Are Our Patients With Asthma Still Using Inhalers Incorrectly?

Transcripción

1 Are Our Patients With Asthma Still Using Inhalers Incorrectly? X. Flor Escriche, a M. Rodríguez Mas, b L. Gallego Álvarez, c I. Álvarez Luque, b J. Juvanteny Gorgals, d M.M. Fraga Martínez, e and L. Sánchez Pinacho e Aim. To determine how skilled our patients with asthma are in performing different steps in the use of different inhalation devices, and to identify variables that may influence correct inhalation technique (IT). Design. Descriptive, cross-sectional study. Setting. An urban primary care center. Participants. 141 patients with asthma. Main outcome measures. Performance of a practical test to evaluate each step in IT for different devices according to SEPARsemFYC guidelines. One point was scored for each step that was performed correctly, and the technique was considered correct if the total score was >9. The main outcome variable was the percentage of patients who performed the IT correctly. Results. About three-fourths of the participants (77.3%) were women; mean age was 56.08±18.99 years. Inhalation technique was incorrect in 53.9% of the patients (51.06% of those who used a pressurized canister inhaler, 59.1% of those who used a PCI+spacer, 38.5% of those who used a Turbuhaler, and 37.5% of those who used an Accuhaler). The highest error rates were seen in exhaling completely before beginning the inhalation (63.78%), holding the breath after inhalation for as long as possible (65.94%), and breathing out slowly after the inhalation (64.86%). Better IT was seen in younger patients with higher levels of education (P=.007). There were no statistically significant differences in the rest of the variables. Conclusions. A large percentage of patients performed inhalations incorrectly. We cannot conclude that any given device is superior. The variables related with correct IT were age and level of education. Greater health education efforts are needed to teach patients how to use inhalation systems correctly. Key words: Asthma. Inhalation technique. Health education. Primary care. SIGUEN UTILIZANDO INCORRECTAMENTE LOS INHALADORES NUESTROS PACIENTES ASMÁTICOS? Objetivo. Conocer la destreza de nuestros pacientes asmáticos en la realización de las maniobras de los diferentes sistemas de inhalación, así como determinar las posibles variables que puedan influir en la correcta realización de la técnica inhalatoria (TI). Diseño. Estudio descriptivo transversal. Emplazamiento. Centro de atención primaria urbano. Participantes. Un total de 141 asmáticos. Mediciones principales. Realización de un test práctico donde se evaluaba paso a paso la TI para cada uno de los diferentes sistemas de inhalación siguiendo las normativas SEPAR-SemFYC. Por cada maniobra correctamente realizada, se asignaba un punto. La técnica se consideraba correcta si se obtenía una puntuación total > 9. La variable principal fue el porcentaje de pacientes que realizaban bien la TI. Resultados. Un 77,3% eran mujeres, con una media de edad de 56,08 ± 18,99 años. La TI fue incorrecta en el 53,9% de los pacientes (el 51,06% de los que utilizaban inhalador de cartucho presurizado [ICP], el 59,1% de los ICP + cámara, el 38,5% de Turbuhaler y el 37,5% Accuhaler). Las maniobras con mayor porcentaje de error fueron: espiración previa a la inhalación (63,78%), mantenimiento de la apnea postinspiración (65,94%), espiración lenta tras la inhalación (64,86%). A menor edad y mayor nivel de estudios, se constataba una mejor realización de la TI (p = 0,007). No se encontraron diferencias estadísticamente significativas en el resto de variables. Conclusiones. Se produjo un elevado porcentaje de pacientes con TI incorrecta. No podemos concluir que exista un sistema mejor que otro. Las variables relacionadas con la correcta realización de la TI son la edad y el nivel de estudios. Es necesario intensificar la educación sanitaria sobre el manejo de los diversos sistemas de inhalación. Palabras clave: Asma. Técnica inhalatoria. Educación sanitaria. Atención primaria. Spanish version available at A commentary follow this article (pág. 274) a Médico especialista en Medicina Familiar y Comunitaria, EAP Chafarinas. Tutor extrahospitalario, programa docente de Medicina Familiar y Comunitaria. Profesor asociado, Facultad de Medicina, Universitat Autònoma de Barcelona. Miembro del grupo de asma de la Societat Catalana de Medicina Familiar i Comunitària. Responsable de investigación SAP Nou Barris, Barcelona, Spain. b Médico residente de Medicina Familiar y Comunitaria, EAP Chafarinas, Barcelona, Spain. c Médico especialista en Medicina Familiar y Comunitaria, EAP Guineueta. Miembro del grupo de asma de la Societat Catalana de Medicina Familiar i Comunitària, Barcelona, Spain. d Médico especialista en Medicina Familiar y Comunitaria, EAP Vía Barcino. Miembro del grupo de asma de la Societat Catalana de Medicina Familiar i Comunitària. Profesor asociado, Facultad de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain. e Diplomadas en Enfermería, EAP Chafarinas, Barcelona, Spain. Correspondence: Montserrat Rodríguez Mas. C/ Torras i Bages, Cerdanyola del Vallès (Barcelona). España. montserodmas@hotmail.com Received 11 December Accepted for publication 21 May Aten Primaria 2003;32(5):

