Transcript Document 7207058

Asthma and COPD in the
Emergency Department
Sa’ad Lahri
Registrar
Department of Emergency Medicine
UCT / Stellenbosch University
Synopsis
• Focus on ED management with emphasis
that Emergency Medicine is a :
“Prevention, Resuscitation, Stabilization
and appropriate disposition”1 specialty.
1. The Emergency Medicine Consultation : revisited : letter to the editor
South African Family Practice 2006 – Sa’ad Lahri
What is Asthma?
• Chronic inflammatory disorder of airways
• Inflammation causes airway hyper responsiveness often associated with
symptoms (wheeze, cough, SOB).
• Obstruction is reversible
What is the Pathophysiology of
Asthma?
• Pathological changes found in asthma are the 3 “S”s:
• 1. Spasm of smooth muscle hypertrophy which
contracts during an attack
• 2. Swelling or oedema of bronchial mucosa
• 3. Secretions from hypertrophy of mucus glands
leading to thick & tenacious mucus
• All the above cause bronchial narrowing
What is an Asthma Exacerbation?
• Episodes of progressive increase in
shortness of breath, cough, wheezing, or
chest tightness, or some combination of
these symptoms.2
2. Global Strategy for Asthma Management and Prevention
www.ginaasthma.org
Cont… What is an Asthma Exacerbation?
• Represent an exaggerated lower airway response to an
environmental stimulus.
• Respiratory viral infection - main trigger of severe
exacerbations of asthma.
• Airway inflammation is a key pathogenic feature
Which aspects of asthmatics history are
important to current exacerbation?
Other Q’s3
• Prior hospitilizations
• ICU admissions
• Recent ED visits
• Current meds
• Co-morbid conditions
3. Emergency Medicine Secrets 4th Edition
How to assess Asthma severity?
Due to be updated 2007
Indicators of Severe Asthma: Clinically
• Anxious & diaphoretic appearance
• Breathlessness at rest; inability to speak in full
sentences
• PaCO2 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 97-4051
Key objectives of management
• Aim:
- To relieve airflow obstruction and
hypoxaemia
- To prevent relapses
• Repetitive administration of rapidly acting
bronchodilators.
• Early systemic corticosteroids.
• Oxygen
• Complications - (pneumothorax)
Global Strategy for Asthma Management and Prevention
www.ginaasthma.org
Oxygen Assessment Tests
• Pulse oximetry - in all severe asthmatic
patients.
• Arterial desaturation and hypercarbia occur
concurrently and normally only develop in
life-threatening asthma.
• As result, pulse oximetry is a suitable means
for routine assessment of ventilatory status.
Blood Gas?
• Analysis of arterial blood gases can be selectively
reserved:
• oxygen saturations on room air of < 92%
• do not respond to initial treatment, with the FEV1 remaining 30%.
In interpretation of arterial blood gases, attention focuses
• primarily on PaCO2 with normal value in breathless asthmatic being
a warning sign of impending hypoventilation.
• values above 6 kPa (45 mm Hg) indicating a life threatening attack
and probable need for transfer to a high dependency unit (HDU) or
intensive care unit (ICU).
CXR, Bloods and other investigations?
•
Chest radiograph is not routinely needed, being reserved for:
1. those who do not respond to initial treatment
2. or in whom alternative diagnosis such as
pneumothorax or pneumonia is suspected.
•
The serum potassium concentration should be measured, particularly in
patients with prior corticosteroid or diuretic treatment.
•
Hypokalaemia caused primarily by high dose b-agonist therapy is not
uncommon in severe asthma and may require potassium supplementation.
•
Microbiological investigations are seldom required, although purulent
sputum should be cultured if present.
Inhaled bronchodilators
• Inhaled b-agonists are the mainstay of bronchodilator therapy
• Metered dose inhalers with a spacer produce outcomes that are at
least equivalent to nebuliser therapy in severe asthma
• These finding includes those with life-threatening asthma, with an
FEV1 <30% predicted on presentation.
