Randomized trial of physiotherapy and hypertonic saline techniques for sputum induction in asthmatic children and adolescents

Egberto Luiz Felicio-Júnior Viviani Barnabé Francine Maria de Almeida Monise Dematte Avona Isabella Santos de Genaro Adriana Kurdejak Miriam Cardoso Neves Eller Karina Pierantozzi Verganid Joaquim Carlos Rodrigues Iolanda de Fátima Lopes Calvo Tibério Milton de Arruda Martins Beatriz Mangueira Saraiva-Romanholo About the authors

Abstract

OBJECTIVES:

This study aimed to analyze the efficiency of physiotherapy techniques in sputum induction and in the evaluation of pulmonary inflammation in asthmatic children and adolescents. Although hypertonic saline (HS) is widely used for sputum induction (SI), specific techniques and maneuvers of physiotherapy (P) may facilitate the collection of mucus in some asthmatic children and adolescents.

METHODS:

A randomized crossover study was performed in patients with well-controlled asthma, and 90 sputum samples were collected. Children and adolescents were assessed using spirometry and randomized at entry into one of three sputum induction techniques: (i) 3% hypertonic saline – HS technique; (ii) physiotherapy (oscillatory positive expiratory pressure, forced expiration, and acceleration of expiratory flow) – P technique; and (iii) hypertonic saline + physiotherapy – HSP technique. ClinicalTrials.gov: NCT03136042.

RESULTS:

The total cells (mL) and the percentage (%) of differential inflammatory cells were similar in all techniques. The sputum weight (g) in the HSP technique was significantly higher than that in the HS technique. In all techniques, the percentage of viable cells was >50%, and there was no difference between the HS and P techniques. Moreover, sputum induction did not cause any alterations in the pulmonary function of patients.

CONCLUSION:

The physiotherapy sputum collection technique was effective in obtaining viable cells from mucus samples and yielded the same amount of sputum as the gold standard technique (hypertonic saline). In addition, the physiotherapy maneuvers were both safe and useful for sputum induction in asthmatic children and adolescents with well-controlled asthma.

Asthma; Children; Hypertonic Saline Solution; Sputum Induction; Physical Therapy Techniques


INTRODUCTION

Asthma is a chronic respiratory disease that affects 1% to 18% of the population in different countries (11. GINA. Global Initiative for Asthma - Global Strategy for Asthma Management and Prevention NHLBI/WHO Workshop Report 2017. Available from: http://www.ginasthma.org
http://www.ginasthma.org...
). In Brazil, asthma is one of the respiratory diseases with the highest mortality rates (five deaths per day) and is the reason for >120,000 hospitalizations per year (22. Cardoso TA, Roncada C, Silva ERD, Pinto LA, Jones MH, Stein RT, et al. The impact of asthma in Brazil: a longitudinal analysis of data from a Brazilian national database system. J Bras Pneumol. 2017;43(3):163-8. https://doi.org/10.1590/s1806-37562016000000352.
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).

The principal triggers of asthma include viral infections, environmental or occupational allergens, smoking, exercise, and stress (33. Brigham EP, West NE. Diagnosis of asthma: diagnostic testing. Int Forum Allergy Rhinol. 2015;5 Suppl 1:S27-30. https://doi.org/10.1002/alr.21597.
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). Asthma exacerbations are characterized by airway obstruction, inflammation, and airway hyper-responsiveness (44. Navanandan N, Federico M, Mistry RD. Positive Expiratory Pressure for the Treatment of Acute Asthma Exacerbations: A Randomized Controlled Trial. J Pediatr. 2017;185:149-154.e2. https://doi.org/10.1016/j.jpeds.2017.02.032.
https://doi.org/10.1016/j.jpeds.2017.02....
). Although asthma is mainly diagnosed on the basis of clinical findings, a pulmonary function test needs to be performed to confirm airway obstruction, particularly in adolescents and adults (55. GINA. Global Initiative for Asthma - Global Strategy for Asthma Management and Prevention NHLBI/WHO Workshop Report 2019 2019. Available from: http://www.ginasthma.org
http://www.ginasthma.org...
). Asthma control includes the evaluation of symptoms and their reduction or resolution after treatment (55. GINA. Global Initiative for Asthma - Global Strategy for Asthma Management and Prevention NHLBI/WHO Workshop Report 2019 2019. Available from: http://www.ginasthma.org
http://www.ginasthma.org...
). To achieve these goals, inflammation must be controlled and the disease phenotype must be identified. With respect to the evaluation of this condition, sputum induction is a perfectly feasible diagnostic test (66. Bush A. Pathophysiological Mechanisms of Asthma. Front Pediatr. 2019;7:68. https://doi.org/10.3389/fped.2019.00068.
https://doi.org/10.3389/fped.2019.00068...
) and sputum cell counts reflect the underlying disease and treatment adherence (66. Bush A. Pathophysiological Mechanisms of Asthma. Front Pediatr. 2019;7:68. https://doi.org/10.3389/fped.2019.00068.
https://doi.org/10.3389/fped.2019.00068...
).

