Epistaxis is a common and sometimes serious risk associated with nasotracheal intubation. In this study, we found that the use of a Parker Flex-Tip nasal ETT did not provide a significant reduction in the incidence or severity of epistaxis when compared with a conventional nasal RAE ETT. These findings contrast with previous studies by Sanuki et al. and Sugiyama et al. who found that the absolute risk of epistaxis was reduced by 24% and 26%, respectively, with the PFT vs a standard nasal RAE ETT.7,8 Thermosoftening the ETT was part of our protocol, as previous studies have found that it leads to a reduction in epistaxis, and moreover, it is the usual practice in our institution.6,10 Since thermosoftening was absent in the Sugiyama and Sanuki studies,7,8 it raises the question whether this practice negated any of the previously found superiority of the PFT. This might warrant further investigation. It is also possible that our results are subject to the Hawthorne effect, i.e., due to their awareness of the study, the attending anesthesiologists may have altered their behaviour by performing the intubations more cautiously. Nevertheless, this would likely affect both groups equally, changing the overall epistaxis rates but still allowing for differences between them to remain evident. Furthermore, it is possible that the intubating anesthesiologist was biased towards either the standard ETT or the more novel PFT ETT, as they were not blinded to tube selection during intubation.
Importantly, the overall epistaxis rate in our control group (70%) was higher than reported in previous studies (35.3-50%).7,8 This difference could be due to different operator practice or increased heterogeneity of our patient characteristics given our multiethnic population (both comparative studies were based in Japan). Nevertheless, if these factors were influencing epistaxis rates, one would still expect to discern a difference between the two ETTs if the PFT was superior to the standard ETT. Another possible explanation could be that Sanuki potentially underestimated the epistaxis rates. Sanuki examined the oropharynx immediately after intubation, whereas we allowed a five-minute transit time for blood to reach the oropharynx.8 While Sugiyama did report measuring epistaxis at one and five minutes, only overall rates of bleeding were reported with no comparison between the two time points.7 Another explanation could be the size of ETT used in the Sugiyama (7.0 and 7.5) and Sanuki (7.0) studies, which were larger than the ETTs used (6.0-7.0) in our study.7,8 Although a smaller ETT size may potentially cause less trauma, the larger diameter may better tamponade any bleeding of the mucosal tissue. This warrants further investigation.
Importantly, as the PFT is considerably more expensive (approx. $14.15) than the standard nasal RAE ETT (approx. $5.35), the lack of specific clinical benefit (i.e., reduced epistaxis rate) would make the additional cost difficult to justify.
There are several limitations to our study that should be considered. First, in order to blind the independent investigator to ETT type, the proximal end and balloon port were covered and the distal tip was obscured past the cords. Nevertheless, the central portion of the ETT was visible during laryngoscopy and very minor differences in tube appearance may have been distinguishable. Unfortunately, this was unavoidable as it was not possible to assess for epistaxis adequately with the entirety of the ETT obscured. Guidelines to assess bleeding rates were very clearly defined in order to make the epistaxis assessment as objective as possible. Second, as mentioned above, epistaxis was assessed five minutes post intubation but not after extubation or at any time point postoperatively. It is possible that bleeding may have occurred after removal of the ETT due to removal of a tamponade effect or trauma during extubation. Nevertheless, after extubation, it would be difficult to differentiate surgical bleeding, particularly given the variable maxillofacial surgeries of our patient population. Furthermore, it would be challenging clinically to obtain an adequate view of the posterior pharynx with direct laryngoscopy once the patient underwent tracheal extubation and emerged from anesthesia. Lastly, epistaxis rates were not recorded based on the allocation of the various attending anesthesiologists to the different study groups, which may present a variable that was not accounted for our in our data.
In conclusion, we found that the PFT nasal ETT did not result in a significant reduction in epistaxis during nasal intubation when compared with a standard nasal RAE ETT in our patient population. Further studies are recommended to determine how thermosoftening may affect previously reported reductions in epistaxis rates and to assess the effect of ETT size on epistaxis rates following extubation.