Andrew Paul Feinberg, M.D., M.P.H.

• Bloomberg Distinguished Professor, Johns Hopkins University School of Medicine, Whiting School of Engineering, and Bloomberg School of Public Health
• Professor of Medicine

https://www.hopkinsmedicine.org/profiles/results/directory/profile/5351655/andrew-feinberg-1

It also describes recent advances and scanning technology that can shed light on changes in functional anatomy of the lower airway in disease states such the extent to which the retractive forces affect airway morphology is related to the specific structure of the airway segment in question symptoms bipolar cheap generic zofran uk. Notice that the mucous membrane is thrown into folds in the contracted and collapsed states medications bad for your liver purchase zofran 8 mg, reducing the airway lumen medications list form cheap generic zofran uk. Practitioners involved in airway management should possess knowledge of the structures that they will frequently use as a passageway to care of patients in their professional career medicine 91360 discount zofran 4mg fast delivery. Physiological and pathophysiological implications of upper airway reflexes in humans treatment emergent adverse event 4mg zofran with mastercard. Paranasal sinusitis associated with nasotracheal intubation: a frequently unrecognized and treatable source of sepsis medications not to crush zofran 4 mg with amex. The effect of gender on compensatory neuromuscular response to upper airway obstruction in normal subjects under midazolam general anesthesia. Assessment of upper airway anatomy in awake, sedated and anaesthetised patients using magnetic resonance imaging. Magnetic resonance imaging of the upper airway: effects of propofol anesthesia and nasal continuous positive airway pressure in humans. Computerized tomography in obstructive sleep apnea: correlation of airway size with physiology during sleep and wakefulness. Determining the site of airway obstruction in obstructive sleep apnea with airway pressure measurements during sleep. The effectiveness of cricoid pressure for occluding the esophageal entrance in anesthetized and paralyzed patients: an experimental and observational glidescope study. The dimensions and vascular anatomy of the cricothyroid membrane: relevance to emergent surgical airway access. Cricoarytenoid arthritis: a cause of acute upper airway obstruction in rheumatoid arthritis. Severe upper airway obstruction from cricoarytenoiditis as the sole presenting manifestation of a systemic lupus erythematosus flare. Episodic paroxysmal laryngospasm: voice and pulmonary function assessment and management. Postoperative vocal cord paralysis in paediatric patients: reports of cases and a review of possible aetiological factors. Anatomy, pathology, and physiology of the tracheobronchial tree: emphasis on the distal airways. Lengthening of the trachea during neck extension: which part of the trachea is stretched Elongation of the trachea during neck extension in children: implications of the safety of endotracheal tubes. Movement of the distal end of the endotracheal tube during flexion and extension of the neck. The wonderful world of the windpipe: a review of central airway anatomy and pathology. Correlation between the bronchial subepithelial layer and whole airway wall thickness in patients with asthma. This bonus information about the airway can be aptly used for formulating an anesthetic plan. The main goal of this chapter is to introduce airway practitioners to normal airway anatomy, as visualized on radiography (plain film or digital radiograph) and cross-sectional imaging. The technology behind the different imaging modalities, as well as their technical differences, is briefly reviewed, with the main emphasis placed on evaluation of the airway using available radiologic studies, which most patients already have as part of their often-extensive medical workup. Familiarity with the normal anatomy and its variants is often more useful than an exhaustive list of esoteric diagnoses. Therefore our clinical examples focus on the pathologic processes involving the airway that are most relevant to anesthesiologists and include a short discussion of some common abnormalities. The macroscopic airway can be regarded as a tubular conduit for air inhaled from the nares to the tracheobronchial tree. The integrity of the airway with its natural contrast is usually referenced with respect to extrinsic compression, luminal encroachment, or airway displacement. Segmentation of the airway into the head, neck, and chest compartments is artificial but usually done, conforming to the different medical disciplines addressing the pathologies affecting these anatomic regions and for ease of discussion. This is especially important when selecting a study that will best depict the anatomic structures and pathologic processes of the airway that are of clinical interest. Computed Tomography After the discovery of x-rays, it became apparent that images of the internal structures of the human body could yield important diagnostic information. However, the usefulness of the x-rays is limited by the projection of a three-dimensional object onto a two-dimensional display. With x-rays and radiographs, the details of internal objects are masked by the shadows of overlying and underlying structures. Thus the goal of diagnostic imaging is to bring forth the organ or area of interest in detail and eliminate the unwanted information. The patient is enclosed in a gantry, and a fan-shaped x-ray source rotates around him or her. The radiation counted by the detectors is analyzed using mathematical equations to localize and characterize the tissues within the imaged section based on density and attenuation measurements. The gantry must then "unwind" to prepare for the next slice while the table with the patient moves forward or backward a distance predetermined by slice thickness. An intrinsic limitation of this technique is the time necessary for movement of the mechanical parts. Volumetric information also makes it possible to identify small lesions more accurately and allows better three-dimensional reconstruction. This is especially important when scanning uncooperative patients and trauma victims. Imaging Modalities A brief description of the different imaging modalities is presented here, starting with plain x-ray films and more currently, digital radiographs. This will enable the reader to develop a good foundation for understanding how different imaging modalities are used in modern diagnostic imaging. Conventional Radiograph (Plain Film, X-Ray) and Digital Radiograph Wilhelm Conrad Roentgen, a German physicist, discovered x-rays on November 8, 1895, while studying the behavior of cathode rays (electrons) in high-energy cathode ray tubes. By serendipity, he noted that a mysterious ray that escaped the cathode ray tube struck a small piece of paper coated with fluorescent barium platinocyanide on a workbench 3 feet away, causing a faint fluorescent glow. Different objects placed between the cathode ray tube and the fluorescent screen changed the brightness of the fluorescence, indicating that the mysterious ray penetrated objects differently. When Roentgen held his hand between the tube and the screen and saw the outline of the bony skeleton of his hand, he quickly realized the significance of his discovery. Other types of electromagnetic radiation include radio waves, radiant heat, and visible light. In diagnostic radiology, the predominant energy source