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Pediatric upper airway and congenital anomalies
Abstract
Understanding the differences between the infant upper airway and the adult upper airway is important in properly managing the infant and pediatric airway. Proper history and physical examination and selection of the appropriate endotracheal tubes, LMAs, and laryngoscopes are key to managing the normal infant and pediatric airway. The difficult infant and pediatric airway requires planning, preparation, and teamwork. The LMA, the light wand, and fiberoptic bronchoscope are important tools for managing the difficult pediatric airway. Congenital syndromes associated with difficult airways pose a unique set of challenges. Postoperative problems include postextubation croup and obstructive sleep apnea. Extubating the infant or child with a difficult airway should be orchestrated as carefully as intubating the infant or child with a difficult airway.
... The kind of confluence of airway abnormalities witnessed in this case was never reported in any syndrome. [1][2][3][4] The karyotyping was found to be normal, with no mutations specific to Cornelia de Lange syndrome. As reported earlier, 30% of the patients with Cornelia de Lange syndrome might have normal karyotyping, the present case revolves around 2 possibilities: a new syndrome yet to be reported or a new variant of Cornelia de Lange sequence yet to reveal itself. ...
... Sir, The ultrasound-guided thoracolumbar interfascial plane (TLIP) block, which can be used for the analgesia for patients undergoing lumbar vertebra surgery, was first reported in 2015. [1] The injection of local anesthetic (LA) into the fascial plane between the multifidus and longissimus muscles at the level of the third lumbar vertebra (L3) can block the adjacent dorsal rami of the spinal nerves. As a new technology, its indications and contraindications have not been clearly defined. ...
... La instrumentación de la VA durante el período perioperatorio es un estímulo importante que puede producir laringoespasmo o broncoconstricción. En los lactantes predomina el sistema nervioso parasimpático; la bradicardia es la principal respuesta a la hipoxemia (45). Son precisamente estas diferencias anatomofisiológicas y la falta de cooperación del paciente pediátrico, lo que hacen que las medidas de valoración de VA que se utilizan en los adultos no sean extrapolables a los niños. ...
... Pero si la decisión es aplicar relajación neuromuscular la ventaja es: condiciones óptimas para IT; y las desventaja: colapso de la VA, rápida desaturación, incapacidad para ventilar con MF, e insuflación de estómago. La ketamina permite mantener ventilación espontanea con la advertencia de que aumenta la producción de secreciones orales, con la posibilidad de producir laringoespasmo, excepto que se combine con atropina (45). ...
There is a wide variety of diseases throughout the life of an individual, which invariably impact on moments such as tracheal intubation, and which increase morbidity by anesthesia. There is no accurate predictive index to 100% for tracheal intubation, predictive indexes of difficult intubation are varied, and there are a lot of them, so they are only important airway management guidelines, although they can be approximated to the reality of life quite successfully however their failures or drastic changes, for example in the obstetric patient, where a score of a scale can change quickly during the stay in the work, in only a few hours. This has given origin to a large number of scales described in world literature. By contrast in an older child the pediatric airway is more challenging than in an adult, although the airway advance is not uncommon. The most frequent cause of mortality in children is hypoxia, most common in the newborn and infant that in an older child, this is due to increased consumption of oxygen and a poor reserve of the same. Failures to recognize complicated airway in the newborn are frequent and are usually of congenital origin, a few are from acquired type. The majority of adult airway devices have been applied in children with considerable success.
... When compared to adults, the ratio of tongue/mouth cavity is greater in infants and young children. Furthermore, the epiglottis in children has an posterior angulation and is bulkier and less flexible than in adults [7]. ...
Congenital tracheal disorders are a heterogeneous group of pathologies characterized by noisy breathing and abnormal compressibility of the main airway. They encompass a wide variety of abnormalities and can differ in prevalence and/or incidence. Congenital tracheal abnormalities can present as impaired/abnormal cartilage development, or as extrinsic compression from other thoracic/gastrointestinal organs; they can also be classified as static or dynamic anomalies [1, 2]. While some of them may not warrant an urgent medical visit, others may acutely effect a child’s life, potentially causing airway obstruction, impairment of ventilation, respiratory distress, or cerebral hypoxia and requiring emergent management.
... Pediatric patients have some anatomical and physiological differences compared to adults. The larynx level, tongue to mouth ratio, epiglottis angle, and size are more pronounced in babies and these Otorhinolaryngology differences decrease as the child grows [8]. Because of these differences, mask ventilation, direct laryngoscopy and endotracheal intubation are relatively more difficult in pediatric patients than in adults. ...
... 4 The characteristic facial features of DS patients, which include mid-face hypoplasia, macroglossia, micrognathia, high-arched palate, poor dentition, and small upper airway, [13][14][15] predispose these patients to obstructive sleep apnea (OSA); there is an 85% prevalence of OSA among DS adults, with a mean apnea-hypopnea index of 25. 3 Additionally, airway management can be difficult and these patients may have laryngotracheal or subglottic stenosis. 16,17 While subglottic stenosis is commonly associated with children with DS, its frequency in adults is unclear. Dental lesions are frequently encountered in DS children, as well as respiratory infections. ...
Because of enhanced life expectancy due to medical and surgical therapeutic advances, it is estimated that there are more adults than children living with Down syndrome (DS), or trisomy 21, in the United States. Therefore, DS can no longer be considered a syndrome limited to the pediatric population. These patients are presenting for surgery and anesthesia in adult care settings, where anesthesiologists will encounter these patients more frequently. As these patients age, their commonly associated co-morbidities not only progress, but they also develop other cardiac, respiratory, gastrointestinal, and neurologic conditions. The manifestations and consequences of chronic disease can present new challenges for the anesthesiologist and require expertise and judgement to minimize patient risk. The purpose of this narrative review is to describe the common pediatric co-morbidities associated with DS and discuss the age-acquired manifestations. Additionally, considerations for anesthetic care of the adult with DS will be presented, including the preoperative assessment, intraoperative management, and postoperative care.
