Tracheal intubation was successful in all patients of both groups. Time of intubation, number of attempts, and Cormack and Lehane grades did not differ significantly between study groups. The rate of excellent intubating conditions was significantly more frequent in the succinylcholine group compared with the rocuronium group: 42 (57%) versus 16 patients (21%), respectively (P < 0.001). Similar results were noted for clinically acceptable (excellent and good) intubating conditions: 66 (89%) versus 45 patients (59%), respectively (P < 0.001). Results concerning the subcomponents are shown in Figure 2.
The overall incidence (succinylcholine and rocuronium groups together) of PH was 51% (76 patients). PH did not differ significantly between groups: 37 patients (50%) versus 39 patients (51%), respectively (P = 0.998) (Table 3). In 8 patients (5.3%) (4 patients of each group) PH lasted longer than 3 days. Follow-up examination revealed that 4 patients (2.7%) suffered from PH >7 days (Table 3). The severity of PH did not differ significantly between study groups.
Stroboscopic examination was performed in all 8 patients suffering from PH >3 days. Among these 8 patients 3 patients (2 succinylcholine versus 1 rocuronium patient; P = 0.981) had VCI. All VCI were unilateral (right/left vocal cords = 2/1) and consisted of 1 hematoma, 1 edema, and 1 granuloma. Follow-up examination revealed that this granuloma (succinylcholine group) persisted for 1 wk (Fig. 3).
The overall incidence (both study groups together) of ST was 33% (50 patients). ST did not differ significantly between groups: 29 patients (39%) versus 21 patients (28%), respectively; P = 0.224 (Table 3). The severity of ST did not differ significantly between study groups.
Overall 11 patients (7.3%) suffered from laryngeal morbidity lasting longer than 3 days (PH, 8 patients; ST, 3 patients; VCI, 3 patients). Among them one patient experienced PH for 11 days (hematoma), one for 9 days (edema), and another for 7 days (granuloma of the vocal folds) (Fig. 3).
The relation between the intubating conditions and PH is shown in Figure 4. In the succinylcholine group 21 of 42 patients with an excellent intubating score were hoarse (50%), 10 of 24 patients with good intubating scores were hoarse (42%), and 6 of 8 patients with poor intubating scores were hoarse (75%) (P = not significant). Similar findings were observed in the rocuronium group: 9 of 16 patients with excellent intubating scores were hoarse (56%) compared with 14 of 29 patients with good scores (48%) and 16 of 31 patients with poor intubating scores (52%) (P = not significant).
Between the succinylcholine and rocuronium groups, there was no significant difference concerning the incidence (29 versus 22 patients, respectively; P = 0.250) and severity of POM (Table 4). Bradycardia requiring atropine IV occurred in 6 patients (3 in each group; P = 0.701). No severe bradycardia or arrhythmia was observed.
The present study demonstrated that the rate of excellent and clinically acceptable intubating conditions during a RSI was significantly more frequent in the succinylcholine group compared with the rocuronium group. In addition, succinylcholine was not associated with more frequent incidence and severity of ST and POM. However, the incidence and severity of PH and VCI was similar compared with the rocuronium group.
Many factors contribute to laryngeal intubation trauma (10). Several risk factors for VCI and PH have been identified, including demographic factors such as sex (3) and gastroesophageal reflux (11), technical factors such as endotracheal tube size (9), use of an introducer (3), stomach tube (23), type, and duration of surgery (10,12,13), and the intubating conditions (7). Risk factors known to contribute to PH and VCI were controlled in the present study. The patient population was uniform with respect to the patient characteristics, as well as to the type and duration of surgery (Table 2). Moreover, type of tube, and tube size were standardized (men got a tracheal tube with an inner diameter of 1.0 mm larger than women).
