JOURNAL OF MEDICAL

COLLEGES OF PLA

www.elsevier.com/locate/jmcpla

Journal of Medical Colleges of PLA 28 (2013) 302-312

Improving endotracheal tube tolerance with intracufflidocaine: a

meta-analysis of randomized controlled trials

CHEN Wei△, SUN Pengling

△, YANG Liye, PU Jun, YUAN Hongbin, TIAN Mouli

*

Department of Anesthesiology, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China

Received June 01, 2013; accepted September 08, 2013

Abstract

Objective: The aim of this study was to compare the efficacy in alleviating the endotracheal tube related discomfort and the

safetyof intracufflidocaine (in different forms) with air and/or normal saline (NS) during general anesthesia with tracheal intubation.

Methods: Cochrane Central Register of Controlled Trials, PubMed and Embase were searched for relevant studies. Thirteen

randomized, controlled trials involving 1 010 patients were ultimately identified. A meta-analysis of all randomized controlled trials

fulfilling the predefined criteria was performed. Random-effect model and subgroup studies were used when significant heterogeneity

existed among those trials. Results: Compared with air and NS, intracufflidocaine could significantly alleviate the severity of sore

throat at different time points (15min, 30min, 1h, 2h, 3h, 6h, 12h and 24h after extubation) and the occurrence of cough, restlessness,

postoperative nausea and vomiting, dysphonia and hoarseness. Besides intracufflidocaine brought about a significant prolongation of

spontaneous ventilation time. It was worth mentioning that, compared withlidocaine or its hydrochloride form, alkalinized

lidocainewas much more efficient in reducing the severity of sore throat and prolonging spontaneous ventilation time. Conclusion: The

present meta-analysis indicates that intracufflidocaine can significantly improve endotracheal tube tolerance and this improvement can

be strengthened by alkalinization of lidocaine.

Keywords: Intubation intratracheal; Lidocaine administration; Anesthesia recovery period

△The authors contributed equally to this work.

*Corresponding author.

E-mail address: tianml@aliyun.com (TIAN M.)

CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312 303

1.Introduction

In the management of patients during anesthesia

or in the intensive care unit, endotracheal tube (ETT)

is widely used as a ventilatory device. However, it

could induce some discomfort, such as coughing, sore

throat, laryngospasm, hypertension and increased

intracranial and intraocular pressures. Among them,

postoperative sore throat is the most common

complaint after tracheal intubation, with the

occurrenceup to 90% [1]. To reduce the complications

and improve ETT tolerance, preventing of the

expansion of air in an endotracheal tube cuff (ETTC)

is suggested [2].

Filling the cuff with saline[3] or lidocaine [4-5]

has been used to avoidoverexpansion of the cuff.Large

doses of lidocaine are needed,because only a very

small amount of lidocainecan diffuse through the ETT

cuff [6]. Once the cuff ruptures, the patient may in face

a dangerous situation caused of over dose absorption

of lidocaine vascular. Thus, the addition of sodium

bicarbonate (NaHCO3) (i.e., alkalinization) to a small

dose of lidocaine, increasing the diffusion of lidocaine

through the ETT cuff, has been recommended [7].

Many clinical randomized controlled trials (RCTs)

have been undertaken to investigate the efficacy and

safety of filling in ETTC with lidocaine[4,7-21]. Since

control groups (air or NS), formations of lidocaine

(alkalinized or hydrochloride), time for evaluating the

efficacy after extubation and sample sizes were quite

different from each other, consensus could’t be

achieved easily. Therefore, we carried out a

meta-analysis of all relevant RCTs to evaluate the

efficacy and safety of introcufflidocaine.

2. Methods

All RCTs carried out to assess the effectiveness

and safety associated with the use of intracufflidocaine

compared with air or NS were identified and included

in our research.

2.1. Search strategy

The Cochrane Central Register of Controlled

Trials (Cochrane Library issue 3, 2009), PubMed (up

to August, 2009), Embase (1980 to August, 2009) and

Chinese Biomedical Database (SinoMed, 1979 to

August 2009) were searched. The search combined the

terms of lidocaine and its trade names in different

forms (dolicaine, LID, LIDD, lidocaine, lignocaine,

lydocaine, XYL, xylocaine), and also involved

different forms of the terms of endotracheal tube

(endotracheal catheter, tracheal catheter) and cuff. We

also investigated the reference lists of original reports

and reviews to identify those eligible RCTs that had

not been involved in the computerized databases.

