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 .
Ó 2002 Blackwell Science Ltd, Paediatric Anaesthesia, 12, 36±42
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).
TRACHEAL INTUBATION IN CHILDREN 39
Ó 2002 Blackwell Science Ltd, Paediatric Anaesthesia, 12, 36±42
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 .
Ó 2002 Blackwell Science Ltd, Paediatric Anaesthesia, 12, 36±42
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 .
Ó 2002 Blackwell Science Ltd, Paediatric Anaesthesia, 12, 36±42
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