World J Surg DOI 10.1007/s00268-015-2995-7
ORIGINAL SCIENTIFIC REPORT
A Prospective Randomized Controlled Trial of the Laryngeal Mask Airway Versus the Endotracheal Intubation in the Thyroid Surgery: Evaluation of Postoperative Voice, and Laryngopharyngeal Symptom Byung-Joon Chun • Ja-Sung Bae • So-Hui Lee Jin Joo • Eun-Sung Kim • Dong-Il Sun
•
Ó Socie´te´ Internationale de Chirurgie 2015
Abstract Background The present study was performed to determine whether thyroidectomy patients undergoing general anesthesia provided with a laryngeal mask airway (LMA) have a lower risk of voice-related complications and laryngopharyngeal symptoms than those undergoing endotracheal intubation (ETI). Materials and methods In a prospective, double-blinded, randomized clinical trial, we studied 64 patients undergoing elective thyroid lobectomy between July 2013 and February 2014. Acoustic analyses were performed preoperatively and at 48 h and 2 weeks postoperatively. The voice handicap index (VHI), M.D. Anderson dysphagia index (MDADI), and laryngopharyngeal symptom score (LPS) were determined preoperatively and at 24 h, 48 h, 1 week, and 2 weeks post-thyroidectomy. Results In acoustic analysis, jitter, shimmer and noise-to-harmonic ratio showed significantly better results in the LMA group than the ETI group 48 h after surgery, but there was no difference at 2 weeks. The incidence of postoperative lower-pitched voice in the LMA group was also significantly lower than that in the ETI group. In the LMA group, the VHI, MDADI, and LPS were better compared to those in the ETI group at 24 h postoperatively, and improved to the preoperative state within 1 week. However, those in the ETI group remained poorer than the preoperative values 1 week after surgery. Conclusions Use of the LMA in general anesthesia for thyroid surgery has advantages over the ETI in decreasing patients’ subjective and objective voice symptoms, reducing the duration of symptoms, and relieving the laryngopharyngeal symptoms.
B.-J. Chun D.-I. Sun (&) Department of Otorhinolaryngology-Head and Neck Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea e-mail: [email protected] J.-S. Bae S.-H. Lee Department of Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea J. Joo E.-S. Kim Department of Anesthesiology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
Introduction Thyroid disease has a high prevalence in the general population, particularly in females [1]. Thyroidectomy is a frequently used surgical procedure to treat thyroid disease, and vocal dysfunction is the most likely complication of this procedure. There have been many reports that patients undergoing thyroidectomy developed voice dysfunction postoperatively [1–4]. One report indicated that the voice change after thyroidectomy without any evident laryngeal injury shows typical characteristics, such as voice fatigue and difficulty making higher pitched sounds, hoarseness, low voice, and weak voice [5]. There are several possible
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causes of post-thyroidectomy voice dysfunction without laryngeal nerve injury. First, surgical manipulation and disturbed vascularization may cause nerve dysfunction. Second, the strap muscles that play an important regulatory function in phonation may be divided and damaged, which can lead to changes in tension and motility of the internal and external laryngeal muscles. Removal of the thyroid gland modifies the vascular supply and venous drainage of the larynx. Together with endotracheal intubation (ETI), this may cause alterations in the mucosa as slight congestion, which may in part explain the lower-pitched voice [6]. The incidence of side effects (laryngeal pain, hoarseness, dysphonia) related to ETI in the early postoperative period ranges from 15 to 50 % [7–10]. Several reports have identified risk factors for laryngeal morbidity following tracheal intubation including endotracheal tube size, cuff design, and cuff pressure [8–11]. The laryngeal mask airway (LMA) is an alternative to ETI for controlling the upper airway and permitting mechanical ventilation, and use of the LMA may decrease the risk of laryngeal trauma. In previous studies, the incidences of postoperative sore throat and hoarseness were significantly higher in patients treated using the ETI compared to those using LMA [12, 13]. Several studies have indicated the usefulness of LMA in thyroid surgery [14, 15]. However, there have been few comparisons of the objective acoustic parameters of voice dysfunction between anesthesia with LMA and ETI in thyroid surgery. Therefore, the present study was performed to compare the postoperative acoustic parameters, subjective vocal and swallowing function, and laryngopharyngeal symptoms between ETI and LMA during thyroidectomy.
