Continuous Monitoring of Dynamic Pulmonary Compliance Enables Detection of Endobronchial Intubation in Infants and Children

Effects of individualised lung-protective ventilation with lung dynamic compliance-guided positive end-expiratory pressure titration on postoperative pulmonary complications of paediatric video-assisted thoracoscopic surgery: protocol for a randomised controlled trial

INTRODUCTION

Lung-protective ventilation strategies (LPVS) for one-lung ventilation (OLV) in paediatric patients pose greater challenges than in adults. Optimising LPVS for paediatric OLV to mitigate postoperative pulmonary complications (PPCs) has emerged as a current research focal point. However, there remains a divergence of opinions concerning the individualised setting and application of positive end-expiratory pressure (PEEP). Lung dynamic compliance (Cdyn) can serve as a reflection of the lung's physiological state in children during OLV and is a readily obtainable parameter. This study protocol is formulated to assess the effectiveness of Cdyn-guided PEEP titration on PPCs during paediatric OLV.

METHODS AND ANALYSIS

This study constitutes a single-centre, prospective, double-blind, randomised controlled trial. The trial aims to recruit 60 paediatric patients scheduled for video-assisted thoracoscopic surgery. These eligible patients will be randomly assigned to either the Cdyn-guided PEEP group or the conventional PEEP group during general anaesthesia for OLV. The primary outcome will involve assessing the incidence of PPCs at 7 days after surgery. Secondary outcomes will encompass the evaluation of the modified lung ultrasound score following surgery, as well as monitoring the oxygenation index, driving pressure and Cdyn during mechanical ventilation. Data collection will be performed by investigators who are kept blinded to the interventions.

ETHICS AND DISSEMINATION

The Clinical Trial Ethics Committee at Shenzhen Children's Hospital has conferred ethical approvals for this trial (approval number: 2022076). Results from this trial will be disseminated in peer-reviewed journals and presented at professional symposiums.

TRAIL REGISTRATION NUMBER

NCT05386901.

A new formula to predict the size and insertion depth of cuffed nasotracheal tube in children receiving dental surgery: a retrospective study

This retrospective study aimed to develop a new formula for selecting the appropriate size and determining the depth of the cuffed nasotracheal intubation (NTI) for a cuffed endotracheal tube (cETT) in pediatric patients undergoing dental surgery. In addition, the clinical data on cETT (i.e., the size and depth of insertion) was compared with those calculated with age-based formulas to evaluate their correlation. A total number of 684 patients who received NTI were enrolled (healthy group, n = 607; special-need group, n = 77). The ETT size used in real-world scenarios was smaller (i.e., about 0.5 and 0.94 mm) than the age-based formula, while the ETT depth was greater (i.e., about 1.5 cm) than the age-based formula in both groups. In the healthy group, age, gender, and body weight were identified as predictors of ETT size and depth through multiple linear regression analysis, while only age and body weight were predictors in the special-needs group. New formulas were developed based on these findings, with ETT size = 3.98 + 0.052 × age + 0.048 × gender (male = 1, female = 0) + 0.023 × body weight (kg) and ETT depth = 15.1 + 0.43 × age + 0.300 × gender (male = 1, female = 0) + 0.007 × body weight (kg). The new formula could be useful for both healthy and special-need pediatric populations undergoing dental procedures.

Comparison of clinical methods to diagnose pediatric endobronchial intubation-A randomized controlled trial

Background and Aims:

Diagnosing accurate placement of the tip of the endotracheal tube is crucial in pediatric practice. This study was conducted to find out the efficacy of five clinical methods to ascertain the tube position by a resident anesthesiologist.

Material and Methods:

This was a randomized crossover study conducted in a research institute. Fifty pediatric patients were enrolled. All patients were randomly allocated to tracheal (group T) or bronchial group (group B). The five clinical methods which were evaluated include the auscultation, observation of chest movements, bag compliance, tube depth, and capnography. In group T, the tube was placed in the trachea and later positioned in bronchus (assisted by fiberoptic bronchoscopy). The vice versa was done in group B. In each position, a single test followed by all tests was performed and after the change of position, the same single test followed by all tests was performed. Correct and incorrect diagnoses by tests in detecting tube positions were made and their sensitivity and odds ratio were estimated.

Results:

The tube depth and combination of all tests detected endobronchial intubation with a sensitivity of 88% and 97%, respectively, which is more than that of auscultation (70%) and observation (55%). Evaluation of the difference in agreement level of tube depth to detect tube-position showed the odds ratio of 2.28 (0.17–30.95) for detecting endobronchial intubation.

Conclusion:

We observed that the tube-depth was better than the other individual tests in diagnosing endobronchial intubation in pediatric patients. However, its efficacy is lesser than that of performing all clinical tests together.

Factors affecting airway compliance and resistance in children receiving general anesthesia during adenotonsillectomy

Airway compliance is an important index in the surgery of pediatric patients. This study aimed to explore factors affecting dynamic airway compliance (Cdyn) and airway resistance (Raw) after general anesthesia endotracheal intubation for adenotonsillectomy of pediatric patients.A prospective study was undertaken of 107 children who underwent adenotonsillectomy in Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine between January and June 2018. The values of Cdyn and Raw were recorded at 5, 10, and 15 minute during general anesthesia endotracheal intubation. Univariate analysis and multiple linear regression analysis were performed for factors that affected Cdyn and Raw.Of the 107 patients aged 56.67 ± 18.28 months, 69 (64%) patients were male, and 26 (24%) and 12 (11%) had an upper respiratory infection in the past week and 1 to 2 weeks, respectively. During anesthesia, Cdyn showed a decreasing trend (P < .001) while Raw showed an increasing trend (P < .001). Multivariate analysis revealed that height (β=0.177-0.193) had the strongest correlation with Cdyn; rales during pulmonary auscultation (β= -2.727 to -1.363) and sputum suction (β= -1.670 to -0.949) were also associated with Cdyn (all P < .05). Height was the factor with the strongest negative correlation with Raw (β= -0.382 to -0.305). Rales during pulmonary auscultation (β=10.063-11.326) and sputum suction (β=3.863-9.003) were also associated with Raw (All P < .05).Height, rales during preoperative auscultation and sputum suction were all associated with intraoperative Cydn and Raw for pediatric patients undergoing adenotonsillectomy and should be considered before the surgery.

