.20, then the SaO2 falls to 70%. Increasing 2,3-DPG levels shift the curve to the right, bu t levels \202 uctuate unpredictably and any changes are small. Changes in body temperatur e are often the reason why measured pulse oximetry saturations apparently \200\230do not a gree \200\231 with the measured blood gasses (pH is taken into account in the theoretical c alculation of SaO2 by blood gas analysers, but the patient \200\231s correct body temperatu re is rarely entered and thus not taken into account). This is particularly important in hy pothermia when the curve is left shifted leading to impaired oxygen unloading anyway. Furth ermore, an apparently adequate oximetry reading can mask a low PaO2, which will further les sen oxygen availability to the tissues (although somewhat mitigated by the reduced metaboli c rate of hypothermic tissues). CO2 + H2O n HCO3 + H+ Removed by combination with Hb and other proteins Following small rises in PaCO2, the pH wo uld fall disas- trously without buffering of H+ ions. This buffering capacity depends mainl y on Hb (hence an estimate is made of Hb by the blood gas machine) and other proteins, prod ucing the normal buffer line running through (N) on the graph (Fig. 2.4.5). This line would be much \202 atter without buffering. Therefore acute hypoventilation and hyperventilati on will move the patient up and down this line, in directions b or c, respectively. If hypo ventilation at point b becomes chronic (e.g. as it may in COPD), then the kidney retains HC O3 (by excreting H+) to try and correct the pH towards nor- mal, and the patient moves on to a new iso HCO3 buffer line displaced to the right, e.g. the one labeled +10 meq/l (35 meq/l). The degree of displacement represents the metabolic component to the acid/base stat us and, in this case, because the [HCO3 ] has risen, will be higher than the normal \201 gure of about 25 meq/l. When the raised \201 g- ure is quoted relative to the normal 25 meq/l (by subtract- ing 25), this is called the \200\230base excess \200\231. Thus buffer lines to the right of the normal buffer line represent a metabolic alkalosis or base excess . These \201 gures are calculated assuming a normal or \200\230stand- ard \200\231 PaCO2 (i.e. not using the patient \200\231s real value), called Interpretation of arterial blood gasses \200\223 acid/ base balance Normal ranges pH 7.37 \200\2237.43 (H+ 37 \200\22343 nmol/l), PaCO2 4.6 \200\2235.9 kPa, base excess 3 mmol/l. CHAPTER 2.4 Interpretation of arterial blood gasses and acid/base balance 31 the \200\230standard bicarbonate \200\231 (SBC on the blood gas machine printout), or \200\230standard base excess \200\231 (usually SBE). Two other similar \201 gures on some printouts (usually HCO3 and TCO2) are calculated at the patient \200\231s actual PaCO2 a nd are not much use. They will be higher when the real PaCO2 is above normal (thus more HCO 3 made), and lower when below normal, as HCO3 will fall having com- bined with H+ to re place the CO2. Chronic hyperventilation (e.g. at altitude due to the hypoxia) produces the opposite, a resorption of [H+] by the kidney, and thus the buffer line shifts to the left g iving a negative value for the \200\230base excess \200\231, a \200\230base de \201 cit \200\231. Thus a metabolic acidosis compensates for a respiratory alkalosis. Note that thes e homeostatic corrections do not bring the pH back to normal as there needs to be an error signal to keep the correction process going. A metabolic acidosis (such as in ketoacidosis) will also move the line to the left (a), producing a base de \201 cit (or negative base e xcess \200\223 a curious invention!), followed by hyperventilation to try and correct the pH (i.e. a respira- tory alkalosis to correct a metabolic acidosis). This pure ventilatory stimulation in the absence of abnormal lungs often produces deep breathing with little incr ease in rate and is called Kussmaul \200\231s breathing. Thus lines to the left of the norm al buffer line represent a metabolic acidosis or base de \201 cit. A metabolic acidosis du e to anaerobic metabolism (and hence lactic acid production) can reverse the compensa- tory metabolic alkalosis secondary to chronic hypercapnia during a severely hypoxic COPD exacer bation, removing the evidence for chronic CO2 retention. Thus a fall in pH during a COPD ex acerbation re \202 ects not only impaired alveolar ventilation (increased airways obstruct ion) but also reduced PaO2 (anaerobic metabolism) \200\223 hence a low pH is the best guid e to how sick such a patient is. Finally, metabolic alkalosis e.g. during hypokalaemia (whe n the kidney is forced to use H+ ions, instead of potassium ions, to swap for the sodium th at needs resorbing from the tubular \202 uid, [H+] is lost in the urine and HCO3 return ed to the blood). This will move the buffer line to the right (d), but only limited