Prediction of endotracheal tube size in the pediatric age group by ultrasound: A systematic review and meta-analysis.

Anatomical differences in the airway in pediatric patients, compared to adults pose many challenges during endotracheal intubation, such as selecting the proper sized endotracheal tube (ETT) during intubation. Our primary objective was to assess how accurate is ultrasound (US) co-relation in comparison to standard age-based formulas in pediatric patients. Meta-analysis was registered in PROSPERO 2020, CRD42020220041. Online literature available in PubMed, Cochrane, and Embase, Goggle scholar was searched from year 2000 till November 30, 2020, using relevant Mesh terms, ('airway US' OR (('airway'/exp OR airway) AND ('US'/exp OR US))) AND ('endotracheal intubation'/exp OR 'endotracheal intubation') AND ('pediatric'/exp OR pediatric)" to Predict endotracheal tube size/placement in pediatric age (neonate till 18 years) by the US. Bibliographic cross-references of selected publications were further manually screened. The full texts of each article were studied, once the abstract was found appropriate independently by two reviewers. A total of 48 papers published between 2010 and 2020 were identified as relevant and read in detail. Average numbers of patients were 86 and total numbers of patients were 1978. Most of the studies included pediatric patients posted for elective surgeries under general anesthesia and excluded emergency procedures, known laryngeal or tracheal pathology, high-risk patients, recent upper respiratory tract infections or allergy to ultrasound gel. A total of 18 independent correlations were analyzed. Final combined r value calculated from all the included articles was 0.824 (95% CI 0.677, 0.908) with a P < 0.00001 {strong co-relation (r > 0.80)}. Q statistic of 756.484, and I2 statistics of 97.53% showed a large degree of heterogeneity in the effect size across the studies. Use of US for upper airway in pediatric patients is an effective modality and can effectively predict endotracheal tube size estimations in comparison to standard age-based or height-based formulae in the pediatric age group. US is a non-invasive, cost-effective, portable, and reproducible technique as compared to CT and MRI. It also takes less time with increasing expertise and experience.

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

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.

Arthur Guedel and the Ascendance of Anesthesia: A Teacher, Tinkerer, and Transformer.

At the beginning of the twentieth century, anesthesia was an emerging field without permanent departments, exclusive practitioners, or academic residency programs. Instead, surgeons and nurses administered anesthetic gases in an ad-hoc fashion, exposing patients to the perilous risks of general anesthesia. Dr. Arthur Guedel was a general practitioner from rural Indiana who unexpectedly became an integral part of anesthesia's evolution into a safety conscience and formally recognized expertise. Beginning during his military service in World War I, he refined the stages of ether anesthesia and produced the definitive textbook on inhalational anesthetics. During the prolific career that followed, Guedel also introduced ground-breaking devices for patient-controlled analgesia, cuffed endotracheal intubation, and oral airway patency. His inclusive mentorship, collaborative research, and innovative instruments exemplify his role as a multitalented tinkerer, teacher, and transformative leader. This essay examines Guedel's pioneering contributions and the scope of his influence, all of which revolutionized anesthesia and expanded surgeons' operative capability. Through the lens of Guedel's personal and professional life, this essay further illustrates how the diverse, interdisciplinary, and cutting edge characteristics of the practice itself contributed to anesthesia's increased importance in modern medicine.

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.

Selecting an Appropriate Cuffed Endotracheal Tube Using Ultrasound of the Cricoid in a Child with Down Syndrome.

A 7-year-old girl (height, 94 cm; weight, 15.1 kg) with Down syndrome was scheduled for right patellar dislocation repositioning. The ultrasonographically measured internal transverse width of the cricoid before intubation was 7.8 mm. Attempted insertion of a cuffed Mallinckrodt® endotracheal tube (ETT) (internal diameter, 5.0 mm; deflated cuff portion, 8.4 mm diameter) failed. In contrast, the insertion of a cuffed Microcuff® ETT (5.0 mm ID; deflated cuff portion, 7.3 mm diameter) was successful. Thicker folds in the deflated cuff of the Mallinckrodt ETT could have hindered passage through the vocal cord, including the cricoid region. It is becoming standard to use the ultrasonographically measured internal width of the cricoid when choosing cuffed paediatric ETTs, and this approach may be suitable for patients with Down syndrome as well. In these children, approximately 20% of uncuffed ETTs inserted were one or two sizes smaller in diameter than those predicted for the same age. We may choose the ETT size in reference to an ultrasonographically obtained internal transverse width of the cricoid, stated outer diameter (OD) by the producer, and the actual OD depending on the cuff bulk instead of a tube size calculation in patients with growth retardation.

