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Prehospital Airway Management: A Systematic Review

Key Questions Draft

Open for comment through Dec 20, 2019

Draft Key Questions

Key Question 1

  1. What are the comparative benefits and harms of bag valve mask versus supraglottic airway for patients requiring prehospital ventilatory support or airway protection?
  2. Are benefits and harms modified by:
    1. Techniques or devices used?
    2. Characteristics of emergency medical services personnel (including training, proficiency, experience, etc.)?
    3. Patient characteristics?

Key Question 2

  1. What are the comparative benefits and harms of bag valve mask versus endotracheal intubation for patients requiring prehospital ventilatory support or airway protection?
  2. Are benefits and harms modified by:
    1. Techniques or devices used?
    2. Characteristics of emergency medical services personnel (including training, proficiency, experience, etc.)?
    3. Patient characteristics?

Key Question 3

  1. What are the comparative benefits and harms of supraglottic airway versus endotracheal intubation for patients requiring prehospital ventilatory support or airway protection?
  2. Are benefits and harms modified by:
    1. Techniques or devices used?
    2. Characteristics of emergency medical services personnel (including training, proficiency, experience, etc.)?
    3. Patient characteristics?

Key Question 4

What are the comparative benefits and harms of different techniques for a single airway intervention (bag valve mask, supraglottic airways, or endotracheal intubation) for patients requiring prehospital ventilatory support or airway protection? (Variations may include but are not limited to different technology, devices, drugs, protocols or training.)

Figure 1. Draft Analytic Framework

The analytic framework depicts the relationship between the population, interventions, outcomes, and harms of prehospital airway management using bag valve mask ventilation, supraglottic airway insertion, and endotracheal intubation. The far left of the framework describes the target population as patients requiring prehospital ventilatory support or airway protection. To the right of the population is an arrow that represents prehospital airway management intervention comparisons (key questions KQ1A, KQ2A, KQ3A, and KQ4). An arrow above the airway management comparisons is a diamond that represents contextual factors including techniques and devices, level of EMS personnel, and patient characteristics (KQ1b, KQ2b, and KQ3b). An arrow below key questions represents adverse events or harms of airway management interventions. To the right of the target population is a rectangle with curved edges. This represents intermediate outcomes of the interventions including overall success, first pass success, number of attempts, scene time to secure airway, and effective oxygenation. To the right of this rectangle is a dotted line that leads to another rectangle labeled final health outcomes. These include mortality in prehospital, in hospital, and post hospital settings, morbidity from pneumothorax or aspiration pneumonia, and length of stay in the hospital or ICU. The dotted line illustrates a relationship between the intermediate and final health outcomes. An overarching arrow that extends from the target population represents the direct relationship between the airway interventions and the final health outcomes.

Abbreviations: BVM = bag valve mask; EMS = emergency medical services; ETI = endotracheal intubation; ICU = intensive care unit; KQ = Key Question; SGA = supraglottic airway

Draft Background

Airway management is one of the most important aspects of prehospital care, as it is critical to patient survival and it affects the potential for recovery from emergent illness or injury. The goal of airway management is to assure adequate ventilation and oxygenation. In the prehospital setting, the objective is to secure and protect the airway and then ventilate the patient until the transfer of care to an emergency department (ED) or hospital. Options for airway management range from manual methods to basic interventions to more complex procedures. Manual airway management involves jaw thrust or chin lift, while basic airway management includes the use of oropharyngeal (OPA) or nasopharyngeal (NPA) adjuncts. More advanced airway management techniques include placement of supraglottic airway (SGA) devices, endotracheal intubation (ETI), pharmacologically facilitated intubation (rapid sequence intubation [RSI] or delayed sequence intubation [DSI]), percutaneous airway methods, and surgical airways. The choice of technique and the potential for success depends on the severity of the patient’s injury, the training and skills of emergency medical services (EMS) personnel, setting, and available equipment. More simplistic approaches appear to have lower risks and can be administered by field personnel with less training than is required for ETI. The dilemma is that for a subset of patients, the timely administration of ETI may increase the likelihood of positive outcomes. While ETI is considered the gold standard for airway management, high rates of complications have been reported and prehospital ETI occurs in environments with few resources to mitigate complications.1-5 However, utilization of ETI appears to be increasing, perhaps due to increased involvement of physicians in EMS training, supervision, and planning.6

Issues in prehospital airway management include: (1) correct identification of patients appropriate for prehospital intubation, (2) appropriate use of advanced techniques, (3) who should be certified to perform various prehospital intubation techniques, (4) comparison of the benefit and harms across different airway management approaches (basic and advanced), (5) types of devices to use, (6) the setting for the airway intervention (e.g., on scene or during transport), (7) first pass success rates, and (8) influence of patient characteristics (e.g., cardiac vs. non-cardiac, trauma vs. non-trauma, traumatic brain injury [TBI] vs. non-TBI, and co-morbidities).

