A technique to measure the intracuff pressure continuously: an in vivo demonstration of its accuracy

Effect of transesophageal echocardiography probe on tracheal perfusion pressure and ventilatory parameters in pediatric patients undergoing cardiac surgery using cardiopulmonary bypass: A prospective observational study

Background

Overinflation of cuffed endotracheal tubes and transesophageal echocardiography (TEE) probe causes increased intracuff pressure (CP) compromising tracheal perfusion pressure (TPP). Primary objective of the study was to assess CP, TPP on TEE probe insertion and examination during pediatric cardiac surgeries. Secondary objectives were to evaluate the effect of the probe on peak airway pressures (Ppeak), mean airway pressures (Pmean) and to monitor CP, TPP on cardiopulmonary bypass (CPB).

Materials and Methods

This prospective observational study included fifty patients, aged 1-5 years undergoing cardiac surgeries using CPB. Following induction, TEE probe was introduced. CP, TPP, Ppeak, Pmean were measured before insertion of TEE probe (T1), during probe insertion (T2) and examination at mid-esophageal (T3), transgastric level (T4), and on removing probe (T6). CP, TPP were monitored on CPB (T5). Statistical analysis was done using paired t-test.

Results

CP, Ppeak and Pmean increased significantly, while TPP decreased significantly from T1 to T2, T3, T4 (P < 0.001). CP, TPP decreased significantly at T5 in comparison to T6 (P < 0.001). In 48% of the patients CP increased above 30 cm H2O at T2.

Conclusion

TEE probe causes an increase in CP and decreases TPP. Constant monitoring and maintaining CP, TPP in optimum range is recommended.

A view on pediatric airway management: a cross sectional survey study

BACKGROUND

This survey aimed to investigate routine practices and approaches of clinicians on pediatric airway in anesthesia and intensive care medicine.

METHODS

A 20-question multiple-choice questionnaire with the possibility to provide open text answers was developed and sent. The survey was sent to the members of European Airway Management Society via a web-based platform. Responses were analyzed thematically. Only the answers from one representative of the pediatric service of each hospital was included into the analysis.

RESULTS

Among the members, 143 physicians responded the survey, being anesthesiologists (83.2%), intensivists (11.9%), emergency medicine physicians (2.1%), and (2.8%) pain medicine practitioners. A straight blade was preferred by 115 participants (80.4%) in newborns, whereas in infants 86 (60.1%) indicated a curved blade and 55 (38.5%) a straight blade. Uncuffed tracheal tube were preferred by 115 participants (80.4%) in newborns, whereas 24 (16.8%) used cuffed tubes. Approximately 2/3 of the participants (89, 62.2%) reported not to use routinely a cuff manometer in their clinical practice, whereas 54 participants (37.8%) use it routinely in pediatric patients. Direct laryngoscopy for routine pediatric tracheal intubation was reported by 127 participants (88.8%), while 16 (11.2%) reported using videolaryngoscopes routinely. Interestingly, 39 (27.3%) had never performed neither videolaryngoscopy nor flexible bronchoscopy in children. These results were significantly less in hospitals with a dedicated pediatric anesthesiologist.

CONCLUSIONS

This survey on airway management in pediatric anesthesia revealed that the use of cuffed tubes and the routine monitoring of cuff pressure are rare. In addition, the rate of videolaryngoscopy or flexible optical intubation was low for expected difficult intubation. Our survey highlights the need for properly trained pediatric anesthesiologists working in-line with updated scientific evidence.

Methods Used for Endotracheal Tube Cuff Inflation and Pressure Verification in Veterinary Medicine: A Questionnaire on Current Practice

Endotracheal intubation is a routine procedure in veterinary anaesthesia, yet no consensus guidelines exist for endotracheal tube (ETT) cuff inflation and pressure measurement. The aim of this study was to assess current practice of ETT cuff inflation and seal verification in veterinary medicine. An online questionnaire was distributed among veterinary professionals who administer anaesthesia, comprising six demographic and twelve ETT cuff-related questions per species. N = 348 questionnaires were completed. Cuff pressure was measured by 30% of respondents in cats, 32% in dogs and 9% in both farm animals and horses. Anaesthesia diplomates were not more likely to measure cuff pressure than others, except in cats (OR: 1.8; 95% CI: 1.1−2.9). The most frequently selected recommended range of cuff pressure was 20−30 cm H2O, regardless of species, although >30 cm H2O was selected significantly more often in horses compared to dogs, cats and farm animals. The preferred technique to verify cuff seal was minimal occlusive volume in dogs, cats and farm animals, whereas in horses, the preferred method was verification of normal capnogram waveform. ETT cuff pressure measurement remains uncommon in veterinary anaesthesia. The development of consensus recommendations for cuff inflation, including evidence-based target cuff pressure ranges for various species and different ETT models or materials, can help to improve practice.

