ed management of asthma
TRANSCRIPT
DR. A. SAJJAD PATHAN MBBS MHADEPARTMENT OF ACCIDENT & EMERGENCY MEDICINE
KOKILABEN DHIRUBHAI AMBANI HOSPITAL & MEDICAL RESEARCH INSTITUTE, MUMBAI
Bronchial Asthma
Objectives
Review the Diagnosis & ED Management of Bronchial Asthma
Introduction
Reactive airway disease Airway Inflammation Bronchial Hyperresponsiveness/Narrowing Reversible airflow obstruction
Pathophysiology
Reduction in airflow diameter Smooth Muscle contraction Vascular Congestion Bronchial wall edema Thick secretions
Causes
Common Triggers include respiratory infections, environmental allergens, change in weather, and exercise. In some cases it is associated with NSAID/ASA use, beta blocker use, and emotional stressors.
Risk Factors for Death Previous ICU admission/intubation >2 hospitalizations/ >3 ED visits in last year > 2 canisters of SABA usage Poor socio economic status Drug Abusers Other Co morbidities
Symptoms/Exam
Triad of Dyspnea, Wheezing, and Cough. Early in the attack: Chest Tightness Wheezes may be absent at both ends of spectrum As the severity progresses: Wheezing becomes apparent Expiration is prolonged Use of accessory muscles become evident (Diaphragmatic
Fatigue) Silent Chest “No Wheeze” means think about the worst Pulses Paradoxus & Paradoxical Respiration Change in Mental Status
Differential
“All that wheezes is not asthma” CHF Upper Airway Obstruction COPD Aspiration Bronchiectasis
Classification of Severity
Mild Dyspnea with only activity
PEF > 70 % predicted/personal best Moderate Dyspnea interferes with or limits usual
activity
PEF > 40 – 69 % Severe Dyspnea at rest, interferes with
conversation
PEF < 40 % Life Threatening Severe + Perspiration
PEF < 25 %(Source: Tintinalli, 2010)
Diagnosis & Patient Monitoring
Best Initial Test: PEFR Most Accurate Test: FEV1 pre & post Broncho-
dilation (NAEPP Report 3, 2007)
“These tests provide rapid, objective assessment of patients and serves as a guide to the effectiveness of therapy”
(Tintinalli, 2010)
Pulse Oximetry: To assess and monitor oxygen saturation during treatment
Capnography is the non-invasive method of choice for monitoring ventilation
ABG in Asthmatics
ABG is not indicated in most mild to moderate cases. It does not predict clinical outcome and should not supersede clinical findings to determine the need for intubation
Severity pH PCO2 PO2
Mild Increased Decreased Normal
Moderate Normal Normal Normal/Decreased
Severe Decreased Increased Decreased
ABG in Asthmatics
Investigations
Routine CXR is not indicated: Would be normal or would show hyperinflation
Is indicated if there is suspicion of pneumonia, CHF, pneumothorax, or other medical concern
Routine CBC is not indicated: Slight Leucocytosis sec. to β2 agonist or steroid use
Theophylline levels
ECG: May show RV Strain, non specific ST-T abnormalities
Cardiac Monitoring for all elderly and/or cardiac patients
Treatment
The Goal of treatment of acute asthma in ED is “to reverse airflow obstruction”
Use of β2 agonist Adequate oxygenation Relieve inflammation
Treatment
O2 Therapy to keep saturation > 90% Inhaled β2 –agonist Albuterol or levo-albuterol (no specific advantage
proven) Continuous or intermittent By handheld MDIs or nebulizer (drug delivery is
equivalent) Can combine with Ipratropium (Anticholinergics:
Alone is not a first line therapy) Parentral β2 agonist (Epinephrine/Terbutaline S/C) has
no proven advantage over aerosol
Treatment
Systemic Steroids: Oral or IV equally effective Requires 4 hours to show effect so administer early Decreases the need for hospitalization and subsequent
relapses Patients should continue oral therapy for 3 – 10 days Oral burst (40 – 80 mg ) or IV Prednisolone 1-2 mg/kg /
d; IV Methyprednisolone (1 mg/kg qid) No known advantage for higher doses
Treatment
Magnesium Sulfate IV in dose of 1- 2 gms over 30 mins is indicated in acute, very severe asthma with a PEF <25%
Heliox (80% Helium + 20% Oxygen) lowers airway resistance and acts as an adjunct in care of severe cases. (Insufficient data on whether its use can avert intubations, ICU admissions, and improves morbidity/lowers mortality)
Antibiotics are only indicated if underlying bacterial pneumonia is suspected
Treatment (What not to use)
Theophylline: No longer used, infact dangerous with β2 agonists. At levels >30 mg/ml , can cause seizures and arrythmias
Mast Cell Modifiers: Nedocromil or Cromolyn Leukotriene Modifiers: Zafirlukast/ zileuton.
Ventilation
Initiate when there are s/o
acute ventilatory failure NPPV (NIV): The role of its use
in patients with severe asthma is
still uncertain
It may be helpful but not as well
as in CHF and COPD
Do not initiate in patients with
suspected pneumothorax
Mechanical Ventilation
If Progressive hypercarbia and acidosis or mental deterioration, intubate and ventilate.
Inducing Agent: Ketamine is the preffered inducing agent, do not use in elderly and patients with potential for cardiac ischemia
“Mechanical ventilation does not relieve the airflow obstruction – it merely eliminates the work of breathing and enables the patient to rest while the airflow obstruction is resolved”
Mechanical Ventilation
• Goal: Maintenance of adequate oxygenation (>90%) without the concern of normalizing the PCO2
• Achieved through “Controlled mechanical hypoventilation or permissive hypoventilation”
• Reduced frequency (12 or 14/min), low tidal volumes (6 to 8 ml/kg) and prolonged expiratory phase.
• Provide deep sedation: Propofol is useful in such cases but watch for hypotension
• NM blockers may be required but their use is associated with post extubation muscle weakness.
Disposition & Follow Up
Take into account
Subjective Measures: Resolution of wheezing, improvement of air exchange, ptient opinion
Objective Measures: FEV1 or PEFR nomalization
Historical Factors: Compliance, ED visit history, hospitalizations in past (Patients with a history of relapse will have a relapse regardless of management)
Disposition Checklist
Good response: PEF > 70%, No Distress, Normal PE Goes Home:
Inhaled SABA + Oral Steroids (5 – 7 Days) Teach MDI Technique, Emphasize use of spacer or
holding chamber Peak Flow Meter (Teach technique), Keep PEF Diary Arrange Close Follow Up in 1 - 4 weeks (Ideally 1
Week)
Disposition Checklist
Incomplete Response:
PEF 40 – 69%
Admit to Ward: Oxygen, Inhaled SABA, Oral or IV Steroids, Monitor vitals, PEF, SaO2
Poor Response: PEF <40%, Severe symptoms, mental confusion and
agitation, PCO2 > 45 Oxygen, Inhaled SABA, IV Steroids, Adjunct Therapy Intubation and Mechanical ventilation Admit in ICU