Tracheal intubation in routine practice with and without muscular relaxation: an observational study

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Tracheal intubation in routine practice with and
without muscular relaxation an observational
study

• European Journal of Anesthesiology
• 200522672-677
• Anes R ???

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Introduction
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• Standard practice to use muscle relaxant for
  excellent intubation conditions in routine
  anesthesia
• Avoid morbidity associated with difficult
  intubation (injuries to airway)
• Use of muscle relaxants anaphylaxis
• Propofol causes significant suppression of
  laryngeal reflexes has renewed interest in
  relaxant-free techniques for tracheal intubation

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• Aim of study to describe the intubation
  conditions routinely employed in the practice and
  to assess the safety of this technique in a
  large, consecutive group of elective surgical
  patients

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Methods
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• Inclusion all adult patients (gt 18 yr) scheduled
  for orthopedics, abdominal, vascular, breast and
  ear surgery under GA
• Exclusion planned use of hypnotic other than
  propofol, laryngeal symptoms before surgery, NG
  (), non-scheduled surgery

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• Absence of laryngeal symptoms was confirmed and
  Mallampati classification determined by attending
  anesthesiologist during pre-op airway assessment

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• Standard induction
  midazolam 0.02-0.05 mg/kg sulfentanil
  0.2-0.4 µg/kg
• 2 mins later, propofol injected i.v. over 60s
• One of 11 certified anesthesiologists or 10
  certified nurse anesthetists
• Maintain desflurane N2O 60 in oxygen,
  intermittent bolus of sulfentanil
• NM blocking agents used as appropriate for
  surgery

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• Modified Cormack and Lehane classification
• Grade 3 or 4 difficult laryngoscopy
• Intubating scoring was evaluated according to the
  consensus conference of Good Clinical Research
  Practice in Studies of Neuromuscular Blocking
  Agents

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Intubation with relaxant

• Muscle relaxant used when it was required for the
  surgical procedure and/or in patients at risk for
  hemodynamic instability
• At the discretion of attending anesthesiologist
• Atracurium 0.5 mg/kg i.v.
• Intubation when no response to TOF at adductor
  pollicis
• Intubation score assessed at time of intubation

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Intubation without relaxant

• 60 sec after propofol, initial laryngoscopy
  performed and topical anesthesia was applied (5
  lidocaine 2 sprays per 10 kg to larynx and
  trachea)
• Intubation then performed after intubation score
  was assessed 2 min after the topical anesthesia
• Relaxant could be used to improve intubating
  conditions if at lease one unacceptable variable
  ()

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Assessment of complications

• Induction-related hypotension
• PAR, and subsequent hospitalization, one
  anesthesiologist (unaware of intubation
  condition), asked patients for experience of
  throat discomfort or dysphonia since surgery
• Laryngeal symptoms (), daily follow-up was
  performed until complete resolution
• Dysphonia persisted the day after surgery, vocal
  cords were examined using fiberoptic laryngoscopy
  by ENT Dr

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Results
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• 612 patients recorded, between March and July 2003

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32
68
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• No intubation failures
• Difficult laryngoscopy (Cormack gt 2) was found in
  47 patient (9)
• Intubating Score was assessed in 565 remaining
  patients

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98.4
1.2
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184 patients (33)
Female 60 45
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• Vocal cord sequela found in 4 patients ( 3 in
  relaxant and 1 in relaxant-free group)
• Follow-up exam 2 weeks later revealed no
  persistent sequela
• Induction-related hypotension female ( 68
  vs. 46)

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Discussion
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• Technique avoiding muscle relaxants does not
  associated with poor conditions for tracheal
  intubation, or postoperative laryngeal symptoms
• To attempt to reduce the use of relaxants while
  maintaining satisfactory intubation conditions
  seems to be rational approach but is also a
  challenge

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• French consensus conferences, anesthesiologists
  were free to use relaxant upon their judgement
• Patient characteristics and surgery types varied
  according to whether the patients received a
  relaxant or not
• Patients intubated without relaxants were younger
  and in better physical condition

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• Propofol ability to relax laryngeal muscles and
  to decrease upper airway reflexes
• Midazolam enhances propofol-related hypnosis
• Tracheal topical lidocaine reduces response to
  tracheal intubation
• This study simply is to observe and record
  current practice in the institution

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• Dose of propofol increase when relaxants were
  omitted ? raises the risk of dose-related side
  effects
• Propofol 3.4 mg/kg ? hypotension
• 3.1 mg/kg ? no hypotension
• High dose propofol/fentanyl ? significant
  hypotension
• Patients with induction-related-hypotension were
  older and had poorer ASA status
• Choice of sedation and muscular relaxation

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Intubating conditions

• Poor conditions 9 patients (1.6)
• Sustained cough is the main obstacle
• Several studies had frequency of 18
• Mecke and colleagues found poor intubation
  conditions in 1/3 patients intubated without
  relaxants

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• Difference in adverse conditions
• 1. Routine clinical practice ( propofol ?,
  topical anesthesia)
• 2. Relaxant group, intubating after complete
  abolition of response to TOF at adductor pollicis
• 3. Assured acceptable laryngoscopic conditions
  were present in all patients before intubation

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• Vocal cord sequela were more frequent when
  reaction to tube insertion or cuff inflation
  was not excellent (slight or sustained cough)
• Excellent conditions occurred less frequently
  when omitting relaxants (77 vs 93)
• If excellent intubation conditions are required,
  the use of muscle relaxants is mandatory
• Mencke and colleagues failed to demonstrate the
  difference between excellent and good intubating
  scores on postoperative laryngeal symptoms

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• The possibility to employ a relaxant-sparing
  approach to tracheal intubation without observing
  an increased incidence of poor intubating
  conditions or postoperative laryngeal symptoms
• Less excellent intubating conditions when
  omitting muscle relaxants
• If only excellent intubating conditions are
  acceptable, good clinical practice should
  recommend the use of relaxants
• On the contrary, if excellent or good intubating
  conditions are sufficient, then given the risks
  of using a relaxant, good clinical practice may
  permit less use of muscle relaxants