Standardization of bronchial inhalation challenge procedures Hyman
Chai,
Froehlich, James
A.
Baltimore, Spector,
M.D.,
M.D., McLean,
and
Richard
Bethesda, M.D.,
Rid., Albert M.D., Denver,
Md.,
5.
Farr,
David
Mich.,
AYZYIL Arbor,
1. Colo.,
Sheffer, and
M.D.,*
A. Mathison,
II, Robert
M.D.,
Denver, M.D.,
Richard
Cob., Luz A. La Jolla, Calif.,
R. Rosenthal,
Boston,
G. Townley,
Mass., M.D.,
M.D.,
Sheldon Omaha,
I.. Xebr.
A group of investigators interested in the standardization of inhalation challenge techniques was selected by the program directors of the Asthma and Allergic Disease Centers (AADC). This effort has been assisted by the National Institute of Allergic and Infectious Diseases of the National Institutes of Health. At the last meeting of the panel on February 15, 19’75, criteria for procedures and materials used were suggested in order to standardize bronchial inhalation challenges as they pertain to allergic disease. Antigens
Aqueous antigenic extracts were diluted with a diluent containing 0.5% sodium chloride USP, 0.2’75% sodium bicarbonate, and 0.4% phenol (pH 7:O). When available, lyophilized extracts are preferable and will be utilized. Antigens will be labeled on a weight per volume basis, but the proteinnitrogen units (pnu/ml) and/or pg of protein nitrogen/ml determination of the batch should also be indicated. Limited data imply that concentrations up to 1:20 can be stored at 4O C for one year. Anything more dilute than 1:20 should be utilized within ‘7 days of preparation. Delivery
system
Although the Dosimeter developed at Johns Hopkins is suggested,t other standardized techniques also are acceptable. The Dosimeter is designed to deliver a consistent amount of solution from the connected DeVilbiss No. 42 nebulizer and is triggered by an inhalation. Twenty psi of compressed air is connected to the input valve and a convenient setting of 0.6 see is recommended for adults on the timing adjustment. All breaths of diluents, antigens, methacholke, and histamine should be delivered from functional residual capacity to inspiratory capacity. When alternate methods of delivery are utilized, these should be carefully detailed and referenced. Reprint requests to: Dr. Richard S. Farr, Chairman, Department of Jewish Hospital, 3800 E. Colfax Ave., Denver, Colo. 80206. *Panel Chairman. tInformation concerning the availability of Dosimeters can be obtained R. Rosenthal, Johns Hopkins University College of Medicine at the Good 5601 Loch Raven Blvd., Baltimore, Md. 21212. Vol.
Medicine,
National
by writing Samaritan
Richard Hospital,
56, No. 4,
pp.
3.%?-3%7
324
Chai
Concurrent
J. ALLERGY
et al.
