Acta Anaesthesiol Scand 2000; 44: 511–516 Copyright C Acta Anaesthesiol Scand 2000Printed in Denmark. All rights reserved

ACTA ANAESTHESIOLOGICA SCANDINAVICA

ISSN 0001-5172

Local anaesthesia for awake fibreoptic nasotrachealintubation

P. KUNDRA, S. KUTRALAM and M. RAVISHANKAR

Department of Anaesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India

Background: Awake fibreoptic nasotracheal intubation (FNI) isperformed in potentially difficult airways under local anaes-thesia. This observer-blinded study was designed to evaluatethe efficacy of upper airway anaesthesia produced by nebulizedlignocaine against combined regional block (CRB) for awakeFNI.Methods: Forty-eight ASA 1 adults were randomly allocated toreceive 4 ml of 4%-nebulized lignocaine (nebulization group) ortranslaryngeal block, bilateral superior laryngeal nerve blockand three 4% lignocaine-soaked cotton swabs in the nose (CRBgroup). Facial grimace and patient comfort were assessed bygrimace and airway reactivity scores. Patients reported their dis-comfort on a 4-point score.Results: All patients underwent successful FNI without signifi-cant discomfort; 79% in the nebulization group and 83% of thepatients in the CRB group reported the procedure to be comfort-able. A higher grimace score was recorded on insertion of theendotracheal tube (ETT) through the nostril in the nebulizationgroup when compared to the CRB group, P,0.005. Similarly,

TRACHEAL intubation with a flexible fibreoptic lar-yngoscope (FOL) provides good intubation con-

ditions under visual control in patients with a difficultairway (1). Whenever difficulty in intubation is antici-pated, tracheal intubation with the patient awake isoften the safest option (2). However, effective topicalanaesthesia of the upper airway is mandatory for pa-tient comfort and subsequent successful instrumen-tation (1). Fibreoptic intubation in awake subjects canbe facilitated by combining intravenous sedation withtopical application of local anaesthetic and nerveblocks. The latter often includes a superior laryngealnerve block (SLNB) as well as translaryngeal injectionof local anaesthetic (3). Bigeleisen et al. (3) demon-strated that addition of translaryngeal injection to top-ical anaesthesia of the nose and SLNB produced excel-lent intubating conditions with minimal coughing epi-sodes in patients undergoing awake fibreopticnasotracheal intubation (FNI). Combined regionalblocks involving multiple needle pricks might en-hance apprehension in the patient and reduce co-op-

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patients in the CRB group were more comfortable during pas-sage of the ETT into the glottis, as compared to the nebulizationgroup. A progressive increase in heart rate was observed in allpatients from the beginning of the procedure, but the rise in thenebulization group was greater, (P,0.05) and also lasted longerthan in the CRB group (P,0.05). Mean arterial pressure washigher in the nebulization group when compared to the CRBgroup (P,0.05), with patients belonging to the CRB group dem-onstrating considerable haemodynamic stability.Conclusions: Both nebulization and CRB produced satisfactoryanaesthesia of the upper airway, but CRB provided better pa-tient comfort and haemodynamic stability.

Received 4 March, accepted for publication 6 December 1999

Key words: Intubation: tracheal; equipment: fiberoptic laryngo-scope; anesthetics, local: lignocaine.

c Acta Anaesthesiologica Scandinavica 44 (2000)

eration. Nebulization of the local anaesthetic offers anattractive alternative.

Topical anaesthesia of the entire airway can be suc-cessfully achieved by aerosolized local anaesthetic. Itis safe, effective and has good patient acceptability (4).However, the evidence in favour of either nebuliz-ation or combined regional blocks is as yet inconclus-ive. This study was designed to evaluate the efficacyof nebulization against combined regional blocks foranaesthesia of the upper airway in patients under-going awake FNI.

Methods

The study was conducted in 48 ASA 1 adults withpotentially difficult airway scheduled to undergo elec-tive surgery under general anaesthesia. Potential dif-ficult airways included significant temporomandib-ular joint dysfunction and restricted neck movements.The institutional ethics committee approved thestudy. During the preoperative visit, the details of

P. Kundra et al.

awake FNI were explained and informed consent wasobtained from each patient.

