Pierre Fayoux

Airway management in children: ultrasonography assessment of tracheal intubation in real time?

BACKGROUND: Pediatric tracheal intubation requires considerable expertise and can represent a challenge to many anesthesiologists. Confirmation of correct tracheal tube position relies on direct visualization or indirect measures, such as auscultation and capnography. These methods have varying sensitivity and specificity, especially in the infant and young child. Ultrasonography is noninvasive and is becoming more readily available to the anesthesiologist. In this study, we investigated the characteristic real-time ultrasonographic findings of the normal pediatric airway during tracheal intubation and its suitability for clinical use. METHODS: Thirty healthy children with normal airways requiring tracheal intubation were studied. Ultrasonographic measurements of the pediatric airway during tracheal intubation under deep inhaled anesthesia were performed using a Sonosite Titan® (Sonosite, Bothell, WA) scanner while recording characteristic images during this process. Correct tracheal tube placement was further confirmed using auscultation and satisfactory end-tidal capnography. RESULTS: The mean (± sd) age of studied patients was 48 ± 37 mo, weight was 19.7. ± 8.6 kg and the sex ratio (m/f) was 1:2. Successful tracheal intubation was verified using the following criteria: 1) identification of the trachea and tracheal rings, 2) visualization of vocal cords, 3) widening of glottis as the tracheal tube passes through, and 4) tracheal tube position above carina and demonstration of movement of the chest wall visceroparietal pleural interface (i.e., sliding sign) after manual ventilation of the lungs. One esophageal intubation was readily recognized by visualization of the tube in the left paratracheal space. CONCLUSION: This study describes characteristic ultrasonographic findings of the pediatric airway during tracheal intubation. It suggests that ultrasonography may be useful for airway management in children.

Prenatal and early postnatal morphogenesis and growth of human laryngotracheal structures

Advances in neonatal medicine have resulted in increased care of fetal and neonatal airways. These advances have required an exhaustive knowledge of fetal airway anatomy and development. The aim of this study was to determine the anatomical development of laryngotracheal structures during the fetal and immediate postnatal period and to correlate these observations with other fetal biometric parameters to estimate developmental particularities of the fetal airway. An anatomical prospective study was based on examination of larynx and trachea from 300 routine autopsies of fetuses and infants, free of malformation and never intubated. Anatomical measurements of cricoid cartilage, thyroid cartilage, glottis, arytenoid cartilage and trachea were performed using a precision calliper and precision divider. Statistical analysis was performed to represent the growth of anatomical structures and to evaluate the correlation with biometric data. Raw data and 10th and 90th percentile curves were fitted satisfactorily with a linear model for gestational age. A linear relationship between laryngotracheal measurement and body weight and height was observed except for glottis length, interarytenoid distance and anterior cricoid height. The diameter of the cricoid lumen was significantly less than that of the trachea and glottis lumen. A sexual dysmorphism was noted for thyroid cartilage measurements and interarytenoid distance, with measurements significantly smaller in females. This study reports the anatomical development of normal laryngotracheal structures during the fetal period. Despite the fact that this study was performed during postmortem examination, these observations can be useful to develop criteria, materials and surgical procedures adapted to fetal and neonatal airways as well as for the purposes of early diagnosis and management of laryngotracheal malformations.

Determination of endotracheal tube size in a perinatal population: an anatomical and experimental study.

Background:This study aimed at correlating anatomical dimensions of the larynx and trachea to age and weight in a prenatal population. Endotracheal tube size determination was then proposed according to these considerations. Methods:Anatomical measurements were obtained during 150 fetal and infant postmortem examinations. The optimal endotracheal tube size was determined by three methods: clinically, by a pressure method using calibrated inextensible balloons, and anatomically by comparing the laryngotracheal perimeter to the tube perimeters. Based on these results, recommended tube sizes were calculated. Results:In premature babies before 37 weeks gestation, the optimal tube size according to pressure estimation was significantly greater than that determined by anatomical measurement alone. This difference was no longer valid after 40 weeks gestation. Conclusions:This study identified the elasticity of laryngeal structures in premature babies, allowing intubation with tube sizes greater than predicted by anatomical measurements with an increasing injury risk located in the posterior part of the glottic plane. This elasticity disappears near 40 weeks gestation, and the injury risk then predominates in the subglottic region. These results lead the authors to recommend that the size of the endotracheal tube used in the perinatal population should be based on anatomical and experimental data to limit the injury risks.

