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Tonsillectomy by Means of Plasma-Mediated Ablation
Prospective, Randomized, Blinded Comparison With Monopolar Electrosurgery
Udayan K. Shah, MD;
Jeffrey Galinkin, MD;
Rosetta Chiavacci, RN, BSN;
Marianne Briggs, RN, MSN, CRNP
Arch Otolaryngol Head Neck Surg. 2002;128:672-676.
ABSTRACT
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Objective To compare plasma-mediated ablation (PMA) with monopolar electrosurgery
(MES) for pediatric tonsillectomy.
Design Prospective, randomized, blinded study.
Setting Academic children's hospital.
Participants Thirty-four children, aged 4 to 7 years.
Interventions Tonsillectomy by means of PMA (n = 17) or MES (n = 17).
Outcome Measures We measured surgical efficacy, estimated blood loss, and surgical time
during tonsillectomy and morphine use, immediate postoperative pain, and recovery
scores after tonsillectomy. Parents recorded recovery of normal diet and activity
and their own return to work for 10 days after surgery. Histopathologic evaluation
of excised tonsils was performed. We reviewed medical records and attempted
follow-up telephone contact.
Results With no significant difference in blood loss compared with MES, PMA
was effective for tonsillectomy. Performance of PMA took longer (24 vs 16
minutes; P = .002). Results of histopathologic evaluation
showed less thermal injury with PMA than with MES (P
= .03). Morphine consumption, pain, and recovery scores were equivalent between
groups. We found no significant difference in recovery of normal diet and
activity or parental return to work. Patients undergoing PMA had a greater
number of perioperative complications than those undergoing MES, including
2 patients in the PMA group (compared with none in the MES group) who required
unplanned admission for postoperative airway obstruction.
Conclusions Plasma-mediated ablation for pediatric tonsillectomy resulted in less
histopathologic thermal injury than MES, but did not show a statistically
faster recovery to normal activity and diet or parental return to work. In
addition, PMA took longer to perform, and had more complications. Therefore,
PMA should not replace MES for pediatric tonsillectomy. The reduced thermal
injury with PMA supports investigation into other means of using plasma ablation
to treat tonsillar hypertrophy.
INTRODUCTION
TONSILLECTOMY IN children is most often performed today using monopolar
electrosurgery (MES) or cold instruments (knife or scissors). Electrocautery
is favored for its hemostasis,1 whereas advocates
of cold tonsillectomy believe that reduced thermal injury to the pharynx results
in less postoperative pain.2
Monopolar electrosurgery excises tissue by using radiofrequency current
to burn soft tissue. Plasma-mediated ablation (PMA) energizes protons to break
molecular bonds between tissues. Tissue removal using PMA leaves less heat
in tissue, and so reduces thermal injury.3-4
This reduced thermal effect with PMA has resulted in the term cold ablation or Coblation (ArthroCare Corp,
Sunnyvale, Calif). Plasma-mediated ablation has been offered for tonsillectomy
since 1998 as a means of creating less thermal injury than that seen with
MES, while achieving better hemostasis than with cold instruments alone.
Our previous experience in children showed that PMA was effective for
tonsillectomy to treat lymphoid hyperplasia in children older than 3 years,5 with reduced gross and histopathologic thermal damage
and less ability to provide hemostasis than that seen with MES.4
Despite these promising initial results, no evidence to date supports the
claim that reduced thermal injury translates into improved outcomes for children
and families.
We undertook this investigation to determine the efficacy, benefits,
and risks of performing pediatric tonsillectomy by means of PMA compared with
tonsillectomy by our standard means of MES.
PATIENTS AND METHODS
We recruited children aged 4 through 7 years, who were scheduled for
day-surgery adenotonsillectomy (T&A) to treat adenotonsillar hypertrophy,
from August 10, 1999, through April 26, 2000. Parents provided informed consent.
Children 3 years and younger were excluded because of their higher risk for
perioperative complications,6 severe obstructive
sleep apnea, craniofacial syndrome, developmental delay, expressive language
disorder, hematologic wound-healing disorder or necrotizing dermatosis, implanted
electrical device, and mucopolysaccharidosis. Parents and patients were unaware
of the surgical technique.