• As a guide, 400 mg salbutamol via a spacer can be considered
equivalent to a 2.5 mg dose of salbutamol via nebuliser. (no spacers
ever seen in Casualty!)
• The addition of ipratropium bromide to inhaled b-agonist therapy
provides an increase in the bronchodilator response in severe
asthma.
• One important indication for the use of anticholinergic
bronchodilators is as first-line treatment for b-blocker induced
attacks.
Systemic corticosteroids:
•
The major issue is the optimal dose and route of administration.
•
There is no benefit in using very high intravenous doses in severe
asthmatics needing hospital admission.
•
In terms of lower doses, the most informative double-blind randomised
study has shown that intravenous hydrocortisone 50 mg four times a day for
two days, followed by prednisone 20 mg daily, is as effective in resolving
acute severe asthma as either hydrocortisone 200 mg or 500 mg four times
daily followed by prednisone 40 or 60 mg daily, respectively.
Prednisone is commonly given po in doses of 40-60mg
Side effects of short term steroid use include rise in glucose, fluid retention,
decrease in potassium, peptic ulcers.
•
•
Route of administration
•
Oral glucocorticosteroids are usually as effective as those administered
intravenously and are preferred because this route of delivery is less
invasive and less expensive.
•
If vomiting has occurred shortly after administration of oral
glucocorticosteroids, then an equivalent dose should be re-administered
intravenously.
•
In patients discharged from the emergency department, intramuscular
administration may be helpful , especially if there are concerns about
compliance with oral therapy.
•
Oral glucocorticosteroids require at least 4 hours to produce clinical
improvement.
Global Strategy for Asthma Management and Prevention
www.ginaasthma.org
What about inhaled steroids?
•
Potential benefits of reduced side-effects, direct airway delivery and greater
efficacy in reducing airway reactivity and oedema.
•
Inhaled glucocorticosteroids are effective as part of therapy for asthma
exacerbations. (VERY EXPENSIVE)
•
In the studies below , the combination of high-dose inhaled
glucocorticosteroids and salbutamol in acute asthma provided greater
bronchodilation than salbutamol alone (Evidence B), and conferred greater
benefit than the addition of systemic glucocorticosteroids across all
parameters, including hospitalizations, especially for patients with more
severe attacks
Is there a role for IV aminophylline?
• Has been used for hundred’s of years
• Cochrane review included 15 trials and found no
benefit over b-agonists, in admission rates, even in
severe asthma
• Narrow therapeutic window with may significant side
effects.
• 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 b-agonists
• There is no evidence supporting its use
Magnesium Sulphate
•
•
•
•
•
Intravenous magnesium now recommended in patients with life-threatening
attacks. Not recommended for routine use in asthma exacerbations
Its use leads to an improvement in lung function and a reduction in hospital
admissions in those who respond poorly to initial treatment, but not those
with less severe asthma responding to initial treatment.
Currently, the evidence relates to a single dose (2 g MgSO4 diluted in 50 ml
0.9% normal saline administered over 30 min) and the efficacy of a
continuous infusion or repeated dose has yet to be determined.
If an intravenous bronchodilator is to be administered, current evidence
favours the use of intravenous magnesium rather than intravenous bagonist or aminophylline.
Nebulized salbutamol administered in isotonic magnesium sulfate provides
greater benefit than if it is delivered in normal saline (Evidence A)
contentious !!!
Should IV b2-agonist therapy be used?
• Meta-analysis evaluated 9 RCTs comparing IV b2agonists in addition to, or instead of, inhaled b2agonists in severe asthma in adults
• No significant differences were found in multiple
outcome measures between the two groups
• If the patient can tolerate inhaled b-agonists, there
is no evidence to support the use of IV b2-agonists
Travers et al. 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). 1996.
What about Adrenalin?