CLIN. IMMUNOL. OCTOBER 1975
medications
Patients should be tested during an asymptomatic state, preferably not taking medications. Realizing this is not always possible for individuals who require chronic medications, we recommend the following: beta adrenergic stimulating agents, inhaled or injected, withheld for at least 8 hr; sustained release medications of the beta adrenergic stimulator and/or phosphodiesterase inhibitor type, 12 hr; cromolyn sodium, 24 hr; antihistamine agents, 48 hr; hydrosyzine, 96 hr; and alpha adrenergic blocking agents or anticholinergic agents, 8 hr. It should be emphasized that all other medications should either be withheld or given at a specified and consistent interval with reference to the inhalation challenge. Patients receiving daily corticosteriod drugs should be challenged in a constant relationship to the last dose of that medication. Patients receiving alternate-day corticosteriod drugs should not be challenged within the first 24 hr of the last dose administered. This discussion refers to the shortacting preparations such as prednisone, prednisolone, or methylprednisolone. An intradermal test with histamine at the time of inhalation challenge should be performed and, if a negative test is found, the challenge should be delayed. METHODS lntradermal
tests
The purpose of cutaneous testing is to establish safe initial dose for inhalation challenge. A 26.gauge 3/8” needle is used for intradermal (intracutaneous) injections of 0.02 ml administered to the lateral aspect of the upper arm just below the deltoid area. Serially diluted antigen extracts are given from 10-a to 10-a w/v dilutions. Unusual histories that indicate an exquisite sensitivity merit more dilute concentrations. Aqueous extracts of pollens, molds, dusts, and dander8 are used. Storage of antigens is similar to that previously discussed. The diluent control is used as well as histamine base 0.01 mg/ml. The reactions are rrad after 20 min. Skin test data are recorded as the largest diameter of the elevation produced by the diluent control subtracted from that produced by the antigen. Although data are expressed in millimeters of wheal, the following table indicates symbols that can also be utilized to designate the degree of reaction. l-2 mm > control + Continue to next higher concentration 3-5 mm > control + 6-8 mm 9-11
mm
>
control >
control
++
Stop at 2+ reaction and, if greater, titrate back to 2+
+++
12 or greater > control ++++ Pseudopods and erythema will be given no specific significance. The above refers to the largest wheal diameter. An intradermal skin test is considered definitely positive at that concentration producing >5-mm wheal minus the diluent control. The histamine injection is given to determine the patient’s skin reactivity and is a check for medication that may inhibit the skin test. The 0.01 mg/ml dilution of histamine base should produce a wheal greater than the diluent control. Ideally, the medication restrictions outlined under “Concurrent Medications” should apply to skin tests, but if this is not possible, ephedrine and aminophylline can be given prior to skin tests.
Antigen
inhalation
challenge
Asymptomatic patients are studied highest
previously
observed
value.
Ten
when minutes
the baseline FEV, following inhalation
is 80% or greater of 5 breaths of
of the diluent,
VOLUME NUMBER
56 4
Standardization
of
bronchial
inhalation
challenge
procedures
325
pulmonary function studies are repeated. This diluent value is known as the control, and if the FEV, is not reduced 10% from the baseline, the patient enters the study. The challenge usually begins with 5 breaths of the antigen concentration required to elicit a 2+ intradermal test. More dilute antigen concentrations may be used at the discretion of the investigator. The time the initial antigen inhalation is given is recorded. If less than a 15% reduction from the control FEV, value occurs 10 min postantigen, the next dilution is given. If the reduction is 15% to 19c/o, an additional 5- to lo-min wait is indicated. The 10.min drop should be sustained for a 20-min reading. The time of the final FEV, after inhalation of the most concentrated antigen tested (positive or negative) is recorded. When approaching the end point, which is a greater than 20% fall in FEV, from the diluent control test, less than 5 breaths may be given to be more cautious. When feasible, the patient should be studied at hourly intervals for a total of 10 hrs and at 24 hr to look for late reactions. When this is not possible, the investigator should be aware that late reactions do occur that may occasionally be more severe than the initial reaction. An appropriate precautionary measure regarding patient care for this contingency should be implemented. Repeat bronchial inhalation challenge with antigen may be performed no earlier than 24 hr later. Under these circumstances, the initial lower doses of antigen may be eliminated if the investigator wants to initiate challenge at that part of the dose-response curve which was approximate to the descending portion. It should be recognized that the day-to-day variabi1it.y of this test has been established at approximately tenfold and may be more depending upon the dose delivery system used. For this reason, it would be appropriate to initiate subsequent challenges at least 2 concentrations of antigen lower than that which was the first initiate a significant change from baseline or control. The following dilution increments have been found to be safe: 1:500,000, 1 :lOO,OOO, 1:50,000, 1 :lO,OOO, 1:5,000, l:l,OOO, 1:500. Concentrations of antigen that fall between dilutions listed above may be used if the investigator desires more points on his dose-response curve. Expression of the data is discussed in a subsequent section.
