometimes used to encourage drainage, alth ough there is a lack of evidence regarding its use. Consider in cases of pneumothorax with persistent air leak, or following chemical pleurodesis. Suction should be high volume/low p ressure, typically starting at a level of 5 cm H2O and increasing to 10 \200\22320 cm H2O. It is often painful and may not be tolerated by the patient. To clamp or not to clamp? Never clamp a bubbling chest drain (risk of tension pneumothorax) . Clamping may be considered in two situations: \200 To control the rate of drainage of a large pleural effusion. Rapid drainage of large volume s may result in re-expansion pulmonary oedema; clamping, e.g. for 1 h after draining 1 L, m ay prevent this To avoid inappropriate drain removal in cases of pneumothorax with a slow a ir leak, when bubbling appears to have ceased. Clamping of a drain for several hours follow ed by repeat CXR in such situations may detect very slow or intermittent air leaks. This is controversial, however, and should only ever be considered on a specialist ward with exper ienced nursing staff. If the patient becomes breathless, the drain should be immediately un clamped. Drain removal Quickly and smoothly remove the drain, whilst patient is breath-hold ing in expiration (although opinions on this differ \200\224some recommend removal in maxim al inspiration). Tie previ- ously placed mattress suture, if applicable. Apply dressing. CX R to document lung position. 763 Chapter 66 Cricothyroidotomy CHAPTER 66 Cricothyroidotomy 764 Indication In some situations of upper airway obstruction or facial trauma, ventila- tion a nd tracheal intubation of a patient is impossible. It may therefore be necessary to create an immediate surgical airway below the level of obstruction. Cricothyroidotomy 3 Call for anesthetic and ENT help \200 Extend the head, with the patient lying \202 at. Place a pillow under the patient \200 \231s shoulders, not their head Identify cricothyroid membrane: soft triangular area above cricoid ring and below the thyroid cartilage. (Put your \201 ngers on the larynx and move them down to the soft area below, where you are aiming for). Clean with antiseptic swab Pu ncture the membrane in the midline with a large bore cannula (18G or larger). Remove the ne edle, attach a syringe, and aspirate air to con \201 rm correct position. Speci \201 c cr icothyroidotomy kits are available Angle the cannula downwards at 45 and advance. Ensure air can still be aspirated and then connect to high-pressure oxygen supply, with a Y connec tor if possible Occlude one limb of Y connector with a \201 nger until chest rises and th en release to allow exhalation, ideally via larynx. In \202 ate for 1 s and de \202 ate f or 4 s. Must allow air to be exhaled. If there is no Y con- nector, a hole is cut in the ox ygen tubing, which can be intermittently occluded Secure the cannula Perform a formal surgi cal cricothyroidotomy with ENT help, as needle method does not allow adequate ventilation a s the tube is too small and the larynx is blocked. Vertical skin incision; press lateral ed ges outwards to minimize bleeding. Transverse cricothyroid mem- brane incision, take care n ot to damage cricoid cartilage. Dilate tract with tracheal spreader or scalpel handle, and insert a cuffed tube. \200 CRICOTHYROIDOTOMY 765 Fig. 66.1 Diagram of needle cricothyroidotomy. Reproduced from Wyatt et al. Oxford Handbook of Emergency Medicine 3e, 2006, with permission from Oxford University Press. Further information Advanced Life Support Provider Manual, 5th edn 2006. Resuscitation Coun cil UK This page intentionally left blank 767 Chapter 67 Miscellaneous diagnostic tests Skin prick tests 768 Technique of induced sputum 769 Methacholine challenge testing 769 768 CHAPTER 67 Miscellaneous diagnostic tests Skin prick tests These may be useful in identifying speci \201 c allergens causing immedia te hypersensitivity reactions. They may in \202 uence management and guide allergen avoida nce. They are also used to help de \201 ne atopy. Triggers in contact urticaria, atopic ec zema, and suspected food allergy may also be identi \201 ed. The results are available alm ost immediately (compared with a RAST test for speci \201 c IgE) and correlate well with R AST test results. They should be carried out by staff trained to read the tests and manage adverse reactions. The allergens tested should be identi \201 ed from the