Patients were premedicated with 10 mg of di-azepam orally, 0.15 mg/kg of morphine and 0.2 mgof glycopyrrolate intramuscularly 90 min beforesurgery. In addition, 2–3 drops of 0.05% xylometazo-line were instilled in each nostril. In the operatingroom, an intravenous cannula was sited and a L&TMinimon, non-invasive blood pressure monitor withelectrocardiogram was programmed to record thetime and mean blood pressure (MAP) every minute,while the Ohmeda 5250 Respiratory Gas Monitor wasused for continuous monitoring of haemoglobin satu-ration (SpO2) and heart rate (HR). A 5-min stabiliza-tion period was allowed before baseline (control)measurements were made. After recording the base-line HR, SpO2, and MAP for 2 min, sedation was pro-duced with incremental doses of diazepam (2.5 mg)intravenously. Sedation was considered adequatewhen the patient was calm, without apprehensionand fell asleep if undisturbed, but was able to followverbal commands. The total dose of diazepam wasnoted. The study was observer blinded where patientswere randomly assigned (closed envelope technique)to receive either nebulized 4% lignocaine (nebuliz-ation group) or the combined regional blocks, (CRB)i.e. topical anaesthesia of nasal mucosa, bilateralSLNB and translaryngeal block (TLB) for anaesthesiaof the upper airway (CRB group).

In group 1 (nebulization group, nΩ24), topical an-aesthesia was accomplished using a Hudson’s smallvolume nebulizer filled with 4 ml of 4% lignocaine,driven by a flow of 8 l of oxygen per minute. Thenebulizer was connected via a 25-cm corrugated tub-ing to the disposable nebulizer facemask strappedover the patient’s nose and mouth. The patients wereinstructed to breathe through their nose. The total vol-ume took about 10 min to be nebulized. These pa-tients also had 3 placebo-soaked cotton swabs placedin the nostril while the sites of SLNB and TLB wereobscured by an adhesive tape in both groups.

In patients in group 2 (CRB, nΩ24), anaesthesia ofthe nasal mucosa was achieved by application of 3cotton swabs soaked in 4% lignocaine solution. Thecotton swabs were introduced into the selected nos-tril, one at a depth of 1.5 cm superiorly (to block thebranches of ethmoidal nerves), and two at a depth of2–2.5 cm (to block the sphenopalatine ganglion andbranches of the maxillary division of the trigeminalnerve). The swabs were kept in place for 3 min. Su-perior laryngeal nerve blocks were performed by theexternal approach bilaterally with 2–3 ml of 2% ligno-caine after a negative aspiration test. A translaryngeal

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blockade was achieved by injection of 2 ml of 4%lignocaine via a 22-gauge intravenous cannula in-serted through the cricothyroid membrane. In ad-dition, the patients received nebulized placebo.

An endotracheal tube (ETT) of appropriate sizesoftened in warm water and selected individually ac-cording to the size of the nostril was mounted on theFOL. Five minutes after administration of the local an-aesthetic, the FOL (LF-1; Olympus Optical, Tokyo, Ja-pan) was lubricated with water-soluble ointment andintroduced through the selected nostril into the oro-pharynx. Oxygen 2 l/min was delivered through theworking channel of the FOL for oxygenation and pre-vention of mucosal webbing of the tip of the instru-ment. After identifying the epiglottis and the vocalcords, the FOL was manoeuvered across the vocalcords into the trachea. The ETT was threaded over itinto the trachea, 2–3 cm above the carina. The cuffwas inflated and the FOL was withdrawn. Then sleepwas induced with thiopentone.