Methacholine
inhalation
challenge
Using the same criteria for adequate baseline as described for antigen inhalation challenge, the appropriate diluent is given. As long as there is not >lO% fall in FEV,, 5 breaths of serial dilutions of methacholine are given to the patient. Measurements will be taken at 1 and 1h min and should be sustained at the 3-min reading. A positive test is a >20% reduction from the control FEV, value. If the test is negative, 5 breaths of the next dilution will be given; if the test is borderline-positive, less than 5 breaths of the next dilution may be given. There should be a 2-hr wait between methacholine challenge and another procedure as long as the patient is back to baseline. Expression of the data will be discussed. Dilution increments found to be safe are: 0.075, 0.15, 0.31, 0.62, 1.25, 2.5, 5.0, 10.0, 250/mg/ml.
Histamine
inhalation
challenge
Using the same criteria for adequate baseline as described for antigen inhalation challenge, the appropriate diluent is given. As long as there is not >lO% fall in FEV,, 5 breaths of serial dilutions of histamine are given on successive inhalations to the patient. Measurements will be taken immediately and should be sustained at the 3-min reading. A positive test is a 3-min drop of FEV, of 20% or greater from the control FEV, value. If the test is negative, 5 breaths of the next dilution will be given; if the test is borderline-positive, less than 5 breaths of the next dilution may be given. There should be a 2.hr wait between histamine challenge and another procedure as long as the patient is back to baseline. Expression of data will be discussed. Dilution increments found to be safe are: 0.03, 0.06, 0.12, 0.25, 1.0, 2.5, 5.0, lO.O/mg/ml.
Inhaled To patient
bronchodilator test the effect of should be hetween
drug
testing
inhaled bronchodilators 50% and 80% of his
on baseline previous best
functions, the FEV, of the ag determined after broneho-
326
Chai
TABLE
I. Breath
Antigen
1:1,000,000 1:5oqooo 1:100,000 1:50,000 1:10,000 1:5,000 l:l,OOO 1:500
J. ALLERGY
et al.
units
for
antigens
Cumulative No. breaths
concentrationt
or 16-B or 2 x or 10-s or 2 x or lo-’ or 2 X or lo-’ or2 X
10-G
5 10 15 ::
lo-’
:t
IO-8
10ms
II. Breath
Methacholine concentrations (ma/ml) _.
0.075 0.15
units
I
Units/ breath
for
1:
:i 45
*One breath unit = 1 inhalation tIf final FEV, test is performed cumulative units are calculated
0.025 0.05 0.25 0.5 2.5 5.0 25.0 50.0
0.025 0.075 0.325 0.825 3.32 8.32 33.3 83.3
of 1: 5,000 w/v dilution. concentrations can be added to fit specific experimental needs. at other than a B-breath interval (i.e., 23 breaths), the by adding 3 x 0.1 = 0.3 to 0.825 = 1.12.
methacholine
Cumulative No. breaths
Cumulative units/5 breaths*
Units/5 breaths
0.005 0.01 0.05 0.1 0.5 1.0 5.0 10.0
on a mg/ml
I
Units/ breath
0.075 0.15
0.62 1.25 2.50 5.00 10.00 25.00
basis*
40
*One breath unit = 1 inhalation thdditional intermediate antigen $If final FEV, test is performed cumulative units are calculated
TABLE
on a weight/volume
CLIN. IMMUNOL. OCTOBER 1975
10.00 25.00
basis*
I
Units/5 breaths
I
0.375 0.750 1.55 3.10 6.25 12.50 25.00 50.00 125.00
of 1 mg/ml. at other than a 5-breath interval by adding 3 x 0.62 = 1.86 to 5.78 =
Cumulative units/6 breethst
0.375 1.125 2.68 5.78 12.0 24.5 49.5 99.5 225.0 (i.e., 7.64.
