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ORIGINAL ARTICLE
Year : 2023 | Volume
: 24
| Issue : 1 | Page : 49-53
Evaluation of effect of dexamethasone and bicarbonate as adjuvants to intracuff lignocaine on endotracheal tube tolerance during emergence and incidence of postoperative cough and sore throat
Muazzam Hasan1, Atif Javed2, Kali Charan Das1, Ashish Bindra1
1 Department of Neuroanaesthesia and Critical Care, AIIMS, New Delhi, India
2 Department of Anesthesiology, Jawaharlal Nehru Medical College, Aligarh, Uttar Pradesh, India
Correspondence Address:
Dr. Kali Charan Das
AIIMS, New Delhi
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/TheIAForum.TheIAForum_8_23
Background: Smooth uneventful extubation and prevention of postoperative complications such as cough and sore throat adds to the quality of perioperative care and patient outcome. This study was designed to compare tube tolerance and hemodynamics during extubation, as well as the incidence of postoperative cough and sore throat, in patients operated under general anesthesia of more than 2-h duration.
Materials and Methods: This prospective double-blinded, randomized controlled study included 100 patients posted for elective surgical procedures with expected duration of more than 2 h, under general anesthesia. Patients were divided randomly into two equal groups, namely Group A and Group B. In Group A, endotracheal tube (ETT) cuff was filled with lignocaine with sodium bicarbonate as an adjuvant, while in Group B, dexamethasone was added as an adjuvant to intracuff lignocaine. ETT tolerance at the time of extubation was recorded and compared. Other parameters such as rate pressure product, volume of drug diffused through cuff, and incidence of postoperative cough and sore throat were also compared. Data analysis was done using unpaired t-test and Chi-square test as appropriate, where P < 0.05 was considered statistically significant.
Results: Eighty-two percent of patients in Group A while 78% of patients in Group B were categorized as tube tolerant during extubation (P = 0.62). The incidence of postextubation sore throat at 1 h was 30% versus 16% (P = 0.09) while at 24 h was 20% versus 6% (P = 0.03) in Group A and Group B, respectively. The incidence of cough postextubation at 1 h was 6% versus 0 (P = 0.07) while at 24 h was 18% versus 4% (P = 0.02) in Group A and Group B, respectively. The volume of intracuff drug diffused during anesthesia was 0.71 ± 0.27 (mean ± standard deviation [SD]) ml in Group A and 0.5 ± 0.23 (mean ± SD) ml in Group B (P = 0.02). Majority of patients (>85%) in both the groups remained hemodynamic stable during emergence with no statistical difference between the groups.
Conclusion: Both bicarbonate and dexamethasone as an adjuvant to 2% intracuff lignocaine offer smooth emergence in terms of tube tolerance and hemodynamic stability during extubation. However, dexamethasone when used as an adjuvant has a better effect on prevention of development of postoperative cough and sore throat.
Keywords: Dexamethasone, emergence, endotracheal tube tolerance, intracuff alkalinized lignocaine, postoperative cough and sore throat
To counter the extubation response, different techniques as well as pharmacological agents are used. Intravenous drugs such as opioids, lignocaine, esmolol, dexmedetomidine, propofol, and magnesium are given; however, drugs have their own complications, specifically sedative effects that may delay the awakening and recovery of the patient.[1],[2] Endotracheal tube (ETT) intolerance during emergence can lead to bronchospasm, laryngospasm, hemodynamic instability as well as other undesirable complications.[1],[3] Another important factor that should be taken into consideration is ETT cuff pressure over the tracheal wall. Literatures have shown a direct relationship between the incidence of development of postoperative cough-sore throat and ETT cuff pressures.[4],[5] Despite optimal air filling in ETT cuff using manometer, studies have reported an increase in intracuff pressure due to diffusion of nitrous oxide inside ETT cuff slowly over the time in long-duration surgeries.[6],[7]
This problem led the clinicians to use liquids instead of air for filling ETT cuff. Recently, multiple independent studies have shown beneficial outcomes of using lignocaine for filling ETT cuff instead of air in patients undergoing general anesthesia.[6],[7],[8] Intracuff lignocaine microdiffusion through ETT cuff anesthetizes the tracheal mucosa and has a smoothening effect which improves tube tolerance during extubation.[8]
Both bicarbonate and dexamethasone are being used routinely as adjuvants to lignocaine to potentiate its overall local anesthetic effect. This study was designed to evaluate and compare the effects of using either sodium bicarbonate or dexamethasone as adjuvants to intracuff lignocaine on ETT tolerance during emergence which was the primary outcome of this study. Occurrence of sore throat and cough as well as parameters such as hemodynamic response at extubating, amount of drug diffused through ETT cuff were also compared between the two groups.