... Sir, The ultrasound-guided thoracolumbar interfascial plane (TLIP) block, which can be used for the analgesia for patients undergoing lumbar vertebra surgery, was first reported in 2015. [1] The injection of local anesthetic (LA) into the fascial plane between the multifidus and longissimus muscles at the level of the third lumbar vertebra (L3) can block the adjacent dorsal rami of the spinal nerves. As a new technology, its indications and contraindications have not been clearly defined. ...
... Bedside Procedures could make difficult to achieve ETI. Among the anatomical factors related with DA are the form and size of mouth, nose, mandible, neck, existence of masses or congenital malformations, and other childhood diseases that eventually could difficult ETI (Figure 12, Tables 3 and 4) [20][21][22][23][24]. ...
... Congenital airway abnormalities include structural changes in the upper or lower respiratory tract. Upper airway abnormalities may be diagnosed as a result of stridor, respiratory distress, or failure to thrive [8,9]. The extant literature on 22q11.2DS ...
Introduction:
22q11.2 deletion syndrome (22q11.2DS) presents with complex but variable symptoms, including cardiac, immune, palatal, endocrine, cognitive, and psychiatric issues. However, an association of 22q11.2DS with structural airway abnormalities has not been formally described. The aim of this study was to document the frequency of this association.
Methods:
We retrospectively reviewed medical records of patients with 22q11.2DS evaluated in the 22q and You Center at the Children's Hospital of Philadelphia between 1999 and 2015 referred to otolaryngology for an airway assessment. Type of airway abnormality and presence of comorbidities, such as congenital heart disease, tracheostomy, and association with prenatal symptomatology such as polyhydramnios, were noted.
Results:
Of the 104 patients who underwent an otolaryngology procedure (microlaryngoscopy or bronchoscopy), 71% (n = 74) had airway abnormalities. Patients with airway abnormalities ranged in age from 5 months to 37 years, with similar prevalence among males and females. Observed airway abnormalities included tracheomalacia (36%), subglottic stenosis (28%), laryngomalacia (26%), glottic web (21%), and bronchomalacia (16%). Most patients with airway abnormalities (91%) had an associated congenital heart defect, with ventricular septal defect and Tetralogy of Fallot being the most prevalent. Importantly, 30% of patients required a tracheostomy, and overall polyhydramnios was noted in 16% of pregnancies.
Conclusion:
Airway abnormalities are a common feature of 22q11.2DS, leading to substantial morbidity, particularly when combined with complex cardiac disease. Polyhydramnios may be an important prenatal clue to both the diagnosis of 22q11.2DS and airway anomalies. Postnatal assessment of airway structure and function among patients with 22q11.2DS is an important component of overall evaluation and will help guide long-term management.
The pediatric larynx has the following definitive characteristics: the larynx in children is higher than in adults;the larynx is small and narrow as an airway; the epiglottis is soft and omega-shaped; and the aryepiglottic folds are shorter. Of the morphological features of the pediatric larynx, in this study we examined the morphology of the epiglottis and the length of the aryepiglottic folds retrospectively using flexible nasolaryngoscopic videos. The subjects were 282 patients generally treated as children and under 15 years of age during the 5-year period from May 2017 to April 2022, who visited our department of otorhinolaryngology. Of the 282 patients, 105 (37.2%) were found to have the omega-shaped epiglottis, and in neonates, infants, and pre-school children, it was found in one-third to one-half of the patients. A flat epiglottis similar to the epiglottis in adults was found not only in schoolchildren but also in neonates and infants. The morphology of the epiglottis was not significantly different between genders, but age and the presence of underlying disease resulted in significant differences. These findings suggested that the length of the aryepiglottic folds may serve as a subjective means of evaluation. The omega-shaped epiglottis was observed using an indirect laryngoscope. It is difficult to get a clear view and understand the laryngeal features using a flexible nasolaryngoscope. We believe it is easier to understand the epiglottis's omega shape if it is described together with the curled epiglottis.
It was not until a few decades ago, that the metaphor of “children being not little adults” being recognized by the world. Since then, medical professionals understood that pediatric practice is not simply extrapolations from adult medical practices. These differences arise due to various reasons including the dynamic developmental anatomy and physiology of children, relative or actual immaturity of organ systems, different and unique environmental hazards they are exposed to and their inability to communicate. Safe airway management in neonates require both technical skills and understanding of the neonatal anatomy and physiology. This chapter deals with the approach, techniques and complications of neonatal airway management in the context of their unique nature.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Emergent obstetric deliveries may present the anesthesiologist with a unique challenge of managing the airway of previously undiagnosed syndromic or malformed newborns in the obstetric theatre. The present report describes an emergency cesarean section in a 32-year-old lady who delivered a newborn with grossly anomalous features, the challenges in airway management in the newborn, and a discussion on preparation and sensitization about encountering such scenarios for the anesthesiologist and the associated medical teams.
Proper airway management is vitally important to ensure adequate oxygenation and ventilation in a patient; without it, death, brain injury, and cardiopulmonary compromise can quickly ensue. Whether a patient receives general anesthesia—in which normal airway reflexes are deliberately suppressed in a controlled fashion—or intravenous sedatives that depress normal respirations in a dose-dependent manner, it is paramount to understand the anatomic abnormalities that can affect management of the airway. This chapter will examine features of both the normal and abnormal airway; highlight the nature of airway anomalies found in common pediatric and adult syndromes; discuss components of a comprehensive airway examination; and describe the airway management for these patients. A thorough understanding of proper airway assessment can go a long way in minimizing the morbidity and mortality that can result from inadequate oxygenation and ventilation.