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 Transesophageal Echocardiography Probe Placement on Intracuff Pressure of an Endotracheal Tube in Infants and Children.

OBJECTIVES: To evaluate the effects of transesophageal echocardiography (TEE) probe insertion on the endotracheal cuff pressure (CP). DESIGN: Prospective observational study. SETTING: Single standing, not-for-profit pediatric hospital. PARTICIPANTS: A total of 80 pediatric patients (aged 6 days to 18.4 years) who underwent cardiac surgery and intraoperative TEE. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Following anesthesia induction and endotracheal intubation, the CP was recorded at 4 points: before the insertion of the TEE (P1), at TEE insertion (P2), during TEE examination (P3), and after the probe was advanced into the stomach (P4). Twenty patients were enrolled in each of the following age groups:<1 year of age; 1-4 years of age; 5-8 years of age; and 9-18 years of age. CP was compared between pairs of time points using paired t-tests, and differences in CP over time were compared among age groups using repeated-measures analysis of variance. CP at P1, P2, P3, and P4 was 18.7±11.6, 26.7±14.4, 22.3±12.4, and 20.6±12.6 cmH2O, respectively. Although CP significantly increased from P1 to P2 (p<0.001), there was no significant difference between P1 and P4 (95% CI; -0.3 to 4.1; p = 0.083). There was no significant difference in CP change based on the age of the patient. CONCLUSION: Following a transient increase in CP with TEE probe insertion, the CP returned to baseline after the tip of the TEE probe was advanced into the stomach. There was no variation among age groups in the magnitude of the CP change during the study.

Cuff pressure monitoring by manual palpation in intubated patients: How accurate is it? A manikin simulation study.

BACKGROUND: Endotracheal intubation (ETI) for mechanical ventilation has a central role in the Intensive Care Unit (ICU). ETI is one of the main risk factors for the development of ventilator-associated pneumonia (VAP) as its presence reduces the natural defences of the upper airway and allows the micro-suction of secretions in the airways. In order to minimise such complications, it is fundamental to maintain a suitable pressure inside the tube cuff. AIM AND SCOPE: The main objective of the present study is to evaluate the effectiveness and reliability of palpation method, performed with the operators fingers, for detecting the tube cuff pressure. RESULTS: The study was performed using a manikin to test the pressure of the ETT cuff, on a sample constituted by nurses employed in three Italian ICU from two different Umbrian hospitals. From a total of 68 participants, detection by palpation method revealed to be not correct in 68% of cases; in particular, only 10% of respondents can correctly detect a pressure in the recommended range (20-30cmH2O) using palpation. Moreover it was possible to highlight that the participation in emergency courses has a positive effect on the correct measurement of cuff pressure using the palpation method (V=0.501). CONCLUSIONS: The study, in agreement with the literature, confirms the thesis that the palpation method is inadequate to determine an estimate of the pressure existing inside the cuff.

Residual volume in the cuff of the endotracheal tube when the pilot balloon is torn off instead of deflated using a syringe.

BACKGROUND: In recent years, there has been a shift in airway management with the use of cuffed endotracheal tubes (ETT) in pediatric patients. While the use of a syringe to deflate the cuff is generally recommended, anecdotal observations suggest that some healthcare practitioners tear off the pilot balloon from ETT to deflate the cuff. This study was conducted to estimate the residual volume in the cuff when the pilot balloon is torn off for deflation. METHOD: The in vitro study was conducted in three phases. In phases 1 and 2, various sized cuffed ETTs (3.0, 4.0, and 5.0 mm) were inflated to achieve an intracuff pressure of 20-30 cmH2O in open atmosphere (phase 1) or inside a tube to simulate external pressure from the tracheal wall (phase 2). The pilot balloons were ripped off and the residual volume in the cuff was measured. The process was repeated using 10 ETTs of each of the 3 sizes. In phase 3, the same process was repeated using ten, size 7.0 cuffed ETTs inflated in an intubating mannequin. RESULTS: In phase 1, the percentage of the remaining residual volume was 60.7, 72.8, and 69.5% in 3.0, 4.0, and 5.0 mm ETTs respectively. Although the percentage of residual volume in phases 2 and 3 was less than phase 1, the residual volume in phases 2 and 3 still averaged approximately 60-70% of the volume required for cuff inflation. In one case, the pilot balloon tube was completely occluded and the residual volume in the cuff could not be expelled even with external pressure. CONCLUSION: Since significant percentage of the volume remained in the cuff after tearing off the pilot balloon tube with one being completely occluded, we would not recommend this method for cuff deflation.

