Download Tracheal intubation without the use of neuromuscular blocking agents

Tracheal intubation without
the use of neuromuscular
blocking agents
Tariq Alzahrani
Demonstrator
College of Medicine
King Saud University
History
• Before the early 20th century , intubation of
the trachea had been described for
conditions such as perioral tumours &
laryngeal obstruction & often using fingers
as a makeshift laryngoscope & without any
pharmacological agents.
• Insufflation of the trachea for the purpose of
ether anaesthesia was introduced in 1909 in
the USA & in 1912 in the UK.
• Neuromuscular blocking drugs to aid
tracheal intubation were first introduced into
clinical practice in 1942 in the USA.
• Before this , tracheal intubation was usually
performed under deep inhalation anaesthesia
with ether .
Introduction
• Before 1942 .
• The continuing use of this technique to
facilitate tracheal intubation with halothane &
subsequently sevofluraue is still established
, especially in paediatric practice .
• Inhalation anaesthetics , induction agents ,
lidocain , opioids .
• Indications .
Inhalational agents
Halothane & enflurane
• MACEI .
• 37 children , aged 2-6 yr , & found the MACEI
of halothane is 1.4% & found by
extrapolation that the MACEI value for 95%
of that population was 1.9% . (Yakaitis 1977)
• MACEI of enflurane is 2.9%. (Yakaitis1979)
• For both halothane & enflurane , the MACEI
appears to be about 30% greater than the
MAC value .
• Enflurane complications . (Lebwitz,Blitt,Dillon1972)
Isoflurane & Desflurane
Sevoflurane
• Children .
• Halothane largely superseded by sevoflurane in
the UK since the mid to late 1990s .
• 36 children aged 1-9ys were studied,
laryngoscopy & intubation were attempted only
after the ratio of alveolar to predetermined
inspiratory % had been maintained at greater
than 0.95 for 15 min. MACEI of sevoflurane is
2.7%. (Inomata, Watanabe,Taguchi,Okada 1994)
• 29 children , aged 2-8ys , breathing circuit was
saturated with sevoflurane 5%. The result
showed that 80 & 100% of patients underwent
smooth tracheal intubation at ETC of 4&4.5%
respectively, & that the effective
dose for 50% of the population (ED50 equivalent
to the MACEI) was 3.1% . This is 0.3-0.4 higher
than previously reported in a similar group of
patients, presumably because of the different in
the brain % as a result of a shorter intubation
time. The time taken to reach an ETC of 4.5% &
intubate averaged 210 s. (Inomata,Nishikawa 1996)
• The addition of N2O 33 & 66% has been shown
to decrease the MACEI value in children aged 17ys by 18 & 40% ,from 2.7% with sevoflurane
alone , to 2.2% & 1.6% respectively.
(Swan,Crawford,Stephens,Lerman 1999)
• 64 healthy children aged 3-10ys , undergoing
tonsillectomy :
- Group I , received sevoflurane 8% & N2O
66% in O2 .
- Group II , received propofol 3-4mg/kg
&sux 2mg/kg .
Both group were intubated at 150s by a
blinded investigator .
Excellent condition were scored in only 55% of
group I & 82% in group II.
(Thwaites,Edmends,Tomlinson,Kendall,Smith 1999)
• 120 children aged 3-12yr,sevof. 8% in N2O
60% was compared with
propofol/succinylcholine (3mg/kg & 1mg/kg)
& propofol/alfemtanil (3mg/kg & 10μg/kg) .
Patients in sevof. group were intubated after
3min, whilst the other groups were intubated
after 60 s.
Acceptable conditions were found in 97.5,87.5
&52.5% respectively.
The mean ETC just before intubation was
4.2%.This agree with the previously quoted
studies that an ETC of 2XMAC is required for
successful intubation in almost all children.
• Adult .
• In 86 ASA I or II adult patients , the MACEI
sevoflurane for 50% of the population was
4.5%. (Kimuru,Watanabe,Asakura,Inomata,Okada,Taguchi
1994)
• The authors account for this difference by
the irritation & subsequent coughing caused
by the cuff of adult tracheal tube & the fact
that children have a relatively greater brain
perfusion & quicker uptake .
• 120 adult patients:
- Group I , received thiop. 5mg/kg & sux.
1mg/kg .
- Group II , received sevof. 8% in N2O 66%.
- Group I, were intubated at 1min & achieved
almost 100% success rate with good or
excellent condition .
Group II ,breathed 3 V.C breaths in a primed
circuit followed by 4min normal breathing to
achieve almost the same result.
(Imaroon,Pitimana,Prechawi,Anusit,Somcharoen,Caiyarroj
2001)
• Pretreated agroup of 80 ASA I-II adult with
fentanyl 1,2& 4 μg/kg given 4min before
intubation , MACEI of sevof. of 2.07 , 1.45 &
1.37% respectively ,compared with 3.55%
without fentanyl. (Katoh,Nakajima,Moriwaki 1999)
Difficult airway
•
Sevoflurane has a lower blood gas
solubility & is less likely to cause cardiac
depression or arrhythmias than halothane.