2 Introduction Although inhalation is the route of delivery of choice in the treatment of asthma, inhalers are often used incorrectly. 1-7 Many patients have received no instruction in inhalation technique (IT), and even many health care professionals do not know the correct steps Earlier studies have evaluated the skills of patients with asthma in the use of pressurized canister inhalers (PCI), but data on the use of other devices are scarce. Few studies of this type have been done in the primary care setting. Despite the publication of clinical practice guidelines, we suspect that IT is still often performed incorrectly. This led us to investigate our patients skills in performing the steps needed to use different inhalation systems, and the variables that can influence correct performance. Methods Study design Descriptive, cross-sectional study. Participating center An urban primary care center and primary care staff. Study group selection We included all patients aged 18 to 80 years and diagnosed as having asthma who were registered with the program at our center (n=281 patients). Inclusion criteria Seen for more than 1 year for asthma, and 1 or more prescriptions for inhaled medications during the preceding 2 years. PCI: 48.9% (n=23) Correct technique: 46.1% (n=65) PCI+spacer: 40.9% (n=27) Candidates: 281 patients with asthma Included: 141 patients with asthma Turbuhaler 61.5% (n=32) Exclusion criteria Declining to participate in the study, missing an appointment or not locatable, problems traveling to the center, incapacitating neurological or psychiatric disorders, terminal neoplasm, or advanced AIDS. We reviewed the clinical history of all patients to record the following variables: sex, age, educational level, year of diagnosis, classification of asthma according to the GINA 98 system, 16 treatment, inhalation system used, and physician responsible for the patient. With the doctor s or nurse s permission, each participant was contacted by telephone (up to four attempts) at different times of day to schedule an individual appointment for an IT test. If no phone number was recorded, we went to the patient s home. On the basis of these inclusion and exclusion criteria, a total of 141 patients were recruited to investigate IT. Description of the IT evaluation test Each patient was asked to demonstrate how they used their inhaler; no information was provided prior to the test. Each step in the process was checked in accordance with SEPAR-semFYC guidelines. 12,13 For scoring purposes the technique was broken down into several steps; for each step performed correctly, 1 point was scored. The technique was considered incorrect when the total score was >9. For patients who used more than one inhaler system, the results were analyzed separately for each device. If one of the techniques was performed incorrectly, the patient s IT was considered incorrect. Outcome measures Main outcome variable: percentage of patients with correct IT. We analyzed the percentage of patients with correct IT for each inhalation system separately, and for all systems globally. The Review of IT Accuhaler 62,5% (n=10) Excluded: 140 (declined to participate in the study, age <18 or >80 years, not locatable, problems traveling for appointments, incapacitating neurological alteration or psychiatric disorder, terminal neoplasm, advanced AIDS, incorrect use of medication PCI: 51,06% (n=24) Incorrect technique: 53.9% (n=76) PCI+spacer: 59.1% (n=39) Turbuhaler 38,5% (n=20) Accuhaler: 37,5% (n=6) Because some patients used more than one inhalation system, the total number of techniques analyzed was 185. Not included in the scheme are 4 patients who used dry powder inhalers. PCI indicates pressurized canister inhaler. Variables analyzed: percentage of errors for each step and each system, and factors that can influence the correct performance of the IT (age, sex, educational level, number and type and type of systems used, severity of asthma, number of crises per year, physician responsible for follow-up, number of visits to the center for asthma, time since diagnosis, and mean FEM and FEV). Esquema general del estudio Are our patients with asthma still using inhalers incorrectly? Material and methods 270 Aten Primaria 2003;32(5):269-75