After the age of 6 years, the use of hypertonic saline to induce sputum is employed for cytology analysis, and this noninvasive technique allows for the assessment of inflammatory cells such as eosinophils and neutrophils (77. Pijnenburg MW, Baraldi E, Brand PL, Carlsen KH, Eber E, Frischer T, et al. Monitoring asthma in children. Eur Respir J. 2015;45(4):906-25. https://doi.org/10.1183/09031936.00088814.
https://doi.org/10.1183/09031936.0008881...
).

Researchers sometimes encounter difficulties in obtaining induced sputum in stable patients, and respiratory therapy can promote mucus clearance through specific techniques and maneuvers. The wide variety of techniques for sputum induction and expectoration include huffing, oscillatory positive expiratory pressure (OPEP) therapy, forced expiratory technique (FET) (88. McCool FD, Rosen MJ. Nonpharmacologic airway clearance therapies: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1 Suppl):250S-9S. https://doi.org/10.1378/chest.129.1_suppl.250S.
https://doi.org/10.1378/chest.129.1_supp...

9. Morsch AL, Amorim MM, Barbieri A, Santoro LL, Fernandes AL. Influence of oscillating positive expiratory pressure and the forced expiratory technique on sputum cell counts and quantity of induced sputum in patients with asthma or chronic obstructive pulmonary disease. J Bras Pneumol. 2008;34(12):1026-32. https://doi.org/10.1590/S1806-37132008001200007.
https://doi.org/10.1590/S1806-3713200800...
-1010. Flude LJ, Agent P, Bilton D. Chest physiotherapy techniques in bronchiectasis. Clin Chest Med. 2012;33(2):351-61. https://doi.org/10.1016/j.ccm.2012.02.009.
https://doi.org/10.1016/j.ccm.2012.02.00...
), and others (1111. Bott J, Blumenthal S, Buxton M, Ellum S, Falconer C, Garrod R, et al. Guidelines for the physiotherapy management of the adult, medical, spontaneously breathing patient. Thorax. 2009;64 Suppl 1:i1-51. https://doi.org/10.1136/thx.2008.110726.
https://doi.org/10.1136/thx.2008.110726...
). The OPEP apparatus reduces the viscoelasticity of bronchial secretions (1212. Lee AL, Williamson HC, Lorensini S, Spencer LM. The effects of oscillating positive expiratory pressure therapy in adults with stable non-cystic fibrosis bronchiectasis: A systematic review. Chron Respir Dis. 2015;12(1):36-46. https://doi.org/10.1177/1479972314562407.
https://doi.org/10.1177/1479972314562407...
), and some studies have shown that physiotherapy maneuvers are safe and have a satisfactory effect on sputum induction in patients with respiratory diseases (1313. Warnock L, Gates A. Chest physiotherapy compared to no chest physiotherapy for cystic fibrosis. Cochrane Database Syst Rev. 2015;(12):CD001401. https://doi.org/10.1002/14651858.CD001401.pub3.
https://doi.org/10.1002/14651858.CD00140...
,1414. Lima LH, Lopes MV, Falcao RT, Freitas RM, Oliveira TF, da Costa Mda C. Intervention for ineffective airway clearance in asthmatic children: a controlled and randomized clinical trial. Int J Nurs Pract. 2013;19(1):88-94. https://doi.org/10.1111/ijn.12033.
https://doi.org/10.1111/ijn.12033...
). This study aimed to compare three different techniques of sputum induction in children with asthma and to evaluate the effectiveness of collecting induced sputum through physiotherapy maneuvers.