23 breaths),
the
the baseline should be within 20% of the dilators. When comparing bronchodilators, value for the previous study day, but no better than 80% of the best. ,,Other bronchodilators should be withheld as previously stated under “Current Medications.” Pulmonay function tests should be done as frequently as indicated within the first 15 min, if appropriate, to determine its onset of action. Most, if not all, bronchodilator testing should include 15., 30-, and 60.min readings. Hourly functions would be adequate thereafter to determine duration of action.
EXPRESSION OF DATA Antigen inhalation challenge An antigen inhalation unit, using either the Dosimeter or other suitable device, is arbitrarily defined as one inhalation of a 1:5,000 w/v dilution of antigen. The antigen concentration times the number of breaths (usually 5) equals the cumulated dose for each exposure unless fewer breaths have been used. Table I details the cumulative doses obtained after each of the exposures. If testing has not begun with the lowest concentration, then the contribution made to the cumulative dose by doses not given may be subtracted. Data should be graphed on semi-log paper so that accumulative units of antigen appear logarithmically on the abscissa as well as time on an arithmetic scale, and the per cent control FEV, is plotted arithmetically on the ordinate. A straight line is then drawn connecting the points which bracket a 20% fall in FEV,. This line will intersect the 80% level, and from this inter-
VOLUME NUMBER
56 4
TABLE
III.
Histamine concentrations hgiml)
Standardization
Breath
units
for
histamine
of
base
bronchial
inhalation
on a mg/ml
challenge
0.03 0.06 0.12 0.25 0.50 I .oo 2.50 5.00 10.00
Units/ breath
Units/B breaths
Cumulative units/5 breaths
0.03
0.15
fS 2’:
0.12 0.50 0.25
0.06
0.60 0.30 2.50 I .25
0.45 1.05 4.80 2.30
30
1.00 2.50 5.00 10.00
5.00 12.50 25.00 50.00
9_.__ 80 22.30 47.30 97.30
45
*One breath unit = 1 inhalation t If final FEV, test is performed cumulative units are calculated
of 1 mg/ml histamine base. at other than a 5-breath interval by adding 3 x 0.25 = 0.75 to 2.30 =
t
_.__
5
0 IS
:i
327
basis*
base Cumulative No. breaths
procedures
(i.e., 3.05.
23 breaths),
the
section a vertical is dropped to the abscissa. That dose is read as a provocation dose delivered over “x” number of minutes to cause a 20% fall in FEV, and is designated as PD,“-FEV,. Data are expressed as PD,-FEV, = “x” units/x’ min. The FEV, has been used throughout this protocol because it is a measurement available to most, investigators. This panel expressly encourages the construction of provocation doseresponse curves, utilizing other parameters of pulmonary functions also, e.g., specific conductance, peak flow rates, and maximum midexpiratory flow rates. When this is done, however, the provocative dose should be expressed in a manner to include: (1) the per cent reduction and/or increase required for a positive test; (2) the parameter being studied; and (3) the For example, if a 35% reduction of time during which the test substance was delivered. specific conductance were to be the provocative dose end-point, then that dose would be determined in a manner described above and expressed as PD,,-SGaw = x units/x’ min.
Methacholine
inhalation
challenge
A methacholine inhalation unit is arbitrarily defined as one inhalation of 1 mg/ml of methacholine in buffered diluent. The calculation for cumulative inhalation units as concerns methacholine on a mg/ml basis is presented in Table II. The data should be expressed in terms of PD,-FEV, = x unite/x’ min. Data involving other parameters of pulmonary function should be expressed as described for antigen inhalation challenge in “Expression of Data, Antigen Inhalation Challenge.”
Histamine
inhalation
challenge
A histamine inhalation unit is arbitrarily defined as one inhalation of 1 mg/ml of histamine base in buffered diluent. The calculations for cumulative inhalation units as concerns histamine on a mg/ml basis are presented in Table III. The data should be expressed in terms of PI),,-FEV, = x units/x’ min. Studies involving other parameters of pulmonary function should be expressed as described for antigen inhalation challenge under “Expression of Data.”
