Prevention and treatment of plugged tympanostomy tubes.

The placement of tympanostomy tubes was pioneered by Politzer in the 19th century, but the procedure was soon abandoned because of a high rate of complications. (1) In 1954, Armstrong (1) "reinvented" the procedure, and it became widely accepted. Today, tympanostomy tube placement has become the most common procedure performed in children under general anesthesia. (2)

When Armstrong reintroduced tympanostomy tube placement, he wrote, "An ideal tube should not plug or extrude prematurely, should be inserted and removed easily and should have a low complication rate." (1) However, plugging of tympanostomy tubes remains a common complication, occurring in 7 to 10.5% of cases, which amounts to perhaps 100,000 cases per year. (3,4)

Consequences of plugged tubes

A plugged tube can cause symptomatic otitis media and lead to hearing loss secondary to a lack of ventilation in the middle ear. Tube obstruction may also lead to tube extrusion. (5,6)

On a larger scale, the ramifications of occluded tubes include higher costs to the healthcare system. Many clinicians may not recognize the direct healthcare expenditures and indirect nonmedical costs that are associated with plugged tubes. The direct costs include an increase in the number of office visits and the cost of drops or remedies used to unblock a tube; if conservative therapy fails, reoperation becomes necessary. Indirect nonmedical costs include transportation expenses, lost wages, and missed school time.

Etiology of plugged tubes

Among the possible causes of tympanostomy tube plugging are an accumulation of wax and/or keratin, perioperative bleeding, middle ear effusion, and the presence of biofilms. (7,8)

Reid et al studied blocked tubes by light microscopy. (7) They found that in 56% of the tubes, the luminal material was made up of eosinophilic coagulum that had been infiltrated by leukocytes. They also found that in 70% of extruded tubes, the base of the tube was covered with a cast of squamous epithelium that had been derived from middle ear effusion. Finally, they found a statistically significant association between tube blockage and the presence of thick middle ear fluid.

Westine et al studied the biochemical composition of tube plugs by high-performance liquid chromatography (HPLC). (8) They compared the HPLC profiles of three substances potentially responsible for tube plugs: blood, cerumen, and mucoid middle ear effusion. Their HPLC amino acid and monosaccharide analyses revealed that the likely cause was mucoid effusion. They concluded that tube plugs are not products of cerumen and blood. Cerumen is produced in the lateral auditory canal and is not likely to move against the direction of natural migration. (6) Although blood might become mixed in with mucoid middle ear effusion, it is more of a problem during the immediate postoperative period.

The type of material used to manufacture a tube might have an effect on plugging. (7,9-14) Theoretically, using a tube with a very smooth surface would reduce the risk of bacterial adherence and prevent occlusion. Tsao et al studied the association between tube composition and plugging in six types of tubes: stainless steel, titanium, silicone, ion-bombarded silicone, fluoroplastic, and phosphorylcholine-coated fluoroplastic (30 tubes of each material were studied). (9) As the surface of fluoroplastic tubes is smoother than the surface of silicone tubes, the irregular surface of the latter theoretically facilitates the development of bacterial adhesion and fouling. Also, stainless steel and titanium both have a theoretical advantage over both silicone and fluoroplastic in that they are associated with fewer manufacturing irregularities, and therefore they should be easier to unplug. However, neither of these theories was borne out by the findings of Tsao et al. (9) They found that with one exception, mucoid plugs cleared at approximately the same rate regardless of the type of material. The only significant difference was seen in the plug clearance rates of ion-bombarded silicone and untreated silicone; the former were cleared more quickly. Overall, Tsao et al concluded that tube composition does not significantly change the rate of mucoid plug dissolution ex vivo. (9)

Handler et al prospectively compared silicone tubes with gold-plated tubes and found that the gold tubes, which have a smoother surface, had a higher rate of extrusion; they also occluded more frequently. (12) In a separate study, these authors found no difference in extrusion rates and occlusion rates between titanium and silicone tubes. (13) Tami et al compared gold and polytetrafluoroethylene (Teflon) tubes and found a significantly higher rate of extrusion with the gold tubes; the rate of occlusion was also higher, but not significantly so. (14)

Biofilm was recently implicated in the formation of tympanostomy tube plugs. (15) The presence of biofilm may lead to the development of other dynamic factors in an in vivo situation that may play a role in tube plugging.

Prevention of plugged tubes

Several methods of preventing tube blockage have been attempted. In addition to using different tube materials, (9,11-14) investigators have tried to prevent occlusion by preoperative aspiration of middle ear effusion (not effective), (16) placement of a monofilament nylon suture into the lumen of the tube at the time of surgery (not effective), (17) and various perioperative medications. (18-22) Most of this research has involved the application of perioperative drugs:

* Cunningham and Harley performed a controlled study of 128 children who were undergoing bilateral tube placement. (18) They applied a coating of an antibiotic ointment to one tube prior to insertion and left the contralateral tube untreated. The incidence of obstruction by blood was lower in the treated tubes (2.3 vs. 4.7%), but the difference was not statistically significant.