Literature search was performed without language

restriction.

2.2.Trials selection

All trials that conformed to the following

standards were included in this study: 1. RCTs;

2.patients with the implementation of general

anesthesia, tracheal intubation; 3. ETTC was filled

with lidocaine while it could be filled in various ways

(prefilled 90min before intubation or filled after

intubation), in various concentrations and in various

304 CHEN Wei et al. / Journal of Medical Colleges of PLA 28(2013) 302-312

forms (alkalinized or hydrochloride); 4. the control

group was filled with air or NS. Articles in other ways,

such as intravenous or topical lidocaine were

simultaneously used in control group to reduce the

occurrence of emergence phenomena were excluded

in this study.

Trial eligibility was determined by two authors

(CW, SPL) independently, and any disagreement was

resolved by discussion. All eligible trials were checked

by TML and YHB.

2.3. Outcome measures

The primary efficacy variable used in our

research was the incidence and severity of sore throat

which were graded at different time after extubation

with a pain scale (visual analog scale, VAS) from 0 (no

pain) to 100 (worst pain imaginable). The incidence of

cough, restlessness, postoperative nausea and vomiting

(PONV), dysphonia, hoarseness and time of

spontaneous ventilation time (time between

emergence of spontaneous breathing and extubation)

were also included in our research as the secondary

efficacy variables to evaluate ETT tolerance. The

occurrence of restlessness was checked before

extubation.

2.4.Data extraction

Data were extracted by two authors (CW, SPL)

independently, and any dissension was tackled through

discussion. The following data were included in a

predesigned electric review form: the authors of each

study, the year of publication, the design of the trial,

the number, of the patients, age and gender distribution,

anesthesia time, the maintenance of anesthesia with or

without N2O, plasma lidocaine concentrations, the

incidence and severity of sore throat, the incidence of

cough, PONV, dysphonia, hoarseness and time of

spontaneous ventilation time after extubation. And the

occurrence of restlessness before extubation was

included. Engauge Digitizer 4.1 was used to extract

data when it was displayed graphically. Moreover, we

recorded the proportion of withdrawals, number of

patients reporting adverse events and number of

patients with rupture of the ETTC during anesthesia.

2.5. Qualitative assessment

Two authors (CW and SPL) appraised the studies

independently. Trials were rated for methodological

quality using the scoring system developed by Jadad

and properly adjusted [22]. The quality scoring system

was as following: 1.The method of generating random

sequence: the sequence was generated through

computer-generated random sequence, random

number table, and so on; random sequence was

mentioned, but the method to generate random

sequence was not confessed; semi-random or

quasi-randomized trial, only using alternate methods

to distribute the cases, such as the order of admission,

single or double of the birth date number; 2. double-

blind method: the specific methods of implementation

of double-blind was described, and was considered

appropriate; study only referred to the use of

double-blind method; the use of double-blind trial was

referred to, but the methods were not appropriate;

3. withdrawals and dropouts: the details of the number

of cases missing from the groups were described;

withdrawals and dropouts were not referred to. The

CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312 305

highest score was 5 and the trials which got a score of

more than 3 were considered of high quality.

2.6. Statistical analysis

Since not all the outcomes were reported in each

article, we took meta-analysis for each comparison

separately. We used a random-effect model to combine

the data if significant heterogeneity existed according

to P-value (P< 0.1).

We calculated Risk Ratio (RR) for dichotomous

outcomes (Mantel-Haenszel Method) and weighted

mean difference (WMD) for continuous ones

(standardized mean difference (SMD) was used when

trials using different scales). The statistical analysis

was carried out using Review Manager Version 5.0.23

(Cochrane Collaboration, Oxford, UK).

3. Results

Seventeen relevant studies associated with

intracufflidocaine in preventing cough and sore throat

after extubation during general anesthesia were

identified through the literature search [4-5,7-21].