Materials and methods Study design A prospective, double-blind, randomized clinical trial was performed to evaluate the usefulness of the LMA compared to ETI by analyzing changes in clinical symptoms and acoustic parameters before and after surgery. The Institutional Review Board of the Office of Human Research Protection at Catholic Medical Center, Seoul, Korea approved the study. Patients The study population consisted of 64 patients treated between July 2013 and February 2014. Written informed consent was obtained from each patient during the preoperative visit. We selected single papillary thyroid
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carcinoma (\1 cm) patients to minimize surgical factors for patients’ voice and swallowing symptoms. All patients underwent thyroid lobectomy without central node dissection by one surgeon in our Department of Surgery and were referred to our Department of Otolaryngology/Headand-Neck Surgery for pre- and postoperative voice evaluation. We used fiberoptic laryngoscopy (Machida Instruments, Tokyo, Japan) and videolaryngostroboscopy (model 9200C; KayPENTAX, Lincoln Park, NJ, USA) to examine the larynx at the pre- and postoperative period. Exclusion criteria were as follows: previous neck surgery or revision thyroidectomy; preoperative laryngeal disorder, such as vocal nodules, vocal polyps, or vocal cord paralysis; dental or upper airway infection; or expected duration of surgery [2 h. Patients with criteria of difficult intubation (mouth opening \35 mm, thyromental distance \60 mm, Mallampati grade [3) were also excluded from the study. Patients were randomized into one of two groups using a coded, opaque, sealed envelope technique. Allocation was performed in the operating room just before induction of anesthesia. The general anesthesia was performed by one skilled anesthesiology physician. No premedication was administered to the patients. Electrocardiogram, noninvasive blood pressure, heart rate, and pulse oximetry were measured continuously at 5-min intervals, starting at the time of arrival in the operating room. General anesthesia was induced with 2 mg/kg propofol and 0.6 mg/kg rocuronium. When patients were fully sedated and relaxed, endotracheal tube (MallinckrodtÒ 6.5–7.5; Covidien, Dublin, Ireland) was in the ETI group, and LMA FlexibleTM (size 3–5 according to the patient’s weight; Teleflex, Dublin, Ireland) was inserted in the LMA group. Anesthesia was maintained with 1.5–2 vol.% sevoflurane, medical air in oxygen [fraction of inspired O2 (FiO2) = 0.5], and continuously infused IV remifentanil 0.05–0.1 lg/kg/min, keeping end-tidal CO2 between 35 and 40 mmHg throughout the surgery. Ringer’s lactate solution was administered at 6–8 ml/kg/h during surgery. When ventilation difficulty occurred during tracheal manipulation, the anaesthetist immediately reported the surgeon, and the trachea was handled with care. At the end of the surgical procedure, sevoflurane and remifentanil administration were discontinued. IV 0.2 mg/kg pyridostigmine and 0.008 mg/kg glycopyrrolate were administered for reversal of muscle relaxation. The trachea was extubated in the ETI group and the LMA FlexibleTM was removed in the LMA group when spontaneous respiration of the patient was adequate. Acoustic analysis All patients were instructed to pronounce the vowel /a/ at a comfortable volume and constant pitch. Each vowel
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pronunciation was recorded with a constant mouth-tomicrophone distance of 5 cm using the Computerized Speech Lab (model 4150; KayPENTAX, Montvale, NJ). All digital recordings were made in a soundproofed room. Each
patient sustained an /a/ for at least 3 s at a comfortable pitch level. The task was repeated at least four times, and the fourth trial was often the recorded sample. Each analysis was performed using a multidimensional voice program (model
Table 1 Laryngopharyngeal symptom score (LPS) Statement
Score
I have lots of sputum in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
I feel like something is stuck in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
I frequently clear my throat because I feel I have sputum in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
My neck is numb and I feel discomfort (or pain). 0———1———2———3———4———5———6———7———8———9———10
_________
Total score Instructions: Please select the number on the scale indicating the level of the symptom according to how frequently you have the same experience: 0 (no symptom), 5 (moderate), 10 (always)
Fig. 1 Summary of patient flow throughout study. LMA laryngeal mask airway, ETI endotracheal intubation, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngo-pharyngeal symptom score
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5105, version 3.1.7; KayPENTAX). Parameters considered in the analysis were the fundamental frequency (F0), perturbations of fundamental frequency (jitter), amplitude (shimmer), glottal noise [i.e., the noise-to-harmonic ratio (NHR)], and speaking fundamental frequency (SFF). In previous investigations, a postoperative lower-pitched voice was not clearly defined. Some authors reported that the average early postoperative reduction in SFF was 12 Hz in females [6]. Therefore, we defined patients with a lowerpitched voice as those in whom the postoperative SFF was reduced by more than 12 Hz in females. However, there are differences in the average F0 between males and females (100–150 Hz in males, 200–250 Hz in females), so the frequency difference within one semitone in males was different from that in females. Therefore, we defined a lowerpitched voice in males as a reduction in the postoperative SFF by more than 6 Hz. Voice handicap index (VHI) The VHI consists of 30 questions divided by content into three categories: functional, emotional, and physical. This questionnaire was completed by each patient using a fivepoint rating scale to indicate his or her response. The VHI is an ordinal scale that is scored from 0 (never) to 4 (always), with a minimum score of 0 and a maximum score of 120. A higher score indicates a more severe perception of disability due to the voice problem [16]. M.D. Anderson dysphagia index (MDADI) The global assessment consisted of a single question regarding how the individual’s swallowing difficulty
affected their overall daily routine. Five possible responses to the items on the M.D. Anderson dysphagia index (MDADI) were printed for each item (strongly agree, agree, no opinion, disagree, and strongly disagree) and scored on a scale of 1–5. All other questions regarding each aspect (emotional, functional, and physical) of dysphagia were summed, and a mean score was then calculated. This mean score was multiplied by 20 to obtain a score with a range of 0 (extremely low functioning) to 100 (high functioning). Thus, a higher MDADI score represented better day-to-day functioning and better quality of life [17]. Laryngopharyngeal symptom score We previously devised a thyroidectomy-related voice questionnaire consisting of 20 questions and evaluated the utility of the instrument in terms of screening prior to thyroidectomy [18]. We excluded voice- and swallowingrelated questions, and finally selected four questions regarding laryngopharyngeal symptoms for the present study. A visual analog scale was used for each item (Table 1). Assessment of outcomes The primary outcome of this study was the difference of the postoperative acoustic parameters between two groups. Secondary outcomes were the differences of VHI, MDADI, and laryngopharyngeal symptom score (LPS) between two groups after surgery. Acoustic analyses were performed preoperatively and at 48 h and 2 weeks postoperatively. The VHI, MDADI, and LPS were determined preoperatively and at 24 h, 48 h, 1 week, and 2 weeks postthyroidectomy.