* Jamal reported more dramatic differences in a controlled study of the vasoconstrictor xylometazoline vs. no treatment during tube placement. (19) Xylometazoline was administered to 60 ears in 32 patients; the control group was made up of 76 ears in 40 patients. At the 3-month follow-up, the incidence of tube blockage was 0 and 10.5%, respectively.

* Likewise, Altman et al found significant benefit in administering a vasoconstrictor perioperatively. (20) In a prospective, randomized, double-blind, controlled study of 310 ears undergoing tube placement, postoperative obstruction occurred in 2.3% of ears that had been treated with phenylephrine and antibiotics vs. 8.6% of ears that had been treated with antibiotics alone (p = 0.02). No ototoxicity was reported.

* Arya et al compared antibiotic/steroid therapy with no treatment in a randomized, double-blind study of blockage in 61 patients undergoing bilateral grommet insertion. (21) The incidence of tube obstruction in ears treated with dexamethasone 0.05%/framycetin 0.5%/gramicidin 0.005% (Sofradex) was 1.6%, compared with 13.1% for the untreated ears (p = 0.05). The authors did not find any association between tube blockage and either perioperative bleeding or the nature and presence of middle ear secretions.

* Finally, 122 respondents to a recent Internet survey conducted by the American Society of Pediatric Otolaryngology (ASPO) reported occlusion rates ranging from 0 to 9% following the perioperative administration of antibiotics only, antibiotic/steroid combinations, or decongestant drops. (22)

Treatment of plugged tubes

Tube blockage can be classified into two types: early and delayed. Early occlusion is usually caused by mucin and occasionally by bleeding. Delayed blockage occurs several months after tube placement, and it often develops secondary to accumulation of granulation tissue and wax.

The treatment of blocked tubes is largely empiric. Both mechanical means and ear drops have been used to dissolve plugs and restore patency:

* Mechanical clearance of a plug in a child in the office is difficult and often unsuccessful. (6) This procedure has the potential to cause significant discomfort and emotional trauma. Mechanical cleaning in the operating room has even more significant drawbacks. Therefore, the use of topical therapy remains the primary preventive and therapeutic option of choice.

* Brenman et al conducted a long-term retrospective study of 113 ears in 95 patients with occluded tubes. (3) They found that administration of hydrogen peroxide three times daily for 7 days opened 85% of these tubes. With respect to the ototoxic potential of this agent, 99% of these patients showed no immediate change in bone-conduction thresholds.

* Uppal et al performed a double-blind in vitro study of 473 blocked grommets to compare the efficacy of 5% sodium bicarbonate, 3% hydrogen peroxide, Sofradex, 0.33% acetic acid, and 0.9% sodium chloride drops. (6) The most efficacious was the 5% sodium bicarbonate, and the least efficacious was the 3% hydrogen peroxide.

* A very different finding was reported by Spraggs et al in their head-to-head comparison of sodium bicarbonate and hydrogen peroxide drops. (23) They found that the two drops were equally--and highly--effective.

* Westine et al compared the use of 12 solvents in a prospective nonblinded, nonrandomized in vitro study of 260 blocked tubes. (10) They found that both diluted vinegar and hyaluronidase solutions were significantly more likely to clear plugged tubes than were water and ototopical antibiotics; vinegar is preferred because it is known to be safer than hyaluronidase. Hyaluronidase is a mild exoglycosidase that cleaves hyaluronan polymers. These polymers make up cellular basement membranes. Hyaluronic acid moieties are also present in vitreous fluid, in saliva, and possibly in mucoid ear effusion. Also, it is interesting that in this study, 3% hydrogen peroxide did not fare well against the water control. However, the authors emphasized that their in vitro findings should be applied with caution because naturally occurring tube plugs in living models are likely to be more complex.

* Jassar et al conducted a randomized, controlled, double-blind in vitro comparison of sodium bicarbonate, flumetasone/clioquinol, and olive oil drops in 33 tubes each. (24) The drops were administered three times a day for 7 days. Although olive oil was significantly more effective than the other two solutions, it still cleared only 52% of the plugs.

* In the previously mentioned ASPO survey, most respondents reported that they treated occlusions by prescribing ear drops for home administration. (22) The most common drops were antibiotic/steroid combinations, antibiotics alone, and 1.5 and 3% hydrogen peroxide.

In conclusion, while there is no consensus on which specific agent to use, most physicians use topical drops to clear blocked tubes. Mechanical cleaning in the office or the operating room should be deferred for as long as possible, and replacement of a tube is a last resort.

References

(1.) Armstrong BW. A new treatment for chronic secretory otitis media. AMA Arch Otolaryngol 1954;59(6):653-4.