Chai,
Froehlich, James
A.
Baltimore, Spector,
M.D.,
M.D., McLean,
and
Richard
Bethesda, M.D.,
Rid., Albert M.D., Denver,
Md.,
5.
Farr,
David
Mich.,
AYZYIL Arbor,
1. Colo.,
Sheffer, and
M.D.,*
A. Mathison,
II, Robert
M.D.,
Denver, M.D.,
Richard
Cob., Luz A. La Jolla, Calif.,
R. Rosenthal,
Boston,
G. Townley,
Mass., M.D.,
M.D.,
Sheldon Omaha,
I.. Xebr.
A group of investigators interested in the standardization of inhalation challenge techniques was selected by the program directors of the Asthma and Allergic Disease Centers (AADC). This effort has been assisted by the National Institute of Allergic and Infectious Diseases of the National Institutes of Health. At the last meeting of the panel on February 15, 19’75, criteria for procedures and materials used were suggested in order to standardize bronchial inhalation challenges as they pertain to allergic disease. Antigens
Aqueous antigenic extracts were diluted with a diluent containing 0.5% sodium chloride USP, 0.2’75% sodium bicarbonate, and 0.4% phenol (pH 7:O). When available, lyophilized extracts are preferable and will be utilized. Antigens will be labeled on a weight per volume basis, but the proteinnitrogen units (pnu/ml) and/or pg of protein nitrogen/ml determination of the batch should also be indicated. Limited data imply that concentrations up to 1:20 can be stored at 4O C for one year. Anything more dilute than 1:20 should be utilized within ‘7 days of preparation. Delivery
system
Although the Dosimeter developed at Johns Hopkins is suggested,t other standardized techniques also are acceptable. The Dosimeter is designed to deliver a consistent amount of solution from the connected DeVilbiss No. 42 nebulizer and is triggered by an inhalation. Twenty psi of compressed air is connected to the input valve and a convenient setting of 0.6 see is recommended for adults on the timing adjustment. All breaths of diluents, antigens, methacholke, and histamine should be delivered from functional residual capacity to inspiratory capacity. When alternate methods of delivery are utilized, these should be carefully detailed and referenced. Reprint requests to: Dr. Richard S. Farr, Chairman, Department of Jewish Hospital, 3800 E. Colfax Ave., Denver, Colo. 80206. *Panel Chairman. tInformation concerning the availability of Dosimeters can be obtained R. Rosenthal, Johns Hopkins University College of Medicine at the Good 5601 Loch Raven Blvd., Baltimore, Md. 21212. Vol.
Medicine,
National
by writing Samaritan
Richard Hospital,
56, No. 4,
pp.
3.%?-3%7
324
Chai
Concurrent
J. ALLERGY
et al.