Table 2 Baseline characteristics of the two groups Variables
LMA group
ETI group
Number of patients
30
33
P value
Age (years)
47.43 ± 9.42
45.97 ± 11.56
0.637
Sex (male/female) F0 (male/female)
10/21 112.9 ± 10.2/204.5 ± 20.5
9/23 111.3 ± 9.5/203.1 ± 24.0
0.552 0.447/0.954
SFF (male/female)
107.5 ± 8.48/199.8 ± 20.6
107.3 ± 9.16/197.1 ± 22.3
0.968/0.873
Jitter
1.23 ± 1.20
1.29 ± 0.75
0.162
Shimmer
3.90 ± 1.86
4.03 ± 1.11
0.319
NHR
0.14 ± 0.07
0.14 ± 0.03
0.489
VHI
6.83 ± 14.73
6.55 ± 12.52
0.511
MDADI
93.60 ± 12.07
95.94 ± 8.24
0.584
LPS
4.93 ± 7.46
3.00 ± 5.41
0.823
Values are presented as mean scores ± SD LMA laryngeal mask airway, ETI endotracheal intubation, F0 fundamental frequency, SFF speech fundamental frequency, NHR noise-toharmonic ratio, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngopharyngeal symptom score P value = v2 test or Mann–Whitney U-test
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clinically significant. For comparison of these two proportions in independent samples, a sample size of 35 patients per group was calculated (two-tailed z test with a = 0.05, power = 80 %, and accounting for a 10 % dropout rate). The significance of differences between groups was determined using Wilcoxon’s signed-rank test or Mann– Whitney U-test. The v2 test or Fisher’s exact test was used to examine differences in categorical variables. In all analyses, P \ 0.05 was taken to indicate statistical significance.
Results Baseline characteristics A total of 63 patients completed the study between July 2013 and February 2014. Two patients in the LMA group were excluded during the study because of follow-up loss, representing a dropout rate of 8.5 %. The LMA and ETI groups consisted of 31 and 33 patients, respectively (Fig. 1). There was no patients had postoperative vocal cord palsy. Baseline characteristics were comparable between the two study groups (Table 2). Acoustic analysis
Fig. 2 Comparison of acoustic parameters. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the two groups (P \ 0.05)
Statistical analysis All statistical analyses were performed using the SPSS software (version 18.0 for Windows; SPSS, Chicago, IL). Sample size was calculated based on the results of our previous study, in which 65 % of patients had moderate-tosevere voice and swallowing-related symptoms after thyroidectomy [19]. Decreases of 30 % in voice and swallowing-related subscores by at least one point in the LMA group compared to the ETI group were considered
Figure 2 shows the scores of acoustic parameters at each time point (preoperative, 48 h, and 2 weeks after thyroidectomy). Prior to surgery, jitter, shimmer, and NHR were not significantly different between the two groups. At 48 h postoperatively, jitter, shimmer and NHR scores were significantly poorer in the ETI group than the LMA group. All parameters in both groups returned to the preoperative values by 2 weeks after surgery. We compared the pre- and postoperative F0 and SFF from the acoustic analysis according to sex. In total, F0 and SFF were significantly reduced at 48 h after surgery. At 2 weeks postoperatively, the pitch was recovered to the preoperative state in male patients. In female patients, pitch did not recover to the preoperative state within 2 weeks, although there was no statistically significant difference between the LMA and ETI groups. In male patients, F0 at 48 h after surgery was significantly different between the two groups (Fig. 3). The incidence of lower-pitched voice after surgery was significantly lower in the LMA group than the ETI group. At 48 h postoperatively, the incidences of lowered F0 were 20 and 77.8 % in the LMA and ETI groups, respectively, while those of lowered SFF were 20 and 66.6 %, respectively. In female patients, the incidences
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World J Surg Fig. 3 Comparison of F0 and SFF between the groups. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the groups by Mann–Whitney U test (P \ 0.05)
Table 3 Postoperative lower-pitched voice at 2 days postoperatively in the two groups LMA group
ETI group
P-value
of lowered F0 were 4.7 and 34.7 % in the LMA and ETI groups, respectively, while those of lowered SFF were 14.2 and 34.7 %, respectively (Table 3).
Male F0
2/10 (20 %)
7/9 (77.8 %)
0.019*
SFF
2/10 (20 %)
6/9 (66.6 %)
0.055
Female F0
1/21 (4.7 %)
8/23 (34.7 %)
0.027*
SFF
3/21 (14.2 %)
8/23 (34.7 %)
0.288
LMA laryngeal mask airway, ETI endotracheal intubation, F0 fundamental frequency, SFF speech fundamental frequency * Significant difference between the groups by Fisher’s exact test (P \ 0.05)
Subjective questionnaires (VHI, MDADI, LPS) The VHI, MDADI, and LPS of both groups at 24 h postoperatively were significantly poorer compared to the preoperative state and improved over time. The VHI of the LMA group was significantly lower compared to the ETI group until 1 week postoperatively. The VHI of the LMA group returned to the preoperative value within 1 week. However, the VHI score in the ETI group remained higher
Table 4 Comparison of VHI, MDADI, and LPS between the two groups Preoperative
24 h
48 h
1 week
2 weeks
VHI LMA
6.83 ± 14.73
29.03 ± 26.12*
18.16 ± 28.12*
8.83 ± 14.50
8.80 ± 13.45
ETI MDADI
6.55 ± 12.52
38.73 ± 30.80*
31.20 ± 26.80*
18.05 ± 20.71*
9.29 ± 10.78
LMA
93.6 ± 12.07
56.30 ± 14.40*
65.26 ± 10.56*
87.76 ± 11.30
92.46 ± 8.76
ETI
95.9 ± 8.24
46.88 ± 10.50*
60.61 ± 13.93*
85.26 ± 7.41*
92.14 ± 8.34
LPS LMA
4.93 ± 7.46
15.43 ± 9.24*
9.56 ± 9.51*
6.83 ± 7.62
5.40 ± 6.18
ETI
3.00 ± 5.41
19.76 ± 7.69*
14.70 ± 7.50*
9.38 ± 6.20*
5.88 ± 5.13*
Values are presented as mean scores ± SD LMA laryngeal mask airway, ETI endotracheal intubation, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngopharyngeal symptom score * Significant difference compared with the preoperative value by Wilcoxon’s signed-rank test (P \ 0.05)
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group remained elevated compared to the preoperative level 2 weeks postoperatively.
