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Prehospital Airway Management: To Intubate or Not to Intubate David Lobel MD FACEP, Medical Director, Ambulance Department, Maimonides Medical Center Endotracheal intubation
has been in use by paramedics for nearly two and a half decades,
yet as medicine in general and emergency medicine in specific have
become progressively more evidence based, this practice has been
the subject of scrutiny and debate. The 2005 American Heart Association
Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular
Care specifically recommends bag-valve mask ventilation for infants
and children, stating that it as effective as endotracheal intubation
for short periods of time, and may be safer.1 As emergency physicians,
whether we serve as EMS medical directors or not, we share responsibility
of providing oversight and quality assurance for prehospital care.
The following is a critical review of the evidence to date and a
discussion of the future of endotracheal intubation in the prehospital
setting. Success of endotracheal
intubation by paramedics has been studied extensively.2-5,7-16 Rates
of successful intubation by paramedics in the field have been reported
as high as 98.4%, but are more commonly in the 80-90% range. Wang
and colleagues looking prospectively at 783 patients with attempted
intubation across advanced life support services in urban, suburban,
rural and air medical settings report an overall success rate of
86.8%. The success rate for cardiac arrest victims was reported
at 92.8% and dropped to 76.8% in non-arrest patients. Ninety-eight
percent is a laudable success rate in many accomplishments, but
when that translates to almost two of every 100 patients not having
a definitive airway, we must consider if that even approaches an
adequate success rate. In the study of 2,614 prehospital intubations
in which Bulger et al.2 cited that 98.4% success rate, 12 patients
received paralytics without achieving airway access. Drs. Wang and Yealy13
analyzed the data more closely, looking not only at success rate,
but at success rate by number of attempts. In a prospective study
of 42 EMS agencies over an 18-month period, complete data were available
for 1,941 cases. The cumulative overall success rate was 91.8% after
three attempts with nearly 30% of patients requiring more than one
attempt at ETI. The authors noted slightly higher success rates
with patients in cardiac arrest, but also noted slightly lower success
rates in patients who received RSI, and significantly lower success
rates (77% cumulative) in patients in whom sedation facilitated
intubation was performed. The article notes that multiple attempts
at ETI are associated with complications that include hypoxemia,
airway trauma, bradycardia and cardiac arrest. Furthermore, field
intubation may increase the time on scene, delaying care for underlying
injury or illness.14 Dunford et al.,8 looked
specifically at the complications of “rapid sequence intubation.”
Using continuous recordings of oxygen saturation and heart rate
during prehospital ETI with RSI, they observed that 57% of patients
experienced desaturation. Desaturation was defined as oxygen saturation
less than 90% in patients whose baseline had been above 90% or a
decline from baseline if the initial saturation with basic life
support interventions had been less than 90%. The median time of
desaturation was 160 seconds, with a median decrease in oxygen saturation
of 22%. Significant alterations in pulse rate were also noted in
the study group. While 61% of patients experienced a drop in pulse
of 20 bpm or more, 19% experienced profound bradycardia, defined
as a heart rate less than 50 bpm. An additional 29% of these patients
experienced an increase in pulse of 20 bpm or more. In the vast
majority of patients who experienced desaturation (84%) paramedics
described the intubation as “easy.” One of the most significant
areas to receive attention in this area is outcomes data. In a controlled
clinical trial that compared survival and neurological outcome in
children requiring airway management, Gausch et al.4 found no statistically
significant difference overall in survival and neurological outcome
between the group treated with ETI versus those managed with bag-valve
mask ventilation (analysis based on intent to treat). In a subgroup
analysis the authors noted significant worsening in survival or
neurological outcome in patients with a final diagnosis of respiratory
arrest, child maltreatment, or foreign body aspiration when treated
with ETI. A similar outcomes analysis looked at the use of rapid
sequence intubation in severe traumatic brain injury.5 Davis et
al. looked at 209 patients with severe head injury and matched each
patient with three controls with similar injury severity from the
trauma registry. The authors found that mortality was significantly
increased in the trial cohort, and incidence of good outcomes decreased.
The authors attributed these findings to transient hypoxia, inadvertent
hyperventilation, and longer on-scene times among other factors. In many EMS systems, paramedics
have little experience with intubation,15 at the same time it is
recommended that regular experience with ETI along with rigorous
training and close monitoring of a limited number of providers are
the cornerstones of a successful program.16 The Bulger study2 out
of Seattle which reports the single highest success rate for prehospital
intubation, specifically state that their paramedics have over 3,000
hours of advanced medical training, with ongoing operating room
access, quarterly training sessions, and animal labs which are repeated
every two years. The EMS in that study also has a minimum requirement
of 12 intubations annually by each medic to maintain credentialing.
This level of training and oversight is neither possible nor practical
in all settings. In implementing an EMS
system that includes prehospital ETI protocols the medical director
must weigh what conditions warrant advanced airway management (possibly
burns and drowning) and which conditions are better served by rapid
transit with non-invasive ventilatory techniques (e.g. head injury,
trauma). Protocols that specify that endotracheal intubation should
only be employed if less invasive techniques are not effective,
encourage the use of non-invasive ventilation, without taking ETI
out of the hands of paramedics. The use of alternative or rescue
devices such as laryngeal mask airway or esophageal obturator devices
should be considered in services that use ETI, especially in the
setting of sedative facilitated or RSI aided intubation. Training
in airway techniques with practice sessions either in the operating
room or with simulators should be offered to help paramedics maintain
a satisfactory skill level. The available evidence might seem to point toward removing ETI from the paramedic scope of practice, but the issue is more complex than that. Rather than striking ETI from the paramedic armamentarium, selective use of paramedic ETI should be based on very specific protocols and parameters. Taking a life saving intervention out of the hands of paramedics would be reprehensible. As emergency physicians we need to continue to provide evidence based direction with regard to what circumstances ETI should and should not be used. The fact that there is significant evidence to suggest that paramedics with better training and oversight are better at airway management should serve as a call to all emergency physicians to participate in the training and oversight of prehospital providers. References:
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