Cuffed versus uncuffed endotracheal tubes for neonates

BACKGROUND

Endotracheal intubation is a commonly performed procedure in neonates, the risks of which are well-described. Some endotracheal tubes (ETT) are equipped with a cuff that can be inflated after insertion of the ETT in the airway to limit leak or aspiration. Cuffed ETTs have been shown in larger children and adults to reduce gas leak around the ETT, ETT exchange, accidental extubation, and exposure of healthcare workers to anesthetic gas during surgery. With improved understanding of neonatal airway anatomy and the widespread use of cuffed ETTs by anesthesiologists, the use of cuffed tubes is increasing in neonates.

OBJECTIVES

To assess the benefits and harms of cuffed ETTs (inflated or non-inflated) compared to uncuffed ETTs for respiratory support in neonates.

SEARCH METHODS

We searched CENTRAL, PubMed, and CINAHL on 20 August 2021; we also searched trial registers and checked reference lists to identify additional studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-RCTs, and cluster-randomized trials comparing cuffed (inflated and non-inflated) versus uncuffed ETTs in newborns. We sought to compare 1. inflated, cuffed versus uncuffed ETT; 2. non-inflated, cuffed versus uncuffed ETT; and 3. inflated, cuffed versus non-inflated, cuffed ETT.

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal. Two review authors independently assessed studies identified by the search strategy for inclusion, extracted data, and assessed risk of bias. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We identified one eligible RCT for inclusion that compared the use of cuffed (inflated if ETT leak greater than 20% with cuff pressure 20 cm H₂O or less) versus uncuffed ETT. The author provided a spreadsheet with individual data. Among 76 infants in the original manuscript, 69 met the inclusion and exclusion criteria for this Cochrane Review. We found possible bias due to lack of blinding and other bias. We are very uncertain about frequency of postextubation stridor, because the confidence intervals (CI) of the risk ratio (RR) were very wide (RR 1.36, 95% CI 0.35 to 5.25; risk difference (RD) 0.03, -0.11 to 0.18; 1 study, 69 participants; very low-certainty evidence). No neonate was diagnosed with postextubation subglottic stenosis; however, endoscopy was not available to confirm the clinical diagnosis. We are very uncertain about reintubation for stridor or subglottic stenosis because the CIs of the RR were very wide (RR 0.27, 95% CI 0.01 to 6.49; RD -0.03, 95% CI -0.11 to 0.05; 1 study, 69 participants; very low-certainty evidence). No neonate had surgical intervention (e.g. endoscopic balloon dilation, cricoid split, tracheostomy) for stridor or subglottic stenosis (1 study, 69 participants). Neonates randomized to cuffed ETT may be less likely to have a reintubation for any reason (RR 0.06, 95% CI 0.01 to 0.45; RD -0.39, 95% CI -0.57 to -0.21; number needed to treat for an additional beneficial outcome 3, 95% CI 2 to 5; 1 study, 69 participants; very low-certainty evidence). We are very uncertain about accidental extubation because the CIs of the RR were wide (RR 0.82, 95% CI 0.12 to 5.46; RD -0.01, 95% CI -0.12 to 0.10; 1 study, 69 participants; very low-certainty evidence). We are very uncertain about all-cause mortality during initial hospitalization because the CIs of the RR were extremely wide (RR 2.46, 95% CI 0.10 to 58.39; RD 0.03, 95% CI -0.05 to 0.10; 1 study, 69 participants; very low-certainty evidence). There is one ongoing trial. We classified two studies as awaiting classification because outcome data were not reported separately for newborns and older infants.

