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For the majority of AMS patients, the first priority is to establish and maintain an adequate airway. A patient who is unresponsive may not be able to protect his or her airway, and an obstructed airway may be contributing to altered mental status. Evaluate whether the patient can protect his or her airway; whether there is a need for suction, or repositioning, or removal of a physical obstruction; and whether airway adjuncts or advanced airway placement is necessary. A nasopharyngeal or oropharyngeal airway, if tolerated, may be a helpful adjunct to maintain airway patency. If no contraindication exists (particularly the need for spinal precautions), the lateral decubitus position may be advantageous for airway protection in many AMS patients (see Chapters 2, 3, and 4).

Once the airway is patent, assess breathing adequacy. If the patient is apneic or hypoventilating, respirations should be immediately assisted using a bag‐valve mask. Advanced airway placement for longer‐term ventilation may be considered if bag‐valve‐mask ventilation is not effective, but the majority of patients can be initially managed with airway adjuncts, enough hands, and basic maneuvers.

Hypoxia may also be a cause or an effect of altered mental status. Assessment of respiratory rate and depth, as well as pulse oximetry, can assist the EMS clinician in determining if there is a need to improve the patient’s oxygenation. Supplemental oxygen via nonrebreather mask may be the most appropriate initial therapy for a hypoxic patient with adequate respiratory drive and tidal volume while other vital signs are being assessed, but positive‐pressure ventilation with supplemental oxygen may be required for the hypoxic patient with shallow or otherwise ineffective respiratory effort.

Noninvasive positive‐pressure ventilation (NIPPV, e.g., CPAP or BiPAP) may be of special assistance in the patient who is hypercapneic and/or hypoxic as a cause of AMS. NIPPV may improve ventilation, gas exchange, and CO₂ removal, and therefore treat AMS. However, choice of this therapy is predicated upon the patient being able to protect his or her airway, have an adequate respiratory drive, and have a mental status capable of tolerating the mask and clinician instructions. Attempting NIPPV in a patient with AMS mandates meticulous ongoing attention to the patient to evaluate for improvement or decline in mental status and vital signs. As an additional assessment parameter, waveform end‐tidal CO₂ monitoring can assist the EMS clinician in both diagnosing and managing the patient with elevated pCO₂. Should the patient decline while being treated with NIPPV, or mental status worsen such that the patient cannot cooperate with the therapy or protect his or her airway, manual supportive airway measures such as a bag‐valve‐mask with advanced airway placement will be required to facilitate positive‐pressure ventilation.