An independent observer, blinded to the group as-signment, assessed the facial grimace of the patient bya grimace score (0Ωno grimace: no change in the facialexpression; 1Ωminimal grimace: a single change inthe facial expression; 2Ωmild grimace: grimacing fa-cial expressions; 3Ωmoderate grimace: severe facialgrimace but without reflex head movements; 4Ωse-vere grimace: severe facial grimace associated withdiscomforting head movements; 5Ωvery severe grim-ace: severe facial grimace associated with protectivehead and limb movements). The facial grimace scorewas recorded during introduction of the FOL and thepassage of the ETT into the nostril. Laryngeal anaes-thesia was separately assessed by evaluating patientcomfort on an airway reactivity score with 0Ωno reac-tivity, 1Ωone cough or gag only, 2Ωmore than onecough or gag but acceptable conditions and 3Ωunac-ceptable conditions. Airway reactivity scores werenoted on passage of FOL and ETT into the trachea.HR, MAP and SpO2 were recorded every minute until2 min after tracheal intubation.

Data were collected, as follows: 1) Control record-ings before sedation. 2) 2 min after sedation with di-azepam. 3) At the beginning of the fibrescopy. 4) Afterentry of the FOL in the trachea. 5) After advancing theETT through the nasopharynx. 6) Immediately aftertracheal intubation. 7) 1 min and 2 min after trachealintubation. The time from insertion of the FOL, to thecompletion of intubation (intubation time) was meas-ured. Supplementary local anaesthesia was providedwith 1% lignocaine injected through the FOL if patientdiscomfort was hindering the procedure. The totaldose of lignocaine utilized was noted for each patient

Local anaesthesia for fibreoptic intubation

Table 1

Patient characteristics.

NEB group CRB groupVariable (nΩ24) (nΩ24)

Age (yr) 36∫13.8 37∫13.7Weight (kg) 51.1∫12 51.2∫10.5Intubation time (min) 5.1∫1.2 4.5∫1.3EtCO2 (mm Hg) 38.9∫4 38.6∫3.1Diazepam (mg) 0.8∫0.8 0.5∫0.6

Values expressed as: mean∫SD; EtCO2ΩEnd-tidal carbon dioxide;NEB groupΩNebulization group; CRB groupΩCombined regionalblock group.

and never exceeded 5 mg/kg. If supplementary localanaesthetic did not lessen the patient’s discomfort, theprocedure was abandoned followed by induction ofgeneral anaesthesia.

The day after surgery the patients were asked toselect from a graded scale the degree of discomfortthey remembered during the awake intubation pro-cedure. The scale they were shown consisted of 0Ωnodiscomfort, 1Ωminimal discomfort, 2Ωuncomfortableand 3Ωextremely uncomfortable.

The data were collected and analysed using SPSSversion 6.0 statistical software. Demographic and clin-ical data from the two groups were compared usingtwo tailed t-tests. Intergroup differences among thehaemodynamic variables recorded over time wereanalysed by using a two-way repeated measure analy-sis of variance, with group as the independent samplefactor and time as the repeated-measurement factor.A significant group by time interaction was followedby tests of significance using Tukey’s method to com-pare the two groups at various points in time. Grim-ace scores and airway reactivity scores were analysedby Mann-Whitney U test. The data obtained from thepatient assessment scale and the incidence of nasalbleed were assessed by using the chi-square test. A Pvalue of ,0.05 was considered statistically significantfor all tests.

Results

The groups were comparable with regard to age,weight and basal cardiovascular parameters. Theamounts of diazepam given to produce sedation weresimilar in the two groups; 8/24 patients received in-crements of diazepam in the nebulization group com-pared to 5/24 in the CRB group. There was no differ-ence in intubation time or end-tidal carbon dioxidelevel immediately after intubation between thegroups (Table 1).

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Grimace scores recorded at the insertion of the FOLinto the nostril were not significantly different be-tween the two groups. However, significantly highergrimace scores were recorded on insertion of the ETTthrough the nostril in the nebulization group (median4.5, range 3–5), when compared to the CRB group(median 3, range 2–5); P,0.005. Median airway reac-tivity score on passage of the FOL through the glottiswas similar in both groups. Five patients in the CRBgroup and 7 patients in the nebulization group (PΩ0.05) needed supplemental doses of lignocainethrough the FOL. Airway reactivity scores were

Fig. 1. Heart rate and mean arterial pressure over time(mean∫SD). - - - P - - - Nebulization Group, nΩ24. — H — Com-bined Regional Block Group, nΩ24. PreopΩPreoperative, FOBΩFibreoptic Laryngoscope, ETTΩEndotracheal tube, INTΩIntubation.* P,0.05ΩNebulization group versus Combined regional block group;** P,0.005ΩNebulization group versus Combined regional blockgroup; π P,0.05ΩChange within Nebulization group as compared tothe preoperative value; . P,0.05ΩChange within Combined regionalblock group as compared to the preoperative value.