hypoven tilation is available to compensate, due to the inevitable ventilatory stimulation that the attendant hypoxaemia produces. Thus the mixture of respiratory and metabolic contribu- tio ns to a patient \200\231s acid/base disturbance can be established by plotting the PaCO2 an d pH on the graph (Fig. 2.4.5). exist, and helps differentiate the cause of any metabolic acidosis. Depending on methods of measurement, the nor- mal value is between 8 and 16mmol/l (or meq/l) and mainly due to alb umin. A high anion gap indicates that there is loss of HCO3 without a subsequent increase in Cl . Electroneutrality is maintained by the increase in anions such as ketones, lactat e, PO4 , and SO4 . Because these ani- ons are not part of the anion-gap calculation a hig h anion gap results. An acidosis with a normal anion gap will be a simple HCO3 /Cl excha nge such as might occur, for example, in: \200 \200 \200 renal tubular acidosis; acetazolamide therapy; HCO3 loss from profuse diarrhea. An anion gap is likely to be present, for example, when the metabolic acidosis is due to: \200 \200 \200 \200 \200 \200 diabetic ketoacidosis (ketones are acids); renal failure (although can be in the normal ran ge too); lactic acidosis; salicylate poisoning; methanol poisoning; ethylene glycol (antifr eeze) poisoning. AUTHOR \200\231S TIPS There are only three main things to think about when assessing gas ex change: \200 \200 How much is the patient ventilating their alveoli? Is the PaO2 high enough to adequately ox ygenate tissues and thus prevent anaerobic metabolism? Is there any evidence of a V/Q misma tch, assessed from the A \200\223a gradient for oxygen? There are only three main things to think about when assessing acid/base: \200 Is there a ventilatory/respiratory contribution from an abnormally high or low PaCO2? Is th ere a metabolic component evidenced by a shift of the buffer line to the left or right, num erically the base excess (or de \201 cit)? If there is an acidosis, is there an increased anion gap? Further reading Williams AJ. http://www.bmj.com/cgi/content/ full/317/7167/1213 Anion gap The anion gap [(Na+ + K+) - (Cl + HCO3 )] shows you the amount of other anions , apart from Cl + HCO3 , that M MASOLI & P HUGHES 32 2.5 Respiratory muscle function Overview of function \200 Causes of respiratory muscle weakness The respiratory muscles ventilate the lungs with a pump- ing action that is as signi \201 cant as that of the heart. The most important inspiratory muscle is the diaphragm. Contract ion of diaphragm muscle \201 bres leads to down- ward movement of the dome of the diaphra gm with out- ward movement of the lower chest wall. This generates negative intrathoracic p ressure, drawing air down a pres- sure gradient from mouth to alveoli. Exhalation is predom inantly a passive phenomenon: as the inspiratory muscles relax, lung elastic recoil causes air to move out of the lungs. As ventilatory requirements rise during exercise, the accesso ry inspiratory muscles are recruited. The external intercostals muscles assist inspiration by rais- ing the lower ribs up and out, increasing the anterior- posterior diameter of the thoracic cavity. The scalene and sternomastoid muscles raise the upper ribs and the sternum . During active expiration and coughing, the most impor- tant muscles are those of the abdo minal wall. By increas- ing intra-abdominal pressure when they contract, they push up the d iaphragm raising intrathoracic pressure above atmospheric pressure, expelling air from the lungs. The internal intercostals assist active expiration by pulling the ribs down and in, thus decreasing thoracic volume. 12 11 ) a P k ( f 10 o e r u s s e r p 9 e d x o d n o b r a c i 8 i l a i t r a P 7 6 5 4 0 25 50 75 100 125 150 Sniff nasal pressure (% predicted) Fig. 2.5.1 Respiratory muscles. Data obtained from 81 patients with motor neuron disease So urce: Lyall R et al., Brain 2001; 124: 2000 \200\22313. Respiratory failure. Medicine 2004. The Medicine Publishing Company. Approach to the patient History and examination Dyspnoea that is unexplained by other cardi o-respiratory factors, particularly if combined with orthopnoea or dysp- noea when partly s ubmerged in water, should induce suspi- cion of respiratory muscle weakness. However, patie nts with generalized weakness may have limited mobility, so exertional dyspnoea may only ma nifest at a late stage. If respiratory muscle weakness is severe or there is increased work of breathing due to obesity or other thoracic pathol- ogy, symptoms of ventilatory failure may develop: daytime somnolence, poor concentration, morning headaches, peripheral oedema. Evidence of generalized neuromuscular disease, e.g. wast- ing and fasciculation, or featur es characteristic of speci \201 c conditions, e.g. myxoedema, dystrophia myotonica may be present. Inspiratory muscle weakness leads to reduced