Klippel‐Feil syndrome (KFS) is a rare congenital cause of a difficult airway. It is a progressive disorder but there is no publishd literature describing the on‐going deterioration of the condition, particularly with regard to airway management.
We describe multiple airway management episodes in a male with KFS, noting how quickly the airway deteriorates as the patient grew older within a short time frame of 2 years. The anaesthetist must understand and be prepared for a situation where airway management that was successful previously may fail subsequently.
Background:
The use of a shoulder roll to view the glottic opening during direct laryngoscopy in infants has been recommended but is not evidence based.
Methods:
Twenty infants with normal airways, <6 months of age undergoing elective surgery under general anesthesia were randomized to undergo direct laryngoscopy first with a 2-inch vertical shoulder roll and then without, or vice versa. The primary outcome was the difference in the vertical distance between the angle of the laryngoscopist's eye and the operating room table in the 2 positions. Also, the views of the glottic opening in both positions were recorded for each infant and analyzed by a blinded investigator using the percent of glottic opening (POGO).
Results:
Twenty infants completed the study without complications. The vertical distance did not differ significantly whether the shoulder roll was placed first or second, and there was no evidence of a differential carryover effect in the crossover design (P = .268). The main effect of the shoulder roll on the mean (95% confidence interval [CI]) vertical distances without 47.8 cm (43.5-52.1) and with the shoulder roll 37.2 cm (33.3-41) yielded a mean (95% CI) vertical difference of 10.6 cm (9.3-11.79; P = .0001). The median (interquartile range [IQR]) POGO scores without 100 [86.2, 100] and with the shoulder roll 97.5 [80, 100] did not differ (median difference [95% CI]:0 [-20 to 0] P = .39).
Conclusions:
A 2-inch shoulder roll lowers the line of sight of the glottic opening compared with no shoulder roll, without affecting the view of the glottic opening during laryngoscopy in infants.
General anesthesia has allowed surgeons to correct disfiguring lesions in infants and children since the introduction of anesthesia in the middle of the 19th century. This chapter focuses on the anesthetic challenges encountered in major craniofacial reconstruction, including cleft lip and palate repair. Various genetic and environmental factors cause anomalous craniofacial development. The etiology of craniofacial syndromes and craniosynostosis is heterogeneous and multifactorial. Craniosynostosis, or premature closure of the cranial sutures, restricts skull growth in the affected region. Single suture synostosis leads to characteristic skull deformities as growth is inhibited in the synostotic suture and compensated by increased skull expansion in non‐affected areas. The Pierre Robin sequence is a well‐defined subgroup of the cleft lip and/or palate population with an unknown etiology of the branchial arch. Cleft lip and/or palate are the most frequent congenital craniofacial malformations.
Mucopolysaccharidoses (MPS) are genetically determined diseases, leading to a deficiency of enzymes in the glycosaminoglycan (GAG) degradation pathway. The accumulation of GAG occurs in connective tissue in various organs and systems of the body, including the larynx, trachea, and bronchi. Respiratory symptoms are common and severe in these patients, and respiratory disease is a frequent cause of death. A cross-sectional study with flexible bronchoscopy was conducted in 30 MPS patients (6 MPS I, 8 MPS II, 2 MPS III, 3 MPS IV-A, and 11 MPS VI). Only four patients (13.33%) had a normal airway; nine (30%) had mild to moderate disease, 12 (40%) moderate to severe, and five patients (16.67%) had severe disease. Of particular interest, neuronopathic MPS II had the largest proportion of tracheostomized patients who died due to respiratory complications; in MPS IV-A, all patients had significant tracheobronchial deformity with associated tracheomalacia, despite lacking laryngeal involvement. Laryngotracheobronchial disease (LTBD) was associated to longer disease history and was significantly more severe in older patients. Longer use of enzyme replacement therapy did not prevent the progression of LTBD, although the age of therapy introduction may be a crucial factor in lower airway involvement.
Management of the Difficult Pediatric Airway - edited by Narasimhan Jagannathan September 2019
Managing the airway of an infant with Pierre Robin sequence (PRS) is particularly challenging for anesthesiologists. Patients with PRS have the triad of micrognathia, glossoptosis, and airway obstruction that potentially and frequently leads to difficulty with both ventilation and intubation. Thus continuous oxygenation and spontaneous ventilation during intubation are essential. We describe a new method to deliver continuous oxygen and volatile anesthetic during nasotracheal intubation in an infant with PRS.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Introduction Writing a short chapter on ENT emergencies (Table 8.1) is seemingly oxymoronic given that the topic could easily be the subject of entire textbooks. This fact notwithstanding, it is the intent of this chapter to offer a brief overview of otolaryngologic emergencies, covering the topic in broad strokes. In this sense the chapter can be envisioned as an overview that links to more detailed discussions in more specialized chapters to follow. Equipment A special effort should be made to ensure adequate preparation for ENT emergencies [1], especially in terms of airway equipment (Table 8.2). In addition to these airway gadgets and unlisted items favored by individual practitioners, ENT surgeons will want ready access to an emergency tracheotomy tray as well as to some form of suspension laryngoscope or rigid bronchoscope (see Chapter 2). Special attention to the maintenance and cleaning of fiberoptic bronchoscopes is also important given that they must always be easily accessible and reliable when needed. In the case of electronic fiberscopes incorporating a video display, establishing that illumination settings and white balancing have been done correctly prior to use is particularly important.
