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Acute respiratory ment. Acute respiratory problems can be non-invasive ventilation (NIV) for considered anatomically, separating into COPD patients with hypercapnic venti- diseases of the airway, parenchyma, latory failure (Table 1).3 NIV helps by medicine pleura and pulmonary vasculature, all of unloading fatigued respiratory muscles, which can be complicated by respiratory keeping collapsed alveoli open, failure. improving ventilation/perfusion (VQ) Melissa Heightman MB BChir MA MRCP, mismatching, reducing intubation, Specialist Registrar in Respiratory Medicine shortening hospital stay and lowering Geoff Bellingan BSc MBBS PhD FRCP, Airways disease mortality. NIV is now available almost Consultant in Respiratory Medicine and universally in UK hospitals, but it still Critical Care Chronic obstructive pulmonary disease cannot be used in nearly half of accident University College Hospital, London (COPD) and can present simi- and emergency or medical assessment larly with and breathlessness units. The need for short-term mechan- Clin Med 2007;7:267–71 but their distinction is important as ical ventilation does not appear to pre- management differs. dict short- or long-term mortality. accounts for a large Suitable patients should be identified 4 part of acute medical presentations. Chronic obstructive pulmonary early. Patients with acute respiratory problems disease Intravenous (iv) is are increasingly cared for on admissions falling from favour following a Cochrane units and can be discharged without res- COPD prevalence is increasing and pro- review demonstrating its failure to piratory physician input. Fortunately, the jected to be the third leading cause of increase FEV1 or shorten hospital admis- British Thoracic Society (BTS) and the death by 2020. The BTS1 and NICE2 sion, while at the same time increasing National Institute for Health and Clinical issued guidelines in 1997 and 2004, adverse effects.5 Pulmonary rehabilitation Excellence (NICE) have produced excel- respectively (Table 1). Significant devel- is underutilised but beneficial, improving lent guidelines to assist in their manage- opments have occurred in the use of exercise capacity and quality of life (QoL).

Table 1. Chronic obstructive pulmonary disease (COPD).1,2 Investigations • CXR, ECG, FBC, U&E • ABG if saturations <92% • theophylline level if on oral theophylline Management • oral prednisolone 30 mg for 7–14 days, then stop • triggers may be non-infective (humidity/pollution/smoke) and 1/3 may be viral. Antibiotics should be used only if increased sputum/change in colour or clinical/CXR evidence of if , ensure control of FiO (aim saturation 90–92%) • 2 • NIV is the treatment of choice for hypercapnic ventilatory failure with acidosis (pH <7.36 >7.25); ensure safe environment and appropriate ceilings of treatment established • doxapram only if NIV is contraindicated or unavailable • assessment of suitability for intubation should include functional status/BMI/use of home oxygen/comorbidity and QoL – not just age and FEV1 Discharge • establish on long-term inhaled therapy, advice re cessation, educate patients and carers • supported discharge by community nurses may be appropriate • assessment for LTOT should occur 6 weeks post-exacerbation (LTOT indicated if pO2 <7.3 on air, or <8 if evidence of pulmonary hypertension/polycythaemia) • vaccination reduces exacerbation frequency • refer to pulmonary rehabilitation programmes if possible NIV • BIPAP used in hypercapnic ventilatory failure in COPD. NIV can also be used if ventilatory failure is due to chest wall deformities or in cases of obesity hypoventilation; specialist input is often helpful here. NOT recommended in asthma as intubation likely • CPAP used in hypoxic due to pulmonary oedema/pneumonia – high risk of failure, so best used in ICU • start promptly once indication confirmed • can use face or nasal masks • ensure appropriate environment/staff training • agree ceiling of therapy on starting treatment/liaise closely with ICU • contraindications include facial burns, haemodynamic instability, copious secretions, altered consciousness, undrained and bowel obstruction

ABG = arterial blood gas; BIPAP = biphasic positive airway pressure; BMI = body mass index; CPAP = continuous positive airway pressure; CXR = chest X-ray;

FBC = full blood count; FEV1 = forced expiratory volume in 1 sec; Fi02 = fractional concentration of O2 in inspired gas; ICU = intensive care unit; LTOT = long- term O2 therapy: NIV = non-invasive ventilation; QoL =quality of life; p02 = partial pressure of O2; U&E = urea and electrolytes.