used for imaging is ionizing radiation, such as alpha particles, beta particles, gamma rays, and x-rays. The science of electromagnetic waves and x-ray generation is very complex and exceeds the scope of this chapter. In principle, x-rays are produced by energy conversion as a fast stream of electrons is suddenly decelerated in an x-ray tube. The final image is dependent on the degree of attenuation of the beam by matter. Attenuation, the reduction in the intensity of the beam as it traverses matter of different constituents, is caused by the absorption or deflection of photons from the beam. The transmitted beam determines the final image, which is represented in shades of gray. An example would be bone, a high-density material that attenuates much of the x-ray beam; images of bone on radiographs are very bright or white. The conventional plain film, or x-ray, is obtained using screen film cassette technology in which the film is processed using several chemical "washes" or chemical reactions to produce a two-dimensional image of the body part under examination on a large field of view film. Instead, imaging is based on the resonance of the atomic nuclei of certain elements such as sodium, phosphorus, and hydrogen in response to radio waves of the same frequency produced in a static magnetic field environment. Every water molecule contains two hydrogen atoms, and larger molecules, such as lipids and proteins, contain many hydrogen atoms. When radio waves are applied, protons are knocked out of natural alignment, and when the radio wave is stopped, the protons return to their original state of equilibrium, realigning to the steady magnetic field and emitting energy, which is translated into weak radio signals. The time it takes for the protons to realign is referred to as a relaxation time and is dependent on the tissue composition and cellular environment. The relaxation times, T1 and T2, for each tissue type are expressed as constants at a given magnetic field strength. Imaging that optimizes T1 or T2 characteristics is referred to as T1-weighted or T2-weighted imaging. Tissue response to pathologic processes usually includes an increase in bound water, or edema, which lengthens the T2 relaxation time and appears as a bright focus on T2-weighted images. One must also remove pagers, telephones, computers, credit cards, and analog watches because the strong magnetic field can cause malfunction or permanent damage. Patients must be carefully screened for implantable pacemakers, intracranial aneurysm clips, implants. In addition to the risk of ferromagnetic objects acting as a projectile externally, producing unwanted movement internally, or causing equipment malfunction, there is also the risk of heating, which can cause severe thermal injuries to the patient. Basics of Radiograph Interpretation the aim of this chapter is to review imaging of the airway. There is, however, useful information from imaging studies of other parts of the body. For example, imaging of the brain can give information regarding intracranial pathology such as masses and mass effect, including brain herniation, hemorrhage, and hydrocephalus. Abdominal imaging provides information regarding the presence or absence of ileus, pneumoperitoneum, and mass effect. To illustrate the usefulness of radiography in evaluating the airway, we focus our discussion on the interpretation of plain films or digital radiographs of the cervical spine, chest, and neck. They are also the most relevant to anesthesiologists because a composite of these studies gives a picture of the entire airway. Although these radiologic studies are usually obtained for reasons other than airway evaluation, it is in this group of patients who are "normal" or "cleared for surgery" that one may glean important observations about the airway. With a dedicated study of the neck or cervical spine, multidimensional reconstructions from those studies allow an excellent view of the airway, usually from the nares to tracheal bifurcation. The following sections address the basics of imaging interpretation with respect to the airway anatomy and pathology. Cervical Spine Radiography Radiologic Anatomy the cervical spine articulates with the occiput cranially and the thoracic vertebrae caudally. The bony elements, muscles, ligaments, and intervertebral discs support and provide protection to the spinal cord. On a lateral radiograph of the cervical spine, one can appreciate the bony morphology of the vertebrae and the disc spaces and assess the alignment of the vertebral column very quickly. This indirectly provides information regarding the integrity of the ligaments, which are crucial in maintaining alignment of the cervical spine. Individual ligaments and muscle groups, however, all have the same or similar attenuation and cannot be differentiated from one another on a radiograph. Regardless of the type of imaging study, a systematic approach is recommended to evaluate the spine for bony integrity, alignment, cartilage, joint space, and soft tissue abnormalities. C1 and C2 are different from the other cervical vertebrae and are more considered a part of the cervicocranium. The atlas (C1) is a ring-like vertebra characterized by the absence of a vertebral body. It does not contain pedicles or laminae, as do other vertebrae, and has no true spinous process. The anterior and posterior arches are relatively thin, and the lateral masses are heavy and thick structures. Rudimentary transverse processes extend laterally and contain the transverse foramina, through which pass the vertebral arteries. Fusion of the anterior arch is complete between the seventh and tenth years of life. During the second year of life, the center of the posterior tubercle appears, and by the end of the fourth year of life, the posterior arch becomes complete. The odontoid process (dens) serves as the theoretical body of C1, around which the atlas rotates and bends laterally. The dens is situated between the lateral masses of the atlas and is maintained in its normal sagittal relationship to the anterior arch of C1 by several ligaments, most important of which is the transverse atlantal ligament. Superiorly, the dentate (apical) ligament extends from the tip of the clivus to the tip of the dens. Alar ligaments secure the tip of the dens to the occipital condyles and to the lateral masses of the atlas. The tectorial membrane is a continuum of the posterior longitudinal ligament from the body of C2 to the upper surface of the occipital bone, anterior to the foramen magnum. The C2 vertebra arises from five or six separate ossification centers, depending upon whether the vertebral body has one or two centers. The vertebral body is ossified at birth, and the posterior arch is partially ossified. They fuse posteriorly by the second or third year of life and unite with the body of the vertebrae by the seventh year. The dens ossifies from two vertically oriented centers that fuse by the seventh fetal month. Failure of the ossiculum terminale to either develop or unite with the dens may result in a bulbous cleft dens tip. Axial computed tomography, bone dental ossification center is called the os terminale and may be mistaken for a fracture of the odontoid tip. From C3 to C7, the cervical vertebrae are uniform in shape but increase in size, with the seventh vertebra being the largest and heaviest. All the vertebrae have transverse processes containing the foramen transversarium through which the vertebral arteries pass.