METHODS

This study was approved by the Institutional Ethics Committee of the Clinical Hospital of the School of Medicine of University of Sao Paulo (protocol no. 674.125) and registered in ClinicalTrials.gov (NCT03136042). Thirty-eight asthmatic children and adolescents were recruited from the Pediatric Pneumology Outpatient Clinic of the Children’s Institute of the Clinical Hospital (University of Sao Paulo) and were asked to sign an informed consent form. The children and adolescents were between the ages of 7 and 18 years and were classified as having well-controlled asthma, according to the Global Initiative for Asthma 2017 (55. GINA. Global Initiative for Asthma - Global Strategy for Asthma Management and Prevention NHLBI/WHO Workshop Report 2019 2019. Available from: http://www.ginasthma.org
http://www.ginasthma.org...
). Patients using inhaled steroids in combination with long-acting beta2-agonists were also included. Patients diagnosed with other chronic pulmonary diseases (e.g., cystic fibrosis, ciliary dyskinesia, bronchiolitis obliterans, and bronchopulmonary dysplasia), those who were unable to perform pulmonary function tests, and those with insufficient sputum samples were excluded.

The primary aim of the study was to evaluate whether physiotherapy techniques, such as OPEP therapy, huffing, and acceleration of expiratory flow, are safe and efficient for sputum induction in children and adolescents with well-controlled asthma.

The secondary aim was to evaluate whether samples collected using 3% hypertonic saline and physiotherapy techniques are of good quality according to the acceptance criteria.

Study design

After the participants were recruited and the informed consent form was signed, the first visit was scheduled. Thereafter, a blinded investigator randomized each participant into one of three crossover techniques as the first sputum induction protocol. The sequence of the subsequent techniques performed was as follows: (i) hypertonic saline (3%) - HS technique; (ii) physiotherapy (OPEP therapy, forced expiration, and acceleration of expiratory flow) - P technique; and (iii) hypertonic saline + physiotherapy - HSP technique. Each patient made three visits for sputum induction using each technique, with 7-day intervals to avoid interference with the results obtained with each induction (Figure 1).

Figure 1
Study design. Cross-over techniques of induced sputum collection. HS: hypertonic saline; P: physiotherapy; HSP: hypertonic saline + physiotherapy.

Thirty-three asthmatic children and adolescents of both sexes participated in the study, and 99 samples of induced sputum were collected (Figure 1). Three children were excluded because the collected sputum samples were <2.0 mL, which was considered inadequate according to the criteria for sample acceptance (1515. Saraiva-Romanholo BM, Barnabé V, Carvalho AL, Martins MA, Saldiva PH, Nunes Mdo P. Comparison of three methods for differential cell count in induced sputum. Chest. 2003;124(3):1060-6. https://doi.org/10.1378/chest.124.3.1060.
https://doi.org/10.1378/chest.124.3.1060...
).

Pulmonary function

Spirometry was performed before and after the inhalation of 200 µg salbutamol (bronchodilator), in accordance with the American Thoracic Society guidelines (1616. [No authors listed]. Standardization of Spirometry,1994 Update. American Thoracic Society. Am J Respir Crit Care Med. 1995;152(3):1107-36. https://doi.org/10.1164/ajrccm.152.3.7663792.
https://doi.org/10.1164/ajrccm.152.3.766...
), using a KoKo spirometer (PDS Instrumentation Inc., Louisville, KY, USA). If the patients did not experience respiratory discomfort or did not have a >20% decrease in pulmonary function, sputum induction was performed with one of the techniques and spirometry was repeated.