Introduction The first public demonstration of ether on October 16, 1846 was administered for ENT surgery. Dr. William Morton anesthetized patient Edward Gilbert Abbott for removal of a tumor from Abbott’s neck by Dr. John Warren [1]. Since then, significant advances in both ENT anesthesia and ENT surgery have been made. The relationship between ENT anesthesia and ENT surgery has never been stronger than it is today, and there is probably no other subspecialty of anesthesia that has such close ties with a subspecialty of surgery. ENT surgical procedures require that anesthesiologists share the airway with the ENT surgeons. A good ENT anesthesiologist should not only understand the condition of the patient preoperatively, but should also be able to anticipate the effects of surgery on the patient. Traditionally, ENT operations consist of relatively short procedures, ranging from tonsillectomies, to tympanostomies, to tracheostomies. However, some of the most dreaded anesthesia tragedies occur in this setting. For instance, Bishop documented that anesthesia-related intraoperative death accompanying tonsillectomy and adenoidectomy ranged from 12% to 17% of the entire intraoperative mortality during the 1920s and 1930s in the United States [2]. Both anesthesiologists and surgeons should realize that nothing is trivial just because the procedure is small and short. Improvements in both anesthesia and surgery have been made to ensure the safety of the patients.
Introduction Over the past decade, the role of anesthesiologist during tracheotomies has evolved. Though surgical tracheotomies performed in the operating room are the norm, there is a growing trend of performing bedside percutaneous dilatational tracheotomies in the intensive care unit. For anesthesiologists the provision of care for patients undergoing tracheotomies in the operating room is a routine matter; however, with published studies finding decreased morbidity with bedside-performed percutaneous dilatational tracheotomies, anesthesiologists are challenged outside their comfort zone in the traditional operating rooms to support surgeons at the bedside in the ICU, thus adding another so-called "remote anesthesia service location". Furthermore, some intensive-care-trained anesthesiologists are opting to perform their own patients’ percutaneous tracheotomies, which blurs the boundaries between a surgeon’s role and that of the intensivist anesthesiologist. The cricothyrotomy and the tracheotomy are both procedures that create a subglottic surgical airway. A cricothyrotomy is an emergency procedure that is performed with a stab incision through the cricothyroid membrane, whereas a tracheotomy usually requires a more meticulous and lengthy dissection of the neck tissues before entering the trachea between the second and third tracheal rings. Therefore most tracheotomies are performed in a more controlled environment and are considered elective or urgent procedures.
Introduction Septoplasty and rhinoplasty are both commonly performed surgical procedures. Most of these procedures are performed on an outpatient basis, often in a free-standing surgical facility. Septoplasty surgery can be performed to relieve symptoms of nasal obstruction or as a component of rhinoplasty surgery. Often, it is combined with turbinate reduction surgery. Patients with obstructive sleep apnea (OSA) may undergo septoplasty to facilitate use of continuous positive airway pressure (CPAP). Rhinoplasty surgery is performed for cosmetic or reconstructive purposes to alter the appearance of the nose. The indication for surgery may be purely cosmetic, post trauma, reconstructive after tumor resection or to improve nasal breathing. Anesthetic managementPreoperative management A patient presenting for rhinoplasty or septoplasty should have a preoperative workup directed by their preexisting medical conditions. Most patients presenting for septoplasty are young and healthy but some may have OSA. Older patients may present for reconstruction of their nose following basal cell carcinoma resection and may have significant comorbidities owing to their age. Additional testing should be directed by their history and physical exam.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
The maxilla Introduction Surgery of the maxilla straddles the expertise of otorhinolaryngology and oromaxillofacial surgeons. This section of the chapter will focus on non-traumatic maxillary procedures and endoscopic maxillary sinus surgery. The maxilla is composed of two fused bones along the palatal fissure that form the upper jaw. The body of the maxilla is a component of three cavities - the roof of the mouth, the wall of the orbit and the floor and lateral wall of the nasal antrum. The maxillary sinus is housed in the body of the maxilla and is the largest of the paranasal sinuses [1]. Surgical procedure Maxillectomy surgery may encompass many variations - total maxillectomy with and without orbital exenteration, partial (subtotal) maxillectomy and limited maxillectomy. Limited maxillectomy is defined as surgery that removes one wall of the antrum. An example of a limited maxillectomy is a medial maxillectomy. Subtotal maxillectomy is defined as removal of two walls of the antrum. Total maxillectomy is defined as removal of the total maxilla [2]. Indications for maxillectomy include tumors of the palate, nasal cavity and sinus pathology, salivary gland pathology, fungal infection (mucormycosis), papilloma, angiofibroma and granulomatous disease. A maxillectomy may also be performed for skull base pathology [3]. Benefits of endoscopic maxillectomy include access to ethmoid and sphenoid sinuses, no external scarring, and no loss of bony nasal or anterior maxillary support structures [4].
Introduction An airway fire is potentially deadly complication that may occur during tracheotomy surgery, during laser surgery and with a number of other procedures [1-4]. The objective of this chapter is to introduce readers to the prevention and management of airway fires. The discussion includes the American Society of Anesthesiologists Operating Room Fire Algorithm (Figure 11.1), a checklist-like protocol for dealing with airway fires (Table 11.1) as well as some British recommendations specific to tracheotomy surgery (Table 11.2). Operating room fires are best divided into airway fires and non-airway fires. A recent report by the American Society of Anesthesiologists provides specific guidance for both these scenarios (Figure 11.1). Some safety principles Several principles apply to reduce the chance of fires in the settings of ENT surgery. Preventive measures do not guarantee that fires will not occur; always be prepared. Know the ASA algorithm for operating room fires. A simple means to extinguish airway fires (e.g., 50 ml syringe filled with saline) should be immediately on hand. In addition, a CO2 fire extinguisher is good to have nearby. The surgeon should avoid entering the trachea using electrocautery. The anesthesiologist must maintain special vigilance at the moment of surgical entry into the trachea. The anesthesiologist should keep the administered oxygen levels to the minimum needed when a significant potential for an airway fire is present. Nitrous oxide should not be used during airway surgery, since it supports combustion just as does oxygen.
