Cuffed endotracheal tubes in children: the effect of the size of the cuffed endotracheal tube on intracuff pressure

The evaluation of endotracheal tube cuff pressure in pediatric patients by subjective inflation techniques: a prospective observational study

BACKGROUND

Cuffed endotracheal tubes (ETTs) are commonly used in pediatric patients, with the gold standard for measuring cuff pressure being a cuff pressure manometer. However, this equipment is not always available in every operating room. Subjective inflation techniques, such as the minimal occluding volume (MOV) technique and the stethoscope-guided (Steth) technique, offer convenient and safe alternatives to standard methods but do not provide quantitative measurements. This study aimed to evaluate ETT cuff pressures and volumes of air inflated using the two subjective techniques (MOV and Steth) in pediatric patients.

METHODS

This prospective observational study was conducted at the Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Thailand. We included healthy pediatric patients aged 2 to 7 years undergoing elective surgeries under general anesthesia with a cuffed ETT. The primary objective of this study was to compare the mean ETT cuff pressures and volumes of air inflated using the two subjective inflation techniques (MOV and Steth method). The secondary objectives include identifying factors associated with inappropriate inflation and evaluating post-intubation complications.

RESULTS

Sixty-four pediatric patients were analyzed. The overall mean ETT cuff pressure was 26.52 ± 8.68 cmH2O. The target was achieved in 46.88% of patients, with overinflation in 32.81% and underinflation in 20.31%. The mean ETT cuff pressure in the MOV group was 27.77 ± 8.89 cmH2O and in the Steth group was 25.33 ± 8.34 cmH2O, with a non-significant mean difference of 2.44 cmH2O (95% CI [-1.89, 6.77], p = 0.264). The mean volume of air inflated in the MOV group was 0.78 ± 0.25 ml, and in the Steth group was 0.68 ± 0.22 ml, with a non-significant mean difference of 0.10 ml (95% CI [-0.01, 0.22], p = 0.084). Younger age, lower weight, and shorter height were significantly associated with an increased risk of overinflation. An ETT size with an internal diameter (ID) of 5 mm was significantly associated with an increased risk of underinflation. No post-intubation complications were reported.

CONCLUSIONS

Subjective inflation techniques (MOV or Steth) achieve target ETT cuff pressures in less than 50%, and carry the risks of both overinflation and underinflation, even without post-intubation complications.

TRIAL REGISTRATION

TCTR20211016001 (registered with the Thai Clinical Trials Registry on October 16, 2021).

[Inhalation anesthesia in the cat: Development of cuff pressure when using nitrous oxide]

OBJECTIVE

During inhalation anesthesia with nitrous oxide in oxygen the pressure in the cuff of the endotracheal tube may increase due to diffusion of nitrous oxide into the cuff. The aim of the study was to investigate the development of cuff pressure during nitrous oxide anesthesia under clinical conditions in feline patients and to identify possible influencing factors such as tube size and gas flow rate.

MATERIAL AND METHODS

The prospective study included cats scheduled for inhalation anesthesia with nitrous oxide for a minimum duration of 60 minutes at the Department for Small Animals of the University of Leipzig. Cuff pressure was adjusted with a cuff manometer and its development was recorded.

RESULTS

In total, the cuff pressure values of 24 cats were recorded. Animals were allocated into groups by tube size (ID 4.0 mm and ID 4.5 mm) and by fresh gas flow rate: low flow rate (0.6 l/min) and high flow rate (3 l/min). During anesthesia, cuff pressure increased over time, with statistical significance occurring from 45 minutes onwards in comparison to the initial cuff pressure (p=0.005). After 60 minutes, there was a mean cuff pressure increase of 3 cmH2O. Despite this moderate mean increase, highly variable pressure values up to 48 cmH2O in individual animals were recorded. No cat reached the termination criterion of 60 cmH2O cuff pressure. Effects of tube size (p=0.63) and flow rate (p=0.334) on the cuff pressure were not evident.

CONCLUSION

After a period of 45 minutes of nitrous oxide administration, a significant increase in cuff pressure occurs in the cat. However, tube size and total gas flow rate do not seem to influence the cuff pressure development.

CLINICAL RELEVANCE

When using nitrous oxide during inhalation anesthesia, regular cuff pressure evaluation and correction are necessary and hence recommended in feline patients. As individual pressure changes may be highly variable, no fixed recommendations for optimal management are possible.