The values of forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), and forced vital capacity (FVC) expelled in the first second of a forced expiration (FEV1/FVC) were evaluated before and after bronchodilator administration and after performing the sputum induction techniques (1717. Eller MCN, Vergani KP, Saraiva-Romanholo BM, Antonangelo L, Leone C, Rodrigues JC. Can inflammatory markers in induced sputum be used to detect phenotypes and endotypes of pediatric severe therapy-resistant asthma? Pediatr Pulmonol. 2018;53(9):1208-17. https://doi.org/10.1002/ppul.24075.
https://doi.org/10.1002/ppul.24075...
).

Sputum induction

After spirometry, we collected induced sputum samples using the three techniques in all children and adolescents, as detailed below.

(i) Sputum induction with 3% hypertonic saline (HS technique): Children and adolescents received a nebulization with hypertonic saline at a concentration of 3% for 7 min. The aerosol was generated by an ultrasonic nebulizer (Ultraneb 99; DeVilbiss, Somerset, PA, USA) with an output of 2.4 mL/min and a mass median aerodynamic diameter of 4.5 µm. If the sputum sample volume was insufficient, the nebulization could be repeated three times. After each nebulization, pulmonary function was monitored by obtaining the PEF values using the Koko spirometer. If hypertonic saline did not induce a PEF decrease (≥20%), the next nebulization was performed (1717. Eller MCN, Vergani KP, Saraiva-Romanholo BM, Antonangelo L, Leone C, Rodrigues JC. Can inflammatory markers in induced sputum be used to detect phenotypes and endotypes of pediatric severe therapy-resistant asthma? Pediatr Pulmonol. 2018;53(9):1208-17. https://doi.org/10.1002/ppul.24075.
https://doi.org/10.1002/ppul.24075...
,1818. Toledo MF, Saraiva-Romanholo BM, Oliveira RC, da Silva LF, Solé D. Air pollution and its relationship to lung function among adolescents from Taubate, São Paulo, Brazil. Allergol Immunopathol. 2018;46(2):160-6. https://doi.org/10.1016/j.aller.2017.04.007.
https://doi.org/10.1016/j.aller.2017.04....
).

(ii) Sputum induction through physiotherapy maneuvers (P technique): The patients’ thorax was inclined by 45° in a seated position. The patients were instructed to perform calm and long exhalations through repeated OPEP therapy with a Flutter® device (Scandipharm, Birmingham, AL, USA), continuously for a duration of 5 min. Thereafter, the children and adolescents were placed in a supine 0° position (Figure 2) and underwent another 5 min of FET with an open mouth/glottis (FET/huffing) in conjunction with acceleration of expiratory flow. This technique was applied by a single physiotherapist, who positioned one hand on the patient’s xiphoid process and placed the other hand on the manubrium of the patient’s sternum (Figure 3) (99. Morsch AL, Amorim MM, Barbieri A, Santoro LL, Fernandes AL. Influence of oscillating positive expiratory pressure and the forced expiratory technique on sputum cell counts and quantity of induced sputum in patients with asthma or chronic obstructive pulmonary disease. J Bras Pneumol. 2008;34(12):1026-32. https://doi.org/10.1590/S1806-37132008001200007.
https://doi.org/10.1590/S1806-3713200800...
). At the end of the maneuvers, all patients were advised to effectively cough into a proper sterile container.

Figure 2
Illustrative image showing a patient performing oscillating positive expiratory pressure therapy for 5 min in a sitting position.

(iii) Sputum induction with 3% hypertonic saline associated with physiotherapy maneuvers (HSP technique): First, children and adolescents underwent sputum induction through one inhalation of 3% hypertonic saline for 7 min. Second, they underwent 5 min of OPEP therapy and 5 min of huffing/FET, as described above. Third, they were advised to effectively cough into a suitable sterile container.

Figure 3
Illustrative image demonstrating the forced expiration (huffing) technique associated with accelerated expiratory flow. The therapist places one hand on the patient’s manubrium and the other hand on the xiphoid process of the patient’s sternum. Thereafter, the therapist brings the two hands together during the patient’s exhalation, accelerating the outflow of air, while the patient simultaneously exhales with the glottis and mouth open, and the abdominal muscles contracted.