The primary outcome measure was the score on the Bieri Faces Pain Scale.
Because sample size calculation is not straightforward for noncontinuous measures,
various scenarios were tested. The most optimistic yielded a P value of .008 and the most pessimistic, a P
value of .05 for a sample size of 30 control subjects and 30 children in the
experimental group.
Prospective randomization determined whether PMA or MES was used for
tonsillectomy. Adenotonsillectomy was performed under a standardized regimen
of general anesthesia. After adenoidectomy by means of curette, tonsillectomy
was performed by means of MES, using an electrocautery pencil (Valleylab,
Boulder, Colo), or by means of PMA, using the ArthroWand (ArthroCare Corp).
Hemostasis after excision was achieved by means of suction electrocautery
for both groups. Intravenous antibiotics and dexamethasone sodium phosphate
(dose determined by body weight) were administered.
We measured time to perform T&A and estimated blood loss. The surgeon
assessed PMA for ease of use, ability to excise tissue, and hemostasis. Randomly
selected tonsils were sent from both groups for histopathologic evaluation
by a pathologist masked to surgical technique.
A standardized medication regimen was administered in the postanesthesia
care unit by nurses masked to the surgical technique. Use of morphine sulfate
was recorded. Nurses rated pain using the Bieri Faces scale, a visual analog
scale intended for children aged 3 to 7 years.7-8
Pain was scored at 15-, 30-, and 60-minute intervals. Steward scores, measuring
readiness for discharge, tracked consciousness, airway patency, and ability
to move.9 Nurses recorded scores at 30 and
60 minutes.
Parents were asked to record postoperative progress on a checklist,
tracking return to normal activity and diet and parental return to work. Parents
scored activity (1, none; 2, very little; 3, mostly normal and 4, normal),
diet (1, liquids and soft diet only; 2, some solids; 3, mostly solids; and
4, normal diet), and commented on missed work (yes, no, and would not have
worked anyway [with separate responses for father and mother]). Medical records
were reviewed for complications, and telephone follow-up was attempted. The
study was to be stopped if significantly more postoperative hemorrhages required
reoperation in the PMA group than the 2.7% that is typical at this institution.
The Institutional Review Board of The Children's Hospital of Philadelphia,
Philadelphia, Pa, approved this study. Unless otherwise indicated, data are
given as mean ± SD.
RESULTS
We enrolled 34 children undergoing tonsillectomy: 17 by means of MES,
and 17 by means of PMA. Average age of the 9 girls and 8 boys in the MES group
was 5.4 years; of the 6 girls and 11 boys in the PMA group, 5.2 years. The
MES group averaged 22.2 kg in weight; the PMA group, 21.7 kg. Because of 2
airway complications in the PMA group, one of us (U.K.S.) chose to terminate
the study at 34 patients, rather than to complete enrollment to 60 patients.
Tonsillectomy in all cases was possible with PMA. Subjectively, ease
of use and hemostasis were equivalent for MES and PMA. Hemostasis with PMA
was possible for vessels less than 1 mm in diameter. One important finding,
confirming previous experience, is that the plasma wand ablated 2 to 3 mm
in advance of the instrument tip. The ability to excise tissue was subjectively
rated better with PMA (P<.02).
Mean surgical time was 16.2 ± 3.2 minutes for MES and 23.8 ±
7.9 minutes for PMA. This difference was statistically significant (P = .002). Surgical time for patients in the PMA group
for whom ability to provide hemostasis was subjectively assessed as similar
to MES was an average of 20.9 minutes, compared with an average of 25.7 minutes
for patients with less hemostasis. This difference in time approached statistical
significance (P = .05). Mean estimated blood loss
was 83.8 ± 46.4 mL for the MES group and 90.9 ± 35.3 mL for
the PMA group (P = .51) (Table 1).
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Table 1. Operative Measures*
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Results of histopathologic evaluation showed that 4 tonsils from the
MES group had a mean depth of injury of 0.63 ± 0.25 mm. In contrast,
3 tonsils from the PMA group showed a mean depth of injury of 0.13 ±
0.12 mm. These differences were statistically significant (t = 3.11; P = .03) (Figure 1).