Materials and MethodsThe study was approved by the institutional ethical committee and subsequently was registered in clinical trial registry (Registration No. [NCT03833947]). This prospective randomized controlled trial, over 6 months, included 100 patients in the age group of 18–60 years with American Society of Anesthesiologists (ASA) Class I and II, posted for elective thoracoabdominal surgeries such as laparoscopic hernia repair, laparotomy bowel surgery, modified radical mastectomies, and laparoscopic nephrectomy with expected duration of general anesthesia of more than 2 h. Patients with ASA III and IV, cardiovascular morbidities, and known drug allergy and pregnant patients were excluded from the study. Patients were divided into two groups randomly according to chit-in-box method, namely Group A and Group B, with 50 patients in each group. For patients of Group A, a mixture of 7.5% sodium bicarbonate with 2% lignocaine in the proportions of 0.5:9.5 ml (total 10 ml) was prepared in a 10 ml syringe, while for Group B, a mixture of dexamethasone (2 ml vial containing 4 mg/ml dexamethasone) with 2% lignocaine in the proportions of 0.5:9.5 ml (total 10 ml) was prepared. Preparation of drug mixture for endotracheal cuff filling as per the group assigned was done by a separate person not involved in the perioperative management of the patient. The syringe was labeled as ETT cuff and was handed over to an anesthesiologist managing the operation theater. Cases were done under general anesthesia with epidural analgesia as per the same institutional protocol in patients of both the groups. Patients were premedicated with intravenous midazolam 0.03 mg/kg, and fentanyl 2 μg/kg. Following preoxygenation, anesthesia was induced with propofol (2–2.5 mg/kg) and muscle relaxation was achieved with vecuronium bromide (0.08–0.12 mg/kg). After obtaining complete relaxation, as reflected by train-of-four response, intubation was performed. In both the groups, cuff of the ETT was slowly filled with the prepared drug mixture until no leak was heard during the peak airway pressure of the ventilator cycle while auscultating the trachea. Patients were maintained on oxygen, nitrous, isoflurane, intermittent vecuronium, and epidural infusion of 0.125% bupivacaine. At the end of surgery, epidural infusion was continued and anesthetic gases were stopped. Patients were kept on 100% oxygen on pressure support mode with apnea backup. Reversal agent was given when train-of-four ratio value reached >0.7. Extubation was performed when patient achieved train-of-four ratio of more than 0.9. Tube tolerance at the time of extubation was observed and categorized as per Minogue scale by the attending anesthesiologist [Table 1].[9] The incidence of sore throat (presence of hoarseness/husky voice) and cough (present/absent) was also recorded at 1 h and 24 h postextubation. Hemodynamic stability at the time of extubation was recorded in terms of rate pressure product (RPP = product of systolic blood pressure [mmHg] and heart rate [beats per min]). RPP at the end of surgery when anesthetic agents were stopped was taken as baseline and then recorded at intervals of 5 min up to 15 min postextubation. The volume of drug mixture in the cuff was noted at the start and end of surgery to determine the volume of drug absorbed through ETT cuff. The total duration of anesthesia was also noted in both the groups.
Table 1: Modified Minogue scale to be used for analysis during emergence and outcome categorization for the primary outcome analysisStatistical analysis
The sample size was calculated with the help of sample size power calculator for binary outcome equivalence trial.[10] On the basis of data from our pilot study, 88% of patients were categorized as tube tolerant during emergence. For an equivalence trial, taking more than 20% difference as a clinically significant difference with Type I error of 0.05 and power equal to 80%, a sample size of 46/group was required. We took a total sample size of 100 patients to avoid attritions and loss of follow-up.
Data were recorded and entered into Microsoft Excel 2013. Statistical analysis of data was done using the Statistical Package for the Social Sciences (SPSS) version 16 (SPSS Inc. Released 2007, SPSS for Windows, version 16.0. Chicago, Illinois, USA). Data regarding age, weight, duration of anesthesia, hemodynamic variation, and volume of intracuff drug absorbed were analyzed using unpaired t-test. Gender ratio, ASA grade, postoperative cough and sore throat, and grades of extubation were analyzed using Chi-square test. For all statistical analyses, P < 0.05 was considered statistically significant.
