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A randomized study of four different types of tympanostomy ventilation tubes – One-year follow-up
International Journal of Pediatric Otorhinolaryngology 89 (2016) 159e163
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: http://www.ijporlonline.com/
A randomized study of four different types of tympanostomy ventilation tubes e One-year follow-up n So € derman a, b, *, Johan Knutsson c, d, Claudia Priwin b, e, Anne-Charlotte Hesse Magnus von Unge c, d, f a
Dept of Otorhinolaryngology, Cityakuten, Stockholm, Sweden Division of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden €sterås Central Hospital, Sweden Dept of Otorhinolaryngology, Va d €sterås, Sweden Centre for Clinical Research, Uppsala University, County Hospital, Va e Dept of Otorhinolaryngology, Queen Sophias Hospital, Stockholm, Sweden f Dept. of Otorhinolaryngology, Akershus University Hospital and University of Oslo, Campus Ahus, Oslo, Norway b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 19 May 2016 Received in revised form 12 August 2016 Accepted 15 August 2016 Available online 17 August 2016
Objective: To compare four different types of tympanostomy ventilation tubes (VT); long-shaft and short-shaft silicone tubes and long-shaft and short-shaft fluoroplastic tubes, regarding time to extrusion and events of otorrhea. Methods: A prospective randomized controlled trial in children with bilateral recurrent acute otitis media or secretory otitis media; four hundred children were randomized to receive one type of VT in the right ear and another type in the left ear. Postoperatively the children were assessed every third month by an otolaryngologist to monitor the incidence of otorrhea and tube extrusion. Results: Out of the 400 children, 22 were excluded during surgery. Mean age was 35.3 months. A majority (63.8%) were boys. Forty-eight children were lost to follow up during the first year. Significantly more short-shaft VTs were extruded after 12 months compared to long-shaft VTs, regardless of material. Significantly higher incidence of otorrhea was found in the fluoroplastic VT ears compared to the silicone ones, regardless of length of tube. Conclusion: Long-shaft VTs last longer in the eardrum during the first year of treatment. Silicone tubes render a reduced risk of otorrhea during the first year of treatment. © 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Ventilation tubes Otorrhea Tympanostomy tubes Complications Secretory otitis media Extrusion Material
1. Introduction Otitis media is one of the most common diseases during childhood, and more than seventy percent of all children experience at least one episode of otitis media [1]. Acute otitis media can be treated with antibiotics, but resolves most often spontaneously, which is also the case for secretory otitis media (SOM). Still a large number of children require tympanostomy ventilation tubes (VTs) to prevent recurrent acute otitis media (rAOM) and prolonged hearing impairment, respectively. VT insertion under general anesthesia is currently the most common surgical procedure performed in children. In Sweden, harboring almost ten million inhabitants, approximately ten thousand children receive VTs
* Corresponding author. Dept of Otorhinolaryngology, Cityakuten, Olof Palmes Gata 9, S-111 37 Stockholm, Sweden. €derman). E-mail address: [email protected] (A.-C.H. So http://dx.doi.org/10.1016/j.ijporl.2016.08.010 0165-5876/© 2016 Elsevier Ireland Ltd. All rights reserved.
annually [2]. A study from 2000 showed that 6.8% of North American children were treated with VTs by the age of three years [3]. There are numerous types of VTs with differences in shape and material. Unfortunately, there are very few randomized studies comparing the effects of different types of tubes. Knowledge about probable time to extrusion and complication rate is mainly based on retrospective, observational studies, with the obvious weaknesses that non-randomized studies render. A systematic review of the literature on VT treatment concluded that there is not enough evidence to determine whether the design or material of the VT has any impact on its duration or effect [2]. The present randomized study compares four different VTs with the aim to elucidate differences in duration and complication rate based on the basic features of the VT, i.e. shape and material. Two fundamentally different VT shapes were identified in the multitude of shapes on the market, and were thus tested: long-shaft singleflanged and short-shaft double-flanged. The two most commonly
€derman et al. / International Journal of Pediatric Otorhinolaryngology 89 (2016) 159e163 A.-C.H. So
160
used materials were also identified, and tested: fluoroplastic and silicone. The aim of the study was to decide if shape and/or material of VTs had had influence on extrusion rate or events of otorrhea during the first year after insertion. 2. Material and methods Four hundred children between one and ten years of age, admitted into a tertiary referral ENT department in Stockholm for bilateral VT insertion for rAOM, SOM or a combination of both were included after informed consent by their caregivers. Exclusion criteria were previous VT treatment, on-going acute otitis media, Downs's syndrome and craniofacial malformations such as cleft palate. Four different types of tubes were tested (Fig. 1). Details are shown in Table 1. 1. 2. 3. 4.
