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Severe asthma management
This document discusses the management and ventilation strategies for severe asthma. It describes a case of a 28 year old male presenting with severe asthma exacerbation. Key points include: administering bronchodilators, steroids and magnesium to rapidly reverse bronchoconstriction; considering non-invasive ventilation to reduce workload and improve oxygenation; intubating and using ketamine for induction if exhaustion or respiratory failure occurs; and aiming for long expiratory times and minimal pressures if mechanical ventilation is needed to avoid further lung damage. The case study shows how these treatments were applied and the patient was discharged after intensive care.
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Severe asthma management
- 1. SEVERE ASTHMA M AN A G E M E N T A N D V E N T I L AT I O N S T R AT E G I E S
- 2. ASTHMA Characteristics – Episodic reversiblebronchoconstriction – Airway inflammation – Increased mucus production Consequences – Increased WOB • Increased airway resistance/Reduced Compliance – Type 2 Resp failure – Hypercapnia & Hypoxia • Impaired gas exchange • V/Q mismatches
- 3. CASE MB • 28/M •Hx Asthma – Dx 2011 1 Prior hospital admission 1 yr ago – overnight • Flixotide preventer, takes PRN Ventolin prior to exercise • Office job, smoker • BIBA: • Unwell 1 week – cough/sputum /SOB/wheezy Has been self treating with Ventolin • Spoke in words, accessory muscle use, diaphoretic, not confused • RR 30, Sats 88RA, widespread wheeze
- 4. ASTHMA SEVERITY • Severe –Unable to speak sentances – Visible breathlessness/Increased WOB – O2 sats 90-94% • Life threatening – Altered mental state/Drowsy/Collapsed – Poor Resp Effort/Exhausted/Quiet chest – Cyanotic/O2 sats <90%
- 5. RISK FACTORS • Previouspoor control of asthma – Frequent ED/hospital presentations – Previous severe exacerbations / ICU & Intubation etc. • Treatment received prior to presentation – Frequency of Ventolin use – Poor compliance with asthma medications /action plans • Other factors: – Smoking/Illicit drug use, psychosocial problems – Comorbidities - cardiovascular or chronic lung disease
- 6. INITIAL TREATMENT • Aims: –Rapidly reverse bronchoconstriction – Correct severe hypercapnia/hypoxemia • Titrated Oxygen – Sats 92-95% • Continuous Inhaled Salbutamol – Nebulizer/MDI • Ipatropium • Magnesium • Steroids – within 1 hour
- 7. CASE MB • Treatedwith 3 Ventolin nebs/ipratropium/hydrocort/magnesium • Initial gases pH 7.15, Normal CO2, bicarb 20, Lac 2.4 • CXR clear • Initial concerns may require ICU admission • However clinically improved with treatment • Reviewed by ICU – planned for HDU
- 12. CASE MB Through thenight: – Drowsy/Tiring – Increased WOB – Gases relatively unchanged. • Contacted HDU&ICU – Busy with another code • Given cont Ventolin nebs with limited effect • Started on NIV
- 13. ADDITIONAL TREATMENTS Bronchodilators: • Intravenousinfusions – Beta agonists • Salbutamol • Adrenaline – Ketamine • Inhalational Anaesthetic agents – ICU only • Helium/oxygens • Methylxanthines – theophylline/aminophylline – No longer recommended as adjunct in acute asthma WOB/Resp failure: – NIV – Intubation/ventilation Clinical indications: – Falling RR – Drowsiness – Exhaustion – Worsening resp failure
- 14. MECH VENTILATION • Mechventilation in asthma is difficult – Relatively normal alveolar compliance – High airway resistance high airway pressures – Prolonged expiration Risk gas trapping – Gas trapping increases intrinsic PEEP – Very high peak airway pressures – Plateau/insp pause pressures Flow X Resistance Vol/Complianc e + PEEP Alveoli Bronchioles
- 15. MECH VENTILATION Ventilation aims: •Adequate oxygenation • Long expiration times • Avoid breath stacking / volutrauma • Slower RR, higher I:E ratios • Avoid large TV • Manage/Minimize high airway pressures • PEEP zero • Monitor plateau pressures • Consider Permissive Hypercapnia – Minimize barotrauma to lungs – Avoid significant acidosis