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Quadriceps myopathy may be a particular beta-agonist . Interest- beta-agonists achieve similar improve- feature of COPD exacerbations, causing ingly, tiotropium has a 24-hour duration ments to short-acting counterparts, anaerobic metabolism at low work rates, of action, dissociating 100 times more although formoterol may be superior.

increasing CO2 retention. slowly from M1 and M3 receptors than Long-term inhaled glucocorticoids are Many COPD patients benefit from ipratropium; it also reduces exacerba- indicated in severe COPD (FEV1 <50% being discharged on anticholinergic and tions and improves QoL. Long-acting predicted or frequent exacerbations).

They may slow decline in FEV1 and reduce exacerbation frequency, but the Table 2. Asthma severity. clinical significance is uncertain. Near fatal asthma Raised pCO or requiring • 2 Life-threatening asthma Asthma Any one of: • PEF <33% best or predicted SpO <92%/cyanosis Acute asthma is common and potentially • 2 normal PaCO (4.6–6.0 kPa) • 2 life-threatening. BTS guidelines were • silent chest published in 19976 (updated 20047 and • feeble respiratory effort 20058). Important considerations are: • bradycardia • • predicting when admission is • exhaustion required • /coma • determining when intensive care unit (ICU) admission is necessary Any one of: • PEF 33–50% best or predicted • respiratory rate >25/min • knowing the most effective • heart rate >110/min treatment delivery, and • inability to complete sentences in one breath • ensuring appropriate discharge Moderate asthma • increasing symptoms and follow-up. exacerbation • PEF >50–75% predicted • no features of acute severe asthma Enquiries into asthma deaths suggest • wide PEF variability (>40% diurnal variation for >50% of that most occur with severe chronic dis- the time over >150 days despite intense treatment) ease. Inadequate inhaled therapy, follow- • sudden severe attacks on background of well controlled up and psychosocial vulnerability often asthma also play a part. Assessing the severity of an attack is multifactorial (Table 2). PaCO = partial pressure of CO in alveolar gas; pCO = partial pressure of CO ; PEF = peak expiratory 2 2 2 2 Treatment is outlined in Table 3 and flow; SpO2 = peripheral oxygen saturation. includes oxygen, beta-agonists and

Table 3. Treatment of asthma exacerbations. • Oxygen to maintain saturation >92% • Nebulisers or MDI with a spacer is equally suitable for mild and moderate asthma • Severe asthmatics benefit from continuous nebulisation (5–10 mg /hour) • Higher doses of salbutamol offer no benefit over standard doses • Anticholinergic agents (usually ipratropium bromide) are beneficial in moderate to severe acute asthma • Evidence for iv beta-agonists is limited; they should be used only if inhaled therapy cannot be used reliably • Early (90 min) (40–50 mg prednisolone or 200 mg hydrocortisone) significantly reduces admission; should be given to all acute asthmatics. No benefit of iv over oral demonstrated. Steroids should be continued for at least 5 days to reduce relapse; tapering dose is unnecessary • Inhaled steroids can be continued whilst on oral treatment; pooled evidence suggests this is beneficial Addition of iv MgSO to beta-agonists and corticosteroids is beneficial in all patients who have not had a good response to inhaled • 4 bronchodilators, with greatest effects in severe asthmatics. Recommended dose 2 g iv over 20 min (up to 10–20 g can be given in ICU over 12 hours with close monitoring of serum Mg++). • No added benefit demonstrated from iv aminophylline • Routine antibiotics not appropriate – most triggering infections will be viral • Insufficient evidence for use of LTRAs or long-acting beta-agonists in acute asthma (currently reserved as add-on therapy in outpatients) • The use of heliox can not be recommended on current evidence

ICU = intensive care unit; iv = intravenous; LTRA = receptor antagonist; MDI = metered dose inhaler; MgSO4 = magnesium sulphate.

