Orbit, 2014; 33(4): 270–275 ! Informa Healthcare USA, Inc. ISSN: 0167-6830 print / 1744-5108 online DOI: 10.3109/01676830.2014.904377
RESEARCH REPORT
Learning Curve for use of the Sonopet Ultrasonic Aspirator in Endoscopic Dacryocystorhinostomy Michael C. Chappell1, Kris S. Moe2, and Shu-Hong Chang1 1
Division of Orbital and Ophthalmic Plastic Surgery, University of Washington Eye Institute, Seattle, Washington, USA, and 2Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington, USA
ABSTRACT Purpose: The Sonopet Ultrasonic Aspirator is a surgical tool that uses low-frequency ultrasonic vibrations to fragment tissue while simultaneously irrigating and aspirating the surgical field. This technology is becoming more widely used in orbital, lacrimal, neurological, and skull base surgery, but few studies have examined the learning curve associated with adoption of this technology. We present our surgical learning curve, pearls, and pitfalls using the newest generation Sonopet Ultrasonic Aspirator Universal handpiece in endoscopic dacryocystorhinostomy (eDCR) surgery. Methods: Retrospective chart review of consecutive eDCR surgeries performed by a single surgeon adopting the Sonopet Universal handpiece. Data collected include demographic information, indications for surgery, surgical time, intraoperative findings, anatomic and functional results, and complications. Results: Twenty-six eDCR surgeries in 20 patients were performed from October 2011 – May 2013. Most patients were female (85.7%) with mean age 53.6 years (range 4–84) and mean follow up of 378 days (range 7–761). For routine unilateral and bilateral surgeries, surgery time decreased by 36.4% and 33.9% before reaching a plateau of 67.2 and 80.7 minutes per case, respectively. Mean surgery time for non-sequential unilateral complex cases was 85.1 minutes, which did not vary significantly over the learning curve. We achieved 100% anatomic success and 84.6% functional success. Conclusions: The Sonopet Ultrasonic Aspirator Universal handpiece can be used safely and effectively for eDCR surgery. A significant learning curve exists for adoption of this technology. Appropriate handpiece tip selection and machine setting adjustments are crucial for successful adoption of this technology and avoidance of complications. Keywords: Dacryocystorhinostomy, DCR, sonopet, ultrasound
INTRODUCTION
In 2010, the Sonopet ‘‘Universal’’ handpiece was developed, which allows surgeons to use a single handpiece for both bone and soft tissue work simply by switching between various tips. The purpose of this study is to quantify our learning curve for adopting this newest version of Sonopet technology in eDCR surgery. We offer several recommendations for tip selection, avoidance of complications, and optimal utilization of this technology.
The Sonopet Ultrasonic Aspirator is a surgical tool that uses low-frequency ultrasonic vibrations to fragment tissue while simultaneously irrigating and aspirating the surgical field. Several studies have reported on the safe and efficacious use of the first generation Sonopet Omni in oculofacial plastic surgeries including external and endoscopic DCR as well as orbital decompression.1–4
Received 29 September 2013; Revised 3 March 2014; Accepted 10 March 2014; Published online 14 May 2014 Correspondence: Dr. Shu-Hong Chang, Division of Orbital and Ophthalmic Plastic Surgery, University of Washington Eye Institute, Box 359608, 325 Ninth Avenue, Seattle, WA, 98104, USA, Tel: 206-221-8538, Fax: 206-685-7055, E-mail: [email protected]
270
Learning Curve for SONOPET in Endoscopic DCR 271
MATERIALS AND METHODS The Sonopet Ultrasonic Aspirator consists of an ultrasonic handpiece that is connected to a base control module. Aspiration occurs through an opening at the distal aspect of the handpiece tip and irrigation fluid flows through a white irrigation sleeve surrounding the handpiece tip (Figure 1). The base module houses controls to regulate the irrigation rate, aspiration, and ultrasound power parameters of the machine. The unit is foot-pedal controlled. The Universal handpiece fits multiple interchangeable tips that have varying lengths, sizes, and shapes designed for specific soft tissue or bone removal purposes. The handpiece oscillates in a nonrotational fashion up to 25,000 times per second with a 0.36 mm width variation. The power setting is expressed as a percentage of that maximum. Aspiration reaches 500 mmHg and the aspiration setting on the machine is also expressed as a percentage of that maximum. The irrigation rate is expressed in milliliters per minute. University of Washington institutional review board approval was obtained for this retrospective chart review of consecutive eDCR surgeries performed by a single surgeon (SHC) adopting the Sonopet Universal Aspirator and its Universal handpiece. Prior to this study, SHC was experienced at performing eDCR using only rongeurs and chisels for bone removal. All surgeries were performed between October 2011 and May 2013. Data collected include demographic information, indications for surgery, operative time, intraoperative findings, anatomic and functional results, and complications.