Changes in intracuff pressure of cuffed endotracheal tubes while positioning for adenotonsillectomy in children.

BACKGROUND: When using cuffed endotracheal tubes (cETTs), changes in head and neck position can lead to changes in intracuff pressure. AIM: The aim of this study was to assess the combined effect of neck extension, shoulder roll placement, and Crowe-Davis retractor use during adenotonsillectomy on the intracuff pressure of cETTs in children. METHODS: Patients <18 years of age undergoing adenotonsillectomy under general anesthesia following the placement of a cETT were included in the study. After inflation of the cuff to seal the trachea, using the leak test, baseline intracuff pressure was recorded and then continuously monitored. After neck extension, placement of a shoulder roll, insertion of the Crow-Davis retractor, suspension from a Mayo stand, and positioning for surgery, the intracuff pressure was recorded again. RESULTS: The study cohort included 84 patients, ranging in age from 0.9 to 17 years (5.7 ± 3.9 years). In 46 patients (54.8%), the intracuff pressure increased from baseline after positioning for adenotonsillectomy. In 12 of these patients (14.3%), the intracuff pressure was >30 cm H2O. The intracuff pressure decreased in 28 patients (33.3%), while no change was noted in 10 patients (11.9%). Overall, the general trend was an increase in intracuff pressure from 15.9 ± 7.8 cm H2O to 18.9 ± 11.6 cm H2O. CONCLUSION: Both increases and decreases in the intracuff pressure may occur following positioning of the pediatric patient for adenotonsillectomy. An increase in intracuff pressure may result in a higher risk of damage to the tracheal mucosa. A decrease in the intracuff pressure can result in an air leak resulting in inadequate ventilation, increased risk of aspiration, and even predispose to airway fire if oxygen-enriched gases are used. Continuous intracuff pressure monitoring or rechecking the intracuff pressure after positioning for adenotonsillectomy may be indicated.

An in vitro and in vivo validation of a novel color-coded syringe device for measuring the intracuff pressure in cuffed endotracheal tubes.

BACKGROUND: The clinical practice of pediatric anesthesiology has changed with a transition to the use of cuffed endotracheal tubes (ETTs) in infants and children. The monitoring of intracuff pressure has been suggested as one means to limit the potential for damage to the tracheal mucosa. The current study evaluates the accuracy of a novel, color-coded syringe device which provides three zones (green, clear, and red) to estimate the intracuff pressure. METHOD: The study was conducted in two phases. Phase 1 was an in vitro study where cuffed ETTs of sizes 4.0 mm, 5.0 mm and 6.0 mm ID were placed into polyvinylchloride tubing of appropriate sizes. A manometer and the syringe device were simultaneously attached to measure the intracuff pressure at the middle of the 3 different zones on the device (red, clear, and green). Phase 2 was an in vivo study where the syringe device and the manometer were simultaneously attached to the pilot balloon to measure the intracuff pressure and the corresponding zone on the color-coded syringe following endotracheal intubation. Statistical analysis included a descriptive reporting of the mean ± SD, median, range, and 95% confidence intervals (CI) of the actual intracuff pressure readings at the three zones of the syringe device during both its in vitro and in vivo use. RESULTS: For phase 1 of the study, the 95% CI for the green, clear, and red zones were 21.5-21.8, 29.2-29.5, and 46.5-47.4 cmH2O respectively. This correlated well with the manufacturer reported values of 20-30, 30-40, and 40-60 cmH2O for the 3 zones (green, clear, and red respectively). Phase 2 of the study included 200 patients ranging in age from 0.1 to 21.8 years (6.7 ± 5.1 years) and in weight from 4.0 to 129.1 kilograms (29.4 ± 23.3 kgs). The size of the ETTs ranged from 3.0 to 7.0 mm ID. The intracuff pressure measured by the manometer ranged from 4 to 65 cmH2O (27.6 ± 9.7 cmH2O). The 95% CI for the green, clear, and red zones were 20.5-21.7, 27.7-29.1, and 41.2-46.5 cmH2O respectively. There was no significant differences noted when comparing different patient ages or sizes of ETT. CONCLUSION: The current study demonstrates a clinically acceptable correlation between the zones on this novel, color-coded syringe device and the actual measurement of the intracuff pressure obtained by a manometer for both in vitro and in vivo use. This device is a simple, reliable, portable and affordable method to monitor intracuff pressure.