Shepard VT (short-shaft double-flanged, fluoroplastic) Donaldson VT (short-shaft double-flanged, silicone) Long Armstrong VT (long-shaft single-flanged, silicone) Straight VT (long-shaft single-flanged, fluoroplastic)
Using non-transparent consecutively numbered envelopes, 400 children were randomized to receive a specific combination of two different types of VT each. Statistical software was used to arrange the pre-randomization preparation, so that in each combination only one VT parameter (shape or material) differed in each patient. The VTs were inserted in the anterior part of the tympanic membrane under general anesthesia. Surgery was performed at a teaching tertiary referral ENT unit in Stockholm. All surgeons at the unit, including young residents (with supervision when needed)
contributed to the study and performed the VT insertion. If the surgeon failed to insert the intended types of VT the patient was excluded from the study. After surgery, the children were examined by an otolaryngologist every three months, and at extra visits in between if the caregiver requested this, during one year or until six months had passed since the extrusion of the last remaining VT. At all postoperative examinations a form was filled out by the examiner indicating the presence of VT for each ear, purulent otorrhea, events of otalgia, observed VT occlusion, VT extraction, persistent perforation and presence of myringosclerosis. The Regional Ethical Review Board in Stockholm approved this study (ref. 2008/69e31/3). The study was registered at ClinicalTrials.gov (NCT00809601). 2.1. Statistical analysis A statistical power analysis indicated a need of a study population of four hundred children in order to answer the primary hypothesis (time to extrusion of VT) with 80% power at a 5% significance level. For comparison between two groups, Chi2-test and Fisher's exact test was used for dichotomous variables and the MannWhitney U test was used for continuous variables. The data was analyzed using SPSS software, version 22.0. 3. Results These are the results from the 1-year follow up. Twenty-two (5.5%) of the children were withdrawn from the study during surgery due to various reasons, including insertion failures with the intended VT type or when a acute otitis media was detected at myringotomy. Thus 378 children continued within the
€rby, Sweden). Fig. 1. Design of the four tested tubes. Provided by the retailer (Atos Medical AB, Ho
Table 1 €rby, Sweden). Measurements of each ventilation tube. Provided by retailer (Atos Medical AB, Ho
Shepard TT Donaldson TT Armstrong long TT Straight TT a b
Material
Length
fluoroplastic silicone silicone fluoroplastic
2.2 2.2 7.0 7.0
mma mma mmb mmb
Inner diameter
Flange diameter
Weight
1.10 1.10 1.14 1.14
2.4 2.3 2.6 2.7
9 9 9 9
mm mm mm mm
For double-flanged tubes the length refers to the distance between the flanges. For single-flanged tubes the length refers to the distance from the flange to the outer end of the tube.
mm mm mm mm
g g g g
€derman et al. / International Journal of Pediatric Otorhinolaryngology 89 (2016) 159e163 A.-C.H. So
161
Table 2 Number of ventilation tubes of each type and mean age at insertion. Distribution of indication for surgery and gender for the different tube types.
Shepard TT Donaldson TT Armstrong long TT Straight TT
Mean age at surgery
Indication for surgery (number of tubes)
n
Months (SD)
rAOM
rAOM & SOM
SOM
Girls
Boys
188 190 190 188
37.0 35.6 34.5 34.7
77 88 92 81
31 24 23 30
80 78 75 77
63 64 72 71
125 126 118 117
(19.9) (19.6) (19.9) (18.6)
(41.0%) (46.3%) (48.4%) (43.1%)
study. Indication for surgery was rAOM in 44.7%, SOM in 41.0% and a combination of rAOM and SOM in 14.3%. 35.7% were girls and 64.3% boys. Mean age at the time of surgery was 35.3 (SD 19.5) months for all children. The mean age for each group of VTs is presented in Table 2 as well as the number of inserted VTs, indication for surgery and gender for each type. 48 children (12.7%) were lost to follow up. There was no difference between the types of VT with regard to completion of follow up. At 12 months, examination revealed that 25.6% of the VTs had extruded. Signs of purulent discharge from the middle ear through the VT had been found in 4.1% of all postoperative examinations. The percentages for each type of VT are presented in Table 3. Due to sustained infection, occlusion or “other” reasons, 0.5% of the VTs were extracted during this first year after insertion. No difference was found between VTs of different length (p ¼ 0.89) or material (p ¼ 0.75) regarding rate of VT extraction. 3.1. Short-shaft vs long-shaft tympanostomy ventilating tubes, regardless of material At the twelve-month follow up, 42.1% of the short-shaft VTs had extruded compared to 10.0% of the long-shaft VTs. The difference was statistically significant (p < 0.001). The odds ratio for tube extrusion for a short-shaft tube compared to a long-shaft tube was 6.58 (95% CI 4.08e10.64). No statistically significant difference was found regarding events of otorrhea (p ¼ 0.065). 3.2. Fluoroplastic vs silicone tympanostomy ventilating tubes, regardless of length Purulent infection related to a fluoroplastic VT was found in 5.2% postoperatively. For the silicone VTs the corresponding rate was 2.9%. The difference was statistically significant (p ¼ 0.004). The odds ratio for otorrhea with a fluoroplastic VT compared to a silicone one was 1.83 (95% CI 1.20e2.79). Thus, otorrhea was present in approximately half as many cases of silicone as of fluoroplastic VTs. No difference was found between fluoroplastic and silicone VTs regarding time to extrusion (p ¼ 0.48). 4. Discussion The ideal VT should be easily inserted, resistant to early