tidal volume and tachypnoea. Accessor y muscle action may be required to maintain ventilation and may be apparent. Patients with bilateral diaphragm weakness will develop orthopnoea and paradoxical inward movement of the abdominal wall during inspiration as diaphragm strength falls to about 25% of normal. Weak ness of bulbar and expiratory muscles may impair speech, swallowing and cough, predisposing to aspiration and pneumonia. AUTHOR \200\231S TIPS \200 Consider respiratory muscle weakness in unexplained breathlessness. In generalized neuromus cular disease the respiratory muscles are usually affected and ventilatory failure may deve lop insidiously. Why are the respiratory muscles important? Any disease affecting the motor nerves or striat ed muscles can affect the respiratory muscle pump as can any condi- tion requiring increase d effort to ventilate the lungs. There is increasing awareness that respiratory muscle weak ness compounds malnutrition, steroid therapy, heart failure, COPD and delayed weaning from mechanical ventilation in intensive care. Respiratory muscle weakness is often over- looked as a cause of breathlessness or poor cough, despite wide availability of techniques that c an detect respiratory muscle weakness and quantify its severity. Ventilatory assistance can support respiration during acute episodes of respiratory muscle weakness (e.g. polio, Guil lain \200\223Barr syndrome). Patients with chronic respira- tory muscle impairment can be supported with a variety of techniques to assist ventilation (e.g. non-invasive positive p ressure ventilation, negative pressure \200\230iron-lung \200\231 ventilation) It is there fore important for respiratory physicians to initiate and interpret simple tests of respira tory muscle function when appropriate. Lung function The usual lung function abnormality is a restrictive defect with a low VC and reduced TLC. In patients with diaphragm weakness the VC falls when supine. A fall of >25% when moving from standing to supine is considered unequivo- cally abnormal. The demonstrati on of a normal supine VC indicates that a patient does not have clinically signi \201 cant inspiratory muscle weakness. If there is no pre-existing pulmonary condition the diffu- si on coef \201 cient (KCO) will be normal or slightly increased. Because alveolar volume is decreased, carbon monoxide diffusing capacity (TLCO) is also decreased. CHAPTER 2.5 Respiratory muscle function 33 Direct measurement of respiratory muscle strength Mouth pressures Measurement of maximum in spiratory and expiratory pressures (MIP and MEP) generated at the mouth are the most widely used tests of global inspiratory and expiratory muscle strength. The maneuvers required ca n be dif \201 cult for some patients and rely on maximum volitional effort. Normal ranges are available, but there is considerable variability even in healthy subjects. A value at t he lower end of the normal range can be due to mild weakness or a Overnight oximetry with transcutaneous CO2 may be use- ful as demonstration of nocturnal hy poventilation signi \201 es that respiratory muscle weakness is severe enough to lead to v entilatory failure. Imaging A chest radiograph showing small lungs may indicate inspiratory muscle weakness, a raised hemi-diaphragm may be due to a phrenic nerve lesion causing hemi-diaphragm paralysis . Ultrasound or \202 uoroscopic screening may be able to detect paradoxical diaphragm mov ement where there is severe unilateral or bilateral diaphragm weakness. Is unexplained breathlessness due to respiratory muscle weakness? Yes Excludes clinically important inspiratory muscle weakness Normal VC with <20% fall when supine No Yes e d i s d e B MIP >80 (M), >70 (F) No SNIP >70 (M), >60 (F) Yes No Further respiratory and peripheral muscle assessment required. Results suggest respiratory muscle weakness is likely No Yes No treatment required if lungs otherwise normal. Consider hemidiaphragm studies Review clinical picture. Is diaphragm weakness isolated? Yes No y r o t a r o b a L Establish diagnosis if uncertain, consider phrenic nerve conduction studies EMG, muscle bio psy, neurological opinion Regular follow up, SNIP, VC, MEP and Qs MVC at each visit Symptoms of respiratory muscle pump failure Repeat formal studies with sleep study. Consider ventilatory assistance Fig. 2.5.2 Algorithm for the approach to assessment of respiratory muscle function. M MASOLI & P HUGHES 34 sub-maximal effort in a normal subject. Unequivocally nor- mal pressures are useful in excl uding respiratory muscle weakness. catheters into the esophagus and stomach, specific measurements of inspiratory, expiratory and trans- diaphragmatic pressures can be obtained during snif \201 ng and coughing. By co mbining invasive pressure measure- ment with electrical or magnetic phrenic nerve stimulati on, a non-volitional measure of diaphragm strength