|Year : 2020 | Volume
| Issue : 3 | Page : 184-188
Evaluation of nebulized lignocaine versus intravenous lignocaine for attenuation of pressor response to laryngoscopy and intubation
Priya Ganesan, Hemavathy Balachander, Lenin Babu Elakkumanan
Department of Anaesthesiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
|Date of Submission||06-Apr-2020|
|Date of Decision||19-Apr-2020|
|Date of Acceptance||28-Apr-2020|
|Date of Web Publication||10-Jul-2020|
Dr. Priya Ganesan
Department of Anaesthesiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry
Source of Support: None, Conflict of Interest: None
Background: Laryngoscopy and intubation form an indispensable step in general anesthesia. They elicit significant sympathoadrenal responses. Suppression of these responses forms an essential step in general anesthesia. The aim of our study is to compare the efficacy of nebulized lidocaine versus intravenous (IV) lidocaine in suppressing the pressor response to laryngoscopy and intubation. Materials and Methods: One hundred patients within the age group of 18–65 years undergoing elective surgery under general anesthesia were randomly allocated into two groups: group IV lignocaine (IVL) (n = 50) and group nebulized lignocaine (NL) (n = 50). Baseline values of heart rate (HR), systolic blood pressure (BP), diastolic BP, mean arterial pressure (MAP), and saturation were noted. Patients received either nebulized or IV lidocaine according to the group. HR, saturation, BP, MAP, and arrhythmias were noted every minute from laryngoscopy up to 5 min postlaryngoscopy and intubation. Results: There was an increase in HR and BP from baseline in both the groups with laryngoscopy and intubation, and the increase is significantly less in NL (P < 0.05). The parameters in both the groups attained the baseline values at the 3rd min postintubation. However, the 4th- and 5th-min readings showed values below baseline in the nebulization group. Conclusion: This study suggests that NL may be more effective than IVL in suppressing pressor response to laryngoscopy and intubation.
Keywords: Intravenous lignocaine, intubation, intubation, laryngoscopy, lignocaine
|How to cite this article:|
Ganesan P, Balachander H, Elakkumanan LB. Evaluation of nebulized lignocaine versus intravenous lignocaine for attenuation of pressor response to laryngoscopy and intubation. Curr Med Issues 2020;18:184-8
|How to cite this URL:|
Ganesan P, Balachander H, Elakkumanan LB. Evaluation of nebulized lignocaine versus intravenous lignocaine for attenuation of pressor response to laryngoscopy and intubation. Curr Med Issues [serial online] 2020 [cited 2020 Oct 21];18:184-8. Available from: https://www.cmijournal.org/text.asp?2020/18/3/184/289419
| Introduction|| |
Despite adequate anesthetic depth, direct laryngoscopy and intubation which are essential steps in general anesthesia needing endotracheal intubation elicit a significant adreno-sympathetic response. This response, as manifested by increased systolic blood pressure (SBP), diastolic BP (DBP), mean blood pressure (BP), heart rate (HR), arrhythmias, etc., would result in unacceptable morbidity and mortality in patients with compromised and borderline cardiac reserve. This has necessitated the use of various adjuvants such as opioids, beta-blockers, nitroglycerine, nitroprusside, lignocaine, and magnesium sulfate, with varying degrees of effectiveness. Nebulized lignocaine (NL), a novel method to prevent this response, has rekindled interest in the recent past. Aerosol anesthesia is a method that has been rather widely used for bronchoscopy and bronchography. Hence, this study was designed to compare the effectiveness of NL as against intravenous (IV) lignocaine (IVL), which has proven effectiveness in preventing the response to laryngoscopy.
Aims and objectives
Evaluation of efficacy of the NL as compared to IVL in:
- Suppressing pressor response to laryngoscopy and intubation
- Suppression of arrhythmias if any during laryngoscopy and intubation.
| Materials and Methods|| |
The present study was conducted after obtaining the Institutional Ethics Committee approval on adult patients admitted to Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER). Written informed consent was obtained from all patients.
- Adult American Society of Anesthesiologists (ASA) 1 and 2 patients posted for surgery under general anesthesia requiring endotracheal intubation.
- Patients aged between 18 and 65 years.
- Patients with preexisting hypertension
- Patients with known allergy to the study drug or contraindication to any of the administered drugs
- Patients with anticipated difficult airway.