(16.5%) (12.6%) (12.1%) (16.0%)
Gender (number of tubes)
(42.6%) (41.1%) (39.5%) (41.0%)
(33.5%) (33.7%) (37.9%) (37.8%)
(66.5%) (66.3%) (62.1%) (62.2%)
extrusion, immune to obstruction, and associated with minimal risk of otorrhea. There are numerous shapes of VTs and many of them are also available in several different materials. Thus, it is obvious that the ideal tube still is lacking and it is unclear to what extent tube shape and material have an impact on time to extrusion and complication rates. 4.1. Time to extrusion Usually, it is desirable for the VT to stay in place for a long time, but not always. For example, a VT might be used during hearing tests to ensure that temporary SOM won't interfere with testing. In other cases, VT treatment may be warranted for a more limited time period, when a less severe rAOM or SOM situation is at hand. In many cases, however, early extrusion results in the need for a second VT insertion. In a clinical study, the exact date on which the VT extrudes is of course very difficult to monitor. Instead, the extrusion must be assumed to have occurred in the interval between two consecutive examinations, with the former recording VT in situ [4]. In the present study the children were examined every third month, which is a practical and reasonable compromise between a desired high frequency of examination and the children's and families' convenience. 4.2. Possible mechanisms causing extrusion The mechanisms behind VT extrusion are not fully known. A theory that has been discussed suggests that an accumulation of epithelial debris under an outer flange in short VTs leads to compression of the tympanic membrane tissues under the flange. This could in turn lead to a compromised blood flow and local pressure necrosis around the tube, making it easier for the tube to leave the tympanic membrane. Furthermore, the accumulated keratin debris might produce an outward directed force upon the outer flange [5]. Obviously, that phenomenon cannot take place if there is no outer flange as in long-shaft single-flanged VTs, where the mechanism of extrusion is unclear. One might speculate that the relatively large momentum effect of a long-shaft VT might disturb the tympanic membrane tissue at the perforation rim, as well as it per se serves as a foreign body irritating the tissue. Normally, the VT has an inner flange to avoid extrusion, and the time to extrusion has been found dependent on the diameter and shape of the inner flange [4e7]. Most VTs with an inner flange diameter of up to 2.5 mm become extruded within 8e24 months. If
Table 3 Results for each type of ventilation tube.
Shepard TT Donaldson TT Armstrong long TT Straight TT
Material
Shape
Extruded after 1 year
Purulent discharge at examination
fluoroplastic silicone silicone fluoroplastic
short short long long
45.0% 39.0% 10.3% 9.6%
4.6% 1.9% 3.7% 5.7%
162
€derman et al. / International Journal of Pediatric Otorhinolaryngology 89 (2016) 159e163 A.-C.H. So
the inner flange is wider or T-shaped, the time to extrusion is prolonged to more than 2 years [6]. VTs with wider flanges such as the Goode T-tube cause higher rates of chronic perforations. The weight of the tube also plays a role where those of lower weight remain for a shorter time but result in less myringosclerosis [7e9]. There is little published on the effects of the different VT types and their materials. However, a few prospective studies are reported, most of them of an early date. In a prospective study on the impact of material on time to extrusion, twice as many titanium VTs compared to Shepard Teflon VTs were retained after 8 months, but this difference was not significant after 16 months [10]. Coating of VTs with human serum albumin reduced the blockage rate by 50% but did not influence the time to extrusion and rate of infections [11]. A prospective randomized study of 75 patients comparing Shepard (short-shaft VT, Teflon), Armstrong (long-shaft VT, Teflon), Reuter-Bobbin (short-shaft VT, stainless steel) and Goode T-tubes (long-shaft VT, silicone) [6], found a higher percentage of extrusion, but not statistically significant, for the Teflon Shepard VT compared to the Armstrong VT. The Reuter-Bobbin tube had a significantly greater rate of plugging compared to the other tubes. The T-tube caused an increased incidence of otorrhea and retention in the tympanic membrane well beyond 1 year. In an observational study of 186 ears with Shepard tubes, Todd found that 91.4% of the tubes had extruded after 12 months, which is very similar to our results with the short-shaft double-flanged VTs [12]. The largest observational study to date, reported the outcome of 1096 Armstrong VTs through retrospective chart reviews, but did not specify material or whether the VT was of the short-shaft or long-shaft variant. A mean time to extrusion of 16.22 months for the right ear and 16.84 months for the left ear was reported [13]. 4.3. Tympanostomy ventilation tube and otorrhea Otorrhea is a clinical problem and results in many health care contacts. According to a meta-analysis recurrent otorrhea occurs in 7.4% of patients and chronic otorrhea in 3.8% [14]. In the present study, signs of purulent discharge were seen in 4.4% of all postoperative examinations. The lower percentage in the present study is affected by the high number of examinations per year (and thus symptom free examinations) that was warranted by the study protocol. In comparison, the frequency of examinations that is generally recommended in Sweden is once yearly for uncomplicated, trouble-free cases with satisfying hearing.