is available. These tests may detect uni lateral diaphragm weakness or a phrenic nerve lesion, but are rarely available outside spec ialist laboratories. Nasal pressure Sniff nasal inspiratory pressure (SNIP) relies on a manoeu- vre that is easi er to perform than MIP and provides an accurate, easy and non-invasive assessment of global inspir- atory muscle strength. It can be particular helpful when deciding whether to pursu e the \201 nding of a low MIP, but may under-estimate inspiratory strength in COPD where pressure transmission from within the thorax may be delayed. The equipment required for thi s test is becoming more widely available. Conclusion An appreciation of respiratory muscle activity is important in understanding how the lungs are ventilated. A graded approach to testing the respiratory muscles can provide insight into the progress of various disease states and into unexplained respiratory sympt oms. Cough pressures Pressure or peak \202 ow generated during a cough can help determine expi ratory muscle strength. Further reading Polkey M, Green M, Moxham J. Measurement of respiratory muscle Speci \201 c or invasive tests The non-invasive tests rely on rapid pressure transmission from thorax to mouth as well as good patient comprehen- sion, cooperation and motivation to estimate global inspir- atory or expiratory strength. By swallowing pressure strength. Thorax 1995; 50: 1131 \200\2231135. Troosters T, Gosselink R, Decramer M. Respiratory muscle assess- ment. Eur Respir Mon 2005; 31: 57 \200\22371. 35 Chapter 3 Clinical presentations Chapter contents 3.1 Chronic cough 36 3.2 Breathlessness 38 3.3 Haemoptysis 40 3.4 Chest pa in 42 3.5 Pre-operative assessment 44 3.6 Solitary pulmonary nodule 46 3.7 Wheeze 50 3.8 Th e acute admission with a new unilateral pleural effusion 54 3.9 Unexplained respiratory fai lure 56 H FATHI & A MORICE 36 3.1 Chronic cough De \201 nition Cough is an expulsive expiration with a characteristic sound. It is a prote ctive re \202 ex designed to combat aspira- tion and the stimulus to cough may arise anywh ere within the territory of the vagus nerve. When cough persists for over 8 weeks it is arb itrarily de \201 ned as chronic. Pharyngeal lower oesophageal sphincter re \202 ex during swallowing. Pathological: \200 Loss of its natural tone e.g. hiatus hernia. Movements: \200 Gastrointestinal dysmotility: there is a strong correla- tion between oesophageal dysmotili ty, irritable bowel syndrome, and chronic cough. Reverse oesophageal peristalsis also occur s. Diaphragmatic movements: speci \201 cally during phona- tion, typically on the telephon e. Epidemiology Cough is the commonest complaint for which medical attention is sought. Chroni c cough is reported by 12% of the population and is considered to have a signi \201 cant i m- pact by 7%. Women cough more than men. Smoking has a dose-related effect on cough. Other signi \201 cant associa- tions are obesity, regurgitation, and irritable bowel syn- drome . Clinical approach History: key questions and hints in answers pointing to re \202 ux as th e cause \200 Causes In the absence of obvious other chest disease (normal CXR) three common causes of ch ronic cough are said to exist; gastric re \202 ux, asthma syndrome (cough-variant asthma a nd eosinophilic bronchitis), and rhinitis (upper airways cough syndrome in the USA). Howeve r a common typical clinical history, histological and in \202 ammatory pro \201 le point to re \202 ux as the major cause of undiagnosed chronic cough. Atypical causes of chronic cough are as follows: \200 Is the cough worse at night or during the day? During the day. When is the \201 rst cough of the morning ? On rising. What makes you cough? Talking speci \201 cally on the phone o r laughing. How many minutes after a meal does the cough come? Roughly 10 min, sometimes th e swallowing can trigger cough. Does your voice go after a coughing bout? Yes, sometimes. D oes any one else in the family have the cough? 10% yes. Is it related to your posture? Chan ge in position makes it worse; like bending, lying. Do you have any funny taste in your mou th? Metallic taste. Do you produce sputum? Not much, white color spu- tum sometimes. Do you wheeze at all? If yes, wheezing bouts immedi- ately following cough indicates aspiration. \200 Medication (e.g. angiotensin-converting enzyme (ACE) inhibitors) \200\223 relief may be de layed by 18 months follow- ing cessation of treatment. Inhaled foreign body \200\223 parti cularly in toddlers. Tonsillar enlargement \200\223 may be lingular. Auricular pathology \200\223 stimulation of Arnolds \200\231 nerve which is the auricular branch of the vagus n erve. Tic disorders (Tourette \200\231s) \200\223 mainly adolescent boys. \200 \200 Impact of chronic cough The impact of cough on quality of life has been shown to be compara ble to that of severe COPD. A patient