Surgical Technique Following induction of general endotracheal anesthesia, the nasal mucosa at the surgical site was injected
with 1% lidocaine with 1:100,000 epinephrine followed by packing with oxymetazoline-soaked ¼’’ neurosurgical cottonoids. Injection of anesthetic constituted start of surgery as recorded for the purposes of this study. The patient was then prepped and draped in open-face sterile fashion. To integrate the Sonopet optimally into our surgical flow, we used it in conjunction with a foot pedal-controlled irrigating 30 endoscope. After removal of nasal packing, a Beaver blade was used to create a posteriorly based C-shaped incision in the nasal mucosa overlying the uncinate process. The nasal mucosa was reflected posteriorly using a Freer elevator. The Sonopet Universal handpiece with the long Spetzler Micro Claw tip was used to remove the bony encasement surrounding the lacrimal sac (Figure 1). After wide bony removal, the lacrimal sac was opened from superior to inferior pole using a Sickle blade. A ball-tipped probe was used to palpate the lumen of the sac, ensuring that no dead space remained at the apices of the sac. Bowman probes were inserted through the upper and lower canaliculi into the nasal space to ensure that no bony obstruction was encountered even with the probe tilted above and below the horizontal axis. If bony obstruction was encountered, the Sonopet was used to remove residual bone. Anterior and posterior relaxing incisions were made at each pole so that the lacrimal sac mucosa would flap open without obstruction. Manual pressure was applied to facilitate adhesion between the lacrimal sac and nasal mucosal flaps. Atrion selfretaining STENTubes were placed in every patient. Postoperatively, patients were asked to use steroid/ antibiotic eye drops 4 times daily for 1 week followed by twice daily for an additional week. During this 2-week period, patients also used fluticasone propionate nasal spray twice daily. In patients who returned for follow up, tubes were removed at 8–12 weeks postoperatively with immediate lacrimal irrigation to assess patency.
RESULTS
FIGURE 1. Long Spetzler Micro Claw tip showing the shape of the cutting surface and the aspiration opening at the distal end of the tip. !
2014 Informa Healthcare USA, Inc.
Twenty-six eDCR surgeries in 20 patients were performed from October 2011–May 2013. Most patients were female (85.7%) with mean age 53.6 years (range 4–84) and mean follow up of 378 days (range 7–761). Complete demographic data is shown in Table 1. For data analysis, cases were segregated into three groups: routine unilateral cases, routine bilateral cases, and complex cases. Complex cases were flagged at the time of surgery and included 3 revision cases with significant scarring requiring intraoperative mitomycin-C, 1 prior trauma, 2 prior sinonasal tumors, 2 cases with significant intraoperative hypertension and bleeding, and 4 cases
272 M. C. Chappell et al. TABLE 1. Demographic and outcomes.
Number of patients Number of eDCRs Age in years (mean, range) % female Ethnicity Caucasian Black Asian Hispanic Outcomes Anatomic success (%)y Functional success (%)z
TABLE 2. Surgery times for each case group.
All
Routine unilateral
Routine bilateral
Complex*
20
8
4
8
26
9
8
9
53.6, 4–84
57.9, 4–84
50, 7–73
51, 36–80
85.7
87.5
75
87.5
14 2 2 2
6 0 2 0
4 0 0 0
4 2 0 2
26
9
8
9
22
9
8
5
Surgery time (min)
Routine unilateral
Routine bilateral
Complex
p Value*
Mean Median Range
80 ± 20.2 69 63–113
91 ± 8.9 84.5 73–122
80.9 ± 21.6 84 47–100
0.558
*Analysis performed with one-way ANOVA test.
TABLE 3. Quartile analysis within case groups.
*Complex cases included 3 revision cases with significant scarring, 1 prior trauma, 2 prior sinonasal tumor, 2 cases with significant intraoperative hypertension and bleeding, 4 cases with unusually thick bone. yAnatomic success defined as patency on lacrimal irrigation at final postoperative visit. zFunctional success defined as patient report of resolution of epiphora.