AUTHORS' CONCLUSIONS

Evidence for comparing cuffed versus uncuffed ETTs in neonates is limited by a small number of babies in a single RCT with possible bias. There is very low certainty evidence for all outcomes of this review. CIs of the estimate for postextubation stridor were wide. No neonate had clinical evidence for subglottic stenosis; however, endoscopy results were not available to assess the anatomy. Additional RCTs are necessary to evaluate the benefits and harms of cuffed ETTs (inflated and non-inflated) in the neonatal population. These studies must include neonates and be conducted both for short-term use (in the setting of the operating room) and chronic use (in the setting of chronic lung disease) of cuffed ETTs.

Does the endotracheal tube cuff pressure increases with transesophageal probe insertion?

Context:

The cuff pressure (CP) of the endotracheal tube (ETT) exceeding 30 cm of H₂O results in reduced perfusion of lateral mucosa of trachea leading to complications. As the posterior tracheal wall is in contact with the esophagus, there is a possibility that the insertion of transesophageal echo (TEE) probe may compress the tracheal wall and increase CP.

Aims:

This study was aimed to assess the impact of TEE probe insertion on CP in adults undergoing cardiac surgery.

Settings and Design:

Prospective observational study of 65 patients at tertiary care level hospital.

Subjects and Methods:

After balanced general anesthesia, patients were intubated with high volume low-pressure ET.TEE probe was then inserted with gentle jaw thrust. CP was measured by standard invasive pressure monitoring device at four points: T1 at baseline before TEE probe insertion; T2 maximum CP noted at TEE probe insertion; T3 at 5 min post TEE probe insertion; and T4 at post-TEE exam.

Statistical Analysis Used:

CP was compared between pairs of time points (T1 vs. T2; T1 vs. T3; and T1 vs. T4) using Mann-Whitney U test. Factors predicting CP >30 cm of H₂O at T4 were assessed by backward stepwise regression.

Results:

CP (mean ± S.D.) at T1, T2, T3, and T4 was 22 ± 3, 38 ± 10, 30 ± 6, and 30 ± 7, respectively. CP increased significantly from T1 to T2 (P < 0.001), T1 to T3 (P < 0.001), and T1 to T4 (P < 0.001). There were 26 patients (40%) with CP >30 cm of H₂O at end of TEE exam (T4). On multivariate analysis baseline, CP (T1) >20 cm of H₂O was significantly associated with CP >30 cm of H₂O at end of TEE exam with Odd's Ratio (OR) of 8.5 (1.76–41.06, P = 0.008).

Conclusions:

To conclude, the CP increases significantly with TEE probe insertion in 40% of patients exceeding a safe limit of 30 cm of H₂O. The monitoring and optimization of CP is advisable.

Clinical Outcomes of a Modified Laryngeal Mask Airway (LMA® Gastro™ Airway) During Esophagogastroduodenoscopy in Children and Adolescents: A Randomized Study

Introduction

During esophagogastroduodenoscopy (EGD), general anesthesia (GA) may be provided using a laryngeal mask airway (LMA) with the endoscope inserted behind the cuff of the LMA into the esophagus. Passage of the endoscope may increase the intracuff of the LMA. We evaluated a newly designed LMA (LMA^® Gastro™ Airway) which has an internal channel exiting from its distal end to facilitate EGD. The current study compared the change of LMA cuff pressure between this new LMA and a standard clinical LMA (Ambu^® AuraOnce™) during EGD.

Methods

Patients less than 21 years of age and weighing more than 30 kg were randomized to receive airway management with one of the two LMAs during EGD. After anesthetic induction and successful LMA placement, the intracuff pressure of the LMAs was continuously monitored during the procedure. The primary outcome was the change of intracuff pressure of the LMAs.

Results

The study cohort included 200 patients (mean age 13.6 years and weight 56.6 kg) who were randomized to the LMA^® Gastro™ Airway (n=100) or the Ambu^® AuraOnce™ LMA (n=100). Average intracuff pressures during the study period (before and after endoscope insertion) were not different between the two LMAs. Ease of the procedure was slightly improved with the LMA^® Gastro™ Airway (p<0.001).

Discussion

The LMA^® Gastro™ Airway blunted, but did not prevent an increase in intracuff pressure during EGD when compared to the Ambu^® AuraOnce™ LMA. Throat soreness was generally low, and complications were infrequent in both groups. The ease of the procedure was slightly improved with the LMA^® Gastro™ Airway compared to the Ambu^® AuraOnce™ LMA.