CLIN. IMMUNOL. OCTOBER 1975
medications
Patients should be tested during an asymptomatic state, preferably not taking medications. Realizing this is not always possible for individuals who require chronic medications, we recommend the following: beta adrenergic stimulating agents, inhaled or injected, withheld for at least 8 hr; sustained release medications of the beta adrenergic stimulator and/or phosphodiesterase inhibitor type, 12 hr; cromolyn sodium, 24 hr; antihistamine agents, 48 hr; hydrosyzine, 96 hr; and alpha adrenergic blocking agents or anticholinergic agents, 8 hr. It should be emphasized that all other medications should either be withheld or given at a specified and consistent interval with reference to the inhalation challenge. Patients receiving daily corticosteriod drugs should be challenged in a constant relationship to the last dose of that medication. Patients receiving alternate-day corticosteriod drugs should not be challenged within the first 24 hr of the last dose administered. This discussion refers to the shortacting preparations such as prednisone, prednisolone, or methylprednisolone. An intradermal test with histamine at the time of inhalation challenge should be performed and, if a negative test is found, the challenge should be delayed. METHODS lntradermal
tests
The purpose of cutaneous testing is to establish safe initial dose for inhalation challenge. A 26.gauge 3/8” needle is used for intradermal (intracutaneous) injections of 0.02 ml administered to the lateral aspect of the upper arm just below the deltoid area. Serially diluted antigen extracts are given from 10-a to 10-a w/v dilutions. Unusual histories that indicate an exquisite sensitivity merit more dilute concentrations. Aqueous extracts of pollens, molds, dusts, and dander8 are used. Storage of antigens is similar to that previously discussed. The diluent control is used as well as histamine base 0.01 mg/ml. The reactions are rrad after 20 min. Skin test data are recorded as the largest diameter of the elevation produced by the diluent control subtracted from that produced by the antigen. Although data are expressed in millimeters of wheal, the following table indicates symbols that can also be utilized to designate the degree of reaction. l-2 mm > control + Continue to next higher concentration 3-5 mm > control + 6-8 mm 9-11
mm
>
control >
control
++
Stop at 2+ reaction and, if greater, titrate back to 2+
+++
12 or greater > control ++++ Pseudopods and erythema will be given no specific significance. The above refers to the largest wheal diameter. An intradermal skin test is considered definitely positive at that concentration producing >5-mm wheal minus the diluent control. The histamine injection is given to determine the patient’s skin reactivity and is a check for medication that may inhibit the skin test. The 0.01 mg/ml dilution of histamine base should produce a wheal greater than the diluent control. Ideally, the medication restrictions outlined under “Concurrent Medications” should apply to skin tests, but if this is not possible, ephedrine and aminophylline can be given prior to skin tests.
Antigen
inhalation
challenge
Asymptomatic patients are studied highest
previously
observed
value.
Ten
when minutes
the baseline FEV, following inhalation
is 80% or greater of 5 breaths of
of the diluent,
VOLUME NUMBER
56 4
Standardization
of
bronchial
inhalation
challenge
procedures
325
pulmonary function studies are repeated. This diluent value is known as the control, and if the FEV, is not reduced 10% from the baseline, the patient enters the study. The challenge usually begins with 5 breaths of the antigen concentration required to elicit a 2+ intradermal test. More dilute antigen concentrations may be used at the discretion of the investigator. The time the initial antigen inhalation is given is recorded. If less than a 15% reduction from the control FEV, value occurs 10 min postantigen, the next dilution is given. If the reduction is 15% to 19c/o, an additional 5- to lo-min wait is indicated. The 10.min drop should be sustained for a 20-min reading. The time of the final FEV, after inhalation of the most concentrated antigen tested (positive or negative) is recorded. When approaching the end point, which is a greater than 20% fall in FEV, from the diluent control test, less than 5 breaths may be given to be more cautious. When feasible, the patient should be studied at hourly intervals for a total of 10 hrs and at 24 hr to look for late reactions. When this is not possible, the investigator should be aware that late reactions do occur that may occasionally be more severe than the initial reaction. An appropriate precautionary measure regarding patient care for this contingency should be implemented. Repeat bronchial inhalation challenge with antigen may be performed no earlier than 24 hr later. Under these circumstances, the initial lower doses of antigen may be eliminated if the investigator wants to initiate challenge at that part of the dose-response curve which was approximate to the descending portion. It should be recognized that the day-to-day variabi1it.y of this test has been established at approximately tenfold and may be more depending upon the dose delivery system used. For this reason, it would be appropriate to initiate subsequent challenges at least 2 concentrations of antigen lower than that which was the first initiate a significant change from baseline or control. The following dilution increments have been found to be safe: 1:500,000, 1 :lOO,OOO, 1:50,000, 1 :lO,OOO, 1:5,000, l:l,OOO, 1:500. Concentrations of antigen that fall between dilutions listed above may be used if the investigator desires more points on his dose-response curve. Expression of the data is discussed in a subsequent section.