history, and usually include common aeroallergens, e.g. grass, house dust mite (Dermatophagoides pteronyssinus), and cat dande r. Practical points \200 \200 Testing should be performed off steroids and anti-histamines There is a very small risk of anaphylaxis; adrenaline and resuscitation equipment should be available. Particular care is needed with food and latex testing Put a drop of allergen on the skin (usually the inside forearm). A range of allergens are available commercially. Fresh produce should be used for suspected fruit and vegetable hypersensitivity Lance the skin through the allergen drop us ing a needle (do not draw blood). This should be with a calibrated lancet (1 mm), held vert ically, or a hypodermic needle held at 45 to the skin The positive control is usually his tamine, and the negative control the dilutent (usually saline) Read the test after 15 min A positive result is an itchy weal, which should be compared with the controls, as some subj ects react to the skin prick alone (dermatogra- phism) Test solutions are standardized to g ive a mean weal diameter of 6 mm A weal of 3 mm or more is considered positive (indicating allergen sensitization) A positive result does not prove that the clinical symptoms are due to bronchial hyperresponsiveness to the tested allergen, but do raise clinical suspicion. Positive results can occur in those without symptoms, and false negatives do occur. \200 \200 RAST or radio-allergosorbent blood tests are more speci \201 c, but less sensitive and mor e expensive than skin prick tests, but give similar infor- mation. There is no risk of anap hylaxis and the patient does not need to stop steroids or antihistamines for the test to be performed. Unconventional tests Electrodermal allergy testing (using a Vegatest machine) w as developed as an aid to homeopathic prescribing, and is widely used in complementary medi cine to assess allergic status to food and envi- ronmental allergens. It is based on small changes in skin electrical imped- ance at acupuncture points, in response to allergens plac ed in an electrical circuit. There are no RCT data to show that this method can identify at opic from non-atopic individuals, as identi \201 ed from skin prick tests. METHACHOLINE CHALLENGE TESTING 769 Technique of induced sputum \200 \200 Used to investigate for infection (e.g. TB, PCP) or airway in \202 ammation Patients rinse their mouth and clean their teeth to minimize oral con- tamination. Give inhaled salbutamo l, to minimize bronchoconstriction Nebulized hypertonic (2.7 \200\2235%) saline is administ ered via a face mask. Afterwards the patient expectorates sputum into a sterile pot If tran smission of infection (e.g. TB) is likely, perform the test in a nega- tive pressure room, with appropriate protection of staff and other patients. Do not perform on the open ward or out-patient department Send sputum promptly to microbiology for staining and culture, and direct immuno \202 uorescent testing for PCP (if indicated). Sputum for cell counts is mix ed with 0.1% dithiothreitol, diluted with saline, and then \201 ltered and centrifuged. Methacholine challenge testing \200 Methacholine induces bronchospasm in people with hyperreactive airways. Helpful if there is diagnostic doubt regarding the diagnosis of asthma Should be performed by experienced pers onnel, with facilities to deal with acute bronchospasm Increasing nebulized doses of methac holine are given systematically, with the FEV1 measured after each dose If there is a 20% f all in FEV1, or if the highest dose of methacholine has been given, the test is stopped The concentration of drug causing the 20% fall is known as the PC20 Asthma is indicated by a P C20 < 8 mg/mL. Normal subjects have a PC20 >16 mg/mL. \200 This page intentionally left blank 771 Chapter 68 Pleural biopsy 772 CHAPTER 68 Pleural biopsy Indications for Abrams \200\231 pleural biopsy \200 Diagnosis of tuberculous pleural effu sion \200 Abrams \200\231 biopsy is used for the diagnosis of malignant pleural disease i n many centers, although a recent randomized controlled trial has shown that CT-guided cutt ing-needle biopsy has a greater sensitivity (sensi- tivity 87% in CT-guided biopsy group vs . 47% in Abrams \200\231 group). Technique An assistant is required. 