Introduction
Suspension laryngoscopy is a widely used operation for the diagnosis and treatment of laryngeal disorders. Endotracheal intubation and laryngeal surgery conducted via a suspension laryngoscope can trigger abrupt, transient haemodynamic responses, resulting in undesirable side effects such as hypertension and tachycardia.Reference Strong, Vaughan, Mahler, Jaffe and Sullivan1 These reactions develop as a result of the stimulation of afferent fibres of the sympathetic reflex localised in the upper respiratory tract.Reference Sun, Wu, Ng, Chien, Huang and Chie2 The anaesthesiologist's objectives are to minimise the haemodynamic changes related to laryngoscopy and surgery, to protect the trachea, to ensure ventilation and oxygenation, and to promote rapid arousal from anaesthesia and the return of protective airway reflexes.
To achieve all these goals, some adjuvant drugs additional to conventional balanced general anaesthesia have been tried in laryngoscopy performed for endotracheal intubation. In our earlier study, it was indicated that topical or intravenous (IV) lignocaine reduced the incidence of post-operative respiratory complications after microsurgery performed via a rigid suspension laryngoscope.Reference Kocamanoglu, Sener, Ustun and Tur3 Some studies have also demonstrated that topical or IV lignocaine reduces circulatory responses to laryngoscopy conducted for endotracheal intubation during the induction of anaesthesia.Reference Capuzzo, Verri and Alvisi4, Reference Park, Bang, Choi, Hong, Kim and Yeong5 In addition, it has been shown that 10 per cent lignocaine spray is effective for the attenuation of arterial pressure increase induced by suspension laryngoscopy.Reference Lee and Park6 However, no study has compared IV and topical lignocaine or placebo used during surgery conducted via a suspension laryngoscope.
This is the first study to compare the effects of IV and topical lignocaine with placebo on circulatory responses triggered during short-term laryngeal surgery performed using a rigid suspension laryngoscope under conventional balanced general anaesthesia.
Materials and methods
The Ethics Committee of Ondokuz Mayis University approved the study design. Overall, this was a prospective, controlled and double-blinded study. Informed written consent was obtained from all patients; the alternatives of anaesthetic managements and probable complications of the operation were explained to the patients.
The study consisted of the random selection of patients aged over 20 years, with a physical status of I–II (classified according to the American Society of Anesthesiologists), who were admitted for the management of a laryngeal mass, nodule or polyp. The exclusion criterion were as follows: presence of cardiovascular diseases, hypertension, diabetes mellitus, respiratory diseases, recent history of respiratory infection, allergy to local anaesthetics, usage of drugs which affect the cardio-circulatory or endocrine system, anticipated difficult intubation, more than two endotracheal intubation attempts, duration of anaesthesia over 30 minutes, and unplanned surgery outside the larynx.
A total of 99 patients, who were prepared for elective laryngoscopic procedures by the ENT surgery department of Ondokuz Mayis University Hospital, were enrolled in the study. Patients were randomly allocated to one of three groups: one group received 5 ml of 0.9 per cent IV physiological saline (physiological saline group; n = 33), one group received 1.5 mg/kg IV lignocaine (IV lignocaine group, n = 33) and another group received seven puffs of 10 per cent lignocaine aerosol sprayed onto the oropharyngolaryngeal structures (topical lignocaine group, n = 33). Calculated doses of lignocaine were diluted to 5 ml with physiological saline. In addition, 5 ml of physiological saline was injected in patients in the topical lignocaine group, and seven puffs of physiological saline were sprayed into the oropharyngolaryngeal structures of patients in the physiological saline and IV lignocaine groups.
Premedication was not given to the patients. One minute before the induction of anaesthesia, a resident, who was blinded to the contents of each vial, injected 5 ml of solution into all patients. Anaesthesia was induced with 1 µg/kg fentanyl and 2.5 mg/kg propofol, followed by 1.5 mg/kg succinylcholine (muscle relaxant). After muscle relaxation was achieved, seven puffs of aerosol were sprayed onto the patients' oropharyngolaryngeal structures (one puff each to the hard palate, oropharyngeal wall and root of the tongue, and two puffs each to the vallecula and larynx). This was achieved with the help of a laryngoscope, and was conducted by an anaesthetist blinded to the contents of each solution.