Methacholine
inhalation
challenge
Using the same criteria for adequate baseline as described for antigen inhalation challenge, the appropriate diluent is given. As long as there is not >lO% fall in FEV,, 5 breaths of serial dilutions of methacholine are given to the patient. Measurements will be taken at 1 and 1h min and should be sustained at the 3-min reading. A positive test is a >20% reduction from the control FEV, value. If the test is negative, 5 breaths of the next dilution will be given; if the test is borderline-positive, less than 5 breaths of the next dilution may be given. There should be a 2-hr wait between methacholine challenge and another procedure as long as the patient is back to baseline. Expression of the data will be discussed. Dilution increments found to be safe are: 0.075, 0.15, 0.31, 0.62, 1.25, 2.5, 5.0, 10.0, 250/mg/ml.
Histamine
inhalation
challenge
Using the same criteria for adequate baseline as described for antigen inhalation challenge, the appropriate diluent is given. As long as there is not >lO% fall in FEV,, 5 breaths of serial dilutions of histamine are given on successive inhalations to the patient. Measurements will be taken immediately and should be sustained at the 3-min reading. A positive test is a 3-min drop of FEV, of 20% or greater from the control FEV, value. If the test is negative, 5 breaths of the next dilution will be given; if the test is borderline-positive, less than 5 breaths of the next dilution may be given. There should be a 2.hr wait between histamine challenge and another procedure as long as the patient is back to baseline. Expression of data will be discussed. Dilution increments found to be safe are: 0.03, 0.06, 0.12, 0.25, 1.0, 2.5, 5.0, lO.O/mg/ml.
Inhaled To patient
bronchodilator test the effect of should be hetween
drug
testing
inhaled bronchodilators 50% and 80% of his
on baseline previous best
functions, the FEV, of the ag determined after broneho-
326
Chai
TABLE
I. Breath
Antigen
1:1,000,000 1:5oqooo 1:100,000 1:50,000 1:10,000 1:5,000 l:l,OOO 1:500
J. ALLERGY
et al.
units
for
antigens
Cumulative No. breaths
concentrationt
or 16-B or 2 x or 10-s or 2 x or lo-’ or 2 X or lo-’ or2 X
10-G
5 10 15 ::
lo-’
:t
IO-8
10ms
II. Breath
Methacholine concentrations (ma/ml) _.
0.075 0.15
units
I
Units/ breath
for
1:
:i 45
*One breath unit = 1 inhalation tIf final FEV, test is performed cumulative units are calculated
0.025 0.05 0.25 0.5 2.5 5.0 25.0 50.0
0.025 0.075 0.325 0.825 3.32 8.32 33.3 83.3
of 1: 5,000 w/v dilution. concentrations can be added to fit specific experimental needs. at other than a B-breath interval (i.e., 23 breaths), the by adding 3 x 0.1 = 0.3 to 0.825 = 1.12.
methacholine
Cumulative No. breaths
Cumulative units/5 breaths*
Units/5 breaths
0.005 0.01 0.05 0.1 0.5 1.0 5.0 10.0
on a mg/ml
I
Units/ breath
0.075 0.15
0.62 1.25 2.50 5.00 10.00 25.00
basis*
40
*One breath unit = 1 inhalation thdditional intermediate antigen $If final FEV, test is performed cumulative units are calculated
TABLE
on a weight/volume
CLIN. IMMUNOL. OCTOBER 1975
10.00 25.00
basis*
I
Units/5 breaths
I
0.375 0.750 1.55 3.10 6.25 12.50 25.00 50.00 125.00
of 1 mg/ml. at other than a 5-breath interval by adding 3 x 0.62 = 1.86 to 5.78 =
Cumulative units/6 breethst
0.375 1.125 2.68 5.78 12.0 24.5 49.5 99.5 225.0 (i.e., 7.64.
