Endotracheal intubation (ET) is an age-old technique and was first described by Hippocrates (460-380 BC) in Greece.1 Airway management with cuffed endotracheal tube in General Anaesthesia is an important part of an anaesthesiologist’s responsibilities towards patient.

ET helps to prevent the aspiration of gastro-pharyngeal contents, to provide positive pressure ventilation and to administer inhalational anesthetic gases.2 In order to achieve these, an airtight seal is created by inflating the cuff close to the distal tip of the ET tube (ETT) with air. It is necessary to have a sufficiently high cuff pressure to achieve an adequate seal of airway with the endotracheal tube cuff.3 Endotracheal tube (ETT) cuff pressure management is an essential part of airway management in intubated and mechanically ventilated patients. The ETT cuff should be inflated in order to seal the airway without volume loss or pharyngeal content aspiration. However, the pressure exerted on the trachea must be maintained within a therapeutic range (25 - 30 cmH2O or 18 - 22 mmHg) that is high enough to ensure delivery of mechanical ventilation and prevention of marked aspiration, but low enough to ensure perfusion to the tracheal capillaries without causing injury.4,5 Apart from maintaining correct cuff pressure, it is important to perform cuff pressure measurements at 6 - 12- hourly intervals and to use the correct method.

Evidence-based guidelines can be used to reduce inappropriate variations in clinical practice and discourage practices lacking convincing or sufficient evidence of effectiveness.6 The Nesibopho Best Practice Guideline provides recommendations for tracheal tube cuff pressure monitoring in nursing care practice. Catastrophic consequences of ETT cuff over inflation and insufficient inflation are reported. The ETT cuff pressure must be in a range that ensures delivery of the prescribed mechanical ventilation tidal volume, reduces the risk for aspiration of secretions that accumulate above the cuff without compromising the tracheal perfusion. A cuff pressure of 20–30 cm of water is recommended for the prevention of aspiration.7-8

Post intubation sore throat is a common side effect of general anesthesia. This may partly result from ischemia of the oropharyngeal and tracheal mucosa due to over‑inflation of the cuff.

Postoperative sore throat (POST) being the most undesirable symptom occurs in more than 50% of surgical patients.9 Among the various methods of airway management such as the use of facial mask, laryngeal mask airways, and endotracheal tube (ETT), ETT is most frequently associated with such postoperative complications ranging from 30% to 70%.10-11 The cause of these morbidities could be either patient's bucking or coughing or friction between the tracheal mucosa or increase in ETT cuff pressure during general anesthesia. Various literature in the past has proven the relation of rise in cuff pressure and volume with the usage of N2O. Intracuff use of saline and lignocaine is recently being reviewed for the effectiveness in preventing coughing, POST, and postoperative hoarseness (PH).12

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. Anaesthetic activity is dependent on having both the ionised and non-ionised forms of the drug present after injection. Alkalinisation increases the proportion of non-ionised drug and this could be advantageous.

Alkalinization of lignocaine with sodium bicarbonate (NaHCO3) increases the nonionized form of lignocaine which considerably increases the diffusion of lignocaine through polyvinyl cuff walls (63 folds). Thus, lesser amount of lignocaine can provide rapid and prolong action over mucosa.13

When alkalinized lignocaine is instilled in the cuff, it prevents the increase of cuff pressure. Alkalinized lignocaine is more permeable and has additional anaesthetic property. Both in-vivo and in-vitro studies have been conducted on endotracheal tube cuffs filled with lignocaine. Recent study14 showed alkalinised lignocaine instilled into the cuff of intubated patients undergoing general anaesthesia decreases the extubation response and the immediate postoperative airway morbidity.

The primary objective of this study was to compare alkalinized lignocaine, plain lignocaine or air is better for intubated patients and its effect on post intubation morbidities by inflating endotracheal tube cuff with lignocaine or alkalinised lignocaine in place of air.

