Severe asthma management
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Severe asthma management
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Severe asthma management
- 1. SEVERE ASTHMA M A N 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 reversible bronchoconstriction – 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 • Previous poor 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 • Treated with 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 the night: – 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: • Intravenous infusions – 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 • Mech ventilation 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/work of 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 – Drug of 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 • Reviewed by 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 – Acute Severe 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/
Notas do Editor
- Commonly managed in community – salbutamol MDI/PO steroids Early treatment prevents many hospital presentations/admissions for severe exacerbations.
- H/over to me – initial presentation Q: comment on Severity of his asthma
- Sig morbitity from underestimation of severity of exacerbation Q: What sorts of patients are more likely to have severe/life threatening exacerbations
- 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
- Handed over to myself Examination of evidence behind treatments.
- Cochrane Syst rev 461 pts Beta agonists established mainstay in treatment Continuous vs intermittent 1 in 10 prevented hospital admission
- 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
- Cochraine syst rev 1 in 3 in Severe asthma No benefit in non-severe asthma
- Cochraine syst review Given winthin 1 hour – minimize the delay to onset Q: IN the asthmatic that’s not improved/deteriorating - treatment options?
- 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
- 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.
- 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
- Evidence base not as established as in COPD Difficulties assicuated with mech ventilation increased length of stay, cost, morality Potential benefits of NIV