Detection of intratracheal accumulation of thick secretions by using continuous monitoring of respiratory acoustic spectrum: a preliminary analysis

The accumulation of tracheobronchial secretions may contribute to a deterioration in pulmonary function and its early detection is important. In this study, we analyzed the respiratory sound spectrum in patients with intratracheal secretion, and compared acoustic characteristics before and after therapeutic endotracheal suctioning. After review of anesthetic records of liver transplant recipients, we included recipients with identified intratracheal secretion during surgery. Intraoperative breath sounds recorded through esophageal stethoscope were sampled in 20 s-period before and after suctioning of secretion and analyzed using fast Fourier transform. We also analyzed normal breath sounds from recipients without any respiratory problem as control group. The maximal power (dBm_Max), total power from whole frequency range of 80-500 Hz (P_t), total power of each frequency range (80-200 Hz, P_80-200; 200-300 Hz, P_200-300; 300-400 Hz, P_300-400; 400-500 Hz, P_400-500), and their ratio (P_80-200/P_t, P_200-300/P_t, P_300-400/P_t, P_400-500/P_t) were compared. Breath sounds were obtained from 20 recipients; 9 pairs of breath sound before and after suctioning of secretion and 11 normal breath sounds. Patients with intratracheal secretion showed significantly higher P_80-200, P_200-300, P_300-400, P_400-500 when compared to the those of normal control patients (P = 0.003, P = 0.002, and P = 0.009, respectively), while dBm_Max did not differ. Elimination of secretions attenuated P_80-200, P_200-300, P_300-400, and P_400-500 by 22.4%, 25.7%, 48.5%, and 15.3%, respectively (P = 0.002, 0.024, 0.009, and 0.016, respectively). Identifying the presence of intratracheal secretions with power ratio at 80-200 Hz and 300-400 Hz showed the highest area under the curve of 0.955 in receiver operating characteristic curve analysis. We suggest that spectral analysis of breath sounds obtained from the esophageal stethoscope might be a useful non-invasive respiratory monitor for accumulation of intratracheal secretion. Further prospective studies to evaluate the utility of acoustic analysis in surgical patients are warranted.

Subglottal resonances of American English speaking children

This paper presents an investigation of children's subglottal resonances (SGRs), the natural frequencies of the tracheo-bronchial acoustic system. A total of 43 children (31 male, 12 female) aged between 6 and 18 yr were recorded. Both microphone signals of various consonant-vowel-consonant words and subglottal accelerometer signals of the sustained vowel /ɑ/ were recorded for each of the children, along with age and standing height. The first three SGRs of each child were measured from the sustained vowel subglottal accelerometer signals. A model relating SGRs to standing height was developed based on the quarter-wavelength resonator model, previously developed for adult SGRs and heights. Based on difficulties in predicting the higher SGR values for the younger children, the model of the third SGR was refined to account for frequency-dependent acoustic lengths of the tracheo-bronchial system. This updated model more accurately estimates both adult and child SGRs based on their heights. These results indicate the importance of considering frequency-dependent acoustic lengths of the subglottal system.

Unrecognized bronchial intubation associated with the uncuffed pediatric tracheal tube with bilateral Murphy eyes

BACKGROUND

Unreliability of breath sounds auscultation after intubation is reportedly mainly related to the presence of the Murphy eye. This study was performed to ascertain whether an uncuffed pediatric tracheal tube with bilateral Murphy eyes increases the risk of unrecognized bronchial intubation, compared to an uncuffed tube without eyes.

METHODS

Following induction of anesthesia in 50 toddlers, either an uncuffed tube without eyes or an uncuffed tube with bilateral eyes was inserted into the trachea. The tube was then slowly advanced while breath sounds were auscultated using a stethoscope. In study 1, when breath sounds changed and disappeared, the distance from the carina to the tube tip was measured using a fiberoptic bronchoscope. In study 2, when breath sounds changed, the tracheal tube was withdrawn 5, 10, 15 and 20 mm while using a fiberoptic bronchoscope to ascertain whether bronchial intubation had occurred.

RESULTS

When breath sounds changed and disappeared, the tip of the tube with bilateral eyes was positioned more deeply below the carina than that of the tube without eyes. When the tube was withdrawn 10 mm from the point at which breath sounds changed, frequencies of bronchial intubation were 13% and 80% in the no eyes and double eyes groups, respectively.

CONCLUSION

An uncuffed pediatric tracheal tube with bilateral Murphy eyes reduces the ability of breath sounds auscultation to detect bronchial intubation and may increase the risk of unrecognized bronchial intubation compared to an uncuffed tube without eyes.

Magnetic endotracheal tube imaging device

This paper describes an accurate, economical, and portable device that helps to locate the position of an endotracheal tube (ETT) in situ. The device uses an array of magnetic field sensors to detect an anomaly in magnetic field caused by magnet embedded near the cuff of an ETT, and displays an intuitive map of relative magnetic field intensity under the sensor area. The device provides real-time feedback of the position to a clinician, so that corrective measures can be taken if the ETT is determined to be outside of normal positioning with respect to the patient's airway. Variations of the proposed design are suitable for continuous monitoring.