Introduction
The airway devices are an integral component of day-to-day anesthesia practice. The airway devices provide oxygen to the patient and may vary from noninvasive devices like nasal prongs to invasive ones like an endotracheal tube. These devices are used in the operating room, postoperative and procedural suites, and intensive care units. This chapter is an overview of the most commonly used airway types of equipment in anesthesia practice.
Face Masks
A face mask acts as an interface for the patient’s ventilation without introducing any apparatus into the patient’s airway. Mask ventilation is a basic skill for any anesthesiologist. Previously used for administering the whole anesthesia, face masks are now used only for a short time before the placement of a definitive airway or in an emergency. The face mask can be made up of many different substances such as black rubber, plastic, or some elastic material. They are of many sizes which can fit patients of different ages and sizes. Any face mask consists of three main body parts, namely (Fig. 46.1):
Body: The body, also called the dome, is the main part of the mask. With a transparent body, the newer masks allow for visualization of the lips of the patient, secretions, blood, and exhaled moisture. It can also be better acceptable to the patient.
Seal: Seal is the rim or edge of the face mask, which comes in direct contact with the patient’s face. It can be either a flap type, which is the direct extension of the body, assumes the shape of the face upon pressing, or the cushion type, which is filled with air or material which provides the seal.
Connector: The connector is the opposite end of the seal attached to the circuit. It is made up of a thickened fitting of 22 mm internal diameter, which gets connected to a resuscitation bag or a circuit.
Types of Masks
Rendell–Baker–Soucek (RBS) Mask
This mask has a triangular body, is specifically designed to fit pediatric patients, and has low dead space (Fig. 46.2). Some masks are scented, and few have a pacifier. This can also be used for ventilating a patient through the stoma of tracheostomy.
Endoscopy Mask
This mask has a port or diaphragm that allows passage of fiberoptic endoscope and facilitates ventilating the patient during endoscopy (Fig. 46.3).
Techniques of Use
The face mask should form a tight seal around the patient’s face to facilitate ventilation. So, appropriate size selection is the first step in mask ventilation. Various techniques of use of face mask are briefly described below.
In this method, the anesthesia provider holds the mask in either of the hand over the patient’s face. The thumb and the index finger are pressed over the body of the mask, which forms a “C,’’ and pressure is applied over the patient’s face. The remaining three fingers are placed over the mandible, one at the angle of the mandible, one over the body, and the other at the mentum forming an “E.’’ Care should be taken to avoid compression over the eyes or into the soft tissue, which can itself act as an obstruction during ventilation.
The other method is a two-handed technique with another anesthesiologist ventilating the patient. The person who is holding the mask has to place the mask over the patient’s face and keep it firm with C and E technique as described earlier with both the hands.
Airways
Airways are the devices that help in lifting the tongue and epiglottis away from the posterior pharyngeal wall, thereby preventing the collapse of the airway. It can be achieved via oral or nasal route.
Various other uses of airways include:
Preventing biting or occlusion of the endotracheal tube.
Protect from tongue bite during the seizure.
Oropharyngeal Airways
It is a curved instrument made up of metal, plastic, or rubber. There is a proximal flange that can be used to fix the airway, thereby preventing from inserting the airway too deep into the airway. Flange continues distally as a bite portion, which is hard and lies in between the lips and teeth. The pharyngeal end is curved and corresponds to the shape of the tongue and palate.
Guedel Airway
It is a hollow oropharyngeal airway with a large flange and reinforced bite portion. It has a gentle curve that follows the contour of the tongue (Fig. 46.4). The hollow part is used for suctioning.
Berman Airway
This airway has the sides cut open, and there is support in the center giving it H-shaped cross-section (Fig. 46.5). The open ends allow the tracheal tube to pass and allow suction. It is easier to clean and less likely to be impacted by the foreign body or mucous.
Safar Airway
This S-shaped airway consists of two Guedel airways attached to each side with a flange (Fig. 46.6). It is designed for mouth-to-mouth ventilation.
Technique for Use
The oral airway is considered to be of appropriate size if it corresponds to the vertical distance between the patient’s incisor and the angle of the jaw. If it is too small, it can cause kinking of the tongue, hindering ventilation. It can cause trauma to the larynx or displace epiglottis, causing airway obstruction if it is too big. It is inserted in the mouth with curvature facing the upper lips. Once it is advanced midway, it is rotated to its normal position and advanced further till it attains its position.
Nasopharyngeal Airway
Nasopharyngeal airways serve the same purpose as oral airways but are inserted via nostrils. They are soft, pliable, and made up of latex rubber or polyurethane. It has a flange at the proximal end, which is used for fixation of the device, followed by a long, curved body that fits into the nasal cavities (Fig. 46.7). The distal end has a bevel that helps in the easy passage and less traumatic insertion. It is available in different sizes and internal diameters.
Technique of Use
The length of the airway can be estimated by measuring the distance between the tragus of the ear to the tip of the nose. The distal end of the airway has to be well lubricated before insertion, and using vasoconstrictor nasal drops prevents bleeding. It is inserted with bevel end first and passed vertically along the floor of the nose with twisting action. The curve of the airway should be directed toward the patient’s feet as it is going inside.
Nasal airways are better tolerated in awake patients and are less likely to be accidentally displaced. They are useful in patients with limited mouth opening, fragile dentition, or oral pathology.
The complications are almost similar to that of the oral airways, except that nasal bleeding is a possibility. They are absolutely contraindicated in patients with facial fractures (including basal skull fractures) and coagulopathy.
AMBU Bag Resuscitator
Manual resuscitators are portable ventilating devices used for ventilation of the patients during:
There are various types of resuscitators such as artificial manual breathing unit (AMBU) bag resuscitator; Laerdal resuscitator bag of which AMBU bag resuscitator is the most widely used. AMBU is available in three sizes, namely, the following:
Manual resuscitators have a self-expandable bag that is compressible, a bag refill valve, and a nonbreathing valve at the patient end (Fig. 46.8). Neonatal and child sizes also have a pressure relief valve that opens at a pressure greater than 40 cm H2O and prevents barotrauma. A reservoir bag is also provided with the bag, which increases the FiO2 delivered.
You may also need
CHAPTER 15 Anesthesia for Respiratory Diseases
CHAPTER 30 Anesthesia for ENT Surgery
CHAPTER 47 Oxygen Delivery Devices
CHAPTER 33 Nonoperating Room Anesthesia (AS4.7)
CHAPTER 38 Complications in Anesthesia
CHAPTER 31 Anesthesia in Trauma Patients
CHAPTER 43 Basics of Ventilator
CHAPTER 44 Intensive Care Unit