Introduction Face transplantation (Figure 23.1) remains a very rare procedure. Only about 15 cases, including total and partial face transplantation, have been done worldwide at the time of writing this chapter. Each procedure has been unique with respect to indications and the nature and extent of the transplanted tissue. There has been one case report detailing the anesthesia management during face transplantation in the setting of coagulopathy [1]. However, there has been no systematic description of the anesthesia management for face transplantation. This chapter will outline anesthetic considerations for this unique and complex procedure based on the experience of two hospitals where the first face transplants in the United States took place as well as preliminary data from three international centers (personal communication). Management of the donor during face tissue and multiorgan harvest The details of anesthetic care for the multiorgan donor has been outlined in the literature [2-5]. Similar principles to conventional organ procurement apply, however, when consideration is given to the harvest of a composite facial graft, one has to keep in mind that due to the surgical complexity and long duration of procurement, harvesting of the facial graft should ordinarily be performed before other organs are retrieved. Maintenance of adequate tissue perfusion and donor hemodynamic stability during this long procurement period can have a significant impact on the quality of the graft and organs to be procured later [6].
Introduction This chapter is concerned with difficult airway management in the context of otolaryngologic surgery. (A related chapter, Chapter 9, is concerned with some specific otolaryngologic tumors and infections.) While the focus here is on otolaryngologic surgery, most of the principles discussed herein apply to clinical airway management in general, regardless of the surgical procedure. In particular, the American Society of Anesthesiologists’ difficult airway algorithm (or similar algorithm), briefly outlined in this chapter and shown in Figure 4.1, should ordinarily be a starting point for nearly all aspects of clinical airway management. To a large extent, the airway management technique for otolaryngologic surgery will depend on clinical circumstances (Table 4.1) as well as the airway management skills of the anesthesiologist and the available equipment (Tables 4.2 and 4.3). The following general options exist: (1) general endotracheal anesthesia, (2) general anesthesia using a supraglottic airway device such as a laryngeal mask airway, (3) general anesthesia using an ENT laryngoscope (to expose the airway) in conjunction with jet ventilation, (4) employing intermittent apnea, (5) general anesthesia using the patient’s natural airway, with or without adjuncts such as jaw-positioning devices or nasopharyngeal airways, and (6) local anesthesia in conjunction with IV sedation in some form, with the patient breathing spontaneously. The first option is doubtless the most popular, but the technique chosen, as well as the method of implementing the technique chosen, will depend on factors such as the perceived difficulty of intubating the patient using ordinary methods. Evaluation of the airway in this particular respect is discussed elsewhere in this book (Chapters 3 and 5).
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Introduction Anesthesia for pediatric otorhinolaryngologic procedures represents the largest proportion of elective surgery for not only pediatric anesthesiologists but also general anesthesiologists taking care of children. Anesthesia for otologic proceduresMyringotomy Chronic otitis media with effusion (COME) is common in young children secondary to impaired eustachian tube drainage, potentially leading to conductive hearing loss and cholesteatoma formation. Surgical drainage with myringotomy tubes is indicated when conservative medical management fails. Many children with congenital anomalies, such as those with cleft palate, Down’s syndrome, and craniofacial abnormalities, require myringotomy tubes secondary to abnormal eustachian tube anatomy. General anesthesia is required for this brief ambulatory procedure and is often accomplished with an inhalational anesthetic, usually sevoflurane, oxygen and/or nitrous oxide by a facemask. An oropharyngeal airway may help maintain airway patency while sharing the airway with the otolaryngologist and minimize head movements as perceived by the otolaryngologist through the microscope. Additionally, this procedure may also be surgically challenging and longer in children with narrow ear canals, such as children with Down’s syndrome and craniofacial abnormalities, and a supraglottic airway (SGA) or an endotracheal tube (ETT) should be considered for maintenance of anesthesia. Intravenous access is usually not needed unless significant airway obstruction or hemodynamic instability is expected; for example, children with Down’s syndrome may develop significant bradyarrythmias with sevoflurane inhalational induction, and children with hypotonia may develop airway obstruction following inhalational induction.
Introduction The normal carotid body is a small cluster of chemoreceptors located on the posterior aspect of the bifurcation of the common carotid artery (Figures 19.1 and 19.2) monitors changes in arterial oxygen tension and pH of the blood and, in turn, influences the rate and depth of respiration, and to a lesser extent heart rate. It was first anatomically described in 1743 by Albrecht von Haller [1]. The carotid body receives its blood supply from the common or external carotid artery and its innervation primarily from sensory (afferent) fibers of the glossopharyngeal (IX) nerve, with lesser contributions from the vagus (X) nerve and superior cervical ganglion of the sympathetic nervous system. Carotid body tumors (CBTs), also called paragangliomas, are highly vascular tumors (Figure 19.1) arising from these chemoreceptors cells, which develop from the neural crest region during embryogenesis. While carotid body tumors are rare, diagnosed with an incidence of about 1:30 000 in the general population, they account for 60% of head and neck paragangliomas [2].
Introduction An understanding of anatomy is paramount to the ability to safely anesthetize the head and neck surgery patient. In contrast to other patient populations, the head and neck surgery patient’s pathology may obfuscate normal anatomy and impede or even prevent the anesthesiologist from being able to intubate the patient. Furthermore, recognized anatomic variations may complicate the anesthesiologist’s management of the patient. Cooperation among the entire operating team is the key to a successful operation. The surgeon and anesthesiologist must discuss the particular patient’s anatomy and specific procedural needs prior to each case. Potential airway management options such as routine oral intubation, nasotracheal intubation, awake fiberoptic intubation and even awake tracheotomy must be considered. Contemporary technological advances can enhance this discussion by including photography and videography. For example, computerized imaging systems in use in modern operating rooms can be synchronized to a server in the otolaryngology clinic to allow the review of both photographs and videos of patients’ airways and the extent that they have been altered through disease progression. While the added dimension of visual review integrated into the discussion can be an invaluable adjunct to this team approach, always bear in mind that conditions could have worsened significantly since the imaging was performed. Patient safety concerns continue to be increasingly recognized as a vital component of modern health care. At the authors’ institution we perform both an operative "huddle" with the patient awake and a surgical "time-out" prior to performing any procedure. The huddle is an ideal time to review the intubation plan including the use or avoidance of long-acting muscle relaxants for the case. The huddle process also ensures that both the anesthesiologist and surgeon are present and ready to handle any potential perioperative complications. The head and neck surgeon should be considered an airway specialist and partner with the anesthesiologist.