EMS agencies are part of larger healthcare systems and are essential components of the healthcare safety net for many communities. Medical direction is now required for all levels of prehospital personnel and many of the most seriously ill or injured patients seen in the ED arrive through EMS. A policy challenge is to clearly define the skill levels for different personnel classifications and estimate the numbers of each required to meet the needs of different communities. Barriers differ across rural versus urban communities, with prehospital care playing a particularly vital role in areas with long transport-to-hospital distances/time7 and underserved areas. Furthermore, direct linkages among prehospital care and inpatient, outpatient, and emergency care are being established and strengthened by technology (e.g., telehealth) and organizational changes. These are transforming prehospital care and contributing to higher quality care as EMS becomes integrated into learning healthcare systems and health information exchange systems.

The purpose of this topic refinement and planned systematic review is to identify the evidence available to support the development of an evidence-based guideline for prehospital airway management. EMS guidelines for respiratory emergencies specify that patients with an inadequate respiratory rate or an inadequate tidal volume require artificial ventilation that is administered through the use of bag valve mask (BVM) or through advanced airway techniques. For the general respiratory emergency patient who is experiencing inadequate respiration, EMS practitioners will continue to artificially ventilate a patient until the transfer of care to a healthcare facility is completed. An evidence-based guideline is needed to establish a uniform and standardized approach to airway management in the prehospital setting.

Based on our prior experience with the prehospital literature and our preliminary searches, we identified broad categories of challenges that will need to be addressed when conducting this review. These challenges are related to identifying inclusion criteria, addressing potential heterogeneity, and the sufficiency of the evidence.

Issues shaping the scope of the planned systematic review include (1) the safety and efficacy of prehospital intubation in the field when an induction agent that involves considerable risk is required; (2) the likelihood that multiple attempts or delay increase the probability of poor outcomes; (3) uncertainty surrounding advanced technology such as video laryngoscopy; (4) difficulties in triage and decision making outside the hospital; and (5) the initial and ongoing training as well as maintenance of skill needs for the different techniques.

Research exists on these topics, but in most cases individual studies are not sufficient to inform policy as they address narrow questions or do not come to definitive conclusions. For example, studies have reported a higher mortality rate when patients were intubated by non-physicians,6 for prehospital intubation compared to emergency department intubation with or without RSI,8 and when intubation is performed by flight non-physicians and all ground EMS providers (physician and non-physician) compared with flight physicians.9 These examples demonstrate that the existing evidence base will both raise and address questions about topics such as appropriate personnel and triage. Planning for a rigorous, systematic assessment of the literature will need to address these issues.

Draft PICOS

Table 1. Draft PICOS

PICOS

Inclusion Criteria

Exclusion Criteria

Populations

Persons with confirmed or suspected respiratory failure requiring ventilatory support or the need for airway protection who are treated in the prehospital setting by Emergency Medical Services clinicians (Paramedic, Advanced Emergency Medical Technician, Emergency Medical Technician, Emergency Medical Responder, etc.).

  • Patients with massive facial trauma where endotracheal intubation or supraglottic airway insertion may be relatively contraindicated.
  • Patients treated with Naloxone to reverse opioid-related respiratory failure.
  • Patients cared for in other than prehospital setting.
Interventions
  • Bag valve mask ventilation
  • Supraglottic airway insertion to include dual-lumen airways
  • Endotracheal intubation
    • Via direct laryngoscopy with or without RSI or DSI
    • Via video laryngoscopy with or without RSI, DSI
  • Patients requiring a surgical airway procedure.
  • Intervention administered by a physician if compared to interventions administered by non physicians.
  • Nasotracheal intubation.
  • Percutaneous devices
  • CPAP and BiPAP
Comparators

