Video laryngoscopes help improve the view of the epiglottis during endotracheal intubation.
80%. Your partner places an oropharyngeal airway
(OPA) device, which allows ventilation with continued high fraction of inspired oxygen (FIO2) rate via
the BVM. Maintaining a rate of eight to 10 to avoid
hyperventilation, you see the SpO2 climb to 95%
over the next three minutes. Addition of a disposable
positive end-expiratory pressure (PEEP) valve to the
exhalation port of the BVM results in improvement
of the SpO2 to 100%.
Just prior to becoming apneic, his SpO2
was the brink of the steep portion of the
hemoglobin desaturation curve (see Figure
1, p. 35). Further desaturation, even if brief,
indicates a precipitous fall in arterial oxy-
gen content and will place the brain and
other vital organs at risk for anoxic damage.
A further rise in CO2 diminishes the affin-
ity of hemoglobin for oxygen further wors-
ening oxygen delivery to organs. Note that
there’s a lag time between the SpO2 regis-
tered by the pulse oximeter and the real-time
arterial saturation. This delay can range from
a few to 30 seconds depending on the etiol-
ogy (e.g., heart failure vs. septic shock) and
severity of illness. Unfamiliarity with this
characteristic of the pulse oximeter may
cause mistaken concern that the patient isn’t
improving with BVM therapy. Conversely,
false confidence may result when the patient
is “desaturating,” yet the pulse oximeter con-
tinues to read 100%.
PHO TO IOSEPH/ISTOCKPHO TO. COM; PHO TOS AR T VANDALAY
100% saturated who are paralyzed prior to
elective intubation. This is a “best case” scenario, and the times to desaturation should
not be generalized to EMS patients. However, one does see how rapidly ill or pediatric apneic patients will become hypoxemic.
For types of patients made apneic by RSI,
see Figure 1.
BVM VENTILATION & OXYGENATION
EMS providers are overconfident in their
skills and knowledge in how to use BVMs.
Multiple studies of prehospital resuscitations
have documented compression rates that
are too rapid, inspiratory pressures generated by bag compression that’s too great and
volumes of air per compression that are too
large for optimal outcomes. These factors
strongly predict patient harm in the patients
with severe obstructive lung disease, such
as COPD or asthma. Rapid large-volume