A survey of practice of tracheal intubation without muscle relaxant in paediatric patients

A survey of practice of tracheal intubationwithout muscle relaxant in paediatric patients

LIONEL SIMON M DM D*, KARIM J. BOUCEBCI M DM D*, GILLES

ORLIAGUET M DM D², JEAN-VINCENT AUBINEAU M DM D³,

JEAN-MICHEL DEVYS M DM D§ AND ANNE-MARIE

DUBOUSSET M DM D±*HoÃpital Saint Vincent de Paul, Assistance Publique-HoÃpitaux de Paris, Paris, ²HoÃpital Necker-Enfants malades, Assistance Publique-HoÃpitaux de Paris, Paris, ³HoÃpital Armand Trousseau,Assistance Publique-HoÃpitaux de Paris, Paris, §HoÃpital Robert DebreÂ, Assistance Publique-HoÃpitaux de Paris, Paris and ±HoÃpital du Kremlin BiceÃtre, Assistance Publique-HoÃpitaux deParis, Paris, France

SummaryBackground: Because of the renewed interest in intubation in children

without relaxants, over a period of 1 month, the anaesthesiologists of

®ve paediatric universitary teaching hospitals were asked to complete

a questionnaire each time they performed a tracheal intubation

without muscle relaxant.

Methods: Intubating conditions were assessed with ®ve items. Each

item was graded on a four-point scale. Intubating conditions were

judged acceptable when all items scored 2 or less. Episodes of oxygen

desaturation and failed intubations were noted. Data are expressed as

mean � SD (extremes).

Results: Five hundred and two questionnaires were completed during

the study period. Children were aged 61 � 50 (1±180) months old.

Induction of anaesthesia was performed with sevo¯urane for 62.6% of

the children (endtidal concentration 5.9 � 1.5%) and propofol for

28.9% (dose 5.8 � 4.2 mgákg±1). Opioids were associated with these

hypnotics in 53.2% of the children. Tracheal intubation was successful

in 87.1% of the children. Sevo¯urane produced better intubating

conditions than propofol. Sevo¯urane requirements for tracheal

intubation may be higher in infants aged less than 6 months old than

in older children. A severe decrease in SpO2 (£ 90%) was observed in

15.9% of the infants aged less than 1 year old and in 1.7% of the

children, respectively (P < 0.0001).

Conclusions: Sevo¯urane is the most commonly used agent for tracheal

intubation without relaxants with higher doses being required in

infants aged less than 6 months. Propofol, even with opioids, was not

so successful.

Keywords: tracheal intubation; sevo¯urane; propofol; children

Correspondence to: Dr Lionel Simon sadly is now deceased.

Paediatric Anaesthesia 2002 12: 36±42

36 Ó 2002 Blackwell Science Ltd

Introduction

There is a renewed interest in tracheal intubation

without a muscle relaxant among anaesthesiolo-

gists, even though this technique has been used for

many years in paediatric anaesthesia. In a recent

survey, Politis et al. noted that inhaled anaesthetic

without muscle relaxant was the most frequently

used technique when intubating healthy fasted

paediatric patients (1). These authors mentioned

that they could not ®nd published data on the

frequency of use or the safety of this technique.

Many authors reported acceptable conditions for

tracheal intubation in 95±100% of the children

when using halothane alone (2,3) or associated

with opioids (4). Acceptable intubating conditions

seem more dif®cult to achieve after induction of

anaesthesia with propofol associated with alfentanil

(2,5). In a recent study, the ®rst attempt at tracheal

intubation was unsuccessful in 20% of children

aged 1±3 years after induction of anaesthesia with

propofol 3 mgákg±1 and alfentanil 10 lgákg±1. In the

same study, all the procedures were successful

when induction was performed with halothane 5%

(2). Hansen et al. obtained 94±100% acceptable

intubating conditions in young premedicated chil-

dren using a combination of halothane (1 or 2%)

and propofol (3 mgákg)1) (3). The technique that

should be used to perform tracheal intubation

without muscle relaxant is still debated (2,4,5). Thus,

we prospectively surveyed the procedures used by

anaesthesiologists in ®ve paediatric university teach-

ing hospitals for tracheal intubation without muscle

relaxant.