coating with anti-bacterial agents. Licameli et al. compared uncoated and phosphorylcholine-coated fluoroplastic Armstrong VTs in 70 patients but did not find any significantly different complication rate [19]. Silastic VTs impregnated with silver oxide have been shown to diminish the incidence of postoperative otorrhea in ears requiring long-term ventilation in a study on 125 children [20]. Another limited study on 46 patients showed that ionized, processed silicone VTs were more resistant to bacterial biofilm growth compared to other silicone tympanostomy tubes [21]. Compared with the previously published reports, the present study is by far the largest and the first randomized study reporting a clear difference in frequency of otorrhea between fluoroplastic and silicone VTs. 4.5. Limitation of the study The two long-shaft VTs are not exactly similar in shape as the Armstrong VT has a beveled flange whereas the angle between the flange and the shaft of the straight tube is ninety degrees. The two short-shaft VTs have minor differences in shape. The four types of VTs all have minor differences in the flange diameter. At the time of the start of the study, VTs with exactly the same appearance but in different materials were not available. Conversely, the use of only commercially available VTs increases the generalizability and the immediate clinical impact of the study results. 5. Conclusions Long-shaft VTs last longer in situ in the eardrum when compared to short-shaft VTs, and silicone VTs have a reduced risk of otorrhea when compared to fluoroplastic VTs in a one-year follow-up. Consequently, a long-shaft silicone tympanostomy tube could in many cases be preferable in the treatment of otitis media with transmyringeal VTs. Conflict of interests None of the presenters have any financial or other relationship with the manufacturers or distributors of ventilation tubes. Financial support The study was supported by Aleris research fund and Centre for €stmanland County e Uppsala University. Clinical Research Va
4.4. Possible mechanisms
Acknowledgements
The genesis of a purulent otorrhea in VT ears is not fully clarified, but the occurrence of a biofilm might be of importance. Bacterial biofilms may result in irreversible contaminations of implanted medical materials such as VTs. Biofilms have been shown on VTs retrieved from children with chronic discharge [15]. This finding provides a plausible explanation of the intractability of severe, lateonset chronic post-VT otorrhea [16]. In a recent review, the role of biofilms to post-VT otorrhea and VT plugging was assessed, concluding that “currently, there is not one type of tympanostomy tube in which bacteria will not adhere” [17] and stresses the importance of further research in VT design. Comparative clinical studies on otorrhea rates for different VT types are scarce. A retrospective study on a number of different VTs, including Shepard, Shah, Paparella type 2, Goode and Reuter Bobbin concluded that the Paparella tubes were associated with a higher rate of otorrhea. Unfortunately, the shape and material of the VTs are not described [18]. Various VT coatings have been tried in efforts to minimize the events of purulent discharge, including
The study was supported by Aleris Research Fund and Centre for €stmanland County e Uppsala University. Clinical Research Va The authors want to thank the otolaryngologists in private practice that have supplied the data from the follow-up visits and €stmanland County e Tony Wiklund, Centre for Clinical Research Va Uppsala University for help with data analyses. The authors also want to thank native English speaker Jeremy Wales, MD, PhD, for advice on our English syntax and grammar. References [1] D.W. Teele, J.O. Klein, B. Rosner, Epidemiology of otitis media during the first seven years of life in children in greater Boston: a prospective, cohort study, J. Infect. Dis. 160 (1) (1989 Jul) 83e94. PubMed PMID: 2732519. [2] S. Hellstrom, A. Groth, F. Jorgensen, A. Pettersson, M. Ryding, I. Uhlen, et al., Ventilation tube treatment: a systematic review of the literature, Otolaryngol. Head Neck Surg.: Off. J. Am. Acad. Otolaryngol. Head Neck Surg. 145 (3) (2011 Sep) 383e395. PubMed PMID: 21632976. [3] M.D. Kogan, M.D. Overpeck, H.J. Hoffman, M.L. Casselbrant, Factors associated with tympanostomy tube insertion among preschool-aged children in the
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United States, Am. J. Public Health 90 (2) (2000 Feb) 245e250. PubMed PMID: 10667186. Pubmed Central PMCID: 1446140. J. Knutsson, M. von Unge, Five-year results for use of single-flanged tympanostomy tubes in children, J. Laryngol. Otol. 122 (6) (2008 Jun) 584e589. PubMed PMID: 17666133. J.D. Hern, D.A. Jonathan, Insertion of ventilation tubes: does the site matter? Clin. Otolaryngol. Allied Sci. 24 (5) (1999 Sep) 424e425. PubMed PMID: 10542923. M.T. Weigel, M.Y. Parker, M.M. Goldsmith, D.S. Postma, H.C. Pillsbury, A prospective randomized study of four commonly used tympanostomy tubes, Laryngosc. 99 (3) (1989 Mar) 252e256. PubMed PMID: 2645490. S. Hampal, L.M. Flood, B.U. Kumar, The mini-grommet and tympanosclerosis, J. Laryngol. Otol. 105 (3) (1991 Mar) 161e164. PubMed PMID: 2019798. A.F. Dingle, L.M. Flood, B.U. Kumar, S. Hampal, The mini-grommet and tympanosclerosis: results at two years, J. Laryngol. Otol. 107 (2) (1993 Feb) 108e110. PubMed PMID: 8496640. F. Gordts, P.A. Clement, M.P. Derde, Lens tube vs Donaldson tube: results of a prospective study comparing a new with a conventional ventilation tube, Clin. Otolaryngol. Allied Sci. 18 (5) (1993 Oct) 410e414. PubMed PMID: 8877210. G.R. Shone, I.P. Griffith, Titanium grommets: a trial to assess function and extrusion rates, J. Laryngol. Otol. 104 (3) (1990 Mar) 197e199. PubMed PMID: 2341773. T.J. Kinnari, H. Rihkanen, T. Laine, E.M. Salonen, J. Jero, Albumin-coated tympanostomy tubes: prospective, double-blind clinical study, Laryngosc. 114 (11) (2004 Nov) 2038e2043. PubMed PMID: 15510039. G.B. Todd, Audit of the incidence of persistent perforation of the tympanic membrane following grommet removal or extrusion, J. Laryngol. Otol. 107 (7) (1993 Jul) 593e596. PubMed PMID: 15125273. D.R. Lindstrom, B. Reuben, K. Jacobson, V.A. Flanary, J.E. Kerschner, Long-term