Introduction Lasers are commonly used in otolaryngologic surgery (Table 25.1), in plastic surgery (for instance, in the removal of port wine birthmarks), in gynecologic surgery (for instance, in the treatment of endometriosis), in ophthalmic surgery (for instance, in retinal surgery) and elsewhere [1,2]. Depending on the clinical circumstances, various laser types producing light (photons) of different wavelength (color) are employed (Table 25.2). The most widely utilized laser in ENT surgery is the carbon dioxide (CO2) laser. It allows precise cutting with a particularly fine zone of coagulation that helps reduce surgical bleeding. It can be especially useful in the removal of obstructing laryngeal carcinomas, the removal of lingual tonsillar tissue, the ablation of hemangiomas, and the resection of small oropharyngeal malignant lesions. The carbon dioxide laser can be used either as a precision cutting instrument or as a tissue vaporizer depending on the extent to which the beam is focused. Tissue vaporization is particularly efficient with the carbon dioxide laser because of the excellent absorption of the produced far infrared photons (10 600 nm wavelength) by water present in tissue.
Diagnostic bronchoscopic procedures are performed every day by both pulmonologists and thoracic surgeons. Diagnostic bronchoscopy is indicated for airway exam, bronchioalveolar lavage, biopsy of airway lesions, autofluorescence bronchoscopy, and narrow band imaging. Most of the diagnostic procedures are performed in an outpatient setting under moderate (conscious) sedation in conjunction with local anesthesia to numb the airway. Moderate sedation is commonly provided by a trained sedation nurse under the supervision of the bronchoscopist and has become a well-accepted method of providing anesthesia for diagnostic bronchoscopy. The short duration of diagnostic bronchoscopy procedures makes moderate sedation a suitable method of anesthesia [1]. In recent years more prolonged sophisticated diagnostic bronchoscopic procedures have emerged. These include endobronchial ultrasound with fine-needle aspiration (EBUS-FNA) [2], staging of lung cancer, and electromagnetic navigation (EMN) with biopsy of peripheral lung lesions. These procedures require a longer duration and a quiet field for precise targeting of the mediastinal lymph nodes or lung lesions without injury to surrounding large vessels or breach of the pleura. As a result there is increasing demand for general anesthesia under the care of anesthesiologists for advanced diagnostic bronchoscopic procedures. The demand for the advanced diagnostic bronchoscopic procedures is increasing as these procedures provide a minimally invasive approach. Although it seems intuitive to perform general anesthesia for airway procedures in the operating room, the current practice is that most of these procedures are performed in interventional bronchoscopy suites that have been modified to mimic an operating room (Figure 30.1) These suites are commonly found in large academic centers with high volumes of patients needing advanced diagnostic bronchoscopic procedures on a daily basis. Several factors have caused the shift of performing such airway procedures to outside the operating room. These include the high safety profile of EBUS-FNA, the increased cost of performing procedures in the operating room, inability to obtain operating room block time on short notice for the pulmonologists, and the cumbersome process of moving the equipment required to perform the procedures to the operating room. The interventional bronchoscopy suites are designed with both safety and excellence in mind [3]. The American Society of Anesthesiology guidelines on establishing out of the operating room anesthesia support have to be implemented during the design of such interventional bronchoscopic suites [4].
Introduction Head trauma accounts for 10 to 15% (approximately 230000) of trauma hospitalizations in the United States per year, resulting in the second leading cause of trauma hospitalizations [1]. Further, trauma is the leading cause of death and disability in Americans younger than 40 years of age [2]. Although motor vehicle accidents and falls account for the majority of head trauma in the United States, such injuries often occur with sporting accidents or assaults. Maxillofacial trauma poses a difficult challenge for the anesthesiologist with regard to the patient’s airway. Injuries to the head and neck may result in airway obstruction from disrupted or distorted anatomy, tissue edema, foreign debris, vomitus, or bleeding. Craniofacial injuries may distort the anatomy of the tongue or pharynx to such an extent that airway patency is compromised. Traumatic brain injury may result in loss of central mechanisms of airway protection. Trauma to the neck may additionally cause direct airway obstruction when there is injury to the larynx. While airway management will be discussed in this chapter, the overriding principle in the event of an inability to quickly establish an airway should be to perform a surgical airway. In a report of patients with laryngeal fractures, 74% required advanced airway techniques [3].
Introduction Most patients undergoing thyroid surgery have thyroid cancer, a symptomatic thyroid goiter, or a contraindication to or failure of medical management of their hyperthyroidism. The National Cancer Institute estimates that 37 000 women and 11 000 men were diagnosed with primary thyroid cancer in the USA in 2011. It is the fifth most common cancer among women yet accounts for less than 2% of cancer deaths. Papillary and follicular thyroid cancers account for approximately 80% and 15% of cases respectively and are generally cured by early recognition and surgical excision. Medullary thyroid cancer may produce calcitonin or be associated with other endocrine adenopathies or familial medullary cancer. The least common form of primary thyroid cancer is anaplastic and is associated with a very unfavourable prognosis with or without surgery (http://www.cancer.gov/cancertopicswyntk/thyroid; accessed Oct. 28, 2011). Preoperative assessment for thyroid surgery There are several specific issues that significantly affect the anesthetic management for patients undergoing thyroid surgery. In addition to the general considerations pertaining to anesthesia, specific attention should be directed to the assessment of thyroid function, the size and location of the thyroid gland, its relationship to the trachea and adjacent vascular structures, and the co-existence of a multiple endocrine neoplasia (MEN1 or 2).