3 TABLE 1 Use of inhalation systems, percentage of errors and correct inhalation technique Inhalation system* N(%) Correct technique (CT) Incorrect technique PCI 47 (33.3) 48.9% (n=23) 51.06% (n=24) PCI+spacer 66 (46.8) 40.9% (n=27) 59.1% (n=39) Turbuhaler 52 (36.8) 61.5% (n=32) 38.5% (n=20) Accuhaler 16 (11.3) 62.5% (n=10) 37.5% (n=6) Metered dose dry powder 4 (2.8) 25% (n=1) 75% (n=3) *Because no patients used an Autohaler device, this system was not evaluated here. percentage error rates were compared for each step and for each system. As secondary variables we analyzed factors that could influence IT performance. Statistical analysis Ninety-five percent confidence intervals for the percentage error rates were calculated, and bivariate analysis was done with comparison of the means (Student s t test) and comparison of the proportions (χ 2 ). All analyses were done with version 10.0 of the SPSS. Results Of the 141 patients, 77.3% (n=109) were women, and mean age was (SD, 18.0) years. The different inhalation systems used by our patients are shown in Table 1. About three-fourths of the patients (73.8%) used only one inhalation device (n=104), 21.3% (n=30) used two systems, and 5% (n=7) used three, thus the total number of inhalation systems we checked in this study was 185. When the only device used was a PCI, the active principle was a short-acting β 2 in 90% of the prescriptions. When more than one system was used, a PCI was one of the devices used by most patients. Overall, IT was incorrect in 53.9% (n=76) of the patients. The Accuhaler and Turbuhaler systems yielded the highest scores (correct IT in 62.5% and 61.5% of the patients, respectively). The system that yielded the highest percentage of errors (59.1%) was PCI+spacer (Table 1). The steps with the highest percentage error rates for all inhalation systems are shown in Table 2. Younger patients and patients with a higher educational level more TABLE 2 Percentage of errors in each system and step PCI PCI+spacer Turbuhaler Accuhaler Single-dose dry powder General Stand or sit upright 0% 0% 1.92% 0% 0% 0.5% (n=1) (n=1) Remove cap 0% 0% 1.92% 6.25% 0% 1.08% (n=1) (n=1) (n=2) Shake a /Slide lever b /Load inhaler c 10.64% 15.15% 9.62% 6.25% 75% 12.97% (n=5) (n=10) (n=5) (n=1) (n=3) (n=24) Connect inhaler to the spacer/hold inhaler upright 10.64% 13.64% 1.92% * 0% 8.8% (n=5) (n=9) (n=1) (n=15) Exhale all the way 59.57% 69.70% 59.62% 56.25% 100% 63.78% (n=28) (n=46) (n=31) (n=9) (n=4) (n=118) Close lips around mouthpiece 21.28% 19.70% 7.69% ) 6.25% 50% 16.21% (n=10) (n=13) (n=4 (n=1) (n=2) (n=30) Breath in slowly 59.57% 56.06% 32.69% 12.5% 50% 46.48% (n=28) (n=37) (n=17) (n=2) (n=2) (n=86) Remove from mouth 25.53% 53.03% * * * 41.59% (n=12) (n=35) (n=47) Hold breath 65.96% 75.76% 55.77% 50% 100% 65.94% (n=31) (n=50) (n=29) (n=8) (n=4) (n=122) Breath out slowly 70.21% 65.15% 59.62% 56.25% 100% 64.86% (n=33) (n=43) (n=31) (n=9) (n=4) (n=120) Wait at least 30 s between puffs 51.06% 65.15% 55.77% 75% * 59.66% (n=24) (n=43) (n=29) (n=12) (n=108) Replace cap 14.89% 21.21% 11.53% 12.5% 25% 16.21% (n=7) (n=14) (n=6) (n=2) (n=1) (n=30) Rinse mouth 51.06% 60.61% 51.92% 37.5% 50% 53.51% (n=24) (n=40) (n=27) (n=6) (n=2) (n=99) *Steps not used in these systems according to SEPAR-semFYC guidelines. a Step used specifically for PCI and PCI+spacer systems. b Step used specifically for the Accuhaler system. c Step analyzed for the Turbohaler system (two twists) and single-dose dry powder system (perforate capsule). 12.5% of the patients who used an Accuhaler (n=2) and 32.69% of those who used a Turbuhaler (n=17) did not know how to tell when the inhaler was empty. Aten Primaria 2003;32(5):

