Journal WatchJournal WatchJeffrey P Schaefer, MD

May 8, 2007

Today's ArticleToday's Article

• This article is ‘overwhelming’ !!!

BackgroundBackground• we believe that body organs

respond to emotional state

• asthma patients may experience ‘stress-associated breathlessness’ without increased airway obstruction

• mental state may alter measurements of breathing

ObjectivesObjectives• strained breathing may trigger

breathlessness in asthma patients

• asthma patents will feel more breathless with the same breathing pattern or with a stress induced breathing pattern

MethodsMethods• ‘Study of Harm’

– normals: exposure ? ‘disease’– asthma: exposure ? ‘disease’

• Exposure arithmetic task

• Disease altered breathing• breathlessness

PatientsPatients• Well Children 9-13 years (7)• Children with Asthma 9-14 yr (8)

– stable disease and free of infx x 1 mo– FEV1 > 70% of predicted– continue inhaled corticosteroid– STOP bronchodilator x 24 hr– informed consent

Exposure ‘subtraction’Exposure ‘subtraction’

MeasurementsMeasurements• magnetometer respiration band• electromyography electrodes• Borg breathlessness scale

ResultsResults

Timing of Resp Muscle Timing of Resp Muscle ActivityActivity

• Phase Angle– maximum EMG should occur at

maximum chest expansion

– at baseline:– asthmatic children

• reduce EMG activity earlier in inspiration• tend to have abdominal strain in

inspiration whereas normal have abdominal strain in expiration

• these effects diminish during arithmetic (distracted)

‘‘phase reversal’ with math*phase reversal’ with math*A & B* A & B* chest expansion chest expansion

C & D* C & D* frontal diaphragm EMG frontal diaphragm EMG

• no sig difference this was a ‘wash’

What does What does this all mean?this all mean?

Author’s remarksAuthor’s remarks• asthmatic children tend to ‘control

their breathing’ possibly to reduce turbulent airflow / irritation

• breathing became ‘closer to normal’ during arithmetic

• WHY?– distraction probably not– interaction between CNS and

breathing in the setting of disability?

• Are the results of the study valid?– comparison groups similar except for factor

under consideration?– similar measurements in both groups?– follow-up sufficient?– temporal relationship correct?– dose response gradient?

• What are the results?– association between exposure and outcome?– precision of risk estimate?

• Will the results help me in caring for my patients?– applicable to my practice?– magnitude of the risk?– stop the exposure?