with chronic cough suffers numerous physical and psyc hological consequences from their condition: \200 \200 Physical exam General exam (e.g. weight, clubbing) added to the exami- nation of the upper airways as well as listening to the lungs may provide clues to diagnosis. Physical: cough syncope, urinary incontinence. Psychological: social exclusion, marital dis harmony, depression. Risk factors Smoking, sex, obesity, and family history. Pathophysiology Cough re \202 ex sensitivity In almost all forms, upregulation of the vari ous cough re- ceptors (such as the capsaicin receptor (TRPV1)) heightens cough sensitivity and leads to paroxysms of cough. Changes in atmospheric conditions (i.e. either going from a hot to a cold room or vise versa), perfumes, gastro-oesophageal re \202 ux (GOR), and AC E inhibitors are its known triggers. Investigations Baseline evaluation should look for pulmonary and extra- pulmonary condition s which cause cough. A chest radio- graph and lung function tests are mandatory in an early stage. Next steps are recommended as follows: Respiratory investigations \200 \200 Laryngoscopy. Bronchoscopy (when foreign body suspected). Re \202 ux pathophysiology Non-acid re \202 ux as well as acid re \202 ux causes chronic cough, hence the greatest association of regurgitation rather than heart burn with chronic cough. The reasons for re \202 ux are: Lower oesophageal sphincter incompetence: this res ults in irritation of the larynx or perhaps aspiration of gastric con- tents, and is caused by: \200 AUTHOR \200\231S TIP Ventricular obliteration is highly characteristic for GOR. (Fig. 3.1.1 ). Physiological transient opening: \200 To combat aerophagy and occurs 10 min post-prandial or on rising in the morning. CHAPTER 3.1 Chronic cough 37 Full acid suppression: PPI BD+ ranitidine at night for 2months SUCCESS C O A N SUCCESS T Metoclopramide (10mg TDS) 1 month D I B N C U SUCCESS Domperidone (10mg TDS) 1 month E Fig. 3.1.1 Typical re \202 ux variations in laryngoscopy: A. Arythenoid erythema, B. Vocal cord oedema, C. Ventricular obliteration, D. Posterior commisure hypertrophy. Review the symptoms and consider oesophageal studies for fundoplicaication Re \202 ux investigations Most tests for the diagnosis of GOR are only partially help- ful, as pH studies are designe d to detect acid component in GOR. Non-acid re \202 ux can precipitate severe coughing wit h no trace with regard to pH monitoring; pH studies and manometry can be useful in deciding whether fundo- plication should be offered. Other useful investigations are: \200 Trying other medications Surgery (30% chance of failure) C Suppressant agent: morphine (5mg BD up to 10mg BD) 2months O Oesophageal impedance: it detects both acid and non- acid re \202 ux. High resolution oeso phageal manometry. Salivary pepsin (a new pepsin analyzer which will com- mercially be avai lable soon). N \200 SUCCESS Suppressant agent: disofrol (1 tablet BD) T Treatment We aim to either tackle the speci \201 c cause of cough or, if this fails, to su ppress it. The European Respiratory Society (ERS) and British thoracic Society (BTS) guidel ines endorse therapeutic trials. The following ladder for re \202 ux cough is recommended (Fig. 3.1.2). I Baclofen: GABA agonist, (5mg TDS, up to 10mg TDS) 2months SUCCESS N U Further reading Dicpinigaitis P, Tso R, Banuch G. Prevalence of depressive symptoms among p atients with chronic cough. Chest 2006; 130: 1839 \200\2231843. Erythromycin (250mg BD), 1 month or magnesium salts SUCCESS E Ford AC, Forman D, Moayyedi P, Morice AH. Cough in the commu- nity: a cross sectional surve y and the relationship to gastrointes- tinal symptoms. Thorax 2006; 61 (11): 975 \200\22397 9. Fig. 3.1.2 Treatment ladder for re \202 ux cough. Note: disofrol is an anti-histaminic med ication recommended in American College of Chest Physicians (ACCP) guidelines which is an i nhibitor of TRPV1 cough receptor and this explains its ef \201 cacy in cough. W KINNEAR 38 3.2 Breathlessness What is breathlessness? We all know what breathlessness feels like, but de \201 ning it is dif \201 cult. Breathing is something that we are not normally aware of; when it encroach es into our consciousness we call this sensation breathlessness. This term probably covers several different sensory experiences, meaning dif- ferent things to different people in va rious situations. For example, the air hunger you experience after running as fast as you c an is not likely to be the same as the feeling some patients report of not being able to ta ke a deep enough breath in, or indeed the distress experienced by a patient with an exacerb ation of COPD who is struggling to breathe out through obstructed airways. The physiology o f breathlessness is complex and incom- pletely understood. It seems to arise when there is a mis- match between what the brain expects and what it receives