1. Baseline parameters and
- Changes in SBP, DBP, and mean BP at 1, 2, 3, 4 up to 5 min after laryngoscopy and intubation
- Changes in HR at similar time intervals
- Arrhythmias noted if any during laryngoscopy and intubation
- Adequacy of gag, cough, and swallowing at extubation.
Patients admitted to JIPMER and posted for elective surgery requiring general anesthesia with endotracheal intubation had formed the study population. After applying exclusion criteria, 100 ASA 1 and 2 patients were included. A 20% reduction in SBP rise with nebulization as compared to IVL was taken as the primary outcome measure, and the sample size was calculated with an α error of 5% and β error of 20%. These patients (n = 100) were then randomized to either IVL or NL group by opaque sealed envelope.
After preanesthetic evaluation, all patients were premedicated with tablet famotidine 20 mg, tablet metoclopramide 10 mg, and tablet diazepam 10 mg 2 h before surgery, followed by injection morphine 0.1 mg/kg intramuscularly 1 h before surgery. On arrival at the operation theatre, monitors including non invasive blood pressure (NIBP), electrocardiograph (ECG), and oxygen saturation (SpO2) were connected. Baseline values of HR, SBP, DBP, mean arterial pressure (MAP), and saturation were noted. Patients in the NL group were nebulized with 8 ml of 2% lignocaine for 20 min, and patients in the IVL group were given O2 through the nebulizer. Injection fentanyl 2 μg/kg was given to both the groups. Following this, thiopentone 5 mg/kg was given till the loss of eyelash reflex. After checking the adequacy of mask ventilation with 100% O2, either lignocaine 1.5 mg/kg in 10 ml of saline or 10 ml of saline was given to the patients depending on the group. Suxamethonium 1.5 mg/kg was given in both the groups after 30 s of lignocaine administration. Mask ventilation with 100% O2 was continued for 60 s, and then, laryngoscopy was attempted by anesthetists not involved in the study using an appropriate size laryngoscopy blade. Intubation was done using an appropriate size cuffed endotracheal tube, and cuff was inflated with appropriate amount of air. The position of the tube was confirmed by auscultation for bilateral air entry and observing the capnogram.
HR, SBP, MAP, and DBP were monitored by an automated BP cuff before induction (baseline values) and then at 1-min interval up to 5 min after intubation. Arrhythmias if any and the type of arrhythmia were also noted.
Anesthesia was maintained with 66% N2O in O2 and isoflurane. Morphine and vecuronium were given as per the patient requirement, and the lungs were ventilated with a tidal volume of 10 ml/kg and respiratory rate of 10/min. End operatively after reversal, check laryngoscopy was done to ensure the adequacy of gag, cough, and swallowing reflex, and then, trachea was extubated.
Method of statistical analysis
Data (parametric) were expressed as mean ± standard deviation, and all parameters were analyzed using windows SPSS 16 version.
- Parametric variables between the groups were studied using Student's test
- Nonparametric variables were analyzed using Chi-square test
- P < 0.05 was considered as statistically significant.
| Observation and Results|| |
Our study was conducted in 100 adult patients who underwent elective surgery under general anesthesia in JIPMER during November 2009–July 2011 after they fulfilled the inclusion and exclusion criteria. Patients were randomly allocated into two groups: group IVL (n = 50) and group NL (n = 50) using the sealed envelope. All patients (n = 100) enrolled in the study successfully completed the procedure. [Table 1] shows the mean age, weight, and gender in both the groups. The age, weight, and gender were comparable between the two groups. [Table 2] shows the baseline parameters HR, SBP, MAP, DBP, and oxygen saturation between the two groups. The baseline parameters were comparable between the two groups. [Figure 1] shows the mean change in HR over time between the two groups. The trend in HR changes within the group and in between the two groups was similar at all the time intervals. There is a minimal increase in HR from baseline in both the groups. The increase in HR at intubation was more with IVL compared to NL which was statistically significant (P < 0.05). The HR attained the baseline values at the 3rd min postintubation. [Figure 2] shows the mean changes in SBP over time between the two groups. There was a significant difference in SBP between the groups at intubation. The SBP has increased from the baseline significantly in the group IVL as compared to the group NL which attained the baseline values by about the 3rd min postintubation. At the 4th and 5th min, mean SBP was lower with NL compared to IVL. [Figure 3] shows the mean DBP changes between the two groups. There is an increase in the DBP from baseline in both the groups which returned to baseline by the 2nd min postintubation. The increase in DBP was more with IVL at intubation. [Figure 4] represents the MAP changes between the two groups. There is an increase in the MAP from baseline in the group IVL, but there is no significant rise in the group NL (P < 0.05). At the 4th and 5th min, MAP was lesser with NL as compared to IVL.