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Figure 1. Difference in thermal effect by
histopathologic evaluation of tonsillectomy by means of plasma-mediated ablation
(PMA) vs monopolar electrosurgery (MES). Tonsils, randomly selected from each
group, underwent histopathologic evaluation (hematoxylin-eosin, original magnification
x40). A, Specimen excised by means of MES. At the excision margin to
the left of this image, tissue charring and basophilic infiltrate are seen.
B, In contrast, the tonsil excised by means of PMA shows almost no basophilic
infiltrate at the margin or any charring of the tissue. Tonsils from patients
in the PMA group showed less thermal damage (P= .03).
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Total morphine consumption and the Faces and Steward scores were not
significantly different between the MES and PMA groups (Table 2).
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Table 2. Recovery Measures*
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Complications were seen in 2 patients after MES, related to hydration
in both. Four children had perioperative complications after PMA. Two children
required postoperative admission for airway obstruction; both required supplemental
oxygen, and 1 required a nasal airway. The third child required readmission
for dehydration, and the fourth experienced a delayed posttonsillectomy hemorrhage
that was managed surgically.
The families of patients in the MES and PMA groups returned 8 (47%)
of 17 forms from each group. No statistically significant difference in recovery
of diet, activity, or parental return to work was seen (Figure 2,
Figure 3, and
Figure 4).
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Figure 2. Return to normal diet. The difference
seen, in recovery of diet after tonsillectomy by means of monopolar electrosurgery
(MES) vs plasma-mediated ablation (PMA), as reported by parents, was not statistically
significant. Scores are described in the "Patients and Methods" section.
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Figure 3. Return to normal activity. The
difference seen in recovery of activity after tonsillectomy by means of monopolar
electrosurgery (MES) vs plasma-mediated ablation (PMA), as reported by parents,
was not statistically significant. Scores are described in the "Patients and
Methods" section.
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Figure 4. Parents who lost days from work.
Nearly all parents who worked could not do so on the day of surgery. By the
end of the first week, most parents could return to work if needed. The differences
seen between children who had tonsillectomy performed by means of monopolar
electrosurgery (MES) vs plasma-mediated ablation (PMA) was not statistically
significant.
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Responses of diet scores show that on average, children in the PMA group
did better than those in the MES group after day 3. The first day at which
diet for more than half of the respondents was mostly normal or normal was
not seen during the 10 days of responses for the MES group, whereas it was
seen at 7 days for the PMA group. These differences were not statistically
significant.
Graphs of averaged activity scores show children in the PMA group with
higher average activity scores after day 7 compared with those in the MES
group. The first day at which activity for more than half of the children
was mostly normal or normal was 10 days for the MES group and 8 days for the
PMA group.
Nearly all parents missed work on the day of surgery. By the end of
the first week, most parents could return to work if needed (Figure 4).
Twelve (71%) of 17 patients in each group were reached by telephone
for follow-up at an average of 178 days. One child in the MES group complained
of persistent snoring. Three children in the PMA group (3/17 [18%]) each had
1 of the following complaints: velopharyngeal insufficiency, drooling and
poor speech clarity, and 2 episodes of pharyngitis after tonsillectomy.
COMMENT
The plethora of techniques applied for tonsillectomy argues against
the clear superiority of any single method. In the first century AD, Celsus
removed diseased tonsils using blunt finger dissection or a sharp hook and
knife. The fauces were then "washed out with vinegar and painted with a medication
to reduce bleeding."10 From the mid-19th century
until the earlier part of the 20th century, a knife, dissectors, scissors,
a tonsillotome, or a guillotine was used for the sharp, complete (tonsillectomy)
or partial (tonsillotomy) removal of the tonsils,10-11
with the patient awake or under local anesthesia, or anesthetized with ether.
Hemostasis was achieved by means of gargling or painting the fauces with medications.