An in vitro and in vivo validation of a novel monitor for intracuff pressure in cuffed endotracheal tubes.

BACKGROUND: The clinical practice of pediatric anesthesiology has changed with increasing use of cuffed endotracheal tubes (cETTs) in infants and children. To limit the risk of tracheal mucosal damage, regular monitoring of intracuff pressure (CP) is necessary. This study evaluates the efficacy and accuracy of a novel syringe device that provides a digital readout of the CP. METHODS: The study was conducted in two phases. In phase 1, an in vitro study, cETTs of sizes 4.0, 5.0, and 6.0 mm ID were placed into polyvinylchloride tubing of appropriate sizes. The cuffs were then inflated, and the CP was measured simultaneously using the syringe device and a manometer. In phase 2, an in vivo study on 200 pediatric patients, the syringe device and the manometer were simultaneously attached to the pilot balloon to measure the CP following endotracheal intubation. Statistical analysis included linear regression analysis and Bland-Altman comparison. RESULTS: Linear regression analysis of the in vitro study demonstrated an R2 value of 0.9989. Bias and precision were -1.92 ± 0.62 with 95% level of agreement (LOA) ranging from -3.13 to -0.72. For the in vivo study, the linear regression analysis demonstrated an R2 value of 0.9943. The bias and precision were -0.53 ± 0.68 with 95% LOA ranging from -1.86 to 0.81. CONCLUSION: The study has demonstrated clinically acceptable correlation between the CPs obtained from the standard manometer and the syringe device both in vitro and in vivo. This device is a simple, reliable, portable, and affordable method to monitor CP.

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

OBJECTIVE: A major concern with the use of cuffed endotracheal tubes (cETT) in children is hyperinflation of the cuff which may compromise tracheal mucosal perfusion. To measure the intracuff pressure (CP), we devised a method using the transducer of an invasive pressure monitoring device. The objective of the study was to test the accuracy and validity of this device for instantaneous and continuous CP monitoring. METHODS: The study was conducted in 2 phases. In Phase 1 (200 pediatric patients), after inflation of the cuff, the CP was measured using the standard manometer and the transducer simultaneously. In Phase 2 (20 pediatric patients), the transducer was left connected to the pilot balloon of the ETT to obtain a continuous CP reading and the standard manometer was used to measure the CP at 5-min intervals. Statistical analysis included a Bland-Altman comparison and linear regression analysis. RESULTS: In Phase 1, linear regression analysis demonstrated an R2 value of 0.9956. The bias was 0.30 cmH2O, the precision was 0.75 cmH2O, and the 95% level of agreement (LOA) ranged from -1.16 to 1.77 cmH2O. In Phase 2, the linear regression analysis revealed an R2 value of 0.9846. The bias was 0.28 cmH2O, the precision was 0.7 cmH2O, and the 95% LOA ranged from -1.1 to 1.66 cmH2O. CONCLUSION: Our study demonstrates that when cETTs are used in the pediatric population, the transducer of the invasive pressure monitoring device can be used reliably to measure the CP at the time of inflation and continuously thereafter.

The relationship between head and neck position and endotracheal tube intracuff pressure in the pediatric population.

BACKGROUND: Over the past few years, there has been a change in clinical practice with a transition to the use of cuffed instead of uncuffed endotracheal tubes (ETTs) in pediatric patients. These changes have led to concerns regarding unsafe intracuff pressures in pediatric patients, which may result in postoperative morbidity. To avoid these issues, it is generally suggested that the intracuff pressure be maintained at ≤30 cmH2 O. The current study prospectively assesses the changes in intracuff pressure related to alterations in head and neck position in pediatric patients. METHODS: Patients less than 18 years of age, undergoing surgery, requiring endotracheal intubation with a cuffed ETT were eligible for inclusion. No alteration in the technique of anesthetic induction or maintenance was required for the study. Following endotracheal intubation and inflation of the cuff with the head and neck in a neutral position, the intracuff pressure was measured. The intracuff pressure was then subsequently measured with the head turned to the right, head turned to the left, head and neck flexed, and head and neck extended. RESULTS: A total of 200 patients were included in the study resulting in a total of 1000 intracuff pressure readings. When compared to the neutral position, the intracuff pressure increased in 545 instances (68.1%) with changes in position of the head and neck. An increase in intracuff pressure was noted more frequently and to the greatest degree with head and neck flexion. The pressure decreased in 153 instances (19.1%), most frequently with neck extension. CONCLUSION: Significant changes in the intracuff pressure occur with changes in head and neck position. In several cases, this resulted in a significant increase in the intracuff pressure. For prolonged cases with the head and neck turned from the neutral position, the intracuff pressure should be measured following patient positioning to ensure that the intracuff pressure is within the clinically recommended range.