Discussion
Fig. 4 Comparison of the questionnaires (VHI, MDADI, LPS) between the groups. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the groups by Mann– Whitney U test (P \ 0.05)
than the preoperative value 1 week after surgery. The MDADI of the LMA group was significantly better than that of the ETI group 24 h after surgery, and improved to the preoperative value within 1 week. The MDADI of the ETI group was still lower than the preoperative value at 1 week postoperatively, but improved within 2 weeks (Table 4; Fig. 4). LPS of the LMA group had a better score than that of the ETI group until 1 week after surgery. The LPS of the LMA group improved within 1 week, but that of the ETI
The main focus of the present randomized controlled study was whether patients undergoing general anesthesia during thyroid surgery with an LMA have better postoperative vocal and swallowing function results than those with ETI. Our hypothesis was that the vocal and swallowing function would be better with use of an LMA because its supraglottic placement could result in less irritation of the vocal cords and trachea. Furthermore, thyroid surgery is usually performed near the cervical trachea, so the laryngeal irritation would be more severe than in other types of surgery. The results of the present study indicated that patients receiving general anesthesia during thyroidectomy with the LMA during surgery had better results in acoustic parameters and subjective voice and swallowing function compared to those treated with ETI. The LMA is an alternative device for anesthetic airway management. The LMA consists of an airway tube that connects to an elliptical mask with a cuff. When inflated, the mask conforms to the anatomy with the bowl of the mask facing the laryngeal inlet, so the tube can be inserted without direct vision of the larynx. After correct insertion, the tip of the mask sits in the throat against the muscular valve that is located at the upper portion of the esophagus to prevent aspiration. Therefore, the LMA was initially used in cases with difficult ETI during emergency or intraoral surgery, such as tonsillectomy, to prevent aspiration of surgical debris during the operation [13]. Recently, because of its placement superior to the larynx, many authors have hypothesized the LMA would result in less laryngeal irritation than the ETI, and evaluated differences in postoperative symptoms, such as throat pain, hoarseness, and cough, after surgery with the LMA and with the ETI. Several studies indicated that the LMA reduced postoperative symptoms after general anesthesia compared with the ETI. However, there have been no previous reports regarding acoustic analysis and evaluation of swallowing function between the two techniques in thyroidectomy. In the results, the subjective and objective symptoms of the patients improved to the preoperative state in both the LMA and ETI groups 2 weeks after thyroidectomy. A long-term result of over 1 month in some patients also showed no difference between the two groups. However, the duration of symptoms in the LMA group was shorter than that in the ETI group when compared within 2 weeks. As shown in Fig. 4, the VHI and LPS in the ETI group remained abnormal 1 week after surgery, while those in the
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LMA group improved to the preoperative level within 1 week. Therefore, it is important to inform patients of these effects during preoperative counseling. The lower-pitched voice of female patients was not statistically different between the LMA and ETI groups when compared 2 weeks after surgery. However, the F0 and SFF of the ETI group were lower than those of the LMA group 2 weeks after surgery in female patients. This may relate to differences in ossification of the thyroid cartilage in males and females; the female larynx is relatively soft because of incomplete ossification, and so is more susceptible to mechanical effects before and after surgery [19]. In this sense, difficulty in producing a highpitched voice after surgery seems to be a more common complication of thyroidectomy in females than male patients. Consequently, general anesthesia with the LMA during thyroidectomy could result in better postoperative voice outcome compared to the ETI. Especially, for female patients or patients who use their voice professionally, such as singers, teachers, or telemarketers, the LMA helps to protect voice quality after thyroidectomy.
Conclusions Voice, swallowing function, and laryngopharyngeal symptoms were improved to the preoperative state in both the LMA and ETI groups, 2 weeks after thyroidectomy. But, the duration of symptoms in the LMA group was shorter than that in the ETI group. Therefore, use of the LMA in general anesthesia during thyroid surgery has advantages over the ETI in terms of patients’ voice, swallowing, and relief of laryngopharyngeal symptoms. Conflict of interest
None.
References 1. Bhattacharyya N, Fried MP (2002) Assessment of the morbidity and complications of total thyroidectomy. Arch Otolaryngol Head Neck Surg 128:389–392 2. McIvor NP, Flint DJ, Gillibrand J et al (2000) Thyroid surgery and voice-related outcomes. Aust NZ J Surg 70:179–183
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3. Aluffi P, Policarpo M, Cherovac C et al (2001) Post-thyroidectomy superior laryngeal nerve injury. Eur Arch Otorhinolaryngol 258:451–454 4. Keilmann A, Hulse M (1992) Dysphonia following strumectomy with normal respiratory movement of the vocal cords. Folia Phoniatr 44:261–268 5. Page C, Zaatar R, Biet A et al (2007) Subjective voice assessment after thyroid surgery: a prospective study of 395 patients. Indian J Med Sci 61:448–454 6. Debruyne F, Ostyn F, Delaere P et al (1997) Acoustic analysis of the speaking voice after thyroidectomy. J Voice 11:479–482 7. Jones MW, Catling S, Evans E et al (1992) Hoarseness after tracheal intubation. Anaesthesia 47:213–216 8. McHardy FE, Chung F (1999) Postoperative sore throat: cause, prevention and treatment. Anaesthesia 54:444–453 9. Mencke T, Echternach M, Kleinschmidt S et al (2003) Laryngeal morbidity and quality of tracheal intubation: a randomized controlled trial. Anesthesiology 98:1049–1056 10. Biro P, Seifert B, Pasch T (2005) Complaints of sore throat after tracheal intubation: a prospective evaluation. Eur J Anaesthesiol 22:307–311 11. Combes X, Schauvliege F, Peyrouset O et al (2001) Intracuff pressure and tracheal morbidity: influence of filling