• These patients have been managed in one
of two ways:
1. By increasing the inspired % of sevof. In a
stepwise way.
2. High % induction.
• Because of the relatively fast onset of sevof.
,some authors advise caution with its use in
difficult airway , noting that speed of
induction may not be desirable in some
circumstances because of increased risk of
respiratory depression . (Board 1998) (Davies 1996).
lidocaine
• Reported to be a useful I.V & topical adjunct
to facilitate tracheal intubation , both on its
own & with different short acting opioid ,in
doses of 1-2 mg/kg .
• In doses of 1mg/kg I.V lidocain has been
shown to halve the dose of alfentanil or
remifentanil needed to produce comparable
intubating conditions. (Davidson,Gillespie 1993)
(Wood,Grant,Harten,Nobel,Davidson 1998)
• Several papers have also examined the
effectiveness of I.V lidocain to suppress the
cough reflex , optimum dose was 2mg/kg
administered I.V at 1 min before intubation.
(Yukioka,Yoshimoto,Nishimura,Fujimuri1985)
• It dose not alter pressor response to
laryngoscopy & tracheal intubation .
(Hamill,Bedford,Weaver,Colohan
1981)(Laurito,Bangham,Becker,Polek,Regiler 1988)
Induction agents
• Thiopental , in 1948 , lewis described a
series of 200 patients who received either a
blind nasal or direct oral intubation after
thiopental 500-750mg. There were 2 failures
in the blind nasal group & 6 in the direct
laryngoscopy group .
He encountered severe problems with
coughing, although the quality of overall
intubating conditions was not specified as
no scoring systems were used.
• Propofol provides better jaw relaxation &
attenuation of laryngeal reflexes than
thiopental . (McKeating,Bali,Dundee 1988)
• When used alone for tracheal intubation,
2.5mg/kg provided satisfactory condition in
96% patients & ideal intubating condition in
60% patients. (Keaveny,Knell 1988)
Opioids
fentanly
• Has been shown to blunt the pressor to
laryngosccopy & intubation optimally 5
min after administration. (Ko,Kim,Song 1998)
• In a study of 60 ASA I or II children ,
fentanyl 3μg/kg given 5 min before
propofol 3 mg/kg was the optimal dose
regime & resulted in satisfactory
intubating conditions in 75%of patients.
(De Fatima,Da Silva,Poterio,Cremonesi 2001)
Alfentanil
• Alfentanil has been used successfully as an
adjunct to blunt the pressor response .
• Many studies done , it varies in design , type
of premedication, dose of alfentanil (between
10 μg/kg & 50 μg/kg)& clinical end-point ,
making it difficult to decide on the best drug
regimen.
• Alfentanil has been used successfully in
acase of a difficult airway after both fibreoptic intubation & deep inhalational
anaesthesia with halothane had failed.
(McDonald 1993)
• The authors used alfentanil 25 μg/kg
followed by propofol 1mg/kg to visualize the
glottis, & stated that the effects of alfentanil
could have been readily antagonized by
naloxone if necessary.
Remifentanil
• Has a similar clinical onset time of alfentanil
& has also been found to blunt the pressor
response to tracheal intubation.
• Many studies done , it veries in the timing of
drug administration , study design & doses
varying between 0.5 & 5μg/kg.
• A rapid sequence induction using
remifentanil has been described in a 12yr old
child with a potentially difficult airway , after
a gunshot wound & he had a family history of
malignant hyperpyrexia . The patient
received propofol 3 mg/kg & remifentanil
4μg/kg & underwent uneventful
laryngoscopy & subsequent anaesthesia .
(Haughton,Turley,Pollock 1999)
Conclusions
• The literature describes successful
techniques to intubate the trachea
without the use of neuromuscular
blocking agents under G.A.
• The technique offers a useful alternative
when the neuromuscular blocking
agents are either contraindicated or
undesirable .
• It is difficult to make any particular
recommendation because clinical
opinion is often based on personal
experience & dose regimes may vary
between clinicians.
• Sevoflurane is best inhaled in a
stepwise way , until the ETC is at least
2 x MAC .
• The use of alfentanil & remifentanil to
facilitate intubation of trachea is
particularly helpful in paediatric ENT
procedures (alfentanil 20μg/kg ,
remifentanil 2μg/kg).
• The addition of lidocaine achieves
better intubating condition mainly
because of suppression of the cough
reflex & adds little to ease of
laryngoscopy or passage of a tracheal
tube through the vocal cords.
• Because of the diversity in study
methods & interpretation of the quality
of tracheal intubation, each technique
& subsequent results must be
interpreted within the clinical situation
described.