268 Clinical Medicine Vol 7 No 3 June 2007 CME Acute Medicine corticosteroids as the mainstay. Addition Key Points of iv MgSO4 to beta-agonists and corticosteroids is beneficial in all Excellent up-to-date British Thoracic Society or National Institute for Health and patients who have not responded well to Clinical Excellence guidelines are available for all common acute respiratory inhaled bronchodilators, particularly problems severe asthmatics.9 Those failing to respond, evidenced by worsening Patient education is vital in asthma, with best outcomes relating to self- hypoxia, hypercapnia, acidosis, exhaus- management programmes, a clear written action plan for the patient and regular medical follow-up tion or drowsiness, require ICU referral. In general NIV is not suitable and should Non-invasive ventilation is beneficial in chronic obstructive pulmonary disease never be given outside ICU. Intubation patients with hypercapnic ventilatory failure; it should be established promptly and mechanical ventilation are often dif- CURB-65 criteria are useful indicators of severity, outcome and for referral to ficult and should be performed by an critical care experienced intensivist. Discharge should occur when stable KEY WORDS: asthma, chronic obstructive pulmonary disease, community-acquired on inhaled therapy, ideally with peak pneumonia, non-invasive ventilation, , pneumothorax, pulmonary expiratory flow rate above 75% predicted embolus with less than 20% diurnal variability. An acute admission is a good opportunity to optimise long-term treatment, especially Table 4. Community-acquired pneumonia (CAP). as many of those admitted have the poorest disease control and a social situ- CAP and CURB-65 1 point for each of: confusion (MMT 7 mmol/l compliance: 15% reattend within two • RR >30 bpm weeks. Guidelines stress asthma educa- • BP systolic <90 mmHg or diastolic <60mmHg tion; self-management programmes, • age >65 written action plans and regular medical Score 0 or 1: may not require admission Score 2: consider inpatient care follow-up have evidence supporting their Score ≥3: manage as severe pneumonia efficacy. CAP Investigations • CXR, FBC, U&Es (from BTS 2004 guidelines) • Severe: – blood and sputum cultures – legionella/pneumococcal antigens Parenchymal disease – paired serological tests Non-severe: The most common parenchymal acute • – blood and sputum cultures (pre-antibiotics if respiratory disease is community- possible) acquired pneumonia (CAP). Patients • consider mycobacterium TB if history/CXR suggestive with interstitial lung disease can present • consider underlying malignancy – follow-up CXR if acutely with superadded infections, exac- smoker/slow response to treatment erbations of underlying disease or occa- If poor response to treatment consider alternative diagnosis (PE//bronchial sionally with new presentations such as /foreign body/COP/pulmonary eosinophilia) or unusual pathogen cryptogenic organising pneumonia or Antibiotic guidelines for CAP: • Hospitalised patients with 7 days oral amoxicillin plus macrolide or fluoroquinolone pulmonary haemorrhage. Such patients non-severe pneumonia with enhanced pneumococcal activity (levofloxacin or should be urgently referred to respiratory moxifloxacin) physicians. • Severe pneumonia 10 days iv co-amoxiclav, cefuroxime or cefotaxime plus iv macrolide/or iv levofloxacin plus iv benzylpenicillin (eg if penicillin or local concern regarding Community-acquired pneumonia Clostridium difficile diarrhoea with beta-lactam use) The BTS produced guidelines for CAP in Antibiotic treatment should be rationalised according to positive microbiology and iv treatment changed to oral as soon as clinically appropriate and the temperature has been 10 11 2001 (updated 2004). An important normal for 24 hours part of management is identifying those who are likely to need admission to ICU. BP = ; bpm = breaths per minute; BTS = British Thoracic Society; CAP = community- acquired pneumonia; COP = cryptogenic organising pneumonia; iv = intravenous; CXR = chest X-ray; FBC The CURB-65 score (Table 4) is well = full blood count; MMT = Mini-Mental Test; PE = pulmonary ; RR = respiratory rate; TB = established for assessing severity and pre- tuberculosis; U&Es = urea and electrolytes. dicting prognosis. Investigations and CURB = Confusion: new mental confusion defined as an Abbreviated Mental Test score ≤8; Urea: raised antibiotics are reviewed in Table 4. >7 mmol/l; Respiratory rate: raised ≥30/min; Blood pressure: low BP (systolic <90 mmHg and/or diastolic ≤60 mmHg). Hypoxaemic patients who are resistant to

