Use of High Frequency Chest Compression in Pediatric Status Asthmaticus

Background: Asthma is the third largest cause of hospitalization in children under 15 years of age. It is a reversible obstructive lung disease caused by airway inflammation and constriction of the airway smooth muscle. Mucus producing glands of the airway become enlarged resulting in overproduction of mucus. All those factors result in airflow obstruction with airtrapping, ventilation/perfusion mismatch and hypoxia. Therapies such as beta-agonists (i.e. albuterol), anti-cholinergics (i.e. atrovent) and steroids are used for an acute asthma attack. Unfortunately, patients may develop status asthmaticus, in which a severe attack does not respond to nebulized bronchodilators, and require intensive care admission.

HFCC is an FDA (1988 under Class II 510K) approved device/modality of chest physiotherapy which has been utilized in patients with mucus hypersecretion, atelectasis and pneumonia. There is a paucity of pediatric studies. A comparative retrospective/prospective data analysis on exacerbations and hospitalizations in medically fragile (profoundly disabled) children using outpatient HFCC showed that use of this therapy reduced days of hospitalization for pulmonary exacerbations. Long term use in quadriplegic children reduced pulmonary secretions, incidence of pneumonia, and number of hospitalizations. In the pediatric cystic fibrosis population, there was improvement of lung function during hospitalization and long term decrease in progression of lung disease. Furthermore, in patients with mild to moderate asthma, there was no decline in lung function with the use of beta agonist and HFCC versus beta agonist alone indicating good tolerance and safety.

Because asthma patients have mucus hypersecretion and this modality has been shown to be effective in other patient populations with mucus hypersecretion, this modality can be used as a means of reducing pulmonary morbidity and thereby allowing the respiratory therapist to allocate his/her time more efficiently.

Purpose:

Assess efficacy of HFCC in PICU population ages 2 to 21 years of age with status asthmaticus

Design: Prospective Randomized non blinded HFCC (administered 4 times a day for 20 minutes) with conventional PICU management of asthma exacerbation vs. conventional PICU management of asthma exacerbation alone. Child would not have any of the standard asthma medications changed or stopped because of this study.

End Points of Interest:

Primary

1) PICU days - Average number of PICU days as researched is about 4.47 days. There may be factors such as non PICU floor availability and PICU rounds that may delay transfer from PICU to the non PICU floor. So the official discharge from PICU will be when the attending PICU physician announces or deems it acceptable for PICU discharge

Secondary

1. Length of hospitalization

2. Pediatric Asthma Severity Score a validated asthma severity score in pediatric population: 1) observed level of respiratory distress 2) accessory muscle use 3) auscultation (degree of wheezing) 4) oxygen saturation 5) respiratory rate Scored observations 0, 1, or 2 and total the observation numbers for a Severity score

3. Discomfort

Patient inclusion 2 to 21 yo (VEST approved for over two yo) Admitted to PICU for status asthmaticus Negative urine pregnancy test prior to initiation of study in those with menses

Patient Exclusion

Absolute contraindication to VEST use:

1. Unstable head or neck injury

2. Active hemorrhage with hemodynamic instability

3. Intracranial pressure > 20 mmHg or those in whom intracranial pressures should be avoided (was a relative contraindication but after discussion moved to absolute)

Presence of anomalies such as:

1. Former premature infant with BPD

2. Congenital bronchogenic or pulmonary anomaly (i.e. CF)

3. Congenital heart disease