Materials and methods

A questionnaire was designed and all the details and

modalities of the survey were discussed with the

anaesthesiologists of ®ve paediatric university teach-

ing hospitals. Over a period of 1 month, the anaes-

thesiologists of the surveyed hospitals were asked to

answer this questionnaire for every tracheal intuba-

tion performed without muscle relaxant. In each

hospital, a coordinating anaesthesiologist collected

all completed questionnaires daily and checked for

incomplete ones. All questionnaires were anony-

mous. Data were collected on a computer every

week throughout the study period. The question-

naire collected information on: (i) demographics

(age, sex, weight, physical ASA status); (ii) charac-

teristics of the anaesthetic procedure (intravenous or

inhaled agent, dose, size of the tube, cuffed or

uncuffed tracheal tube); (iii) intubating conditions

assessed by a ®ve-item score as previously reported

by Helbo-Hansen et al. (6) (Table 1); and (iv) com-

plications that could be related to the technique

(decrease in SpO2 during intubation attempt, stridor

after extubation). Decrease in SpO2 during the

procedure was considered to represent an adverse

effect only when SpO2 fell to 90% or less. The data

were analysed using a MAC-value of sevo¯urane of

3.2% in infants aged 1±6 months and 2.5% after

6 months (7). The appropriate size of the tracheal

tube was checked in every child which developed

postoperative croup stridor, using the formula pro-

posed by Khine et al. (8): size (mm internal diam-

eter) � (age/4) + 3 for cuffed tubes and size (mm

internal diameter) � (age/4) + 4 for uncuffed tubes.

Results are expressed as mean � SDSD. Data were

analysed using chi-squared or an unpaired Student's

t-test as appropriate.

Results

Five hundred and two complete questionnaires were

obtained from the ®ve paediatric hospitals where the

study was conducted (Table 2). These 502 question-

naires described the procedure used for tracheal

intubation without muscle relaxant in 82 infants

(< 1 year old), 208 young children (1±5 years old)

and 212 older children (> 5±15 years old). Of these,

61.2% were premedicated with either benzodiazep-

ine or hydroxyzine. Clinical criteria that might

Table 1Score used to assess the ease of tracheal intubation. Intubatingconditions were considered to be acceptable when every item hada score £ 2

Score

Items 1 2 3 4

Laryngoscopy Easy Fair Dif®cult ImpossibleVocal cords Open Moving Closing ClosedCoughing None Slight Moderate SevereJaw relaxation Complete Slight Stiff RigidLimb movements None Slight Moderate Severe

Adapted from Helbo-Hansen et al. (6).

TRACHEAL INTUBATION IN CHILDREN 37

Ó 2002 Blackwell Science Ltd, Paediatric Anaesthesia, 12, 36±42

predispose to dif®cult intubation were noticed pre-

operatively in 15 children and tracheal intubation

was dif®cult in only three. Either sevo¯urane,

propofol or both drugs were used in 96.6% of the

procedures (Table 3). Propofol induction was most

commonly performed in older children whereas

inhalational anaesthesia was preferred in the younger

(Figure 1). In particular, propofol was only used in

®ve infants aged less than 1 year. The mean time

interval between propofol injection and the ®rst

laryngoscopy was 2.1 � 1.3 min. Sevo¯urane was

administered 6.1 � 6.3 min before tracheal intuba-

tion, but this period included the time necessary to

obtain venous access. The endtidal concentration of

sevo¯urane at the time of intubation was 6.1 � 1.2%,

5.8 � 1.6%, 6.0 � 1.6%, 5.7 � 1.5% and 5.8 � 1.6%

in patients aged 1±6 months, 7±12 months,

13±36 months, 37 months to 5 years and > 5 years,

respectively. Thus, infants aged less than 6 months

received 1.9 � 0.5 MAC of sevo¯urane whereas the

DrugDose

administered

Success rate atthe ®rst attempt for

tracheal intubation (%)

Propofol (mgákg)1)Propofol (P) alone (n = 22) 6.27 � 2.69 77P + Opioids (n = 123) 5.75 � 4.39 85

Sevo¯urane (endtidal concentration percentage)Sevo¯urane (S) + O2 (n = 99) 6.5 � 1.3 91S + 50% N2O (n = 94) 6.4 � 1.4 92S + Opioids (n = 77) 5.0 � 1.2 86S + Opioids + N2O (n = 44) 5.3 � 1.7 86