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high-flow oxygen may benefit from con- an exudate or transudate. Accurate his- embolism (PE) and malignancy should tinuous positive airway pressure (CPAP). tory and examination are essential, and a be reconsidered and a watch and wait They commonly proceed to intubation, diagnostic tap performed unless the effu- policy adopted. so CPAP should ideally only be used in sions are bilateral and the clinical setting ICU. Caution with high-flow oxygen is strongly suggestive of a transudate. necessary in COPD patients with hyper- Drainage is urgently required only if Spontaneous pneumothoraces capnia, especially if the respiratory rate is an is diagnosed (frank pus, already low. Gram stain, or pleural pH <7.2). Other- Non-trauma related spontaneous pneu- Patients should not be discharged if wise it is usually best to establish the mothoraces are either primary (in they have a fever above 37.8°C, heart rate cause prior to drainage, although a ther- absence of lung disease) or secondary above 100/min, respiratory rate below apeutic tap can be performed to relieve (underlying lung disease), but most 24/min, systolic blood pressure (BP) symptoms if necessary. Tuberculous effu- patients with presumed primary pneu- below 90, oxygen saturations below 90%, sions typically resolve with tuberculosis mothoraces have subpleural bullae at inability to maintain oral intake or (TB) treatment without requiring thoracoscopy, commonly smoking abnormal mental status. These features drainage. Cytology is positive in 40–87% related. The BTS guidelines (2003) have 13 are all associated with a high readmission of malignant effusions and should always a limited evidence base. An inspiratory rate and mortality. All patients should be be repeated if negative. Blind pleural CXR is adequate initial imaging, reviewed six weeks after discharge. In biopsy slightly increases diagnostic yield although CT of the thorax may be smokers, those over 50 or those with above cytology but has a much higher required to differentiate pneumothorax persistent symptoms, a follow-up chest yield when looking for TB, although from complex bullous lung disease, when X-ray (CXR) to check for resolution pleural adenosine deaminase may super- aberrant tube position is suspected or should be arranged, with bronchoscopy sede this. Parapneumonic effusions are surgical emphysema obscures the CXR. considered for persisting changes or common, occurring in 20–40% of symptoms such as haemoptysis. patients hospitalised with pneumonia. In Primary pneumothoraces an undiagnosed exudative effusion (25% of cases) a thoracoscopic biopsy is the No intervention is necessary in primary gold standard. Computed tomography pneumothorax if the rim of air is less than (CT) can be useful to look for paren- 2 cm and the patient is not breathless. For Pleural effusions chymal, mediastinal or pleural disease to larger pneumothoraces, aspiration and The BTS released guidelines for pleural direct biopsy, particularly in those repeat CXR should be tried initially and fluid analysis in 2003 (Table 5).12 The key unsuitable for thoracoscopy. If no clear hospitalisation may be unnecessary. If this is to distinguish whether the effusion is diagnosis is established, TB, pulmonary fails, it can be repeated or an intercostal tube inserted, to be removed 24 hours after full re-expansion/cessation of air leak. Small 10–14F tubes are adequate Table 5. Pleural fluid analysis. except for large leaks. For leaks persisting for more than 48 hours referral to the • Note colour – if milky, check TG/ to look for respiratory team for high volume, low – if bloodstained, suggestive of malignancy, PE or benign asbestos effusions pressure suction is mandatory. Referral – check haematocrit (if >50% peripheral blood, suggests haemothorax) may be made to thoracic surgeons for – pus: empyema and drainage required surgical . • Send for protein/LDH/glucose/Gram stain/AFB/culture (in sterile tube and blood culture bottles)/cytology (20 ml adequate)/pH if parapneumonic effusion suspected • Exudate if protein >30 g/dl Secondary pneumothoraces • Light’s criteria useful if protein 25–35 g/dl (likely exudate if LDH >2/3 upper normal Persistent leaks are common with sec- serum level or pleural to serum LDH >0.6, pleural to serum protein >0.5. If still equivocal, if the difference between pleural and serum protein levels is >3.1 g/dl, a ondary pneumothoraces and the lung transudate is likely) may be harder to expand – hence guide- • Differential cell counts sometimes useful: >50% pleural lymphocytosis common in lines suggest admission and aspiration of malignancy, TB and post-CABG; presence of suggests an acute process even small pneumothoraces. Patients • Pleural fluid ADA/TB PCR can be useful if tuberculous effusion suspected with larger pneumothoraces, aged over • Request pleural amylase level if pancreatitis or oesophageal rupture is suspected. A 50 or who are breathless should proceed pleural:serum amylase >1.0 indicates a raised level directly to drainage. Administration of oxygen can speed up spontaneous reab- AFB = acid fast bacilli; ADA = adenosine deaminase; CABG = coronary bypass grafting; sorption of air by four times above base- LDH = low-density ; PCR = polymerase chain reaction; PE = pulmonary embolus; TB = tuberculosis; TG = . line (approximately 1.25% of volume of hemithorax per day).

