Stridor is not a scientifically valid outcome measure for assessing airway injury

Abstract

SummarySince about a decade cuffed intubation is becoming more popular in pediatric anesthesia. Studies supporting cuffed intubation compared cuffed and uncuffed intubation by using stridor as main outcome measure after extubation. No differentiations were made between benign (oedema) and severe (ulceration of mucosa) lesions. Stridor was considered to represent all relevant injuries. Far reaching conclusions for daily practice were drawn from these studies. Pediatric endoscopists and -ENT-surgeons with extensive experience in this field have warned against this opinion because significant injury of the airway is not always accompanied by stridor! The symptom of stridor might develop weeks and months after injury when silent ulcerations of the mucosa retract to significant stenosis. Only endoscopy can evidently detect all airway injuries. Studies describing airway injury by endoscopic control are urgently needed to find the best way of preventing airway injury by intubation.

Extubation Failure after Neonatal Cardiac Surgery: A Multicenter Analysis

“…Stridor was only noted in two patients who failed extubation, but significant injury to the upper airway is not always accompanied by stridor [24]. Indeed, in neonates, small decreases in airway diameter from airway edema or inflammation may not cause overt stridor but could markedly increase airway resistance, which is proportional to radius to the fourth power [8].…”

Intubation of the Pediatric Patient

“…Another reason for conflicting arguments might be the inadequate knowledge of the intricate anatomy of the pediatric larynx by many anesthesiologists, as proven in clinical practice [7,8]. This can also be observed in many discussions during workshops where a common teaching is: ''aim with the tip of the tube at the dark triangle between the vocal cords and push the tracheal tube into it and you are safe''.…”

“…Particularly ulcers after extubation are frequently overlooked since they never produce the symptom of stridor which needs an obstruction of more than 50 % of the lumen to become audible. Therefore stridor is an entirely insufficient outcome measure in studies which are investigating airway trauma [8]. However, ulcers may become infected and cause airway obstruction weeks or months after intubation when nobody thinks of a relation to the intubation.…”

“…However, to visualize the larynx below the vocal cords and the advancement of the tracheal tube beyond the glottis, a small Hopkins rod lens (Fig. 6.2) is necessary to document injuries or malformations in this area [7,8]. In case of suspecting an injury, the mucosa of the upper airway can be controlled during and immediately after extubation.…”

“…Handhold with battery The endoscopic experience of decades of pediatric intubation of the author of this chapter and his group [7,8] has proven over the past 35 years that a curved blade with a pronounced bending of the tip (30-40°), placed into the vallecula, provides the best general view of the entrance of the larynx. This almost wide angled view offers a good chance for placing a tracheal tube through the larynx into the trachea of infants and children in the least traumatic way (see Fig.…”