PRAS00N JAIN, MD Dr. Jain is a fellow in the Department of Pulmonary and Critical Care Medicine at the Cleveland Clinic.

MANI S. KAVURU, MD Dr. Kavuru is director of the Pulmonary Function Laboratory at the Cleveland Clinic.

A practical guide for monitoring in patients

• KEY POINTS: • ABSTRACT: The peak expiratory flow rate is an objective measure of As many as 15% of patients cannot airflow obstruction that patients can learn with little difficulty, and which perceive severe airflow obstruction, provides physicians objective information for assessing a patient's condi- and studies show that physicians often tion. We outline how to use peak flow monitoring as part of an asthma misjudge the severity of asthma attacks. treatment plan. n assessing and treating asthma, the signs and symptoms are not Peak flow monitoring at home is enough: many patients and physicians alike underestimate the indicated for patients older than 5 severity of airway obstruction. To obtain objective information, we years with moderate to severe asthma, advocate measuring the peak expiratory flow (PEF, or peak flow) and gives physicians an objective rate. Our patients with moderate to severe asthma measure their assessment of airflow obstruction. Ipeak flow at home using inexpensive, compact meters and record the readings in an asthma diary, which we review at follow-up visits. A reading of 50% or less of the patient's personal best peak flow • WHY MEASURE PEAK FLOW? reading indicates quick action is Recent advances in understanding the pathogenesis of asthma have needed, while a reading of 50% to shifted the emphasis of treatment. Instead of controlling the symptoms 80% indicates a potential problem. of bronchospasm only with inhaled beta2 agonists and methylxan- thines, we also try to control the underlying chronic airway inflamma- Patient education is crucial and must tion with inhaled anti-inflammatory agents.1 include specific instructions on what to However, these advances have not translated into improved con- do in case of low peak flow readings. trol in the general asthmatic population. Approximately 5% of adults and 10% of children in the United States have asthma, and its preva- lence seems to be increasing, especially in children. From 1982 through 1991, the rate of death due to asthma increased by 62% in the United States.2 Hospital admissions for asthma have increased in recent years. Possible reasons for these trends are inadequate access to health care, suboptimal maintenance pharmacotherapy, and delay in starting appropriate therapy because patients, relatives, and physicians fail to recognize the severity of an asthma attack.

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997 2 1 3

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. PEAK EXPIRATORY FLOW MONITORING • JAIN AND KAVURU LJ

TABLE 1 volume in 1 second (FEVJ that is less than 50% of predicted.^ No demographic or clin- RATIONALE FOR PEAK EXPIRATORY FLOW MONITORING ical feature can help the physician predict which patients will be "good perceivers" or At home "poor perceivers."

To detect worsening airflow obstruction early in patients, who may perceive symptoms poorly Clinical signs are also unreliable Hyperinflation and wheezing that is high- To guide patients in taking medications pitched, loud, and biphasic are thought to be To improve asthma control signs of severe airflow obstruction. However, To reduce asthma-related morbidity several studies have shown that even experi- enced physicians often misjudge the severity To improve perception of acute airflow obstruction of an asthma attack,^5 and data suggests that patients can gauge the severity of an attack In the emergency department better than their physicians can.6 To objectively assess the severity of asthma attacks

To assess response to therapy Underestimating asthma severity leads to undertreatment To predict early the need for hospital admission Physicians and patients need an objective To Identify need for arterial blood gas analysis measure of airflow obstruction to guide them

To predict relapse after discharge from the emergency department in managing asthma attacks promptly, because underestimating the severity of airflow obstruction can delay appropriate therapy. In hospitalized patients Such delay may allow function to worsen To assess therapeutic response progressively, predisposing patients to near- To document clinical improvement at discharge fatal asthma attacks and placing them at high- er risk of asthma-related death.