Introduction This chapter is intended as a minimal synopsis of selected airway pathology in terms of associated anesthetic and airway implications. The case types covered in the following discussion are those where awake intubation by some means (e.g., by fiberoptic methods) is often the method of choice. Where awake intubation is impractical (e.g., inadequate equipment or experience) tracheostomy under local anesthesia (with minimal or no sedation in extreme cases) is often advocated as the best means of managing the airway. In all the conditions discussed herein, complete airway obstruction is the outcome that is most feared, and this can easily occur when sedating agents such as propofol are used, as they lower the tone of the airway musculature, thereby changing the airway architecture. Our selection of pathologic conditions herein is a rather limited sampling of only the most commonly encountered pathologic conditions in clinical practice; for more unusual pathologic entities that impact on the airway, more information is available from other chapters of this book and recourse to the abundant ENT literature is encouraged.
Introduction The anesthesiologist and otolaryngologist share the airway. The surgeon requires adequate visualization of the pathology to perform surgery and the anesthesiologist requires adequate oxygenation and ventilation. While communication between the anesthesiologist and the otolaryngologist is crucial, it is also prudent for the anesthesiologist to become familiar with the equipment used by the otolaryngologist, particularly when the surgical procedure involves the upper aerodigestive tract. This chapter will introduce and discuss some of the more common equipment used during procedures involving the larynx, trachea, cervical esophagus, pharynx, and paranasal sinuses. Surgery of the larynx and trachea Surgery of the larynx, pharynx, and trachea begins with securing the airway with an appropriate device that will allow for adequate ventilation. Often, a smaller-sized endotracheal tube or an endotracheal tube that is safe for laser surgery is selected (Figure 2.1). There are also occasions where the patient’s pathology may preclude the use of an endotracheal tube and require the use of jet ventilation. Jet ventilation is typically employed via a subglottic Hunsaker catheter, via supraglottic attachment to the laryngoscope (Figure 2.2), or via jet laryngoscope. Both techniques have been found to be useful and safe for microlaryngeal surgery [1-3]. For certain tracheal pathology, the use of a rigid bronchoscope (Figure 2.3) may be necessary. In this situation, the anesthesiologist can connect the breathing circuit to the rigid bronchoscope’s side port. For airway obstructive pathology, the surgeon may also employ dilatational balloons and powered instrumentation, such as a micro-debrider, to increase the airway diameter (Figure 2.4).
Introduction Procedure overview Panendoscopy or "triple endoscopy" encompasses rigid laryngoscopy, bronchoscopy, and esophagoscopy. It is primarily used to evaluate the patient with head and neck cancer, in order to document the extent of a tumor, obtain a biopsy for tissue diagnosis, search for a synchronous primary tumor or to look for recurrence post treatment. Other indications include vocal cord lesions and pathology involving the pharynx, larynx or tongue. Following induction of general anesthesia, the patient is placed in the "Jackson position" to maximize laryngeal exposure, with the neck flexed and the head extended. A shoulder roll assists with obtaining this position and a head ring stabilizes the head. If the neck cannot be extended due to arthritis or a fixed flexion deformity, or there is a contraindication to neck extension such as an unstable cervical spine or myelopathy, correct placement of the laryngoscope is hindered [1]. In these patients a flexible bronchoscope should be considered. The eyes are covered and the upper dentition is protected with a mouth guard or folded gauze. The laryngoscope is inserted and the surgeon completes an examination of the pharynx and supraglottic larynx. The vocal cords are exposed and examined. Next, the laryngoscope is exchanged for a rigid bronchoscope, which is guided past the base of the tongue under the epiglottis and through the vocal cords into the trachea. Esophagoscopy usually proceeds next.
Introduction/background Cancers of the aerodigestive system are rare. Each year they account for 2.5% of the new cases of cancer in North America [1]. Of these, there are approximately 3560 new cases of laryngeal cancer. Squamous cell carcinoma is the most common type. The major risk factors for the development of laryngeal cancers are tobacco and alcohol use, acting synergistically to increase the risk of cancer [2]. The 5 year survival rate for laryngeal squamous cell carcinoma is 64% [3]. Mortality has remained largely unchanged over the past 20 years [1], with some authorities reporting a decline in survival [3], occurring despite improvement in surgical techniques, supplemented by perioperative chemotherapy and radiotherapy. Recent research has focused on molecular biology to provide new treatment options and target therapy. The terms neck dissection and laryngectomy describe a wide variety of surgical procedures that attempt to remove a cancer and its main route of spread. The extent of a given procedure is dictated by the extent of the cancer. Neck dissection is commonly performed in the treatment of different cancers of the head and neck to remove metastatic tumor deposits and the route of spread. Balancing anesthesia for the surgical requirements of these procedures can be a significant challenge.
