Neurocrit Care https://doi.org/10.1007/s12028-019-00812-6 AIRWAY, VENTILATION, AND SEDATION Emergency Neurological Life Support: Airway, Ventilation, and Sedation Asma Moheet1*, Marlina Lovett2, Stephanie Qualls3 and Venkatakrishna Rajajee4* © 2019 Neurocritical Care Society Abstract Neurocritically ill patients often have evolving processes that threaten the airway and adequate ventilation; as such, airway and respiratory management are of utmost importance. Airway management, intubation, ventilation, and sedative choices directly afect brain physiology and perfusion. Emergency Neurological Life Support topics discussed here include acute airway management, indications for intubation with special attention to hemodynamics and preservation of cerebral blood fow, initiation of mechanical ventilation, and the use of sedative agents based on the patient’s neurological status in the setting of acute neurological injury. Keywords: Airway, Ventilation, Sedation, Neurocritical care, Emergency Introduction paralyzing medications should be performed to provide Airway management and respiratory support of the a functional baseline whereby neurological and neurosur- acutely brain-injured patient can be a matter of life or gical decision-making may ensue. death. Failure to establish an airway in a patient with Te Emergency Neurological Life Support (ENLS)- rapidly progressive neurological decline may result in suggested algorithm for the initial management of respiratory arrest, acidosis, secondary brain injury from airway, ventilation, and sedation is shown in Fig. 1. Sug- hypoxemia, elevated intracranial pressure, severe aspira- gested items to complete within the frst hour of evalu- tion pneumonitis, acute respiratory distress syndrome ating a patient are shown in Table 1. Tese suggestions (ARDS), and cardiac arrest. Conversely, the process of are meant to give a broad framework for the principles of induction and intubation itself can result in physiologic diagnosis and emergent management of airway, ventila- changes which increase intracranial pressure (ICP) in tion, and sedation, which can be adapted to refect global brain-injured patients, worsen cerebral perfusion in and regional variations based on the local availability of patients with an ischemic penumbra, and result in loss diagnostic tools and treatments. of the neurological examination at a time when it is required for urgent decision-making. Assessing the Need for Intubation Te goals of airway management in neurological Patients in severe respiratory distress or impending res- patients are to maintain adequate oxygenation and ven- piratory or cardiac arrest should be intubated without tilation, optimize cerebral physiology, preserve cerebral delay. Additionally, a patient who cannot “protect their perfusion, and prevent aspiration. A rapid neurological airway” because of progressive neurological decline or assessment prior to the administration of sedating and concern for aspiration may need tracheal intubation. Intubation should not be delayed, but due to the potential *Correspondence: [email protected]; [email protected] for complications such as signifcant hemodynamic dis- 1 Neurocritical Care, OhioHealth - Riverside Methodist Hospital, turbances, a rapid but thorough risk–beneft assessment Columbus, OH, USA should be conducted. Te decision to intubate is infu- 4 Departments of Neurosurgery and Neurology, University of Michigan, Ann Arbor, MI, USA enced by factors specifc to patient physiology, clinical Full list of author information is available at the end of the article environment, and the anticipated course of care. Fig. 1 ENLS airway, ventilation, and sedation protocol A stuporous, deteriorating, or comatose patient requir- With these considerations in mind, there are four com- ing extended transport, transfer, imaging, or invasive monly accepted indications to intubate: procedures may be most appropriately managed with a secure endotracheal airway. Table 1 Airway, ventilation, and sedation checklist within the frst hour Checklist □ Assess the need for intubation or noninvasive positive pressure ventilation □ Perform and document a focused neurological assessment prior to intubation □ Verify the endotracheal tube position □ Determine ventilation and oxygenation targets, and verify with ABG/SpO2/ETCO2 □ Assess the need for analgesia and/or sedation in mechanically ventilated patients ABG arterial blood gas, ETCO2 end-tidal CO2, SpO2 peripheral oxygen saturation 1. Failure to oxygenate is indicated. When spontaneous breathing is absent or seriously impaired, bag mask ventilation (BMV) should Tis fnding may be determined by visual inspection be performed. Airway adjuvants such as a nasal airway or such as evidence of respiratory distress or cyanosis, vital oropharyngeal airway may be used. Te decision to per- signs data such as low oxygen saturation on pulse oxime- form endotracheal intubation in the prehospital setting, try, or laboratory data such as arterial blood gas analysis. however, can be challenging. Prehospital intubation has been best studied in severe traumatic brain injury (TBI). 