Evidence Based Use of Cuffed Endotracheal Tubes in Children

Historically, the use of cuffed endotracheal tubes (ETTs) was reserved for children aged 8 years or older to minimize the risks of postextubation laryngeal edema. However, since publication of a 1997 study, researchers have consistently presented evidence that appropriately used cuffed ETTs are as safe as uncuffed ETTs. Because of the advantages of cuffed ETTs in the perianesthesia setting, the transition to cuffed ETTs in children is now complete. However, risks related to using cuffed ETTs in young children increase when guidelines for safe and appropriate use are not followed. Perianesthesia practitioners caring for children must understand the implications related to ETT type, correct ETT sizing, and the monitoring and control of ETT cuff pressure. The purpose of this educational module is to present evidence-based guidelines for the appropriate use of cuffed ETTs in children less than 8 years of age in the perianesthesia setting.

Changes in Pediatric-Sized Endotracheal Tube Cuff Pressure With Elevation Gain: Observations in Ex Vivo Simulations and In Vivo Air Medical Transport

OBJECTIVES

Prolonged excessive endotracheal cuff pressure greater than 30 cmH2O is thought to cause ischemic airway injury. Excessive cuff pressure with altitude gain during air medical transport has been previously described in adult patients. It is poorly understood how pediatric-sized endotracheal tube (ETT) cuffs behave with atmospheric pressure change during flight.

METHODS

In ex vivo models 4.0, 6.0, and 8.0, ETTs restricted within scaled syringe tubing were inflated to 20 cmH2O. Pressure was measured against 1500 ft elevation gain in ground and flight models. In an in vivo observation of pediatric patient transport, change in cuff pressure was measured between takeoff and helicopter peak flight altitudes.

RESULTS

In the ex vivo ground model, endotracheal cuff pressure increased linearly with altitude and exceeded 40 cmH2O in all tube sizes. Comparable pressure change was demonstrated in the flight model. No difference was demonstrated in the degree of pressure change between ETT sizes. In the in vivo observations during patient transport, pressure increase was consistent with that seen in the ex vivo models.

CONCLUSIONS

Children who are intubated with cuffed ETTs for air medical transport are subject to excessive endotracheal cuff pressure at even low flight altitudes. Endotracheal tube size did not affect the degree of cuff pressure change, contrary to previous study. These findings need to be validated and correlated to patient clinical outcomes. The implications of these data need to be considered clinically particularly for prolonged transport of intubated pediatric patients at elevation.

Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs

OBJECTIVE

To evaluate endotracheal tube intracuff pressure (P_cuff) changes over time and the effect of these changes on air leak pressure (P_leak).

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of nine healthy adult Beagle dogs.

METHODS

In part I, in vitro measurements of P_cuff were recorded for 1 hour in eight endotracheal tubes subjected to four treatments: room temperature without lubricant (RT0L), room temperature with lubricant (RTWL), body temperature without lubricant (BT0L), and body temperature with lubricant (BTWL). In part II, nine dogs were endotracheally intubated and P_leak was evaluated at P_cuff of 25 mmHg. Subsequently, P_cuff was reset to 25 mmHg (baseline) and P_cuff measurements were recorded every 5 minutes for 1 hour. Subsequently, a second P_leak measurement was recorded at the current P_cuff. The data were analyzed using Wilcoxon signed-rank test, repeated measures anova and Mann-Whitney U test.

RESULTS

In part I, P_cuff differed significantly between the RT0L and RTWL treatments at 5-60 minutes, and between the BT0L and BTWL treatments at 5-35, 55 and 60 minutes (p < 0.05). In part II, compared with baseline pressures, mean P_cuff decreased to <18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (P_cuff range: 10.0 ± 4.9 to 13.4 ± 6.3 mmHg, mean ± standard deviation). Significant differences were observed between the first and second P_leak measurements (p = 0.034). P_leak decreased in six of nine dogs, was not changed in two dogs and increased in one dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Significant decreases in P_cuff over time were measured. P_leak may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing P_cuff more than once, especially at 10 minutes after the onset of anesthesia.

Selection of appropriate endotracheal tube size using thoracic radiography in Beagle dogs

OBJECTIVE

To determine the optimal endotracheal tube size in Beagle dogs using thoracic radiography.