Pre-hospital emergency cricothyrotomy in dogs part 2: Airway sealing and ventilation using cricothyrotomy tubes

Cricothyrotomy (CTT) has been recommended for use in the pre-hospital setting for military working dogs and Operational K9s during airway emergencies. Although the CTT can establish a patent airway for spontaneous ventilation, the ability to seal the airway and provide positive pressure ventilation (PPV) using tubes designed for humans has not been determined. Using various CTT tubes placed in cadaver dog airways, this study aimed to determine: (1) Whether the tube cuff could create a functional airway seal with safe intra-cuff pressures; (2) The magnitude of delivered tidal volume (TV) loss during a standard breath to assess the possibility of delivering an adequate tidal volume with a bag-valve device (BVM); (3) The best performing tubes for either test; (4) The reasons behind the findings using observations from upper airway endoscopy, dissection, and measurements. Cadaver dogs of similar weights to MWD and Operational K9 breeds had various CTT tubes placed including three from commercial kits, a standard endotracheal tube, and a tracheostomy tube. The minimum occlusive volume technique was used to inflate the tube cuff and a pressure ≤ 48 cm H₂O with an adequate seal was considered successful. Individual TVs were calculated for each dog and added to the volume lost during delivery of a standard breath from an ICU ventilator. Endoscopy and airway dissection were performed to assess the relationship between tubes cuffs and the airway. The tubes from the CTT kits performed poorly with regards to producing an airway seal with the H&H tube failing to seal the airway all tests. Tracheal dimensions were significantly associated with successful airway sealing (P = 0.0004). Tidal volume loss could be compensated using a BVM in 34/35 tests with the H&H tube in cadaver 8 the only to fail. Tracheal airway sealing is influenced by airway anatomy when tube cuffs are inflated to a target pressure and larger tubes do not always provide a better seal. The CTT tubes tested have the potential to facilitate ventilation with a BVM under the conditions set in this study. The 8.0 mm endotracheal tube performed the best and the H&H the worst in both tests.

The impact of esophageal device insertion on cuff pressure of endotracheal tube: a literature review and meta-analysis

The impact of intraoperative esophageal device insertion (EDI) on endotracheal tube (ET) cuff inflation pressure remains unclear. Electronic databases including Medline, Embase, Google scholar, Web of Science™ and Cochrane Central Register of Controlled Trials were searched for studies involving EDI after placement of ETs from inception to July 7, 2022. The primary outcome was risk of high cuff pressure, while the secondary outcomes were increases in cuff pressure following EDI. Difference between adults and children was investigated with subgroup analysis. There were ten eligible studies (observation study, n = 9, randomized controlled study, n = 1) involving a total of 468 participants. EDI notably increased the risk of high cuff pressure (n = 7, risk ratio: 12.82, 95% confidence interval: 4.9 to 33.52, subgroup analysis: p = 0.008). There were significant elevations in cuff pressure in adults and children both during (13.42 and 7.88 cmH₂O, respectively, subgroup analysis: p = 0.15) and after (10.09 and 3.99 cmH₂O, respectively, subgroup analysis: p = 0.0003) EDI. Our results revealed an over 12-fold increase in the risk of high endotracheal tube cuff pressure in patients, especially adults, receiving EDI under endotracheal anesthesia. There were significant increases in both adults and children despite a higher increase in the former after device insertion.

Choosing endotracheal tube size in children: Which formula is best?

OBJECTIVES

Various formulae have been suggested to calculate the appropriate sized endotracheal tube in children. The current study prospectively compares three commonly used formulae for selection of cuffed endotracheal tubes in children.

METHODS

Patients were randomized to one of three formulae (Duracher, Cole, or Khine) to determine the size of the cuffed endotracheal tube for endotracheal intubation. The fit of the tube was noted and intracuff pressure was measured using a manometer. The postoperative incidence of stridor, throat pain/soreness, and hoarseness was noted in the post-anesthesia care unit at 2, 4 and 24 h after the procedure.

RESULTS

The study cohort included 135 patients less than or equal to 8 years, equally divided into three groups based on age, weight, and gender. There was no difference in the intracuff pressure, the volume required to seal the airway, or the number of times in which the intracuff pressure was greater than or equal to 20 or 30 cm H₂O among the three groups. Six tube changes were required in the Cole group while no tube changes were required in the Duracher group (p < 0.05). The postoperative incidence of adverse events (throat pain, hoarseness, and stridor) at 0-2 h, 2-4 h, and 24 h was higher in the Cole group when compared to the Duracher group.