(2.) Vital and Health Statistics. Ambulatory and Inpatient Procedures in the United States, 1996. Series 13: Data from the National Health Care Survey No. 139. Publication No. (PHS) 99-1710. Hyattsville, Md.: U.S. Department of Health and Human Services; November 1998.

(3.) Brenman AK, Milner RM, Weller CR. Use of hydrogen peroxide to clear blocked ventilation tubes. Am J Otol 1986;7(1):47-50.

(4.) Kay DJ, Nelson M, Rosenfeld RM. Meta-analysis of tympanostomy tube sequelae. Otolaryngol Head Neck Surg 2001;124(4): 374-80.

(5.) MRC Multicentre Otitis Media Study Group. The role of ventilation tube status in the hearing levels in children managed for bilateral persistent otitis media with effusion. Clin Otolaryngol Allied Sci 2003;28(2):146-53.

(6.) Uppal S, Sharma R, Nadig SK, et al. A blinded in-vitro study to compare the efficacy of five topical ear drops in clearing grommets blocked with thick middle ear effusion fluid. Clin Otolaryngol 2005;30(1):29-34.

(7.) Reid AP, Proops DW, Smallman LA. Why do tympanostomy tubes block? Clin Otolaryngol Allied Sci 1998;13(4):279-83.

(8.) Westine JG, Giannoni CM, Antonelli PJ. Defining tympanostomy tube plugs. Laryngoscope 2002;112(6):951-4.

(9.) Tsao BA, Stevens GR, Antonelli PJ. Opening plugged tympanostomy tubes: Effect of tube composition. Otolaryngol Head Neck Surg 2003;128(6):870-4.

(10.) Westine JG, Giannoni CM, Gajewski B, Antonelli PJ. Opening plugged tympanostomy tubes. Laryngoscope 2002;112(8 Pt 1): 1342-5.

(11.) Berry JA, Biedlingmaier JF, Whelan PJ. In vitro resistance to bacterial biofilm formation on coated fluoroplastic tympanostomy tubes. Otolaryngol Head Neck Surg 2000;123(3):246-51.

(12.) Handler SD, Miller L, Potsic WP, et al. A controlled study of a "new" ventilating tube. The gold standard? Int J Pediatr Otorhinolaryngol 1986;12(1):33-8.

(13.) Handler SD, Miller L, Potsic WP, et al. A prospective study of titanium ventilation tubes. Int J Pediatr Otorhinolaryngol 1988;16(1): 55-60.

(14.) Tami TA, Kennedy KS, Harley E. A clinical evaluation of gold-plated tubes for middle-ear ventilation. Arch Otolaryngol Head Neck Surg 1987;113(9):979-80.

(15.) Kinnari TJ, Salonen EM, Jero J. New method for coating tympanostomy tubes to pre vent tube occlusions. Int J Pediatr Otorhinolaryngol 2001;58(2):107-11.

(16.) Laina V, Pothier DD. Should we aspirate middle-ear effusions prior to insertion of ventilation tubes? J Laryngol Otol 2006;120(10): 818-21.

(17.) Friedberg J. Removable ventilating tube obturator--how to save a ventilating tube. Int J Pediatr Otorhinolaryngol 1987;13(2):227-9.

(18.) Cunningham M J, Harley EH. Preventing perioperative obstruction of tympanostomy tubes: A postoperative trial of a simple method. Int J Pediatr Otorhinolaryngol 1991;21(1):15-20.

(19.) Jamal TS. Avoidance of postoperative blockage of ventilation tubes. Laryngoscope 1995;105(8 Pt 1):833-4.

(20.) Altman JS, Haupert MS, Hamaker RA, Belenky WM. Phenylephrine and the prevention of postoperative tympanostomy tube obstruction. Arch Otolaryngol Head Neck Surg 1998;124(11):1233-6.

(21.) Arya AK, Rea PA, Robinson PJ. The use of perioperative Sofradex eardrops in preventing tympanostomy tube blockage: A prospective double-blinded randomized-controlled trial. Clin Otolaryngol Allied Sci 2004;29(6):598-601.

(22.) Elden LM, Marsh RR. Survey of pediatric otolaryngologists: Clinical practice trends used to prevent and treat blocked ventilation ear tubes in children. Int J Pediatr Otorhinolaryngol 2006;70(9):1533-8.

(23.) Spraggs PD, Robinson PJ, Ryan R, et al. A prospective randomised trial of the use of sodium bicarbonate and hydrogen peroxide ear drops to clear a blocked tympanostomy tube. Int J Pediatr Otorhinolaryngol 1995;31(2-3):207-14.

(24.) Jassar R Jose J, Homer JJ. Otic drops used to clear a blocked grommet: An in vitro prospective randomized controlled study with blinded assessment. Clin Otolaryngol Allied Sci 2004;29(6):602-5.

Ramzi T. Younis, MD