|Figure 2: Mean changes in the mean systolic blood pressure over time between the two groups.|
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|Figure 3: Mean changes in the mean diastolic blood pressure over time between the two groups.|
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|Figure 4: Mean changes in the mean arterial pressure over time between the two groups.|
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Events and complications
Two patients (4%) in IVL had transient atrial ectopics at laryngoscopy and intubation as compared to none in NL. Postextubation, none of the patients had inadequate cough, gag, or swallowing reflex.
| Discussion|| |
Laryngoscopy and tracheal intubation elicit a significant sympathoadrenal response. In certain groups of patients, such as those who are at risk for developing arterial hypertension or myocardial ischemia, such changes may be detrimental. The precise mechanism of this sympathoadrenal response is unclear but probably due to intense stimulation of the upper respiratory tract. Suppressing a hypertensive response to intubation is one of the important prerequisites for a properly administered general anesthesia. Stoelting found that short-duration laryngoscopy (ideally <15 s) is an effective method to minimize increase in MAP during endotracheal intubation. Drugs such as inhalational agents, narcotics, β-blockers, α-blockers, calcium channel blockers, and vasodilators have been used to suppress these responses. Intubation in a deeper plane also alleviates this response. Unfortunately, they can be ineffective or have adverse effects including bradycardia and hypotension. In our study, we used lignocaine, an amide local anesthetic to blunt the hemodynamic response during laryngoscopy and intubation.
Lignocaine has been used in various modalities such as IV, topical, instillation, or inhalation. Each route has its own merits and demerits. In our study, our primary aim was to compare the effectiveness of IVL versus NL for suppression of hemodynamic response to laryngoscopy and intubation.
We conducted this study on 100 ASA I and II patients undergoing elective surgery under general anesthesia requiring laryngoscopy and intubation. We administered lignocaine by either nebulization (2%) or IV route. Aerosolized lignocaine was selected rather than intratracheal instillation to avoid two laryngoscopies which might confound the results. The mean age, weight, and sex of the patients between the two groups were comparable.
IVL may suppress circulatory responses to tracheal intubation by increasing the depth of general anesthesia. Himes et al. found that lignocaine blood levels of 3–6 μg/ml were found to potentiate the effects of N2O anesthesia in humans and 10%–28% reduction in the MAC of halothane. Bromage and Robson studied blood levels of lignocaine after various modes of administration and endorsed that systemic absorption of lignocaine obtunds laryngeal reflexes. NL acts both by topical anesthesia of the airway and by increasing the depth of anesthesia by systemic absorption and its effects can be potentiated by the use of antisialogogues. It is a very effective surface anesthetic causing rapid absorption from mucosal surface. The peak blood concentration is achieved within 4–15 min after instillation. Given intravenously, peak blood levels are achieved in 1.5 min.
The patients in the IVL group were given 1.5 mg/kg of lidocaine 90 s before laryngoscopy and intubation. Bedford et al. in their study showed that administration of lignocaine 1.5 mg/kg about 1.5 min produces a mean blood lidocaine level of 3.2 μg/ml before laryngoscopy and intubation which had sufficiently prevented cardiovascular response. In our study, patients were nebulized using a standard gas-driven nebulizer with 8 ml of 2% lignocaine 20 min before attempting laryngoscopy.
NL has been used successfully as a sole technique for airway instrumentation. The concentration of 2% lidocaine was chosen for nebulization in our study as compared to the other studies which used 4% lignocaine. At 4% concentration, there may be delay in return of airway reflexes if surgery is completed in less than an hour. Hence, this study is designed to evaluate the efficacy of nebulization of lesser concentration of lignocaine (2%) in attenuating the pressor response to laryngoscopy and intubation.
