Page 102 - JSOM Fall 2020

Heffner et al. found that 22% of normotensive patients ex- ITP. Contrary to the impact of PPV on lowering EDV, SV, CO,
perience hypotension after emergency intubation in the ED, and DO , multiple human experiments have demonstrated the
2
suggesting that an elevated ITP caused by PPV alone may be effect of enhancing cardiac filling, CO, and tissue perfusion
sufficient to reduce CO in normotensive patients. 22 by reducing ITP, increasing tolerance to experimentally pro-
29
gressive reductions in central blood volume similar to hemor-
Kim et al. found that systolic hypotension prior to intubation, rhage, and promoting higher perfusion (arterial) pressures in
30
defined as a systolic blood pressure ≤90mmHg, was inde- patients with various etiologies of hypotension and hemor-
31
pendently associated with postintubation cardiac arrest (odds rhage. These consistent observations that link lower ITP with
32
ratio [OR] 3.67, 95% CI: 1.58–8.55; P = .01). 23 enhanced hemodynamic responses opposite to those induced
by PPV also provide inferential evidence to avoid the use of
In a retrospective analysis of trauma patients, Chou et al. found intubation in hypovolemic patients when possible.
that field intubation may be associated with higher mortality
in trauma patients with hemorrhagic shock requiring mas- Experience
sive transfusion. Less invasive airway interventions and rapid
transport might improve outcomes for these patients. 24 The experience of every clinician may vary, but there are many
well-known risks of RSI and PPV besides the reductions in CO.
Fevang et al., in a systematic review and meta-analysis com-
paring mortality in prehospital tracheal intubation to ED in- • After RSI, the potential Can’t Intubate Can’t Oxygenate
tubation in trauma patients, found the median mortality rate (CICO) situation
in patients undergoing prehospital intubation was 48% (range • Unrecognized esophageal intubation
8–94%), compared with 29% (range 6–67%) in patients • Loss of situational awareness
undergoing intubation in the ED. The authors stated that • Complex decision-making, thereby increasing cognitive
“Cardiovascular collapse is a known complication of TI in load and loss of bandwidth
this patient group, and some centres deliberately postpone in- • Fixation error during the process of RSI Intubation.
hospital TI in patients in shock until after initial stabilization.” 25 • Prolonged on scene time, and thus time to surgical con-
trol of bleeding, which is known to be an important fac-
In a retrospective database review, Crewdson et al. found tor in patient survival 27
that their “results suggest an association between prehospital • Resource intensive both in equipment and personnel
emergency anesthesia and in-hospital mortality in awake hy- • In the prehospital or RDCR environment, if a difficult
potensive trauma patients, which is strengthened when hypo- or failed intubation is encountered, there is often no re-
tension is due to hypovolemia.” Based on these findings, the course to specialist assistance.
authors suggested that delayed induction of anesthesia may be • Hyperventilation both in the preoxygenation phase be-
appropriate. 26 fore RSI and postintubation has the effect of further de-
creasing venous return.
Schwaiger et al. demonstrated that postponing intubation in • In the patient with penetrating injury or poly trauma,
spontaneously breathing major trauma patients on ED ad- the move to PPV raises the incidence of tension pneu-
mission does not impair outcome in a retrospective analysis. mothorax, which in turn necessitates further advanced
Although a relatively small sample size was analyzed, these procedures like thoracostomies.
results demonstrated the feasibility of delaying intubation. 27 • Hypoxia is a well-documented complication of RSI both
from lack of preoxygenation and prolonged, or succes-
Taghavi et al. investigated “permissive hypoventilation” in a sive, attempts to pass the tube. 33
swine model of hemorrhagic shock. The authors concluded • Prehospital anesthesia is associated with hypothermia,
28
that retaining spontaneous ventilation “results in less hemody- which has been shown to have a negative impact on out-
namic suppression and better perfusion of vital organs.” They comes in trauma patients. 34
recommended that “In severely injured penetrating trauma • RSI and PPV contribute to the lethal triad of acidosis
patients, consideration should be given to immediate trans- and coagulopathy, by lowered DO and hypothermia by
2
portation without PPV.” anesthesia.
The perspective to limit RSI and PPV in clinical states of severe The net outcome of the effects described here has led to the
blood loss or hemorrhagic shock until intravascular volume often-described sequence of events of RSI – PPV – CPR.
is restored with blood products is particularly important to
military medical operations. A preliminary analysis generated Knowledge
from the US Department of Defense Trauma Registry indicates
that 59% of the 8,653 combat casualties from 2002 to 2019 Any practitioner should have knowledge of the indications,
who were intubated also suffered from hemorrhage, indicated contraindications, complications, managing or preventing the
by receiving at least 1 unit of WB. This means that a signifi- complications, recognizing a successful intervention, and rec-
cant proportion of injured who receive airway management ognizing the physiological impact of the intervention, whether
may be at increased risk of suffering from detrimental effects positive or negative, before commencing with RSI and or PPV.
such as iatrogenic harm induced by RSI and PPV.
Indications
Another approach to the examination of evidence against the The primary need for advanced airway management remains
use of PPV in patients with severe blood loss or hemorrhagic the failure of basic procedures, especially patient positioning.
shock is to extract data from the literature that alter the para- It is also recognized that RSI and PPV are required for dam-
digm of PPV by examining the effect of creating more negative age control surgery. Other indications include severe facial

100 | JSOM Volume 20, Edition 3 / Fall 2020