In Peak flow monitoring is practical To demonstrate airflow obstruction at the workplace The peak flow rate is the most practical mea- To identify asthma triggers sure in outpatients,7-9 as the monitoring devices are inexpensive (costing from $15 to

••••••••••^^••••••••••••••••••••••••MHBHMHHlI $40), portable, and easy to use. Patients as young as 5 years can master the technique with Patients' perceptions of symptoms are unreliable minimum training and keep an accurate record. The patient's own perceptions of chest tight- Admittedly, the FEVi is more accurate, as ness, cough, wheezing, and shortness of breath it reflects changes in large and medium-sized strongly influence the treatment he or she airways, whereas the peak flow reading reflects receives. When patients seek advice over the changes in the large airways only. Peak flow telephone, these perceptions are often the readings correlate well with FEV| readings, only kind of information available to the but not uniformly. Therefore, a peak flow physician. reading is not an adequate substitute for office Unfortunately, these symptoms are . However, serial peak flow mea- unreliable. Numerous clinical and experi- surements are acceptable for monitoring lung mental studies show that many asthma function. patients cannot accurately evaluate the severity of airflow obstruction. As many as Studies have been equivocal 15% of patients cannot perceive even severe Studies that compared the outcomes of airflow obstruction—a forced expiratory patients treated according to peak flow val-

196 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. ues vs symptoms have yielded conflicting expensive equip- TABLE 2 results. The failure to show clear benefit of ment, has a greater INDICATIONS FOR PEAK management based on peak flow readings clinical value than EXPIRATORY FLOW MONITORING compared with conventional management is the peak flow read- AT HOME very controversial, and may be the result of ing. Studies showed differences in "action points" used in the that patients who Moderate to severe asthma studies. needed hospital ad- Labile and poorly controlled symptoms Most studies of outcomes used peak flow mission after receiv- values of less than 70% of the patient's per- ing initial care in Increasing need for rescue beta2 agonists sonal best as an initial indication to alter the the emergency de- Repeated need for oral prednisone therapy treatment, or "action point." In a recent partment had lower Frequent emergency visits for asthma 10 study, Gibson and colleagues found a better peak flow rates both exacerbations peak flow-based action point: readings on 2 at initial presenta- Recent hospital admission for asthma of 3 consecutive days that were between 2 tion and at the time and 3 standard deviations below the patient's of disposition from Near-fatal asthma attack mean value. This criterion was significantly the emergency Poor perception of asthma symptoms more sensitive and specific than criteria room.20'21 Peak flow based on a percentage of the patient's per- monitoring may sonal best reading and detected exacerba- reduce the need for tions several days sooner, at least in retro- arterial blood gas analysis in as many as 40% spect. of patients receiving emergency therapy for Nevertheless, we believe that peak flow asthma exacerbations.22-23 Practice guidelines monitoring has a sound and logical rationale based on peak flow monitoring have been (TABLE 1) and we will discuss our specific rec- shown to reduce unnecessary hospital admis- ommendations for action points in the section sions.24 on practical recommendations, below. The National Asthma Education and On the basis of frequency of asthma symp- Prevention Program recommends peak flow toms, peak expiratory flow (expressed as a per- monitoring for all patients with acute asthma centage of the patient's personal best score), exacerbation and suggests that the peak flew and peak flow variability, asthma is classified value should be at least 70% of the predicted as mild, moderate, and severe. value at the time of discharge from the emer- Measure the Patients with mild asthma do not need gency department.25 Unfortunately, many peak flow rate peak flow monitoring,11-13 but patients with physicians do not measure the peak flow rate before and 10 to moderate to severe asthma appear to bene- in this situation. Also, patients do not typical- 15 minutes after fit,13-15 because it facilitates close monitoring ly receive clear instructions about peak flow giving a beta2 of lung function and may promote use of monitoring before discharge.26 agonist inhaled steroids and early institution of oral In these patients, the peak flow should be steroid therapy whenever appropriate. measured before starting therapy and fre- In many randomized studies that com- quently thereafter. Measuring the peak flow pared peak flow-based management with con- before and 10 to 15 minutes after giving a ventional symptom-based treatment, the out- beta2 agonist provides a fair assessment of how comes improved even in the control groups, well bronchospasm responds to inhaled bron- probably because all patients in these studies chodilators in the short term. In addition, the received asthma education. These findings peak flow should be measured at the time of concur with those in previous studies of asth- discharge from the emergency department, to ma education.16-18 document that airflow has improved. In hospitalized patients. Peak flow mon- Special uses of peak flow monitoring itoring is performed in 15% to 80% of patients In the emergency department. Patients admitted to the hospital with acute asthma frequently undergo peak flow monitoring dur- exacerbations.26-28 How physicians use the ing emergency care for acute asthma exacer- information is unclear. Pulmonary physicians bations. Objective monitoring of lung func- follow the peak flow rate more often than do tion leads to a change in treatment in up to internists in hospitalized asthma patients.29 20% of patients with acute asthma exacerba- Whether monitoring the peak flow rate tions.19 There is no evidence that the FEVi, improves the outcome in hospitalized patients which requires more sophisticated and is unknown.

