[Objective 7]
Adequate oxygenation requires an open airway and adequate air exchange. After the airway has been opened, determine whether the patient ’s breathing is adequate or inadequate. If ventilatory efforts are inadequate, the patient ’s breathing may be assisted by forcing air into the lungs (ie, delivering positive pressure ventilations). NPPV, mouth-to-mask ventilation, and BMV are examples of methods that may be used to deliver positive pressure ventilation.
Noninvasive Positive Pressure Ventilation [Objectives 7, 8]
NPPV, also called noninvasive ventilation (NIV), is the delivery of ventilatory support to a spontaneously breathing patient without using an invasive artificial airway (eg, ETT, tracheostomy tube). NPPV has
TABLE 2.3 Oral and Nasal Airways
Considerations Oral Airway Nasal Airway
Indications • Helps maintain an open airway in an unresponsive patient with no gag reflex who is not intubated
• Helps maintain an open airway in an unresponsive patient with no gag reflex who is being ventilated with a bag-mask or other positive pressure device
• May be used as a bite block after insertion of a tracheal tube or orogastric tube
• To aid in maintaining an airway when use of an oral airway is contraindicated or difficult to place such as when the patient ’s jaw is clenched during a seizure or if oral trauma is present
Contraindications • Responsive patient with an intact gag reflex
• Severe craniofacial trauma
• Patient intolerance Sizing • Corner of the mouth to the tip of the
earlobe or the angle of the jaw
• Tip of nose to the angle of the jaw or the earlobe
Advantages • Positions the tongue forward and away from the back of the throat
• Easily placed
• Provides a patent airway
• Tolerated by responsive patients
• Does not require the mouth to be open Disadvantages • Does not protect the lower airway from
aspiration
• May produce vomiting if used in a responsive or semiresponsive patient with a gag reflex
• Does not protect the lower airway from aspiration
• Improper technique may result in severe bleeding; resulting epistaxis may be difficult to control
• Suctioning through the device is difficult
• Although tolerated by most responsive and semiresponsive patients, can stimulate the gag reflex in sensitive patients, precipitating vomiting, gagging, or laryngospasm Precautions • Use of the device does not eliminate the
need for maintaining proper head position
• Use of the device does not eliminate the need for maintaining proper head position
been effectively used to avoid or decrease the rates of endotracheal intubation and to improve outcomes (eg, reduce rates of mortality, decrease duration of hospital stays) in patients with severe exacerbations of COPD or acute cardiogenic pulmonary edema, in immunosuppressed patients with acute respiratory distress or failure, and as an adjunct to early liberation from mechanical ventilation in patients who have COPD (Keenan, et al., 2011). In general, the best candidates for NPPV are cooperative, able to protect their airway, and are hemodynamically stable (Liesching, et al., 2003).
Although a number of interfaces are available, the patient typically wears a nasal mask, oronasal mask, or full face mask equipped with straps to hold the mask firmly in place. Ventilatory support is provided by means of a portable or standard ventilator.
The term noninvasive positive pressure ventilation encompasses various modes of positive pressure ven-tilation including CPAP and BPAP, but these modes of NPPV are distinctly different. With noninva-sive CPAP, a continuous pressure that is greater than atmospheric pressure is delivered throughout the respiratory cycle. CPAP provides airway support by splinting open the upper airway, increasing lung volume, and increasing intrathoracic pressure, but it does not decrease the workload of the patient ’s inspi-ratory muscles during breathing (Hess, 2013). Because CPAP is helpful in improving alveolar oxygen-ation, it is more effective in hypoxemic conditions (eg, heart failure) than in hypercapnic states. When BPAP is administered, two levels of pressure are applied; a higher pressure is used during inspiration (ie, inspiratory positive airway pressure) and a lower pressure is used during expiration (expiratory positive airway pressure), thus decreasing the patient ’s inspiratory muscle workload. BPAP is useful in hypercap-nic failure (eg, exacerbations of COPD) as well as in mixed hypoxic and hypercaphypercap-nic failure. Contrain-dications for NPPV are shown in Box 2.7.
ACLS Pearl
Because BPAP is themost commonmode used with NPPV, some clinicians usethe terms BPAP and NPPV synonymously.
