Single use and conventional bronchoscopes for Broncho alveolar lavage (BAL) in research: a comparative study (NCT 02515591)

Flexible bronchoscopy is widely performed in adults and children for investigation of pulmonary pathology [1, 2]. Broncho alveolar lavage (BAL) sampling is used to study innate, cellular and humoral immune responses, determining the cell population profiles that can facilitate the diagnosis of various diffuse lung diseases [3‐7]. It is used in early phase drug development studies and has a well-proven safety record in both research and in clinical applications. BAL is easily performed and well-tolerated with rare complications [8‐10].

Typically, conventional flexible bronchoscopes are used but they are associated with significant costs related to initial purchase, ongoing maintenance, and sterilisation [11, 12]. Single use bronchoscopes offer an alternative [11] and are currently used in many UK NHS trusts for both emergency and elective airway intubations [13]. Single use scopes are more portable, and might also improve working efficiency [12]. Their efficacy for research studies has not yet been demonstrated, notably in research BAL the cell number and viability, and the returned volume of epithelial lining fluid is critical. Maximising the volume of BAL fluid returned has potential advantages to both researchers and participants: procedures that return less than 100 mL are more frequently associated with side effects such as cough, pleuritic chest pain and fever. Larger total instilled volumes of a minimum of 100 mL and a recommended standard 240 mL using standard 4 × 60 mL aliquots have therefore been recommended by the European Respiratory Society (ERS) to improve standardization when more efficient alveolar sampling and accurate quantitative measurements are required [14]. For cellular studies, function and viability are important, and may be maximised by the use of manual suction which minimises cellular shear forces [8]. Rapid processing by designated laboratory staff highly trained in handling of BALF (BAL fluid) samples is ideal. However, it should be noted that there is no strong relationship between the volumes returned and cell numbers obtained (unpublished data from our group).

This study presents a comparison of single use disposable bronchoscopes and conventional bronchoscopes with regards to BAL volumes, cell yields and viability using each method.

The aim of the study was to compare the BAL volume yield, total cell yield and viability between samples obtained using single use and conventional bronchoscopes. Table 1 compares different features of the single use and flexible bronchoscopes.

Ten participants (6 male), mean age of 23.4 years (range 20–26 years) were enrolled. All participants were intubated nasally, and only one requested sedation (midazolam 3 mg used). The median BAL volume yield from the single-use bronchoscopes was 152 mL (IQR 141–166 mL) as compared to conventional 124 mL (110–135 mL), p < 0.01 (Fig. 1). The median total cell yield from single-use bronchoscopes was 7.33 × 10⁶ (5.13 × 10⁶–9.80 × 10⁶) compared with 7.0 × 10⁶ (4.53 × 10⁶–1.64 × 10⁷) for conventional procedures, p = 0.61 (Fig. 2). The median cell viability for samples from single use bronchoscopes was 98.5% (93.8–100) compared to 98.2% (93.7–100%), p = 0.75 (Fig. 3). The comparison for the demographics is described in Table 2.

Broncho alveolar lavage with single-use flexible bronchoscope achieved greater BAL volume yields than with conventional bronchoscopes. There was no significant difference between the cell yield and viability between the methods.

Single-use bronchoscopes have been evaluated in the critical care setting with favourable evaluation for bronchoscopy, tracheostomy, intubation and suction [11]. Our group has experience of over 1500 research BALs, and the procedures in this study were performed by senior bronchoscopists with extensive experience of BAL for research purposes; allowing good comparison with the use of conventional bronchoscopes. BAL volume yields were similar in male and female participants in our study, as seen in other studies [15].

The greater BAL volume return achieved with single-use bronchoscopes could lead to reduced risk of post-procedural side effects such as cough, pleuritic chest pain and fever, which may improve tolerability and participant comfort. However, we have not systematically collected these data.

Single use flexible bronchoscopes have the potential for use in pharmaceutical preclinical and clinical studies for medicine development.

Single-use flexible bronchoscopes can be used to obtain BAL for research purposes to study immune responses and in early phase drug development studies.