A prospective, randomized, double blind study was undertaken for comparative evaluation of prevention of post intubation morbidity by inflating endotracheal cuff with air vs lignocaine vs alkalinised lignocaine. 90 patients were divided into following three groups of 30 patients:

Group A:   ETT cuffs inflated with Air

Group B:   ETT cuffs inflated with plain lignocaine (preservative free)

Group C:   ETT cuffs inflated with alkalinized lignocaine

Study design:

 A prospective, randomized, double blind study

Study Duration: 18 months

Study area: The study was done at our tertiary care centre in the department of Anesthesiology on attending OPD/IPD.

Study population: All patients undergoing elective surgical procedures of duration more than two hours under general anaesthesia with endotracheal intubation at our Tertiary care Hospital who fulfilled the inclusion criteria.

Sample size: 90 patients

With reference to the study of Estebe JB et al15 which noted that the difference of proportion of hoarseness of voice between the groups was 70%, sample size was calculated using the formula:

n = 2(Za +Zb)2 p(1-p) / (p1-p2)2

a =alpha error: 5%

Za =Z score for alpha error chosen =1.96 at 5%level of significance Zb =Z score: 1.281 at 90% power

p1 = (proportion of hoarseness of voice in group 1); 80% p2 = (proportion of hoarseness of voice in group 2): 10% p = p1 + p2

After substituting the concerned values to above formula, we arrived at a sample size (n) >15 per group. However, 30 patients were enrolled in each group to increase the power of the study and exclude patients due to protocol violation. Hence sample sizes of 90 patients were selected for the study.

Inclusion criteria

Age between 18-60 years, Either sex male or female, ASA grading I, II posted for elective surgical procedures of duration more than two hours under general anaesthesia with endotracheal intubation

Exclusion criteria:

Age <18 or >60 years, Refused informed consent by patient, Patients undergoing emergency surgeries, Procedures requiring perioperative nasogastric tube placement, Patients with high risk of aspiration, Anticipated difficult airway, Pregnant women, Active upper respiratory tract infections, Preoperative sore throat, Previous history of GERD, Head and neck surgeries and surgeries requiring prone position, Patients requiring intubation attempts more than one, ASA Grade III/IV, Other systemic disorders of lung and patients with difficulty in communication.

METHODOLOGY

The study was done at our tertiary care centre in the department of Anesthesiology on all patients undergoing elective surgical procedures of duration more than two hours under general anaesthesia with endotracheal intubation attending OPD/IPD after due permission from the Institutional Ethics Committee and Review Board and after taking Written Informed Consent from the patients.

After approval from the Institutional Ethics Committee a valid informed consent was taken. Once the patients were enrolled for the study, a thorough history and physical examination was done as per proforma. An informed consent was taken in written from patients or patient’s attendant.

90 patients were divided into following three groups of 30 patients: Group A: ETT cuffs inflated with Air, Group B: ETT cuffs inflated with plain lignocaine (preservative free) and Group C: ETT cuffs inflated with alkalinized lignocaine Total 90 patients aged 18 60 years old (which were divided into 3 groups of 30 each) of either sex and ASA grading I/ II undergoing elective surgical procedures of duration more than two hours under general anaesthesia with endotracheal intubation.

Pre anaesthetic assessment

Thorough medical and surgical history of the patients, clinical evaluation and details of current medications were recorded of all the patients along with those satisfying the inclusion criteria were enrolled for study after taking written informed consent.

Preoperative Investigations

Haemoglobin, Bleeding time and Clotting time, Blood sugar level, Renal function tests, Liver function tests, ECG ( above 35 years) and Chest X-ray (above 35 years)

Routine physiological monitoring included non invasive arterial BP, Heart rate, Arterial oxy haemoglobin saturation Alkalinization of lignocaine was achieved by adding 2.5ml of 7.5% sodium bicarbonate to 2.5ml of 2% lignocaine with 5ml of saline (10ml). Alkalinization of lignocaine was checked with the use of universal indicator paper. All solution in GROUP C was ensured to have pH of above 7.