• Non selective Beta agonist that requires (IV/sub cut)
admin.
• Effective bronchial smooth muscle dilator with rapid
onset of action.
• Use for very severe and life threatening asthma.
• “If you hesitate to give epinephrine to a severely
distressed asthmatic, you should consider the fact that if
the patient deteriorates further and suffers
cardiorespiratory arrest the first drug you will administer
is epinephrine 1mg IV”
• ACLS for experienced providers AHA 2003
Does Pregnancy change the management of
acute asthma?
• NO!
•
•
Treat Aggressively
Prevent Maternal Hypoxia
•
Fetal Morbidity/Mortality
• “Risks from respiratory failure and severe acute
asthma are greater than from therapy with
standard medications”
Emergency Medicine Secrets 4th Edition
Non-invasive positive pressure
ventilation (NIPPV)
• Well established role in the management of
exacerbations of COAD, its role in the management of
severe asthma is less clearly defined.
• May be useful in patients with hypercapnic respiratory
failure as long as they are protecting their own airways
• NIPPV can reduce the work of breathing and respiratory
muscle fatigue, thus buying time for transfer to ICU.
• There is concern that it may delay intubation in
deteriorating patients.
DO not use NIPV in
Asthma
How can I tell if my patient is improving?
• Ask them how they feel
• Re-examine
• Obtain objective measurements
(FEV/PEFR)
Who should be intubated?
•
Endotracheal intubation is not curative, is associated with
significant morbidity, and can increase the degree of airway
narrowing and inflammation. Only a very small percentage of
patients presenting to the ED with acute severe asthma will
require endotracheal intubation and assisted ventilation.
•
With the exception of apnoea, or coma no other indications for
intubation.
•
Exhaustion, hypoxaemia and depression of mental status
strongly argue for intubation
•
( if they are distressed and tiring – intubate as with all other
patients)
Rapid Sequence Intubation in
the Asthmatic
•
Oxygenate
•
Premedicate ( disagreement – intubate like any other
propofol/etomidate etc)
– Lidocaine
(2mg/kg) reduce bronchospasm induced by larngoscopy
– Induction with ketamine (preferred agent)
•
Paralysis with succinylcholine
•
Intubation with large ETT(larger tube less airway resistance)
How should I decide if my patient
can be discharged?
• Hospitalise
Patients with a pre-treatment
FEV1 or PEF < 25% percent
predicted or personal best, or
those with a post-treatment
FEV1 or PEF < 40% percent
predicted or personal best,
usually require hospitalization.
• Discharge
• Patients with post-treatment
lung function of 40-60%
predicted may be discharged,
provided that adequate followup is available in the
community and compliance is
assured.
• Patients with post-treatment
lung function ≥ 60 % predicted
can be discharged.
Global Strategy for Asthma Management and Prevention
www.ginaasthma.org
For patients discharged from the
emergency department:
• At a minimum, a 7-day course of oral glucocorticosteroids for adults
• The bronchodilator can be used on an as-needed basis, based on
both symptomatic and objective improvement, until the patient
returns to his or her pre exacerbation use of rapid-acting inhaled 2agonists.
• Use of peak flow meter to monitor therapy at home should be
reviewed.
• Patients discharged from the emergency department with a peak
flow meter and action plan have a better response than patients
discharged without these resources
Global Strategy for Asthma Management and Prevention
www.ginaasthma.org
Antibiotics?
• Purulent sputum may not indicate infection, and
is usually a result of eosinophils in respiratory
secretions
• Antibiotics should not be routinely prescribed as
bacterial infections seldom provoke
exacerbations (in contrast to viral respiratory
tract infections), and their routine prescription
does not influence outcome in exacerbations of
asthma.
Key points
•
•
•
•
Reverse airway obstruction
Reduce the likelihood of recurrence
Relieve significant hypoxaemia
Check for objective measurement of
improvement
• Adequate discharge includes education,
Medications and follow –up.