CONCLUSION

When using an endotracheal tube with a polyurethane cuff, the Duracher formula provided the best estimate for choosing the correct size.

Tracheal tube size in adults undergoing elective surgery - a narrative review

Tracheal tubes are routinely used in adults undergoing elective surgery. The size of the tracheal tube, defined by its internal diameter, is often generically selected according to sex, with 7-7.5 mm and 8-8.5 mm tubes recommended in women and men, respectively. Tracheal diameter in adults is highly variable, being narrowest at the subglottis, and is affected by height and sex. The outer diameter of routinely used tracheal tubes may exceed these dimensions, traumatise the airway and increase the risk of postoperative sore throat and hoarseness. These complications disproportionately affect women and may be mitigated by using smaller tracheal tubes (6-6.5 mm). Patient safety concerns about using small tracheal tubes are based on critical care populations undergoing prolonged periods of tracheal intubation and not patients undergoing elective surgery. The internal diameter of the tube corresponds to its clinical utility. Tracheal tubes as small as 6.0 mm will accommodate routinely used intubation aids, suction devices and slim-line fibreoptic bronchoscopes. Positive pressure ventilation may be performed without increasing the risk of ventilator-induced lung injury or air trapping, even when high minute volumes are required. There is also no demonstrable increased risk of aspiration or cuff pressure damage when using smaller tracheal tubes. Small tracheal tubes may not be safe in all patients, such as those with high secretion loads and airflow limitation. A balanced view of risks and benefits should be taken appropriate to the clinical context, to select the smallest tracheal tube that permits safe peri-operative management.

Cuffed pediatric endotracheal tubes-Outer cuff diameters compared to age-related airway dimensions

BACKGROUND

Reliable sealing of the pediatric airway requires appropriately sized tracheal tube cuffs. The aim of this study was to compare residual cuff diameters of pediatric tracheal tubes with pediatric airway dimensions.

METHODS

Cuff diameters of five different brands of locally marketed pediatric cuffed tracheal tubes with internal diameters of 3.0-7.0 mm were measured at a cuff pressure of 20 cm H₂ O and compared with cuff diameters indicated by their manufacturers. The latter values were compared to tracheal dimensions using the Motoyama and Khine formulas for cuffed tracheal tube size selection.

RESULTS

There is considerable heterogeneity in cuff diameters among pediatric tracheal tube brands, except for two brands from different manufacturers (Halyard and Parker Medical) which were identically designed. Cuffs made from polyurethane revealed fewer differences (91%-118%) between measured and manufacturer-indicated values for outer cuff diameters than did those made from polyvinylchloride (91%-146%). Particularly in smaller sized tracheal tubes, cuffs did not reach 100% of the tracheal lateral diameter, while others were oversized in larger tracheal tubes, independent of the two formulas used for cuffed tracheal tube size selection. Cuff diameters indicated by the manufacturer corresponded to 86%-188% of the median and 68%-157% of the maximum mid-tracheal lateral diameter of the corresponding upper age range.

CONCLUSION

Our findings show that many of the cuff diameters of currently marketed tracheal tube brands lack an age-related anatomical rationale. A proposal for age-related anatomically based cuff diameters is provided for both recommendations for cuffed tracheal tube size selection in children.

Cuffed Versus Uncuffed Endotracheal Tubes in Pediatrics: A Meta-analysis

Background

Cuffed and uncuffed endotracheal tubes are commonly used for pediatric patients in surgery and emergency situations. It is still controversial which approach should be adopted. The purpose of the study was to compare the application of cuffed and uncuffed endotracheal tubes in pediatric patients.

Methods

We searched PubMed, Web of Science and Cochrane Library for clinical trials, which compared the two applications in children. The study characteristics and clinical data were summarized by two independent reviewers. Meta-analysis of the data was done using Revman 5.3 software.

Results

6 studies with 4141 cases were included in this meta-analysis. The pooling analysis showed that more patients need tube changes in uncuffed than cuffed tubes (OR: 0.07, 95% CI: 0.05-0.10, P < 0.00001). However, there were no differences on intubation duration, reintubation occurrence, accidental extubation rate, croup occurrence and racemic epinephrine use during the intubation process. Also we didn't find any differences on laryngospasm and stridor occurrence after extubation.

Conclusions

Our study demonstrated that uncuffed endotracheal tubes increased the need for tube changes. Other incidences or complications between the two groups had no differences. Cuffed tubes may be an optimal option for pediatric patients. But more trials are needed in the future.