Among them, 4 articles [5,11,19-20] were excluded

and 13 RCTs were included in the present

meta-analysis. The flow of the studies included in our

analysis was shown in Fig.1. Most of these RCTs

included were in English, only onein Spanish.

All included studies were prospective RCTs,

involving 1010 patients. Among them, there were 2

trials scored 5; 8 trials scored 4 and 3 trials scored 3.

Characteristics of the included trials were shown in

Table 1.

Fig 1. Inclusion and exclusion criteria of this meta-analysis

3.1. Efficacy

Efficacy analysis was performed to evaluate the

improvement of endotracheal tube tolerance with

intracufflidocaine on the analysis of the severity of

sore throat, the incidence of sore throat, cough,

restlessness, PONV, dysphonia and hoarseness before

or after extubation. And spontaneous ventilation time

also contributes to the conclusion of efficacy.

3.1.1. Incidence of sore throat after extubation

3.1.1.1. Lidocaine versus air

Totally 2 trials [4, 10] reported the incidence of

sore throat after extubation when intracufflidocaine

was compared with air. There was no significant

difference at 1h after extubation (RR, 0.34, 95%

Confidence Interval (95% CI) 0.09 to 1.24, random

effect model) while difference was found at 24h after

extubation (RR, 0.47, 95% CI 0.30 to 0.74, fixed

effect model). (Table 2)

306 CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312

Table 1.

Characteristics of randomized controlled trials included in the meta-analysis.

Trials Number Sex

(M/F)

Maintenance of

anesthesia

Mean surgical time

(h) Treatment Control Quality Grade

Soltani et al 204 118/86 N2O/O2 <1 Lidocaine Air 4

Navarro et al 106 88/18 N2O/O2 >1 Lidocaine Air 4

Altinas et al 70 31/39 N2O/O2 >1 Lidocaine NS 3

Bajaj et al 80 NR N2O/O2 NR Lidocaine NS-air 4

Dollo et al 15 15/0 N2O/O2 >1 Lidocaine Air 3

Estebe et al 60 39/21 N2O/O2 >1 Lidocaine Air 4

Estebe et al 75 40/35 N2O/O2 >1 Lidocaine Air 4

Estebe et al 60 13/47 Air /O2 <1 Lidocaine Air 5

Fagan et al 57 NR N2O/O2 >1 Lidocaine NS-air 3

Huang et al 80 42/38 N2O/O2 >2 Lidocaine NS 4

Navarro et al 50 NR N2O/O2 >1 Lidocaine Air 4

Porter et al 75 NR N2O/O2 or O2 <1 Lidocaine NS-air 4

Zamora Lozano et al 78 38/40 NR >1 Lidocaine Air 5

NR: Not Reported; NS: Normal Saline

Table 2.

Incidence of sore throat, restlessness, PONV, dysphonia, hoarseness and spontaneous ventilation time, intracuff lidocaine vs air.

Sore throat

Restlessness

PONV Dysphonia Hoarseness

Spontaneous ventilation time

RR 95% CI* RR 95% CI* RR 95% CI*

RR 95% CI* RR 95% CI*

WMD 95% CI※

0.34†＃

[0.09,1.24] 0.10

‡ [0.02,0.39] 0.29

‡ [0.15,0.57] 0.13

‡ [0.03,0.53] 0.29

† [0.10,0.82] 16.84

† [8.20,25.47]

0.47‡＆

[0.30,0.74]

RR: Risk Ratio; 95% CI: 95% Confidence Interval; PONV: Postoperative nausea and vomiting; WMD: Weighted mean difference; †: Random effect

model; ‡:Fixed effect model;

*: No significant difference exists when 1 is included;

※: No significant difference exists when 0 is included;

＃:1 h after

extubation; ＆

:24 h after extubation

3.1.1.2. Lidocaine versus saline

Totally 4 trials [8-10,16] reported the incidence

of sore throat after extubation when

intracufflidocaine was compared with saline. There

was no significant difference at 1h after extubation

(RR, 0.43, 95% CI 0.16 to 1.16, random effect

model) while difference was found at 24h after

extubation (RR, 0.18, 95% CI 0.07 to 0.46, fixed

effect model).