Swallowing disorders in patients with prolonged orotracheal intubation or tracheostomy tubes medicine nobel prize 2015 discount zofran 4 mg mastercard. Swallowing dysfunction in nonneurologic critically ill patients who require percutaneous dilatational tracheostomy symptoms after embryo transfer buy zofran without a prescription. Cricothyrotomy performed by prehospital personnel: a comparison of two techniques in a human cadaver model symptoms bladder infection buy 4mg zofran free shipping. A comprehensive treatment atrial fibrillation order cheapest zofran, unembalmed cadaver-based course in advanced emergency procedures for medical students symptoms stomach ulcer buy generic zofran from india. The educational impact of bench model fidelity on the acquisition of technical skill: the use of clinically relevant outcome measures my medicine generic zofran 4mg without prescription. Although the advent of flexible bronchoscopy has given physicians improved access to more distal portions of the tracheobronchial tree with a more rapid learning curve and less patient discomfort compared with rigid bronchoscopy,2 there are still several situations in which rigid bronchoscopy is more appropriate. The larger working port and defined structure of the instrument make rigid bronchoscopy useful for surgical interventions within the airway, such as the removal of foreign bodies and masses. In practice, most of the factors limiting rigid bronchoscopy are related to the need for general anesthesia, such as an unstable cardiovascular or respiratory status. In this instance, flexible bronchoscopy is indicated to avoid further spinal injury. Other contraindications include laryngeal stenosis that prevents passage of the bronchoscope, limited range of motion of the mandible, severe kyphoscoliosis, uncontrolled coagulopathy, and extreme ventilatory/oxygenation demands. The development of local anesthesia in 1880 also made bronchoscopy more tolerable. In March 1897, Gustave Killian passed an endoscope through the larynx and removed a piece of pork bone from the right mainstem bronchus using cocaine anesthesia. Hopkins of England invented the first conventional lens system by using glass rods instead of small lenses, which produced a significantly brighter image, occupied less space, and allowed for greater visualization of an object in a single field. The anesthesia circuit attaches inferiorly, the prismatic light source superiorly, and the suction port at an angle. The bronchoscope is a hollow, rigid metal tube that is tapered and beveled on the distal end and has a series of ports on the proximal end that serve different purposes. There are side holes at the distal portion of the bronchoscope to allow for ventilation just proximal to the tip. The central, in-line port is the working channel used for insertion of instruments such as telescopes, biopsy forceps, laser fibers, balloon devices, cryotherapy probes, and stents. The port can be left open to allow room air into the system, or it can be closed to prevent leakage of air or anesthetic gases, depending on the ventilation strategy and anesthetic technique being used. Telescopes with different angles (0, 30, and 70 degrees), lengths, and diameters can be inserted through the main working port to visualize areas that are difficult to see with the rigid bronchoscope alone-namely, the right and left upper bronchial orifices and the right middle bronchial orifice. This last configuration has the advantage of providing both proximal and distal illumination. A full set of ventilating bronchoscopes and a backup light source should be available. The monitor is shared so that it may be viewed simultaneously by the bronchoscopist and the anesthesiologist. In patients with suspected bleeding disorders, functional coagulation studies, such as thromboelastography, may be useful. Because patients with uremia have qualitative platelet abnormalities that can predispose to excessive bleeding, creatinine and blood urea nitrogen values should be considered as well. Additional laboratory studies and tests may be ordered depending on the patient history. A 12-lead electrocardiogram is required for patients with cardiac risk factors such as smoking, diabetes mellitus, arterial hypertension, or hypercholesterolemia and for those with a significant cardiac history. Pulmonary function testing is no longer indicated as routine preoperative assessment of respiratory disease but may be useful for determining a postoperative plan. Optional items include a flexible bronchoscope that can be passed through the rigid bronchoscope for further examination of the lower tracheobronchial tree. Anesthesia for Bronchoscopy Because of the nature of the procedure and sharing of the airway, the anesthesiologist and surgeon must be in constant communication during a rigid bronchoscopy procedure. The goals for anesthesia during bronchoscopy include provision of amnesia and analgesia, muscle relaxation as needed to accomplish the exposure, blunting of respiratory tract reactivity and reflexes, maintenance of adequate oxygenation, and achieving prompt emergence at the conclusion of the procedure. General anesthesia is typically used to prevent unnecessary patient movement and possible unintentional damage to the airway. As previously described, rigid bronchoscopes have ventilating ports that can be attached to the anesthesia circuit directly, allowing anesthetic gases and oxygen to flow continuously during the procedure. Disadvantages of inhalational anesthesia with spontaneous respiration include difficulty in maintaining an adequate plane of anesthetic depth and anesthetic pollution of the surgical environment from a gas leak around the bronchoscope. However, the depth of anesthesia required for the procedure itself may suppress both cardiac output and the respiratory drive, making spontaneous respirations inadequate. Positive pressure is administered by squeezing the reservoir bag or by using the mechanical ventilator, forcing gas pressure through the rigid bronchoscope. Finally, the size of the bronchoscope and the presence of a telescope in the lumen increases resistance to airflow and increases dead space ventilation, making ventilation more difficult. In apneic oxygenation, the surgeon and anesthesiologist coordinate periods of withheld ventilation during which the surgeon works. Under direct visualization, a catheter is then passed to the carina, and the flow rate of oxygen is set. High-pressure oxygen (50 psi) is delivered to the airway at high velocities, creating a negative pressure and causing a Venturi effect. Exhalation is passive and relies on the collapse of the airway once the pressure is removed. Sufficient time and an open pathway for air egress must be ensured during this technique to prevent stacked breaths and progressive hyperinflation. This method is contraindicated in foreign body removal, because the high-flow air may dislodge the foreign body and cause a complete obstruction. Opioids are often used for analgesia, sedation, and reduction of the cough reflex. However, because they depress the respiratory drive, they should be used with caution in patients who have signs of airway obstruction or a foreign body. The addition of opioid to a propofol-based anesthetic has been demonstrated to depress average oxygen saturation as measured by pulse oximetry (SpO2; 96. The intrinsic antitussive properties of propofol may obviate the need for opioids in many patients. Anticholinergics are often used to reduce airway secretions and have been shown to enhance the absorption and prolong the analgesic action of topical analgesics such as lidocaine, which are administered to the airways to reduce reactivity, prevent bronchospasm, and dampen the systemic reaction to airway manipulation. Topical lidocaine may again be administered to prevent laryngospasm and diminish coughing. Surgical Technique the surgeon should verify that the necessary instrumentation is available before induction of anesthesia is initiated. In all patients, bronchoscopes one and two sizes smaller than the preselected one should be available in case the airway encountered is smaller than anticipated. The patient should be positioned with the neck flexed on the body and the head extended at the neck. The goal is to align the oral, pharyngeal, and tracheal axes to facilitate insertion of the bronchoscope. In both children and adults, a slotted laryngoscope can be used in combination with a telescope to examine the larynx and the airway before the rigid bronchoscope is inserted. This facilitates evaluation of the larynx without the risk of blind, unintentional dislodgement of a high airway foreign body. The rigid bronchoscope is then introduced within or adjacent to the lumen of the laryngoscope down to the level of the true vocal cords. This provides the path of least resistance and minimizes the risk of glottic damage. Although the beveled tip of the rigid bronchoscope is conventionally directed anteriorly, some surgeons advocate placing the tip along the posterior wall of the trachea to prevent damage to the membranous trachea. After visualization of the epiglottis, the tip of the bronchoscope is used to displace the epiglottis and tongue anteriorly. If the patient has had the larynx surgically removed or closed, the rigid bronchoscope should be placed only through the laryngostoma. The nondominant hand then holds the bronchoscope while the dominant hand is used for instrumentation of the airway for the duration of the procedure. The subglottis and trachea are examined, and any masses or mucosal discolorations should be thoroughly investigated (see Video 28. Flexible suction catheters can also be inserted through a smaller side port to prevent loss of the closed anesthesia circuit. This effect can be mitigated by premedicating the patient with a steroid, such as dexamethasone. The distal airways may be evaluated by inserting different-angled telescopes to view the tracheobronchial tree. The 30- and 90-degree telescopes are especially useful to examine the segmental orifices of the upper lobes, in particular the right upper lobe, which is often in a difficult location to access. For diagnostic bronchoscopy, bronchial brushings, washings, and biopsies are performed, in that order. The surgeon should communicate with the anesthesiologist regarding any topical medications used during the procedure. After the procedure is completed, secretions should be thoroughly suctioned to prevent atelectasis. If cervical spine disease with a contracted neck is present, rigid bronchoscopy may not be safely performed; a limited range of cervical motion precludes safe advancement of the scope into the airway, resulting in complications ranging from dental injury to perforation of the posterior pharynx, membranous trachea, or distal airway. It may be controlled by use of the bronchoscope to apply pressure to the bleeding site, thorough suction, local application of epinephrine, or intravenous vasopressin. Their incidence can be reduced by maintaining an adequate depth of anesthesia and by the topical application of a local anesthetic, such as lidocaine. Other agents, including opioids and beta-blockers, can be used to blunt the hemodynamic response to airway stimulation. If the patient does not respond to medical management, endotracheal intubation may be necessary. If severe, potentially obstructive, laryngeal edema is identified intraoperatively, consideration should be given to leaving the patient intubated until the edema resolves. Failure to communicate may lead to inadequate control of the airway and can result in hypercarbia, hypoxemia, or death, especially in patients with impending complete airway obstruction. This may entail preparation for tracheostomy or ventilatory bypass in an absolute emergency. Foreign Body Removal the removal of aspirated foreign bodies remains one of the primary indications for rigid bronchoscopy, especially in children, in whom the use of flexible bronchoscopy is comparatively risky. In 2013, the total number of deaths caused by aspiration or ingestion of foreign objects, including food, totaled 4864. The initial stage is usually characterized by a choking episode followed by coughing, gagging, and even obstruction of the airway. Whereas atelectasis is more common in adults, air trapping is more common in children. The second stage is usually asymptomatic, because the initial symptoms frequently resolve because of a fatigued cough reflex. It is imperative that both inspiratory and expiratory views be obtained whenever possible to evaluate for unilateral air trapping. In check-valve obstruction, commonly seen acutely, the foreign body permits airflow into the lung segment but blocks the airflow out of the lung segment. This results in a mediastinal shift away from the obstruction on an expiratory film. Stop-valve obstruction is seen when a foreign body has been present for an extended period; it is characterized by no airflow into, and subsequent collapse of, the affected lung segment. The rarest type of obstruction, the ball-valve type, permits airflow out of the lung segment but not into it. This phenomenon results in atelectasis and a mediastinal shift toward the obstructed segment on an expiratory film. If an acute complete obstruction is suspected, rigid bronchoscopy must be performed promptly. More frequently, however, the patient presents in the second or third stage, when there is adequate time to plan a successful and safe bronchoscopy. If possible, the procedure should be scheduled when experienced personnel are available, the instruments have been appropriately selected, and the patient is fasted appropriately to prevent aspiration of gastric contents. Controversy remains regarding the anesthetic approach during bronchoscopy for foreign body aspiration. Manual jet ventilation was found to decrease the risk of intraoperative hypoxemia. The factors associated with postoperative hypoxemia were plant seed as the foreign object and prolonged emergence from anesthesia. Patients with these characteristics should be closely monitored after the procedure. However, the objects are usually larger and need to be removed with the bronchoscope as a unit. Once the object is within the forceps, it is dislodged from the airway and the bronchoscope is advanced to cover the foreign object, preventing its being stripped off the forceps during withdrawal. Vegetable foreign bodies should be grasped lightly or retrieved with strong suction to avoid fragmentation of the foreign body into the distal airways. If residual granulation tissue is present and is the source of bleeding or residual obstruction, it may be resected at the repeat bronchoscopy.