P. Kundra et al.

higher during endotracheal intubation in the nebuliz-ation group when compared to the CRB group (me-dian values 3 and 1, respectively); P,0.005.

HR increased more at all time points in the nebuliz-ation group, when compared to the CRB group. Sig-nificantly higher HR were recorded from the insertionof the FOL into the glottis till 2 min after ac-complishing endotracheal intubation (P,0.05, Fig. 1)in the nebulization group when compared to the CRBgroup. The mean maximal rise in HR from the pre-operative value was 22 beats/min in the nebulizationgroup and 9 beats/min in the CRB group. In bothgroups, the peak rise in HR corresponded to the timeof endotracheal intubation. The increase in HR lastedtill the ETT was passed into the glottis in the CRBgroup while it lasted till the end of 1 min afterendotracheal intubation in the nebulization group(Fig. 1).

MAP rose significantly from the time of insertion ofthe FOL into the glottis till the endotracheal intu-bation was accomplished in the nebulization groupwhen compared to the CRB group (P,0.05, Fig. 1).MAP increased 12 mmHg from the preoperative valuein the nebulization group, whereas the mean maximalrise in the CRB group was 4 mmHg, both occurringat the time of insertion of the ETT in the nostril.Within the nebulization group, when compared to thepreoperative value, MAP showed a significant rise oninsertion of the ETT into the nostril till the ETT waspassed across the glottic aperture (P,0.05, Fig. 1). Nosignificant rise in MAP was observed in the CRBgroup at any given time interval (P,0.05).

Of the patients, 79% in the nebulization group and83% in the CRB group reported the procedure asbeing comfortable or causing minimal discomfort(Table 2)

Nasal bleeding was present in 5 patients in the neb-ulization group and 4 patients in the CRB group(P.0.05). No other local or systemic complication wasobserved.

Table 2

Patients’ assessment of the degree of discomfort.

NEB group CRB groupDegree of discomfort (nΩ24) (nΩ24)

No discomfort (0) 6 9Mild discomfort (1) 13 12Uncomfortable (2) 5 3Extremely uncomfortable (3) 0 0

NEB groupΩNebulization group; CRB groupΩCombined regionalblock group.

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Discussion

Awake FNI was accomplished in all patients in bothgroups. In none of the patients had the procedure tobe abandoned because of patient discomfort. The totalintubation time was the same in both groups, indi-cating that the airways were adequately desensitized.Correspondingly, the patients’ own assessment of dis-comfort did not reveal any significant difference be-tween the two groups. This study demonstrated thatnebulization and combined regional blocks providedsatisfactory anaesthesia of the upper airway forawake FNI. However, the grimace score, the airwayreactivity score and the cardiovascular parameters re-corded at various time points indicated that patientsbelonging to the CRB group were more comfortableand haemodynamically stable.

Application of lignocaine-soaked cotton swabs inthe nose not only provided better anaesthesia of thenasal mucosa than nebulization but also had the ad-vantage of simultaneously verifying the nasal patency.Furthermore, secretions could be removed from thenasal cavity, allowing a clear vision (5). Othermethods described for anaesthetizing the nasal mu-cosa include application of lignocaine gel and ligno-caine spray. Lignocaine gel causes obscurity of visionand spraying of the anaesthetic on the nasal mucosahas been reported as being highly unpleasant for thepatient (5, 6).

