To the Editor:

We read with great interest the study by Ikeda et al.1  and the accompanying editorial.2  It is now increasingly recognized that muscle relaxants are beneficial in overcoming difficult mask ventilation in adults.2–4  However, both current papers are lacking a sufficient discussion of the reasons why muscle relaxation improves difficult mask ventilation. This can primarily be deduced from recent pediatric evidence where functional airway obstructions are the main reason for difficult mask ventilation.

Difficult mask ventilation in otherwise normal children is exceptionally rare and usually caused by anatomical/mechanical or functional airway obstructions.5  Functional airway obstructions (laryngospasm, insufficient depth of anesthesia, opioid-induced muscle rigidity with glottic closure, and bronchospasm) are common in children;6  result in significant morbidity;7  and require clear concepts and algorithms.8  Early muscle relaxation or even “pre-ventilation” muscle paralysis will overcome all functional airway problems with the exception of severe bronchospasm for which systemic epinephrine should be immediately available.9  This approach will also allow early and less traumatic direct laryngoscopy and tracheal intubation, if required urgently, without provoking coughing and straining or regurgitation and vomiting.

Amazingly, although muscle paralysis has been shown to improve mask ventilation in adults and is increasingly becoming a key role in the difficult mask ventilation in children with normal airways,9  none of current difficult airway algorithms in adults consider functional airway obstructions. However, this view is shifting in adults too, as the recently published NAP4 report recommends muscle paralysis prior to proceeding with an invasive (surgical) airway in the “cannot intubate - cannot ventilate” scenario or when waking the patient up is not an option.10 

Difficult mask ventilation due to functional airway obstruction with increasing hypoxemia requires muscle paralysis. “Cross the Rubicon fast” in patients with a normal airway.

Full report available at: http://www.rcoa.ac.uk/nap4. Accessed October 20, 2012.

References

1.
Ikeda
A
,
Isono
S
,
Sato
Y
,
Yogo
H
,
Sato
J
,
Ishikawa
T
,
Nishino
T
:
Effects of muscle relaxants on mask ventilation in anesthetized persons with normal upper airway anatomy.
Anesthesiology
2012
;
117
:
487
93
2.
Richardson
MG
,
Litman
RS
:
Ventilation before paralysis: Crossing the Rubicon, slowly.
Anesthesiology
2012
;
117
:
456
8
3.
Calder
I
,
Yentis
SM
:
Could ‘safe practice’ be compromising safe practice? Should anaesthetists have to demonstrate that face mask ventilation is possible before giving a neuromuscular blocker?
Anaesthesia
2008
;
63
:
113
5
4.
Kheterpal
S
,
Martin
L
,
Shanks
AM
,
Tremper
KK
:
Prediction and outcomes of impossible mask ventilation: A review of 50,000 anesthetics.
Anesthesiology
2009
;
110
:
891
7
5.
Tong
DC
,
Beus
J
,
Litman
RS
:
The Children’s Hospital of Philadelphia Difficult Intubation Registry.
Anesthesiology
2007
, pp
A1637
6.
Mamie
C
,
Habre
W
,
Delhumeau
C
,
Argiroffo
CB
,
Morabia
A
:
Incidence and risk factors of perioperative respiratory adverse events in children undergoing elective surgery.
Paediatr Anaesth
2004
;
14
:
218
24
7.
Bhananker
SM
,
Ramamoorthy
C
,
Geiduschek
JM
,
Posner
KL
,
Domino
KB
,
Haberkern
CM
,
Campos
JS
,
Morray
JP
:
Anesthesia-related cardiac arrest in children: Update from the Pediatric Perioperative Cardiac Arrest Registry.
Anesth Analg
2007
;
105
:
344
50
8.
Weiss
M
,
Engelhardt
T
:
Proposal for the management of the unexpected difficult pediatric airway.
Paediatr Anaesth
2010
;
20
:
454
64
9.
Engelhardt
T
,
Weiss
M
:
A child with a difficult airway: What do I do next?
Curr Opin Anaesthesiol
2012
;
25
:
326
32
10.
Woodall
NM
,
Cook
TM
:
National census of airway management techniques used for anaesthesia in the UK: First phase of the Fourth National Audit Project at the Royal College of Anaesthetists.
Br J Anaesth
2011
;
106
:
266
71