STUDY DESIGN

Prospective, randomized, crossover experimental study.

ANIMALS

A total of eight healthy adult Beagle dogs.

METHODS

Lateral thoracic radiographs were used to measure the internal tracheal diameter at the thoracic inlet. This measurement was multiplied by 60, 70 and 80% to determine the outer diameter of the endotracheal tube for each dog. In each treatment, medetomidine (5 μg kg^-1) was administered intravenously (IV) for premedication. Anesthesia was induced with alfaxalone (2 mg kg^-1) IV and maintained with isoflurane. After induction of anesthesia, the resistance to passage of the endotracheal tube through the trachea was scored by a single anesthesiologist. Air leak pressures (P_leak) were measured at intracuff pressures (P_cuff) of 20 and 25 mmHg (27 and 34 cmH₂O). The results were analyzed using Friedman tests and repeated measures anova.

RESULTS

There were statistically significant increases in resistance as the endotracheal tube size increased (p = 0.003). When P_cuff was 20 mmHg, mean P_leak for the 60, 70 and 80% treatments were 9.7 ± 6.7, 16.2 ± 4.2 and 17.4 ± 3.9 cmH₂O, respectively, but no significant differences were found. When P_cuff was 25 mmHg, mean P_leak for the 60, 70 and 80% treatments were 10.6 ± 8.5, 19.7 ± 4.9 and 20.8 ± 3.6 cmH₂O, respectively, and statistically significant increases were found between treatments 60 and 70% (p = 0.011) and between treatments 60 and 80% (p = 0.020). Three dogs in the 80% treatment had bloody mucus on the endotracheal tube cuff after extubation.

CONCLUSIONS AND CLINICAL RELEVANCE

Results based on resistance to insertion of the endotracheal tube and the ability to achieve an air-tight seal suggest that an appropriately sized endotracheal tube for Beagle dogs is 70% of the internal tracheal diameter measured on thoracic radiography.

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

BACKGROUND

In children, the size of the cuffed endotracheal tube is based on various age-based formulas. However, such formulas may over or underestimate the size of the cuffed endotracheal tube. There are no data on the impact of different-sized cuffed endotracheal tubes (ETT) on the intracuff pressure in children.

AIM

The current study measures intracuff pressure with different-sized cuffed ETT.

METHOD

The study was conducted in an in vitro and in vivo phase. For the in vitro phase, 10 cuffed ETT of size 4.0, 4.5, and 5 mm internal diameter (ID) each were randomly placed inside a 1.0 cm ID plastic tube (mimicking the trachea), which was in turn connected to a 1 l test lung. After inflation of the cuff using the air leak test at a continuous positive airway pressure of 20 cmH₂ O, the intracuff pressure was measured. The in vivo phase was conducted in 100 children (4-8 years) and were randomly divided into two groups to receive either a cuffed endotracheal tube based on the Khine formula (Group R) or a cuffed endotracheal tube that was a half-size (0.5 mm ID) smaller (Group S). Following the inflation of the cuff to seal the trachea, the intracuff pressure was measured.

RESULTS

In the in vitro phase, the intracuff pressure was 45 ± 6, 23 ± 1, and 14 ± 6 cmH₂ O with size 4.0, 4.5, and 5 mm ID cuffed ETT, respectively (F-test P < 0.001 for difference among three groups). In the in vivo phase, the mean intracuff pressure in Group R was 25 ± 19 cmH₂ O vs 37 ± 35 cmH₂ O in Group S (95% CI of difference: 1, 23; P = 0.039).

CONCLUSION

If the cuffed endotracheal tube is too small, the trachea can still be sealed by inflating the cuff with additional air. However, this transforms the cuff from the intended high-volume, low-pressure cuff to an undesirable high-volume, high-pressure cuff.

