We were interested in the recent study by Watt et al
to reduce epistaxis during nasotracheal intubation in children by telescoping the tip of the endotracheal tube into the funnel end of the red rubber urethral catheter. However, we have a few points to make.
The results of using a prewarmed tube for nasotracheal intubation are variable.1–3
Although studies in adults suggest reduced bleeding, its efficacy in pediatric patients seems to be poor.1–4
In the control group in the study by Watt et al
where tracheal intubation was achieved by using a tube at room temperature, the incidence of bleeding was 56%, significantly higher than in the control group of Elwood et al
wherein a thermosoftened tube was used and the incidence of bleeding was only 29%. Further, although Watt et al
report that a 39% incidence of epistaxis in patients in whom the nasotracheal tube was carried with a thermosoftened uncuffed tube is consistent with that reported by Elwood et al
in their thermosoftening group (29%), it is still higher in the study of Watt et al
. Considering these facts, in the study by Watt et al
., the higher incidence of bleeding in patients in whom a prewarmed tube was used can be attributed to the use of a larger tube (selected by Cole’s formula, i.e
., ID (mm) = (age/4) + 4) rather than lack of efficacy of thermosoftening and topical vasoconstriction, especially when no direct comparison of epistaxis, with and without a nasal topical vasoconstrictor, was made by the authors. For nasotracheal intubation, it is strongly recommended to use an endotracheal tube with an ID 0.5–1.0 mm less than that used for an oral tube, to allow for smooth and atraumatic passage of the nasal tube.5
This is evident in various adult and pediatric studies of nasotracheal intubation. Elwood et al
. selected the uncuffed tube for nasotracheal intubation by the formula of Motoyama6
., ID (mm) = (age/4) + 3.5) and, as aforementioned, had better results in the thermosoftening group than achieved by Watt et al
., who used endotracheal tubes at room temperature and after thermosoftening.4,7,8
Although we wholeheartedly agree with Watt et al
.’s report of better results than Elwood et al
. in regard to clinically relevant bleeding (5% vs
. 9.4%) in patients in whom a red rubber catheter was used, we believe that selection of the tube by the formula of Motoyama or Khine (i.e
., ID (mm) = (age/4) + 3.0) by Watt et al
. could have further reduced the incidence of clinically significant nasal bleeding in all three groups.5,6
Regarding the intubation attempts, Watt et al
. did not mention the number of times each naris was entered or the navigability (smooth or impinged) of the endotracheal tube. No data were provided regarding postoperative nasal complications such as nasal pain, persistent discharge or bleeding, difficult breathing, or crusting, which are important secondary outcomes in patients undergoing nasotracheal intubation and are likely to be significantly affected by the size of tube used, thermosoftening, and whether topical nasal vasoconstrictor drops were used.5,7,8
Including these sequelae in their trial could have better delineated the role of the vasoconstrictor in delayed outcomes of pediatric nasotracheal intubation.
Rahul Gupta, M.D.
Anju Sharma, M.B.B.S.
*Acharya Shri Chander College of Medical Sciences, Jammu, India. email@example.com