2. Failure to ventilate Observational studies in the setting of TBI have been inconsistent [5], with some studies demonstrating pos- Ventilation is assessed by visual inspection including sible harm from prehospital intubation [6]. In one study, observation of respiratory efort exerted, capnometry prehospital intubation performed by aeromedical crews through nasal cannula or transcutaneous monitoring [1], with specialized training was associated with improved and/or arterial blood gas analysis. outcomes [7]. An Australian randomized clinical trial of patients with TBI with Glasgow Coma Scale (GCS) ≤ 9 3. Failure to protect the airway and > 10 min of ground transport time to a designated trauma center demonstrated improved 6-month out- Airway protection is the result of numerous variables comes in patients who underwent prehospital intubation including bulbar function, airway anatomy, quantity and [8]. Given these conficting results, and extrapolating quality of secretions, strength of cough refex, and ability to from studies performed in TBI, prehospital intubation swallow after suctioning [2, 3]. Te presence of a gag refex in patients with acute neurological injury should be per- is an inadequate method of assessing airway protection [4]. formed by personnel with appropriate training and expe- rience in Rapid Sequence Intubation (RSI) patients with 4. Anticipated neurological or cardiopulmonary decline GCS < 9, an inability to protect the airway or hypoxemia requiring transport or immediate treatment despite the use of supplemental oxygen. When person- nel with appropriate training and experience are not pre- Anticipation of the trajectory of the patient’s condition sent, or an attempted intubation is unsuccessful, BMV can allow for appropriate preparation for the procedure should be performed in conjunction with basic airway- as opposed to rushed or emergent intubations. opening maneuvers or airway adjuncts while the patient is transported to the hospital. Of note, supraglottic airway (SGA) devices may be especially useful under these cir- Prehospital Management cumstances, as an alternative to endotracheal intubation First responders assessing patients with impaired breath- in the prehospital setting, or by persons trained in these ing in the setting of possible underlying neurological devices, but not intubation. Once an endotracheal tube or injury should rapidly assess the scene and provide support SGA has been placed, the use of quantitative capnography for airway and breathing in a safe and expeditious man- should be used when available, to avoid both hypoventila- ner. Patients who sufer acute neurological injury may tion and hyperventilation [1]. demonstrate one of the above criteria for intubation at the time of assessment. Tose with an inability to protect the airway should be managed immediately with an airway- Decision Made to Intubate: Perform Neurological opening maneuver: the jaw-thrust maneuver is preferred Assessment when the cause of the patient’s neurological impairment When circumstances permit, urgent management of is not readily apparent and cervical spine immobilization the airway should coincide with a focused neurological assessment. Te examination can typically be conducted L = Look externally, for features such as abnormal in 3 min or less, as many components of the examination facies, oro-maxillo-facial trauma, and abnormal body rely simply on careful observation of the patient while habitus they are being stabilized. Te pre-sedation/pre-intuba- E = Evaluate with the 3-3-2 rule: tion neurological examination establishes a baseline that is used to assess therapeutic interventions (e.g., patients • Will 3 of the patient’s fngers ft between the inci- with stroke, seizures, hydrocephalus, or other disorders) sors of the open mouth? If not, mouth opening may or may identify injuries that are at risk of progressing be too limited to permit adequate DL or manipula- (e.g., unstable cervical spine fractures). Te assessment tion of the endotracheal tube. identifes the type of testing required and may help to • Will 3 of the patient’s fngers ft between the chin limit unnecessary interventions, such as radiological cer- (mentum) and the hyoid bone? If not, the airway vical spine clearance. Findings should be documented may be too anterior for easy visualization with DL. and communicated directly to the team that assumes care • Will 2 of the patient’s