After ventilation with 100 per cent oxygen via a facemask for 2 minutes, endotracheal intubation was achieved using a Portex® microlaryngeal tube with an internal diameter of 5.0 or 6.0 mm. The cuff of the endotracheal tube was inflated until the cessation of air leakage around the tube during positive pressure ventilation at 30 cmH20. Maintenance of anaesthesia was achieved with 1–2 per cent sevoflurane in 60 per cent nitrous oxide in oxygen. Muscle relaxation was maintained by IV succinylcholine or mivacurium. Surgical excision of the polyp or nodule, or laryngeal biopsy, was performed by an ENT surgeon using a rigid suspension laryngoscope (8590 J; Karl Storz, Tuttlingen, Germany).
During anaesthesia, a standard monitoring device (Infinity Vista XL multichannel monitor; Draeger Medical Systems, Danvers, Massachusetts, USA) was used to non-invasively measure blood pressure and heart rate (HR). We also employed electrocardiography, pulse oximetry and capnography for monitoring. Mean arterial pressure, HR and peripheral oxygen saturation were recorded at the following time points: before the induction of anaesthesia (baseline/pre-induction); at 1 and 5 minutes after endotracheal intubation; and before, and at 1, 5 and 10 minutes after extubation. Percentage changes in mean arterial pressure and HR ratios were calculated with reference to the baseline values: percentage change = (actual value − baseline value) × 100 / baseline value.
At the end of the surgery, anaesthetics were discontinued and the patients were ventilated with 100 per cent oxygen. Extubation was performed following the observation of full recovery and arousal (e.g. eye opening or attempts at self-extubation), and the ability of patients to follow verbal commands. The duration of anaesthesia was recorded and lignocaine-related complications (such as local anaesthetic toxicity, aspiration and bradyarrhythmia) were noted.
A power analysis based on a previous study (in which mean arterial pressure values 5 minutes after endotracheal intubation were 117.7 ± 16.9 mmHg in the control group and 105.7 ± 15.6 mmHg in the 10 per cent lidocaine spray group) revealed that a sample size of 26 patients per group was required to achieve a power of 80 per cent and an alpha error of 0.05 for determining intergroup differences in mean arterial pressure values.Reference Lee and Park6
Statistical analysis was performed with SPSS for Windows software, version 16.0 (SPSS, Chicago Illinois, USA). Between-group analyses of normally distributed, continuous data were conducted using analyses of variance. Continuous data of uneven distribution were analysed with the Kruskal–Wallis test. Pairwise comparisons were performed using a Mann–Whitney U test with a Bonferroni correction. Data with a normal distribution curve were expressed as mean ± standard deviation values; data of uneven distribution were expressed as median (with minimum and maximum) values. A p value of less than 0.05 was considered as significant for all tests.
Results
In total, 99 patients were enrolled in the study. Eighty-seven cases were suitable for analysis according to the study protocol. Five cases were excluded because there were more than two endotracheal intubation attempts, four cases were excluded because of the extended duration of anaesthesia and three others were excluded as the patients required unplanned surgery outside the larynx. All groups were similar with regard to the number of cases, age of patients and duration of anaesthesia (Table I).
Table I Demographics and duration of anaesthesia
Data are expressed as mean ± standard deviation. IV = intravenous; min = minutes
The mean arterial pressure values were similar among the groups, at all the measurement time points (Table II). However, percentage changes in mean arterial pressure were higher in the physiological saline group than in the other groups at 1 minute after intubation (p = 0.13 and p = 0.04). The percentage changes in mean arterial pressure (at this time point) were greater in the topical lignocaine group than in the IV lignocaine group, but the finding was not significant (p = 0.46). Although the percentage changes in mean arterial pressure were generally of greater magnitude in the physiological saline group, there were no statistically significant differences between groups at other measurement time points (Table III).
Table II Mean arterial pressure data
Data are expressed as mean ± standard deviation. T1 = baseline, i.e. before anaesthetic induction (pre-induction); T2 = 1 minute after endotracheal intubation; T3 = 5 minutes after endotracheal intubation; T4 = immediately before extubation; T5 = 1 minute after extubation; T6 = 5 minutes after extubation; T7 = 10 minutes after extubation; IV = intravenous
Table III Percentage changes іn mean arterial pressure
Data are expressed as median (minimum; maximum). T2 = 1 minute after endotracheal intubation; T3 = 5 minutes after endotracheal intubation; T4 = immediately before extubation; T5 = 1 minute after extubation; T6 = 5 minutes after extubation; T7 = 10 minutes after extubation; IV = intravenous
The HR values in the groups were similar at all measurement time points (Table IV). Percentage changes in HR were of greater magnitude in the physiological saline and IV lignocaine groups than in the topical lignocaine group at 1 minute after intubation (p = 0.04 and p = 0.42, respectively). Although percentage changes in HR were generally higher in the physiological saline group, there were no statistically significant differences between groups at other measurement time points (Table V).