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997 2 07

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. PEAK EXPIRATORY FLOW MONITORING it JAIN AND KAVURU

• PRACTICAL RECOMMENDATIONS can also measure the FEVi, forced vital capac- FOR HOME PEAK FLOW MONITORING ity (FVC), and the forced expiratory flow,

mid-expiratory phase (FEF250/0_750/0). Their Successful asthma treatment requires that main advantage is the ease with which they patients participate actively in their care. The can store and retrieve data, obviating the need essential components of a well-constructed for manual record-keeping. Some can down- therapeutic program are patient education, load data over the telephone to the physician's environmental control, and carefully tailored computer for subsequent review. pharmacotherapy based on objective assess- On the other hand, electronic peak flow ment of lung function. meters cost considerably more than mechani- Prescribing a peak flow meter without a cal ones. Even though the peak expiratory well-constructed asthma management plan is flow measured by hand-held electronic unlikely to improve patient outcome. Rather, devices and office maintains a lin- peak flow monitoring provides another piece ear relationship over a wide range of observa- of information that should be carefully inter- tions, these electronic instruments are not preted in the overall clinical context. accurate enough to substitute for office-based spirometry. We do not believe that electronic Patient selection peak flow meters represent a major break- Not all patients require or benefit from peak through or offer any major advantage in rou- flow monitoring, but we believe it is useful tine clinical practice. for patients at higher risk of asthma-related morbidity and mortality (TABLE 2). The Patient education is crucial National Asthma Education and Prevention The FIGURE summarizes how patients should Peak flow Program (NAEPP) guidelines recommend measure their peak flow, and what they should monitoring is home peak flow monitoring for all patients do if they have abnormal readings. Because useful for older than 5 years with moderate to severe the peak flow occurs within the first 100 mil- patients at asthma.",30,31 liseconds of the forced expiration,56 a pro- higher risk longed expiratory effort is unnecessary. Which peak flow meter to choose? We ask patients to keep a simple asthma A variety of small, inexpensive peak flow diary, which we review during each outpatient meters are available for home use. All must visit. The diary contains their peak flow read- meet NAEPP guidelines for accuracy and pre- ings and how many puffs of a beta2 agonist cision52^: readings must be within 10% of they used each day. those obtained with a standard Wright peak In the beginning, patients measure their flow meter, and successive readings must come peak flow rate twice a day, upon waking up within 5% of each other if measured with the and in the evening; all readings are taken same device, and within 10% of each other if before taking any inhaled . measured with different devices from the same Once they achieve good asthma control, manufacturer. patients can measure their peak flow rate less Because most of these inexpensive devices frequently, such as once a day or even 2 to 3 can detect a 2% to 5% change in peak flow, times per week. If they do so, however, they most experts agree that they are adequate for should always measure it at the same time of serial monitoring. However, because the vari- day, preferably in the morning before taking ation between devices made by different man- any bronchodilators. ufacturers is unpredictable, once a patient has chosen a device, he or she should use the same How to interpret the readings brand for all subsequent monitoring. The normal range for peak flow is 500 to 700 Portable electronic meters have gained L/min for men, and 380 to 500 L/min for some popularity in recent years.34,35 Although women. Peak flow rates vary with age, sex, some can only measure the peak flow, most race, height, smoking history, respiratory mus-