with unusually thick bone. These complicating factors were not mutually exclusive. We achieved 100% anatomic success when assessed with postoperative lacrimal irrigation. Eighty-five percent (22/26) of cases resulted in functional success with patient-reported resolution of symptoms. The 3 patients (4 sides) with postoperative epiphora were all in the complex surgery group (Table 1). Notably, all 3 patients had longstanding sinonasal congestion and were subsequently referred to our otolaryngology colleagues for management of chronic sinonasal disease. Excluding 4 patients with fewer than 180 days follow-up, anatomic success was achieved in 100% of cases and functional success was achieved in 91% (20/22) of cases. No major complications were observed in this study. Our very first patient sustained a minor burn to the external skin of the nasal vestibule due to contact with an overheated irrigation sleeve. This complication is discussed in further detail. One-way ANOVA test was used to compare the mean operative times for each of the three patient groups (Table 2). These were not statistically different (p = 0.558). When the earliest quartile of cases were compared to the later cases within each group, however, it became clear that operative time decreased as surgeon and staff became more experienced (Table 3). For routine unilateral cases, mean surgery time in the first quartile of cases was 105.7 ± 11.8 minutes, compared to 67.2 ± 2.6 minutes in the remainder of cases. A two-sample t-test showed
Routine unilateral
Routine bilateral
Complex*
122 122 N/A
87 ± 4.2 87 84–90
Surgery time 1st quartile (min) Mean ± SD 105.7 ± 11.8 Median 112 Range 92–113
Surgery time remaining quartiles (min) Mean ± SD 67.2 ± 2.6 80.7 ± 4.3 Median 68.5 81 Range 63–69 73–88 p Valuey 0.015 N/A Learning curve (%)z 36.4 33.9
84.5 ± 10.2 84 70–100 0.326 3.4
*In quartile analysis for complex cases, the 47 minute outlier case was excluded from statistical analyses. yAnalysis performed with two-sample t-test. zLearning curve is expressed as % decrease in mean operative time between the earliest quartile of cases and the remainder of cases.
this was a statistically significant decrease (p = 0.015). A similar statistical analysis could not be performed for the routine bilateral cases due to small sample size. However, mean surgery time for routine unilateral and bilateral surgeries decreased by 36.4% and 33.9% before reaching a plateau average of 67.2 ± 2.6 and 80.7 ± 4.33 minutes per case, respectively. Quartile data analysis pertaining to non-sequential unilateral complex cases was performed after excluding a 47-minute outlier surgery. For the remaining 8 complex cases, mean surgery time in the first quartile of cases was 87 ± 4.2 minutes, compared to 84.5 ± 10.23 minutes in the remainder of cases. A two-sample t-test showed that this was not statistically significant (p = 0.326). Figure 2 demonstrates our surgical learning curve graphically.
DISCUSSION The learning curve associated with adoption of an ultrasonic surgical device has previously been studied in otological surgeons performing stapedotomy and tympanoplasty surgeries. In that study, Salami et al.5 found that operative time and length of hospital stay were approximately 30% longer in the initial tertile of cases performed by each surgeon compared to the latter cases. We present the first study of surgical learning curve during adaptation of ultrasound Orbit
Learning Curve for SONOPET in Endoscopic DCR 273
FIGURE 2. Scatterplot of chronological cases and operative time in minutes with linear regression line.
FIGURE 3. (A) Exposure of the lacrimal sac following bone removal using the Sonopet in a 9-year-old patient. (B) Lacrimal probe at the superior aspect of the opened lacrimal sac. Note the absence of bony obstruction at the superior most aspect of the lacrimal sac. Dots outline edge of bony ostium.
technology in lacrimal surgery. Our results corroborate those of Salami et al. Although it is possible to quantify surgical learning curve for a specific surgeon operating in a consistent environment, retrospective comparisons between surgeons at different institutions are difficult due to variability in surgeon technique as well as operating room staffing, efficiency, and recording of surgery time. For example, our study reported 67.2 minutes for routine unilateral eDCR surgery and approximately 81 minutes for complex unilateral or routine bilateral cases. Other studies have reported shorter average times for routine eDCR surgery, but do not specify whether mucosal flaps were created or whether anesthetic injection, prep, and draping were included in time measures.6,7 When multiple cases are performed sequentially during the same day, surgeon and staff familiarity with the equipment may bias results. We excluded !
2014 Informa Healthcare USA, Inc.
a 47-minute complex unilateral surgery from operative time analysis because that particular surgery was a second case performed sequentially on the same day as another complex case, which lasted 84 minutes. We believe that the main advantage conferred by the Sonopet technology is the increased efficiency and ease with which the superior-most pieces of bone encasing the lacrimal sac could be removed. With traditional rongeurs and chisels, this superior bone may be very difficult to remove because of the limited space and tight angulation within the nose. The long reach and small but adequate working area of the Sonopet allows this bone to be removed with ease and with minimal risk of surrounding tissue damage (Figure 3). When the Sonopet is used in conjunction with a foot-pedal controlled irrigating endoscope, it offers the additional advantage of minimizing instrumentation in and out of the nose.
274 M. C. Chappell et al.
FIGURE 4. Skin wound burn at postoperative week 1 (left) and wth complete resolution documented at postoperative month 3 (right).
Disadvantages of using the Sonopet in eDCR include cost and a steep learning curve. The machine and handpiece cost approximately $100,000 and $25,000 respectively. At a large academic institution, we enjoy the ability to cost-share with multiple other surgical services. Private ambulatory surgery centers may not have this option. An additional cost comes with the use of each single-use handpiece tip, which is approximately $350 for the long Spetzler Micro Claw tip. We offer some practical insights to shorten the learning curve for others who may be adopting the Sonopet technology in eDCR surgery.