Intravenous access was secured and all the standard monitors attached with baseline vitals noted.

All the patients was preoxygenated for 3 mins and induction was done with iv Midazolam 0.03mg/kg, Fentanyl 1mcg/kg and iv Propofol 2mg/kg.

After ensuring bag and mask ventilation Inj Vecuronium 0.1mg/kg was given as muscle relaxant.

Patients were ventilated using bains circuit with either sevoflurane or isoflurane as inhalational agents.

Endotracheal intubation was done with appropriate sized polyvinyl chloride endotracheal tube as per gender after direct laryngoscopy.

The cuff was inflated till the air leak has just stopped which was assessed by auscultation. GROUP A cuff was inflated with air; GROUP B cuff was inflated with plain lignocaine and GROUP C cuff was inflated with alkalinized lignocaine.

The cuff pressure was measured in GROUP A with air soon after endotracheal cuff inflation and at interval of 1 hour, 2 hours and before deflation of cuff with the help of manometer.

After the procedure, inhaled anaesthetics were discontinued and patients were extubated after giving appropriate dosage of neuromuscular reversal agent.

Instruments used were Endotracheal tubes (Portex tubes) of appropriate sizes, Cuff inflating Syringe, Cuff manometer, Sphygmomanometer, NIBP, ECG monitor and Defibrillator and drugs for induction.

The following observations were recorded:

Haemodynamic responses to extubation –

Heart rate, systolic diastolic and mean blood pressure was measured immediately after giving reversal and after extubation T0 and subsequently at 5 mins T5, 10 mins T10, 15 mins T15, 30 mins T30, 60 mins T60.

Smoothness of extubation- Absence of coughing or bucking and variation less than 30% from baseline regarding heart rate, systolic, diastolic, and mean blood pressure is considered as smooth extubation.

Presence of sore throat, hoarseness of voice and cough were documented and graded at interval of two, four and six hours after shifting patients.

4 point graded scale was used for sore throat, hoarseness and cough.

Sore Throat: Grade 0: no hoarseness, Grade 1: mild discomfort or itchy sensation, Grade 2: pain on swallowing and Grade 3: pain at rest Hoarseness of Voice: Grade 0: no hoarseness, Grade 1: hoarseness noted only by patients, Grade 2: apparent hoarseness, mild and Grade 3: apparent hoarseness, severe

Cough: Grade 0: no cough, Grade 1: minimal cough, Grade 2: moderate cough and Grade 3: severe cough

Questionnaires on Patients' Satisfaction

1. Have you undergone any intubation procedures before ?
2. Do you feel any discomfort during present extubation ?
3. Do you have post procedure discomfort in the form of
4. Pain in throat (sore throat)?
5. Change in voice (hoarseness/dysphonia)?
6. Cough?
7. Pain while swallowing (dysphagia)?

Appropriate statistical software, including but not restricted to MS Excel, SPSS ver. 20 used for statistical analysis. Graphical representation done in MS Excel 2010.

A prospective, randomized, double blind study was undertaken for comparative evaluation of prevention of post intubation morbidity by inflating endotracheal cuff with air vs lignocaine vs alkalinized lignocaine. 90 patients were divided into following three groups of 30 patients:

Group A:   ETT cuffs inflated with Air

Group B:   ETT cuffs inflated with plain lignocaine (preservative free)

Group C:   ETT cuffs inflated with alkalinized lignocaine

The mean age of the patients in all the groups were comparable (41.33 ± 11.49 years vs. 40.13 ± 9.68 years vs. 40.67 ± 11.25 years).