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 19972 1 3

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. FIGURE How to use a peak flow meter

1. Slide the marker to the bottom of the scale (close to the mouthpiece). 2. Stand or sit upright.

3. Take a deep breath. 4. Place the meter in your mouth. 5. Make your lips tight around the mouthpiece. 6. Blow as hard and as fast as possible. 7. Take the meter out of your mouth, look at the reading, and write it down.

8. Repeat the same steps two more times.

9. Record the highest of the three readings in your Asthma Diary.

Tabs If your highest of the three readings is in the: Your doctor will set these to mark 800 -f f- Green zone: \ 1-750 the three zones at 4 Congratulations. Keep up the good work. 80% and 50% of 7004 14 your personal best •ti -650 reading. 600 4 f| Yellow zone: -550 4 Take two to four puffs from your 500-r jr YN inhaler (for example, Alupent, Proventil, Ventolin, Marker |^-450 V or a similar product) every 15 to 20 minutes for 400-z 1 hour, and then measure your peak flow three 4 -350 times again. 300-^ 1 | If the best of the second three readings is 4 -250 in the green zone: 200 4 4- Continue taking the inhaler every 3 to 4 hours 4| 4150 for the next 24 hours.

100- If the best of the second three readings is still 60 in the yellow zone: Call your doctor.

Red zone: Take your bronchodilator inhaler, and call your doctor immediately. Mouthpiece

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997 2 1 3

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. ri PEAK EXPIRATORY FLOW MONITORING • JAIN AND KAVURU LJ

TABLE 1

AN ASTHMA TREATMENT PLAN BASED ON PEAK EXPIRATORY FLOW RATE

Step Severity Symptoms Peak flow* Variability Treatment

1 Mild, Any: < 1/week > 80% < 20% Inhaled beta2 agonists as needed intermittent At night: < 2/month

2 Mild, Any: Vweek-1/day > 80% 20%-30% Inhaled steroid (200-800 (jg/day)

persistent At night: > 2/month Long-acting inhaled beta2 agonist or sustained release theophylline at bedtime for nocturnal symptoms

Inhaled beta2 agonists as needed

Moderate, Any: daily 60%-80% > 30% Inhaled steroid (800-2000 pg/day) persistent At night: > 1/week If symptoms persist, add long-acting inhaled

Need for daily beta2 agonist or sustained release theophylline

beta2 agonists or both

Inhaled beta2 agonists as needed

Severe, Any: continuous < 60% > 30% Inhaled steroids (800-2000 j_ig/day)

persistent At night: frequent Add inhaled long-acting beta2 agonist Frequent exacerbations Add sustained-release theophylline Limitation of physical Add inhaled nedocromil sodium