Handpiece Tip Selection During the timeframe of this study, the available Universal handpiece bone tips were: regular and superlong Payner tips, long and superlong Spetzler Micro Claw tips, regular and superlong Spetzler Open Angle Micro Claw tips, and the Nakagawa Serrated Knife tip. After testing multiple bone tips in cadavers and live surgeries, our preferred tip for the Sonopet Ultrasonic Aspirator Universal handpiece in eDCR surgery is the long Spetzler Micro Claw tip (Figure 1). This tip has the appropriate length (4.6 inches) and angle for working in the lacrimal sac fossa, is small enough to permit optimal endoscopic endonasal visualization while still large enough to remove the bone efficiently, and does not have a 360 degree cutting surface that may traumatize nasal septal mucosa intraoperatively.
FIGURE 5. Straight Payner tip with melting of the white irrigation sleeve.
reach the surgical site, which compromises fluid flow to cool the tip and puts the plastic irrigation sleeve at risk of melting and transmitting heat to surrounding soft tissues (Figure 5). This is another reason that we prefer the angled long Spetzler Micro Claw tip. It is also important to set the irrigation rate at no less than 20 ml/min. This flow rate provides adequate irrigation of the operative field and and cools the handpiece tip without flooding the operative field. Ultrasound power and aspiration rate can remain safely at high levels (80–100%), as long as the irrigation rate is no less than 20 ml/min.
Suction and Machine Issues Avoidance of Wound Burn Excessive heat generation can cause wound burn if the fluidics of the Ultrasonic Aspirator are not optimized (Figure 4). Correct handpiece selection and attention to machine settings will help to avoid this complication. A straight tip carries a greater chance of wound burn because it requires the surgeon to push against one side of the irrigation sleeve to
Flooding of the operative field compromises endoscopic view and is most frequently due to obstruction along the suction tubing. The handpiece tips are packaged with a long thin wire, designed to be threaded through and to unclog any obstructions in the proximal areas of the handpiece tips (Figure 6). The distal aspect of the vacuum suction tubing should be connected to a non-basketed port in the suction Orbit
Learning Curve for SONOPET in Endoscopic DCR 275 become more adept with this technology. In our hands, patients experience a high anatomic and functional success rate comparable to those reported in the literature. Larger, prospective studies of eDCR learning curves in beginning versus experienced surgeons using various tools for bone removal would be useful for determining the best way to train physicians to perform eDCR surgery.
DECLARATION OF INTEREST
FIGURE 6. Plastic wire used to remove obstruction from handpiece tips.
The authors report no conflicts of interest and have no commercial relationship with any entity associated with Sonopet products. The authors alone are responsible for the content and writing of the paper.
REFERENCES
FIGURE 7. Vacuum canister lid showing suction port with attached basket. Connecting the Sonopet suction tubing in series with this basketed port may compromise intraoperative suction.
canister lid to optimize flow (Figure 7). Adequate suction allows better visualization and more efficient surgery. In conclusion, we now routinely use the Sonopet Ultrasonic Aspirator with its Universal handpiece and long Spetzler Micro Claw tip for eDCR surgery. Despite an initial steep learning curve, we have
!
2014 Informa Healthcare USA, Inc.
1. Sivak-Callcott JA, Linberg JV, Patel S. Ultrasonic bone removal with the Sonopet Omni: a new instrument for orbital and lacrimal surgery. Arch Ophthalmol 2005; 123(11):1595–1597. 2. Antisdel JL, Kadze MS, Sindwani R. Application of ultrasonic aspirators to endoscopic dacryocystorhinostomy. Otolaryngol Head Neck Surg 2008;139(4):586–588. 3. Murchison AP, Pribitkin EA, Rosen MR, Bilyk JR. The ultrasonic bone aspirator in transnasal endoscopic dacryocystorhinostomy. Ophthal Plast Reconstr Surg 2013; 29(1):25–29. 4. Cho RI, Choe CH, Elner VM. Ultrasonic bone removal versus high-speed burring for lateral orbital decompression: comparison of surgical outcomes for the treatment of thyroid eye disease. Ophthal Plast Reconstr Surg 2010; 26(2):83–87. 5. Salami A, Mora R, Mora F, et al. Learning curve for piezosurgery in well-trained otological surgeons. Otolaryngol Head Neck Surg 2010;142(1):120–125. 6. Hartikainen J, Antila J, Varpula M, et al. Prospectiverandomized comparison of endonasal endoscopic dacryocystorhinostomy and externaldacryocystorhinostomy. Laryngoscope 1998;108(12):1861–1866. 7. Malhotra R, Wright M, Olver JM. A consideration of the time taken to dodacryocystorhinostomy (DCR) surgery. Eye 2003;17:691–696.