Figure 1

Majority of the patients in Group A (63.3%), Group B (60%) and Group C (66.7%) were males while female patients constituted 36.7%, 40% and 33.3% of the study groups respectively. The ASA Grading of the patients between groups were comparable and statistically not significant. Mean BMI in all the groups were comparable (25.33 ± 3.85 kg/m2 vs. 25.71 ± 3.83 kg/m2 vs. 26.10± 3.61 kg/m2). Mean volume of agent instilled in the ETT cuff was comparable between the groups (5.93±1.31ml vs. 5.83±1.51ml vs. 6.07±1.26ml) and statistically not significant. The mean duration of surgery was comparable between the groups (237.53±38.48mins vs. 242.50±38.64mins vs. 240.60±36.23mins) and statistically not significant.

The cuff pressure was significantly high after intubation compared to before extubation in all the groups and the difference in cuff pressure between groups were statistically not significant. The incidence of bucking during extubation was significantly lower in Group C compared to Group A and Group B (30% vs. 26.7% vs. 3.3%).

              Figure 2

Heart rate values (HR) levels in Group A and Group B were significantly higher compared to Group C from at reversal till 15 minutes post extubation and from 30 minutes HR values in all 3 groups was comparable. Systolic blood pressure levels (SBP) levels in Group A and Group B were significantly higher compared to Group C from at reversal till 15 minutes post extubation and from 30 minutes SBP values in all 3 groups was comparable. Diastolic blood pressure (DBP) levels in Group A and Group B were significantly higher compared to Group C from at reversal till 15 minutes post extubation and from 30 minutes DBP values in all 3 groups was comparable. Mean arterial pressure (MAP) values in Group A and Group B were significantly higher compared to Group C from at reversal till 5 minutes post extubation and from 10 minutes MAP values in all 3 groups was comparable. SpO2 levels were comparable between the groups and statistically not significant. The incidence of smoothness of extubation was significantly higher in Group C compared to Group A and Group B (26.7% vs. 16.7% vs. 93.3%).

Figure 3

Sore throat grade was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B, 26 (86.7%) and 28 (93.3%) patients in Group C had Grade 0 at the end of 2 hours and 4 hours respectively. At 6 hours all three groups were comparable and there was no statistically significant difference. Hoarseness of voice grade was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B, 27 (90%) and 28 (93.3%) patients in Group C had Grade 0 at the end of 2 hours and 4 hours respectively. At 6 hours all three groups were comparable. Cough grade was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B, 28 (93.3%) and 29 (96.7%) patients in Group C had Grade 0 at the end of 2 hours and 4 hours respectively. At 6 hours all three groups were comparable with no statistically significant difference.

Figure 4

In the present study, majority of the patients (33.3%) patients in Group A were in the age group of 41-50 years followed by 51-60 years (26.7%), 18-30 years (23.3%) and 31-40 years (16.7%). Majority of the patients (33.3%) patients in Group B were in the age group of 41-50 years followed by 31-40 years (30%), 18-30 years (20%) and 51-60 years (16.7%). Majority of the patients (30%) patients in Group C were in the age group of 18-30 years followed by 51-60 years (26.7%), 41-50 years (23.3%) and 31-40 years (20%). The mean age of the  patients in all the groups were comparable (41.33 ± 11.49 years vs. 40.13± 9.68 years vs. 40.67 ± 11.25 years) and statistically not significant as per ANOVA test (p>0.05). Majority of the patients in Group A (63.3%), Group B (60%) and Group C (66.7%) were males while female patients constituted 36.7%, 40% and 33.3% of the study groups respectively. The difference between groups was statistically not significant as per Chi-square test (p>0.05). This is similar to the study of Podder S et al14 which showed mean age in all the groups were comparable (41.10±13.61, 38.67±13.43 and 38.20±13.47) years respectively.

In the present study, Group A had 24 patients (80%) with ASA grade I and 6 (20%) patients with ASA grade II, whereas Group B and C had 23 (76.7%) and 21 (70%) patients respectively with ASA grade I and 7 (23.3%) and 9 (30%) patients respectively with ASA grade II. The ASA Grading of the patients between groups were comparable and statistically not significant as per Chi-square test (p>0.05).