activity Inhaled beta2 agonists as needed Oral steroids as rescue therapy

"Peak expiratory flow as a percent of the patient's personal best value

iMmMMiyiiuwmwMrini

cle strength, and effort. If the patient always jects.37 Morning and evening values may vary gives the same effort, a change in the peak as much as 10% in normal subjects and even flow rate reflects a change in the caliber of the more in asthma patients, especially those with large airways; however, the peak flow rate may poor asthma control.38'59 be normal in patients with significant small- Some sudden deaths have occurred in airway obstruction. patients with diurnal variations greater than Establish the "personal best" value. 20%, suggesting that excessive diurnal varia- Although nomograms based on age, height, tion indicates an unstable situation and possi- weight, and sex are available, the most useful bly identifies patients at higher risk of fatal or value that needs to be established at the out- near-fatal asthma attacks. Recent studies sug- set is the "personal best"—the highest peak gest that a morning dip in peak flow is a reli- flow reading that a patient can achieve during able marker of nocturnal bronchospasm and an asymptomatic period. We recommend cal- poor asthma control.^ culating each peak flow reading as a percent- We tell our patients to watch for any age of the patient's personal best value: excessive drop in their morning peak flew (observed value / personal best value) X 100. value, or "morning dip." The diurnal variation Watch for "morning dip." For reasons is calculated as: [(maximum value - minimum that are not understood, peak flow values are value) / 0.5 (maximum + minimum value)] x lower in the morning than in the evening, 100. Long-term therapy with inhaled steroids both in asthma patients and in normal sub- can reduce the morning dip in peak flow.41

200 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. Using peak flow readings in managing asthma TABLE 2 TABLE 3 shows a typical stepped-care approach to asthma treatment in which the treatment LIMITATIONS OF PEAK FLOW MONITORING intensity is based on symptom severity and on peak flow monitoring. Technical To help patients to manage their asthma Effort-dependent more effectively at home, the NAEPP guide- lines suggest using a system of three color- Does not reflect small-airway obstruction coded peak flow zones: Potential for unrecognized device malfunction • Green—80% to 100% of the person- al best score. Clinical usefulness

• Yellow—50% to 80% of the personal Cannot substitute for spirometry in initial best score. diagnosis • Red—less than 50% of the personal No role in mild asthma best score.25 Some peak flow meters have slid- ing tabs, which the physician can set to mark Inaccurate measurement may promote overmedication these three zones (FIGURE); on others we use Overreliance may delay seeking medical advice pieces of tape or colored felt-tipped markers. If readings remain in the green zone and Other the patient has no symptoms for a sufficient May contribute to noncompliance period, a reduction in the medication dosage can be attempted. Unfortunately, no definite Potential for fungal contamination of device recommendation about dosage reduction can be given. If readings are in the yellow zone and symptoms are worsening, the patient should changes with age, the personal best value use an inhaled beta2 agonist (two to four must be re-established every year, especially in puffs every 15 to 20 minutes for up to 1 hour) young patients. and then measure the peak flow again. If the repeat reading is in the green zone, we tell Limitations of peak flow monitoring Re-establish the the patient to continue taking the inhaled Peak flow monitoring has several limitations beta2 agonist every 3 to 4 hours for the next (TABLE 4). Perhaps the most serious of these is personal best 24 hours, and together we try to identify the the potential for inappropriate therapeutic value every year "trigger" that caused the attack. Failure of action based on an inaccurate peak flow record. peak flow to improve after 1 hour of inten- A consistent trend of change in peak flow is sive bronchodilator treatment indicates a more convincing evidence for altering therapy more severe asthma exacerbation. In that than an isolated finding. event, we start a course of oral prednisone Because regular peak flow monitoring and and advise the patient to continue taking the record-keeping requires considerable commit- inhaled bronchodilator every hour. We ment, patient compliance is a substantial advise patients to go to the emergency problem. department if the asthma attack does not reverse within 6 hours of this treatment. Safety Readings in the red zone require prompt Peak flow monitoring is generally safe. treatment with bronchodilators and oral Perhaps the most harm it can do is to mis- prednisone, and a visit to the emergency lead patients and physicians if the readings department if no response occurs within 1 are inaccurate, although there is no evi- hour. dence to suggest this actually happens. In a few patients, the forced expiratory maneuver Follow-up may precipitate bronchospasm; these The patient's technique for measuring the patients should not perform peak flow mon- peak flow should be reassessed at regular inter- itoring. vals. Although most peak flow meters func- Fungal contamination of peak flow tion adequately for 1 to 2 years, they some- devices sometimes occurs.42 Therefore, times fail prematurely. Therefore, their accu- patients should gently wash the device with racy should be validated against office spirom- soap and warm water regularly, according to etry on a periodic basis. Because the peak flow the manufacturer's recommendations.