Mouth-to-Mask Ventilation [Objectives 7, 9]
The device used for mouth-to-mask ventilation is commonly called a pocket mask, pocket face mask, ven-tilation face mask, or resuscitation mask. A pocket face mask is a clear, semirigid mask that is sealed around
BOX 2.7 Noninvasive Positive Pressure Ventilation
—
Contraindications• Cardiac arrest
• Complete upper airway obstruction
• Excessive secretions
• Facial trauma or deformity
• Hemodynamic instability
• High risk for aspiration
• Inability to fit mask
• Inability to protect airway
• Recent facial, esophageal, or gastric surgery
• Respiratory arrest
• Uncontrolled vomiting
• Uncooperative patient
Fig. 2.23 Pocket mask. (Courtesy Laerdal Medical.)
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CHAPTER 2 Airway Management
the patient ’s mouth and nose (Fig. 2.23). Masks used for ventilation should be made of transparent mate-rial to allow assessment of the patient ’s lip color and detection of vomitus, secretions, or other substances and they should be equipped with an oxygen inlet and a standard connector that enables connection to a bag-mask (or other ventilation) device.
When ventilating with a patient using a pocket mask, connect a one-way valve to the ventilation port on the mask. If an oxygen inlet is present on the mask and oxygen is available, connect oxygen tubing to the oxygen inlet, and set the flow rate at 10 to 12 L/min.
Position yourself at the patient ’s head or side. Positioning yourself directly above the patient ’s head allows you to watch the patient ’s chest while delivering ventilations. This position is used if the patient is in respiratory arrest (but not cardiac arrest) or when two-rescuer cardiopulmonary resuscitation (CPR) is being performed. If you are by yourself, positioning yourself at the patient ’s side allows you to maintain the same position for both rescue breathing and chest compressions.
Open the patient ’s airway. If needed, clear the patient ’s airway of secretions or vomitus. If the patient is unresponsive and has no gag reflex, insert an oral airway. Select a mask of appropriate size and place it on the patient ’s face. A mask of correct size should extend from the bridge of the nose to the groove between the lower lip and chin. If the mask is not properly positioned and a tight seal main-tained, air will leak from between the mask and the patient ’s face, thereby resulting in the delivery of less tidal volume to the patient. Less tidal volume results in less lung inflation, which means less oxygenation.
The E-C clamp technique, also called the E-C grip, can be used to create a good face-to-mask seal and provide effective ventilation (Fig. 2.24). Apply the narrow portion (ie, apex) of the mask over the bridge of the patient ’s nose and stabilize it in place with your thumbs. Lower the mask over the patient ’s face and mouth. Use your index fingers to stabilize the wide end (ie, base) of the mask over the groove between the patient ’s lower lip and chin. When properly positioned, your thumb and index finger will create a
“C.” Gently push down on the mask to establish an adequate mask seal. Position your remaining fingers along the angle of the jaw to form an “E.” Use these fingers to lift the jaw and pull the patient ’s chin into the mask.Ventilate thelungs through theone-way valveon thetop of themaskat a rate of onebreath every 5 to 6 seconds, or about 10 to 12 breaths/min. Deliver each breath over 1 second and stop ventilation when gentle chest rise is observed.
ACLS Pearl
Gastric distention is a complication of positive pressure ventilation that can lead to vomiting and subsequent aspiration. Gastric distention also restricts movement of the diaphragm, impeding ven-tilation, and decreases the effectiveness of CPR if the patient is in cardiac arrest.
Another method used for ventilation is the thenar eminence (TE) technique, also called the TE grip.
When the TE method is used, the TEs of both hands are used to hold the mask in place (Fig. 2.25). The rescuer ’s fingers are positioned under the angle of the patient ’s mandible to perform a jaw lift (Fig. 2.26).
Research has shown that use of the TE technique is easier for inexperienced providers and results in improved ventilation compared with the E-C clamp technique (Gerstein, et al., 2013). Indications, advantages, and disadvantages of mouth-to-mask ventilation are shown in Table 2.4.
Fig. 2.24 The E-C clamp technique for mouth-to-mask or BMV. (From Roberts J: Roberts and Hedges ’ clinical procedures in emergency medicine , ed 6, Philadelphia, 2014, Saunders.)
Bag-Mask Ventilation [Objective 7]
A BMDis a self-inflatingbag witha nonrebreathing valvemechanism(Fig.2.27).ABMDmayalsobereferred toasa bag-mask, bag-valve-mask device or bag-maskresuscitator (whenthemaskisused),orasa bag-valvedevice (when the mask is notused [ie, when ventilating a patient with a tracheal tube or tracheostomy tube in place]).
The BMD should be equipped with a transparent disposable plastic mask with a high-volume, low-pressure cuff; standard fittings to allow forattachment of the device to a standard mask, advanced airway, or other ven-tilationdevice; andan oxygen-collectingdevice (ie,reservoir)to allowdeliveryof highconcentrations of oxygen.