Table 3Main drugs used for induction ofanaesthesia before performingtracheal intubation withoutmuscle relaxant

Table 2Demographic and intubation data

Sevo¯urane Propofol

Number of procedures (n) 314 145Age of the children (months) (mean � SDSD) 46 � 44 114 � 62*Weight of the children (kg) (mean � SDSD) 16 � 10 34 � 20*Patients with predicted

dif®cult intubation criteria (n)9 6

Premedicated patients (%) 63.7 55.5Tracheal intubation by a

junior anaesthetist (%)35.5 40.1

Five hundred and two questionnaires were analysed. Sevo¯urane,propofol or both drugs were used in 96.6% of the patients. Themain characteristics are given for infants or children who receivedone of these two hypnotics for tracheal intubation. * P < 0.05when compared with the sevo¯urane group.

90

0< 1 year

Suc

cess

rat

e (%

)

50

80

70

60

40

30

20

10

3/5

(b)

1–5 years

23/27

> 5 years

93/113

100

01–6

Suc

cess

rat

e (%

)

50

80

70

60

40

30

20

10

33/44

(a)

90

7–12

43/48

13–36

80/86

37–60

52/58

zz

72/78

Age (months)

*

Figure 1(a) Success rate (%) for tracheal intubation at the ®rst attempt afterinduction of anaesthesia with sevo¯urane. The total number ofpatients in each group is given above the columns. A lowersuccess rate was observed in infants aged less than 6 months oldcompared with the others (P � 0.001, chi-squared). (b) Successrate (%) for tracheal intubation at the ®rst attempt in infants agedless than 1 year, children aged 1±5 years and aged more than5 years after induction of anaesthesia with propofol. The totalnumber of patients in each group is given above the columns. Nostatistical analysis could be performed because of the smallnumber of infants in the ®rst group.

38 L. SIMON ET AL .


older patients received 2.3 � 0.6 MAC of sevo¯ura-

ne (P � 0.002, unpaired Student's t-test). A combi-

nation of sevo¯urane and propofol was used in 26

patients (5.2%). Among the 17 children who

received neither sevo¯urane nor propofol to induce

anaesthesia, nine received halothane and ®ve

received thiopentone. Topical lidocaine was applied

in 43 patients, 18 of them received sevo¯urane

(4.2 � 3 years, weighing 17 � 10 kg, tracheal intuba-

tion was successful at the ®rst attempt in 17)

whereas propofol was used in the other 25 patients

(11 � 4 years patients, weighing 39 � 19 kg, tracheal

intubation was successful at the ®rst attempt in 23).

Tracheal intubation was successful at the ®rst

attempt in 87.1% of the patients. This rate was

signi®cantly lower in infants (< 1 years old) than in

children (³ 1 years old) (78% versus 89%,

P � 0.008). Tracheal intubation was successful at

the ®rst attempt in 84.1% and in 89.2% of the

patients when using propofol or sevo¯urane,

respectively. This difference was not signi®cant

(P � 0.13). Considering these successful procedures,

good intubating conditions (every item scored £ 2)

were noted in 71% of the patients anaesthetized

with propofol and in 97% of the patients anaesthet-

ized with sevo¯urane, respectively (P < 0.001, chi-

squared) (Table 4). Opioids or nitrous oxide did not

improve signi®cantly either success rate for tracheal

intubation or intubating conditions in successful

procedures. The rate of successful procedures was

comparable between senior, junior and nurse ana-

esthesiologists: 82%, 88% and 90%, respectively.

A signi®cant decrease in SpO2 (£ 90%) was noted in

13 infants and seven children during tracheal intu-

bation (P < 0.0001).

Tracheal extubation was performed rapidly after

surgery in 490 patients. Stridor was observed on

extubation in eight patients out of 490. The incidence

was 2.1% (3/143) in patients with an uncuffed tube

and 1.4% (5/347) in those with a cuffed tube. The

size of the tracheal tube was considered appropriate

in all children who developed stridor on extubation.

However, the ®rst attempt at tracheal intubation was

unsuccessful in four patients among these eight

because of either a dif®cult laryngoscopy (the item

`laryngoscopy' had been scored 3 in these four

children) or closed vocal cords (the item `vocal

cords' had been scored 4 in one child).