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RESEARCH REPORT
Learning Curve for use of the Sonopet Ultrasonic Aspirator in Endoscopic Dacryocystorhinostomy Michael C. Chappell1, Kris S. Moe2, and Shu-Hong Chang1 1
Division of Orbital and Ophthalmic Plastic Surgery, University of Washington Eye Institute, Seattle, Washington, USA, and 2Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington, USA
ABSTRACT Purpose: The Sonopet Ultrasonic Aspirator is a surgical tool that uses low-frequency ultrasonic vibrations to fragment tissue while simultaneously irrigating and aspirating the surgical field. This technology is becoming more widely used in orbital, lacrimal, neurological, and skull base surgery, but few studies have examined the learning curve associated with adoption of this technology. We present our surgical learning curve, pearls, and pitfalls using the newest generation Sonopet Ultrasonic Aspirator Universal handpiece in endoscopic dacryocystorhinostomy (eDCR) surgery. Methods: Retrospective chart review of consecutive eDCR surgeries performed by a single surgeon adopting the Sonopet Universal handpiece. Data collected include demographic information, indications for surgery, surgical time, intraoperative findings, anatomic and functional results, and complications. Results: Twenty-six eDCR surgeries in 20 patients were performed from October 2011 – May 2013. Most patients were female (85.7%) with mean age 53.6 years (range 4–84) and mean follow up of 378 days (range 7–761). For routine unilateral and bilateral surgeries, surgery time decreased by 36.4% and 33.9% before reaching a plateau of 67.2 and 80.7 minutes per case, respectively. Mean surgery time for non-sequential unilateral complex cases was 85.1 minutes, which did not vary significantly over the learning curve. We achieved 100% anatomic success and 84.6% functional success. Conclusions: The Sonopet Ultrasonic Aspirator Universal handpiece can be used safely and effectively for eDCR surgery. A significant learning curve exists for adoption of this technology. Appropriate handpiece tip selection and machine setting adjustments are crucial for successful adoption of this technology and avoidance of complications. Keywords: Dacryocystorhinostomy, DCR, sonopet, ultrasound
INTRODUCTION
In 2010, the Sonopet ‘‘Universal’’ handpiece was developed, which allows surgeons to use a single handpiece for both bone and soft tissue work simply by switching between various tips. The purpose of this study is to quantify our learning curve for adopting this newest version of Sonopet technology in eDCR surgery. We offer several recommendations for tip selection, avoidance of complications, and optimal utilization of this technology.
The Sonopet Ultrasonic Aspirator is a surgical tool that uses low-frequency ultrasonic vibrations to fragment tissue while simultaneously irrigating and aspirating the surgical field. Several studies have reported on the safe and efficacious use of the first generation Sonopet Omni in oculofacial plastic surgeries including external and endoscopic DCR as well as orbital decompression.1–4
Received 29 September 2013; Revised 3 March 2014; Accepted 10 March 2014; Published online 14 May 2014 Correspondence: Dr. Shu-Hong Chang, Division of Orbital and Ophthalmic Plastic Surgery, University of Washington Eye Institute, Box 359608, 325 Ninth Avenue, Seattle, WA, 98104, USA, Tel: 206-221-8538, Fax: 206-685-7055, E-mail: [email protected]
270
Learning Curve for SONOPET in Endoscopic DCR 271
MATERIALS AND METHODS The Sonopet Ultrasonic Aspirator consists of an ultrasonic handpiece that is connected to a base control module. Aspiration occurs through an opening at the distal aspect of the handpiece tip and irrigation fluid flows through a white irrigation sleeve surrounding the handpiece tip (Figure 1). The base module houses controls to regulate the irrigation rate, aspiration, and ultrasound power parameters of the machine. The unit is foot-pedal controlled. The Universal handpiece fits multiple interchangeable tips that have varying lengths, sizes, and shapes designed for specific soft tissue or bone removal purposes. The handpiece oscillates in a nonrotational fashion up to 25,000 times per second with a 0.36 mm width variation. The power setting is expressed as a percentage of that maximum. Aspiration reaches 500 mmHg and the aspiration setting on the machine is also expressed as a percentage of that maximum. The irrigation rate is expressed in milliliters per minute. University of Washington institutional review board approval was obtained for this retrospective chart review of consecutive eDCR surgeries performed by a single surgeon (SHC) adopting the Sonopet Universal Aspirator and its Universal handpiece. Prior to this study, SHC was experienced at performing eDCR using only rongeurs and chisels for bone removal. All surgeries were performed between October 2011 and May 2013. Data collected include demographic information, indications for surgery, operative time, intraoperative findings, anatomic and functional results, and complications.