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results of Armstrong beveled grommet tympanostomy tubes in children, Laryngosc. 114 (3) (2004 Mar) 490e494. PubMed PMID: 15091223. D.J. Kay, M. Nelson, R.M. Rosenfeld, Meta-analysis of tympanostomy tube sequelae, Otolaryngol. Head Neck Surg.: Off. J. Am. Acad. Otolaryngol. Head Neck Surg. 124 (4) (2001 Apr) 374e380. PubMed PMID: 11283489. J.C. Post, Direct evidence of bacterial biofilms in otitis media, Laryngosc. 111 (12) (2001 Dec) 2083e2094. PubMed PMID: 11802002. J.P. Oberman, C.S. Derkay, Posttympanostomy tube otorrhea, Am. J. Otolaryngol. 25 (2) (2004 Mar-Apr) 110e117. PubMed PMID: 14976657. J.C. Wang, A.N. Hamood, C. Saadeh, M.J. Cunningham, M.T. Yim, J. Cordero, Strategies to prevent biofilm-based tympanostomy tube infections, Int. J. Pediatr. Otorhinolaryngol. 78 (9) (2014 Sep) 1433e1438. PubMed PMID: 25060938. R.W. Slack, J.M. Gardner, C. Chatfield, Otorrhoea in children with middle ear ventilation tubes: a comparison of different types of tubes, Clin. Otolaryngol. Allied Sci. 12 (5) (1987 Oct) 357e360. PubMed PMID: 3427799. G. Licameli, P. Johnston, J. Luz, J. Daley, M. Kenna, Phosphorylcholine-coated antibiotic tympanostomy tubes: are post-tube placement complications reduced? Int. J. Pediatr. Otorhinolaryngol. 72 (9) (2008 Sep) 1323e1328. PubMed PMID: 18635268. R.A. Chole, R.N. Hubbell, Antimicrobial activity of silastic tympanostomy tubes impregnated with silver oxide. A double-blind randomized multicenter trial, Arch. Otolaryngol. Head Neck Surg. 121 (5) (1995 May) 562e565. PubMed PMID: 7727091. E.C. Tatar, F.O. Unal, I. Tatar, H.H. Celik, B. Gursel, Investigation of surface changes in different types of ventilation tubes using scanning electron microscopy and correlation of findings with clinical follow-up, Int. J. Pediatr. Otorhinolaryngol. 70 (3) (2006 Mar) 411e417. PubMed PMID: 16125252.
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: http://www.ijporlonline.com/
A randomized study of four different types of tympanostomy ventilation tubes e One-year follow-up n So € derman a, b, *, Johan Knutsson c, d, Claudia Priwin b, e, Anne-Charlotte Hesse Magnus von Unge c, d, f a
Dept of Otorhinolaryngology, Cityakuten, Stockholm, Sweden Division of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden €sterås Central Hospital, Sweden Dept of Otorhinolaryngology, Va d €sterås, Sweden Centre for Clinical Research, Uppsala University, County Hospital, Va e Dept of Otorhinolaryngology, Queen Sophias Hospital, Stockholm, Sweden f Dept. of Otorhinolaryngology, Akershus University Hospital and University of Oslo, Campus Ahus, Oslo, Norway b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 19 May 2016 Received in revised form 12 August 2016 Accepted 15 August 2016 Available online 17 August 2016
Objective: To compare four different types of tympanostomy ventilation tubes (VT); long-shaft and short-shaft silicone tubes and long-shaft and short-shaft fluoroplastic tubes, regarding time to extrusion and events of otorrhea. Methods: A prospective randomized controlled trial in children with bilateral recurrent acute otitis media or secretory otitis media; four hundred children were randomized to receive one type of VT in the right ear and another type in the left ear. Postoperatively the children were assessed every third month by an otolaryngologist to monitor the incidence of otorrhea and tube extrusion. Results: Out of the 400 children, 22 were excluded during surgery. Mean age was 35.3 months. A majority (63.8%) were boys. Forty-eight children were lost to follow up during the first year. Significantly more short-shaft VTs were extruded after 12 months compared to long-shaft VTs, regardless of material. Significantly higher incidence of otorrhea was found in the fluoroplastic VT ears compared to the silicone ones, regardless of length of tube. Conclusion: Long-shaft VTs last longer in the eardrum during the first year of treatment. Silicone tubes render a reduced risk of otorrhea during the first year of treatment. © 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Ventilation tubes Otorrhea Tympanostomy tubes Complications Secretory otitis media Extrusion Material
1. Introduction Otitis media is one of the most common diseases during childhood, and more than seventy percent of all children experience at least one episode of otitis media [1]. Acute otitis media can be treated with antibiotics, but resolves most often spontaneously, which is also the case for secretory otitis media (SOM). Still a large number of children require tympanostomy ventilation tubes (VTs) to prevent recurrent acute otitis media (rAOM) and prolonged hearing impairment, respectively. VT insertion under general anesthesia is currently the most common surgical procedure performed in children. In Sweden, harboring almost ten million inhabitants, approximately ten thousand children receive VTs
* Corresponding author. Dept of Otorhinolaryngology, Cityakuten, Olof Palmes Gata 9, S-111 37 Stockholm, Sweden. €derman). E-mail address: [email protected] (A.-C.H. So http://dx.doi.org/10.1016/j.ijporl.2016.08.010 0165-5876/© 2016 Elsevier Ireland Ltd. All rights reserved.