It was observed in the present study mean BMI in all the groups were comparable (25.33 ± 3.85 kg/m2 vs. 25.71 ± 3.83 kg/m2 vs. 26.10 ± 3.61 kg/m2) and statistically not significant and the mean volume of agent instilled in the ETT cuff was comparable between the groups (5.93±1.31ml vs.

5.83±1.51ml vs. 6.07±1.26ml) and statistically not significant with similar findings noted by Podder S et al14 and Gaur P et al.16

Mean duration of surgery in the present study was comparable between the groups (237.53±38.48mins vs. 242.50±38.64mins vs. 240.60±36.23mins) and statistically not significant.

In the present study, the cuff pressure was significantly high after intubation compared to before extubation in all the groups. Similar observations were noted by Podder S et al14, Gaur P et al16 and Rizvanović N et al17 in their studies.

Gaur P et al16 observed cuff pressure and volume achieved in the end of surgery were much higher in air group as compared to lignocaine group. Mean cuff pressures obtained at the end of surgery were 49.86 cm H2O and 19.66 cm H2O in A and L group respectively with a statistically significant difference between the two groups. Change in volume and pressure of cuff during surgery revealed significant difference in A group than group L.

Various factors contribute to the emergence of coughing and sore throat that may adversely affect the outcome if not monitored adequately. ETT cuff pressure is the indirect measure of pressure exerted by cuff over tracheal mucosa that is not monitored routinely.18

The critical function of ETT cuff is to provide adequate seal to airway during positive pressure ventilation to prevent aspiration due to under inflation. Long duration of cuff inflation can result in mucosal ischemia and further complications such as coughing. Endotracheal (ET) cuff pressures at approximately 30 cm H2O can impair tracheal mucosal perfusion, and a critical perfusion pressure is reached at 50 cm H2O which has been demonstrated by endoscopic studies.19 N2O anesthesia which is a common conjunct with other volatile anesthetics is the main factor, which increases the intracuff pressure by easily diffusing into the cuff with the advent of surgery.20

The effects of endotracheal tube cuff inflation media, air, saline and alkalinized 2% lidocaine on increase of cuff pressure (CP) found highest increase of mean CP was recorded in the group A (18.7±4.9), it was significantly lower (6.4±1.1) in the group S, while it remained stable in the group L (0.7±0.7).17

The incidence of bucking in the present study during extubation was significantly lower in Group C compared to Group A and Group B (30% vs. 26.7% vs. 3.3%). Podder S et al14 study with Bucking as assessed after giving of reversal agent showed Group C had a lower incidence of bucking compared to Group A and B and was clinically significant.

It was observed in the present study that the heart rate values (HR) levels in Group A and Group B were significantly higher compared to Group C from at reversal till 15 minutes post extubation. From 30 minutes HR values in all 3 groups was comparable and statistically not significant. Podder S et al14 study observed haemodynamic parameters (heart rate and mean arterial pressure) as measured at baseline before induction, at reversal and after extubation at 0, 5, 10, 15, 30 and 60 minutes after giving reversal. Group C had lower incidence of increase in heart rate compared to Group A and Group B which was statistically significant. From 30 minutes all 3 groups are comparable showing no difference.

In the present study mean arterial pressure (MAP) values in Group A and Group B were significantly higher compared to Group C from at reversal till 5 minutes post extubation and concordant findings were found by Podder S et al14 which showed Group C had lower incidence of increase in MAP compared to Group A and Group B. From 10 minutes all 3 groups are comparable showing no difference with Group A and Group B was comparable at all intervals. SpO2 levels were comparable between the groups and statistically not significant

The incidence of smoothness of extubation was significantly higher in Group C compared to Group A and Group B (26.7% vs. 16.7% vs. 93.3%) which is similar to the study done by Podder S et al14 which showed Group C had maximum smooth extubation compared to other two groups.