Discussion

In the present survey, propofol or sevo¯urane were

used for more than 95% of the children. Intravenous

induction of anaesthesia was used in older children

whereas inhalational anaesthesia was often pre-

ferred in infants. The success rate for tracheal

intubation after sevo¯urane induction was lower in

infants aged less than 6 months than in older

patients. Because the endtidal concentrations of

sevo¯urane were comparable between the different

ages, this result may be partly explained by the

lower potency of sevo¯urane in infants aged less

than 6 months than in older patients. To our know-

ledge, the in¯uence of age on the sevo¯urane

requirements in paediatric patients for tracheal

intubation has never been reported. The ED50 and

the ED95 endtidal sevo¯urane concentration for

tracheal intubation in children aged 1±8 years have

been reported to be 2.69% (95% con®dence interval

2.23±3.37%) (9) and 3.54 � 0.25% (10), respectively.

When 33% or 66% nitrous oxide is added to

sevo¯urane, its MAC for tracheal intubation decrea-

ses by 18% and 40%, respectively (10). When

induction of anaesthesia is performed with a rapid

sequence (5% sevo¯urane inspired in oxygen), the

endtidal concentrations of sevo¯urane required for

tracheal intubation must be much higher than those

achieved after a long stabilization period. These

concentrations are also extremely variable from one

child to another (11).

Halothane, which has been a gold standard for

induction of anaesthesia in paediatric patients for

Table 4Intubating conditions observed in 459 infants or children.Anaesthesia was induced either by inhalation of sevo¯urane orintravenously with propofol. Intubating conditions wereconsidered unsatisfactory when at least one of the ®ve itemshad a score > 2

Percent of children with ascore > 2 for the corresponding item

Items Propofol (n = 145) Sevo¯urane (n = 314)

Laryngoscopy 6.1 1.0*Vocal cords 8.8 6.4Cough 21.1 1.9*Relaxation 2.7 0.0Movements 17.0 1.0*

* P < 0.05 compared with the group of patients who receivedpropofol for induction of anaesthesia (chi-squared).



many years, was hardly used in this survey. Cardiac

rhythm disturbances and decreased arterial pressure

are related to the use of high concentrations of

halothane. Halothane may induce severe dysrhyth-

mias that have been related to anaesthetic deaths

(12). Several authors used high concentrations of

sevo¯urane to facilitate either laryngeal mask air-

way (LMATM) insertion or tracheal intubation. In

these studies, the use of 5±8% sevo¯urane concen-

trations for induction of anaesthesia did not result in

dysrhythmia, bradycardia or hypotension requiring

treatment (11,13,14). From this survey, sevo¯urane

appears a more attractive drug than halothane for

tracheal intubation in children.

The mean dose of propofol used in this survey was

greater than usually reported in the literature for the

induction of anaesthesia when muscle relaxants are

used. Despite these high doses, intubating conditions

were not as good as those obtained after inhalational

induction. As previously observed by other authors,

the frequently poor intubating conditions after pro-

pofol and alfentanil does not seem to signi®cantly

affect the success rate at the ®rst attempt (2,5). Using

3 mgákg±1 propofol and 10 lgákg±1 alfentanil, Blair

et al. observed acceptable intubating conditions in

only 21 of 40 children aged 3±12 years (15). Con-

versely, these authors could frequently achieve

acceptable intubating conditions in children receiv-

ing either 8% sevo¯urane in 60% nitrous oxide or

propofol and succinylcholine (35/40 and 39/40,

respectively). A mean propofol induction dose of

2.8 mgákg±1 intravenously is required for the loss of

the eyelash re¯ex in 90% of premedicated children

(16). The dose of propofol required for satisfactory

LMA insertion in 90% unpremedicated children

has been determined to range between 4.7 and

6.8 mgákg±1 (17) and the hypnotic requirements for

tracheal intubation are considered greater than those

for laryngeal mask airway insertion (18). Steyn et al.