annually [2]. A study from 2000 showed that 6.8% of North American children were treated with VTs by the age of three years [3]. There are numerous types of VTs with differences in shape and material. Unfortunately, there are very few randomized studies comparing the effects of different types of tubes. Knowledge about probable time to extrusion and complication rate is mainly based on retrospective, observational studies, with the obvious weaknesses that non-randomized studies render. A systematic review of the literature on VT treatment concluded that there is not enough evidence to determine whether the design or material of the VT has any impact on its duration or effect [2]. The present randomized study compares four different VTs with the aim to elucidate differences in duration and complication rate based on the basic features of the VT, i.e. shape and material. Two fundamentally different VT shapes were identified in the multitude of shapes on the market, and were thus tested: long-shaft singleflanged and short-shaft double-flanged. The two most commonly
€derman et al. / International Journal of Pediatric Otorhinolaryngology 89 (2016) 159e163 A.-C.H. So
160
used materials were also identified, and tested: fluoroplastic and silicone. The aim of the study was to decide if shape and/or material of VTs had had influence on extrusion rate or events of otorrhea during the first year after insertion. 2. Material and methods Four hundred children between one and ten years of age, admitted into a tertiary referral ENT department in Stockholm for bilateral VT insertion for rAOM, SOM or a combination of both were included after informed consent by their caregivers. Exclusion criteria were previous VT treatment, on-going acute otitis media, Downs's syndrome and craniofacial malformations such as cleft palate. Four different types of tubes were tested (Fig. 1). Details are shown in Table 1. 1. 2. 3. 4.
Shepard VT (short-shaft double-flanged, fluoroplastic) Donaldson VT (short-shaft double-flanged, silicone) Long Armstrong VT (long-shaft single-flanged, silicone) Straight VT (long-shaft single-flanged, fluoroplastic)
Using non-transparent consecutively numbered envelopes, 400 children were randomized to receive a specific combination of two different types of VT each. Statistical software was used to arrange the pre-randomization preparation, so that in each combination only one VT parameter (shape or material) differed in each patient. The VTs were inserted in the anterior part of the tympanic membrane under general anesthesia. Surgery was performed at a teaching tertiary referral ENT unit in Stockholm. All surgeons at the unit, including young residents (with supervision when needed)
contributed to the study and performed the VT insertion. If the surgeon failed to insert the intended types of VT the patient was excluded from the study. After surgery, the children were examined by an otolaryngologist every three months, and at extra visits in between if the caregiver requested this, during one year or until six months had passed since the extrusion of the last remaining VT. At all postoperative examinations a form was filled out by the examiner indicating the presence of VT for each ear, purulent otorrhea, events of otalgia, observed VT occlusion, VT extraction, persistent perforation and presence of myringosclerosis. The Regional Ethical Review Board in Stockholm approved this study (ref. 2008/69e31/3). The study was registered at ClinicalTrials.gov (NCT00809601). 2.1. Statistical analysis A statistical power analysis indicated a need of a study population of four hundred children in order to answer the primary hypothesis (time to extrusion of VT) with 80% power at a 5% significance level. For comparison between two groups, Chi2-test and Fisher's exact test was used for dichotomous variables and the MannWhitney U test was used for continuous variables. The data was analyzed using SPSS software, version 22.0. 3. Results These are the results from the 1-year follow up. Twenty-two (5.5%) of the children were withdrawn from the study during surgery due to various reasons, including insertion failures with the intended VT type or when a acute otitis media was detected at myringotomy. Thus 378 children continued within the
€rby, Sweden). Fig. 1. Design of the four tested tubes. Provided by the retailer (Atos Medical AB, Ho
Table 1 €rby, Sweden). Measurements of each ventilation tube. Provided by retailer (Atos Medical AB, Ho
Shepard TT Donaldson TT Armstrong long TT Straight TT a b
Material
Length
fluoroplastic silicone silicone fluoroplastic
2.2 2.2 7.0 7.0
mma mma mmb mmb
Inner diameter
Flange diameter
Weight
1.10 1.10 1.14 1.14
2.4 2.3 2.6 2.7
9 9 9 9
mm mm mm mm
For double-flanged tubes the length refers to the distance between the flanges. For single-flanged tubes the length refers to the distance from the flange to the outer end of the tube.
mm mm mm mm
g g g g
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161
Table 2 Number of ventilation tubes of each type and mean age at insertion. Distribution of indication for surgery and gender for the different tube types.