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Table 6. Diagnosis of pulmonary embolus (PE). obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Pulmonary embolus (GOLD) Workshop summary. Am J Respir Crit Care Excluded by: • Normal D-dimer level and low clinical probability (for some assays Med 2001;163:1256–76. an intermediate clinical probability) 5 Barr RG, Rowe BH, Camargo CA. Normal perfusion scan • Methylxanthines for exacerbations of Normal multislice CTPA • chronic obstructive pulmonary disease. Confirmed by: • Positive CTPA Review. Cochrane Database Syst Rev • High probability VQ scan and high clinical likelihood 2003;(2):CD002168. • Evidence of acute DVT with non-diagnostic CTPA/VQ scan 6 British Thoracic Society et al. The British DVT is found in 70% of patients who present with PE; 50% of patients with proximal DVT guidelines on asthma management. Thorax develop a PE. Therefore, if DVT is suspected on clinical grounds, a positive leg ultrasound is 1997;52(Suppl 1):51. often sufficient to confirm venous thromboembolism (if normal, a follow-up scan should be 7 The BTS/SIGN British guidelines on the arranged to confirm) management of asthma. April 2004 update. Thorax 2003;58(Suppl I). CTPA = computed tomographic pulmonary angiography; DVT = deep ; PE = pulmonary 8 The BTS/SIGN British guideline on the embolism; VQ = ventilation/perfusion. management of asthma. The BTS/SIGN guideline on asthma management. November 2005 update. www.brit-thoracic. org.uk/Guidelinessince%201997_asthma_ html-38k- A 50 mg bolus of alteplase via a periph- 9 Rowe BH, Bretzlaff JA, Bourdon C, Bota eral vein is recommended. The value GW, Camargo CA Jr. Intravenous Diagnosis of PE is important but notori- of thrombolysis is otherwise not clear. magnesium sulfate treatment for acute ously difficult. The BTS issued guidelines Generally LMWH is preferable to unfrac- asthma in the emergency department: a in 2003.14 The clinical presentation is tionated heparin, having equal efficacy systematic review of the literature. Ann Emerg Med 2000;36:181–90. varied and often non-specific. Further and safety while easier to use. Oral anti- 10 Guidelines for the management of investigation is essential but hampered coagulation should be started once PE is community acquired pneumonia in adults. by the imperfect sensitivity of diagnostic confirmed; it should be given for three Thorax 2001;56(Suppl IV). techniques. Initial standardised assess- months for a first idiopathic PE but for 11 British Thoracic Society. Guidelines for the ment of clinical probability is funda- at least six months otherwise. Recent management of community acquired pneumonia in adults 2004 update. London: mental and determines subsequent evidence suggests D-dimers are useful to BTS, 2004. www.brit-thoracic.org. 15 investigations and the interpretation of determine duration of therapy. Testing uk/c2/uploads/MACAPrevisedApr04.pdf results. Assessment involves considera- for thrombophilia should be performed 12 Maskell NA, Butland RJ; Pleural Diseases tion of major risk factors, presentation in patients over 50 years, with recurrent Group, Standards of Care Committee, (sudden dyspnoea, tachypnoea or chest PE or a strong family history. Investiga- British Thoracic Society. BTS guidelines for pain in the absence of another explana- tion for occult malignancy should be the investigation of a unilateral pleural effusion in adults. Thorax 2003; tion) and basic investigations (ECG and triggered only if CXR/routine blood tests 58(Suppl 2):ii8–17. CXR). A negative D-dimer test is a useful are abnormal or if suspected from the 13 British Thoracic Society guidelines for negative predictor if coupled with effec- history. the management of spontaneous tive pretest probability scoring; however, pneumothorax. Thorax 2003; different D-dimer tests have different 58(Suppl 2):ii39–52. References 14 British Thoracic Society guidelines for the performances (Table 6). management of suspected acute pulmonary Low molecular weight heparin 1 British Thoracic Society guidelines for the embolism. The British Thoracic Society (LMWH) should be given before imag- management of chronic obstructive Standards of Care Committee, Pulmonary ing when clinical probability is inter- pulmonary disease. The COPD Guidelines Embolism Guideline Development Group. Group of the Standards of Care Committee mediate or high; imaging should be Thorax 2003;48:470–84. of the BTS. Thorax 1997;52(Suppl 5): 15 Palareti G, Cosmi B, Legnani C et al; performed within 24 hours of presenta- S1–28. PROLONG Investigators. D-dimer testing tion or within one hour if massive PE is 2 National Institute for Clinical Excellence. to determine the duration of anti- suspected. CT pulmonary angiography is Chronic obstructive pulmonary disease. coagulation therapy. N Engl J Med 2006; the imaging modality of choice. Isotope London: NICE, 2004. www.nice.org.uk/ 355:1780–9. pdf/CG012_niceguideline.pdf scanning should be considered only if 3 Ram FS, Lightowler J, Wedzicha JA. Non- CXR is normal and there is no cardiopul- invasive positive pressure ventilation for monary disease. A non-diagnostic result treatment of respiratory failure due to should always be followed by further exacerbations of chronic obstructive imaging. pulmonary disease. Cochrane Database Syst Rev 2003;(1):CD004104. Thrombolysis is first line treatment for 4 Pauwels RA, Buist AS, Calverly PM et al. massive PE and can be instituted on clin- Global strategy for the diagnosis, ical grounds if cardiac arrest is imminent. management, and prevention of chronic

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