compared suxamethonium 1.5 mgákg±1 and alfentanil

15 lgákg±1 to facilitate tracheal intubation in children

after induction of anaesthesia with 3±4 mgákg±1 prop-

ofol. Although the rate of acceptable conditions was

comparable between the two groups (87% versus

80% for suxamethonium and alfentanil, respectively,

NS), coughing and movements of the limbs were

frequently observed in the alfentanil group (19). In

adults, Kazama et al. showed that the blood propofol

concentrations at which 95% of patients do not

exhibit somatic response to tracheal intubation is

36.5 lgáml±1 (20). Such high propofol blood concen-

trations are greater than those observed after a single

2.5 or 3 mgákg±1 i.v. bolus of propofol (21). It is not

surprising that several authors reported less than

80% good intubating conditions after induction of

anaesthesia by 3 mgákg±1 propofol and opioids in

children (2,22). Wodey et al. studied the haemody-

namic effects of a single 6.1 � 0.6 mgákg±1 i.v. bolus of

propofol in paediatric patients (23). Although they

were associated with a transient and moderate

decrease in systolic (±15%) arterial pressure, such

propofol induction doses did not alter heart rate, left

ventricular shortening fraction or cardiac index

assessed by echocardiography. Moreover, a larger

apparent volume of distribution for propofol is

consistent with a higher induction dose requirement

in children than in adults (24). All these data support

the use of high doses of propofol (³ 5 mgákg±1) to

allow good intubating conditions in paediatric

patients.

In adults, propofol may be given by computer

assisted continuous infusion pumps. Half time for

equilibration between blood and brain propofol

concentrations was determined at 2.9 min and, using

BIS, the half time for the plasma-effect-site equili-

bration was ³ 2.30 min (24). In our survey, propofol

was always given as an i.v. bolus and the mean time

between propofol injection and the ®rst attempt for

tracheal intubation was 2.1 min. Pharmacokinetic

model-driven devices are not available for paediatric

patients but we can hypothetize that such computer

assisted pumps may be useful to improve the

management of tracheal intubation without muscle

relaxant in children after propofol induction of

anaesthesia.

Lidocaine-spray was used in only 43 patients.

Topical application of lidocaine has been reported

to signi®cantly improve intubating conditions after

propofol-alfentanil induction in adults (25).

Recently, it was also reported to be an interesting

adjunct to tracheal intubation without muscle

relaxant in paediatric patients (26). Moreover, the

laryngeal spraying of 8±16 mg lidocaine (one or

two sprays using a 5% sprayer) in paediatric

patients does not increase the plasma lidocaine

concentrations to a toxic level (27). It would be

interesting to assess and/or to develop the use of

topical lidocaine to improve intubating conditions

40 L. SIMON ET AL .


in paediatric patients when muscle relaxant are not

used.

Stridor has been frequently reported in children

after tracheal intubation. Excessive size of the tra-

cheal tube (28) and duration of anaesthesia (29)

increase the incidence of this complication. In the

present survey, it was observed in 1.6% of the

patients. To our knowledge, the absence of muscle

relaxants for tracheal intubation has never been

reported to increase the risk of postextubation

laryngeal oedema. However, the rate of failed

intubation was very high (four of eight) in the

patients who developed stridor. We suggest that

insuf®cient relaxation during tracheal intubation

without muscle relaxant may have increased the

rate of this complication. As previously reported by

other authors (8), cuffed tracheal tubes were not

associated with an increased incidence of stridor in

our survey.

In conclusion, sevo¯urane seems to be the anaes-

thetic agent most frequently used for tracheal intu-

bation without muscle relaxant in paediatric

patients. Sevo¯urane requirements for tracheal intu-

bation may be higher in infants aged less than

6 months than in older ones. When using appropri-

ate concentrations, sevo¯urane either alone or asso-

ciated with opioids, allows an almost 90% rate of

uneventful and successful procedures. This rate was

not obtained with propofol, even when a high dose

of propofol was associated with opioids. The devel-

opment of pharmacokinetic model-driven pumps

may help to improve the use of propofol for tracheal

intubation in children. Nevertheless, the advantages

and disadvantages of using a muscle relaxant, or

not, for tracheal intubation of healthy, fasted children

should be evaluated by a randomized study.

Acknowledgements

We thank Drs I. Murat, J. Hamza and J.X. Mazoit for

reading of the manuscript.

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Accepted 15 February 2001

42 L. SIMON ET AL .


A survey of practice of tracheal intubation without muscle relaxant in paediatric patients

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