A combination of bilateral SLNB and TLB was moreeffective in suppressing the cough response than neb-ulization of lignocaine. Graham et al. (7) reportedbetter laryngotracheal anaesthesia following translar-yngeal injection of lignocaine when compared to neb-ulization. Ovassapian (1) has reported satisfactory in-tubating conditions with TLB and nasal anaesthesiain a large series of 1686 cases of awake fibreoptic naso-tracheal intubations. Failure of intubations occurredin 24 cases, of which 14 were attributed to inadequatetopical anaesthesia. Randell et al. (8) reported that lar-yngeal reflexes remain distressing when TLB alone isused in combination with topical anaesthesia of thenose. Addition of 20 mg/kg of alfentanil to TLB andtopical nasal anaesthesia completely obtunds the lar-yngeal reflexes, but at the expense of respiratory de-pression. We combined TLB and topical nasal anaes-thesia with bilateral SLNB in an attempt to achievetotal anaesthesia above and below the glottis. SLNBeffectively blocks the sensory supply to the supra-glottic structures, i.e. epiglottis, pyriform sinus, baseof the tongue and the mucous membrane of the larynxsuperior to the true cords (9). This represents an ex-tremely vulnerable area for patient discomfort and la-

Local anaesthesia for fibreoptic intubation

ryngospasm during airway instrumentation. TLB pre-dominately produces anaesthesia of the infraglotticmucosa. Sensory blockade above the glottis by virtueof TLB is solely dependent upon the magnitude of thecough response generated by the patient to bring upthe local anaesthetic on the supraglottic structures(10). Invariably, this would result in partial sensoryblock if the cough intensity were blunted by local an-aesthetic. Inadequate anaesthesia of the supraglotticregion can cause a high incidence of laryngospasmand bronchospasm during airway manipulation (1). Itis therefore prudent to combine TLB with SLNB fortotal anaesthesia of the supraglottic and infraglotticregions.

Our study has demonstrated the advantage of totalairway anaesthesia using SLNB with TLB and topicalnasal anaesthesia, in significantly attenuating the HRresponse and limiting its duration. Nebulization oflignocaine for the same purpose had no effect on themagnitude of the HR response, but had some advan-tage in producing shorter duration of pressor re-sponse. Similar decrease in the magnitude and dur-ation of the pressor response had been demonstratedby Kautto and Heinonen (11) in their group of pa-tients receiving nebulized lignocaine. Ovassapian etal. (12), using 4% lignocaine for TLB and 6% cocainefor nasal application for FNI, reported a mean maxi-mum rise of 14 beats/min in the HR with 12.2% ofthe patients showing an increase of more than 30 be-ats/min. The rise in MAP was significantly dimin-ished in the CRB group of patients in our study. De-spite the addition of alfentanil (20 mg/kg) to TLB andnasal anaesthesia, Randell et al. (8) had recorded asignificant rise in blood pressure. In contrast, Hawk-yard et al. reported complete attenuation of hyperten-sive response to awake FNI when fentanyl (50–100 mg)was used in conjunction with nasal anaesthesia andTLB (13). However, the technique of endotracheal in-tubation was different from that used in the controlgroup in their study in several aspects. The investi-gators in that study had compared conventional oro-tracheal intubation performed under general anaes-thesia with FNI, which had probably contributed tothe contradictory results.

The drawback of our study has been the omissionof plasma lignocaine level estimation. Nevertheless,the mean dose of lignocaine used for patients in ourstudy was 177∫24 mg (3.57 mg/kg) in the nebulizedgroup and 198∫22 mg (3.91 mg/kg) in the CRBgroup, which was far below the maximum safe doserecommended for lignocaine (14). None of the pa-tients in either group had any clinical evidence oflignocaine toxicity. Efthimiou et al. (15) in their study

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used 9.3 mg/kg of lignocaine (nasal, oropharyngealand laryngeal spray of 10% lignocaine), which re-sulted in a mean peak plasma level of 2.9 mg/ml. In 2patients the plasma levels exceeded 5 mg/ml, butwithout clinical evidence of any toxicity. Bigeleisen etal. (3) utilized 7 mg/kg of lignocaine (bilateral SLNB,TLB and nasal spray), resulting in a mean peakplasma level of 4.06 mg/ml at 10 min after the TLB.Plasma levels of more than 5 mg/ml occurred in onlyone of the patients, without any clinical toxicity. Neb-ulization of lignocaine has been reported to result inlow peak plasma concentrations of lignocaine, as com-pared to other techniques. This is attributed to the lossof the nebulized solution (up to 50%) with continuousnebulization during spontaneous breathing (16, 17).Parkes et al. (18) demonstrated that nebulization of 6mg/kg of 10% lignocaine resulted in a peak plasmalevel of only 0.2 mg/ml, which occurred 30 min fol-lowing nebulization.