Shepard TT Donaldson TT Armstrong long TT Straight TT
Mean age at surgery
Indication for surgery (number of tubes)
n
Months (SD)
rAOM
rAOM & SOM
SOM
Girls
Boys
188 190 190 188
37.0 35.6 34.5 34.7
77 88 92 81
31 24 23 30
80 78 75 77
63 64 72 71
125 126 118 117
(19.9) (19.6) (19.9) (18.6)
(41.0%) (46.3%) (48.4%) (43.1%)
study. Indication for surgery was rAOM in 44.7%, SOM in 41.0% and a combination of rAOM and SOM in 14.3%. 35.7% were girls and 64.3% boys. Mean age at the time of surgery was 35.3 (SD 19.5) months for all children. The mean age for each group of VTs is presented in Table 2 as well as the number of inserted VTs, indication for surgery and gender for each type. 48 children (12.7%) were lost to follow up. There was no difference between the types of VT with regard to completion of follow up. At 12 months, examination revealed that 25.6% of the VTs had extruded. Signs of purulent discharge from the middle ear through the VT had been found in 4.1% of all postoperative examinations. The percentages for each type of VT are presented in Table 3. Due to sustained infection, occlusion or “other” reasons, 0.5% of the VTs were extracted during this first year after insertion. No difference was found between VTs of different length (p ¼ 0.89) or material (p ¼ 0.75) regarding rate of VT extraction. 3.1. Short-shaft vs long-shaft tympanostomy ventilating tubes, regardless of material At the twelve-month follow up, 42.1% of the short-shaft VTs had extruded compared to 10.0% of the long-shaft VTs. The difference was statistically significant (p < 0.001). The odds ratio for tube extrusion for a short-shaft tube compared to a long-shaft tube was 6.58 (95% CI 4.08e10.64). No statistically significant difference was found regarding events of otorrhea (p ¼ 0.065). 3.2. Fluoroplastic vs silicone tympanostomy ventilating tubes, regardless of length Purulent infection related to a fluoroplastic VT was found in 5.2% postoperatively. For the silicone VTs the corresponding rate was 2.9%. The difference was statistically significant (p ¼ 0.004). The odds ratio for otorrhea with a fluoroplastic VT compared to a silicone one was 1.83 (95% CI 1.20e2.79). Thus, otorrhea was present in approximately half as many cases of silicone as of fluoroplastic VTs. No difference was found between fluoroplastic and silicone VTs regarding time to extrusion (p ¼ 0.48). 4. Discussion The ideal VT should be easily inserted, resistant to early
(16.5%) (12.6%) (12.1%) (16.0%)
Gender (number of tubes)
(42.6%) (41.1%) (39.5%) (41.0%)
(33.5%) (33.7%) (37.9%) (37.8%)
(66.5%) (66.3%) (62.1%) (62.2%)
extrusion, immune to obstruction, and associated with minimal risk of otorrhea. There are numerous shapes of VTs and many of them are also available in several different materials. Thus, it is obvious that the ideal tube still is lacking and it is unclear to what extent tube shape and material have an impact on time to extrusion and complication rates. 4.1. Time to extrusion Usually, it is desirable for the VT to stay in place for a long time, but not always. For example, a VT might be used during hearing tests to ensure that temporary SOM won't interfere with testing. In other cases, VT treatment may be warranted for a more limited time period, when a less severe rAOM or SOM situation is at hand. In many cases, however, early extrusion results in the need for a second VT insertion. In a clinical study, the exact date on which the VT extrudes is of course very difficult to monitor. Instead, the extrusion must be assumed to have occurred in the interval between two consecutive examinations, with the former recording VT in situ [4]. In the present study the children were examined every third month, which is a practical and reasonable compromise between a desired high frequency of examination and the children's and families' convenience. 4.2. Possible mechanisms causing extrusion The mechanisms behind VT extrusion are not fully known. A theory that has been discussed suggests that an accumulation of epithelial debris under an outer flange in short VTs leads to compression of the tympanic membrane tissues under the flange. This could in turn lead to a compromised blood flow and local pressure necrosis around the tube, making it easier for the tube to leave the tympanic membrane. Furthermore, the accumulated keratin debris might produce an outward directed force upon the outer flange [5]. Obviously, that phenomenon cannot take place if there is no outer flange as in long-shaft single-flanged VTs, where the mechanism of extrusion is unclear. One might speculate that the relatively large momentum effect of a long-shaft VT might disturb the tympanic membrane tissue at the perforation rim, as well as it per se serves as a foreign body irritating the tissue. Normally, the VT has an inner flange to avoid extrusion, and the time to extrusion has been found dependent on the diameter and shape of the inner flange [4e7]. Most VTs with an inner flange diameter of up to 2.5 mm become extruded within 8e24 months. If
Table 3 Results for each type of ventilation tube.