Surgical Technique Following induction of general endotracheal anesthesia, the nasal mucosa at the surgical site was injected
with 1% lidocaine with 1:100,000 epinephrine followed by packing with oxymetazoline-soaked ¼’’ neurosurgical cottonoids. Injection of anesthetic constituted start of surgery as recorded for the purposes of this study. The patient was then prepped and draped in open-face sterile fashion. To integrate the Sonopet optimally into our surgical flow, we used it in conjunction with a foot pedal-controlled irrigating 30 endoscope. After removal of nasal packing, a Beaver blade was used to create a posteriorly based C-shaped incision in the nasal mucosa overlying the uncinate process. The nasal mucosa was reflected posteriorly using a Freer elevator. The Sonopet Universal handpiece with the long Spetzler Micro Claw tip was used to remove the bony encasement surrounding the lacrimal sac (Figure 1). After wide bony removal, the lacrimal sac was opened from superior to inferior pole using a Sickle blade. A ball-tipped probe was used to palpate the lumen of the sac, ensuring that no dead space remained at the apices of the sac. Bowman probes were inserted through the upper and lower canaliculi into the nasal space to ensure that no bony obstruction was encountered even with the probe tilted above and below the horizontal axis. If bony obstruction was encountered, the Sonopet was used to remove residual bone. Anterior and posterior relaxing incisions were made at each pole so that the lacrimal sac mucosa would flap open without obstruction. Manual pressure was applied to facilitate adhesion between the lacrimal sac and nasal mucosal flaps. Atrion selfretaining STENTubes were placed in every patient. Postoperatively, patients were asked to use steroid/ antibiotic eye drops 4 times daily for 1 week followed by twice daily for an additional week. During this 2-week period, patients also used fluticasone propionate nasal spray twice daily. In patients who returned for follow up, tubes were removed at 8–12 weeks postoperatively with immediate lacrimal irrigation to assess patency.
RESULTS
FIGURE 1. Long Spetzler Micro Claw tip showing the shape of the cutting surface and the aspiration opening at the distal end of the tip. !
2014 Informa Healthcare USA, Inc.
Twenty-six eDCR surgeries in 20 patients were performed from October 2011–May 2013. Most patients were female (85.7%) with mean age 53.6 years (range 4–84) and mean follow up of 378 days (range 7–761). Complete demographic data is shown in Table 1. For data analysis, cases were segregated into three groups: routine unilateral cases, routine bilateral cases, and complex cases. Complex cases were flagged at the time of surgery and included 3 revision cases with significant scarring requiring intraoperative mitomycin-C, 1 prior trauma, 2 prior sinonasal tumors, 2 cases with significant intraoperative hypertension and bleeding, and 4 cases
272 M. C. Chappell et al. TABLE 1. Demographic and outcomes.
Number of patients Number of eDCRs Age in years (mean, range) % female Ethnicity Caucasian Black Asian Hispanic Outcomes Anatomic success (%)y Functional success (%)z
TABLE 2. Surgery times for each case group.
All
Routine unilateral
Routine bilateral
Complex*
20
8
4
8
26
9
8
9
53.6, 4–84
57.9, 4–84
50, 7–73
51, 36–80
85.7
87.5
75
87.5
14 2 2 2
6 0 2 0
4 0 0 0
4 2 0 2
26
9
8
9
22
9
8
5
Surgery time (min)
Routine unilateral
Routine bilateral
Complex
p Value*
Mean Median Range
80 ± 20.2 69 63–113
91 ± 8.9 84.5 73–122
80.9 ± 21.6 84 47–100
0.558
*Analysis performed with one-way ANOVA test.
TABLE 3. Quartile analysis within case groups.
*Complex cases included 3 revision cases with significant scarring, 1 prior trauma, 2 prior sinonasal tumor, 2 cases with significant intraoperative hypertension and bleeding, 4 cases with unusually thick bone. yAnatomic success defined as patency on lacrimal irrigation at final postoperative visit. zFunctional success defined as patient report of resolution of epiphora.