in terms of afferent infor mation from the lungs, airways and receptors in the tendons and muscles of the chest wall. Heart \200\223lung transplant patients \200\223 in whom the vagus nerves are cut \200\223e xperience breathlessness, as do those with complete transection of the cervical spinal cord . Breathlessness can be related to changes in blood gas tensions, but often it is not. Psyc hological, emotional and social factors also play a part. of a foreign body and asthma; more gradual onset suggests \201 brotic lung disease, pleur al effusion, anemia or lung cancer. Precipitating factors Breathlessness is usually made worse by exercise, which can be used t o quantify the degree of breathlessness. Medical Research Council dyspnoea scale 0 Breathlessness only on strenuous exercise 1 Short of breath when hurrying or walking up a slight hill 2 Walks slower than contemporaries on the level because of breathlessness, or has to stop for breath when walking at own pace 3 Stops for breath after about 100 m or after a few minutes on the level 4 Too breathless to leave the house, or breathless when dressing or undressing Most patients with breathlessness \200\223 not just those with heart failure \200\223 fee l worse when they lie down (orthop- noea). Occasionally you will see someone who feels bett er when they lie down; this is called platypnoea. Causes of platypnoea (shortness of breath worse in the upright posture) \200 Intra-cardiac shunt: \200 Atrial septal defect* Intra-pulmonary shunt: \200 \200 \200 Other rarities: \200 \200 Causes of breathlessness The list of diseases that can cause breathlessness is very long. I t may be helpful to think of the route an oxygen mol- ecule takes from the inspired air to reach an end organ \200\223 such as the quadriceps muscle. This ensures considering diseas es affecting the following: \200 \200 \200 \200 \200 \200 \200 \200 \200 Arterio-venous malformations. Cirrhosis, with pulmonary spider naevi. Lung disease, predomi nantly affecting the lower lobes. ventilatory pump (central drive and muscles); upper airway; lower airways ; alveoli; pulmon ary vasculature; red blood cells; cardiac output; peripheral circulation; skeletal muscle. Supraglottic tumor. Autonomic failure. Platypnoea may only occur when there is a right-to-left shunt rise in right- sided pressure (for example with a pulmonary embolism), after thoracic surgery, or if the patient develop s a pericardial effusion. Although unusual, breathlessness on wading into water is a charac teristic symptom of bilateral diaphragm paralysis, because the diaphragm is pushed up in to the chest by the pressure of the water. It is important to remember that breathlessness can just be the result of increased oxygen requirement. This might just be obesity, but someone with bad arthritis may com- plain of b reathlessness because of the energy they expend in struggling up stairs, rather than becaus e of any respira- tory or circulatory problem. Associated symptoms Wheeze is the most useful associated symptom in terms of a diagnosis, w hereas the presence of cough doesn \200\231t usually help. Sudden onset or offset palpitati ons can be a useful clue to breathlessness caused by a cardiac dysrhythmia. Tingling in the tips of the \201 ngers or around the mouth sug- gests hyperventilation, usually of dysfu nctional breathing; there are other features which will lead you to make an active diagnosi s of this syndrome, rather than just exclud- ing any other pathology. Other things to ask a bout are smoking, drug therapy, recreational drug use, pets, hobbies and occupational expos ure. AUTHOR \200\231S TIP Think about the possibility of pulmonary embolism every time you see a patient who is breathless. History Speed of onset Although it is important to ask the patient what they mean by \200 \230breathlessness \200\231, you are more likely to \201 nd out the cause by asking how l ong they have had it and in what situations it occurs. Sudden onset is seen in pulmonary em boli, pneumothorax, left ventricular failure, inhalation CHAPTER 3.2 Breathlessness 39 Feature suggestive of dysfunctional breathing \200 \200 \200 \200 \200 \200 \200 \200 AUTHOR \200\231S TIP Patients often hyperventilate transiently when they are having an arte rial blood gas sample taken. You can only con \201 dently diagnose dysfunctional breathing if there is a chronic respiratory alkalosis, with a bicarbonate concen- tration of <20 mmo l/liter. Sensation of inability to in \202 ate lungs fully. Feeling of the need to take deep breath s or sigh. Breathlessness varies with social situation. Breathless when talking but not on exercise. Very variable exercise tolerance. Dizziness. Tingling in the \201 ngers or arou nd the mouth. Symptoms reproduced by taking 20 deep breaths in the clinic. Previous \200 \230somatisation \200\231 disorders. Management Obviously the best