We (7) demonstrated that excellent intubating conditions were less frequently associated with PH and VCI compared with good or poor conditions. In the present study, however, we did not confirm these results. In the group receiving rocuronium 0.6 mg/kg the quality of tracheal intubation was significantly worse than in the group receiving succinylcholine 1.0 mg/kg. In contrast to our first study (7), laryngeal morbidity was not significantly affected by the intubating conditions (Fig. 4). There was no correlation between the incidence and severity of PH or VCI and the intubating conditions or subcomponents. In the first study (7) the saline group received no NMBD; in the present study all patients received a NMBD (rocuronium or succinylcholine). The incidence of poor intubating conditions was 33% (saline group) versus 5% (atracurium group) in the first study, and 11% (succinylcholine) versus 41% (rocuronium) in the present study. The Copenhagen scoring system defines sustained coughing as poor intubating conditions. We suppose that coughing could be different with regard to intensity and therefore lead to different rates of PH, and VCI. However, a baseline incidence of PH and VCI may exist independently of the quality of tracheal intubation during the induction of anesthesia. In the first study the patients underwent surgery of the ear (7) and the head was only slightly moved. In contrast, in the present study the head was fixed after tracheal intubation but the neck was extended during positioning to facilitate laparotomy. This might increase PH and VCI, as known from cardiac surgery (13). In contrast to our first study (7), a stylet was used, a stomach tube placed, and cricoid pressure applied. Turgeon et al. (24) randomized 700 patients to have a standardized cricoid pressure or a sham cricoid pressure. Cricoid pressure applied by trained personnel did not increase the rate of failed intubation. Moreover, the grades of laryngoscopic view and the intubation difficulty scale score were also comparable (24). The results of their study are in contradiction to the common clinical assumption that cricoid pressure impedes visualization of the larynx and with case reports of difficult intubation. In our study only trained anesthesia personnel took part in the study. However, patients with a Cormack and Lehane grade 3 or 4 were excluded after induction of anesthesia. It was standardized that we used a stylet for all patients, but they were limited to the edge of the tracheal tube. An evaluation of the gum elastic bougie (25) showed no increased incidence of hoarseness; the use of an introducer was associated with a longer PH (3). In one case report, a stomach tube was associated with an increased incidence of ST, postcricoid inflammation, and vocal cord immobility (23). These risk factors together might have increased the baseline incidence of PH and therefore the risk factor “poor intubating conditions,” i.e., inadequate muscle relaxation lost its impact on PH in the current study.
There is a large variation in the reported incidence (3%–50%) of PH immediately after short-term tracheal intubation (3–5,7,8). Oczenski et al. (4) reported an incidence of PH of 44% after rocuronium 0.6 mg/kg (the same dosage as in our study). This frequent incidence can be explained by the relatively large size of tracheal tubes that were used (4). Tracheal intubation with atracurium 0.5 mg/kg 3 minutes after induction of anesthesia was associated with an infrequent incidence of PH of 16% (7). Moreover, PH was limited to the PACU and VCI resolved within 72 hours (7). In our current study, however, the overall incidence of PH was as frequent as 51%. Furthermore, at 72 hours almost 9% of the patients were still hoarse, and after 1 week even 3% of the patients suffered from hoarseness (Table 3).
Intubation-related laryngeal injuries were found to be present in up to 12% of patients with the use of NMBD for tracheal intubation (4,7,22,26) and reached 44% in patients with an induction technique without NMBD (7). In the study conducted by Kambic and Radsel (26) in 1000 patients after tracheal extubation using the indirect mirror examination, the incidence of direct lesions was 6.2%. These results were confirmed by Peppard and Dickens (22), who found traumatic lesions in 6.3% of the patients. These studies were done nearly 25 years ago; different tube type or cuff design might lead to different results today. In our study, only patients with a PH lasting longer than 72 hours were examined by laryngostroboscopy. All VCI were unilateral suggesting direct trauma by intubation (22,26). Follow-up examinations revealed that 1 patient in the succinylcholine group had persistent granuloma at the right vocal cord for 1 week (Fig. 3). The infrequent incidence (2%) of VCI in our study could be explained by the design of the study, i.e., patients were examined on the fourth day after surgery, when they were still hoarse. Presumably, most minor injuries of the vocal folds, such as edema, thickening of the vocal folds, or hematoma, might have been resolved in the first 24 or 48 hours after surgery.
ST varies between 14.4%–50% (2,4,5,9). Even in unintubated patients, ST occurred when an ordinary facemask was used (1). These findings have been confirmed by another study (6); others found no effect of succinylcholine on ST (5). In the present study, however, the overall incidence of ST was 33%, being comparable between both study groups (Table 3). The mechanism of postoperative ST is not clear, but it was suggested that succinylcholine could induce muscle pain, i.e., myalgia, in the striated pharyngeal muscles (1,2). POM is characterized by succinylcholine-induced myalgia and other causes (21).
In conclusion, intubating conditions were significantly better in the succinylcholine group compared with the rocuronium group. However, the rate of adverse airway effects was not different between drugs. Succinylcholine should be used if excellent intubating conditions are mandatory.
Appendix: Assessment of Postoperative Hoarseness, Sore Throat, and Postoperative Myalgia
- Postoperative hoarseness (PH)Do you have any hoarseness?
If the answer was no, PH was graded 0 = no hoarseness;
If the answer was yes, PH was graded 1-3 as follows (9):
1 = noticed by patient
2 = obvious to observer or
3 = aphonia.
- Sore throat (ST)Do you have any sore throat?
If the answer was no, ST was graded 0 = no sore throat;
If the answer was yes, ST was graded 1–3 as follows (1):
1 = mild (pain with deglutition)
2 = moderate (pain present constantly and increasing with deglutition)
3 = severe (pain interfering with eating and requiring analgesic medication).
- Postoperative myalgia (POM)1. Do you have any pains and aches or stiffness in your muscles other than the pain where the surgery took place?