1. Discuss procedure with patient and obtain written co nsent 2. Insert IV cannula 3. Consider sedation (e.g. midazolam 2 \200\2235 mg IV, with oxy gen saturations monitoring) 4. Position patient sitting forward, leaning on a pillow over a table with their arms folded in front of them 5. Double-check correct side from chest examination and CXR 6. Choose biopsy site: 1 \200 \2232 intercostal spaces below upper level of effu- sion on percussion. Use posterior or lateral approach (although avoid very posterior approa ches close to spine, as intercostal artery drops medially to lie in mid-intercostal space) 7. Sterile skin preparation. Wear sterile gloves and gown 8. In \201 ltrate skin, intercos tal muscle, and parietal pleura with 10 mL of 1% lidocaine. Aim just above the upper border of the appropriate rib, avoiding the neurovas cular bundle that runs below each rib. Anesthetize area behind rib below the insertion poin t 9. Whilst waiting for anesthetic to work, assemble Abrams \200\231 reverse bevel biopsy nee dle. The needle consists of an outer sheath with a triangular opening (biopsy port) that ca n be opened or closed by rotating an inner sheath 10. Verify that the insertion site is correct by aspirating pleural \202 uid with a green (21G) needle. If unable to aspirate \202 uid, do not proceed 11. Make small (5 mm) skin incision; dissect intercostal muscles with blunt forceps (e.g. Spencer \200\223Wells) 12. Insert biopsy needle gently with biopsy port closed. Do not apply force; the needle should slip into the pleural space without resistance. When in the pleura l cavity, \202 uid can be withdrawn by attaching a syringe to the needle and opening the biopsy port 13. To take a biopsy, attach a syringe to the needle. Open the biopsy port and angle it dow nwards, and then pull the biopsy port \201 rmly against the parietal pleura on the rib be neath the entry point (6 o \200\231clock posi- tion relative to entry point). Close the bio psy port, thereby pulling a sample of parietal pleura into the needle 14. Remove the biopsy needle, open the biopsy port, and remove biopsy sample 15. Repeat procedure 4 \200\2236 times in positions 4 \200\2238 o \200\231clock, always sam pling below the insertion point (to avoid the neurovascular bundle beneath the rib above) 16. Send biopsy samples in saline for analysis for tuberculosis and in for- malin if malignancy is suspected PLEURAL BIOPSY 773 17. Apply dressing to biopsy site. May require a single stitch 18. CXR to exclude pneumotho rax. Complications include pain, pneumothorax, haemothorax, and empyema. Hemorrhage from tr auma to an intercostal artery may neces- sitate emergency thoracotomy. Fatalities are well documented, but rare. Further information Maskell NA et al. Standard pleural biopsy versus CT-guided cutting-need le biopsy for diagnosis of malignant disease in pleural effusions: a randomized controlled trial. Lancet 2003; 361: 1326 \200\22331. This page intentionally left blank 775 Chapter 69 Pleurodesis Chemical pleurodesis 776 776 CHAPTER 69 Pleurodesis The aim of pleurodesis is to seal the visceral pleura to the parietal pleura with adhesions to prevent pleural \202 uid or air accumulating. Successful pleurodesis is dependent upo n two factors. \200 Lung re-expansion following removal of pleural \202 uid or air, which allows the appositi on of visceral and parietal pleura. This may be encouraged by applying suction to an interc ostal drain In \202 ammation of the pleural surfaces, which is required to produce pleural \201 brosis and adhesions. This may be induced by a chemical scle- rosing agent or by pl eural abrasion at thoracoscopy. Indications \200 Recurrent and symptomatic pleural effusion (most commonly as a result of malignancy, althou gh pleurodesis is also rarely used in benign recurrent effusions) Recurrent pneumothorax (d ue to concerns regarding the long-term safety of intrapleural talc, surgical abrasion pleur odesis is usually the procedure of choice in younger patients; chemical pleurodesis may be used as a last resort in older patients who are un \201 t for surgery). Chemical pleurodesis Types of sclerosant Choice of sclerosing agents varies. The most com- monly used agents are sterile talc, tetracycline, and bleomycin. \200 Talc is the most effective (success rate about 90%), and can be adminis- tered either as a slurry via a chest drain or as a poudrage at thoracos- copy, but it carries a risk of induc ing ARDS (see later) Tetracycline is successful in about 65% cases Bleomycin has success ra tes of only 60%, and is expensive. \200 