3.1.2. Severity of sore throat

There were 4 trials[7, 12-14] reporting the

severity of sore throat after extubation when

CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312 307

alkalinized lidocaine (lidocaine with addition of

sodium bicarbonate) was used compared with air.

Data at different time points were divided into

subgroups and combined. At each time alkalinized

lidocaine reduced the severity of sore throat.

The results are as follows: at each time (15min

(WMD, -25.95, 95% CI -36.39 to -15.52), 1h

(WMD, -18.96, 95% CI -28.22 to -9.69), 2h

(WMD, -19.40, 95% CI -25.46 to -13.34), 3h

(WMD, -18.71, 95% CI -22.32 to 15.10), 24h

(WMD, -13.24, 95% CI -16.86 to -9.61)) after

extubation alkalinized lidocaine reduced the

severity of sore throat significantly (in random

effect model). (Fig. 2)

Fig 2. Severity of sore throat at different time points after extubation of alkalinized lidocation vs air.

308 CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312

There were 2 trials reporting the severity of

sore throat after extubation comparing alkalinized

lidocaine with lidocaine [7,12].

The results are as follows: at each time (15 min

(WMD, -12.27, 95% CI -18.86 to -5.68), 2 h

(WMD, -16.00, 95% CI -21.26 to -10.74)) after

extubation alkalinized lidocaine reduced the

severity of sore throat significantly (in fixed effect

model). (Table 3)

Table 3.

Severity of sore throat and spontaneous ventilation time of alkalinized lidocaine vs lidocaine alkalinized lidocaine vs lidocaine.

Interventions Severity of sore throat Spontaneous ventilation time

WMD 95% CI* WMD 95% CI*

-12.27‡＃ [-18.86,-5.68]

13.35‡ [8.22,18.47] -16.00‡＆ [-21.26,-10.74]

WMD: Weighted Mean Difference; 95% CI: 95% confidence interval; †: Random effect model;

‡: Fixed effect model;

*:No significant difference exists

when 0 is included; #

:15m after extubation; ＆

:2h after extubation

3.1.3. Incidence of cough after extubation

There were 4 trials [10,15,18,21] reporting the

incidence of cough at 1h after extubation comparing

lidocaine with air or saline. Differences were found

both when lidocaine versus air (RR, 0.32, 95% CI

0.19 to 0.53, fixed effect model) and when lidocaine

versus saline (RR, 0.50, 95% CI 0.28 to 0.90, fixed

effect model). (Fig. 3)

Fig.3. Incidence of cough at 1h after extubation of lidocaine vs air/saline.

CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312 309

3.1.4. Spontaneous ventilation time

Totally 4 trials [7, 12-14] reported the time of

spontaneous ventilation time when alkalinized

lidocaine was compared with air. Alkalinized lidocaine

prolonged spontaneous ventilation time significantly

compared with air (WMD, 16.84, 95% CI 8.20 to

25.47, random effect model). (Table 2)

Totally 2 trials [7,12] reported spontaneous

ventilation time when alkalinized lidocainewas

compared with lidocaine. Alkalinized lidocaine

prolonged spontaneous ventilation time significantly

compared with lidocaine (WMD, 13.35, 95% CI 8.22

to 18.47, fixed effect model). (Table 3)

3.1.5. Incidence of restlessness before extubation

Significant difference existed (RR, 0.10, 95% CI

0.02 to 0.39, fixed effect model) when alkalinized

lidocaine compared with air according to 3 trials

[7,13-14] reporting the incidence of restlessness before

extubation. (Table 2)

3.1.6. Incidence of PONV

Significant difference existed (RR, 0.29, 95% CI

0.15 to 0.57, fixed effect model) when alkalinized

lidocaine compared with air according to 3 trials

[7,13-14] reporting the incidence of PONV. (Table 2)

3.1.7. Incidence of dysphonia

Significant difference existed (RR, 0.13, 95% CI

0.03 to 0.53, fixed effect model) when alkalinized

lidocaine compared with air according to 3 trials

[7,13-14] reporting the incidence of dysphonia.