treatment for breathlessness is to cure the underlying diseas e. In some instances this is not possi- ble, and the symptom are treated rather than the ca use. Drugs Opiates are the most effective drugs, but benzodiazepines are also helpful. It is bet ter to use short-acting prepara- tions, so that the patient can get more rapid relief when they get breathless. They should be taken orally \200\223 nebu- lised therapy for breathle ssness has proved disappointing, whether it be opiates, local anesthetic or (more recently) furosemide. Clinical examination Particular things to look out for when examining a breath- less patient: \200 An elevated jugular venous pressure alerts indicates the possibility of pulmonary emboli or primary pulmonary hypertension (as well as heart failure, obviously). In-drawing of the lo wer ribcage towards the end of inspi- ration (Hoover \200\231s sign) indicates that the pat ient is chron- ically hyper-in \202 ated from COPD. Paradoxical inspiratory inward motion of the abdomen is seen in bilateral diaphragm paralysis. It is easier to see when the patie nt is lying down, and when they sniff. If the accessory muscles in the neck are contracting when the patient is at rest, think of a more generalized muscle or nerve problem which has affected the diaphragm and the intercostal muscles. Inspiratory squeaks usually mean extri nsic allergic alveo- litis (which is really a bronchiolitis), although sometimes they are h eard in bronchiectasis. Oxygen Oxygen is an expensive and potentially dangerous therapy. It should only be used whe n the patient has been docu- mented to be hypoxic. It is considered in detail in Chapter 6 There are three ways of giving oxygen: \200 Long-term oxygen therapy (LTOT) is used from an oxy- gen concentrator for at least 12 hours per day in patients with chronic lung disease (usually COPD). Ambulatory oxygen therapy (A OT) is used to improve exercise capacity. Ideally patients should have completed a pulmonar y rehabilitation program \201 rst. During a walk test, oxygen saturation should fall by a t least 4% and to below 90% to qualify for AOT assessment. Short burst oxygen therapy (SBOT ) is used for a few min- utes to relieve breathlessness. There is very little evidence to s upport its use, and it is probably greatly overused. An argument can be made for using cyli nders of air as com- parison when assessing patients for SBOT, because of the relief obtain ed simply by blowing gas onto the face. Investigation \200 Full blood count, D-dimer (negative result will help exclude pulmonary emboli), renal, live r and thyroid function. CXR, HRCT (to look for early diffuse parenchymal lung disease if th e transfer factor is low (see below). An ECG and an echocardiogram are useful as exclusion criteria as well as diagnostic tools. Other therapies \200 Physiotherapists can teach patients with dysfunctional breathing to slow and regularize the ir breathing rhythm. Pulmonary rehabilitation is effective in reducing the breathlessness o f COPD and other chronic lung diseases. Non-invasive ventilation will help patients with ne u- romuscular problems who are struggling to maintain adequate ventilation. Many other non- drug therapies have been tried in patients who are breathless, but here is little evidence to support their use. AUTHOR \200\231S TIP In hyperventilation, the ECG can be abnormal with wide- spread T-wave inversion and ST segment depression. Spirometry, lung volumes , carbon monoxide transfer factor. If these are also normal it is useful to proceed to a \200\230respira- tory \200\231 exerc ise test, where gas exchange is measured whilst the patient exercises on a treadmill or cyc le ergometer. A simpler exercise test such as a shuttle or six minute walk may be undertake n \201 rst, just to con \201 rm that exercise capacity is impaired. Check the oxygen sat uration on air, and proceed to arterial blood gas analysis if it is less than 94%. Further reading Jennings AL, Davies AN, Higgins JPT, et al. Opioids for the palliation of b reathlessness in terminal illness. Cochrane Database of Systematic Reviews 2001; 4. The adult clinical component for the home oxygen service in England and Wales.http://www.br it-thoracic.org.uk/ page294.html C DAVIES 40 3.3 Haemoptysis This is a common presentation of respiratory disease de- \201 ned as the expectoration of blood from hemorrhage into the respiratory tract. It can vary from streaks of blood within sputum to massive, life-threatening hemorrhage. All patients with unexplained haemoptysis require further investigation to identify one of the many causes. The ur- gency of investig ation and treatment will depend on the rate of bleeding and source, and the severity of und erlying lung disease. Most patients do not require admission for investigation or managemen t. AUTHOR \200\231S TIP Always examine the mouth and nasal cavities for possi- ble