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  1. Status Asthmaticus Rich Kaplan MD, MS, FACEP

  2. Case #1 • 18 y.o. old BM • 1-2 word dyspnea • Severe distress • No history of intubation • Denies drugs

  3. Case #1 • PHx • Asthma • Allergies • Meds • Advair • Singulair • Albuterol inhaler • Duonebs • Uses less than once a week

  4. Case #1 • HR ~ 140’s • RR 40’s • BP stable • No room air sat • He is above 90% on nebs

  5. Case #1 • Severe dyspnea • May need to be intubated • Protecting his airway • Looks tired • Marked accessory use • Not much air movement

  6. Case #1 • Your exam should take seconds • You cannot access anything from sunrise • What do you do now?

  7. Case #1Immediate Treatment • Albuterol • Atrovent • Solumedrol • Terbutaline • MgSO4

  8. Case #1 • Still with severe distress • 2 word dyspnea • Looks tired • Intubation equipment at bedside

  9. Case #1More Treatment • BIPAP • Heliox ( 70:30) • Epinephrine Drip • 1mg Epi/ 250cc bag ( 4 mcg/cc) • Consider starting at 4 mcg/min

  10. Case #1 • He seems to be doing better with: • BIPAP • Heliox • Epi drip • Still has impressive inspiratory and expiratory wheezes • Limited lung expansion after about 15 minutes

  11. Case #1 • It is ICU time • Now we need an ABG • CO2 is 50.8 • ICU attending will only accept the patient if he is intubated • He will not accept BIPAP • BIPAP discontinued • ED attending tells ICU attending that ABG will be repeated after 30 minutes on Face mask • Epi drip is increased to 8mcg/min • HR is less than 100 • RR in the 20’s

  12. Case #1 • Meanwhile: How does the patient look??? • Still has impressive inspiratory and expiratory wheezes • Increased lung expansion • Speaking about 5+ words at a time • “Playing” with his cell phone • Family is present in the room

  13. Case #1 • Patient instructed to try to take deep breaths • His respiratory rate is now about 16 • He is on Face mask with heliox ( 70:30) • Epi drip has been increased to 8 mcg/min • Patient is told that if he breathes better and if his repeat ABG is improved, that he will not require intubation

  14. Case #1 • Repeat CO2 in about 30 minutes is 33 • Patient has improved markedly • Patient is now Denied admission to ICU

  15. Case Summary • Multiple scenarios with similar presentation and outcome • Avoided intubation • Status asthmaticus • 1-2 word dyspnea • Multiple breathing treatments • Terbutaline • Heliox • BIPAP • IV Epi

  16. Status Asthmaticus • Treatment • Albuterol • Atrovent • Steroid • Terbutaline • Epinephrine • Heliox • BIPAP • Intubation • Ketamine • Inhalational anesthetics • Extracorporeal life support

  17. Status Asthmaticus • Severe bronchospasm that does not respond to aggressive therapies within 30-60 minutes • Severe asthmatic attack with one or more of the following: • Dyspnea (precluding speech), accessory muscle use, RR 35/min • Hr > 140/min • Peak expiratory flow < 100 l/min • I do not measure Peak flows • Hypercapnea ( >= 50 mmHg)

  18. Acute Severe Asthma • Critical limitation of expiratory flow • Increased airway resistance • Premature airway closure • Lung and chest wall dynamic hyperinflation • High intrinsic PEEP • Respiratory muscle fatigue

  19. Near-Fatal Asthma • Respiratory arrest or respiratory failure (PCO2 > 50 mmHg)

  20. Fatal Asthma • Slow-onset • Gradual deterioration of asthma symptoms over several days • Usually associated with chronic poorly controlled asthma • Eosinophilic predominance and mucus in submucosa • Rapid-onset • Symptom onset and progression to life-threatening status within 3 hours • “Greater” hypercapnea • Neutrophilic predominance in airway submucosa

  21. The Four Compartments o o

  22. Respiratory Mechanics • The lung is not homogenous during acute severe asthma • Driving force for expiratory flow is decreased • Persistent activation of inspiratory muscles during expiration--- • Abnormal low pulmonary elastic recoil • High outward recoil of chest wall • Resistance to airflow strongly increased

  23. Respiratory Mechanics • Markedly prolonged expiration • Inspiration starts before static equilibrium is reached • Positive End-Expiratory alveolar Pressure • Auto-PEEP (intrinsic PEEP, PEEPi)

  24. Dynamic Hyperinflation • Incomplete alveolar emptying at the end of expiration • Intrinsic PEEP • Measure end-expiratory flow or • End-expiratory pressure • Increased ventilatory requirement • Prolonged expiratory time • Increased inspiratory threshold load

  25. Dynamic Hyperinflation • Shortening of: • Diaphragm • Inspiratory intercostals • Accessory muscles • Decreased mechanical efficiency • Increased risk of fatigue • With increased obstruction: • CO2 production > Elimination by alveolar ventilation • CO2 increases

  26. Dynamic Hyperinflation • Mean pleural pressure becomes more negative • Interstitial pressures are also lowered • Vascular pressure is maintained • The result: • Interstitial edema and further increase in airway resistance

  27. PEEP • PEEPi in asthmatics • Adding PEEPe may help negative expiratory pressure gradient between alveoli and airway • Asthmatics are less responsive to this intervention • PEEP adds to auto-PEEP in asthmatics • If PEEPe>PEEPi • May worsen dynamic hyperinflation Peigang Curr Opin Crit Care 2002;8(1):70-6.