Oxygen Delivery [Objective 9]
When using a BMD, the amount of delivered O2 is dependent on the ventilatory rate, the volume deliv-ered during each breath, the O2 flow rate into the ventilating bag, the filling time for the reservoir bag,
TABLE 2.4 Mouth-to-Mask Ventilation
Inspired Oxygen Concentration
• Without supplemental oxygen equals about 16% to 17% (exhaled air)
• Mouth-to-mask breathing combined with supplemental oxygen at a minimum flow rate of 10 L/min equals about 50%
Advantages • Esthetically more acceptable than mouth-to-mouth ventilation
• Easy to teach and learn
• Physical barrier between the rescuer and the patient ’s nose, mouth, and secretions
• Reduces (but does not prevent) the risk of exposure to infectious diseases
• Use of a one-way valve at the ventilation port decreases exposure to the patient ’s exhaled air
• If the patient resumes spontaneous breathing, the mask can be used as a simple face mask to deliver 40% to 60% oxygen by giving supplemental oxygen through the oxygen inlet on the mask (if so equipped)
• Can deliver a greater tidal volume compared with a BMD
• Rescuer can feel the compliance of the patient ’s lungs (compliance refers to the resistance of the patient ’s lung tissue to ventilation)
Disadvantages • Rescuer fatigue
• Possible gastric distention
Fig. 2.27 Bag-mask devices. (Courtesy Laerdal Medical.) Fig. 2.25 The thenareminences of both hands of there-scuer hold the face mask firmly in place. (From Roberts J:
Roberts and Hedges ’ clinical procedures in emergency medicine , ed 6, Philadelphia, 2014, Saunders.)
Fig. 2.26 The rescuer’s fingers are positioned under the angle of the patient ’s mandible to perform a jaw lift. (From Roberts J:
Roberts and Hedges ’ clinical procedures in emergency medicine , ed 6, Philadelphia, 2014, Saunders.)
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CHAPTER 2 Airway Management
and the type of reservoir used (Reardon, et al., 2014a). Delivered tidal volumes vary with bag type, hand size, and patient body characteristics (Rouse & Frakes, 2010).
A BMD that is used without supplemental oxygen will deliver 21% oxygen (ie, room air) to the patient. The BMD should be connected to an oxygen source. To do this, attach one end of a piece of oxygen connecting tubing to the oxygen inlet on the BMD and the other end to an oxygen regulator.
A BMD that is used with supplemental oxygen set at a flow rate of 10 to 15 L/min delivers approximately 40% to 60% oxygen to the patient when a reservoir is not used.
Ideally, an oxygen reservoir should be attached to the bag-mask to deliver a high concentration of oxygen. The reservoir collects a volume of 100% oxygen that is equal to the capacity of the bag.
After squeezing the bag, it reexpands and draws 100% oxygen from the reservoir into the bag.
A BMD that is used with supplemental oxygen set at a flow rate of 10 to 15 L/min and with an attached reservoir delivers approximately 90% to 100% oxygen to the patient. Advantages and disadvantages of BMV are shown in Box 2.8.
Ventilating with a Bag-Mask Device [Objectives 7, 10]
Performing positive pressure ventilation with a BMD can be difficult. Several reasons contribute to this, but none as much as the inability to create a good seal with the mask while simultaneously generating an adequate tidal volume by squeezing the bag. BMV should be a two-rescuer operation. With two people, one is assigned the responsibility of opening and maintaining the airway while creating a good seal with the mask. That frees a second person to squeeze the bag.
To ventilate a patient with a BMD, position yourself at the top of the supine patient ’s head and open the patient ’s airway. If needed, clear the patient ’s airway of secretions or vomitus. If the patient is unresponsive, insert an oral airway. Next, select a bag and mask of appropriate size for the patient.
Connect the bag to the mask if this has not already been done. Connect the bag to oxygen at a flow rate of 15 L/min, and attach a reservoir. Place the mask on the patient ’s face. Create a good face-to-mask seal with the mask positioned over the patient ’s mouth and nose.
Although single-rescuer BMV is not recommended during CPR (Link, et al., 2015), if you find your-self in this situation, press the mask firmly against the patient ’s face with one hand using the E-C clamp technique previously described (and simultaneously use it to maintain the patient ’s proper head position), and then squeeze the bag with the other hand (Fig. 2.28). If a second rescuer is present, the E-C clamp technique or the TE technique can be used.
If an assistant is available, ask him or her to squeeze the bag until the patient ’s chest rises while you press the mask firmly against the patient ’s face with both hands and simultaneously maintain the patient ’s proper head position (see Fig. 2.26). Observe the rise and fall of the patient ’s chest with each ventilation.