The significant improvements in general anesthesia seen in the 20th century
allowed surgeons to perform tonsillectomy with careful dissection and to secure
hemostasis with ties, sutures, or ligatures.10, 12
Today, most tonsillectomy is performed using cold instruments (ie, knife,
scissors, dissectors, or snare) or hot excision (using electrocautery), with
hemostasis by suture or ligature or by electrocautery. Although proponents
of cold tonsillectomy expect a less painful recovery, hot dissection is advocated
for faster excision and less intraoperative bleeding.1
The retelling by Catlin10 of Samuel Crowe's
experience with tonsillar cauterization provides a memorable, if extreme,
example of the problems with hot techniques:
Dr Crowe . . . developed a persistent sore throat and sought
the advice of William Halstead. . . . Tuberculosis of the tonsils was diagnosed
and cauterization was recommended. . . . While [Crowe] was being put to sleep
with ether, an assistant heated a large soldering iron over a blow torch .
. . at the appropriate moment, Halstead . . . approached the mouth [with the
iron, and] there was a flash of blue flame and the procedure was abruptly
terminated. . . . Crowe sustained thermal burns of the mouth as well as the
ether explosion. When he awakened, Crowe confided that he felt as if he was
cauterized all over. "I knew that something was wrong," he said, "Because
Halstead came to see me every day. Halstead never saw a postoperative patient
if he could avoid it!"
We have investigated PMA for tonsillectomy since 1998, when it was offered
as a means of bridging the gap between cold and hot techniques. Plasma-mediated
ablation promised better hemostasis with excision than cold methods, while
leaving less heat to the pharynx than MES.4-5
We compared PMA with MES, our standard technique for tonsillectomy,
to determine whether PMA in vivo would demonstrate less histopathologic thermal
injury, and whether this reduced thermal injury was sufficient to result in
a faster, less painful recovery. We used a randomized, prospective, partially
blinded protocol. This report of 34 patients is the largest prospective series
comparing MES and PMA to date. This series showed that PMA was effective for
tonsillectomy and demonstrated less histopathologic thermal injury, but that
PMA took longer to perform and did not offer statistically significant improvement
in recovery for children or families compared with MES.
Tonsillectomy was possible in all cases with PMA, which was believed
to allow better excision than MES, and was equivalent to MES for ease of use
and hemostasis. Plasma-mediated ablation required on average of 7.6 minutes
longer than MES (Table 1). Surgical
inexperience cannot be blamed, as the learning curve was broached during previous
work by the same surgeon. The longer surgical time most likely did not relate
to reduced hemostasis of PMA, as hemostasis (subjectively) and recorded estimated
blood loss were equivalent. For those cases in which PMA resulted in worse
hemostasis than would have been expected with MES, however, surgical times
were longer, with near statistical significance (P
= .05). Most likely, the longer surgical time of PMA relates to instrumentation
and technique. Extra irrigation and tubing is required for water delivery
for PMA. The time difference of more than 30% may also reflect the greater
care required during tonsillectomy with PMA to avoid lateral injury due to
the 2- to 3-mm zone of ablation in front of the tip of the plasma wand. Appropriate
use of the instrument, in our experience to date, has been without significant
problems.
This study confirmed the anticipated reduction in histopathologic thermal
injury with PMA compared with MES (Figure
1). Tonsils excised by means of PMA showed only a 0.13-mm depth
of histopathologic thermal injury on average, compared with those excised
by means of MES, which showed 0.63-mm damage. This difference was statistically
significant even for this small sample (P = .03).
This reduced thermal effect, however, did not translate into improved recovery.
We found no statistically significant difference between groups for morphine
consumption in the postanesthesia care unit, the Bieri Faces scale (a visual
analog pain scale), and predischarge Steward scores (to evaluate readiness
for discharge) (Table 2). Once
home, the return to normal diet and activity and parental return to work were
similar between groups (Figure 2, Figure 3, and Figure 4). The self-reporting format had a poor response rate, with
less than half of each group returning surveys. Although the PMA group showed
an earlier return to mostly normal or normal activity and diet, this difference
was not statistically significant. An important message from these responses
is the lack of complete recovery even at 10 days after surgery, supporting
outcomes measures that track recovery for up to 2 weeks.2, 13
The PMA group had a trend to a higher complication rate, including 2
children with airway edema. The airway edema may be due to PMA-related thermal
injury, but this is contrary to the reduced thermal injury seen histopathologically.