Sputum processing

All samples were processed according to the previously published protocol (1818. Toledo MF, Saraiva-Romanholo BM, Oliveira RC, da Silva LF, Solé D. Air pollution and its relationship to lung function among adolescents from Taubate, São Paulo, Brazil. Allergol Immunopathol. 2018;46(2):160-6. https://doi.org/10.1016/j.aller.2017.04.007.
https://doi.org/10.1016/j.aller.2017.04....
). Briefly, sputum was separated from saliva and placed into a Petri dish and weighed. The samples were treated with 0.1% dithiothreitol (Sigma-Aldrich, Sao Paulo, Brazil), gently vortexed, and placed in a shaking water bath at 37°C for 20 min to ensure adequate homogenization. This suspension was filtered through a 48-µm nylon gauze (BBSH Thompson, Scarborough, Ontario, Canada) to remove cell debris and remaining mucus. The resulting clear suspension of sputum was centrifuged at 790 × g for 10 min, and the supernatant was aspirated. The total cell count was determined using a hemocytometer (Neubauer chamber). Thereafter, cytospins were prepared using a Shandom III centrifuge (Shandom Southern Instruments, Sewickley, PA, USA). Differential cell counts of 300 cells per slide were obtained after Diff-Quick staining. A blinded researcher managed all measurements, and the criteria for acceptance of the sample were inhalation time between 5 and 20 min, sputum volume ≥2 mL, sample processing time <2h, squamous cells ≤80%, and at least 200 inflammatory cells per technique (1515. Saraiva-Romanholo BM, Barnabé V, Carvalho AL, Martins MA, Saldiva PH, Nunes Mdo P. Comparison of three methods for differential cell count in induced sputum. Chest. 2003;124(3):1060-6. https://doi.org/10.1378/chest.124.3.1060.
https://doi.org/10.1378/chest.124.3.1060...
).

Statistical analysis

Data were analyzed using repeated-measures analysis of variance, followed by a Tukey test (post hoc test). A p-value of <0.05 was considered significant. Data are presented as medians and interquartile ranges. Statistical analysis was performed with SigmaPlot version 12.0 software (Armonk, NY, USA).

RESULTS

Thirty-three asthmatic children and adolescents of both sexes (18 boys and 15 girls) participated in the study from January 2016 to July 2018. The average height was 1.44±0.18 m, and the average weight was 43.28±18.38 kg. Pulmonary function was evaluated both before and after salbutamol inhalation and after sputum induction. FEV1, PEF, and FEV1/FVC did not show any difference among the techniques (p≥0.05) (Table 1). None of the 33 asthmatic patients had any complications during or after the pulmonary function tests.

Table 1
Pulmonary function.

All sputum samples obtained using the P and HSP techniques were sufficient. In the HS technique, three children had an inadequate sputum volume and were excluded from the study in the first visit. During sputum induction with hypertonic saline, it was necessary to repeat the nebulization two times in 9 cases and three times in 10 cases; however, in most cases, only one nebulization was necessary.

The sputum induction time (Table 2) was higher with the HSP technique than with the other techniques (p=0.001). In all sputum samples, the percentage of viable cells was ≥80% (Table 2) and the HS technique presented higher values than the HSP technique (p=0.008). The sputum weight (Table 2) was higher with the HSP technique than with the HS technique (p=0.02). The total cell count and the percentage of differential cells (macrophages, neutrophils, lymphocytes, and eosinophils) were assessed, and the same inflammatory profile was observed among all three techniques (Table 2).

Table 2
Induced sputum characteristics.

DISCUSSION

This study compared the performance of three sputum induction methods: physiotherapy maneuvers (P technique), hypertonic saline (HS technique), and physiotherapy maneuvers plus hypertonic saline (HSP technique). Thirty-three children and adolescents participated in the study. In the HS technique, three children presented with an inadequate sputum volume and were excluded in the first visit. All sputum samples obtained using the P and HSP techniques were adequate and demonstrated good quality in accordance with the acceptance criteria. Pulmonary function was evaluated both before and after salbutamol inhalation and after sputum induction. No differences among the techniques were observed when FEV1, PEF, and FEV1/FVC were analyzed, with an increase in FEV1 after bronchodilator administration. Although the sputum weight was higher in the HSP technique, the pellet weight was higher in the P technique with the advantage of less time spent on sputum induction. Furthermore, the samples obtained through the P technique had a higher percentage of viable cells than those obtained through the HSP technique.