The dose of 8 ml was chosen in order to ensure comparability between the two groups. It is suggested that 50% of the mists were lost around the patient mouth during expiration and breath-holding. Chinn et al. have established that loss of local anesthetic to air varies from 20%, if nebulization was cycled with respiration, to 50% or greater when nebulization was continuous during inspiration and expiration. As our technique employs continuous nebulization, the estimated loss of NL is likely to be >50%, further lessening the plasma concentration and ensuring comparability in the mean lignocaine concentrations (75 mg) between the two groups.
The present data demonstrate that there is no increase in hemodynamic variables from the baseline in the nebulized group as compared to the IVL group (P < 0.05). The magnitude of pressor response SBP and MAP was significantly greater in the IVL group compared to the nebulized group immediately after intubation at 1 min, but both the groups attained their baseline by the 3rd min. There is a significant increase in DBP in both the groups. Our data with IVL were comparable to those of Splinter, Miller et al., and Chraemmer-Jørgensen et al. who found that IVL given 1, 2, 3, or 4 min before laryngoscopy did not attenuate the pressor response., Venus et al. reported significantly greater cardiovascular stability after laryngoscopy and intubation in patients pretreated with aerosolized lignocaine (240 mg) than that of a control group which received aerosolized saline.
In our study, we did not have any significant fall in oxygen saturation throughout the study period in both the groups. Two out of 50 patients (4%) in the IVL group developed arrhythmias which were transient atrial ectopics as compared to the NL group, where none of the patients had arrhythmias. Reid and Bruce in their study recognized that irritation of any kind, particularly that of mechanical agents into the respiratory tract, initiates pulmono-cardiac reflexes (vasovagal). Abou-Madi et al. opined in their study that the arrhythmia-suppressant effect of the aerosol was partly due to systemic absorption of lignocaine.
The nebulization procedure was well tolerated by the patients, and all patients enrolled in the study completed the nebulization procedure. A few patients in the NL group experienced sore throat during the period of nebulization and also complained of hoarseness of voice at the end of nebulization. All patients were examined at extubation with check laryngoscopy for adequacy of cough, gag, and swallowing reflex. There were no such adverse events in either of the groups.
We did not measure lignocaine blood levels in this study. Ideally, it would be desirable to correlate the clinical effect of lidocaine with plasma levels. However, such a correlation may not be appropriate because the mechanism by which IV lidocaine acts is still unclear. In addition to this, plasma levels may not necessarily reflect tissue levels. Pelton et al. found plasma lignocaine concentrations of about 2.7 μg/ml in children after topical aerosol application of lignocaine (3 mg/kg), which were far below the toxic levels of lignocaine (5 μg/ml).
All patients in our study received morphine intramuscular (IM) and fentanyl IV as per our departmental protocol. The use of fentanyl before induction may have had a significant influence in attenuation of pressor response in both the groups. Despite this, the nebulization group had a tendency toward a lesser and more transient rise in BP, and this suppression, though not very useful in normotensive individuals, may be very useful in hypertensive or patients in whom fentanyl doses need to be curtailed.
In our study, the effectiveness of NL for suppressing pressor response to laryngoscopy and intubation was well documented. Local anesthesia was achieved with 2% lignocaine, and the subjects tolerated nebulization well. Thus, we recommend the use of their lesser concentration and dose of NL for effective suppression of hemodynamic response to airway instrumentation.
The limitations of our study are as stated herewith – not being able to measure plasma lignocaine concentrations, effect of lignocaine on other organ systems such as suppression airway reactivity and reduction of intracranial hypertension, and not noting duration of laryngoscopy on hemodynamic response. However, all our study patients had successful intubation at the first attempt. Our study was done in normotensive individuals, and the extrapolation of our results in hypertensive individuals needs further evaluation.
| Conclusion|| |
This study suggests:
- NL is more effective than IVL in suppressing pressor response to laryngoscopy and intubation
- NL appears to be more effective in suppressing arrhythmias occurring during laryngoscopy and intubation as compared to IVL.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
Research quality and ethics statement
This study was approved by the Institutional Review Board prior to the commencement of the study, (IRB Min no: DME/34/ED dated 8th March 2010). Patient confidentiality was maintained using unique identifiers and by password protected data entry software with restricted users.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]