with unusually thick bone. These complicating factors were not mutually exclusive. We achieved 100% anatomic success when assessed with postoperative lacrimal irrigation. Eighty-five percent (22/26) of cases resulted in functional success with patient-reported resolution of symptoms. The 3 patients (4 sides) with postoperative epiphora were all in the complex surgery group (Table 1). Notably, all 3 patients had longstanding sinonasal congestion and were subsequently referred to our otolaryngology colleagues for management of chronic sinonasal disease. Excluding 4 patients with fewer than 180 days follow-up, anatomic success was achieved in 100% of cases and functional success was achieved in 91% (20/22) of cases. No major complications were observed in this study. Our very first patient sustained a minor burn to the external skin of the nasal vestibule due to contact with an overheated irrigation sleeve. This complication is discussed in further detail. One-way ANOVA test was used to compare the mean operative times for each of the three patient groups (Table 2). These were not statistically different (p = 0.558). When the earliest quartile of cases were compared to the later cases within each group, however, it became clear that operative time decreased as surgeon and staff became more experienced (Table 3). For routine unilateral cases, mean surgery time in the first quartile of cases was 105.7 ± 11.8 minutes, compared to 67.2 ± 2.6 minutes in the remainder of cases. A two-sample t-test showed
Routine unilateral
Routine bilateral
Complex*
122 122 N/A
87 ± 4.2 87 84–90
Surgery time 1st quartile (min) Mean ± SD 105.7 ± 11.8 Median 112 Range 92–113
Surgery time remaining quartiles (min) Mean ± SD 67.2 ± 2.6 80.7 ± 4.3 Median 68.5 81 Range 63–69 73–88 p Valuey 0.015 N/A Learning curve (%)z 36.4 33.9
84.5 ± 10.2 84 70–100 0.326 3.4
*In quartile analysis for complex cases, the 47 minute outlier case was excluded from statistical analyses. yAnalysis performed with two-sample t-test. zLearning curve is expressed as % decrease in mean operative time between the earliest quartile of cases and the remainder of cases.
this was a statistically significant decrease (p = 0.015). A similar statistical analysis could not be performed for the routine bilateral cases due to small sample size. However, mean surgery time for routine unilateral and bilateral surgeries decreased by 36.4% and 33.9% before reaching a plateau average of 67.2 ± 2.6 and 80.7 ± 4.33 minutes per case, respectively. Quartile data analysis pertaining to non-sequential unilateral complex cases was performed after excluding a 47-minute outlier surgery. For the remaining 8 complex cases, mean surgery time in the first quartile of cases was 87 ± 4.2 minutes, compared to 84.5 ± 10.23 minutes in the remainder of cases. A two-sample t-test showed that this was not statistically significant (p = 0.326). Figure 2 demonstrates our surgical learning curve graphically.
DISCUSSION The learning curve associated with adoption of an ultrasonic surgical device has previously been studied in otological surgeons performing stapedotomy and tympanoplasty surgeries. In that study, Salami et al.5 found that operative time and length of hospital stay were approximately 30% longer in the initial tertile of cases performed by each surgeon compared to the latter cases. We present the first study of surgical learning curve during adaptation of ultrasound Orbit
Learning Curve for SONOPET in Endoscopic DCR 273
FIGURE 2. Scatterplot of chronological cases and operative time in minutes with linear regression line.
FIGURE 3. (A) Exposure of the lacrimal sac following bone removal using the Sonopet in a 9-year-old patient. (B) Lacrimal probe at the superior aspect of the opened lacrimal sac. Note the absence of bony obstruction at the superior most aspect of the lacrimal sac. Dots outline edge of bony ostium.
technology in lacrimal surgery. Our results corroborate those of Salami et al. Although it is possible to quantify surgical learning curve for a specific surgeon operating in a consistent environment, retrospective comparisons between surgeons at different institutions are difficult due to variability in surgeon technique as well as operating room staffing, efficiency, and recording of surgery time. For example, our study reported 67.2 minutes for routine unilateral eDCR surgery and approximately 81 minutes for complex unilateral or routine bilateral cases. Other studies have reported shorter average times for routine eDCR surgery, but do not specify whether mucosal flaps were created or whether anesthetic injection, prep, and draping were included in time measures.6,7 When multiple cases are performed sequentially during the same day, surgeon and staff familiarity with the equipment may bias results. We excluded !
2014 Informa Healthcare USA, Inc.
a 47-minute complex unilateral surgery from operative time analysis because that particular surgery was a second case performed sequentially on the same day as another complex case, which lasted 84 minutes. We believe that the main advantage conferred by the Sonopet technology is the increased efficiency and ease with which the superior-most pieces of bone encasing the lacrimal sac could be removed. With traditional rongeurs and chisels, this superior bone may be very difficult to remove because of the limited space and tight angulation within the nose. The long reach and small but adequate working area of the Sonopet allows this bone to be removed with ease and with minimal risk of surrounding tissue damage (Figure 3). When the Sonopet is used in conjunction with a foot-pedal controlled irrigating endoscope, it offers the additional advantage of minimizing instrumentation in and out of the nose.
274 M. C. Chappell et al.
FIGURE 4. Skin wound burn at postoperative week 1 (left) and wth complete resolution documented at postoperative month 3 (right).
Disadvantages of using the Sonopet in eDCR include cost and a steep learning curve. The machine and handpiece cost approximately $100,000 and $25,000 respectively. At a large academic institution, we enjoy the ability to cost-share with multiple other surgical services. Private ambulatory surgery centers may not have this option. An additional cost comes with the use of each single-use handpiece tip, which is approximately $350 for the long Spetzler Micro Claw tip. We offer some practical insights to shorten the learning curve for others who may be adopting the Sonopet technology in eDCR surgery.