During sputum induction or after the end of the technique, there was no respiratory discomfort or limitation in any patient, corroborating the results obtained in adults with asthma (99. Morsch AL, Amorim MM, Barbieri A, Santoro LL, Fernandes AL. Influence of oscillating positive expiratory pressure and the forced expiratory technique on sputum cell counts and quantity of induced sputum in patients with asthma or chronic obstructive pulmonary disease. J Bras Pneumol. 2008;34(12):1026-32. https://doi.org/10.1590/S1806-37132008001200007.
https://doi.org/10.1590/S1806-3713200800...
). Physiotherapy can be offered to patients with benefits of potentially improving the disease condition, quality of life, cardiopulmonary fitness, and maximal inspiratory pressure, as well as reducing symptoms and medication use and improving airway clearance (1919. Bruurs ML, van der Giessen LJ, Moed H. The effectiveness of physiotherapy in patients with asthma: a systematic review of the literature. Respir Med. 2013;107(4):483-94. https://doi.org/10.1016/j.rmed.2012.12.017.
https://doi.org/10.1016/j.rmed.2012.12.0...
). Furthermore, all patients subjected to sputum induction through physiotherapy maneuvers yielded acceptable samples according to the criteria.

The main aim of our study was to demonstrate the efficiency of physiotherapy maneuvers in obtaining sputum samples for cell profile analysis from asthmatic children and adolescents. We observed that sputum induction with physiotherapy maneuvers (P and HSP techniques) was successful in all patients. A similar success was also reported in another study that showed the efficiency of physical or mechanical means of manipulating air flow in mobilizing secretions and producing sputum samples (1919. Bruurs ML, van der Giessen LJ, Moed H. The effectiveness of physiotherapy in patients with asthma: a systematic review of the literature. Respir Med. 2013;107(4):483-94. https://doi.org/10.1016/j.rmed.2012.12.017.
https://doi.org/10.1016/j.rmed.2012.12.0...
,2020. Tiddens HAWM, Rosenfeld M. Respiratory Manifestations. In: Taussig LM, Landau LI, editors. Pediatric Respiratory Medicine. 2nd ed. Philadelphia: Mosby; 2008. p. 871-87.). In addition, Morsch et al. (99. Morsch AL, Amorim MM, Barbieri A, Santoro LL, Fernandes AL. Influence of oscillating positive expiratory pressure and the forced expiratory technique on sputum cell counts and quantity of induced sputum in patients with asthma or chronic obstructive pulmonary disease. J Bras Pneumol. 2008;34(12):1026-32. https://doi.org/10.1590/S1806-37132008001200007.
https://doi.org/10.1590/S1806-3713200800...
) showed that the inclusion of physiotherapy maneuvers to obtain induced sputum contributed to increasing the final sputum sample weight in asthmatic patients. Further, it is important to emphasize that the sputum induction time with physiotherapy maneuvers was the same for all techniques used in this study. In addition, airway clearance techniques have been demonstrated to increase mucus transport and lung function (2020. Tiddens HAWM, Rosenfeld M. Respiratory Manifestations. In: Taussig LM, Landau LI, editors. Pediatric Respiratory Medicine. 2nd ed. Philadelphia: Mosby; 2008. p. 871-87.).

The fact that all patients who underwent sputum induction through physiotherapy maneuvers yielded adequate samples according to criteria indicate that these techniques of sputum recovery are both efficient and safe.