4 frequently used inhalation systems correctly (P=.007) (Table 3). Mean age of the patients who used different systems was: Turbuhaler, 42.5 (±18.82) years; Accuhaler, (±2.87); PCI, (±21.21; PCI+spacer, (±14.63), and dry powder inhaler, 41. The percentage of patients who had received university-level education, by inhalation system, was Turbuhaler, 36.5%; Accuhaler, 18.8%; PCI, 14.9%, and PCI+spacer, 7.6%. There were no statistically significant differences in the percentage rates of correct IT and any of the other variables shown in table 3 (P>.05). Discussion Studies of the prevalence of asthma indicate that 1% to 5% of the population have this disease. 14,17 In our study, 1.8% of the population had asthma. The higher percentage of asthma in women may reflect their greater use of health care services. Underrecording was found for both the prevalence and classification of asthma. This finding may reflect the fact that health care staff are less aware of this disease than they are of others. As reported in an earlier study, 3 a large percentage of our patients used their PCI without a spacer. The fact that most patients used shortacting β 2 on an as-needed basis may account for this finding. Patients who were taking different medications via a PCI used a spacer, as recommended by current guidelines Use of a single inhalation system is advisable to favor compliance with instructions for IT. 18 In the present study we found that IT was worse in patients who used more than one inhaler. The number of errors was proportional to the number of devices used, although this relationship was not statistically significant. As in other studies, the percentage of patients with incorrect IT was high. 1-5,9-11 The similarities in error rates may TABLE 3 Analysis of the variables that can influence correct inhalation technique Variables Correct technique Incorrect technique P Sex Men 53% 47% >.05 Women 44% 56% Mean age, years 51.4± ± Mean number of years since diagnosis 12.1 (CI, ) 10.7 (CI, ) >.05 Mean number of visits to the PCC per year 2.6 (CI, ) 2.57 (CI, ) >.05 Mean number of crises per year 0.78 (CI, ).97 (CI, ) >.05 Mean FEV (CI, ) (CI, ) >.05 Mean FEM (CI, ) (CI, ) >.05 Patients followed by a family physician 42.9% 57.1% >.05 Patients followed by a family physician and a specialist 53.1% 46.9% >.05 Level of education.007 Illiterate 35.6% 64.4% Primary 42.6% 57.4% Higher 71.4% 28.6% Classification of asthma >.05 Intermittent 33.3% 66.6% Persistent mild 62.5% 37.5% Persistent moderate 59.1% 40.9% Persistent severe - 100% Not recorded 43.2% 56.8% Number of inhalation systems used >.05 One 47.1% 52.9% Two 43.3% 56.7% Three 42.9% 57.1% CI indicates 95% confidence interval; PCC, primary care center. 272 Aten Primaria 2003;32(5):269-75

5 Discussion Key points What is known about the subjec Drug delivery by inhalation is the route of choice for asthma, and incorrect use of inhalers seriously compromises the therapeutic effects of treatment and makes control of symptoms difficult. A large percentage of patients have never been taught correct inhalation techniques. A large percentage of patients perform inhalation techniques incorrectly. What this study contributes A large percentage of patients continue to perform inhalation techniques incorrectly despite the availability of many guidelines on asthma management. The only variables found to be related with correct inhalation techniques were age and level of education. We cannot conclude that any one inhalation device is superior to others. Exhaling completely before inhalation, holding the breath after inhalation, and breathing out slowly after inhalation were the steps with the highest percentage error rates. reflect inadequacies in the instructions patients receive. 3 As in other published studies, the steps that were most frequently performed incorrectly were exhaling completely before inhaling the dose 1-3 and holding the breath after inhalation. 1,2,4 Patients who used a Turbuhaler made fewer mistakes. When we analyzed the relationship between mean age and level of education and the inhalation system used, we found these variables to be confounders in our attempt to identify the best inhalation system: the system that appeared to be the best (Turbuhaler) was used predominantly by younger patients with a higher level of education. To offset the influence of these confounders we stratified the results by age group and re-examined the results to identify which inhalation system was used best in each subgroup. In both age subgroups (i.e., in patients older than and younger than 65 years), the inhalation devices that were used correctly most often were Turbuhalers and Accuhalers, although the difference in comparison to other systems was not statistically significant (probably because of the small sample size). Our findings suggest that the Turbuhaler device is superior to the rest. However, to confirm this, patients would need to be selected in a manner that ensured a homogeneous distribution, in terms of age and level of education, of participants who use different inhalation devices. Our results also suggest that when a specific inhalation system is singled out for analysis, each case should be dealt with individually according to the subject s characteristics. 