Pediatric cuffed endotracheal tubes.

Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI) scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H2O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article.

Pediatric cuffed endotracheal tubes: an evolution of care.

PURPOSE: To examine the history of pediatric endotracheal intubation and the issues surrounding the change from uncuffed endotracheal tubes to cuffed endotracheal tubes, including pediatric airway anatomy, endotracheal tube design, complications, and safety concerns. METHOD: Review of the literature. CONCLUSIONS: Although the use of cuffed endotracheal tubes in infants and children remains a topic of debate, the literature supports this change in practice. Meticulous attention must be given to intracuff pressure. Cuffed endotracheal tubes designed especially for the pediatric patient may increase the margin of safety.

Clinical Survey of Appropriate Cuff Volume and Pressure during General Anesthesia in Pediatric Patients / 대한구급학회지

BACKGROUND: Uncuffed endotracheal tubes are commonly used in pediatrics even when the risk of gastric aspiration is significant. But cuffed endotracheal tubes effectively protect the risk of pulmonary aspiration and completely seal the airway. This study was designed to determine the appropriate cuff volume and pressure with low risk of ischemic injury to children's airway. METHODS: We intubated cuffed endotracheal tube (internal diameter 4.5, 5.0, 5.5 mm) in 90 surgical pediatric patient from 16 to 118 months of age. After intubation, initial cuff volume and pressure were measured at the level of complete sealing in each group. Each group was administrated 50% nitrous oxide and 67% nitrous oxide and measured cuff pressure at 20 minutes, 40 minutes. RESULTS: 1) The mean initial cuff volume and pressure of 4.5 ID tube were 0.59 +/- 0.16 ml and 14.5 +/- 0.31 cmH2O (n=30). 2) The mean initial cuff volume and pressure of 5.0 ID tube were 1.00 +/- 0.38 ml and 14.3 +/- 3.55 cmH2O (n=30). 3) The mean initial cuff volume and pressure of 5.5 ID tube were 1.06 +/- 0.26 ml and 14.28 +/- 2.01 cmH2O (n=30). 4) The cuff pressure increased significantly in the course of time, but no pressure in three groups was above 30 cmH2O. CONCLUSIONS: We could determine the appropriate cuff volume of cuffed endotracheal tube in pediatric patients. Also we concluded that nitrous oxide concentration affect little intracuff pressure in brief operation.

Comparison of the End-Tidal PCO2 Measurements Sampled at the Distal and Proximal Ends of the Endotracheal Tube in Adults / 대한마취과학회지

To determine whether the site of gas sampling affects end-tidal gas measurements in adult patients during anesthesia, end-tidal pCO2(PetCO2) was measuredcontinuously from the distal and proximal ends of the endotracheal tube(SHERIDAN) in 33 adults ventilated with Drager anesthesia ventilator. These data were compared with simultaneous arterial PCO2 (PaCO2) measurements. The study was commenced after each patients was ventilated no less than 15 minutes at the desired ventilator settings. Gas was continuously aspirated at 230 ml/min. for measurement of the PetCO2 using SARA Cap.A.G,Capnometer'sampled from the distal and proximal ends of the endotracheal tube for 3-minutes of each sampling port, alternativiely measured at 5 minutes interval. And each measurement was repeated twice and calculated mean values. The results were as follows: The mean PetCO2 sampling from the distal end was 31.6+/-2.4 mmHg. and the proximal end was 31.0+/-2.3mmHg. The difference between two results was statistically not significant(p> 0.05). The correlation coefficients of PetCO2 vslues for the distal end and the proximal end samplings to the PaCO2 values were r =0.48 and r=0.45 respectively, and statistically significant(p< 0.05) We concluded that the measured PetCO2 sampled from the distal end of the ETCO cuffed endotracheal tube' does not show any statistically significance to the proximal one. However, distally sampled PetCO2 measurements were more approximate PaCO2 measurements than proximally sampled one.