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The tip of the airway is beveled to aid in following the airway and minimizing mucosal trauma as it is advanced through the nasal cavities and the nasopharynx medications given im zofran 4 mg line. The bevel on the nasal trumpet should be oriented facing the turbinates (laterally) medications related to the blood buy zofran 8 mg with visa, so that the leading edge moves along the septum symptoms xanax addiction buy zofran 8mg overnight delivery, avoiding the turbinates medications made from plants purchase discount zofran line. A trumpet inserted on the left side can follow its natural curvature into the nose (curvature facing downward) medicine for diarrhea discount zofran 8mg fast delivery, whereas insertion on the right should begin with the trumpet curvature upside down (curvature initially facing upward) medicine mountain scout ranch order generic zofran from india. As the tube makes the bend (indicated by a relative loss of resistance to advancement), it should be rotated back to its original orientation. The contraindications (absolute or relative) include known nasal airway occlusion, nasal fractures, marked septal deviation, coagulopathy (risk of epistaxis), prior transsphenoidal hypophysectomy or Caldwell-Luc procedures, cerebrospinal fluid rhinorrhea, known or suspected basilar skull fractures, and adenoid hypertrophy. Bleeding from the nares usually is attributable to anterior plexus bleeding, and it is treated by applying pressure to the nares. The patient may be positioned on his or her side to minimize the aspiration of blood. An otolaryngology consultation may be necessary to further treat posterior plexus bleeding. The management of submucosal tunneling into the retropharyngeal space is to withdraw the airway and obtain otolaryngology consultation. The technique is implemented in two steps: first the seal (placing the mask on the face) and then the "airway maneuver" (pulling the mandible into the mask). The thumb and index finger are placed on the dome around the collar ("C"), with fingers 3, 4, and 5 spread along the mandible such that the fifth finger anchors the mandibular angle ("E"). With an uneven distribution of the pressure on the dome and an inability to generate side-to-side pressure to improve the seal over the cheeks by the "C" portion of a left-hand technique, the leak usually occurs on the right side of the mask. The hooks on the connector define a limited surface available for the grip, reinforcing the "E-C" technique and discouraging a grip on the whole dome. A head strap using the hooks may improve the seal but will also displace the mandible posteriorly, flex the head on the cervical spine, and limit the ability to generate a mandibular advancement. The traditional practice of observing the patient through a generously exposed transparent dome reinforces a limited, suboptimal grip that may promote the very complications the clinician wishes to monitor, such as emesis and cyanosis. The concept of the fifth finger generating a jaw thrust at the mandibular angle has been demystified and proven ineffective. This is a power grip that generates even distribution of pressure on the dome, allowing control of the whole mask and side-to-side pressure. In a mannequin study, the bilateral "E-V" was superior to the "E-C" technique and was recommended to the novice. Possible gastric insufflation of ventilation gases is indicated by epigastric sounds and abdominal distention. Fingers of each hand are free to wrap around the mandible to achieve and sustain airway maneuvers (while fingers 2 to 5 apply a jaw thrust or a triple airway maneuver). Desired outcomes are normal oxygen saturation and capnography with acceptable airway pressure and satisfactory tidal volume. Oxygen desaturation is a late sign of ventilation failure masked by the routine preoxygenation. Use of objective ventilation parameters in the context of an optimal first attempt allows early acceptance of failure before oxygen desaturation. When gastric insufflation has been studied using inspiratory pressure alone, it has been detected by auscultation starting at an inspiratory pressure of 20 cm H2O and by ultrasonography at 15 cm H2O. The likely reason for the observation of gastric insufflation in these studies is related to the inspiratory flow rates used during the measurement. There is an increased risk for pulmonary aspiration in patients with full stomach, hiatal hernia, pharyngeal diverticula, and esophageal motility disorders. Patients with two, three, or more concurrent risk factors are at markedly increased risk for impossible mask ventilation. Increased fat deposits in the pharynx (soft/ solid imbalance), neck (reduced bone mobility), and chest wall (reduced pulmonary compliance) are the hallmarks of obesity. A large mask can be used in edentulous patients so that the chin fits entirely within the mask with the seal on the caudal surface of the chin. In this configuration, the cheeks fit within the sides of the mask, and the sides seal along the lateral maxilla and mandible. Leaving dentures in place will stabilize the facial anatomy during induction (though with the associated risk of dislodgement with consequent airway obstruction by this foreign body). Other oral stabilization technique places the caudal end of the mask between the lower lip and the alveolar ridge while drawing the lip over the mask or places the caudal end above the lower lip while maintaining head extension. Female anesthesia providers are at increased risk for left-side carpal tunnel syndrome. Two-handed mask ventilation technique should be practiced in elective operating room cases to maintain proficiency of the operator and familiarity of ancillary staff. In specific clinical circumstances, first attempt for ventilation with a supraglottic airway is a valid approach. This model may lead to an extended apnea time as the operator proceeds diligently from simple to complex maneuvers, extending the overall time of apnea during airway management, leading to hypoxemia. Consequently, it is left to the individual operator to process the information with disappointing results. An optimal first attempt should leave minimal room for subsequent adjustments, that is, it should prove effective on the first attempt and not require multiple adjustments. The lower cervical spine flexion generated by the sniffing position is needed for maximal extension of the occipitoatlanto-axial complex. Further research in the use of ventilation devices that control inspiratory flow rates, peak ventilatory pressures, and minute ventilation as well as allow the use of two-handed mask ventilation techniques in these patient populations is warranted. Thus this traditional practice is intended to help the practitioner potentially avoid a cannot intubate/cannot oxygenate scenario with the option of "backing out" of the anesthetic and allowing spontaneous ventilation to return. The process of allowing an unventilated unparalyzed patient to wake up after induction may be unpractical and dangerous (such as in the emergency medicine, prehospital, and critical care arenas) as the patient can be exposed to hypoxia, laryngospasm, pulmonary aspiration, negative pressure pulmonary edema, and the need for lifesaving airway techniques in a suboptimal setting. The use of sugammadex will consistently reverse rocuroniumgenerated neuromuscular blockade but not the effects of induction agents, opioids, and anesthetic gases. As muscle tone recovers following rapid reversal of neuromuscular relaxants with the patient still anesthetized, effective basic airway management is needed to support the resuming spontaneous ventilation. Controlled ventilation by mask is relatively contraindicated in patients at increased risk for aspiration of gastric contents; however, this contraindication applies principally to elective anesthetic cases, as mask ventilation is often mandatory in critically ill patients who require