- 16. NIV ADV: • Reduce Fatigue/workof breathing • Improve oxygenation/ventilation – V/Q mismatch – Gas exchange – Recruitment – Prevention athelectasis DIS: • Increased risk of barotrauma • May lead to delayed intubation/associated complications • General NIV issues Uses: • To avoid intubation • For preoxygenation/ventilatory support prior to Intubation – Ketamine DSI
- 17. INDUCTION • Ketamine – Drugof choice – bronchodilator • Consider DSI – Optimizing patient with Ketamine/NIV prior to intubation • Prone to hypotension post intubation – caution with propofol etc. – Breath stacking – Hypovolemia – Induction drugs – Tension PTX
- 18. CASE MB • Reviewedby ICU – Trial of Ketamine and Adrenaline infusions in ED as temporising measure • Taken up to ICU – Intubated - Ketamine/NIV prior • Spent 2 nights intubated and further 5 days on the ward • Discharged home with Preventer (increased dose) • Seen further 5 weeks later on a night shift for another exacerbation of asthma…
- 19. RESOURCES/REFERENCES • LITFL – AcuteSevere Asthma http://lifeinthefastlane.com/ccc/acute-severe-asthma/ – NIV & Asthma http://lifeinthefastlane.com/ccc/non-invasive-ventilation-niv-and-asthma/ • Australian Asthma Handbook https://www.asthmahandbook.org.au/ • EMRAP – C3 Asthma Summary Aug 2016 – S Swadron, M Herbert • TheNNT: Quick Summaries of Evidence Based Medicine http://www.thennt.com/ • Ventilator settings in asthma – James Rippey http://scghed.com/2015/11/updated- suggested-initial-ventilator-settings-112015/
Editor's Notes
- #3 Commonly managed in community – salbutamol MDI/PO steroids Early treatment prevents many hospital presentations/admissions for severe exacerbations.
- #4 H/over to me – initial presentation Q: comment on Severity of his asthma
- #5 Sig morbitity from underestimation of severity of exacerbation Q: What sorts of patients are more likely to have severe/life threatening exacerbations
- #7 MDI proven to be equivalent to Neb in those that can use it appropriately. Neb less efficient - has Larger particle and more drug lost However acute illness may prevent use of MDI Advantage of MDI – less labour intensive/inexpensive Reasessment after initial treatment Examination of evidence
- #8 Handed over to myself Examination of evidence behind treatments.
- #9 Cochrane Syst rev 461 pts Beta agonists established mainstay in treatment Continuous vs intermittent 1 in 10 prevented hospital admission
- #10 7 RCTS – hetrogenous studies Anticholinergics less effective than beta agonists Studies compared ipratropium vs placebo as an addition to beta agonists Possibly 1 in 11 prevented hospitalization However inexpensive with good safety profile
- #11 Cochraine syst rev 1 in 3 in Severe asthma No benefit in non-severe asthma
- #12 Cochraine syst review Given winthin 1 hour – minimize the delay to onset Q: IN the asthmatic that’s not improved/deteriorating - treatment options?
- #13 Considering ?IV Ventolin/Adrenaline/ketamine No central access Had never used drugs for this indication before Needed advice Felt that patient will likely need intubation
- #14 Intravenous vs Inhaled beta agonists Inhalational tend to have lower rate of adverse effects – tachycardia/arrhythmias/myocardial injury Case reports of effectiveness of ketamine in status asthmaticus Inhalational agents – limited by expense/need for equipment and staff, Heliox - ?lower density thought to reduce airway resistance – conflicting evidence 2012 cochraine review on aminophylline – no significant additional bronchodilation over beta agonists alone Increased adverse effects – GIT/arrhythmias Addition of intravenous aminophylline to inhaled beta(2)-agonists in adults with acute asthma. Nair P, Milan SJ, Rowe BH Cochrane Database Syst Rev. 2012;12:CD002742.
- #15 Discuss normal airway – normal function, volumes and pressures – upper limits for barotrauma Barotrauma results from high pressure in alveoli not larger airways Peak airway pressure correlates poorly with alveolar pressure Inspiratory pause/plateau pressures
- #17 Evidence base not as established as in COPD Difficulties assicuated with mech ventilation increased length of stay, cost, morality Potential benefits of NIV