KQ1: bag valve mask versus supraglottic airway

KQ2: bag valve mask versus endotracheal intubation

KQ3: supraglottic airway versus endotracheal intubation

KQ4: different techniques for any one of the three included types of airways

  • No airway management
Outcomes Patient Health Outcomes (highest priority)
  • Mortality/survival
    • To arrival at hospital
    • To hospital discharge
    • Any period less than or equal to 60 days post-injury
  • Morbidity
    • Glasgow Outcome Scale, Glasgow Outcome Scale Extended, Modified Rankin Scale, Cerebral Performance Category
    • Pneumothorax
    • Aspiration pneumonia
  • Length of Stay
    • Hospital length of stay (days)
    • ICU length of stay (days)
    • ICU-free days

Intermediate Outcomes (secondary priority)

  • Overall success rate
  • First pass success rate
  • Number of prehospital attempts to secure an airway
  • Scene time to secure airway
  • Effective oxygenation

Adverse Events/Harms

  • Vomiting
  • Gastric content aspiration
  • Hypoxia
  • Hyperventilation
  • Hypotension
  • Oral trauma, airway trauma
  • Barotrauma
  • Mainstem intubation
  • Need for additional airway interventions
Long-term survival (studies that only report for over 60 days or more post injury)
Setting
  • Prehospital
  • ED only to fill important gaps where there are no prehospital studies
Airway studies conducted in cadaver labs, operating rooms, or simulated environments.
Study Design
  • Randomized controlled trials
  • Prospective comparative studies
  • Retrospective comparative studies
  • Case control studies
  • Systematic reviews (we will use reference lists to identify studies for possible inclusion)
  • Case series
  • Descriptive studies
  • Letters to the editor
  • Opinion papers
  • Studies published prior to 1990

Abbreviations: BiPAP = bilevenl positive airway pressure; CPAP = continuous positive airway pressure; DSI = delayed sequence intubation; ED = emergency department; ICU = intensive care unit; KQ = Key Question; RSI = rapid sequence intubation

References

  1. Adnet F, Borron SW, Racine SX, et al. The intubation difficulty scale (IDS): proposal and evaluation of a new score characterizing the complexity of endotracheal intubation. Anesthesiology. 1997 Dec;87(6):1290-7. doi: 10.1097/00000542-199712000-00005. PMID: 9416711.
  2. Caruana E, Duchateau FX, Cornaglia C, et al. Tracheal intubation related complications in the prehospital setting. Emerg Med J. 2015 Nov;32(11):882-7. doi: 10.1136/emermed-2013-203372. PMID: 25604325.
  3. Cook T, Behringer EC, Benger J. Airway management outside the operating room: hazardous and incompletely studied. Curr Opin Anaesthesiol. 2012 Aug;25(4):461-9. doi: 10.1097/ACO.0b013e32835528b1. PMID: 22673785.
  4. Garnier M, Bonnet F. Management of anesthetic emergencies and complications outside the operating room. Curr Opin Anaesthesiol. 2014 Aug;27(4):437-41. doi: 10.1097/ACO.0000000000000088. PMID: 24762955.
  5. Pepe PE, Roppolo LP, Fowler RL. Prehospital endotracheal intubation: elemental or detrimental? Crit Care. 2015 Mar 16;19:121. doi: 10.1186/s13054-015-0808-x. PMID: 25887350.
  6. Crewdson K, Lockey DJ, Roislien J, et al. The success of pre-hospital tracheal intubation by different pre-hospital providers: a systematic literature review and meta-analysis. Crit Care. 2017 Feb 14;21(1):31. doi: 10.1186/s13054-017-1603-7. PMID: 28196506.
  7. Brown JB, Kheng M, Carney NA, et al. Geographical Disparity and Traumatic Brain Injury in America: Rural Areas Suffer Poorer Outcomes. J Neurosci Rural Pract. 2019 Jan-Mar;10(1):10-5. doi: 10.4103/jnrp.jnrp_310_18. PMID: 30765964.
  8. Fevang E, Lockey D, Thompson J, et al. The top five research priorities in physician-provided pre-hospital critical care: a consensus report from a European research collaboration. Scand J Trauma Resusc Emerg Med. 2011 Oct 13;19:57. doi: 10.1186/1757-7241-19-57. PMID: 21996444.
  9. Fouche PF, Stein C, Simpson P, et al. Flight Versus Ground Out-of-hospital Rapid Sequence Intubation Success: a Systematic Review and Meta-analysis. Prehosp Emerg Care. 2018 Sep-Oct;22(5):578-87. doi: 10.1080/10903127.2017.1423139. PMID: 29377753.