advanced airway management because of respiratory failure. Its main advantages are that it is self-inflating and readily portable, but it lacks the "feel" (airway compliance and resistance) that the clinician has with a circle system, and it requires a compressed oxygen source to deliver oxygen concentrations above that of room air. Ventilator settings that are useful in clinical practice are those that limit inspiratory flow rates to less than 40 L/min, limit peak inspiratory pressures to 20 cm H2O, and achieve a regular and brisk ventilatory rate such that the minute ventilation (which is the product of respiratory rate and tidal volume) equals or exceeds 9 L/min. Control panel display of a Draeger Apollo Anesthesia Machine adjusted to perform automated face mask ventilation. Rate is set to 20 breaths per minute; inspiratory to expiratory ratio is set to 1:1 (equal inhalation with exhalation time to decrease the inspiratory flow rates in order to avoid gastric insufflation). Positive end-expiratory pressure is set to 4 cm H2O to positively affect alveolar recruitment and provide static airway pressure to further maintain airway patency. May be used in an "Automatic Mode," which will automatically cycle active inspiration phases with passive exhalation phases, or the device can be used in a "Manual Mode," which allows the rescuer to manually initiate (and terminate) the inspiratory phase with the manual press and release of the O2 release button (colored gold in the photo). Also capable of providing passive oxygen with an "Inhalator Mode," which passively supplies 15 L/min on activation (separate control knob not visible in photo). Similarly, the practice of noninvasive airway management will benefit emergency medicine and critical care practitioners in assuring adequate oxygenation during invasive airway procedures. Understanding the advantages, disadvantages, and limitations of various airway management techniques continues to be a cornerstone of a safe and effective practice of airway management in anesthesiology, emergency medicine, and critical care medicine as well as prehospital airway management. Expiratory upper airway obstruction caused by the soft palate during bag-mask ventilation. Effect of progressive mandibular advancement on pharyngeal airway size in anesthetized adults. The respiratory system during resuscitation: a review of the history, risk of infection during assisted ventilation, respiratory mechanics, and ventilation strategies for patient with unprotected airway. Part 6: alternative techniques and ancillary devices for cardiopulmonary resuscitation. Advanced airway management does not improve outcome of out of hospital cardiac arrest. Ultrasound assessment of the position of the tongue during induction of anaesthesia. Evolution of changes in upper airway collapsibility during slow induction of anesthesia with propofol. Upper airway closure: a primary source of difficult ventilation with sufentanil induction anesthesia. Pharyngeal function and airway protection during subhypnotic concentrations of propofol, isoflurane and sevoflurane. Aging influences on pharyngeal anatomy and physiology: the predisposition to pharyngeal collapse. Short thyromental distance is a surrogate for inadequate head extension, rather then small submandibular space, when indicating possible difficult direct laryngoscopy. Effects of general anesthesia and paralysis on upper airway changes due to head position in humans. Motion generated in the unstable upper cervical spine during head tilt-chin lift and jaw thrust maneuvers. Upper airway obstruction by the soft palate: influence of position of the head, jaw and neck. E-O technique is superior to E-C technique in manikins during single person bag mask ventilation performed by novice. An evaluation of bag-valvemask ventilation using an ergonomically designed face mask among novice users: a simulation-based pilot study. Accuracy of manual ventilation: comparison of closed and semiclosed breathing systems. An updated report by the American Society of Anesthesiologists Task Force on management of the difficult airway. Real time detection of gastric insufflation related face mask pressure-controlled ventilation using ultrasonography of the antrum and epigastric auscultation in nonparalyzed patients. Effect of smaller tidal volumes during basic life support ventilation in patients with respiratory arrest: good ventilation, less risk. Comparison of three modes of positive pressure mask ventilation during induction of anesthesia: a prospective, randomized, crossover study. Incidence, predictors and outcome of difficult mask ventilation combined with difficult laryngoscopy. Upper lip bite test as a predictor of difficult mask ventilation: a prospective study. Pharyngeal patency in response to advancement of the mandible in obese anesthetized persons. Anatomy of pharynx in patients with obstructive sleep apnea and in normal subjects. The effect of leaving dentures in place on bag mask ventilation at induction of general anesthesia. The effect of wrist position, angular velocity, and exertion direction on simultaneous maximal grip force and wrist torque under the isokinetic conditions. Carpal tunnel syndrome in female nurse anesthetists versus operating room nurses: prevalence, laterality and impact of handedness. Body posture during simulated tracheal intubation: GlideScope videolaryngoscopy vs Macintosh direct laryngoscopy for novices and experts. The sniffing position provides greater occipito-atlanto-axial angulation than simple head extension: a radiological study. Optimal combination of head, mandible and body positions for pharyngeal airway maintenance during perioperative period: lesson from pharyngeal closing pressures. Use of elevation pillow to produce the head-elevated laryngoscopy position for airway management in morbidly obese and large-framed patients. How can we improve mask ventilation in patients with obstructive sleep apnea during anesthesia induction Effects of muscle relaxants on mask ventilation in anesthetized persons with normal upper airway anatomy. Evaluation of changes in tidal volume during mask ventilation following administration of neuromuscular blocking drugs. The effect of neuromuscular blockade on the efficiency of mask ventilation of the lungs. Should anesthetists have to demonstrate that face mask ventilation is possible before giving a neuromuscular blocker Mechanical ventilation and resuscitation under water: Exploring one of the last undiscovered environments-A pilot study. An inflatable mask is fitted with a tube that exits the mouth to enable ventilation of the lungs. This placement is intended to be a less traumatic alternative to intubation, although more reliable and hands off than face mask ventilation. Selection of an appropriate airway device across and within device subtypes is complex and informed by multiple factors specific to the patient, surgery, and practitioner. With no single ideal airway device, advanced airway management depends on a repertoire incorporating many airway devices, as recognized in the various international difficult airway algorithms. The cuff incorporates a "traffic light" system that enables continuous monitoring of cuff pressure during use. The concept of being supraglottic describes the fact that the ventilation orifice is just above the glottis, in contrast to pharyngeal airway devices, or infraglottic devices that deliver anesthetic gases or oxygen below the vocal cords. In 2004, Brimacombe recommended use of the term extraglottic to highlight that distal extension into the hypopharynx and upper esophagus, below the level of the glottis, is a fundamental safety feature of supraglottic devices. Two narrow airway tubes run on either side of the drain tube, which passes through the modified cuff. A full review of the extensive body of literature and devices (particularly the various disposable laryngeal mask variants) is beyond the scope of a single chapter.