Sealing of lymphatic channels, or an as yet uncharacterized tissue effect
of PMA, may be to blame. The airway edema may simply reflect the longer surgical
time of PMA. Although our sample size was too small to allow statistical characterization
of airway risk due to T&A with PMA, the unplanned admission of 2 children
from the PMA group is cause for concern. This study was terminated before
complete enrollment because of these airway complications.
The lack of a statistically significant improvement in perioperative
measures despite reduced histopathologic thermal injury, and in fact a trend
to a higher rate of complications, has several explanations. First, the use
of electrocautery to achieve hemostasis after PMA excision of tonsils may
undo the benefits of cooler ablation. The advocates of cold tonsillectomy
would recommend a controlled trial with PMA for T&A followed by the use
of sutures or ligatures for hemostasis, compared with MES or a knife or scissors
for excision. Second, although the histopathologic evaluation of thermal injury
is considered to be a proxy for presumed thermal injury to the pharynx, this
thermal effect on the excised tonsil may not be important to recovery. Third,
a yet undefined tissue effect, unique to PMA, might cause neural irritation,
or other soft tissue trauma, of which the airway edema seen in 2 children
after PMA may be a harbinger.
One extension of this work may be to treat tonsillar hypertrophy by
means of delivery techniques other than the plasma wand, and to offer tonsillar
reduction (tonsillotomy) rather than resection (tonsillectomy). This concept
is particularly valid if pain is due to exposed pharyngeal musculature. Reduction
of tonsillar tissue may be possible by laser techniques14
or by different delivery systems for PMA. In addition to reduced pain, these
methods offer a reduced risk for immediate and delayed postoperative hemorrhage.
These methods have not yet been fully investigated in children, and to date,
no long-term evaluation of tonsillar regrowth has been performed for these
alternatives.
Regardless of the tonsillectomy technique studied, we offer this study
as a means of facilitating as objective an analysis as possible of the many
factors involved in evaluating new technologies for tonsillectomy in children.
Technical factors, tissue effects, perioperative pain scores and medication
use, and recovery variables are all important in considering various techniques
for this commonly performed surgery.
CONCLUSIONS
Plasma-mediated ablation for pediatric tonsillectomy resulted in less
histopathologic thermal injury than MES, but did not show a statistically
faster recovery to normal activity and diet or parental return to work. In
addition, PMA took longer to perform (P = .002) and
showed a trend to more complications. This technique as it is presently delivered
should not replace MES for routine tonsillectomy. The reduced thermal injury
seen with PMA, however, supports current investigations into other means of
using PMA to treat tonsillar hypertrophy in children.
AUTHOR INFORMATION
Accepted for publication October 30, 2001.
This study was supported in part by Public Health Services Research
grant MO1RR-00240 from the National Institutes of Health, Bethesda, Md.
This study was presented at the 16th Annual Meeting of the American
Society for Pediatric Otolaryngology, Scottsdale, Ariz, May 11, 2001.
We thank Bruce Pawel, MD, Department of Pathology and Laboratory Medicine,
The Children's Hospital of Philadelphia, for providing insights and histopathologic
evaluations. Equipment for plasma-mediated ablation was generously provided
by the ENTec Division of the ArthroCare Corporation, Sunnyvale, Calif.
Corresponding author: Udayan K. Shah, MD, Pediatric Otolaryngology,
The Children's Hospital of Philadelphia, Wood Center, First Floor, 34th Street
and Civic Center Boulevard, Philadelphia, PA 19104-4399 (e-mail: shah{at}email.chop.edu).
From the Divisions of Otolaryngology (Dr Shah and Ms Briggs) and Anesthesiology
and Critical Care (Dr Galinkin and Ms Chiavacci), The Children's Hospital
of Philadelphia, and the Department of Otorhinolaryngology–Head and
Neck Surgery, University of Pennsylvania School of Medicine (Dr Shah and Ms
Briggs), Philadelphia, Pa.
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