2. If the answer was no, myalgia was graded 0 = none (no pain).
3. If the answer was yes, POM was graded 1–3 as follows (20,21):
a. If the pain was confined to one site, myalgia was graded 1 = slight (pain confined to one site but causing no disability).
b. If the pain was affecting more than one site, myalgia was graded 2 = moderate or 3 = severe.
c. Does the muscle pain restrict your normal activity?
i. If the answer was no, myalgia was graded 2 = moderate (pain affecting more than one site but causing no disability).
i. If the answer was yes, myalgia was graded 3 = severe (pain affecting more than one site and resulting in an inability to get out of bed or cough without distress, or turn the head).
1. Capon LM, Bruce DL, Patel KP, Turndorf H. Succinylcholine-induced postoperative sore throat. Anesthesiology 1983;59:202–6.
2. McHardy FE, Chung F. Postoperative sore throat: cause, prevention and treatment. Anaesthesia 1999;54:444–53.
3. Jones MW, Catling S, Evans E, et al Hoarseness after tracheal intubation. Anaesthesia 1992;47:213–6.
4. Oczenski W, Krenn H, Dahaba AA, et al Complications following the use of the combitube, tracheal tube and laryngeal mask airway. Anaesthesia 1999;54:1161–5.
5. Christensen AM, Willemoes-Larsen H, Lundby L, Jakobsen KB. Postoperative throat complaints after tracheal intubation. Br J Anaesth 1994;73:786–7.
6. Higgins PP, Chung F, Mezei G. Postoperative sore throat after ambulatory surgery. Br J Anaesth 2002;88:582–4.
7. Mencke T, Echternach M, Kleinschmidt S, et al Laryngeal morbidity and quality of tracheal intubation. A randomized controlled trial. Anesthesiology 2003;98:1049–56.
8. Kark AE, Kissin MW, Auerbach R, Meikle M. Voice changes after thyroidectomy: role of the external laryngeal nerve. BMJ 1984;289:1412–5.
9. Stout DM, Bishop MJ, Dwersteg JF, Cullen BF. Correlation of endotracheal tube size with sore throat and hoarseness following general anesthesia. Anesthesiology 1987;67:419–21.
10. Benjamin B. Laryngeal trauma from intubation: endoscopic evaluation and classification. In: Cummings CW, Frederickson JM, eds. Otolaryngology & head & neck surgery. St. Louis: Mosby, 2001;2013–35.
11. Smit CF, Mathus-Vliegen LMH, Devriese PP, et al. Diagnosis and consequences of gastropharyngeal reflux. Clin Otolaryngol 2000;25:440–55.
12. Lesser THJ, Lesser PJA. Laryngeal trauma vs length of intubation. J Laryngol Otol 1987;101:1165–7.
13. Inada T, Fujise K, Shingu K. Hoarseness after cardiac surgery. J Cardiovasc Surg 1998;39:455–9.
14. Sparr HJ, Luger TJ, Heidegger T, Putensen-Himmer G. Comparison of intubating conditions after rocuronium and suxamethonium following “rapid-sequence induction” with thiopentone in elective cases. Acta Anaesthesiol Scand 1996;40:425–30.
15. Perry JJ, Lee J, Wells G. Are intubation conditions using rocuronium equivalent to those using succinylcholine? Acad Emerg Med 2002;9:813–23.
16. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105–11.
17. Thwaites AJ, Rice CP, Smith I. Rapid sequence induction: a questionnaire survey of its routine conduct and continued management during a failed intubation. Anaesthesia 1999;54:376–81.
18. Viby-Mogensen J, Englbaek J, Eriksson LI, et al Good clinical research practice (GCRP) in pharmacodynamic studies of neuromuscular blocking agents. Acta Anaesthesiol Scand 1996;40:59–74.
19. Woo P, Colton R, Casper J, Brewer D. Diagnostic value of stroboscopic examination in hoarse patients. J Voice 1991;5:231–8.
20. White DC. Observations on the prevention of muscle pains after suxamethonium. Br J Anaesth 1962;34:332–5.
21. Mencke T, Schreiber JU, Becker C, et al Pretreatment before succinylcholine for outpatient anesthesia? Anesth Analg 2002;94:573–6.
22. Peppard SB, Dickens JH. Laryngeal injury following short-term intubation. Ann Otol Rhinol Laryngol 1983;92:327–30.
23. Friedman M, Toriumi DM. Esophageal stethoscope. Arch Otolaryngol Head Neck Surg 1989;115:95–8.
24. Turgeon AF, Nicole PC, Trepanier CA, et al Cricoid pressure does not increase the rate of failed intubation by direct laryngoscopy in adults. Anesthesiology 2005;102:315–9.
25. Nolan JP, Wilson ME. An evaluation of the gum elastic bougie. Intubation times and incidence of sore throat. Anaesthesia 1992;47:878–81.
© 2006 International Anesthesia Research Society
26. Kambic V, Radsel Z. Intubation lesions of the larynx. Br J Anaesth 1978;50:587–90.