Deliver each breath over 1 second and stop ventilation when gentle chest rise is observed. Ventilate the adult patient at a rate of one breath every 5 to 6 seconds, or about 10 to 12 breaths/min.
ACLS Pearl
Assessment of chest rise, breath sounds, oxygen saturation, and capnography should be used to evaluate the effectiveness of oxygenation and ventilation ( Reardon, et al., 2014a).
A reliable indicator of adequate ventilation is the rise and fall of the patient ’s chest wall with each ventilation at an age-appropriate rate. Another indication that the patient is being well ventilated is
BOX 2.8 Bag-Mask Ventilation
Advantages • Provides a means for delivery of an oxygen-enriched mixture to the patient
• Can be used with the spontaneously breathing patient as well as with the nonbreathing patient
• Conveys a sense of compliance of the patient’s lungs to the BMD operator
• Provides a means for immediate ventilatory support Disadvantages • Requires practice to be used effectively
• Delivery of inadequate tidal volumes
• Causes rescuer fatigue
• Can lead to possible gastric distention
an improvement of the patient
an improvement of the patient ’’s condition as evidenced by improvements in color, pulse oximeter read-s condition as evidenced by improvements in color, pulse oximeter read-ings, heart rate, and responsiveness.
ings, heart rate, and responsiveness.
During BMV, avoid excessive ventilation (either by rate or volume) and allow adequate time for During BMV, avoid excessive ventilation (either by rate or volume) and allow adequate time for exh
exhalaalatiotionn toto occoccur.Excesur.Excessiveventisiveventilatlationion decdecreareasesses corcoronaonaryry perperfusfusionion prepressussurere andand maymay decdecreareasese thelike- thelike-lihood for return of spontaneous circulation in patients in cardiopulmonary arrest (
lihood for return of spontaneous circulation in patients in cardiopulmonary arrest ( Aufderheide, et Aufderheide, et al.,al., 2004
2004). Also, feel for compliance when ventilating the patient ). Also, feel for compliance when ventilating the patient ’’s lungs.s lungs. Pulmonary compliance Pulmonary compliance refers to refers to the resistance of the patient
the resistance of the patient ’’s lung tissue to ventilation. The lungs are normally pliable and expand easily.s lung tissue to ventilation. The lungs are normally pliable and expand easily.
If
If thelungsfeelstifforthelungsfeelstiffor infinflexlexiblible,e, lunlungg comcompliaplianceisnceis saisaidd toto bepoor.Uppebepoor.Upperr airairwayobstrwayobstructuction,lowerairwion,lowerairway ay obstruction, severe bronchospasm, and tension pneumothorax are examples of conditions that can cause obstruction, severe bronchospasm, and tension pneumothorax are examples of conditions that can cause poor lung compliance and an inability to ventilate. If at any time you sense poor compliance, reassess the poor lung compliance and an inability to ventilate. If at any time you sense poor compliance, reassess the patient to ensure that the airway remains unobstructed and that lung sounds are clear and equal.
patient to ensure that the airway remains unobstructed and that lung sounds are clear and equal.
Troubleshooting Bag-Mask Ventilation the result of difficulty with providing a leak-proof seal to the face while simultaneously maintaining the result of difficulty with providing a leak-proof seal to the face while simultaneously maintaining an open airway, incomplete bag compression, or both. Gastric inflation may result if excessive force an open airway, incomplete bag compression, or both. Gastric inflation may result if excessive force and volume are used during ventilation.
and volume are used during ventilation.
If the chest does not rise and fall with BMV, reassess the patient in the following manner:
If the chest does not rise and fall with BMV, reassess the patient in the following manner:
•• Begin by reassessing the patient Begin by reassessing the patient ’’s head position. Reposition the airway, and try to ventilates head position. Reposition the airway, and try to ventilate again.
again.
•• Inadequate tidal volume delivery may be the result of an improper mask seal or incomplete bag com-Inadequate tidal volume delivery may be the result of an improper mask seal or incomplete bag com-pression. If air is escaping from under the mask, reposition your fingers and the mask, and reevaluate pression. If air is escaping from under the mask, reposition your fingers and the mask, and reevaluate the effectiveness of bag compression.
the effectiveness of bag compression.
•• Check for an airway obstrCheck for an airway obstruction. Lift the jaw, and suction the airuction. Lift the jaw, and suction the airway as needed. If the chest still doesway as needed. If the chest still does not rise, select an alternative method of positive pressure ventilation.
not rise, select an alternative method of positive pressure ventilation.