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 1997 2 07

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. n PEAK EXPIRATORY FLOW MONITORING E JAIN AND KAVURU

• REFERENCES 22. Martin TG, Elenbass RM, Pingleton SH. Use of peak expiratory flow rates to eliminate unnecessary arterial blood gas in acute asthma. Ann 1. Kavuru MS, Pien L, Litwin D, Erzurum S, Ahmad M. Asthma: current Emerg Med 1982; 11:70-73. controversies and emerging therapies. Cleve Clin J Med 1995; 23. Nowak RM, Tomlanovich MC, Sarkar DD, Kvale PA, Anderson JA. 62:293-304. Arterial blood gases and pulmonary function testing in acute bronchial 2. Centers for Disease Control and Prevention. Asthma-United States, asthma. JAMA 1983; 249:2043-2046. 1982-1992. MMWR 1995; 43:952-955. 24. Taylor MRH. Asthma: audit of peak flow rate guidelines for admission 3. Rubinfeld AR, Pain MCF. Perception of asthma. Lancet 1976; and discharge. Arch Dis Child 1994; 70:432-434. 1:882-884. 25. National Heart, Lung and Blood Institute, National Asthma 4. McFadden ER Jr, Kiser R, deGroot WJ. Acute bronchial asthma. Education Program Expert Panel. Guidelines for the diagnosis and Relation between clinical and physiologic manifestations. N Engl J management of asthma. J Allergy Clin Immunol 1991; 88:425-534. Med 1973; 228:221-225. 26. Kuo E, Kesten S. A retrospective comparative study of in-hospital 5. Pratter MR, Hingston DM, Irwin RS. Diagnosis of bronchial asthma management of : 1984 vs. 1989. Chest 1993; by clinical evaluation. An unreliable method. Chest 1983; 84:42-47. 103:1655-1661. 6. Shim CS, Williams MH. Evaluation of the severity of asthma: patients 27. Bucknall E, Robertson C, Moran F, Stevenson RD. Management of versus physicians. Am J Med 1980; 68:11-13. asthma in hospital: a prospective audit. Br Med J 1988; 7. Clark NM, Evans D, Mellins RB. Patient use of peak flow monitoring. 296:1637-1639. Am Rev RespirDis 1992; 154:722-725. 28. Spevetz A, BartterT, Dubois J, Pratter MR. Inpatient management of 8. Cross D, Nelson HS. The role of the peak flow meter in the diagnosis status asthmaticus. Chest 1992; 102:1392-1396. and management of asthma. J Allergy Clin Immunol 1991; 29. Osman J, Ormerod P, Stableforth D. Management of acute asthma: a 87:120-128. survey of hospital practice and comparison between thoracic and gen- 9. Li JTC. Home peak expiratory flow rate monitoring in patients with eral physicians in Birmingham and Manchester. Br J Dis Chest 1987; asthma. Mayo Clin Proc 1995; 70:649-656. 81:232-241. 10. Gibson PG, Wlodarczyk J, Hensley MJ, Murree- Allen K, Olson LG, 30. British Thoracic Society. Guidelines on the management of asthma. Saltos N. Using quality-control analysis of peak expiratory flow record- Thorax 1993; 48(Suppl):Sl-S24. ings to guide therapy for asthma. Ann Intern Med 1995; 123:488-492. 31. International consensus report on diagnosis and treatment of asthma. 11. Charlton I, Charlton G, Broomfield J, Mullee MA. Evaluation of peak Eur Respir J 1992; 5:601-641. flow and symptom only >,elf management plans for control of asthma in 32. American Thoracic Society. Standardization of spirometry. 1994 general practice. Br Med J 1991; 301:1355-1359. update. Am J Respir Crit Care Med 1995; 152:1107-1 I 36. 