Handpiece Tip Selection During the timeframe of this study, the available Universal handpiece bone tips were: regular and superlong Payner tips, long and superlong Spetzler Micro Claw tips, regular and superlong Spetzler Open Angle Micro Claw tips, and the Nakagawa Serrated Knife tip. After testing multiple bone tips in cadavers and live surgeries, our preferred tip for the Sonopet Ultrasonic Aspirator Universal handpiece in eDCR surgery is the long Spetzler Micro Claw tip (Figure 1). This tip has the appropriate length (4.6 inches) and angle for working in the lacrimal sac fossa, is small enough to permit optimal endoscopic endonasal visualization while still large enough to remove the bone efficiently, and does not have a 360 degree cutting surface that may traumatize nasal septal mucosa intraoperatively.
FIGURE 5. Straight Payner tip with melting of the white irrigation sleeve.
reach the surgical site, which compromises fluid flow to cool the tip and puts the plastic irrigation sleeve at risk of melting and transmitting heat to surrounding soft tissues (Figure 5). This is another reason that we prefer the angled long Spetzler Micro Claw tip. It is also important to set the irrigation rate at no less than 20 ml/min. This flow rate provides adequate irrigation of the operative field and and cools the handpiece tip without flooding the operative field. Ultrasound power and aspiration rate can remain safely at high levels (80–100%), as long as the irrigation rate is no less than 20 ml/min.
Suction and Machine Issues Avoidance of Wound Burn Excessive heat generation can cause wound burn if the fluidics of the Ultrasonic Aspirator are not optimized (Figure 4). Correct handpiece selection and attention to machine settings will help to avoid this complication. A straight tip carries a greater chance of wound burn because it requires the surgeon to push against one side of the irrigation sleeve to
Flooding of the operative field compromises endoscopic view and is most frequently due to obstruction along the suction tubing. The handpiece tips are packaged with a long thin wire, designed to be threaded through and to unclog any obstructions in the proximal areas of the handpiece tips (Figure 6). The distal aspect of the vacuum suction tubing should be connected to a non-basketed port in the suction Orbit
Learning Curve for SONOPET in Endoscopic DCR 275 become more adept with this technology. In our hands, patients experience a high anatomic and functional success rate comparable to those reported in the literature. Larger, prospective studies of eDCR learning curves in beginning versus experienced surgeons using various tools for bone removal would be useful for determining the best way to train physicians to perform eDCR surgery.
DECLARATION OF INTEREST
FIGURE 6. Plastic wire used to remove obstruction from handpiece tips.
The authors report no conflicts of interest and have no commercial relationship with any entity associated with Sonopet products. The authors alone are responsible for the content and writing of the paper.
REFERENCES
FIGURE 7. Vacuum canister lid showing suction port with attached basket. Connecting the Sonopet suction tubing in series with this basketed port may compromise intraoperative suction.
canister lid to optimize flow (Figure 7). Adequate suction allows better visualization and more efficient surgery. In conclusion, we now routinely use the Sonopet Ultrasonic Aspirator with its Universal handpiece and long Spetzler Micro Claw tip for eDCR surgery. Despite an initial steep learning curve, we have
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2014 Informa Healthcare USA, Inc.
1. Sivak-Callcott JA, Linberg JV, Patel S. Ultrasonic bone removal with the Sonopet Omni: a new instrument for orbital and lacrimal surgery. Arch Ophthalmol 2005; 123(11):1595–1597. 2. Antisdel JL, Kadze MS, Sindwani R. Application of ultrasonic aspirators to endoscopic dacryocystorhinostomy. Otolaryngol Head Neck Surg 2008;139(4):586–588. 3. Murchison AP, Pribitkin EA, Rosen MR, Bilyk JR. The ultrasonic bone aspirator in transnasal endoscopic dacryocystorhinostomy. Ophthal Plast Reconstr Surg 2013; 29(1):25–29. 4. Cho RI, Choe CH, Elner VM. Ultrasonic bone removal versus high-speed burring for lateral orbital decompression: comparison of surgical outcomes for the treatment of thyroid eye disease. Ophthal Plast Reconstr Surg 2010; 26(2):83–87. 5. Salami A, Mora R, Mora F, et al. Learning curve for piezosurgery in well-trained otological surgeons. Otolaryngol Head Neck Surg 2010;142(1):120–125. 6. Hartikainen J, Antila J, Varpula M, et al. Prospectiverandomized comparison of endonasal endoscopic dacryocystorhinostomy and externaldacryocystorhinostomy. Laryngoscope 1998;108(12):1861–1866. 7. Malhotra R, Wright M, Olver JM. A consideration of the time taken to dodacryocystorhinostomy (DCR) surgery. Eye 2003;17:691–696.
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