Laryngeal tube insertion in out of hospital cardiac arrest may save lives

Henry E.Wang, Robert H. Schmicker,  Mohamud R. Daya et el  published PART trial (Pragmatic Airway Resuscitation
Trial) in which they compared laryngeal tube insertion with endotracheal intubation in out of hospital cardiac arrest. 

BACKGROUND

About 350000 adults in the United States suffer out of hospital cardiac arrest each year, with less than 10%surviving to hospital discharge.  More than 30 years ago, Endotracheal intubation became a standard US paramedic practice under the assumption that it would improve OHCA outcomes. However, many studies have highlighted the challenges of paramedic Endotracheal intubation , including significant rates of unrecognized tube misplacement
or dislodgement, need for multiple attempts, and insertion failure. Endotracheal intubation been associated
with iatrogenic hyperventilation and chest compression interruptions. Last but not least, paramedics may only perform 1 live intubation per year. 

Supraglottic airway (SGA) devices include the laryngeal mask airway, esophageal-tracheal combitube, i-gel, and laryngeal tube (LT). Compared with endotracheal intubation, SGA insertion is rapid, simple, and requires less training.

PATIENTS

Adults 18 yrs or older with non traumatic out of hospital cardiac arrest. Total of 3004 patients.

Following were excluded– pregnancy, prisoners, ET tube before EMS arrival, tracheostomy presence, DNR orders.

TRIAL

Multicenter pragmatic cluster-crossover clinical trial,  funded by a National Heart, Lung, and Blood
Institute (NHLBI) involving  31 EMS agencies from following states- Alabama, Texas, Wisconsin, Pennsylvania,  Oregon and Washington. 

OUTCOMES

Primary outcome was survival to 72 hours. 

Secondary trial outcomes included (1) ROSC(presence of palpable pulses on emergency department arrival), (2) survival to hospital discharge, and (3) favorable neurological status on hospital discharge (Modified Rankin Scale score ≤3). Other secondary outcomes included EMS airway management course and hospital adverse events.

RESULTS

Primary outcome-

72-hour survival was 18.3% in the Laryngeal tube group vs 15.4% in the Endotracheal intubation group. ( difference was 2.9% (95% CI, 0.2%-5.6%; P = .04; relative risk, 1.19 [95% CI, 1.01-1.39])

Secondary outcomes-

Laryngeal tube vs Endotracheal intubation

  1. Return of spontaneous circulation (27.9% vs 24.3%; adjusted difference, 3.6% [95% CI, 0.3%-6.8%]; P = .03)
  2. Hospital survival (10.8% vs 8.1%; adjusted difference, 2.7% [95% CI, 0.6%-4.8%; P = .01)
  3. Favorable neurological status at discharge (7.1% vs 5.0%; adjusted difference, 2.1% [95% CI, 0.3%-3.8%] P = .02). 

BASELINE CHARACTERISTICS DIFFERENCES

Following differences were observed between two groups

  1. Elapsed time from first EMS arrival to airway start was shorter for LT than ETI (median, 9.8 vs 12.5 minutes).
  2. Initial LT and ETI success rates (excluding BVM) were 90.3% and 51.6%.
  3. Clinicians at receiving emergency departments converted 64.4% of EMS LT to ETI.
  4. Among patients receiving successful EMS ETI, emergency department clinicians performed repeat ETI in 33.1%.
  5. A total of 352 patients received BVM only without any advanced airway insertion efforts.

LIMITATIONS OF STUDY

  1. In Pragmatic trials , Power is decreased and a larger sample size is needed compared with an individual randomized trial.
  2. Trial could not assess the influence of chest compression or ventilation quality.
  3. Trial focused on LT use and not other SGAs

ANOTHER TRIAL

Jonathan R. Benger, Kim Kirby, Sarah Black et el published another trial(The AIRWAYS-2 )in JAMA comparing  supraglottic airway device compared with endotracheal intubation in out of hospital cardiac arrest. 
In this pragmatic cluster randomized trial (N = 9296) conducted in the United Kingdom,  airway management strategy using a different type of supraglottic airway was compared with endotracheal intubation.
In this trial,  authors found no significant difference in the primary outcome of a favorable neurological outcome at
30 days (defined as a modified Rankin Scale score ≤3), which occurred in 6.4% of patients in the supraglottic airway group and 6.8% in the endotracheal intubation group (absolute risk difference, -0.6% [95% CI, -1.6% to 0.4%]).
Rates of endotracheal intubation or reintubation at hospital admission were not reported in the trial .
the initial endotracheal intubation success rate was 69% ( compared with a 91% success rate
for paramedics reported in a previous meta-analysis
).
DIFFERENT COUNTRY DIFFERENT OUTCOMES
Interesting part about the trial reported in the United Kingdom by Benger et el Is that they screened about 13,000 patients with cardiac arrest, Out of which about 6500 were not resuscitated.  Out of which about 2000 patient’s were excluded, Which has some interesting exclusion criteria such as mouth only opens less than 2 cm.
In the trial reported from United States by Wang et el, Each arm had about 1950 patients but only 460 patients were excluded.
72-hour survival was similar in the 2 groups, But there was higher initial ventilation success rate in supraglottic airway group(87.4% and supraglottic airway device versus 79% endotracheal intubation P value less than 0.01)
BOTTOM LINE
Endotracheal intubation is a skill that needs practice to acquire and maintain.  For most EMS personnel,  out-of-hospital Cardiac arrest is encountered with relatively infrequently, limiting their exposure to patients with cardiac arrest as well as patient requiring intervention such as advanced airway management.
These 2 trials raise the question of whether endotracheal intubation should be the preferred choice of airway management and out of hospital cardiac arrest.
Whether an even simpler technique such as bag valve mask ventilation or supraglottic airway, should be used and out of hospital cardiac arrest by EMS personnel.