December 6, 2012 December 6, 2012 Adult Bronchoprovocation Tests Adult Bronchoprovocation Tests Lanny J. Rosenwasser, M.D. Dee Lyons/Missouri Endowed Chair in Immunology Research Professor of Pediatrics Allergy-Immunology Division Childrens Mercy Hospital Kansas City, Missouri Professor of Pediatrics, Medicine and Basic Science University of Missouri Kansas City School of Medicine
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December 6, 2012 December 6, 2012 Adult Bronchoprovocation TestsAdult Bronchoprovocation Tests
Lanny J. Rosenwasser, M.D.Dee Lyons/Missouri Endowed Chair in Immunology Research
Professor of Pediatrics Allergy-Immunology Division
Childrens Mercy Hospital Kansas City, Missouri
Professor of Pediatrics, Medicine and Basic ScienceUniversity of Missouri Kansas City School of Medicine
Working Definition of AsthmaWorking Definition of Asthma
Asthma is a disorder of the airways with theAsthma is a disorder of the airways with thefollowing pathophysiological characteristicsfollowing pathophysiological characteristics
• Hyperresponsiveness to a variety of “triggers”Hyperresponsiveness to a variety of “triggers”
““Twitchy” AirwaysTwitchy” Airways
Bronchial hyperresponsiveness is:Bronchial hyperresponsiveness is:
• An abnormal increase in airflow limitation followingAn abnormal increase in airflow limitation followingexposure to a stimulus;exposure to a stimulus;
• Alternatively, a threshold response (e.g., Alternatively, a threshold response (e.g., 20% fall20% fallin FEV1) which occurs at a lower point (dose) in FEV1) which occurs at a lower point (dose) than in a healthy individual.than in a healthy individual.
Types of StimuliTypes of Stimuli
• Direct StimulusDirect Stimulus Cause airflow limitation by a direct actionCause airflow limitation by a direct action on effector cells (e.g., airway smooth muscleon effector cells (e.g., airway smooth muscle cells, mucus producing cells).cells, mucus producing cells).
• Indirect StimulusIndirect StimulusCause airflow limitation by an action of cellsCause airflow limitation by an action of cellsother than effector cells, which then interact other than effector cells, which then interact with the effector cells.with the effector cells.
What do most people use to What do most people use to evaluate airway hyperreactivity?evaluate airway hyperreactivity?
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Scott GC, Braun SR. Scott GC, Braun SR. Chest 1991;100:322-328.Chest 1991;100:322-328.
• Questionnaire to prominent and active Questionnaire to prominent and active investigators using bronchial provocationinvestigators using bronchial provocationtechniques.techniques.
MethacholineMethacholine• Most widely usedMost widely used• Well standardizedWell standardized• Easy to obtain todayEasy to obtain today• Better differentiates reactive/nonreactive airwaysBetter differentiates reactive/nonreactive airways
HistamineHistamine• Good correlation with methacholineGood correlation with methacholine• More side effectsMore side effects• Development of tachyphylaxisDevelopment of tachyphylaxis
• Releases histamine & other mediators fromReleases histamine & other mediators frommast cellsmast cells
• Action is blocked by antihistaminesAction is blocked by antihistamines
• May reflect extent of airway inflammationMay reflect extent of airway inflammationbetter than methacholinebetter than methacholine
AdenosineAdenosine
• Inhalation of aerosolInhalation of aerosol
• Diluent usually 0.9% salineDiluent usually 0.9% saline
• Dosing scheme range 0.04 to 320 mg/mLDosing scheme range 0.04 to 320 mg/mL
• Quadrupling doses reported to be safeQuadrupling doses reported to be safeand efficient - and efficient - DeMeer et al., Thorax 2001;56:362-365DeMeer et al., Thorax 2001;56:362-365
MannitolMannitol
• Indirect stimulantIndirect stimulant
• Dry powderDry powder
• Osmotic stimulant Osmotic stimulant ( osmolarity of airway surface liquid)( osmolarity of airway surface liquid)
• Special dry-powder inhalers neededSpecial dry-powder inhalers needed
• Procedure not well standardizedProcedure not well standardized
• Reports are mainly from AustraliaReports are mainly from Australia
Oral ChallengesOral Challenges
• Performed when proof of sensitivity neededPerformed when proof of sensitivity needed
• Common agents and prevalenceCommon agents and prevalence• Metabisulfite: 5 – 10% in adultsMetabisulfite: 5 – 10% in adults• Tartrazine: <5%Tartrazine: <5%• ASA: 4 to 20%ASA: 4 to 20%
• Time for reaction variesTime for reaction varies
Occupational ChallengesOccupational Challenges
• Specific challenges considered the goldSpecific challenges considered the goldstandard for dx of occupational asthmastandard for dx of occupational asthma
• Change in FEVChange in FEV11 is the primary outcome measure is the primary outcome measure
• Spirometry should meet ATS guidelines for acceptabilitySpirometry should meet ATS guidelines for acceptability
• The quality of the spirogram should be examined after The quality of the spirogram should be examined after each maneuvereach maneuver
• Full FVC efforts lasting Full FVC efforts lasting >> 6 sec should be performed at 6 sec should be performed at baseline and after diluentbaseline and after diluent
• If the FEVIf the FEV11 is the only outcome measure, the expiratory is the only outcome measure, the expiratory
maneuver can be shortened to about 2 sec at other maneuver can be shortened to about 2 sec at other stagesstages
• If shortened maneuver is used, assure If shortened maneuver is used, assure inspiration is completeinspiration is complete
Calculation of Percent ChangeCalculation of Percent Change
The exact concentration that causes a specific fall in a PFT parameter:
PC20FEV1
Concentration that causes a 20% fall in FEV1
PC40SGaw
Concentration that causes a 40% fall in specific conductance
Quality ControlQuality Control
• Nebulizer outputNebulizer output• Verify output initially & after every 20 uses, until anVerify output initially & after every 20 uses, until an
appropriate testing schedule is established for lab.appropriate testing schedule is established for lab.• Output for 2-min. TB neb. = 0.13 to 0.15 mL/min Output for 2-min. TB neb. = 0.13 to 0.15 mL/min ++ 10% 10%• Output for DeVilbiss neb. = 0.009 mL/actuation Output for DeVilbiss neb. = 0.009 mL/actuation ++ 10% 10%
• Verify concentrations of solutionsVerify concentrations of solutions
• Keep records of QC proceduresKeep records of QC procedures
SafetySafety
Precautions for Patient SafetyPrecautions for Patient Safety
• Trained staff close enough to respond quicklyTrained staff close enough to respond quicklyto an emergencyto an emergency
• Medications to treat bronchospasm must beMedications to treat bronchospasm must bepresent in testing areapresent in testing area
• A stethoscope, sphygmomanometer, A stethoscope, sphygmomanometer, and pulse oximeter should be availableand pulse oximeter should be available
Precautions for Technician SafetyPrecautions for Technician Safety
• Try to minimize technician exposureTry to minimize technician exposure
• Testing room should have adequate ventilation Testing room should have adequate ventilation (> 2 AC/hr)(> 2 AC/hr)
• Use of exhalation filters useful in TB methodUse of exhalation filters useful in TB method
• Those with asthma are at increased risk and Those with asthma are at increased risk and should take extra precautions to minimize should take extra precautions to minimize their exposuretheir exposure