SCCM Resource Library-31-Impact of Cuffed Endotracheal Tube Size on Post-Extubation Upper Airway Obstruction in Infants

Video Transcription

My name is Deirdre Lewis, I'm a current Pediatric Critical Care Fellow at Cohen Children's Medical Center in New Hyde Park, New York, and I'm here today to discuss our project,  the impact of cuffed endotracheal tube size on post-extubation strider in infants. I have no conflicts of interest to disclose.  Beginning with a little bit of background, cuffed endotracheal tubes are often selected based on the modified Cole formula, H over 4 plus 3.5.  However, there's some ambiguity in this formula, as it often requires some rounding. For example, the one-year-old patient would call for a 3.75 cuffed endotracheal tube size,  therefore the provider must choose between a 3.5 and a 4.0. Oversized endotracheal tubes may put patients at risk for upper airway obstruction and post-extubation strider.  This is particularly true in infants, as high rates of post-extubation upper airway obstruction  have been demonstrated in this age group, with the incidence varying from 3.5% to 30.2% in the literature.  In addition, a large percentage of pediatric ICU patients are infants, therefore correct  endotracheal tube size selection has important implications in the quality of care of a large portion of PICU patients.  In one study, up to 27% of pediatric ICU admissions were patients less than 365 days. Finally, a review of endotracheal tube sizes placed in infants in our PICU revealed clinical  equipoise between 3.5 and 4.0 endotracheal tubes, prompting us to question what the best size may be.  This led us to hypothesize the following, 4.0 cuffed endotracheal tubes are associated with higher rates of post-extubation strider than 3.5 or 3.0 cuffed endotracheal tubes  in infants less than 365 days correct to gestational age. Moving into our study design, we designed this as a single center retrospective chart  review at a tertiary care pediatric ICU. We intentionally excluded the neonatal ICU from our analysis because of the differing  practice patterns between the two units, including differences in cuffed versus uncuffed endotracheal  tube, differing sedation practices, and differing protocols regarding extubation readiness. For inclusion criteria, we included patients who were intubated at less than 365 days  correct to gestational age, who were also extubated during their pediatric ICU admission. We excluded patients who were intubated for greater than 24 hours at an outside hospital,  who were intubated with an uncuffed endotracheal tube, or who either expired on the ventilator  or required tracheostomy, implying they didn't have a true extubation during their ICU stay.  For a primary outcome, we defined post-extubation stridor as the use of racemic epinephrine within six hours of extubation.  This was a purely pragmatic decision based on the limitations of our electronic medical record.  Whereas the clinical finding of stridor could be incompletely or inconsistently documented, the ordering of racemic epinephrine was a great objective marker for what was going  on at the bedside. Moving on to what variables we collected, here's a table showing that. We abstracted the charts for age, prematurity, height and weight, history of GERD, history  of known abnormal upper airway, intubation indication, which I'll come back to, endotracheal  tube size, duration of mechanical ventilation, pre-extubation leak, pre-extubation decadron,  post-extubation therapies for stridor, including racemic epinephrine, and re-intubation rates. Regarding intubation indication, we broke this down into elective versus non-elective.  Elective intubation was done under controlled circumstances, such as going to the operating room or being intubated for a procedure.  Non-elective intubation was done under emerging conditions, including situations such as being intubated for airway protection in status epilepticus, for acute respiratory failure,  or for a code situation. Moving into our results, here in this table we show a distribution of endotracheal tube size in our cohort.  Along the bottom you'll see totals, including our total N, which was 356 charts. You can see that most of our patients were intubated with 3-5 tubes, with a large minority  receiving 4-0 tubes, and relatively few 3-0 tubes. We then broke the cohort down into 0-180 days corrected gestational age, and 181-365 days corrected gestational age.  And when we did that, an interesting trend emerged. In the younger cohort, the majority of patients were intubated with 3-5 cuffed endotracheal  tubes, with relatively few 4-0 and 3-0 tubes. However, this trend changed as patients aged, emerging into a near 50-50 split between 3-5  and 4-0 cuffed endotracheal tubes, and virtually no 3-0 tubes. This suggested to us that as patients aged and became larger, providers felt more comfortable  placing 4-0 cuffed endotracheal tubes.  And in fact, this turned into a statistically significant finding, where patients aged 181-365  days corrected gestational age were more likely to be intubated with 4-0 cuffed endotracheal tube than a 3-5 cuffed endotracheal tube, compared to patients aged 0-180 days corrected  gestational age. And this had a p-value of less than 0.001.  Moving on to look at rates of post-extubation stridor. First, we wanted to compare 3-5 versus 3-0 cuffed endotracheal tubes.  Here in this table, we see our rates of post-extubation stridor in each of these groups, with 5 out  of 22 patients intubated with 3-0 tube having post-extubation stridor, and 54 out of 257 patients with a 3-5 tube having post-extubation stridor.  This led to an odds ratio for post-extubation stridor of 0.90, with a p-value of 0.85, which did not meet statistical significance.  Whether or not we did not meet significance because there's truly no difference between 3-5 and 3-0 cuffed endotracheal tubes, in terms of their effects on post-extubation  stridor, or we did not meet significance because there were relatively few 3-0 cuffed endotracheal tubes in our cohort, was a little unclear to us.  Moving on, I'd now like to discuss our rates of post-extubation stridor in 4-0 versus 3-5 cuffed endotracheal tubes. And here we did find some statistically significant findings.  In this first line, we're looking at the total, and we see 54 out of 257 patients with 3-5 cuffed tubes had post-extubation stridor, as opposed to 29 out of 77 patients with a  4-0 tube. This led to an odds ratio of 2.27, with a p-value of 0.035, suggesting that a 4-0 tube increased your odds of post-extubation stridor.  When we broke the cohort down into the age groups again, 0 to 180 days versus 181 to 365 days, this finding remained statistically significant.  In the younger group, 50 out of 209 patients with a 3-5 cuffed endotracheal tube had post-extubation  stridor, as opposed to 11 out of 27 in the 4-0 cuffed endotracheal tube group, for an odds ratio of 2.19 and a p-value of 0.065.  What was really striking to us was when we looked at the older age group, 181 to 365 days, the odds ratio was even higher at 6.19, with 4 out of 48 patients with 3-5 tubes  having post-extubation stridor, and 18 out of 50 patients with a 4-0 tube having post-extubation stridor.  This p-value was highly significant at 0.002, suggesting that this 4-0 tube in this particular age group really does increase your odds of post-extubation stridor.  If you'll recall from our slide regarding the distribution of endotracheal tubes, this age group also has a much higher rate of 4-0 tubes being placed, because perhaps providers  perceive that these patients are larger, and that's the more appropriately sized tube. Moving on from our univariate analysis to our multivariate analysis, when constructing  our model, we chose to include variables that had a p-value of less than 0.2. Among those variables that we collected, the ones that met criteria for inclusion were  intubation indication, endotracheal tube size, and pre-extubation decadron. This is what we found.  Endotracheal tube size, when controlling for elective intubation and decadron prior to extubation, remained statistically significant, I should say, with an adjusted odds ratio  of 1.79 and a p-value of 0.018, suggesting once again that the bigger your tube, the higher your odds of post-extubation stridor.  Elective intubation had an adjusted odds ratio of 0.37, with a p-value of less than 0.001, which is saying that if you were intubated electively, you had a lower odds of having  post-extubation stridor, and the reverse being true. If you were intubated non-electively, your odds of post-extubation stridor went up.  Finally, decadron prior to extubation had an adjusted odds ratio of 1.61, but did not meet statistical significance with a p-value of 0.087. However, it was verging on significance.  What was interesting to us about this finding is you would expect the reverse to be true. What this is saying is that if you received decadron prior to extubation, your odds of  post-extubation stridor go up, though not in a statistically significant manner. However, what this may suggest is that decadron is something that the provider has to decide  to give to the patient. So perhaps there was something about the patient, such as the absence of a leak, that  was pushing the providers into giving decadron, and it's those other factors that are actually predictive of the post-extubation stridor.  So, tying it all together with some conclusions. Once again, a large percentage of pediatric ICU patients are infants, and correct endotracheal  tube size selection has important implications in the quality of their care.  This retrospective single-center chart review study of patients intubated at less than 365 days correct to gestational age showed that 4.0 cuffed endotracheal tubes are associated  with an increased odds ratio of post-extubation stridor. And it also showed that providers are more likely to place these tubes in older infants.  Upon multivariate logistic regression, cuffed endotracheal tube size remained significant after controlling for intubation indication and pre-extubation steroid use.  Taking all these findings together, should you find yourself in a situation where you were deciding between a 3.5 and a 4.0 cuffed endotracheal tube in an infant, I would suggest  placing a 3.5 cuffed tube, as it may decrease your association with post-extubation stridor,  unless you have a compelling alternative indication to place a 4.0 cuffed endotracheal tube. Thank you, and I'll now take any questions.

Video Summary

The impact of cuffed endotracheal tube size on post-extubation stridor in infants was examined in a single-center retrospective chart review study. The study found that using a 4.0 cuffed endotracheal tube increased the odds of post-extubation stridor compared to a 3.5 tube. This finding was especially significant in infants aged 181 to 365 days. Providers tended to place larger tubes as infants aged. The study suggests that using a 3.5 cuffed tube may decrease the risk of post-extubation stridor in infants, unless there is a specific reason to use a larger tube. The results have important implications for the quality of care for infants in pediatric ICUs.

Asset Subtitle

Pediatrics, Pulmonary, 2021

Asset Caption

The Society of Critical Care Medicine's Critical Care Congress features internationally renowned faculty and content sessions highlighting the most up-to-date, evidence-based developments in critical care medicine. This is a presentation from the 2021 Critical Care Congress held virtually from January 31-February 12, 2021.

Deirdre Lewis

Introduction/Hypothesis: Infants comprise a relatively large proportion of PICU admissions. There are no standardized guidelines for selection of cuffed endotracheal tube (ETT) size in this age group, though the modified Cole formula is frequently used. Upper airway obstruction (UAO) after extubation is a common problem. The purpose of this study was to assess the relationship of ETT size to post-extubation UAO in infants in the PICU.

Methods: This was a single-center retrospective chart review of patients <1 year corrected gestational age (CGA) admitted to the PICU at a pediatric tertiary care center between 2013-2020. Patients were included if their first intubation during a hospital admission was with a cuffed ETT. The outcome of interest was UAO, defined as the need for racemic epinephrine (RE) within 12 hours post-extubation. Only the first intubation per admission was considered. Univariate and multivariate analyses were performed.

Results: 356 charts met inclusion criteria. 22 (6.2%) patients received a 3.0 cuffed ETT, 275 (77.2%) received a 3.5 cuffed ETT, and 77 (21.6%) received a 4.0 cuffed ETT. Patients with CGA 181-365 days were more likely to be intubated with a 4.0 than 3.5 ETT compared to patients with CGA 0-180 days (51.0% vs. 11.4%, p<0.001). 88 (24.7%) patients in the whole cohort required RE post-extubation. Patients intubated with a 4.0 cuffed ETT compared to 3.5 cuffed ETT were more likely to require RE, with an OR of 2.27 [1.31-3.94] (p=0.035) for the whole cohort, an OR of 2.19 [0.95-5.02] (p=0.065) for CGA â‰¤180 days, and an OR of 6.19 [1.91-20.04] (p=0.002) for CGA 180-365 days. There was no difference in RE use in 3.0 vs. 3.5 cuffed ETT in either whole group (OR=0.90 p=0.85) or subgroup analysis. A multivariate logistic regression model was constructed using variables with p<0.20 in the univariate analysis; cuffed ETT size remained significant after controlling for intubation indication and pre-extubation steroid use.

Conclusions: Older infants were more likely to have 4.0 than 3.5 cuffed ETTs placed, but subgroup and whole cohort analysis showed that 4.0 cuffed ETTs were consistently associated with higher rates of RE use post-extubation. As infants comprise a large proportion of PICU admissions, these results are important for assisting pediatric intensivists in cuffed ETT size selection.

Meta Tag

Content Type Presentation

Knowledge Area Pediatrics

Knowledge Area Pulmonary

Knowledge Level Intermediate

Knowledge Level Advanced

Membership Level Select

Tag Extubation

Tag Airway Management

Year 2021

Keywords

cuffed endotracheal tube size

post-extubation stridor

infants

retrospective chart review study

pediatric ICUs

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