Securing a patent artificial airway in infants and children can be challenging, especially in preterm infants who are low or very low birthweight and/or when there is a need for an emergent intubation. In a letter to the Editor, Drs Bellini and Massirio emphasize the challenges clinicians have with initial placement of the endotracheal tube (ETT) in the mid-tracheal position. They also brought to light that the focus of the Kittredge Lecture paper1 was on oral intubation. Preferences for the route by which the trachea is intubated vary and may be dependent, as they point out, as a matter of training or clinician’s preference. The omission of nasal intubation as a focused area was not intended to minimize the importance of the use of this route. Rather, there was a focus on the most commonly used method of intubating the trachea by respiratory therapists. It is, however, important to note that the choice to intubate the trachea nasally or orally can also be influenced by the urgency with which an artificial airway and ventilatory assistance is needed. Oral intubation can be accomplished in less time,2 is associated with a higher first-time success rate,3 and is the preferred route when the airway needs secured emergently.4
Drs Bellini and Massirio also highlight the challenges clinicians are faced with when trying to accurately predict ETT insertion depth. They eloquently reemphasized the inaccuracies that occur with using weight-based formulas from the current neonatal resuscitation program (NRP)5 and former pediatric advanced life support (PALS)6 guidelines (for infants < 1 y of age) to predict correct ETT insertion depth. They also provided additional support for the shortcomings of common simple formulas that are simple to memorize and use internal diameter (ID) of ETT as a predictor of depth (3 × ID of the ETT in mm),7 have limited utility, and exclude ETTs with ID < 3.0 mm.
From a clinical practice perspective, our own experience with the use of NRP and PALS guidelines to predict ETT insertion depth exemplifies the issues Drs Bellini and Massirio highlight in their letter. This single institutional retrospective study included infants and children with whom the first chest radiograph was obtained after intubation in the operating room, emergency department, pediatric ICU, or during interfacility transport.8 There was a very high rate of improperly placed ETTs (malposition) in 69% or 330 of the 477 subjects when PALS6 or NRP5 guidelines were used to predict ETT insertion depth.8 Use of the NRP and PALS guidelines to determine the initial ETT insertion depth resulted in an initial placement that was too deep.8 A majority (88%, n = 291) of malpositioned ETTs resulted in an endobronchial intubation or an ETT that was < 1 cm from the carina.8 Given the relatively short length of the trachea, especially in preterm infants, there is little tolerance for error.
Shortcomings of currently available validated prediction formulas inspired researchers to explore modifications to the formula provided in the NRP guidelines,5 originally based on Tochen’s9 work. Bartle and colleagues10 evaluated the predictive value of a modification of the depth guidelines endorsed by NRP in a cohort of 131 preterm infants weighing < 1 kg. The use of the modified formulas, 5.0 cm + 1 cm/kg for preterm infants weighing < 500 g and 5.5 cm +1 cm/kg for preterm infants weighing between 500–999 g, accurately predicted ETT tip position in 47% of those studied. Sensitivity 46.6%, specificity 53.6%, and positive predictive value 68.8% were reported. Post hoc analysis revealed these formula modifications provided a closer approximation of actual ETT depth (47%) compared to NRP guidelines (23%).10 Similarly, in a cohort of 75 preterm infants weighing 410–990 g, Bellini and colleagues11 evaluated a modification of the formula recommended by NRP, reported as the Genoa formula (ETT depth [cm] = 2 × weight [kg] + 5.5 cm), to determine the initial insertion depth for preterm infants whose ETT was inserted nasally. The researchers reported good correlation with birthweight (R2 = 0.491) and initial insertion of the ETT in the mid-tracheal position.11 The results of these studies are encouraging and provide clinicians with potential alternatives that encompass both oral and nasal intubation routes. However, it is important to recognize the shortcomings of single-institution retrospective studies with a small number of subjects. As with Bartle’spredictive equation, the equation that Bellini and colleagues propose requires prospective evaluation with a larger, more diverse population to externally validate their clinical utility.
Footnotes
- Correspondence: Teresa A Volsko MBA MHHS RRT FAARC, Quality and Data Integration, The Centers, 3500 Euclid Avenue, Cleveland, Ohio 44103. E-mail: teresa.volsko{at}thecentersohio.org.
Ms Volsko has disclosed relationships with FirstEnergy, Actuated Medical, and Neotech.
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