with saline during nitrous oxide anesthesia. Anesthesiology 95:1120–1124 12. Radu AD, Miled F, Marret E et al (2008) Pharyngo-laryngeal discomfort after breast surgery: comparison between orotracheal intubation and laryngeal mask. Breast 17:407–411 13. Bennett J, Petito A, Zandsberg S (1996) Use of the laryngeal mask airway in oral and maxillofacial surgery. J Oral Maxillofac Surg 54:1346–1351 14. Shah EF, Allen JG, Greatorex RA (2001) Use of the laryngeal mask airway in thyroid and parathyroid surgery as an aid to the identification and preservation of the recurrent laryngeal nerves. Ann R Coll Surg Engl 83:315–318 15. Ryu JH, Yom CK, Park DJ et al (2014) Prospective randomized controlled trial on the use of flexible reinforced laryngeal mask airway (LMA) during total thyroidectomy: effects on postoperative laryngopharyngeal symptoms. World J Surg 38:378–384. doi:10.1007/s00268-013-2269-1 16. Park JO, Shim MR, Hwang YS et al (2012) Combination of voice therapy and antireflux therapy rapidly recovers voice-related symptoms in laryngopharyngeal reflux patients. Otolaryngol Head Neck Surg 146:92–97 17. Chen AY, Frankowski R, Bishop-Leone J et al (2001) The development and validation of a dysphagia-specific quality-oflife questionnaire for patients with head and neck cancer: the M. D. Anderson dysphagia inventory. Arch Otolaryngol Head Neck Surg 127:870–876 18. Nam IC, Bae JS, Shim MR et al (2012) The importance of preoperative laryngeal examination before thyroidectomy and the usefulness of a voice questionnaire in screening. World J Surg 36:303–309. doi:10.1007/s00268-011-1347-5 19. Mupparapu M, Vuppalapati A (2005) Ossification of laryngeal cartilages on lateral cephalometric radiographs. Angle Orthod 75:196–201
ORIGINAL SCIENTIFIC REPORT
A Prospective Randomized Controlled Trial of the Laryngeal Mask Airway Versus the Endotracheal Intubation in the Thyroid Surgery: Evaluation of Postoperative Voice, and Laryngopharyngeal Symptom Byung-Joon Chun • Ja-Sung Bae • So-Hui Lee Jin Joo • Eun-Sung Kim • Dong-Il Sun
•
Ó Socie´te´ Internationale de Chirurgie 2015
Abstract Background The present study was performed to determine whether thyroidectomy patients undergoing general anesthesia provided with a laryngeal mask airway (LMA) have a lower risk of voice-related complications and laryngopharyngeal symptoms than those undergoing endotracheal intubation (ETI). Materials and methods In a prospective, double-blinded, randomized clinical trial, we studied 64 patients undergoing elective thyroid lobectomy between July 2013 and February 2014. Acoustic analyses were performed preoperatively and at 48 h and 2 weeks postoperatively. The voice handicap index (VHI), M.D. Anderson dysphagia index (MDADI), and laryngopharyngeal symptom score (LPS) were determined preoperatively and at 24 h, 48 h, 1 week, and 2 weeks post-thyroidectomy. Results In acoustic analysis, jitter, shimmer and noise-to-harmonic ratio showed significantly better results in the LMA group than the ETI group 48 h after surgery, but there was no difference at 2 weeks. The incidence of postoperative lower-pitched voice in the LMA group was also significantly lower than that in the ETI group. In the LMA group, the VHI, MDADI, and LPS were better compared to those in the ETI group at 24 h postoperatively, and improved to the preoperative state within 1 week. However, those in the ETI group remained poorer than the preoperative values 1 week after surgery. Conclusions Use of the LMA in general anesthesia for thyroid surgery has advantages over the ETI in decreasing patients’ subjective and objective voice symptoms, reducing the duration of symptoms, and relieving the laryngopharyngeal symptoms.
B.-J. Chun D.-I. Sun (&) Department of Otorhinolaryngology-Head and Neck Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea e-mail: [email protected] J.-S. Bae S.-H. Lee Department of Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea J. Joo E.-S. Kim Department of Anesthesiology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
Introduction Thyroid disease has a high prevalence in the general population, particularly in females [1]. Thyroidectomy is a frequently used surgical procedure to treat thyroid disease, and vocal dysfunction is the most likely complication of this procedure. There have been many reports that patients undergoing thyroidectomy developed voice dysfunction postoperatively [1–4]. One report indicated that the voice change after thyroidectomy without any evident laryngeal injury shows typical characteristics, such as voice fatigue and difficulty making higher pitched sounds, hoarseness, low voice, and weak voice [5]. There are several possible
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causes of post-thyroidectomy voice dysfunction without laryngeal nerve injury. First, surgical manipulation and disturbed vascularization may cause nerve dysfunction. Second, the strap muscles that play an important regulatory function in phonation may be divided and damaged, which can lead to changes in tension and motility of the internal and external laryngeal muscles. Removal of the thyroid gland modifies the vascular supply and venous drainage of the larynx. Together with endotracheal intubation (ETI), this may cause alterations in the mucosa as slight congestion, which may in part explain the lower-pitched voice [6]. The incidence of side effects (laryngeal pain, hoarseness, dysphonia) related to ETI in the early postoperative period ranges from 15 to 50 % [7–10]. Several reports have identified risk factors for laryngeal morbidity following tracheal intubation including endotracheal tube size, cuff design, and cuff pressure [8–11]. The laryngeal mask airway (LMA) is an alternative to ETI for controlling the upper airway and permitting mechanical ventilation, and use of the LMA may decrease the risk of laryngeal trauma. In previous studies, the incidences of postoperative sore throat and hoarseness were significantly higher in patients treated using the ETI compared to those using LMA [12, 13]. Several studies have indicated the usefulness of LMA in thyroid surgery [14, 15]. However, there have been few comparisons of the objective acoustic parameters of voice dysfunction between anesthesia with LMA and ETI in thyroid surgery. Therefore, the present study was performed to compare the postoperative acoustic parameters, subjective vocal and swallowing function, and laryngopharyngeal symptoms between ETI and LMA during thyroidectomy.