Tracheal side effects following fetal endoscopic tracheal occlusion for severe congenital diaphragmatic hernia

Despite optimal neonatal care and even in large referral centres, between 20% and 30% of neonates with isolated congenital diaphragmatic hernia (CDH) will not survive [1]. The leading causes of death remain in essence pulmonary hypoplasia and persistent pulmonary hypertension (PPHT). Prenatal medical imaging methods are used to predict individual outcome, which provides parents with prenatal options. For those with a predicted poor outcome this might include prenatal intervention, which aims to improve lung development rather than repairing the anatomical defect. Early attempts by prenatal surgical repair of the defect were abandoned as they required access by hysterotomy and because reducing liver herniation compromises the fetal circulation [2]. Tracheal occlusion (TO) prevents egress of lung liquid produced by the airway epithelium, hence induces tissue stretch, which acts as a signal for lung growth [3, 4]. Clinically TO was initially performed using extra-luminal clips with reversal during an ex-utero intrapartum tracheoplasty procedure [5]. Subsequently an endoluminal balloon was used, which allows easier reversal in utero, that itself triggers lung maturation according to experimental evidence [5–7]. Invasiveness was further reduced by using a completely percutaneous approach, small diameter instruments with a move towards regional or local anaesthesia. Up to 2008 the FETO consortium performed more than 200 percutaneous fetoscopic endoluminal TOs (FETO) [8]. Survival rate is twice as high as predicted, the latter based on lung size measurements in case of left-sided CDH [9]. Obviously this data is based on external controls and the procedure should be considered as investigational whilst a trial has not confirmed these early findings [10].

Histologic Structure and Development of the Laryngeal Macula Flava

The laryngeal maculae flavae (MF) have been previously described as cellular condensations at the extremities of the vocal cords, but the exact nature and role of the MF are unknown. The purpose of this study is a histomorphological analysis of the nature and development of the MF in human vocal cords, from the beginning of fetal life to adulthood. Eighty-six larynges, from the fetus at 12 weeks of amenorrhea (WA) to adulthood, were collected from autopsies and studied by light microscopy with hematoxylin and eosin, orcein, and Alcian blue staining and pS 100 immunostaining. Our observations allowed us to separate the fetal development of the MF into 4 periods. The first corresponds to the appearance of the posterior MF between 13 and 15 WA. In the second period, the anterior MF appeared between 16 and 18 WA, allowing definition of the intermacular space. Fibrous structures, composed of collagen and elastic fibers, of the MF and intermacular space developed between 20 and 33 WA. The last period, from 33 WA to birth, corresponded to a maturation of these structures. In adults, the histologic structure of the MF presented a concentric peripheral fibrous layer associated with a central cellular component. Structural analysis of the MF concludes in favor of the chondroid nature of the macular cell. These observations bring into question the current knowledge on the MF. From these observations, the role of the MF in the developing vocal cord is discussed.

Fluoroscopic guidance of Arndt endobronchial blocker placement for single-lung ventilation in small children

Background: Thoracoscopic surgery may require single‐lung ventilation (SLV) in infants and small children. A variety of balloon‐tipped endobronchial blockers exist but the placement is technically challenging if the size of the tracheal tube does not allow the simultaneous passage of the fibreoptic scope and the endobronchial blocker. This report describes a technique for endobronchial blocker insertion using fluoroscopic guidance in children undergoing SLV.

Thyroid alar cartilage graft in laryngoplasty: anatomical study in premature and newborn babies.

The aim of this prospective anatomical study was to determine the place of the thyroid alar cartilage graft (TAC) in the laryngotracheoplasty in a population of premature and newborn babies. Ninety-eight fresh larynges, collected from autopsies, were included in the study. After measurement of cartilage dimensions and thickness, the potential dimensions of TAC and its widening capacity were calculated for each specimen. The results showed that TAC thickness was similar to the anterior cricoid arch but was significantly less than the posterior cricoid arch. The maximal degree of stenosis which could be normalized by TAC ranged between 47.8 and 74.3%. The height of the TAC allowed a widening, from the level of the glottis to the inferior part of the second tracheal ring in 100% of cases and to the inferior part of the third tracheal ring in more than 70% of cases. In conclusion, the TAC could be used for anterior grafting in laryngotracheoplasty. Its indications should be limited to grade II and a few grade III of the Myer subglottic stenosis classification without glottic or tracheal extension. Moreover, variability of TAC dimensions leads to peroperatively reassess its indication.