4,13,14 As in other studies, the variables that were most clearly related with correct IT were age 4 and level of education. 3 In conclusion, we note a large percentage of our patients with asthma had errors in their inhalation technique. Health education efforts to teach patients how to use different inhalation devices correctly should be stepped up. Our study does not allow us to conclude that any one inhalation device is superior to the others. Future research will compare IT performance with different inhalation devices, taking into account the confounding factors identified above. We will also evaluate whether educational group workshops are effective in improving inhalation technique. References 1. Comella A, Serra J. Problemática en la utilización de los broncodilatadores en aerosol. Enfermería Científica 1987;69: Agustí AGN, Usseti P, Roca J, Montserrat JM, Rodríguez Roisín R, Agustí-Vidal A. Asma bronquial y broncodilatadores en aerosol: empleo incorrecto en nuestro medio. Med Clin (Barc) 1983;81: Benito Ortiz L, Pérez Sánchez FC, Nieto Sánchez MP, Sáiz Monzón ML, Crespo Fidalgo P, Aldecoa Álvarez-Santullano C. Estudio sobre el empleo de broncodilatadores inhalados por los pacientes de atención primaria. Aten Primaria 1996;18: Carrión Valero F, Maya Martínez M, Fontana Sanchis I, Díaz López J, Marín Pardo J. Técnica de inhalación en los pacientes con enfermedades respiratorias crónicas. Arch Bronconeumol 2000;36: Orehek J, Gayrard P, Grimaud CH, Charpin J. Patient error in use of bronchodilator metered aerosols. Br Med J 1976;1: Ascunce Saldaña P, Gallego Fernández C, López del Carre P, Ferrándiz Gosalvez SR. Empleo de los inhaladores. Importancia de la educación al paciente. Farm Clin 1987;4: Hueto J, Borderias L, Eguia VM, González-Moya JE, Colomo A, Vidal MJ, et al. Evaluación del uso de los inhaladores. Importancia de su correcta instrucción. Arch Bronconeumol 1990; 26: Madueño Caro AJ, Martín Olmedo PJ, García Martí E, Benítez Rodríguez E. Evaluación del conocimiento teórico-práctico de los sistemas de inhalación en médicos de atención primaria, posgrados en formación y pregrado. Aten Primaria 2000;25: Félez MA, González Clemente JM, Cardona Q, Montserrat JM, Picado C. Destreza en el manejo de los aerosoles por parte del personal sanitario. Rev Clin Esp 1991;188: Hanania NA, Wittman R, Kesten S, Chapman KR. Medical personnel s knowledge of and hability to use inhaling devices. Chest 1994;105: Aten Primaria 2003;32(5):

6 11. Plaza V, Giner J, Gómez J, Casan P, Sanchis J. Conocimientos y destreza en el manejo del inhalador Turbuhaler por parte del personal sanitario. Arch Bronconeumol 1997;33: Giner J, Basualdo LV, Casan P, Hernández C, Macián V, Martínez I, et al. Normativa sobre la utilización de fármacos inhalados. Arch Bronconeumol 2000;36: Naberan Toña K, Calvo Corbella E, García Bunell L, Hernández Huet E, Jorge Barreiro F, Llauger Rosselló MA, et al. Manejo del asma en Atención Primaria. Barcelona: Recomendaciones de la semfyc, Flor Escriche X, Mas Pujol M, Llauger Rosselló MA, Hernández Huet E, García Arranz T, Nualart Feliu M, et al. Asma bronquial. Jano 2001;60: Flor Escriche X, García Arranz T, Juvanteny Gorgals J, Llauger Rosselló MA, Mas Pujol M, Moretó Reventós A, et al. Educación sanitaria en asma. 1.ª ed. Barcelona: semfyc, Global iniciative for asthma. Pocket Guide for asthma manegement and prevention. Reided National Institute of Health. National Heart, Lung and Blood Institute. NIH. Publication Nº b, November Soriano JB, Antó JM. Epidemiología del asma en España. En: Sanchís J, Casan P, editores. Avances en asma. Barcelona: Prous Science 1999; p Van der Palen J, Klein JJ, Van Herwaarden CL, Zielhuis GA, Seydel ER. Multiple inhalers confuse asthma patients. Eur Respir J 1999;14: COMMENTARY How to Improve Inhalation Technique in Our Patients With Asthma F. Deulofeu i Fontanillas Cap de Servei Medicina Interna, Fundació Hospital de Sant Celoni, Barcelona, Spain. Drug delivery by inhalation to administer bronchodilators and antiinflammatory medication has contributed significantly to improvements in care for patients with asthma. Inhalation therapy has been known and used for about 4000 years, 1 although it was not until 1829 that the first device for producing particle suspensions was developed. 2 In subsequent years a number of systems were perfected, and the first pressurized canister system was marketed in Spacers first appeared in the 1970s, and dry powder inhalers made their appearance soon after. 