Materials and methods Study design A prospective, double-blind, randomized clinical trial was performed to evaluate the usefulness of the LMA compared to ETI by analyzing changes in clinical symptoms and acoustic parameters before and after surgery. The Institutional Review Board of the Office of Human Research Protection at Catholic Medical Center, Seoul, Korea approved the study. Patients The study population consisted of 64 patients treated between July 2013 and February 2014. Written informed consent was obtained from each patient during the preoperative visit. We selected single papillary thyroid
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carcinoma (\1 cm) patients to minimize surgical factors for patients’ voice and swallowing symptoms. All patients underwent thyroid lobectomy without central node dissection by one surgeon in our Department of Surgery and were referred to our Department of Otolaryngology/Headand-Neck Surgery for pre- and postoperative voice evaluation. We used fiberoptic laryngoscopy (Machida Instruments, Tokyo, Japan) and videolaryngostroboscopy (model 9200C; KayPENTAX, Lincoln Park, NJ, USA) to examine the larynx at the pre- and postoperative period. Exclusion criteria were as follows: previous neck surgery or revision thyroidectomy; preoperative laryngeal disorder, such as vocal nodules, vocal polyps, or vocal cord paralysis; dental or upper airway infection; or expected duration of surgery [2 h. Patients with criteria of difficult intubation (mouth opening \35 mm, thyromental distance \60 mm, Mallampati grade [3) were also excluded from the study. Patients were randomized into one of two groups using a coded, opaque, sealed envelope technique. Allocation was performed in the operating room just before induction of anesthesia. The general anesthesia was performed by one skilled anesthesiology physician. No premedication was administered to the patients. Electrocardiogram, noninvasive blood pressure, heart rate, and pulse oximetry were measured continuously at 5-min intervals, starting at the time of arrival in the operating room. General anesthesia was induced with 2 mg/kg propofol and 0.6 mg/kg rocuronium. When patients were fully sedated and relaxed, endotracheal tube (MallinckrodtÒ 6.5–7.5; Covidien, Dublin, Ireland) was in the ETI group, and LMA FlexibleTM (size 3–5 according to the patient’s weight; Teleflex, Dublin, Ireland) was inserted in the LMA group. Anesthesia was maintained with 1.5–2 vol.% sevoflurane, medical air in oxygen [fraction of inspired O2 (FiO2) = 0.5], and continuously infused IV remifentanil 0.05–0.1 lg/kg/min, keeping end-tidal CO2 between 35 and 40 mmHg throughout the surgery. Ringer’s lactate solution was administered at 6–8 ml/kg/h during surgery. When ventilation difficulty occurred during tracheal manipulation, the anaesthetist immediately reported the surgeon, and the trachea was handled with care. At the end of the surgical procedure, sevoflurane and remifentanil administration were discontinued. IV 0.2 mg/kg pyridostigmine and 0.008 mg/kg glycopyrrolate were administered for reversal of muscle relaxation. The trachea was extubated in the ETI group and the LMA FlexibleTM was removed in the LMA group when spontaneous respiration of the patient was adequate. Acoustic analysis All patients were instructed to pronounce the vowel /a/ at a comfortable volume and constant pitch. Each vowel
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pronunciation was recorded with a constant mouth-tomicrophone distance of 5 cm using the Computerized Speech Lab (model 4150; KayPENTAX, Montvale, NJ). All digital recordings were made in a soundproofed room. Each
patient sustained an /a/ for at least 3 s at a comfortable pitch level. The task was repeated at least four times, and the fourth trial was often the recorded sample. Each analysis was performed using a multidimensional voice program (model
Table 1 Laryngopharyngeal symptom score (LPS) Statement
Score
I have lots of sputum in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
I feel like something is stuck in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
I frequently clear my throat because I feel I have sputum in my throat. 0———1———2———3———4———5———6———7———8———9———10
_________
My neck is numb and I feel discomfort (or pain). 0———1———2———3———4———5———6———7———8———9———10
_________
Total score Instructions: Please select the number on the scale indicating the level of the symptom according to how frequently you have the same experience: 0 (no symptom), 5 (moderate), 10 (always)
Fig. 1 Summary of patient flow throughout study. LMA laryngeal mask airway, ETI endotracheal intubation, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngo-pharyngeal symptom score
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5105, version 3.1.7; KayPENTAX). Parameters considered in the analysis were the fundamental frequency (F0), perturbations of fundamental frequency (jitter), amplitude (shimmer), glottal noise [i.e., the noise-to-harmonic ratio (NHR)], and speaking fundamental frequency (SFF). In previous investigations, a postoperative lower-pitched voice was not clearly defined. Some authors reported that the average early postoperative reduction in SFF was 12 Hz in females [6]. Therefore, we defined patients with a lowerpitched voice as those in whom the postoperative SFF was reduced by more than 12 Hz in females. However, there are differences in the average F0 between males and females (100–150 Hz in males, 200–250 Hz in females), so the frequency difference within one semitone in males was different from that in females. Therefore, we defined a lowerpitched voice in males as a reduction in the postoperative SFF by more than 6 Hz. Voice handicap index (VHI) The VHI consists of 30 questions divided by content into three categories: functional, emotional, and physical. This questionnaire was completed by each patient using a fivepoint rating scale to indicate his or her response. The VHI is an ordinal scale that is scored from 0 (never) to 4 (always), with a minimum score of 0 and a maximum score of 120. A higher score indicates a more severe perception of disability due to the voice problem [16]. M.D. Anderson dysphagia index (MDADI) The global assessment consisted of a single question regarding how the individual’s swallowing difficulty
affected their overall daily routine. Five possible responses to the items on the M.D. Anderson dysphagia index (MDADI) were printed for each item (strongly agree, agree, no opinion, disagree, and strongly disagree) and scored on a scale of 1–5. All other questions regarding each aspect (emotional, functional, and physical) of dysphagia were summed, and a mean score was then calculated. This mean score was multiplied by 20 to obtain a score with a range of 0 (extremely low functioning) to 100 (high functioning). Thus, a higher MDADI score represented better day-to-day functioning and better quality of life [17]. Laryngopharyngeal symptom score We previously devised a thyroidectomy-related voice questionnaire consisting of 20 questions and evaluated the utility of the instrument in terms of screening prior to thyroidectomy [18]. We excluded voice- and swallowingrelated questions, and finally selected four questions regarding laryngopharyngeal symptoms for the present study. A visual analog scale was used for each item (Table 1). Assessment of outcomes The primary outcome of this study was the difference of the postoperative acoustic parameters between two groups. Secondary outcomes were the differences of VHI, MDADI, and laryngopharyngeal symptom score (LPS) between two groups after surgery. Acoustic analyses were performed preoperatively and at 48 h and 2 weeks postoperatively. The VHI, MDADI, and LPS were determined preoperatively and at 24 h, 48 h, 1 week, and 2 weeks postthyroidectomy.