Shepard TT Donaldson TT Armstrong long TT Straight TT
Material
Shape
Extruded after 1 year
Purulent discharge at examination
fluoroplastic silicone silicone fluoroplastic
short short long long
45.0% 39.0% 10.3% 9.6%
4.6% 1.9% 3.7% 5.7%
162
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the inner flange is wider or T-shaped, the time to extrusion is prolonged to more than 2 years [6]. VTs with wider flanges such as the Goode T-tube cause higher rates of chronic perforations. The weight of the tube also plays a role where those of lower weight remain for a shorter time but result in less myringosclerosis [7e9]. There is little published on the effects of the different VT types and their materials. However, a few prospective studies are reported, most of them of an early date. In a prospective study on the impact of material on time to extrusion, twice as many titanium VTs compared to Shepard Teflon VTs were retained after 8 months, but this difference was not significant after 16 months [10]. Coating of VTs with human serum albumin reduced the blockage rate by 50% but did not influence the time to extrusion and rate of infections [11]. A prospective randomized study of 75 patients comparing Shepard (short-shaft VT, Teflon), Armstrong (long-shaft VT, Teflon), Reuter-Bobbin (short-shaft VT, stainless steel) and Goode T-tubes (long-shaft VT, silicone) [6], found a higher percentage of extrusion, but not statistically significant, for the Teflon Shepard VT compared to the Armstrong VT. The Reuter-Bobbin tube had a significantly greater rate of plugging compared to the other tubes. The T-tube caused an increased incidence of otorrhea and retention in the tympanic membrane well beyond 1 year. In an observational study of 186 ears with Shepard tubes, Todd found that 91.4% of the tubes had extruded after 12 months, which is very similar to our results with the short-shaft double-flanged VTs [12]. The largest observational study to date, reported the outcome of 1096 Armstrong VTs through retrospective chart reviews, but did not specify material or whether the VT was of the short-shaft or long-shaft variant. A mean time to extrusion of 16.22 months for the right ear and 16.84 months for the left ear was reported [13]. 4.3. Tympanostomy ventilation tube and otorrhea Otorrhea is a clinical problem and results in many health care contacts. According to a meta-analysis recurrent otorrhea occurs in 7.4% of patients and chronic otorrhea in 3.8% [14]. In the present study, signs of purulent discharge were seen in 4.4% of all postoperative examinations. The lower percentage in the present study is affected by the high number of examinations per year (and thus symptom free examinations) that was warranted by the study protocol. In comparison, the frequency of examinations that is generally recommended in Sweden is once yearly for uncomplicated, trouble-free cases with satisfying hearing.
coating with anti-bacterial agents. Licameli et al. compared uncoated and phosphorylcholine-coated fluoroplastic Armstrong VTs in 70 patients but did not find any significantly different complication rate [19]. Silastic VTs impregnated with silver oxide have been shown to diminish the incidence of postoperative otorrhea in ears requiring long-term ventilation in a study on 125 children [20]. Another limited study on 46 patients showed that ionized, processed silicone VTs were more resistant to bacterial biofilm growth compared to other silicone tympanostomy tubes [21]. Compared with the previously published reports, the present study is by far the largest and the first randomized study reporting a clear difference in frequency of otorrhea between fluoroplastic and silicone VTs. 4.5. Limitation of the study The two long-shaft VTs are not exactly similar in shape as the Armstrong VT has a beveled flange whereas the angle between the flange and the shaft of the straight tube is ninety degrees. The two short-shaft VTs have minor differences in shape. The four types of VTs all have minor differences in the flange diameter. At the time of the start of the study, VTs with exactly the same appearance but in different materials were not available. Conversely, the use of only commercially available VTs increases the generalizability and the immediate clinical impact of the study results. 5. Conclusions Long-shaft VTs last longer in situ in the eardrum when compared to short-shaft VTs, and silicone VTs have a reduced risk of otorrhea when compared to fluoroplastic VTs in a one-year follow-up. Consequently, a long-shaft silicone tympanostomy tube could in many cases be preferable in the treatment of otitis media with transmyringeal VTs. Conflict of interests None of the presenters have any financial or other relationship with the manufacturers or distributors of ventilation tubes. Financial support The study was supported by Aleris research fund and Centre for €stmanland County e Uppsala University. Clinical Research Va
4.4. Possible mechanisms
Acknowledgements
The genesis of a purulent otorrhea in VT ears is not fully clarified, but the occurrence of a biofilm might be of importance. Bacterial biofilms may result in irreversible contaminations of implanted medical materials such as VTs. Biofilms have been shown on VTs retrieved from children with chronic discharge [15]. This finding provides a plausible explanation of the intractability of severe, lateonset chronic post-VT otorrhea [16]. In a recent review, the role of biofilms to post-VT otorrhea and VT plugging was assessed, concluding that “currently, there is not one type of tympanostomy tube in which bacteria will not adhere” [17] and stresses the importance of further research in VT design. Comparative clinical studies on otorrhea rates for different VT types are scarce. A retrospective study on a number of different VTs, including Shepard, Shah, Paparella type 2, Goode and Reuter Bobbin concluded that the Paparella tubes were associated with a higher rate of otorrhea. Unfortunately, the shape and material of the VTs are not described [18]. Various VT coatings have been tried in efforts to minimize the events of purulent discharge, including
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