Success and safety of sputum induction in the clinical setting

Abstract

It has previously been reported that sputum induction is successful and safe in the clinical research setting. The authors examined the success and safety of sputum induction in routine clinical practice in patients with asthma or chronic airflow limitation of varying severity.Records of 304 patients with asthma and 25 with smoking related chronic airflow limitation were examined retrospectively. All had sputum induced as part of their routine clinical evaluation. When the baseline post salbutamol forced expiratory volume in one second (FEV1) was $70% predicted, the inductions consisted of inhalation of an aerosol of 3%, 4% and 5% saline, each given for 7 min. If the FEV1 was <70%, or there were other reasons for concern, the inductions were initiated with normal saline for shorter periods. Inhalations were discontinued when sputum was obtained or when there was a fall in FEV1 $20%. Success was identified by obtaining nonsquamous total and differential cell counts containing macrophages, and safety by the fall in FEV1.The overall success was 93%. The procedure was safe even amongst patients with an FEV1 of <60% and <1 L. Of 77 patients with an FEV1 between 40±59%, 8% fell by $20% and of 35 patients with an FEV1 <40%, 6% fell by 20%.Carefully standardized sputum induction can be successful and safe in patients with asthma or chronic airflow limitation in clinical practice, even when moderate or severe airflow limitation is present. Eur Respir J 2000; 16: 997±1000. Induced sputum examination has been increasingly used in the research of asthma and other airway conditions. Results have shown that sputum cell counts have a place in clinical practice [1±6] but, because an inhaled aerosol of hypertonic saline is a bronchoconstrictor stimulus [7,8], there have been concerns about the safety of sputum induction, particularly in patients with uncontrolled asthma or chronic airflow limitation. Safety has been addressed in three recent publications of research subjects with asthma, most of whom had a baseline forced expiratory volume in one second (FEV1) >60% [9±11]. In the present study, the success and safety of sputum induction in clinical practice in patients with asthma of varying severity and in patients with smoking related chronic airflow limitation was investigated. Additional safety precautions were taken and a large number of patients with an FEV1 <60% were included. Methods DesignThis was a retrospective analysis of 329 consecutive sputum inductions, performed as part of the clinical evaluation of patients with asthma or chronic airflow limitation who were attending the Firestone Regional Chest and Allergy Clinic between September 1, 1997 and March 31, 1998. PatientsThe patients with asthma had episodic symptoms of chest tightness, wheezing or dyspnoea plus a provocative concentration causing a 20% fall in FEV1 by methacholine (PC20) <8 mg . mL -1 (if the FEV1 was $70 % predicted (pred)) or an improvement in FEV1 of >12% after 200 mg of inhaled salbutamol (if the FEV1 was <70% pred) (table 1). The FEV...

AARC Clinical Practice Guideline: Effectiveness of Pharmacologic Airway Clearance Therapies in Hospitalized Patients

“…[45][46][47][48] These effects can occur despite pretreatment with ␤ agonists. [46][47][48][49][50][51][52] The safety of giving even one treatment of hypertonic saline depends on pretreatment with ␤ agonists, baseline pulmonary function, previous overuse of short-acting ␤ 2 agonists, nebulizer output, saline concentration, and treatment duration and frequency. 47,48 Administration of bronchodilators before mucolytic administration is time-consuming, and research is lacking to establish safety, stability, and efficacy of admixtures using both agents.…”

Biomarkers in asthma and allergic rhinitis

“…Nevertheless, many subjects experience this procedure as a burden. Another drawback holds that the overall percentage of analysable sputum samples, even in specialized centers, fails to reach 100% [78]. Finally, many inflammatory markers in sputum supernatant are affected by the (standard) processing techniques and more sensitive (sophisticated) assays are needed for optimal biomarker detection [67].…”

Airway inflammation in COPD: physiological outcome measures and induced sputum

“…Once it is understood how best to coax the subject to expectorate sputum and to recognise when this is accomplished, the procedure is successful in obtaining enough sputum for cell counts (w100 mg of selected sputum) in w90% of patients with COPD or asthma [59] and inw80% of healthy subjects. Although the repeatability of success has not been specifically examined, adequate specimens for differential cell counts were obtained in 95% of 122 inductions in subjects with COPD [63] and in 100% of subjects entered into trials of the effect of corticosteroid treatment [64][65][66].…”

“…The occurrence of bronchoconstriction can be reduced by using a relatively low output ultrasonic nebuliser, which does not reduce the success of induction [54,55], and by the inhalation of a b 2 -agonist (such as 200 mg albuterol) to bronchodilate and prevent constriction [53][54][55][56][57][58][59][60]. Also, if there is a particular safety concern (such as when the patient has a low FEV1 or has been treated with a long-acting b 2 -agonist or a short-acting b 2 -agonist more than twice daily, i.e.…”