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