12. Jones KP, Mullee MA, Middleton M, Chapman E, Holgate ST and the 33. Cherniack RM, Chatbum R, Gardner RM, er al. Statement on techni- British Thoracic Society Research Committee. Peak flow based asthma cal standards for peak flow meters. Bethesda (MD): National Institute self management: a randomized controlled study in general practice. of Health, 1992 (publication No. Nil 1 92- 21 1 3a). Thorax 1995; 50:851-857. 34- Wiltshire N, Kendrick AH. Evaluation of a new electronic : I 3. Grampian asthma study ol integrated care (GRASS1C). Effectiveness the vitalograph "Escort" spirometer. Thorax 1994; 49:175-178. of routine self-monitoring ot peak flow in patients with asthma. Br 35. Rebuck DA, Hanania NA, D'Urzo AD, Chapman KR. The accuracy Med J 1994; 308:564-567. of a handheld portable spirometer. Chest 1996; 109:152-157. 14. Beasley R, Cushley M. Holgate ST. A self management plan in the 36. Wright BM, McKerrow CB. Maximum forced expiratory flow rate as a treatment of adult asthma. Thorax 1989; 44:200-204. measure of ventilatory capacity. Br Med J 1959; 2:1041. 1 5. Ignacio-Garcia JM, Gonzalez-Santos P. Asthma self-management edu- 37. Hetzel MR. The pulmonary clock (editorial). Thorax 1981; cation program by home monitoring of peak expiratory flow. Am J 36:481-486. Respir Grit Care Med 1995; 151:353-359. 38. I letzel MR, Clark TJH. Comparison of normal and asthmatic circadi- 16. Allen RM, Jones MP, Oldenburg B. Randomized trial of an asthma an rhythms in peak expiratory flow rate. Thorax 1980; 35:732—738. self-management program for adults. Thorax 1995; 50:731-738. 39. Bagg LR, Hughes DTD. Diurnal variation in peak expiratory flow in 17. Wilson SR, Scamagas P, German DF, et al. A controlled trial of two asthmatics. Eur J Respir Dis 1980; 61:298- 302. forms of self-management education for adults with asthma. Am J Med 40. Bellia V, Visconti A, Insalaco G, Cuttitta G, Ferrara G, Bonsignore G. 1993; 94:564-576. Validation of morning dip of peak expiratory flow as an indicator of 18. Mayo PH, Richman J, Harris W. Results of a program to reduce admis- the severity of nocturnal asthma. Chest 1988; 94:108-110. sions for adult asthma. Ann Intern Med 1990; 112:864-871. 41. Horn CR, Clark TJH, Cochrane GM. Inhaled therapy reduces morn- 19. Emerman CL, Cydulka RK. Effect of pulmonary function testing on ing dips in asthma. Lancet 1984; 1:1143- 1145. the management of acute asthma. Arch Intern Med 1995; 42. Ayres JG, Whitehead J, Boldy DAR, Dyas A. Fungal contamination of 155:2225-2228. mini peak flow meters. Respir Med 1989; 83:503-504. 20. Kwong T, Town 1, Holst PE, Beasley R. A study of the management of asthma in a hospital emergency room. N Z Med J 1989; 102:547-549. 21. Chidley KE, Wood-Baker R, Town 1, Sleet A, Holgate ST. ADDRESS REPRINT REQUESTS to Mani S. Kavuru, MD, Department of Reassessment of asthma management in an accident and emergency Pulmonary and Critical Care Medicine, A90, The Cleveland Clinic Foundation, department. Respir Med 1991; 85:373-377. 9500 Euclid Avenue, Cleveland, OH 44195.

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 64 • NUMBER 4 APRIL 19972 1 3

Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission.