Respiratory Complications Between Cuffed and Uncuffed Endotracheal Tubes in Pediatric Respiratory Management After Palatoplasty: Single-Center Retrospective Cohort Study

OBJECTIVES:

We aimed to examine the associations between use of cuffed or uncuffed endotracheal tubes (ETTs) and complications during and after short-term intubation of post-palatoplasty patients without intrinsic lung disease.

DESIGN:

Retrospective cohort study.

SETTING:

Operating room and PICU.

PATIENTS:

Children without intrinsic lung disease who had undergone palatoplasty at a single institution. Inclusion criteria: intubation using ETTs with an internal diameter of 3.5 mm and postoperative management in the PICU. Exclusion criteria: 1) patients for whom ETTs with internal diameters other than 3.5 mm were used, 2) patients who had already been extubated in the operating room, and 3) patients who had a tracheostomy.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

Eighty-seven patients were screened for eligibility; 71 met the inclusion criteria. Of the 71 patients, 41 (58%) with polyurethane-cuffed ETTs (PUC-ETTs) and 30 (42%) with uncuffed ETTs were enrolled. We failed to identify an association between type of PUC-ETT and the development of atelectasis (odds ratio [OR], 1.06; 95% CI, 0.35–3.20; p = 1.00). Similarly, we failed to identify an association between type of PUC-ETT and development of stridor (OR, 1.58; 95% CI, 0.43–5.81; p = 0.715) or hoarseness after extubation (OR, 7.03; 95% CI, 0.83–59.6; p = 0.10). At extubation, air leak pressure was higher in the PUC-ETT group than in the uncuffed ETT group (p < 0.001), a finding which was not evident at intubation. The number of patients who received IV dexamethasone and the cases of inhaled racemic epinephrine were not statistically significant.

CONCLUSIONS:

In this select population of post-palatoplasty infants without intrinsic lung disease, we failed to identify any association between type of ETT (cuffed or uncuffed) and greater odds of developing respiratory complications. Taken together with the 95% CI of the effect size, our data indicate continued uncertainty about type of ETT that should be used for short-term intubation.

KEY POINTS

Question: The associations between the use of cuffed or uncuffed endotracheal tubes (ETTs) and the difference in complications during and after short-term intubation without intrinsic lung disease is still unknown.

Findings: The population in this study was very specific to post-palatoplasty infants without intrinsic lung disease and therefore the results are not widely generalizable. However, we failed to identify any association between type of ETT and greater odds of respiratory complications.

Meanings: The results imply no preference in type of ETT in this population.

In pediatric airway management, uncuffed endotracheal tubes (ETTs) are conventionally used to treat airway mucosal injury. Because of the elliptical shape of the pediatric tracheal anatomy, cuffed ETTs are considered to induce airway damage (1, 2). However, the development of polyurethane-cuffed ETTs (PUC-ETTs) designed specifically for the pediatric anatomy has encouraged the use of cuffed ETTs in pediatric airway management (3). Recent clinical studies have suggested that PUC-ETTs can be used to decrease the leakage of pharyngeal secretions into the trachea. Several studies in adults have also reported that the use of PUC-ETTs can reduce the prevalence of ventilator-associated pneumonia in comparison with polyvinyl chloride-cuffed ETTs (PVC-ETTs) (4–6). In pediatric respiratory management, a few studies have compared the atelectasis-associated complications of PUC-ETTs and conventional uncuffed ETTs. These studies revealed opposite results about the association between cuffed ETT or uncuffed ETT and atelectasis (7, 8). Whether the frequency of atelectasis in the PUC-ETT group is lower than that in the uncuffed ETT group is still controversial. Several studies have shown no association between the use of either cuffed or uncuffed tubes and the occurrence of acute respiratory complications after extubation, indicating that cuffed and uncuffed tubes are equally safe to use in children (7). This study aimed to compare the associations between type of ETT used (cuffed or uncuffed) with an internal diameter of 3.5 mm and development of respiratory complications during and after short-term intubation of post-palatoplasty patients without intrinsic lung disease. Specific population of post-palatoplasty patients is at high risk of postoperative airway and respiratory complications because of the surgical wound site (9). It is therefore important to investigate the complications.

MATERIALS AND METHODS

Study Design and Patients

This retrospective cohort study was approved by Institutional Review Board (IRB) at Nagano Children’s Hospital (approval number: 30-24, approval date: June 20, 2018). Procedures were followed in accordance with the ethical standards of the IRB on human experimentation and with the Helsinki Declaration of 1975. This study aimed to identify the prevalence of acute respiratory complications during and after intubation. No written consent was required because of the observational nature of the study. The patients were children without intrinsic lung disease who had undergone palatoplasty at our institution between January 2014 and December 2018. The inclusion criteria were intubation using ETTs with an internal diameter of 3.5 mm, and postoperative management in the PICU. We excluded the following patients: 1) patients for whom ETTs with internal diameters other than 3.5 mm were used, 2) patients who had already been extubated in the operating room, and 3) patients who had a tracheostomy.

The patients were divided into two groups based on use of cuffed or uncuffed ETTs. Demographic data such as sex, age (mo), weight, height, number of congenital deformities related to the upper airway, tube exchange, Cormack-Lehane classification (which indicates difficult intubation), diagnosis (type of cleft palate), surgical procedure, total fluid intake per body weight during intubation, percentages of procedures, and anesthesia, procedure, and intubation durations were compared.

Anesthetic and Surgical Procedures

Anesthesia during surgery was managed according to the guidelines in our anesthesia department. Throughout the operation, inhaled sevoflurane or IV propofol was used for sedation; IV fentanyl boluses or continuous IV remifentanil was used for analgesia; and rocuronium was used as a muscle relaxant. The surgical procedure consisted of pushback palatoplasty, two-flap palatoplasty, or intravelar veloplasty, during which the Dingman mouth gag was used and relaxed every 60 minutes.

Tracheal Intubation Strategy

The patients received PUC-ETTs (Microcuff; Halyard Healthcare, Alpharetta, GA) or uncuffed ETTs (Portex; Smiths Medical, Plymouth, MN). According to our institutional guidelines for palatoplasty, ETT internal diameter size was usually selected as follows: cuffed ETT, 3.5 + age/4 (mm); uncuffed ETT, 3.5 + age/4 (mm). While both of these tubes had an inner diameter of 3.5 mm, Microcuff has an outer diameter of 5.0 mm, and Portex has an outer diameter of 4.8 mm. Tracheal intubation was performed using direct laryngoscopy or monitor-integrated video laryngoscopy via the oral route. The ETT insertion depth was based on the local guidelines in our anesthesia department. We then checked for audible air leaks near the patient’s mouth. In cases with an unsuitable large air leak or no audible air leak, we performed a tube exchange. In cases using the PUC-ETT, the inflation cuff pressure was adjusted to 20 cm H₂O. During our study period, surgical procedures were selected and performed by two attending plastic surgeons (A or B) because one attending surgeon (A) resigned from our hospital in 2018.

Postoperative Care in PICU

After palatoplasty, all patients were transferred back to the PICU and were mechanically ventilated in the pressure control mode. In the PICU, we continued to provide the patients with continuous IV sedation (midazolam), analgesia (fentanyl), and muscle relaxants (rocuronium) throughout their mechanical ventilation. Intensivists checked whether each ETT was located in the trachea above the carina in each chest radiograph and made adjustments, if necessary, as part of routine care. In the PUC-ETT group, inflation cuff pressure was measured and maintained at 20 cm H₂O immediately upon arrival at the PICU. The inflation cuff pressure was adjusted to 20 cm H₂O every 6 hours as a standard protocol in our unit. IV fluid administration was performed for all patients. The amount of fluid intake until extubation was calculated as 80% of the maintenance fluid requirement based on the Holliday-Segar method.

On the first day after surgery, if the surgeon judged that the wound had no problem, we stopped providing continuous IV sedation, analgesia, and muscle relaxants and administered sugammadex sodium. Subsequently, the patients were extubated when they recovered adequate spontaneous respiration and consciousness. Before extubation, the cuff was fully deflated, and checks for audible air leaks near the patient’s mouth were conducted, similar to those performed just after intubation. If no audible air leak was confirmed, the patients were administered IV dexamethasone before extubation as a standard protocol in our unit. After extubation, the patients with stridor or hoarseness were provided with inhaled racemic epinephrine based on the subjective judgment of the clinicians.

Screening and Diagnosis

Between the PUC-ETT and uncuffed ETT groups, we compared the frequency of atelectasis during intubation, the incidence of stridor and hoarseness after extubation, air leakage pressure after intubation and before extubation, the number of patients who received IV dexamethasone, and the cases of inhaled racemic epinephrine. Atelectasis was defined as an opacification on the chest radiograph with loss of lung volume and detected daily in each chest radiograph by radiologists at our institution. The existence of atelectasis was also confirmed by the authors retrospectively. Stridor was defined as a high-pitched inspiratory sound after extubation, as described in the medical records. Hoarseness was confirmed based on the medical records, as described subjectively by clinicians. Air leakage pressure near the patient’s mouth was confirmed based on the medical records described at the time of intubation and extubation. The number of patients who received IV dexamethasone and inhaled racemic epinephrine were also detected retrospectively from the medical records.

Statistical Analysis

No statistical sample size calculations were conducted. Quantitative variables were reported as mean ± sd or median and interquartile range and were compared using the Mann-Whitney U test. Qualitative variables were reported as percentages and compared using chi-square analysis. Binary outcomes are presented as odds ratio (OR) with 95% CI. Statistical significance was set at p value of less than 0.05. Statistical analyses were performed using Easy R (EZR) version 1.33 (Jichi Medical University Saitama Medical Center, Saitama, Japan), which is based on the R open-source software and R commander (10, 11).

RESULTS

Characteristics of Eligible Patients

A total of 87 patients were screened for eligibility, and 71 met the criteria. Of the 71 patients, 41 (58%) with PUC-ETTs and 30 (42%) with uncuffed ETTs were enrolled (Fig. 1). The two groups showed no significant differences in terms of sex, age (mo), weight, height, number of congenital deformities related to the upper airway, tube exchange, Cormack-Lehane classification, diagnosis (type of cleft palate), surgical procedure, and total fluid intake per body weight during intubation. There was a significant difference in the types of procedures performed between both groups. Anesthesia, procedure, and intubation durations were significantly longer in the PUC-ETT group than in the uncuffed ETT group (Table 1). Six patients with PUC-ETT had a delay in extubation, due to no audible air leakage in five cases and postoperative oral hemorrhage in one case. These patients were successfully extubated on postoperative day 2. The list of congenital deformities related to the upper airway is shown in Table 2.

Figure 1.

Diagram shows the flow of participants of this study. ETT = endotracheal tube, OR = operation room.

TABLE 1.

Baseline Characteristics of the Patients Included in the Study Variables

Variables	Polyurethane-Cuffed ETT	Uncuffed ETT	p
Patients, n (%)	41 (58)	30 (42)	—
Male, n (%)	18 (44)	14 (47)	1.0
Age, mean (IQR), mo	15.0 (14.0–17.0)	15.0 (14.0–15.8)	0.567
Weight, mean ± sd, kg	9.6 ± 1.2	9.3 ± 1.0	0.24
Height, mean ± sd, cm	75.9 ± 3.4	75.4 ± 2.4	0.471
Congenital deformities, n (%)	6 (15)	8 (27)	0.239
Tube exchange, n (%)	1 (2)	2 (7)	0.488
Cormack-Lehane classification, n (%)			1.0
1	34 (83)	27 (90)
2	3 (7)	3 (10)
3	1 (2)	0
4	0	0
Operator, n (%)			< 0.001
A	24 (59)	29 (97)
B	17 (42)	1 (3)
Diagnosis, n (%)			0.96
Cleft palate and lip
Bilateral	7 (17)	5 (17)
Unilateral	15 (37)	12 (40)
Isolated cleft palate	11 (27)	6 (20)
Submucous cleft palate	2 (5)	1 (3)
Soft cleft palate	6 (15)	6 (20)
Type of surgical procedure, n (%)
Push back	1 (2)	6 (20)	0.037
Two flap	40 (98)	16 (53)	< 0.001
Intravelar veloplasty	21 (51)	10 (33)	0.153
Anesthesia duration, mean (IQR), min	262 (246–292)	243 (221–270)	0.049
Procedure duration, mean (IQR), min	225 (196–259)	199 (167–243)	0.043
Intubation durations, mean (IQR), min	1,365 (1,293–1,417)	1,244 (1,209–1,281)	< 0.001
Postoperative day to extubation, n (%)			0.091
Day 1	35 (85)	30 (100)
Day 2	6 (15)	0
Fluid intake per body weight, mean (IQR)	37.6 (23.9–44.4)	35.3 (28.4–41.7)	0.623

ETT = endotracheal tube, IQR = interquartile range.

TABLE 2.

List of Congenital Deformities Related to Upper Airway

Variables	Polyurethane-Cuffed ETT, n	Uncuffed ETT, n
Stickler syndrome	1	2
Pierre Robin sequence	3	2
Saethre-Chotzen syndrome	1	0
Mosaic trisomy 14	0	1
Down syndrome	0	1
22q11.2 deletion syndrome	0	1
Micrognathia	1	1
Total	6	8

ETT = endotracheal tube.

Outcomes

We failed to identify an association between type of ETT used and odds of atelectasis (PUC-ETT, 24%; uncuffed ETT, 23%; OR, 1.06; 95% CI, 0.35–3.20; p = 1.00). However, the 95% CI does not exclude the possibility that uncuffed ETTs are associated with more than three-fold greater odds of developing atelectasis. Similarly, we failed to identify an association between type of ETT used and odds of developing stridor (PUC-ETT, 20%; uncuffed ETT, 13%; OR, 1.58; 95% CI, 0.43–5.81; p = 0.715). However, again, the 95% CI does not exclude the possibility that uncuffed ETTs are associated with more than five-fold greater odds of developing stridor. Last, regarding complications, we failed to identify an association between type of ETT used and odds of developing hoarseness (PUC-ETT, 20%; uncuffed ETT, 3%; OR, 7.03; 95% CI, 0.83–59.6; p = 0.10). At the time of intubation, the air leak pressure was similar in both types of ETT cases (p = 0.267). However, at the time of extubation, the air leak pressure was higher in the PUC-ETT group when compared with the uncuffed ETT group (p < 0.001). The number of patients who received IV dexamethasone and the cases of inhaled racemic epinephrine were not statistically significant between groups (Table 3).

TABLE 3.

Association Between the Frequency of Respiratory Complications and Cuffed or Uncuffed Endotracheal Tubes

Outcome Variables	Polyurethane-Cuffed ETT, n = 41	Uncuffed ETT, n = 30	p	OR (95% CI)
Atelectasis, n (%)	10 (24)	7 (23)	1.00	1.06 (0.35–3.20)
Stridor, n (%)	8 (20)	4 (13)	0.715	1.58 (0.43–5.81)
Hoarseness, n (%)	8 (20)	1 (3)	0.010	7.03 (0.83–59.6)
Air leak pressure, mean (interquartile range), cm H2O
Intubation	15 (12.5–20)	15 (10–15)	0.267	—
Extubation	30 (20–30)	15 (10–20)	< 0.001	—
IV dexamethasone, n (%)	4 (10)	2 (7)	0.98	1.51 (0.26–8.86)
Inhaled racemic epinephrine, n (%)	7 (17)	3 (10)	0.616	1.85 (0.44–7.85)

ETT = endotracheal tube, OR = odds ratio.

DISCUSSION

We evaluated the complications associated with cuffed and uncuffed ETTs during and after short-term intubation of post-palatoplasty patients without intrinsic lung disease. An unblinded randomized control study in infants less than 3 months old showed that cuffed ETTs reduced episodes of atelectasis (8). On the other hand, a single-center retrospective cohort study showed that complications with PUC-ETT versus uncuffed ETT in neonates after cardiac surgery, including the incidence of atelectasis, did not differ significantly (12). Another retrospective cohort study in pediatric patients after cardiac surgery showed no association between the incidence of ventilator-associated pneumonia and the use of PVC-ETT. However, uncuffed ETTs were used for only 7.2% of the patients in that study (13). Therefore, whether the frequency of atelectasis in the PUC-ETT group is lower than that in the uncuffed ETT group is still controversial. In our comparison based on pediatric patients with greater similarities in baseline characteristics than in the previous studies, although many other factors, such as ventilator management strategies, ETT maintenance strategies, and congenital deformities related to the upper airway, may affect the prevalence of atelectasis, our important finding is that whatever type of ETT is used, atelectasis can still occur during short-term intubation.