In a large medicine for high blood pressure cheap zofran 8mg without a prescription, prospective observational multicenter study symptoms 5dp5dt fet generic zofran 8mg free shipping, Theiler and colleagues159 reported 2049 uses of the i-gel medicine used for pink eye 8mg zofran for sale. Factors associated with primary ventilation failure were male gender medicine 1800s best purchase zofran, impaired mandibular subluxation medicine and manicures zofran 8 mg with visa, poor dentition medicine bow national forest effective 8mg zofran, and older age. There was no significant difference between the airway leak pressures of the two devices (25 cm H2O for the i-gel vs. Patients weighing 80 to 90 kg were more likely to experience postoperative sore throat and dysphagia. The investigators suggested the larger size might be restricted to patients heavier than 90 kg. The most common airway manipulation necessary to achieve an effective airway with the i-gel was increasing the depth of insertion. The anatomic position, evaluated with a fiberoptic view score, was significantly better with the i-gel. Blind intubation through the i-gel had also a very low success rate in patients presenting at least one criteria for difficult intubation, as reported by Theiler and colleagues. The i-gel presented the advantage of a shorter time for intubation and better glottis visualization. The i-gel has been used in difficult airway management, including for subglottic stenosis178 as a conduit for elective intubation in patients with predicted difficult airway. Donald Miller and launched at the Second All Africa Congress in 2002 and again in Europe in 2004. It is hollow, with a collection chamber (50-mL capacity) designed as a reservoir for trapping pharyngeal secretions and potential regurgitated gastric contents. It has a shape of a boot that lines the pharynx, with a toe, bridge, and heel and an anterior airway aperture. After correct positioning, the toe sits in the esophagus, the bridge at the base of the tongue, and the heel anchors the device between the esophagus and nasopharynx. Moving the jaw forward with the thumb and finger and flattening the hollow chamber can facilitate insertion. Because it can be flattened, it is particularly useful in the case of limited jaw opening. The oropharyngeal leak pressure and peak inspiratory pressures increased significantly after gas insufflation, but no signs of gastric insufflation were detected by visual inspection of the stomach through the laparoscope. The overall insertion success rate was 100% when used by the principal investigator and 92. Complications An increased incidence of airway trauma as indicated by blood staining of the device after removal and sore throat has been reported. Because it is cuffless, there is enhanced simplicity of use, but a careful selection of the appropriate size is advised. More clinical evidence is needed to determine whether or not this feature reduces the incidence of aspiration. The first clinical observational trial with the Baska Mask was performed by Alexiev and colleagues204 and included 30 women scheduled for elective minor surgery. All insertions were performed by the principal investigator, who had very limited prior experience with the Baska Mask. The learning curve to insert the Baska Mask was short, with notable improvement in the checked parameters noted after the first 10 patients. Complications the Baska Mask is a new device, and therefore it is premature to discuss potential complications associated with it. Alexiev and colleagues205 reported that repeated adjustment of the depth of insertion was necessary to obtain a good airway seal. The uniqueness of the device lies in its noninflatable expanding membranous cuff balloon. Because of its unique design, it may be particularly useful in clinical situations where the airway seal is more important than ease of insertion. In addition, there are two drain tubes for gastric fluid drainage, situated on each side of the ventilation tube, and opening in the large distal aperture located at the upper esophagus. An inbuilt hand "tab" is attached to the cuff and can be used to manually increase the angulation of the device for easier insertion. The Baska Mask is provided in single-use and multiuse versions and four sizes from small to large adult with color-coded connectors. Before insertion, the Baska Mask should be checked for integrity by sealing and compressing both ends of the device. The device should be lubricated generously on both sides with water-soluble jelly. The proximal part of the mask is compressed between the thumb, the forefinger, and the middle finger and advanced toward the hard and soft palate until resistance is encountered. If difficulties ventilating the patient are encountered, the insertion depth needs to be adjusted or the Baska Mask replaced with a different size. One of the drain tubes can be connected to a suction device for continuous or intermittent pharyngeal suction during insertion or removal of the device. Existing literature supports their safe use, emphasizing the importance of appropriate patient selection and atraumatic insertion. Limiting the intracuff pressure to 60 cm H2O significantly increases the safety profile. Continued research in this field will drive airway management to higher safety standards. Comparison of the EasyTube and endotracheal tube during general anesthesia in fasted adult patients. An evaluation of the laryngeal tube during general anesthesia using mechanical ventilation. This is not applicable in emergency situations, but the intracuff pressure can be monitored after insertion, especially for procedures lasting more than 60 minutes. Ventilation with the esophageal tracheal Combitube in cardiopulmonary resuscitation: promptness and effectiveness. The incidence of gastroesophageal reflux and tracheal aspiration detected with pH electrodes is similar with the Laryngeal Mask Airway and Esophageal-Tracheal Combitube-A pilot study. Evolution of the extraglottic airway: a review of its history, applications, and practical tips for success. Failed rapid sequence intubation in trauma patients: esophageal tracheal Combitube is a useful adjunct. Replacing the combitube by an endotracheal tube using