STATUS ASTHMATICUS Sigrid Hahn, MD Andy Jagoda, MD, FACEP Department of Emergency Medicine Mount Sinai School of Medicine New York, New York

Status Asthmaticus: A Case Study  35 year old male with a week of progressive difficulty breathing  Using albuterol inhaler every hour, ran out several days prior to presentation  Multiple hospitalizations with two intubations  PMH: none  Meds: albuterol inhaler  Smokes “a few cigarettes” per day

Status Asthmaticus: A Case Study  BP 150/90, P 120, RR 28; pulse oximetry 92%  Alert, speaking in clipped sentences; sitting upright and appearing very anxious  Lungs: severe inspiratory and expiratory wheezing, minimal air movement  Heart: tachycardic  CXR hyperinflation, no pneumothorax

Indicators of Severe Asthma  Anxious & diaphoretic appearance, upright position  Breathlessness at rest and inability to speak in full sentences  PaCO 2 normal or increased  PEFR < 150 L/min or <50% predicted  Pulse oximetry < 91% on room air  Tachycardia (HR>120) and tachypnea (RR>30) Expert Panel Report 2: Guidelines for the diagnosis and management of asthma. National Institute of Health- National Heart, Lung and Blood Institute 1997; NIH publication number

Approach to Severe Asthma  Reverse bronchoconstriction  Treat airway inflammation  Correct hypoxemia  Consider differential diagnosis  Monitor for complications  Pneumothorax  Hypotension

In the management of a severe asthma exacerbation…  How should beta-agonists be administered?  Do anti-cholinergics have a role?  Does aminophylline have a role?  Does magnesium have a role?  Should heliox be used?  Does ketamine have a role?  Should non-invasive ventilation be used?  What should the ventilator settings be if the patient is intubated?

How should beta-agonists be administered?   Inhaled  -agonists are the treatment of choice   In a small trial, there was no significant difference in response to delivery by nebulization, MDIs with spacers, or inhaled powder Raimondi AC et al. Chest 1997 Jul; 112:24-28  The optimal dose of inhaled  -agonists varies among patients; dose should be titrated to effect  Continuous treatments have been shown to be safe in patients with underlying cardiac disease Olshaker et al. Am J Emerg Med 1993;11:131 Olshaker et al. Am J Emerg Med 1993;11:131

If the patient is unable to tolerate inhaled  -agonists …  SC  -agonists are an alternative to inhaled  -agonists  A randomized trial compared SC epinephrine mg with SC terbutaline mg  Patients years old  Similar increases in PEFR and FEV at 5 and 15 minutes  No difference in heart rate or blood pressure  Continuous ECG revealed no dysrhythmias Spiteri: Subcutaneous adrenaline versus terbutaline in the treatment of acute severe asthma. Thorax 1988; 43:19-23

Should IV  -agonist therapy be used?   Meta-analysis evaluated 9 RCTs comparing IV  - agonists in addition to, or instead of, inhaled  -agonists in severe asthma in adults   No significant differences were found in multiple outcome measures between the two groups   If the patient can tolerate inhaled  -agonists, there is no evidence to support the use of IV  -agonists Travers et al. The Cochrane Library, Issue 3,   Small trial found a benefit of IV  -agonists in children Browne et al. Lancet 1997; 349:

All patients with a severe asthma exacerbation should receive steroids  60 – 125 mg IV methylprednisolone  mg PO prednisone

Should anticholinergics be used in addition to  -agonists?   Multiple doses of inhaled ipratropium bromide in addition to  -agonists lead to a significant improvement in pulmonary function tests   Benefits most pronounced in those with FEV 1<30% Rodrigo. The Role of Anticholinergics in Acute Asthma Treatment- An Evidence-Based evaluation. Chest 2002;

Is there a role for IV aminophylline?  Multiple theoretically beneficial effects  Cochrane review included 15 trials and found no benefit over  -agonists alone in PFTs or admission rates, even in severe asthma  Increase in adverse effects (palpitations, vomiting) Parameswaran et al. The Cochrane Library, Issue 3, 2003  No studies compare outcome in patients with severe asthma who are unable to tolerate inhaled  -agonists  There is no evidence supporting its use

Is there a role for IV magnesium?  Smooth muscle relaxation (bronchodilation)   2 gm of MgSO4 is safe and beneficial in patients with severe acute asthma exacerbations (FEV1<25% predicted) Rowe. Magnesium sulfate for treating exacerbations of acute asthma in the emergency room (Cochrane Review) The Cochrane Library. Issue 3, 2003.

What is heliox?  Helium/Oxygen mixture  Laminar flow reduces the resistance associated turbulent airflow in more proximal airways  Allows greater oxygen delivery during inspiration  Reduced work of breathing

Should heliox be used in severe asthma?  Review found no improvement in PFTs regardless of heliox mixture or severity of disease  Heliox-driven nebulizers were associated with a non-significant improvement in PFTs at one hour Rodrigo. Chest 2003; 123: Rodrigo. The Cochrane Library. Issue 3, 2003

Does IV ketamine improve outcome?  Ketamine is a bronchodilator, potentiates catecholamines  44 consecutive patients with severe asthma attacks received IV ketamine (0.1 mg/kg bolus and 0.5 mg/kg/hour infusion) for 3 hours  Ketamine was used in conjunction with other standard therapies  No difference in PEFR or hospital admission Howton. Randomized, double-blind, placebo-controlled trial of IV ketamine in acute asthma. Annals of Emergency Medicine. 27(2)

Does noninvasive ventilation improve outcome?   BiPAP can reduce work of breathing, reduce bronchoconstriction and offset intrinsic PEEP   Small trial used BiPAP in 30 patients with severe asthma after one neb in the ED   Excluded patients with hypotension, Osat < 90%, depressed mental status, need for emergent intubation   BiPAP was interrupted for short periods to deliver nebulized albuterol   Significant improvement in PFTs Soroksky et al. A Pilot Prospective, RCT of BiPAP in Acute Asthma Attack. Chest :

Who should be intubated?  Decision should be based on clinical deterioration (altered mental status, respiratory fatigue)  Neither hypoxia nor hypercarbia are absolute indications for intubation

Rapid Sequence Intubation in the Asthmatic  Oxygenate  Premedicate  Lidocaine  Glycopyrollate or atropine  Induction with ketamine  Paralysis with succinylcholine  Intubation with large ETT

Mechanical Ventilation in Asthma  Volume cycled ventilation  FiO  Rate 8-10  I:E 1:4 or 1:5  V T 5-7 cc/kg  PEEP 0  Maintain peak pressures < 45 cm H 2 0, plateau pressure < 30 cm H20

If peak pressures remain > 45 mm Hg…  Evaluate for pneumothorax  Ensure sedation & paralysis  Allow hypercapnea (up to 80 mmHg)  Consider pressure-controlled ventilation

Complications of Mechanical Ventilation  Hypotension  Barotrauma

CONCLUSIONS  Beta-agonists are first line therapy  Aminophylline does not have a role in the management of acute asthma  Anticholinergics and magnesium may improve PFTs in severe asthma  Consider using noninvasive ventilation  Intubation is based on clinical status, not on numbers  Ventilator management is based on permissive hypercapnea