The possibility that more acute respiratory complications, such as subglottic edema after extubation leading to stridor, are associated with the use of a cuffed ETTs remains a concern. In the current study, we failed to identify an association between type of ETT and the odds of developing stridor and hoarseness after extubation. However, the upper limit of the 95% CI in both of these relationships indicate that we still cannot exclude the possibility that cuffed ETTs are associated to up to several-fold greater odds of these complications. The use of IV dexamethasone and inhaled racemic epinephrine as an indicator of respiratory complications were not statistically significant between the groups. Similar to our study, a previous study showed that the incidence of acute postoperative stridor was not significantly different between the cuffed (0.9%) and uncuffed tube groups (1.4%; OR, 0.63; 95% CI, 0.32–1.25) (7). The prevalence of stridor in our study population was higher than that in previous studies. This difference may be attributable to the inclusion of only patients who underwent palatoplasty in our study, since one study on palatoplasty reported that 10.1% of patients developed stridor after extubation (9). Furthermore, respiratory symptoms are difficult to assess retrospectively because their definition is subjective or varies according to the institution. Nevertheless, there were no differences between the two groups in these studies.

PUC-ETTs required greater leakage pressure than the other tubes before extubation. In our study, only patients with PUC-ETTs had a delay in extubation owing to no audible air leakage. These results may indicate that a cuffed ETT may induce edema in the upper respiratory tract during intubation. The possibility that confounding factors exist cannot be ruled out. The difference in intubation durations probably affected these results. The changes in the daily working schedule in our PICU may also have affected intubation durations, although there were no major changes in the practice of intensive care methods, extubation strategies, and recording rules during the study period. A previous prospective, randomized, multicenter study showed that the incidence of leakage, which was confirmed by 20 cm H₂O inflation pressure, was higher in the uncuffed ETT group than in the cuffed ETT group. However, in that study, the uncuffed ETT diameter was selected according to each local institutional guideline. Therefore, an uncuffed ETT with an oversized outer tube diameter may cause airway damage (14). Furthermore, our ETT selection protocol, which used a smaller size than the recommended one, may reduce the air leak pressure in the uncuffed ETT group (15). However, it is important to note that no severe complications associated with respiratory management were observed in either study.

Since this was a retrospective study of a specific population admitted to the PICU at a single institution, this study had several limitations. First, the population in this study was very specific to post-palatoplasty infants in a small sample size of patients with a limited age range at a single institution. There were no patients with intrinsic lung disease; therefore, the results are not widely generalizable. Second, the symptoms related to respiratory complications were judged subjectively by several intensivists. Further studies that objectively define these symptoms are required. Third, we checked the cuff pressure every 6 hours according to our institution’s guidelines. Because we retrospectively investigated cuff pressure, it is uncertain whether cuff pressure was appropriately controlled to ensure suitable pressure. A recent adult study suggested that persistent monitoring of cuffed pressure reduces the occurrence of post-extubation stridor and ventilator-associated pneumonia (16, 17). However, a single-center prospective randomized controlled study conducted in a pediatric population showed that protocolized 6-hourly monitoring of ETT cuff pressure in comparison with cuff inflation on each occasion owing to bedside clinical assessment did not reduce the risk of ventilator-associated pneumonia (18). Therefore, a prospective study with stricter management of cuff pressure is needed. Fourth, our study only included patients who underwent short-term intubation. Long-term intubation may result in a higher incidence of complications. However, according to our study, cuffed and uncuffed tubes were equally safe for short-term intubation. Finally, the type of surgical procedure, anesthesia duration, and procedure duration were significantly different, probably because of the different plastic surgeons. The involvement of multiple surgeons may result in different outcomes. However, we believe that the relationship between respiratory management and surgical factors is not highly correlated.

Regardless of the above-mentioned limitations, this study presents information that is very important in respiratory management in the short-term postoperative intubation strategy. Further prospective controlled studies with larger samples may help identify proper guidelines for the selection of tube type in the pediatric population.

CONCLUSIONS

The population in this study was very specific to post-palatoplasty infants without intrinsic lung disease and therefore the results are not widely generalizable; however, we failed to identify an association between type of ETT and the development of respiratory complications during and after short-term intubation. Taken together with the 95% CI of the effect size, our data indicate continued uncertainty about type of ETT that should be used for short-term intubation.