To summarize, both nebulization of 4% lignocaineand combined regional blockade produce satisfactoryanaesthesia of the upper airway, but patients withCRB remain far more comfortable and haemodyn-amically stable during the procedure. Nevertheless,nebulization still remains an attractive choice whensuperior laryngeal nerve block and translaryngealblock are not possible due to obscured anatomicallandmarks.

References

1. Ovassapian A. Fibreoptic airway endoscopy in anaesthesiaand critical care. 1st edn. New York: Raven Press, 1990: 45–53.

2. Morris I. Fibreoptic intubation. Can J Anaesth 1994: 41: 996–1008.

3. Bigeleisen PE, Schisler JQ, Finucane BT. Plasma lidocainelevels following transtracheal injection during topical anaes-thesia of the upper airway. Can J Anaesth 1998: 45: S95–S96.

4. Gal TJ. Airway anesthesia in normal subjects following top-ical anesthesia with ultrasonic aerosols of 4% lignocaine.Anesth Analg 1980: 59: 123–129.

5. Randell T, Hankala AY, Valli H, Lindgren L. Topical anaes-thesia of the nasal mucosa for fibreoptic airway endoscopy.Br J Anaesth 1992: 68: 164–167.

6. Gove RI, Wiggins J, Stableforth DE. A study of the use ofultrasonically nebulized lignocaine for local anaesthesiaduring fibreoptic bronchoscopy. Br J Dis Chest 1985: 79: 49–59.

7. Graham DR, Clague J, Earis JE. Comparison of threemethods used to achieve local anaesthesia for fibreopticbronchoscopy. Chest 1992: 102: 704–707.

8. Randell T, Valli H, Lindgren L. Effects of alfetanil on theresponses to awake fibreoptic nasotracheal intubation. ActaAnaesthesiol Scand 1990: 34: 59–62.

9. Allan PR, Han DG. Preparation of the patient for awake fib-eroptic intubation. Anesth Clin North Am 1991: 9: 69–81.

10. Walts IF. Anaesthesia of the larynx in a patient with a fullstomach. JAMA 1965: 192: 705–706.

P. Kundra et al.

11. Kautto UM, Heinonen J. Attenuation of circulatory responseto laryngoscopy and tracheal intubation: A comparison oftwo methods of topical anaesthesia. Acta Anaesthesiol Scand1982: 26: 599–602.

12. Ovassapian A, Yelich SJ, Dykes HM, Brunner E. Fiberopticnasotracheal intubation – Incidence and causes of failure.Anesth Analg 1983: 62: 692–695.

13. Hawkyard SJ, Morrison A, Doyle LA, Croton RS, Wake PN.Attenuating the hypertensive response to laryngoscopy andendotracheal intubation using awake fibreoptic intubation.Acta Anaesthesiol Scand 1992: 36: 1–4.

14. Wu FL, Razaghi A, Souney PF. Seizure after lidocaine forbronchoscopy: Case report and review of lidocaine in air-way anaesthesia. Pharmacotherapy 1993: 13: 72–76.

15. Efthimiou J, Higenbotham T, Holt D, Cochrane GM. Plasmaconcentrations of lignocaine during fibreoptic bronchoscopy.Thorax 1982: 37: 68–71.

16. Kirkpatrick MB, Sanders RV, Bass JB. Physiologic effects and

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serum lignocaine concentrations after inhalation of lidocainefrom a compressed gas powered jet nebulizer. Am Rev RespirDis 1987: 136: 447–448.

17. Chinn WM, Zavla DS, Ambre J. Plasma levels of lignocainefollowing nebulized aerosol administration. Chest 1977: 71:346–348.

18. Parkes SB, Butler CS, Muler R. Plasma lignocaine concen-tration following nebulization for awake intubation. AnaesthIntensive Care 1997: 25: 369–371.

Address:Dr. Pankaj KundraD – II / 21JIPMER campusPondicherry 605006India