Does Pre-hospital Endotracheal Intubation Improve Survival in Adults With Non-traumatic Out-of-Hospital Cardiac Arrest?

A Systematic Review

Ling Tiah, MBBS, MPH; Kentaro Kajino, MD, PhD; Omer Alsakaf, MD; Dianne Carrol Tan Bautista, PhD; Marcus Eng Hock Ong, MBBS, MPH; Desiree Lie, MD, MS.ED; Ghulam Yasin Naroo, MBBS; Nausheen Edwin Doctor, MBBS; Michael YC Chia, MBBS; Han Nee Gan, MBBS


Western J Emerg Med. 2014;15(7):749-757. 

In This Article


Search Strategy

Three authors (KK, OA, TL) conducted a search of the MEDLINE, Scopus and CINAHL databases for eligible studies published in English between January 1, 1980, and April 30, 2013. The search strategy used relevant keywords as Medical Subject Headings terms in MEDLINE; and free-text words in the other two databases in the following combinations: (intubation or endotracheal or intratracheal or supraglottic or laryngeal mask or combitube or esophageal tracheal or esophageal tracheal) and [(out-of-hospital or pre-hospital) and (cardiac arrest or heart arrest)] and (emergency medical services or paramedic). Filters were applied to include only human studies and to exclude studies involving only children.

For the purpose of this review, we defined ETI as the placement of a secured cuffed tube in the trachea. SGA in this review refer to devices currently in use by most EMS systems, such as the laryngeal mask airway, the laryngeal tube and the esophageal-tracheal Combitube.[13,28,29] We excluded use of now- obsolete, earlier generation devices.[26]

Study Eligibility Criteria and Data Extraction

We included randomized controlled trials and cohort studies with patient outcomes comparing the use of ETI and SGA in pre-hospital settings. We excluded studies that provided a comparison of either ETI with bag-valve-mask ventilation only or SGA with bag-valve-mask ventilation only. We also excluded reviews of studies, editorials and other papers without patient data.

We restricted our review to studies that involved adults 18 years or older with non-traumatic OHCA. We excluded studies with undifferentiated study populations of adults and pediatric patients (younger than 18 years) and those with undifferentiated causes of OHCA. EMS personnel involved in the advanced airway management could be physicians, nurses, paramedics, emergency medical technicians or basic-level emergency medical technicians. Studies that involved military medical and evacuation services were excluded.

Studies had to provide at least one of the following patient-based outcomes: (1) return of spontaneous circulation (ROSC), defined as the presence of a palpable pulse without cardiopulmonary resuscitation, which could be specified to be before or upon arrival in the emergency department or unspecified; (2) survival to hospital admission to an inpatient ward; (3) survival to hospital discharge, regardless of the length of hospital stay; and (4) favorable neurological or functional outcome with the use of validated measures, such as the Cerebral Performance Category Score, the Modified Rankin Scale or the Health Utilities Index.[30–32] We excluded studies that reported only non-patient-centered outcome measures relating to personnel ease of use, device complications or effectiveness of ventilation in terms of biochemical or physiological markers.

Three authors (KK, OA, TL) screened titles and abstracts of studies generated from the search (KK, OA, TL). Full text articles were next obtained for studies eligible for inclusion. Only studies meeting the inclusion and exclusion criteria were then selected for final quality review.

Two reviewers (GHN, TL) then independently reviewed the included studies for assessment of methodological quality. None of the included studies were randomized trials, so we chose the Newcastle-Ottawa Scale (NOS) for rating study quality.[33,34] The NOS assigns a minimum of zero and a maximum of four stars for three criteria (patient selection, comparability and outcome) based on a total of eight questions. The stars were then tallied to provide four categories of study quality (poor = 0 to 3 stars; fair = 4 to 5 stars; good = 6 to 7 stars and excellent = 8 to 9 stars).

We extracted information about study design, participants, sample size, airway modalities investigated (ETI versus SGA), patient outcome measures, key findings and authors' conclusions or recommendations and collated it into a descriptive summary table. The results were not pooled into a meta-analysis because of variation across EMS systems among the included studies. Instead, two authors (DB, TL) extracted data pertaining to the effect size of respective outcome measures from each study (where provided or available). If the adjusted analysis was not available, we calculated the unadjusted odds ratios (OR) with 95% CI based on number of events in respective outcome measures for ETI versus SGA (if reported).