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Chapter 3: Obstructive lung disorders 113

Management of acute severe asthma in adults in hospital
IMMEDIATE TREATMENT
Features of acute severe asthma
• Peak expiratory flow (PEF) 33–50% of best
(use % predicted if recent best unknown) • Oxygen 40–60%
• Can't complete sentences in one breath (CO 2 retention is not usually aggravated by oxygen therapy in asthma)
• Respirations ≥25 breaths/min • Salbutamol 5 mg or terbutaline 10 mg via an oxygen-driven nebuliser
• Pulse ≥10 beats/min • Ipratropium bromide 0.5 mg via an oxygen-driven nebuliser
• Prednisolone tablets 40–50 mg or IV hydrocortisone 100 mg or both if very ill
• No sedatives of any kind
Life threatening features
• PEF <33% of best or predicted • Chest radiograph only if pneumothorax or consolidation are suspected or patient requires IPPV
• SpO 2 <92% IF LIFE THREATENING FEATURES ARE PRESENT:
• Silent chest, cyanosis, or feeble respiratory • Discuss with senior clinician and ICU team
effort • Add IV magnesium sulphate 1.2–2 g infusion over 20 minutes
• Bradycardia, dysrhythmia, or hypotension (unless already given)
• Exhaustion, confusion, or coma • Give nebulised β 2 agonist more frequently e.g. salbutamol 5 mg up to every
15–30 minutes or 10 mg continuously hourly
If a patient has any life threatening feature.
measure arterial blood gases. No other investigations are needed
for immediate management.
Blood gas markers of a life threatening attack: SUBSEQUENT MANAGEMENT
• Normal (4.6–6 kpa, 35–45 mm Hg) PaCO 2
• Severe hypoxia; PaO 2 <8 kPa (60mmHg) IF PATIENT IS IMPROVING continue:
irrespective of treatment with oxygen • 40–60% oxygen
• A low pH (or high H + ) • Prednisolone 40–50mg daily or IV hydrocortisone 100 mg 6 hourly
• Nebulised β 2 agonist and ipratropium 4–6 hourly
Caution: Patients with severe or life threatening attacks may not
be distressed and may not have all these abnormalities. The IF PATIENT NOT IMPROVING AFTER 15–30 MINUTES:
presence of any should alert the doctor. • Continue Oxygen and steroids
• Give nebulised β 2 agonist more frequently e.g. salbutamol 5 mg up to
every 15–30 minutes or 10 mg continuously hourly
Near fatal asthma • Continue ipratropium 0.5 mg 4–6 hourly until patient is improving
• Raised PaCO 2 IF PATIENT IS STILL NOT IMPROVING:
• Requiring IPPV with raised inflation pressures
• Discuss patient with senior clinician and ICU team
• IV magnesium sulphate 1.2–2 g over 20 minutes (unless already given)
• Senior clinician may consider use of IV β 2 agonist or IV aminophylline
or progression to IPPV
MONITORING
Peak expiratory flow in normal adults
660 660
650 75 190 650 • Repeat measurement of PEF 15–30 minutes after starting treatment
640 72 183 640
69 175 MEN • Oximetry: maintain SpO 2 >92%
630 630
620 66 167 620 • Repeat blood gas measurements within 2 hours of starting treatment if,
610 63 160 610 - initial PaO 2 <8 kPa (60 mmHg) unless subsequent SpO 2 >92%
Ht. Ht.
600 (ins) (cms) 600 - PaCO 2 normal or raised
590 590
580 580 - patient deteriorates
570 570 • Chart PEF before and after giving β 2 agonists and at least 4 times daily
560 560 throughout hospital stay
550 550 Transfer to ICU accompanied by a doctor prepared to intubate if:
540 STANDARD DEVIATION MEN 48 = litres/min 540 • Deteriorating PEF, worsening or persisting hypoxia, or hypercapnea
530 STANDARD DEVIATION WOMEN 42 = litres/min 530
PEF • Exhaustion, feeble respirations, confusion or drowsiness
520 520
L/min 510 510 • Coma or respiratory arrest
500 500
69 175 WOMEN
490 490
480 66 167 480
470 63 160 470
460 60 152 460 DISCHARGE
450 57 145 450
Ht. Ht.
440 (ins) (cms) 440 When discharged from hospital patients should have:
430 430 • Been on discharge medication for 24 hours
420 IN MEN VALUES OF PEF UP TO 100 LITRES/MIN LESS THAN 420
410 PREDICTED, AND IN WOMEN LESS THAN 85 LITRES/MIN LESS 410 and have had inhaler technique checked and recorded
THAN PREDICTED, ARE WITHIN NORMAL LIMITS.
400 400 • PEF >75% of best or predicted and PEF diurnal variability <25%
390 390 unless discharge is agreed with respiratory physician
380 380 • Treatment with oral and inhaled steroids in addition to bronchodilators
• Own PEF meter and written asthma action plan
15 20 25 30 35 40 45 50 55 60 65 70 • GP follow up arranged within 2 working days
AGE IN YEARS • Follow up appointment in respiratory clinic within 4 weeks
Nunn AJ, Gregg I. New regression equations for predicting
peak expiratory flow in adults. BMJ 1989;298;1068–70. Patients with severe asthma (indicated by need for admission) and adverse
behavioural or psychosocial features are at risk of further severe or fatal attacks
• Determine reason(s) for exacerbation and admission
• Send details of admission, discharge and potential best PEF to GP
Figure 3.6 The BTS/SIGN British guideline on the management of asthma in hospital. Thorax 2003;58(Suppl I). Reproduced with
permission of the British Thoracic Society.