Introduction The paired parotid glands are the largest among the three major salivary glands in the human body (the other two are the submandibular and subglottic glands). They are located on the side of the cheeks, anterior and inferior to the external ear, resembling an inverted pyramid in shape, with their base extending from the zygomatic arch and their apex overlying and wrapping around the mandibular angle. Because of their superficial localization, they can be palpated. The saliva secretion drains through the Stensen’s duct into the parotid papilla, which is located on the buccal mucosa opposite the upper second molar. The parotid gland is encapsulated between the superficial and deep layers of the parotid gland fascia (PGF). The superficial PGF is thick and covers the parotid gland, extends over the masseter muscle and attaches to the zygomatic arch. There is a lax space between the superficial PGF and the gland, which allows for easy separation. The deep layer of the PGF is thin and underlies the deep lobe of the parotid gland [1]. The facial nerve (extratemporal segment) crosses lateral to the styloid process and approaches the parotid gland posteriorly. It penetrates the parotid gland, and runs in the body of the gland separating the deep and superficial lobes.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Introduction Patients presenting to the operating room must be evaluated for the presence of anatomic or functional issues which may affect safe airway control, regardless of the need to employ general anesthesia. If monitored anesthesia care with sedation or infiltrative or regional anesthesia is anticipated, an airway plan is still needed [1]. All patients fall into one of three broad categories: the patient with no known or suspected airway abnormalities, the patient with obvious airway distortion, and the patient with "unknown" airway disease, i.e., presenting with a diagnosis of pathology affecting some part of the airway. Using the American Society of Anesthesiologist (ASA) difficult airway algorithm as a benchmark, the first group of patients is managed via the routine induction root point (Figure 5.1, box B) that includes the control of the airway after the induction of anesthesia [2]. On occasion, problems with noninvasive ventilation or tracheal intubation (by one or any means) may occur. The ASA algorithm provides for these occurrences with guidelines for the use of alternative ventilation/intubation techniques, returning to spontaneous ventilation and, eventually, invasive airways. The large majority of patients presenting to the operating room will enter the ASA algorithm at this root point.
Anesthesia for Otolaryngologic Surgery offers a comprehensive synopsis of the anesthetic management options for otolaryngologic and bronchoscopic procedures. Authored by world authorities in the fields of anesthesiology and otolaryngology, both theoretical concepts and practical issues are addressed in detail, providing literature-based evidence wherever available and offering expert clinical opinion where rigorous scientific evidence is lacking. A full chapter is dedicated to every common surgical ENT procedure, as well as less common procedures such as face transplantation. Clinical chapters are enriched with case descriptions, making the text applicable to everyday practice. Chapters are also enhanced by numerous illustrations and recommended anesthetic management plans, as well as hints and tips that draw on the authors' extensive experience. Comprehensively reviewing the whole field, Anesthesia for Otolaryngologic Surgery is an invaluable resource for every clinician involved in the care of ENT surgical patients, including anesthesiologists, otolaryngologists and pulmonologists.
Use of the laryngeal mask airway (LMA) permits the maintenance of a patent airway with successful insertion rates of the LMA on the first attempt varying between 67%-92% in children. The recommended insertion technique involves deflation of the mask using a syringe, and application of a lubricant jelly. In a randomized study of 122 children, we compared the time to complete LMA insertion, the number of attempts before successful placement, and the occurrence of laryngospasm and Spo2 < 90% during insertion using the standard deflated method and an alternative method of insertion with the LMA cuff partially inflated. Independently, the children were randomly assigned to have K-Y sterile lubricating jelly or 2% lidocaine topical solution applied to the back of the mask. The occurrence of coughing, laryngospasm, and vomiting during emergence were recorded. Insertion of the LMA partially inflated required significantly less time (16 vs 23 s, P < 0.05), and was associated with a higher success rate on first attempts (85.5% vs 96.7%, P < 0.05). In those who did not receive morphine, 2% lidocaine topical solution decreased the incidence of coughing on emergence (10.3% vs 36.4%). The ease of insertion of the LMA in children was improved by partial inflation of the cuff and in addition, 2% lidocaine topical solution was as beneficial as morphine in reducing coughing on emergence.
The LMA is a useful airway device for most adult and pediatric patients. It is easy and atraumatic to insert, with minimal somatic and autonomic responses from the patient. It is a suitable alternative to the face mask and to tracheal intubation in a wide variety of clinical situations. In addition, the LMA facilitates blind and fiberoptic techniques of intubation, but its role in the emergency scenario has yet to be established. The preliminary experience gained with this device in Europe and Australasia suggests that it may also transform contemporary anesthetic practice in the United States.
Unlabelled:
The purpose of the study was to compare the ease of insertion of the laryngeal mask airway using the standard uninflated approach or with a fully inflated cuff. Two hundred consecutive patients undergoing anesthesia using a laryngeal mask airway were randomized to have the laryngeal mask inserted using either method. Successful insertion was judged primarily by the clinical function of the airway. The number of insertion attempts to achieve a satisfactory airway and whether an alternative technique was required for success were recorded. On removal of the laryngeal mask, a blind observer noted the presence or absence of blood. Just before leaving the recovery room, each patient was asked whether they had a sore throat. Insertion technique made no difference with regard to first attempt success. However, the presence of blood on the removed masks (P < 0.01) and sore throat (P < 0.01) were less frequent in the inflated cuff group. We conclude that the inflated cuff insertion technique is an acceptable alternative to the standard approach and has the advantage of reducing the incidence of minor pharyngeal mucosal trauma, as evidenced by mucosal bleeding and sore throat.
Implications:
Insertion of the laryngeal mask airway with the cuff fully inflated is equally successful to the standard uninflated approach in experienced hands. The inflated technique was associated with less minor pharyngeal mucosal trauma and, consequently, a lower incidence of postoperative sore throat. This implies that the inflated technique would be acceptable to the general population of laryngeal mask users.
The laryngeal mask airway: its uses in anesthesiology , [5] Benumof J. Laryngeal mask airway and the ASA difficult airway algorithm
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Pennant J, White P. The laryngeal mask airway: its uses in anesthesiology. Anesthesiology 1993;79:144-63., [5] Benumof J. Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 1996;84:686-99.
Pediatric airway A practice of anesthesia for infants and children
- M Wheeler
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- Todres Id Cote
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Wheeler M, Coté CJ, Todres ID. Pediatric airway. In: Cote CJ, Ryan JF, Todres ID, et al, editors. A practice of anesthesia for infants and children. 3 rd edition. Philadelphia: WB Saunders; 2001. p. 85.
The laryngeal mask airway: a comparison between two insertion techniques
- Wakeling