  28. Time to move on from Dynamic Hyperinflation

  29. Asthmatic Patients • Who do we worry about? • Previously intubated • Noncompliant or poorly controlled • Psychosocial or emotional problems • Frequent flyers • Environmental triggers

  30. What do we look for on exam? • Severe respiratory distress • Accessory muscle use • May be hypoxemic • Tachypneic • Tachycardic • Diaphoretic • Anxious • 1-2 word dyspnea

  31. What do we do? • Rapid assessment • Manage the airway • Aggressive treatment • Respiratory therapist at bedside • Have all the needed equipment at the bedside • Intubation… • Team approach • 2 IVs

  32. Treatment • Albuterol neb • Atrovent neb • Solumedrol 125 mg IV • Terbutaline • 0.25 mg SQ • Epinephrine • 0.3 mg SQ or IM • Magnesium sulfate

  33. Nebulized Treatments • Albuterol • Atrovent

  34. Terbutaline • 0.25 mg SQ Q 20 minutes for 3 doses

  35. EPISQ vs IM • 0.2-0.5 cc Q 20-30 minutes for 3 doses • 1:1000 Epi

  36. MgSO4 • Possible inhibition of calcium influx into airway smooth muscle • Inhibits cholinergic neuromuscular transmission • Stabilization of mast cells and T lymphocytes • Stimulation of nitric oxide and prostacyclin

  37. MgSO4 • 5 intubated asthmatics • 10-20 grams /60 minutes • Decreased peak airway pressure • 3X increased Mg level with hypotension • Vasopressors in 2 patients Sydow, Intensive Care Med 1993;19:467-71

  38. Other Scenarios

  39. Pregnancy • Epinephrine • Concern re: alpha effect and vasoconstriction in uteroplacental circulation • Avoid during pregnancy except in anaphylaxis • Terbutaline • Preterm labor • High dose steroids in animal studies: • ??? cleft palate • Palatal closure usually by 12th week • Albuterol, Atrovent safe

  40. PedsAcute severe asthma • Albuterol • 0.15mg/kg/hr • Albuterol continuous: • 20 mg/hr if > 20 kg • Atrovent • 0.5 mg/dose if > 20 kg or > 6y.o. • MgSO4 • 25-75 mg/kg IV • Terbutaline • 10 mcg/kg IV over 10 minutes • Infusion of 0.1-10 mcg/kg/min

  41. Heliox • Usually 70% Helium: 30% oxygen • Inert gas • 3X reduction in density compared to air • Reduces resistance in airways with nonlaminar flow • Upper and Proximal • Reduces respiratory muscle work • May improve gas exchange • May increase the mass of albuterol delivered • Allows smaller particles to better penetrate the lung periphery • May use with: • Face mask • BIPAP • Mechanical ventilation

  42. Heliox • Work of breathing • Respiratory system compliance • Static property determined by elastic recoil of lung and chest wall • Airway resistance • Dynamic property • Density and viscosity of inspired gas • Airway caliber and configuration • Flow rate McGarvey and Pollack Heliox in Airway Management, Emerg Med Clin N Am 2008

  43. Heliox • Decreased resistance to turbulent gas flow • in the absence of anatomic change • Higher flow rates for same driving pressure • May alleviate dynamic hyperinflation • Heliox seems to decrease the Reynolds number (Re) and facilitate laminar flow in patients with high airway resistance • Improved ventilation • Decreased work of breathing • Decreases the applied force required to achieve a given flow rate

  44. Heliox • 12 adults in ED with severe asthma • 7 face mask, 5 ventilated • PCO2 >45 • 3-5 doses of nebulized albuterol • Significant decrease in PCO2 • (57.9-47.5) • mean of 49 minutes after heliox • pH increased from 7.23-7.32 • Improved ventilation in patients with acute severe asthma Kass Chest 1995;107:757-60

  45. Heliox ( severe asthma) • 3/7 with heliox via FM had symptoms > 96 hours • 2- intubated • 4/7 with symptoms < 24 hours – not intubated • Conditions of all patients were sufficiently improved after 24 hours for heliox to be discontinued Kass 1995

  46. Heliox • Therapeutic bridge for 6-12 hour interval from patient arrival in ED • Failure of asthmatics to respond to heliox via mask may indicate increased risk for intubation Kass 1995

  47. Heliox • 23 adults with acute severe asthma • Randomized controlled trial • 20 minutes of heliox • Significant increase in PEFR ( 58% vs 10%) • Significant decrease in dyspnea scores and RR • Maintenance of improvement over 8 hours Kass Chest 1999;116:296-300

  48. Heliox • Retrospective chart review of 22 ICU patients with status asthmaticus • Intubated • Significant drop in A-a gradient of heliox group • Allowed weaning of FiO2 Schaeffer Crit Care Med 1999;27:2666-70.

  49. Heliox (Peds) • 18 pediatric patients with status asthmaticus • Continuously inhaled nebulized B2 agonist • Solumedrol • Heliox (80:20) vs room air at 10LPM by NRB • Heliox • Increased peak flow • Lessened the dyspnea score • 3 were not intubated (as planned) Kudukis J Pediatr 1997;130:217-24

  50. Heliox (Peds) • Retrospective review • 28 ventilated patients • Significant decrease in mean peak inspiratory pressures • 40.5-35.3 • Mean PCO2 decreased significantly • 58.2-50.5 Abd-Allah Ped Crit Care Med 2003;4:353-7.