Meanwhile, when 3% hypertonic saline was used for sputum induction, we obtained a success rate of approximately 90%. Most likely, this high success rate with HS may be related to the fact that all patients had well-controlled asthma and these rates may be reduced in different clinical conditions. Palomino et al. (2121. Palomino AL, Bussamra MH, Saraiva-Romanholo BM, Martins MA, Nunes Mdo P, Rodrigues JC. [Induced sputum in children and adolescents with asthma: safety, clinical applicability and inflammatory cells aspects in stable patients and during exacerbation]. J Pediatr. 2005;81(3):216-24. https://doi.org/10.2223/1342.
https://doi.org/10.2223/1342...
) obtained a success rate of 67% in sputum induction in children with asthma. Other studies involving patients with different asthma severities achieved success rates of 56% (2222. Wilson NM, Bridge P, Spanevello A, Silverman M. Induced sputum in children: feasibility, repeatability, and relation of findings to asthma severity. Thorax. 2000;55(9):768-74. https://doi.org/10.1136/thorax.55.9.768.
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), 70% (1717. Eller MCN, Vergani KP, Saraiva-Romanholo BM, Antonangelo L, Leone C, Rodrigues JC. Can inflammatory markers in induced sputum be used to detect phenotypes and endotypes of pediatric severe therapy-resistant asthma? Pediatr Pulmonol. 2018;53(9):1208-17. https://doi.org/10.1002/ppul.24075.
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), 84% (2323. Cai Y, Carty K, Henry RL, Gibson PG. Persistence of sputum eosinophilia in children with controlled asthma when compared with healthy children. Eur Respir J. 1998;11(4):848-53. https://doi.org/10.1183/09031936.98.11040848.
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), and 95% (2424. Grootendorst DC, van den Bos JW, Romeijn JJ, Veselic-Charvat M, Duiverman EJ, Vrijlandt EJ, et al. Induced sputum in adolescents with severe stable asthma. Safety and the relationship of cell counts and eosinophil cationic protein to clinical severity. Eur Respir J. 1999;13(3):647-53. https://doi.org/10.1183/09031936.99.13364799.
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).

The amount of eosinophils and neutrophils in mucus is a good indicator of airway inflammation and may represent an important diagnosis and prognostic parameter (1717. Eller MCN, Vergani KP, Saraiva-Romanholo BM, Antonangelo L, Leone C, Rodrigues JC. Can inflammatory markers in induced sputum be used to detect phenotypes and endotypes of pediatric severe therapy-resistant asthma? Pediatr Pulmonol. 2018;53(9):1208-17. https://doi.org/10.1002/ppul.24075.
https://doi.org/10.1002/ppul.24075...
,2525. França-Pinto A, Mendes FA, de Carvalho-Pinto RM, Agondi RC, Cukier A, Stelmach R, et al. Aerobic training decreases bronchial hyperresponsiveness and systemic inflammation in patients with moderate or severe asthma: a randomised controlled trial. Thorax. 2015;70(8):732-9. https://doi.org/10.1136/thoraxjnl-2014-206070.
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). Induced sputum analysis is a safe method for assessing inflammatory markers in various diseases, such as controlled and uncontrolled asthma (2626. Barril S, Sebastián L, Cotta G, Crespo A, Mateus E, Torrejón M, et al. Utility of Induced Sputum in Routine Clinical Practice. Arch Bronconeumol. 2016;52(5):250-5. https://doi.org/10.1016/j.arbres.2015.10.002.
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), chronic obstructive pulmonary disease (2727. Fernandes L, Mesquita AM. The success and safety profile of sputum induction in patients with chronic obstructive pulmonary disease: An Indian experience. Indian J Tuberc. 2017;64(3):201-5. https://doi.org/10.1016/j.ijtb.2016.11.016.
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), and severe pneumonia in children (2828. DeLuca AN, Hammitt LL, Kim J, Higdon MM, Baggett HC, Brooks WA, et al. Safety of Induced Sputum Collection in Children Hospitalized With Severe or Very Severe Pneumonia. Clin Infect Dis. 2017;64(suppl_3):S301-S308. https://doi.org/10.1093/cid/cix078.
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).

With respect to the analysis of inflammatory markers in the three induction techniques, there were no significant differences in the percentages of eosinophils, neutrophils, macrophages, or lymphocytes, as the three techniques had the same inflammatory profiles. Physiotherapy maneuvers not only reduce infectious materials and inflammatory mediators from the airways but also decrease or even prevent host-mediated inflammatory tissue damage. This attenuates the mechanical consequences of obstructive secretions, such as hyperinflation, atelectasis, maldistribution of ventilation, ventilation/perfusion mismatch, and increased work of breathing. Physiotherapy maneuvers offer the most cost-effective therapy as well as a shorter time for procedure execution than other techniques (2929. Oberwaldner B. Physiotherapy for airway clearance in paediatrics. Eur Respir J. 2000;15(1):196-204. https://doi.org/10.1183/09031936.00.15119600.
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).