23 breaths),
the
the baseline should be within 20% of the dilators. When comparing bronchodilators, value for the previous study day, but no better than 80% of the best. ,,Other bronchodilators should be withheld as previously stated under “Current Medications.” Pulmonay function tests should be done as frequently as indicated within the first 15 min, if appropriate, to determine its onset of action. Most, if not all, bronchodilator testing should include 15., 30-, and 60.min readings. Hourly functions would be adequate thereafter to determine duration of action.
EXPRESSION OF DATA Antigen inhalation challenge An antigen inhalation unit, using either the Dosimeter or other suitable device, is arbitrarily defined as one inhalation of a 1:5,000 w/v dilution of antigen. The antigen concentration times the number of breaths (usually 5) equals the cumulated dose for each exposure unless fewer breaths have been used. Table I details the cumulative doses obtained after each of the exposures. If testing has not begun with the lowest concentration, then the contribution made to the cumulative dose by doses not given may be subtracted. Data should be graphed on semi-log paper so that accumulative units of antigen appear logarithmically on the abscissa as well as time on an arithmetic scale, and the per cent control FEV, is plotted arithmetically on the ordinate. A straight line is then drawn connecting the points which bracket a 20% fall in FEV,. This line will intersect the 80% level, and from this inter-
VOLUME NUMBER
56 4
TABLE
III.
Histamine concentrations hgiml)
Standardization
Breath
units
for
histamine
of
base
bronchial
inhalation
on a mg/ml
challenge
0.03 0.06 0.12 0.25 0.50 I .oo 2.50 5.00 10.00
Units/ breath
Units/B breaths
Cumulative units/5 breaths
0.03
0.15
fS 2’:
0.12 0.50 0.25
0.06
0.60 0.30 2.50 I .25
0.45 1.05 4.80 2.30
30
1.00 2.50 5.00 10.00
5.00 12.50 25.00 50.00
9_.__ 80 22.30 47.30 97.30
45
*One breath unit = 1 inhalation t If final FEV, test is performed cumulative units are calculated
of 1 mg/ml histamine base. at other than a 5-breath interval by adding 3 x 0.25 = 0.75 to 2.30 =
t
_.__
5
0 IS
:i
327
basis*
base Cumulative No. breaths
procedures
(i.e., 3.05.
23 breaths),
the
section a vertical is dropped to the abscissa. That dose is read as a provocation dose delivered over “x” number of minutes to cause a 20% fall in FEV, and is designated as PD,“-FEV,. Data are expressed as PD,-FEV, = “x” units/x’ min. The FEV, has been used throughout this protocol because it is a measurement available to most, investigators. This panel expressly encourages the construction of provocation doseresponse curves, utilizing other parameters of pulmonary functions also, e.g., specific conductance, peak flow rates, and maximum midexpiratory flow rates. When this is done, however, the provocative dose should be expressed in a manner to include: (1) the per cent reduction and/or increase required for a positive test; (2) the parameter being studied; and (3) the For example, if a 35% reduction of time during which the test substance was delivered. specific conductance were to be the provocative dose end-point, then that dose would be determined in a manner described above and expressed as PD,,-SGaw = x units/x’ min.
Methacholine
inhalation
challenge
A methacholine inhalation unit is arbitrarily defined as one inhalation of 1 mg/ml of methacholine in buffered diluent. The calculation for cumulative inhalation units as concerns methacholine on a mg/ml basis is presented in Table II. The data should be expressed in terms of PD,-FEV, = x unite/x’ min. Data involving other parameters of pulmonary function should be expressed as described for antigen inhalation challenge in “Expression of Data, Antigen Inhalation Challenge.”
Histamine
inhalation
challenge
A histamine inhalation unit is arbitrarily defined as one inhalation of 1 mg/ml of histamine base in buffered diluent. The calculations for cumulative inhalation units as concerns histamine on a mg/ml basis are presented in Table III. The data should be expressed in terms of PI),,-FEV, = x units/x’ min. Studies involving other parameters of pulmonary function should be expressed as described for antigen inhalation challenge under “Expression of Data.”