Table 2 Baseline characteristics of the two groups Variables
LMA group
ETI group
Number of patients
30
33
P value
Age (years)
47.43 ± 9.42
45.97 ± 11.56
0.637
Sex (male/female) F0 (male/female)
10/21 112.9 ± 10.2/204.5 ± 20.5
9/23 111.3 ± 9.5/203.1 ± 24.0
0.552 0.447/0.954
SFF (male/female)
107.5 ± 8.48/199.8 ± 20.6
107.3 ± 9.16/197.1 ± 22.3
0.968/0.873
Jitter
1.23 ± 1.20
1.29 ± 0.75
0.162
Shimmer
3.90 ± 1.86
4.03 ± 1.11
0.319
NHR
0.14 ± 0.07
0.14 ± 0.03
0.489
VHI
6.83 ± 14.73
6.55 ± 12.52
0.511
MDADI
93.60 ± 12.07
95.94 ± 8.24
0.584
LPS
4.93 ± 7.46
3.00 ± 5.41
0.823
Values are presented as mean scores ± SD LMA laryngeal mask airway, ETI endotracheal intubation, F0 fundamental frequency, SFF speech fundamental frequency, NHR noise-toharmonic ratio, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngopharyngeal symptom score P value = v2 test or Mann–Whitney U-test
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clinically significant. For comparison of these two proportions in independent samples, a sample size of 35 patients per group was calculated (two-tailed z test with a = 0.05, power = 80 %, and accounting for a 10 % dropout rate). The significance of differences between groups was determined using Wilcoxon’s signed-rank test or Mann– Whitney U-test. The v2 test or Fisher’s exact test was used to examine differences in categorical variables. In all analyses, P \ 0.05 was taken to indicate statistical significance.
Results Baseline characteristics A total of 63 patients completed the study between July 2013 and February 2014. Two patients in the LMA group were excluded during the study because of follow-up loss, representing a dropout rate of 8.5 %. The LMA and ETI groups consisted of 31 and 33 patients, respectively (Fig. 1). There was no patients had postoperative vocal cord palsy. Baseline characteristics were comparable between the two study groups (Table 2). Acoustic analysis
Fig. 2 Comparison of acoustic parameters. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the two groups (P \ 0.05)
Statistical analysis All statistical analyses were performed using the SPSS software (version 18.0 for Windows; SPSS, Chicago, IL). Sample size was calculated based on the results of our previous study, in which 65 % of patients had moderate-tosevere voice and swallowing-related symptoms after thyroidectomy [19]. Decreases of 30 % in voice and swallowing-related subscores by at least one point in the LMA group compared to the ETI group were considered
Figure 2 shows the scores of acoustic parameters at each time point (preoperative, 48 h, and 2 weeks after thyroidectomy). Prior to surgery, jitter, shimmer, and NHR were not significantly different between the two groups. At 48 h postoperatively, jitter, shimmer and NHR scores were significantly poorer in the ETI group than the LMA group. All parameters in both groups returned to the preoperative values by 2 weeks after surgery. We compared the pre- and postoperative F0 and SFF from the acoustic analysis according to sex. In total, F0 and SFF were significantly reduced at 48 h after surgery. At 2 weeks postoperatively, the pitch was recovered to the preoperative state in male patients. In female patients, pitch did not recover to the preoperative state within 2 weeks, although there was no statistically significant difference between the LMA and ETI groups. In male patients, F0 at 48 h after surgery was significantly different between the two groups (Fig. 3). The incidence of lower-pitched voice after surgery was significantly lower in the LMA group than the ETI group. At 48 h postoperatively, the incidences of lowered F0 were 20 and 77.8 % in the LMA and ETI groups, respectively, while those of lowered SFF were 20 and 66.6 %, respectively. In female patients, the incidences
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World J Surg Fig. 3 Comparison of F0 and SFF between the groups. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the groups by Mann–Whitney U test (P \ 0.05)
Table 3 Postoperative lower-pitched voice at 2 days postoperatively in the two groups LMA group
ETI group
P-value
of lowered F0 were 4.7 and 34.7 % in the LMA and ETI groups, respectively, while those of lowered SFF were 14.2 and 34.7 %, respectively (Table 3).