ResultsAll hundred patients completed the study. Demographic parameters such as age, weight, sex ratio, American Society of Anesthesiologists grading, and duration of anesthesia were comparable in both the groups [Table 2]. There were no attritions, nonconsent, and dropouts from the study. As shown in [Table 3], 82% of patients in Group A while 78% of patients in Group B were categorized as tube tolerant during extubation (P = 0.62). The incidences of postextubation sore throat at 1 h were comparable in both the groups (30% vs. 16%; P = 0.09), but after 24 h, Group B had a significantly lower incidence of sore throat (20% vs. 6%; P = 0.03) [Figure 1]. The incidence of cough postextubation at 1 h was 6% versus 0 (P = 0.07) and after 24 h was 18% versus 4% (P = 0.02) in Group A and Group B, respectively [Figure 2]. The volume of intracuff drug diffused during anesthesia was 0.71 ± 0.27 (mean ± standard deviation [SD]) ml in Group A and 0.5 ± 0.23 (mean ± SD) ml in Group B (P = 0.02). More than 85% of patients in both the groups remained hemodynamic stable during emergence (changes in hemodynamic parameters at the time of extubation were well within 20% of the preextubation values), with no statistical difference between the groups.
DiscussionThe use of cuffed ETT is standard practice in general anesthesia. However, a range of complications such as tracheal mucosal ischemia, edema, inflammation, ulceration, and tracheal stenosis are often related to pressure effects of ETT cuff on tracheal mucosa. Above optimal cuff pressure also lead to postoperative cough, sore throat, hemodynamic changes, and unpleasant emergence.[11] Postoperative cough can lead to adverse surgical outcome, especially after neurosurgery, hernia repair, laparotomy procedures, etc.
Maintenance of ideal cuff pressure during prolonged surgery is very challenging. Various factors such as use of nitrous oxide, agent filled in the cuff, material, and type of ETT cuff govern it. Nitrous oxide and oxygen readily diffuse into ETT cuff leading to gradual rise in intracuff volume and thereby pressure on tracheal mucosal wall.[11] Previous studies have shown that liquid ETT cuff inflation media such as 2% lignocaine, dexamethasone, and saline are better than air in terms of postoperative airway complications after general anesthesia.[5],[6],[8]
Lignocaine being liquid in nature not only inhibits the entry of N2O in the cuff but also permeates through semipermeable cuff membrane to tracheal mucosa and provides direct anesthetic effect. In experimental studies in vitro, it was demonstrated that increasing the nonionized fraction of the local anesthetic, by adding sodium bicarbonate, results in increased penetration of lignocaine through cuff membrane.[12] In our study, the average duration of anesthesia was more than 200 min in both the groups; this duration might have been enough for lignocaine microdiffusion in both the groups and therefore ETT tolerance at the time of extubation did not show any significant difference between the groups.
The incidences of postoperative cough and sore throat at 24 h were found to be significantly lesser in patients belonging to Group B where dexamethasone was used as an adjuvant to intracuff lignocaine. Pharmacological properties of dexamethasone can explain the above findings. Dexamethasone owing to its anti-inflammatory activity, which includes inhibition of leukocyte migration, maintenance of cell membrane integrity, attenuation of lysosome release, and reduction of fibroblast proliferation, might have led to decreased tracheal mucosa edema and thereby postoperative cough and sore throat. Similar findings were reported in a study conducted by Desai et al.[8] However, Choubsaz et al. studied the effect of adding dexamethasone to 2% intracuff lignocaine but found no significant benefit over intracuff lignocaine alone.[13]
In both the groups, the incidence of unwanted hemodynamic response during emergence was low. Only five patients of Group A and seven patients of Group B had episodes of hypertension and tachycardia during emergence that required medical treatment [Table 3]. All were treated with titrated doses of intravenous esmolol. The rest of the patients of both the groups had hemodynamic parameters well within 20% of the preextubation values and did not require any active intervention [Figure 3]. Local effect of intracuff drug on tracheal mucosa postmicrodiffusion must have prevented the undesired hemodynamic response during emergence which is otherwise commonly seen in awake extubation.
Another important concern regarding filling of ETT cuff with a liquid agent is risk of accidental rupture of cuff and spillage of liquid into the trachea. This apprehension is less with lignocaine, as even in such accidental spillage into the trachea, lignocaine should not cause harm as it is one of the drugs which can be given through tracheal route.
ConclusionBoth bicarbonate and dexamethasone as an adjuvant to 2% intracuff lignocaine offer smooth emergence in terms of tube tolerance and hemodynamic stability during extubation. However, dexamethasone when used as an adjuvant has a better effect on prevention of development of postoperative cough and sore throat.
Limitations
The findings of this study may not relate to short-duration surgeries. Microdiffusion of lignocaine through polyvinyl chloride ETT cuff takes time and thus overall effect on tracheal mucosa comes only after prolonged exposure. Furthermore, we did not measure intracuff pressure as manometer available with institute was recommended only for measuring air pressures of ETT cuff.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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