The effect of mouth prop on endotracheal tube intracuff pressure in children during dental rehabilitation under general anaesthesia

Although the endotracheal tube (ETT) cuff may be associated with tracheal morbidity, cuffed tubes may reduce the aspiration risk in oral procedures. Dentists must use a mouth prop to facilitate oral visualization and to protect the oral soft tissues during dental rehabilitation under general anaesthesia (DRGA). The aim of this study was to evaluate the effect of mouth prop on endotracheal tube intracuff pressure in children during DRGA. Two-hundred and three ASA I-II patients, <18 years of age (mean: 5.3 ± 2.4 years) were included in the prospective observational study whose comprehensive dental treatment was performed under general anaesthesia. Following the induction of general anaesthesia, placement of a cuffed endotracheal tube which was an appropriate size for children was fixed. The intracuff pressure was measured intermittently after the intubation (baseline) (T0), immediately after the mouth prop (T1), 30 min after the mouth prop (T2), after taking out the mouth prop (T3) and just before extubation (T4). The mean intracuff pressure was 28.3 ± 2.01 cm H₂O at T0. The mean intracuff pressure significantly increased at T1 (30.8 ± 2.7) and T2 (29.6 ± 3.7) compared to T0 (P < 0.001). No significant differences were observed between the duration of the procedure and intracuff pressure or postoperative complications (P > 0.05). Cough, sore throat and nausea were observed in 4, 1 and 5 patients, respectively. Because a mouth prop may increase the intracuff pressure of ETT, strict measurement and readjustment of cuff pressures should be employed when used in children during DRGA.

The effect of esophagogastroduodenoscopy probe insertion on the intracuff pressure of airway devices in children during general anesthesia

Given the size of the esophagogastroduodenoscopy (EGD) probe and the compressibility of the pediatric airway, the EGD probe may increase the intracuff pressure (IP) of an airway device. The current study evaluated IP changes during EGD examination under general anesthesia in pediatric patients. Following the induction of anesthesia, a laryngeal mask airway (LMA) or endotracheal tube (ETT) was placed without neuromuscular blockade. The IP was measured at baseline, during EGD probe insertion, while the EGD probe was in place, and after probe removal. The study cohort included 101 patients (mean age 11.3 years). The airway was secured with an LMA and an ETT in 88 and 13 patients, respectively. The IP increased from 27 ± 15 cmH₂O at baseline to 34 ± 17 cmH₂O during probe insertion (p < 0.001), remained at 33 ± 16 cmH₂O while the probe was in place, and decreased to 26 ± 14 cmH₂O after probe removal. The IP of the LMA or ETT increased during EGD probe insertion and remained elevated while the probe was in place. High IP may compromise mucosal perfusion resulting in a sore throat when using an LMA or the potential for airway damage if an ETT is used. Removal of air from the cuff and titration of the IP should be considered after EGD insertion.

Cuffed endotracheal tubes for neonates and young infants: a comprehensive review

Traditionally, uncuffed endotracheal tubes (ETTs) have been used for artificial ventilation of infants and children. More recently, newer designed high-volume low-pressure (HVLP) cuffed ETTs are being used with increasing frequency in infants from birth. Considering that many paediatric anaesthetists and intensivists are already using cuffed ETTs in infants >3 kg from birth, should neonatologists be doing the same? This review examines the reasons behind the traditional use of uncuffed ETTs and the problems associated with their use; newer HVLP cuffed ETTs and what they can potentially offer neonates; and reviews evidence from studies comparing the use of cuffed and uncuffed ETTs in neonates and small infants.

Changes in intracuff pressure of a cuffed endotracheal tube during surgery for congenital heart disease using cardiopulmonary bypass

BACKGROUND

With the development of newer polyurethane cuffed endotracheal tubes (cETTs), there has been a shift in clinical practice among pediatric anesthesiologists. Despite improvements in design, excessive inflation of the cuff can still compromise tracheal mucosal perfusion. Several perioperative factors can affect the intracuff pressure (CP), and there is no consensus on safe CP in pediatric patients undergoing repair of congenital cardiac disease (CHD) utilizing cardiopulmonary bypass (CPB). In the current study, the CP was continuously monitored in pediatric patients undergoing surgery for CHD.

METHODS

After IRB approval, this observational study was conducted on pediatric patients who underwent repair of CHD using CPB with a cETT in place. After anesthetic induction and endotracheal intubation, the cuff was inflated using the air leak technique while maintaining a continuous positive airway pressure of 20 cmH2 O. After inflation, the CP was continuously monitored throughout the procedure. In addition, temperature and mean arterial pressure (MAP) were also recorded.