Male F0
2/10 (20 %)
7/9 (77.8 %)
0.019*
SFF
2/10 (20 %)
6/9 (66.6 %)
0.055
Female F0
1/21 (4.7 %)
8/23 (34.7 %)
0.027*
SFF
3/21 (14.2 %)
8/23 (34.7 %)
0.288
LMA laryngeal mask airway, ETI endotracheal intubation, F0 fundamental frequency, SFF speech fundamental frequency * Significant difference between the groups by Fisher’s exact test (P \ 0.05)
Subjective questionnaires (VHI, MDADI, LPS) The VHI, MDADI, and LPS of both groups at 24 h postoperatively were significantly poorer compared to the preoperative state and improved over time. The VHI of the LMA group was significantly lower compared to the ETI group until 1 week postoperatively. The VHI of the LMA group returned to the preoperative value within 1 week. However, the VHI score in the ETI group remained higher
Table 4 Comparison of VHI, MDADI, and LPS between the two groups Preoperative
24 h
48 h
1 week
2 weeks
VHI LMA
6.83 ± 14.73
29.03 ± 26.12*
18.16 ± 28.12*
8.83 ± 14.50
8.80 ± 13.45
ETI MDADI
6.55 ± 12.52
38.73 ± 30.80*
31.20 ± 26.80*
18.05 ± 20.71*
9.29 ± 10.78
LMA
93.6 ± 12.07
56.30 ± 14.40*
65.26 ± 10.56*
87.76 ± 11.30
92.46 ± 8.76
ETI
95.9 ± 8.24
46.88 ± 10.50*
60.61 ± 13.93*
85.26 ± 7.41*
92.14 ± 8.34
LPS LMA
4.93 ± 7.46
15.43 ± 9.24*
9.56 ± 9.51*
6.83 ± 7.62
5.40 ± 6.18
ETI
3.00 ± 5.41
19.76 ± 7.69*
14.70 ± 7.50*
9.38 ± 6.20*
5.88 ± 5.13*
Values are presented as mean scores ± SD LMA laryngeal mask airway, ETI endotracheal intubation, VHI voice handicap index, MDADI M.D. Anderson dysphagia index, LPS laryngopharyngeal symptom score * Significant difference compared with the preoperative value by Wilcoxon’s signed-rank test (P \ 0.05)
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group remained elevated compared to the preoperative level 2 weeks postoperatively.
Discussion
Fig. 4 Comparison of the questionnaires (VHI, MDADI, LPS) between the groups. LMA laryngeal mask airway, ETI endotracheal intubation. *Significant difference between the groups by Mann– Whitney U test (P \ 0.05)
than the preoperative value 1 week after surgery. The MDADI of the LMA group was significantly better than that of the ETI group 24 h after surgery, and improved to the preoperative value within 1 week. The MDADI of the ETI group was still lower than the preoperative value at 1 week postoperatively, but improved within 2 weeks (Table 4; Fig. 4). LPS of the LMA group had a better score than that of the ETI group until 1 week after surgery. The LPS of the LMA group improved within 1 week, but that of the ETI
The main focus of the present randomized controlled study was whether patients undergoing general anesthesia during thyroid surgery with an LMA have better postoperative vocal and swallowing function results than those with ETI. Our hypothesis was that the vocal and swallowing function would be better with use of an LMA because its supraglottic placement could result in less irritation of the vocal cords and trachea. Furthermore, thyroid surgery is usually performed near the cervical trachea, so the laryngeal irritation would be more severe than in other types of surgery. The results of the present study indicated that patients receiving general anesthesia during thyroidectomy with the LMA during surgery had better results in acoustic parameters and subjective voice and swallowing function compared to those treated with ETI. The LMA is an alternative device for anesthetic airway management. The LMA consists of an airway tube that connects to an elliptical mask with a cuff. When inflated, the mask conforms to the anatomy with the bowl of the mask facing the laryngeal inlet, so the tube can be inserted without direct vision of the larynx. After correct insertion, the tip of the mask sits in the throat against the muscular valve that is located at the upper portion of the esophagus to prevent aspiration. Therefore, the LMA was initially used in cases with difficult ETI during emergency or intraoral surgery, such as tonsillectomy, to prevent aspiration of surgical debris during the operation [13]. Recently, because of its placement superior to the larynx, many authors have hypothesized the LMA would result in less laryngeal irritation than the ETI, and evaluated differences in postoperative symptoms, such as throat pain, hoarseness, and cough, after surgery with the LMA and with the ETI. Several studies indicated that the LMA reduced postoperative symptoms after general anesthesia compared with the ETI. However, there have been no previous reports regarding acoustic analysis and evaluation of swallowing function between the two techniques in thyroidectomy. In the results, the subjective and objective symptoms of the patients improved to the preoperative state in both the LMA and ETI groups 2 weeks after thyroidectomy. A long-term result of over 1 month in some patients also showed no difference between the two groups. However, the duration of symptoms in the LMA group was shorter than that in the ETI group when compared within 2 weeks. As shown in Fig. 4, the VHI and LPS in the ETI group remained abnormal 1 week after surgery, while those in the
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LMA group improved to the preoperative level within 1 week. Therefore, it is important to inform patients of these effects during preoperative counseling. The lower-pitched voice of female patients was not statistically different between the LMA and ETI groups when compared 2 weeks after surgery. However, the F0 and SFF of the ETI group were lower than those of the LMA group 2 weeks after surgery in female patients. This may relate to differences in ossification of the thyroid cartilage in males and females; the female larynx is relatively soft because of incomplete ossification, and so is more susceptible to mechanical effects before and after surgery [19]. In this sense, difficulty in producing a highpitched voice after surgery seems to be a more common complication of thyroidectomy in females than male patients. Consequently, general anesthesia with the LMA during thyroidectomy could result in better postoperative voice outcome compared to the ETI. Especially, for female patients or patients who use their voice professionally, such as singers, teachers, or telemarketers, the LMA helps to protect voice quality after thyroidectomy.
Conclusions Voice, swallowing function, and laryngopharyngeal symptoms were improved to the preoperative state in both the LMA and ETI groups, 2 weeks after thyroidectomy. But, the duration of symptoms in the LMA group was shorter than that in the ETI group. Therefore, use of the LMA in general anesthesia during thyroid surgery has advantages over the ETI in terms of patients’ voice, swallowing, and relief of laryngopharyngeal symptoms. Conflict of interest
None.
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