In our study, the physiotherapy maneuvers used were effective and could be responsible for the improvement in airway sputum expectoration. In addition to inflammatory cell recruitment, the physiotherapy maneuvers were able to recruit disrupted epithelial cells, which are also important in disease pathophysiology (3030. Gon Y, Hashimoto S. Role of airway epithelial barrier dysfunction in pathogenesis of asthma. Allergol Intern. 2018;67(1):12-7. https://doi.org/10.1016/j.alit.2017.08.011.
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-3232. Whitsett JA, Alenghat T. Respiratory epithelial cells orchestrate pulmonary innate immunity. Nat Immunol. 2015;16(1):27-35. https://doi.org/10.1038/ni.3045.
https://doi.org/10.1038/ni.3045...
). Although it seemed that the percentage of epithelial cells was increased in the physiotherapy group, no significant differences were observed among the groups. Additionally, it was previously described that <80% squamous cells are acceptable (3333. Fahy JV, Boushey HA, Lazarus SC, Mauger EA, Cherniack RM, Chinchilli VM, et al. Safety and reproducibility of sputum induction in asthmatic subjects in a multicenter study. Am J Respir Crit Care Med. 2001;163(6):1470-5. https://doi.org/10.1164/ajrccm.163.6.9901105.
https://doi.org/10.1164/ajrccm.163.6.990...
) and viable cells must be >50% (3434. Pizzichini E, Pizzichini MM, Efthimiadis A, Hargreave FE, Dolovich J. Measurement of inflammatory indices in induced sputum: effects of selection of sputum to minimize salivary contamination. Eur Respir J. 1996;9(6):1174-80. https://doi.org/10.1183/09031936.96.09061174.
https://doi.org/10.1183/09031936.96.0906...
) in the sputum samples.

We are also aware of the limitations of the study. The present study had a small sample size and randomization was applied only at study entry but not in the subsequent inductions. Further, we evaluated only the induction time and not the cost-benefit ratio among the techniques for sputum induction. It is important to compare the cost of acquiring the services of a health professional or a physiotherapist for sample collection, as well as the cost of the materials and equipment relevant for each technique. In addition, it would be important to evaluate the inflammatory markers in the supernatant of sputum samples to demonstrate the agreement among the different techniques.

Induction of sputum is considered a minimally invasive examination regardless of the technique used. Nevertheless, the safety of these techniques should be investigated with the application of questionnaires before and after each induction to evaluate the patients’ respiratory discomfort.

This study confirms that sputum induction through physiotherapy maneuvers is safe in asthmatic children and adolescents, and enables physical therapists to mobilize secretions without causing bronchospasm in patients. With the use of physiotherapy maneuvers, it is possible to induce sputum with the same quality as the gold standard technique (hypertonic saline) with no respiratory discomfort or limitations in asthmatic children and adolescents. Additionally, the cost-benefit ratio of the application of this technique is higher than that of the standard technique owing to the use of less materials and equipment.

CONCLUSION

The physiotherapy sputum collection technique was effective in obtaining viable cells in mucus samples and yielded the same amount of sputum as the gold standard technique (hypertonic saline). In addition, these physiotherapy maneuvers were both safe and useful for sputum induction in asthmatic children and adolescents with well-controlled asthma.

ACKNOWLEDGMENTS

This work was supported by the Sao Paulo Research Foundation (FAPESP) grant 2014/26829-4; Experimental Therapeutic Laboratory I (LIM 20), School of Medicine, University of Sao Paulo; School of Medicine Foundation (FFM/USP); and University Sao Paulo City (UNICID).

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Publication Dates

  • Publication in this collection
    24 Jan 2020
  • Date of issue
    2020

History

  • Received
    26 Aug 2019
  • Accepted
    19 Dec 2019
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