RESULTS

The study included 33 patients who ranged in age from 1 month to 15.3 years. Their weight ranged from 4.0 to 83.6 kg. Six patients were excluded from the analysis due to the need to add or remove air from the cuff, leaving 27 patients for data analysis for cuff pressure over time. The baseline CP at the time of inflation was 16.1 ± 7.6 cmH2 O. With the use of CPB and initiation of hypothermia, when compared to the baseline, the CP decreased by -0.7 ± 5.8 cmH2 O at 35-37°C, -9.1 ± 8.4 cmH2 O at 31-33°C, -7.8 ± 6.2 cmH2 O at 27-29°C, and -11.1 ± 6.0 cmH2 O at <27°C. With rewarming, the CP increased back to the baseline level (-3.5 ± 7.0 cmH2 O).

CONCLUSION

There was a significant decrease in the CP during CPB and associated hypothermia. This may offer some protection for mucosal perfusion during CPB which is usually associated with lower than normal MAP. However, the decrease in the CP may compromise the tracheal seal which may not offer the intended protection for the airway from aspiration.

Pediatric airway anatomy may not be what we thought: implications for clinical practice and the use of cuffed endotracheal tubes

One of the long held tenets of pediatric anesthesia has been the notion that the pediatric airway is conical shape with the narrowest area being the cricoid region. However, recent studies using radiologic imaging techniques (magnetic resonance imaging and computed tomography) or direct bronchoscopic observation have questioned this suggesting that the narrowest segment may be at or just below the glottic opening. More importantly, it has been clearly demonstrated that the airway is elliptical in shape rather than circular with the anterior-posterior dimension being greater than the transverse dimension. These findings coupled with the development of a new generation of cuffed endotracheal tubes (ETTs) with a thin, polyurethane cuff have caused a transition in the practice of pediatric anesthesiology with an increased use of cuffed ETTs, even in neonates and infants. The following article reviews the historical data leading to the assumption that the pediatric airway is conical as well as the more recent imaging and direct bronchoscopic observational studies which refute this tenet. The transition to the use of cuffed ETTs is discussed and potential advantages presented in both the operating room and the intensive care unit. Issues regarding the monitoring of intracuff pressure and techniques to limit potential morbidity related to a high intracuff pressure are outlined.

Changes in intracuff pressure of a cuffed endotracheal tube during prolonged surgical procedures

BACKGROUND

With the introduction of redesigned cuffed endotracheal tubes (ETTs), there has been an increasing trend toward their use in pediatric patients. Despite improvements in design, an unintended and prolonged hyperinflation of the cuff can compromise tracheal mucosal perfusion. The current study prospectively monitors changes in intracuff pressure continuously in pediatric patients undergoing prolonged surgical procedures.

METHODS

The study was conducted on pediatric patients who were scheduled to undergo prolonged surgical procedures (more than 4h) with a cuffed ETT. After placement of the cuffed ETT, the cuff was inflated using the air-leak test with a CPAP of 20cmH2O in the anesthesia circuit. After inflation, the inflating port of the pilot balloon was connected to the transducer of the invasive pressure monitoring device using our previously described technique to continuously measure the intracuff pressure. Measurements were recorded every 15min for the first 1h, and then every 30min throughout the surgical procedure.

RESULTS

The study cohort included 30 patients who ranged in age from 1.2 to 17.6 years and in weight from 9.4 to 113.4kg. There were 16 boys and 14 girls. The size of the cuffed ETT ranged from 3.5mm to 8.0mm ID. The baseline intracuff pressure at the time of inflation was 17.6±8.8cmH2O. The absolute change in the intraoperative intracuff pressure when compared to the baseline intracuff pressure ranged from -25.8 to +16.3cmH2O. In 9 patients (30%), the decrease of the intracuff pressure was ≥10cmH2O. In 6 patients (20%), the increase of the intracuff pressure was ≥10cmH2O. In 5 of 30 patients (17%), the absolute intracuff pressure was greater than 30cmH2O at least once intraoperatively. In no patient, did the intracuff pressure remain the same as the baseline throughout the procedure.

CONCLUSION

We noted significant variations in the intracuff pressure during prolonged surgical procedures. These unintended changes, both increases and decreases, may impact the perioperative course of patients. Our study suggests the need for continuously monitoring intracuff pressure if a cuffed ETT is used in children for prolonged surgical procedures.