(Table 2)

3.1.8. Incidence of hoarseness

Significant difference existed (RR, 0.29, 95% CI

0.10 to 0.82, random effect model) when alkalinized

lidocaine compared with air according to 4 trials

[7,13-14, 17] reporting the incidence of hoarseness.

(Table 2)

3.2. Safety

Although each article included mentioned that

once the cuff was ruptured, lidocaine would be

absorbed quickly, thus causing a serious toxic reaction,

none of the studies reported such an adverse effect.

Plasma concentration of lidocaine was monitored in 3

[9,13,17] of all the 13 trials, and toxic concentration of

plasma was not reached in any patient. In spite of this,

the safety of intracufflidocaine should be concerned

because the toxic reactions caused by lidocaine would

be serious.

4. Discussion

Most of the patients undergoing general

anesthesia require endotracheal intubation to construct

an airway torealize positive pressure ventilation, so to

provide optimal conditions for surgery. Possible

causes of postoperative complications are intubation

trauma, mucosal dehydration or edema, pharyngeal

310 CHEN Wei et al. / Journal of Medical Colleges of PLA 28(2013) 302-312

airways, and succinycholine [23]. The supposed

mechanism for coughing and sore throat after

extubation is the stimuli in the trachea caused by the

tube and its cuff. Tracheal ischemia caused by

excessive pressure may also be responsible for these

complications [24].

At present, many studies concerning the

application of intracufflidocaine to improve ETT

tolerance after extubation have been undertaken.

However, the usage of intracufflidocaine is in various

ways (prefilled 90min before intubation or filled after

intubation), in various concentrations (1%，2%，4%，

10% lidocaine hydrochloride) and in various PH

values (in alkalinized or hydrochloride formation). In

this meta-analysis we reviewed 13 RCTs, the results

showed that intracufflidocine reduced the severity of

sore throat, the incidence of cough, restlessness

(before extubation), PONV, dysphonia and hoarseness,

meanwhile,it prolonged spontaneous ventilation time.

This revealed that intracufflidocaine provided superior

ETT tolerance compared with air or NS.

This effect may bedue to the decrease of the cuff

pressure, and lidocaine inserted into the ETTC might

cause anesthesia of the trachea by diffusing across the

cuff membrane [15]. Besides, different formation can

impact the efficacy of intracufflidocaine. Our

meta-analysis showed that alkalinized lidocaine had a

better effect in reducing the severity of sore throat and

prolonging spontaneous ventilation time than lidocaine

or lidocaine hydrochloride. This was consistent with

individual trials that alkalinization of

intracufflidocaine might be more effective and safer

for the alkalinized lidocaine could penetrate the cuff

membrane more easily according to previous in vitro

release studies [12].

Strengths of this meta-analysis were: 1) the

studies we included were of high quality. All studies

included in this meta-analysis were 3-5 scores

qualified with adjusted Jadad scoring system; 2) we

performed a comprehensive search without language

restrictions; 3) a comprehensive analysis was carried

out, including subgroup analysis to make the

conclusion reliable; 4) among all the 13 studies

included in this review, the outcomes of 12 studies

consistently showed that lidocaine could reduce the

incidence of complications and the severity of sore

throat after extubation. Only 1 study included with

negative result [18].

Limitations of this review should be considered.

While all ETTC were filled with lidocaine in this study,

the concentrations were not exactly the same. Besides,

we didn’t take the characteristics of patients and

surgeries into consideration. All these factors can

produce heterogeneity which is frequent for a

meta-analysis.

In conclusion, this meta-analysis shows that

intracufflidocain can significantly reduce the severity

of sore throat, the incidence of cough, restlessness

(before extubation), PONV, dysphonia, hoarseness and

prolong spontaneous ventilation time, thus can provide

superior ETT tolerance compared with air or NS. And

this efficacy can be strengthened by alkalinization of

lidocaine.

Acknowledgements

Thank Zamora for his providing the original

article and unpublished data.

CHEN Wei et al./ Journal of Medical Colleges of PLA 28(2013)302-312 311

Conflict of Interest

All the authors declared no potential conflict of

interest.

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