Fatal & Near-Fatal Asthma
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Transcript Fatal & Near-Fatal Asthma
Rising to the challenge
Robert Donovan MD FACEP
Medical Director PHI California
Chief of Staff Doctors Medical Center
Asthma in Ancient Times
Maimonides
“No magic cure for asthma”
“Asthma often starts with a
common cold during the rainy
season”
“The air pollution in Cairo may in
part be responsible”
C a i r o
Cairo is here!
Pathophysiology of Asthma
Inflammatory cells in asthma
Mast cells
Eosinophils
Macrophages
Activated T lymphocytes
Autopsy Findings in Fatal Asthma
smooth muscle
wall thickness
inflammation
Severe Asthma
5% to 10% of asthmatics
Pts. are particularly hard to manage
Still poorly understood
Severe Asthma
Severe
Asthmatics
Female gender
Poor management skills
Smoking/drugs/alcohol
Prior severe attacks
Age > 40
Ability to sense & respond
to airway stimulus
Precipitants of Near Fatal Asthma
Air pollution
Viral URIs
Non-compliance
Emotional stress
Weather changes
Heavy allergen exposure
How Near-Fatal Asthma presents
10% Quickly
-
90% S l o w l y …
-
Physical Exam
Dyspneic, scared, and diaphoretic
Sitting upright or tripod, tachycardic and tachypneic,
and using accessory muscles.
Auscultation reveals diffuse wheezing or, worse, no
breath sounds at all.
Measure Peak Flow?
FEV1 usually low, often
can’t be measured
Although it might be
helpful, ill patients won’t
even try
Failure to FEV1 – not
good!
Lab Findings
WBC might be
In allergic patients, the % eosinophils might be
Serum K+ is often low
lactate is common
? high-dose catecholamine therapy
? increased production by respiratory muscles and
decreased clearance due to circulatory failure
? ABG ?
Blood gas might help
Supplemental O2 generally will correct
hypoxia
CO2 might be or
A steadily rising PaCO2 impending
respiratory collapse
Changes in the pH might be the most help
Management
IV, O2, monitoring
Bronchodilators
Corticosteroids
Plan for ICU Admission
Adjunctive and Experimental Therapy
Albuterol
Mainstay Bronchodilator
MDI’s don’t work
Side effects are tolerable
Atrovent (ipratropium)
Atrovent (with high-dose albuterol) may improve
bronchodilation
Dose of 0.5 mg delivered by nebulization q 1 hour
In our ED, routinely added to full-strength Albuterol
nebulizer
Corticosteroids in Near-Fatal Asthma
Essential Treatment
Effects may be within 1-2
hours although a response
may not be apparent for
days
Possible role for inhaled
corticosteroids in addition
Magnesium
Interferes with calcium-mediated smooth muscle
contraction
Decreases acetylcholine release from parasympathetic
nerve endings
Can cause hypotension and loss of
deep tendon reflexes.
2 grams IV over 20 minutes
BiPAP?
Might be worth a trial
Some supporters
If you can get the patient
to keep it on…..
Ketamine Case Presentation
47 yo male: Hx Asthma, Smoker, Depression, COPD
Began with productive cough yellow/green sputum
Treated in ER; released
Returned 1 hour later – much worse
Tripod, tachypneic, 87% sats.
Initial ABG pH 7.42 pCO2 46 PO2 96% (with o2)
Worsened despite treatment; intubated
Got even worse
difficult to ventilate
high peak airway pressures >80 cmH2O
pH 7.04; pCO2 91; pO2 86% on 100% FiO2.
Other Possibilities
Theophylline
Heliox (70% Helium 30% Oxygen)
IV montelukast
IV terbutaline
Cardio-Pulmonary Bypass
What if things worsen?
Intubation
100% O2
Get back-up airways out
Best person does it
Do full RSI
Decompress the stomach
Keep them paralyzed
DON’T put them on a ventilator! (at first)
You take over the initial bagging of the patient
Premature
Ventilator = Death
Normal Lung
Dynamics
Dynamic Hyperinflation
Dynamic Hyperinflation
Barotrauma
Hemodynamic compromise from
intrathoracic pressure
Decreased venous return
Pulmonary vascular resistance
Decreased cardiac output
Ways to identify
Dynamic Hyperinflation
High Peak airway pressure
Presence of Intrinsic positive end-expiratory pressure
(autoPEEP)
High Plateau Pressure
Clinical
If BP and Airway Pressure
Think tension pneumothorax or DHI stacking
Immediately disconnect pt. from vent and slowly bag, or
not at all
If due to DHI, BP should quickly
If no change, needle both sides of the chest – now!
How to Minimize DHI
Do what it takes to ensure enough time to exhale
Ways to increase expiratory phase include:
Increasing the inspiratory flow rate in order to
decrease inspiratory time - good
Decreasing the Tidal Volume. -
better
Decreasing the respiratory rate -
best
Tidal Volume: 1 liter
Resp. Rate : 10
Insp. Flow : 60 Liters/min
Insp/Exp. Ratio = 1:5
Tidal Volume: 1 liter
Resp. Rate : 10
Insp. Flow : 120 Liters/min
Insp/Exp. Ratio = 1:11
Tidal Volume: 1 liter
Resp. Rate : 10
Insp. Flow : 60 Liters/min
Insp/Exp. Ratio = 1:5
Tidal Volume: 1 liter
Resp. Rate : 6
Insp. Flow : 60 Liters/min
Insp/Exp. Ratio = 1:9
Goal - Avoid Hypoxia
Aim for SaO2 >90% - 95%
For the short term– keep the patient sedated and
paralyzed
PEEP is generally not useful
Be aware of theoretical concerns of too much oxygen
promotes free radicals
How I determine a respiratory rate
Use your Stethoscope !!
Don’t be surprised with rates of 6-10 breaths per
minute at first
Start the ventilator at this rate, use stethoscope to
determine increases in rate
Goal – Minimize Volu-trauma
Aim for Tidal Volume 0f 8 to 10 ml/kg.min
Aim for rate of 10 – 12 breaths per minute
Fatal & Near Fatal Asthma
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