Airway exchange catheters use in the airway management of neonates and infants undergoing surgical treatment of laryngeal stenosis.

Background: Congenital and acquired upper airway obstruction in infants commonly manifests as an acute, potentially life-threatening condition or a slow and gradual deterioration and can be a challenge to the pediatric anesthesiologist. This case series reports the nonconventional use of pediatric airway exchange catheters emergent and short-term airway management and lung ventilation in neonates and infants with severe laryngotracheal stenosis. Case Series: After the approval of local Institutional Review Board, 11 consecutive patients presenting with severe laryngotracheal stenosis exceeding 70% were prospectively studied. Median (range) age and weight were 32 days (0–96) and 2.7 kg (2.1–3.4), respectively. Induction of anesthesia consisted of sevoflurane 5% in oxygen followed by sevoflurane 3% in an air/oxygen mixture (Fio2 = 0.5). Spontaneous ventilation was maintained in all patients. The trachea was intubated using an Airway Exchange Catheter with an inner diameter of 1.6 mm (Cook Airway Exchange Catheters, Cook Medical, Bloomington, IN). An Airway Exchange Catheter was inserted through the stenosis and manually assisted ventilation was confirmed using capnography. Median (range) ventilation duration was 28 minutes (12–61 mins). In one neonate, the Airway Exchange Catheter failed to ensure proper ventilation and an emergency tracheostomy was performed. Respiratory distress was likely due to a significant increase in airway resistance at the stenosis level or distal accumulation of secretions. Conclusion: Airway exchange catheters represent a useful additional tool for short-term advanced airway management for both oxygenation and ventilation in neonates and infants presenting with severe laryngotracheal stenosis.

Prise en charge médicale per et post-natale de la hernie congénitale du diaphragme

Resume La physiopathologie de cette malformation est complexe, et malgre les progres de la reanimation, la mortalite neonatale reste elevee proche de 30-40 % essentiellement du fait de l’hypoplasie pulmonaire et de l’hypertension arterielle pulmonaire (HTAP). Une meilleure connaissance physiopathologique est necessaire pour ameliorer la prise en charge de ces enfants. Par ailleurs, la HDC s’accompagne d’une morbidite sequellaire elevee qui touche environ la moitie des enfants vivants. Les principales sequelles observees sont respiratoires (HTAP chronique, dysplasie broncho-pulmonaire, susceptibilite aux infections virales), digestives (reflux gastro – œsophagien, trouble de l’oralite), nutritionnelles (denutrition d’origine multifactorielle : RGO, trouble de l’oralite, insuffisance respiratoire), et orthopedique (scoliose). La prise en charge actuelle de ces complications est tardive : elle necessite une intervention plus precoce, qui doit debuter des la periode neonatale. Elle necessite imperativement un suivi et une prise en charge multidisciplinaire specialisee du fait de l’intrication de ces differentes complications. Ainsi, les objectifs de la prise en charge en periode neonatale sont de reduire la mortalite immediate, essentiellement liee a un echec de l’adaptation a la vie extra-uterine, mais aussi de mettre en place, des la naissance, des mesures de prevention de la morbidite a long terme.Congenital diaphragmatic hernia (CDH) is a 1 out of 3500 live-born malformation with persistent 30-40% mortality rate, related to severe pulmonary hypoplasia and hypertension. Better knowledge on the mechanisms inducing failure of adaptation at birth is a prerequisite for improving CDH prognosis. CDH is also associated with longterm morbidity, including prolonged respiratory failure, failure to growth, oral aversion, and scoliosis. Early prevention starting as soon as the first hours of life are required to reduced long term morbidity. The aims of the management are not only to reduce early mortality, related to persistent pulmonary hypertension, but also to prevent late morbidity.

Distances from vocal cords to mid-trachea for optimizing endotracheal tubes depth markers according to gestational age.

Adequate endotracheal tube positioning in preterm infants is complicated by the short length of the airway. Distal markers were designed to help with the insertion of endotracheal tubes at an appropriate depth below the vocal cords. However, those markers are not standardized between manufacturers, each tube size displays only one (sometimes 2) markers to provide information for infants of various gestational ages, and indicated distances are often too long for extremely preterm infants.