Sore throat grade in the present study was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B. Similar finding were noted by Podder S et al14 which showed sore throat grade was lowest in group C at the end of 2 hours and 4 hours, Soares SM et al21 found incidence of sore throat was 11 times higher in air group, (22) times higher in saline group compared to alkalinised lignocaine group (2%) and the decrease was maximum with 1% lignocaine, Babu RS et al22 observed efficacy of lignocaine 2% alone versus lignocaine 2% with dexamethasone on post- extubation emergence found no significant differences in the incidence of post-extubation sore throat, hoarseness of voice or laryngospasm and Malhotra S et al23 found use of saline or 2% lignocaine as a liquid media for filling the endotracheal tube cuff reduced postoperative sore throat and thereby tracheal morbidity.

Most of the surgical cases are managed with endotracheal intubation with Intermittent Positive Pressure Ventilation (IPPV).  Post-intubation, the endotracheal cuff is generally inflated with air which prevents aspiration of gastric contents. Postoperative sore throat, hoarseness of voice and cough are the side effects of intubation. These problems contribute to patient discomfort and laryngotracheal morbidity and delays discharge. The haemodynamic response seen during extubation can lead to significant morbidity and can be catastrophic in cardiopulmonary compromised patients. Smooth extubation with a comfortable post-operative recovery is the desired goal.

The hoarseness of voice grade was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B and 27 (90%) and 28 (93.3%) patients in Group C had Grade 0 at the end of 2 hours and 4 hours respectively. At 6 hours all three groups were comparable and there was no statistically significant difference. Podder S et al14 found hoarseness of voice at 2 hours and 4 hours was lowest in group C, Jolly S et al24 showed that hoarseness of voice at post-extubation (24hrs) was minimal in alkalinised lignocaine group (6%) when compared to saline (19%) and plain lignocaine (11%) respectively, Sumathi PA et al25 reported widespread application of betamethasone gel on the tracheal tube decreased the incidence and severity of postoperative sore throat, cough and hoarseness of voice. and Estebe JP et al15 stated that alkalinized intracuff lignocaine improves cuff tolerance; however, the local anesthetic effect does not depress the swallowing reflex so that the patient can protect the airway.

Cough grade in the present study was significantly lower in Group C at the end of 2 hours and 4 hours compared to Group A and Group B and 28 (93.3%) and 29 (96.7%) patients in Group C had Grade 0 at the end of 2 hours and 4 hours respectively. At 6 hours all three groups were comparable which is similar to the studies of Podder S et al14 which observed cough was lowest in group C at the end of 2 hours and 4 hours, Gaur P et al16 reported Incidence of coughing and POST at immediately, 1h and 24h postoperatively was significantly higher in air group compared to lignocaine group., Rizvanović N et al17 found lowest incidence of PTMI was in the group L and Yang SS et al26 systematic review and meta-analysis observed administration of i.v. lidocaine compared with placebo or no treatment led to large reductions in post-extubation cough and in postoperative sore throat at 1h.

It is well known that the irritant receptors present in tracheal mucosa are very sensitive to physical or chemical stimulation. ETT cuff is made of polyvinylchloride, which forms a semi-permeable membrane through which lipophilic substance can diffuse across. Lignocaine thus reaching the tracheal mucosa has perhaps anaesthetised the mucous membrane cushioning the extubation response and thus decreasing the immediate postoperative morbidity. Alkalinized Lignocaine when used as an intracuff liquid has preventive effects on cough incidence owing to its effect on suppressing mechanical and chemical-induced airway reflexes, which includes cough reflex.

ETT cuffs inflated with alkalinized lignocaine is very effective in reducing the laryngotracheal morbidity like sore throat, hoarseness of voice and cough in the immediate postoperative period when compared to saline and air. It also helps in smoother extubation by decreasing haemodynamic response and bucking over the tube.

Alkalinized lignocaine provides an improved protective effect in preventing postoperative laryngotracheal morbidity in form of coughing.

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