Artificial airway

Facial and neck injuries may predispose the victim to airway and ventilatory difficulty. Airway compromise may result if the patient with facial fractures remains in a supine position due to lack of bony support. Progressive airway obstruction may also result from hemorrhage from penetrating neck wounds. Bleeding into the trachea, bronchus, and lungs will all compromise the victim s airway and ventilatory status. An artificial airway should be placed to maintain airway patency until intubation is required (American College of Sur-... 

For inhalation exposure, the patient should be removed from fumes into fresh air. Respirations should be established along with the creation of an artificial airway if necessary. If cough or difficulty in breathing develops and is not relieved by the fresh air, the patient should be evaluated for respiratory irritation, bronchitis, or pneumonitis in a health care facility. 

The airway can also be maintained with artificial oropharyngeal or nasopharyngeal airway devices. These are placed in the mouth or nose to lift the tongue and push it fonward. They are only temporary measures. A patient who can tolerate an artificial airway without complaint probably needs an endotracheal tube. 

During any type of anesthesia care, an EGG monitor, pulse oximetry, non-/ invasive blood pressure measurement and a reliable peripheral i.v. access are standard. If airway tools are employed, capnography is standard of care to prove correct placement of the artificial airway and the presence of respiration, gas exchange and circulation [18]. 

The patient-ventilator interface includes the ventilator circuitry and the artificial airway. The most important complications are ventilator disconnections, reported in 8-13% of ventilated patients (56,57). Because circuit pressure and flow can still occur with the ventilator disconnected from the patient it is critical that carefiilly set alarms are present (3). Other complications include obstruction from secretions, circuit leaks, airway injury from inadequate heat or humidity, tracheal injury from the artificial airway, and loss of delivered VT in a compliant circuit. 

Regardless of whether a ventilator uses positive pressure or negative pressure, the trans-pulmonary pressure gradient determines the tidal volume. A ventilator that is a pressure controller delivers a preset pressure and this variable is unaffected by changes in limg compliance or resistance. A positive pressure ventilator applies pressure inside the chest to expand it using a noninvasive interface, or an artificial airway. 

Some studies suggest that liberation from mechanical ventilation is a requirement for decannulation (6), but this precludes the provision of noninvasive ventilation (NIV) as part of decannulation and may be impossible for some patients who could otherwise be dec-annulated. Other reports recognize that decannulation may proceed to NIV 24 hours a day without the requirement of an artificial airway (7) provided bulbar function is adequate and airway clearance is achieved (8). 

There is an important distinction between dependence on an artificial airway and mechanical ventilation, which can be provided noninvasively (9). The requirement for an artificial airway may reflect bulbar impairment as, in those with adequate bulbar function, noninvasive ventilation will sustain adequate ventilation even with veiy limited respiratory muscle function. Therefore, tracheostomized patients with preserved bulbar control can undergo decannulation. Airway secretions are important determinants of dependence on mechanical ventilation through an artificial airway, and aspiration pneumonia may result from an impaired level of consciousness, poor bulbar function, or inability to cough effectively. Such issues must be addressed by airway clearance techniques, prior to decannulation. 

The term weaning encompasses two different stages with specific requirements (i) discontinuation of invasive ventilation and (//) removal of the artificial airway (Fig. 1). The first step is to assess the potential to discontinue invasive ventilation either to autonomous breathing or to NTV support. If the patient fulfills the necessary criteria, a formal spontaneous breathing test (SET) is performed. If successful, the patient can then be disconnected from the ventilator, or in case of a failed SET transitioned to NIV. The next step includes removal of the artificial airway, provided secretion management or upper airway obstruction is not an issue. 

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