Table IV Heart rate data
Data are expressed as mean ± standard deviation. T1 = baseline, i.e. before anaesthetic induction (pre-induction); T2 = 1 minute after endotracheal intubation; T3 = 5 minutes after endotracheal intubation; T4 = immediately before extubation; T5 = 1 minute after extubation; T6 = 5 minutes after extubation; T7 = 10 minutes after extubation; IV = intravenous
Table V Percentage changes іn heart rate
Data are expressed as median (minimum; maximum). T2 = 1 minute after endotracheal intubation; T3 = 5 minutes after endotracheal intubation; T4 = immediately before extubation; T5 = 1 minute after extubation; T6 = 5 minutes after extubation; T7 = 10 minutes after extubation; IV = intravenous
Peripheral oxygen saturation was higher than 96 per cent at all measurement time points in all groups. No lignocaine-related complications were observed.
Discussion
Ten per cent lignocaine solution sprayed on the oropharyngeal and laryngeal structures, or the administration of 1.5 mg/kg IV lignocaine 2 minutes before endotracheal intubation, were found to attenuate the increases in arterial pressure and HR that occur in response to endotracheal intubation and suspension laryngoscopy.
The stimulation of laryngeal tissue triggers marked cardiovascular responses via the irritation of deep sensory receptors of the larynx during endotracheal intubation and laryngeal surgery.Reference Wenig, Raphael, Stern, Shikowitz and Abramson7 A fundamental aim in anaesthesia practice is to prevent the occurrence of cardiovascular responses to laryngoscopy, endotracheal intubation and surgical stimuli, in order to enhance patient safety. A high dose of anaesthetics, opioids, beta-blockers or alpha-2 agonists can be used for this purpose. However, their use may delay the time to arousal and the return of protective reflexes.Reference Pandazi, Louizos, Davilis, Stivaktakis and Georgiou8, Reference Matot, Sichel, Yofe and Gozal9
Many authors have recommended the use of lignocaine to prevent cardiovascular responses to laryngoscopy and endotracheal intubation.Reference Park, Bang, Choi, Hong, Kim and Yeong5, Reference Hamaya and Dohi10 It has been claimed that a 1.5 mg/kg dose of IV lignocaine can afford complete protection against cardiac arrhythmias of all types, and provide borderline protection against hypertension and tachycardia.Reference Abou-Madi, Keszler and Yacoub11 However, some authors have asserted that the topical application of lignocaine on orolaryngeal, laryngeal or laryngotracheal structures before the induction of anaesthesia is more effective in reducing, but not abolishing, the pressor response to laryngoscopy and endotracheal intubation.Reference Mostafa, Murthy, Barrett and McHugh12, Reference Sklar, Lurie, Ezri, Krichelli, Savir and Soroker13
Kim et al. compared lignocaine with remifentanil and found that, contrary to lignocaine, remifentanil was effective in attenuating the haemodynamic response during rapid sequence induction.Reference Kim, Shim, Kim, Ryu, Yoon and Jeon14 However, in that study, opioid was not administered in the lignocaine group, and the trachea was intubated immediately after lignocaine injection, without waiting for 2 minutes. Kyokong and Somboonviboon showed that 1.5 mg/kg IV lignocaine administered 2 minutes before intubation could attenuate the cardiovascular response to laryngoscopy.Reference Kyokong and Somboonviboon15 We created similar anaesthetic and analgesic effects in all patients with the aim of disclosing the additional effect of lignocaine.