a fibre-optic bronchoscope during spontaneous ventilation. Airway management in a case of neck impalement: use of the oesophageal tracheal Combitube airway. Laryngeal mask airway and bougie intubation failures: the Combitube as a secondary rescue device for in-hospital emergency airway management. Waste gas exposure to sevoflurane and nitous oxide during anesthesia using the oesophageal-tracheal Combitube small adult. Fiberoptic-guided airway exchange of the esophageal-tracheal Combitube in spontaneously breathing versus mechanically ventilated patients. Retrograde intubation around an in situ Combitube: a difficult airway management strategy. Acute upper airway obstruction by an overinflated Combitube esophageal obturator balloon. Choice of airway devices for 12,020 cases of nontraumatic cardiac arrest in Japan. Complications associated with the Esophageal-Tracheal Combitube in the pre-hospital setting. Complications following the use of the Combitube, tracheal tube and laryngeal mask airway. Speed of insertion of seven supraglottic airway devices by medical students: superiority of Combitube and EasyTube under simulated pathological airway conditions. Airway management by paramedics using endotracheal intubation with a laryngoscope versus the oesophageal tracheal Combitube and EasyTube on manikins: a randomised experimental trial. Performance and skill retention of intubation by paramedics using seven different airway devices-a manikin study. Prospective randomized comparison between EasyTube and Esophageal Tracheal Combitube during general anesthesia with mechanical ventilation. Randomized comparison of laryngeal tube with classic laryngeal mask airway for anaesthesia with controlled ventilation. A comparison of the laryngeal tube with the laryngeal mask airway during routine surgical procedures. The laryngeal tube compared with the laryngeal mask: insertion, gas leak pressure and gastric insufflation. A comparison of the laryngeal mask airway ProSeal and the laryngeal tube airway in paralyzed anesthetized adult patients undergoing pressurecontrolled ventilation. A comparison of the Proseal Laryngeal Mask and the Laryngeal Tube in spontaneously breathing anesthestetized patients. Comparison of the disposable vs the reusable laryngeal tube in paralysed adult patients. Use of the laryngeal tube in two unexpected difficult airway situations: lingual tonsillar hyperplasia and morbid obesity. The laryngeal tube for airway management in adult patients with pharyngeal and laryngeal tumors-a pilot study. Assessment of the use of the laryngeal tube for cardiopulmonary resuscitation in a manikin. Airway management in cardiac arrest-comparison of the laryngeal tube, tracheal intubation and bag-valve mask ventilation in emergency medical training. Intubating laryngeal mask airway, laryngeal tube, 1100 ml self-inflating bag-alternatives for basic life support A comparison of the laryngeal tube and bag-valve mask ventilation by emergency medical technicians: a feasibility study in anesthetized patients. Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Ventilation with the laryngeal tube in paediatric patients undergoing elective ambulatory surgery. Randomized controlled trial comparing the laryngeal tube and the laryngeal mask in pediatric patients. Prospective, randomized comparison of laryngeal tube and laryngeal mask airway in pediatric patients. Large cuff volumes impede posterior pharyngeal mucosal perfusion with the laryngeal tube airway. Storage capacities of the laryngeal mask and laryngeal tube compared and their relevance to aspiration risk during positive pressure ventilation. A randomized controlled trial comparing the ProSeal Laryngeal Mask Airway with the Laryngeal Tube Suction in mechanically ventilated patients. The influence of head and neck position on the oropharyngeal leak pressure and cuff position of three supraglottic airway devices. Use of the laryngeal tube-S for airway management and prevention of aspiration after a failed tracheal intubation in a parturient. Out-of-hospital airway management by paramedics and emergency physicians using laryngeal tubes. Airway control in case of a mass toxicological event: superiority of second-generation supraglottic airway devices. Gastro-Laryngeal Tube for endoscopic retrograde cholangiopancreatography: a preliminary report. The Gastro-Laryngeal Tube for interventional endoscopic biliopancreatic procedures in anesthetized patients. Randomised comparison of the Classic Laryngeal Mask Airway with the Cobra Perilaryngeal Airway during anaesthesia in spontaneously breathing adult patients. A prospective, randomized comparison of cobra perilaryngeal airway and laryngeal mask airway unique in pediatric patients. Video assessment of supraglottic airway orientation through the perilaryngeal airway in pediatric patients. Cobra perilaryngeal airway as a rescue device for failed rapid sequence intubation. Successful anesthetic management of a child with blepharophimosis syndrome and atrial septal defect for reconstructive ocular surgery. An evaluation of the Cobra perilaryngeal airway: study halted after two cases of pulmonary aspiration. A randomized controlled trial comparing the cuffed oropharyngeal airway and the laryngeal mask in spontaneous breathing anesthetized adults. A pilot study to examine the effect of the Tulip oropharyngeal airway on ventilation immediately after mask ventilation following the induction of anaesthesia. Intraocular pressure and haemodynamic responses to insertion of the i-gel, laryngeal mask airway or endotracheal tube. In vitro study of magnetic resonance imaging artefacts of six supraglottic airway devices. Initial anatomic investigations of the I-gel airway: a novel supraglottic airway without inflatable cuff. Oesophageal seal of the novel supralaryngeal airway device I-Gel in comparison with the laryngeal mask airways Classic and ProSeal using a cadaver model. A new single use supraglottic airway device with a noninflatable cuff and an esophageal vent: an observational study of the i-Gel. A randomised crossover trial comparing the i-gel supraglottic airway and classic laryngeal mask airway. Comparison of the Intersurgical Solus laryngeal mask airway and the i-gel supralaryngeal device.