3 Inhalation devices have made it possible to deliver very small doses of drugs directly to the target organ, thus achieving rapid, effective action with a minimum of side effects. Thanks to these systems, asthma can be controlled with highly effective treatments and minimal side effects, and patients can lead a completely normal life. As shown in a number of studies 4-6 and confirmed in this issue by Flor Escriche et al, patients use inhalation systems incorrectly, and this probably diminishes the efficacy of treatment. The authors found that 53.9% of their patients performed inhalation techniques incorrectly, the steps with the highest percentage error rates were exhaling completely before inhaling the dose, holding the breath after inhaling, and exhaling slowly afterwards. Since the appearance of pressurized canisters, many other systems have appeared that aim to facilitate compliance with treatment, and that have been shown to increase the Key points Slightly more than half of all patients with asthma were found not to use their inhalers correctly. This problem can be solved through health education. Continuing quality improvement plans are the only measure likely to solve problems that arise in daily practice. amount of drug that reaches the lungs. But this variety of products, each of which requires a different technique for correct use, confuses our patients and make compliance difficult. Flor Escriche et al document this in their study; moreover, they note that at any given time a patient may be using two or three different inhalation devices. How can we improve our patients inhalation technique? Do the kinds of errors in technique identified thus far have a clinically significant effect on the control of asthma? As I understand the issue, these are the questions that need to be answered, and the lines of research that could be undertaken: 274 Aten Primaria 2003;32(5):269-75

7 To improve inhalation techniques, health education is needed both for health care professionals and for patients. Workshops should train health care professionals in the techniques used for different devices, the advantages of each, and in how to choose the most appropriate type of inhaler for different patients. These workshops should be held periodically; training the trainers is fundamental. As for the patients, their inhalation technique should be checked when they come to the health center, and errors in technique should be corrected. It is also important to use only one inhalation device for each patient. Continuing quality improvement is based on a cycle consisting of several stages. First the problem must be detected (incorrect inhalation technique), then its possible causes analyzed (inadequate information about the correct technique, use of different devices, etc.). The next step is to plan corrective measures (workshops for professionals, checking inhalation technique at each visit, etc.), and this should be followed by further studies to determine whether the problem has been dealt with effectively. With the technology currently available, health care professionals have access to a great deal of information in the form of guidelines, protocols, scientific journals, and other sources that help us to keep our knowledge up to date. These resources also help us to make the best diagnostic and therapeutic decisions for our patients. Articles such as that by Flor Escriche et al warn us that the recommendations in guidelines are not always followed. Therefore we should examine the possibility of incorporating in our daily work processes a system of practice audits as part of a continuing quality improvement program. References 1. Álvarez Sala JL. Evolución de la terapéutica broncodilatadora. Jano 1997;52: Giner J, Calpena M, Sáiz L, Blanch A. Sistemas de administración de fármacos por vía inhalatoria. Rev Rol Enfermería 1997; 224: Grossman J. The evolution of inhaler technology. J Asthma 1994;31: Agustí AGN, Usseti P, Roca J, Montserrat JM, Rodríguez Roisín R, Agustí-Vidal A. Asma bronquial y broncodilatadores en aerosol: empleo incorrecto en nuestro medio. Med Clin (Barc) 1983;81: Carrión Valero F, Maya Martínez M, Fontana Sanchís I, Díaz López J, Marín Pardo J. Técnica de inhalación en los pacientes con enfermedades respiratorias crónicas. Arch Bronconeumol 2000;36: Madueño Caro AJ, Martín Olmedo PJ, García Martí E, Benítez Rodríguez E. Evaluación del conocimiento teórico-práctico de los sistemas de inhalación en médicos de atención primaria, posgrados en formación y pregrado. Aten Primaria 2000;25: Aten Primaria 2003;32(5):