causes of b leeding and consider the possibility of GI hemorrhage. NB In up to 20% patients a source wi ll not be identi \201 ed \200\223 cryptogenic haemoptysis. Investigations Chest radiograph The chest radiograph may be normal or show signs of the lik ely origin of the bleeding, e.g. a mass, consolidation, bronchiectactic changes. Causes of haemoptysis Laboratory investigations \200 \200 \200 Most common causes Bronchiectasis Tuberculosis * Pneumonia especially Streptococ- cal pneumoniae * Bronchial c arcinoma * Pulmonary embolism * FBC and clotting. Group and save/cross match if massive bleeding. ANCA, autoantibodies and anti-GBM antibodies if vas- culitis is suspected. CT scan \200 Other rarer causes Pulmonary infections A CT scan should be performed in most subjects unless the cause is already known (e.g. a pa tient with recurrent bleeding from bronchiectasis or a tumor). CT scanning may show the cau se of bleeding or may direct the clinician to the likely site of bleeding at subse- quent i nvestigations such as bronchoscopy. Patients suspected of bronchiectasis will also require high resolution CT imaging or image reconstruction to identify parenchymal disease. When pu lmonary embolic disease is considered within the differential diagnosis, CT pulmonary angio graphy should be performed. For some diagnoses further diagnostic investigations may be unn ecessary after the CT scan, e.g. bronchiecta- sis, pulmonary embolism, AV malformation, pul monary \201 brosis. Acute bronchitis Lung abscess Aspergilloma or invasive fungal disease Tumors Carcinoid tumo r Endobronchial metastasis, e.g. breast, melanoma, colon Pulmonary parenchymal diseases Pul monary vasculitis/alveolar hemorrhage syndromes Pulmonary \201 brosis Pulmonary vascular disease Severe pulmonary hypertension AV malformation Mitral stenosis (rare nowadays) Conge nital malformation Aortic aneurysm Miscellaneous causes Endometriosis Anticoagulant therapy or coagulopathy, e.g. DIC Iatrogenic, e.g. Swan \200\223Ganz catheter, bronchial biopsy Dr ugs, e.g. cocaine, thrombolytics Bronchoscopy Bronchoscopy and CT scanning should be considered complementary investigations in patients with haemopty- sis. The timing of bronchoscopy has not been shown to affect th e outcome of investigating the cause of haemopty- sis and it is usual for CT scanning to be performed prior to bronchoscopy. AUTHOR \200\231S TIP Bronchoscopy should be considered in patients with massive haemoptysis , to identify possible source of bleeding when CT is normal, and when CT scan has identi \201 ed a likely abnormality responsible for the bleed- ing. Bronchoscopy may help obtain t issue or microbio- logical samples to con \201 rm the diagnosis, e.g. bronchial tumor, TB, parenchymal lung disease (by transbronchial biopsy) and can help locate anatomical origin of bleeding when considering bronchial arterial embolisation Evaluation of a patient with haemoptysis History: key points \200 \200 Identify time course and likely volume of blood. Identify symptoms suggestive of malignancy , infection, bronchiectasis or embolism. Smoking history. Ask about risk factors for aspira tion. Medications including illicit drugs. \200 \200 Other investigations Where the clinical picture indicates an alternative cause for bleeding further investigations may include: \200 Examination: key points \200 \200 \200 The examination may be normal. Look for signs of bronchiectasis or malignancy. In patients with massive haemoptysis, assessment of air- way and circulation are essential (see Investi gations). Echocardiography, e.g. to identify pulmonary hyperten- sion or mitral valve disease. Bronch ial arterial angiography and embolisation (see below). CHAPTER 3.3 Haemoptysis 41 Massive haemoptysis Massive haemoptysis is fortunately rare (about 5% of epi- sodes of haem optysis) and is often de \201 ned as expectora- tion of blood exceeding between 100 \200 \223600 ml in 24 hours. This de \201 nition is rather arbitrary as the outcome will depend on the volume, rate and cause of the bleeding, and the underlying respiratory reserve and ability of the patient and medical staff to maintain a clear airway. Drugs \200 Tranexamic acid is a drug that inhibits \201 brinolysis, is useful to reduce bleeding. Us ual dose is 15 \200\22325 mg/kg 2 \200\2233 times daily oral or 0.5 \200\2231g 3 times dail y IV. Antibiotics \200\223 when infection is a likely trigger (e.g. in bronchiectasis). Ne bulised adrenaline \200\223 5 \200\22310 ml of 1 in 10,000. Bronchoscopy Bronchoscopy is useful in massive haemoptysis. Rigid bron- choscopy may allow a clearer view of the airway but re- quires expertise and anesthesia. In practice most clin icians will have access to \201 breoptic bronchoscopy in the \201 rst in- stance. Gener al anesthesia and intubation may still be re- quired. Bronchoscopy may allow: \200 \200 Commonest causes \200 