Air Way Maintenance Using Oral/Nasal Airway Device With Face Mask
Air Way Maintenance Using Oral/Nasal Airway Device With Face Mask
Oropharyngeal or nasopharyngeal airways (5.4 and 5.5) help to maintain a clear airway by displacing the tongue and other tissue from the posterior portion of the hypopharynx.
Loss of upper airway muscle tone in anesthetized patients allows the tongue and epiglottis to fall back against the posterior wall of the pharynx. Repositioning the head or a jaw thrust is the preferred technique for opening the airway as it is explained previously. To maintain the opening an artificial airway can be inserted through the mouth or nose to create an air passage between the tongue and the posterior pharyngeal wall.
Selecting the correct size is important (Figure 5.4). Too small an air way may cause the tongue to kink and force part of it against the roof of the mouth, causing obstruction. Too large an airway may cause obstruction by displacing the epiglottis posteriorly and may traumatize the larynx. The correct size can be estimated by holding the airway next to the patient's mouth. The tip should rest cephalad to the angle of the mandible. The best criterion for proper size and position is unobstructed gas exchange. A typical adult female will take an 8-cm oral air way, and an adult male, 9 or 10 cm. If the airway repeatedly comes out of the mouth, it should be removed and a smaller size tried.
The Oropharyngeal Airway
It should be lubricated and gently inserted. Only water based lubricating gels should be used. Insert the airway with the tip facing up (Figure 5.4). Then rotate the oral airway into position in the pharynx. Ensure that the patient is adequately anesthetized. If the patient is not anesthetized this may cause choking, coughing, or gagging. Never force an oral airway into place. This may cause trauma and bleeding. Alternatively, an oral airway can be inserted tip down with the aid of a tongue depressor.
A Nasal Airway
It can be used in a patient who has difficulty opening their mouth (Figure 5.5 the fourth image). It should be lubricated and gently inserted. Only water based lubricating gels should be used. Do not force a nasal airway or a serious nose bleed may occur. Do not place a nasopharyngeal airway in patients with facial or nasal fractures, anticoagulated patient and hypertrophied tonsil. Placing a nasopharyngeal airway is not as stimulating as an oral airway. If a nasal airway is not available then an endotracheal tube can be used. It should be inserted so that the tip is above the epiglottis. The length of a nasal airway can be estimated as the distance from the nares to the meatus of the ear, and should be approximately 2 - 4 cm longer than oral airways.
The use of an oral or nasal airway is helpful in the management of patients recovering from general anesthesia. An artificial airway should be used in combination with a recovery position. The semi-prone position helps to prevent secretions from causing a laryngospasm, coughing, and possible airway occlusion. The use of oral and nasal airways, with the recovery position (Figure 5.6), does not replace good care of the patient.
The anesthesia provider should remain with the patient until they are awake enough to maintain their own airway. If the patient does not maintain adequate respiration and ventilation, then intubation and/or assistance with a bag-mask-valve device should be considered. The patient should never be left unmonitored.
The use of a face mask (Figure 5.7) can facilitate delivery of oxygen or of an anesthetic gas from a breathing system to a patient by creating an airtight seal with the patient's face. Facemasks are available in a variety of sizes. The rim of the mask is contoured and conforms to a variety of facial features. The mask's 22-mm orifice attaches to the breathing circuit of the anesthesia machine through a right-angle connector. Clear masks have the benefit of allowing visualization of fogging, skin color, and signs of regurgitation.
Several mask designs are available. Transparent masks allow observation of exhaled humidified gas and immediate recognition of vomiting. Black rubber masks are pliable enough to adapt to uncommon facial structures. Retaining hooks surrounding the orifice can be attached to a head strap so that the mask does not have to be continually held in place (Figure 5.8).
Most facemasks come with a hooked rim around the 15- to 22-mm fitting that attaches to the anesthesia breathing. Much attention has focused on devices to avoid the problem of difficult tracheal intubation.
Failure to place an endotracheal tube is not the actual cause of the severe adverse outcomes related to difficult airway management. The primary problem is an inability to oxygenate, ventilate, prevent aspiration, or a combination of these factors. Prospectively identifying patients at risk for difficult facemask ventilation, ensuring the ability to ventilate the patient's lungs before administering longer acting anesthetics and neuromuscular blocking drugs, and developing proficient facemask ventilation skills are critical to the practice of anesthesia.
Effective ventilation requires both a face-tight mask fit and a patent airway. Improper face mask technique can result in continued deflation of the anesthesia reservoir bag when the adjustable pressure-limiting valve is closed, usually indicating a substantial leak around the mask. In contrast, the generation of high breathing-circuit pressures with minimal chest movement and breath sounds implies an obstructed airway. Both these problems are usually resolved by proper technique (Figure 5.9 and 5.10).
Achieving Seal With Face Mask
1. Place the mask strap beneath the occiput.
2. Apply the mask's nasal groove to the low point of the nasal bridge to avoid pressure on the eyes.
3. Grip the left mandible with the third and fourth fingers of the left hand.
4. Lower the mask so that its inferior rim contacts the face between the lower lip and the mental prominence.
5. If there is a leak between the mask and the cheeks, consolidate the seal by dragging mobile tissue of the left cheek toward and under the mask cushion, stabilizing the tissue with the ulnar margin of the left hand.
6. Bracing the mentum against the mask, pull the mandible up and forward with the third through fifth fingers, while the thumb and index finger grip the mask above and below the connector.
7. Maintaining the left-sided seal, tilt the mask toward the right cheek, consolidating the seal by dragging the mobile tissue forward to the cushion and by keeping it there with one limb of the mask strap.
8. The other limbs of the mask strap may improve the seal, especially for anesthetists with small hands. Crossing the lower limbs of the mask strap prevents the mask from riding up the face.
The Bag-Valve Mask (BVM) Ventilation
BVM device (Figure 5.11) is used to manually deliver positive pressure through an applied face mask, extraglottic device or endotracheal tube. The former would be an initial step in an apneic or hypoventilating patient, and is almost always indicated prior to, or during intubation of an ill patient. The clinician should be intimately familiar with the workings of the BVM device, as it has a number of valves, and needs proper assembly to work. Also known as manual resuscitators, these devices incorporate a self-inflating bag, a one-way bag inlet valve, and a nonrebreathing patient valve. The patient valve end features a universal connector with a 22-mm outside diameter (OD), which fits standard face masks, and a 15-mm internal diameter (ID) that connects to standard endotracheal tubes, extraglottic devices,and cricothyrotomy or tracheostomy cannulae.
An oxygen inlet port is located on the bag inlet valve end to accept the oxygen source tubing. To enable 100% oxygen delivery, oxygen flow must be adjusted to ensure the attached reservoir bag never fully collapses. The face mask used in conjunction with the manual resuscitator is generally made of rubber or plastic, and may incorporate an inflatable cuff around its margin to better conform to the patient's facial anatomy. The tight seal thus afforded is mandatory when the manual resuscitator is being used for PPV, but is also useful in the spontaneously breathing patient, as the good seal obtained ensures delivery of close to 100% oxygen (Figure 5.12).
Adult-sized manual resuscitators are supplied with a 1600 mL self-inflating bag; child size 500 mL; and infant 240 mL. The pediatric sized BVM devices may have an additional valve just proximal to the face mask a pressure limiting or "pop-off" valve. This is calibrated to release applied airway pressure at approximately 40 cm H2O, to help prevent baro-trauma. In clinical situations where there is a recognized airway obstruction that is not readily reversible (e.g., epiglottis, croup, airway edema, severe asthma), the pop-off valve may need to be controlled manually to ensure continued lung inflation.