Rigid suspension laryngoscopy can lead to the emergence of an additional pressor response. Laryngeal surgery with suspension laryngoscopy is associated with a higher rate of cardiac complications compared to other types of surgery.Reference Strong, Vaughan, Mahler, Jaffe and Sullivan1 In the present study, blood pressure measurements recorded 1 minute after endotracheal intubation were relatively reduced in the IV and topical lignocaine groups, but were increased in the placebo group. This finding indicates that lignocaine was effective in attenuating circulatory responses to laryngoscopy and endotracheal intubation. This effect might not be very important in patients with an American Society of Anesthesiologists' physical status of I–II, but it might be crucial in patients with hypertensive disease, myocardial ischaemia or cerebrovascular disease. Direct laryngoscopy via suspension laryngoscopy is widely used in patients with suspected cancer of the larynx. Chronic cardiac diseases are common in this group of patients given the advanced age of most patients and the prevalence of smoking; cardiovascular stability has vital importance for such patients.
Blood pressure values during surgery were higher in the placebo and IV lignocaine groups than in the topical lignocaine group. In other words, topical lignocaine aerosol prevented a marked rise in blood pressure during surgery; however, this finding was not statistically significant. This lack of significance might be the result of a severe but transient cardiovascular response to laryngoscopy and deep anaesthesia during surgery. These interventions last for a brief period of time, and, indeed, early arousal and the return of protective reflexes are very important. Therefore, the use of lignocaine in these patients may decrease the requirement for opioids and other anaesthetics.
It is important to determine the most efficient route of lignocaine administration. Gaumann et al. reported that patients treated with lignocaine had significant decreases in plasma adrenaline levels and did not suffer any significant rises in blood pressure and HR from baseline during rigid panendoscopy under general anaesthesia.Reference Gaumann, Tassonyi, Fathi and Griessen16 Lee and Park also indicated that the pre-operative application of 10 per cent lignocaine spray may be helpful in maintaining haemodynamic stability in patients undergoing laryngeal microscopic surgery performed with a suspension laryngoscope.Reference Lee and Park6 However, these authors did not compare topical and IV lignocaine administration routes. Furthermore, none of the previous studies investigated the effects of IV lignocaine on blood pressure and HR during laryngeal surgery conducted via a suspension laryngoscope.
• Suspension laryngoscopy is widely used for diagnosis and treatment of laryngeal disorders
• Endotracheal intubation and suspension laryngoscopy trigger abrupt, transient haemodynamic responses, resulting in undesirable side effects such as hypertension and tachycardia
• Intravenous and topical lignocaine were effective in attenuating haemodynamic responses to endotracheal intubation and short-term laryngeal surgery conducted via a rigid suspension laryngoscope
Although both routes of lignocaine administration were effective in preventing blood pressure increases in the present study, topical lignocaine application resulted in greater decreases in mean arterial pressure relative to the IV route. The reason for this initial decrease in mean arterial pressure in the topical lignocaine group might be related to the depressant effects of anaesthetic drugs, which may effectively prevent the stimulation of tissues induced by laryngoscope use. Of course, this finding would be an advantage in patients who require low doses of anaesthetic drugs. In addition, the topical application of lignocaine appeared to be more effective in preventing an increase in HR, although there was no statistically significant difference between the findings of the topical lignocaine group and those of the other treatment groups. Furthermore, topical application requires two manipulations and IV application is more practical. Each patient must be evaluated individually for the selection of these two alternative routes of administration.
Lignocaine-related complications can discourage surgeons from using this medicine. Local anaesthetic toxicity is the most detrimental of these complications. In addition, aspiration may be developed due to loss the function of swallowing on topical use and bradyarrhythmias on IV use. Nevertheless, these side effects all develop as a result of high dosages. The doses used in this study (70 mg topical and 1.5 mg/kg IV) were safe for adults and we did not observe any side effects.
In conclusion, the IV or topical administration of lignocaine was effective in attenuating the haemodynamic responses to laryngoscopy and endotracheal intubation during the induction of anaesthesia (performed for short-term laryngeal surgery) conducted via a rigid suspension laryngoscope.
Acknowledgements
The authors wish to thank the medical staff of the departments of anaesthesiology, reanimation and ENT surgery of Ondokuz Mayis University Hospital who were involved in the study (conducted between May 2006 and November 2010) for their invaluable clinical assistance and co-operation. The authors also wish to thank Dr Erhan Cetin Cetinoglu for the biostatistical evaluation and Dr Gurkan Kazanci for editing the language of the manuscript. All financial and material aspects of this research were funded by the Department of Anaesthesiology research funds, Ondokuz Mayis University, Turkey.
