ITU TeachingFriday 5th April 2013

Association of Prehospital Advanced Airway Management With Neurologic Outcome and Survival in Patients With Out-of-Hospital Cardiac Arrest-Hasegawa, Hirade, Chang & Brown

-JAMA 2013; 309(3):257-266

Background• Rate of survival after OHCA has improved but is

still low• Associated with better early access to medical

care, early CPR, rapid defibrillation, and better post-arrest care

• Advanced airway management (ETT or supraglottic airway) considered to be gold-standard in management of OHCA

• No large-scale studies on association between type of airway management and outcomes such as neurological status after OHCA

Purpose of Study

“to examine whether CPR with any type of out-of-hospital advanced airway management by EMS personnel, compared with CPR with conventional bag-valve-mask ventilation, would be associated with favourable neurological outcome in adult OHCA"

Method 1

• In Japan EMS personnel have been able to use supraglottic airways in OHCA since 1991

• In 2004 some EMS personnel were trained in ET intubation after 62 hours of additional training and 30 successful intubations– Choice of airway up to technician– Advanced airway placement limited to 2 attempts

and confirmed by ET CO2 monitor

Data Collection

• All adults aged 18 years or older who had OHCA and who had resus attempted by EMS personnel and were subsequently transported to hospitals between Jan 2005 & Dec 2010

• Used All-Japan Utstein Registry of the Fire & Disaster Management Agency [ambulance service]– EXCLUSIONS: incomplete documentation

Data Collection 2• Utstein-style form

contains considerable amount of data• Sex• Age• Etiology of arrest• Bystander witnesses• Type of bystander CPR• Admin of adrenaline• Airway management

technique used

Demographics similar in both groups

End Points

• Outcome measures:– ROSC before hospital arrival– 1-month survival– Neurological status 1 month after the event

• Determined by treating physician, if patient was not at the hospital the EMS conducted their own follow-up

• Neurological outcome – Glasgow-Pittsburgh cerebral perfusion category– 1 (good performance) or 2 (moderate disability)– 3, 4 & 5 regarded as unfavourable outcomes

Data Analysis

• Any advanced airway vs BVM• ETT vs supraglottic airway vs BVM

• 3 separate analyses (multi-variate linear regression analyses)– Unadjusted– Adjusted for selected variables• (age, sex, cause, initial rhythm, ?witnessed, type of

bystander CPR, use of AED, adrenaline, time intervals– All variables in Table 1 + geographical location

• Propensity score matching to help address selection bias (AA vs BVM)

Results 1 – Unconditional

Overall outcomes of all airway techniques: 6.5%, 4.7%, 2.2%P <0.001 for all

2.9% 1.0% 1.1%

7.0% 8.4%

Results 2 – Conditional (propensity matched)

Favourable neurological outcome - 1.0% vs 3.2%

Favourable neurological outcome – 1.1% vs 3.2%

Comment• CPR with advanced airway management is a

significant predictor of poor neurological outcome compared to BVM ventilation– ETT and supraglottic devices

• ?Reasons– Attaining and maintaining AA competency

• US, Pennsylvania, mean 1 ETT/year amongst trained EMS– Procedural experience with out-of-hospital endotracheal intubation. Crit Care Med. 2005;33(8):1718-1721

– ETT associated adverse events• Oesophageal intubation, tube displacement, hypoxaemia,

bradycardia

– Interruption of BLS procedures– Increased intrathoracic pressure reduced perfusion

pressure – coronary & cerebral

Limitations• Observational study– Negative association does not necessarily prove causation

• Much smaller proportion of total OHCA are intubated (6%) compared to BVM (57%)/supraglottic (36.9%)

• Does not account for different experience/training amongst EMS– No data on failed ETT/supraglottic airways reverting to

BVM– No guarantee that the 2 attempts rule was adhered to

Limitations 2• Patients who had ROSC prior to any advanced

airway intervention probably more likely to have had better neurological outcome due to early ROSC, rather than use of BVM

• Does not account for variability in post-resus care eg. active cooling

• ROSC in unconditional analysis more likely in ETT group vs BVM group– Consistent with other studies showing ETT to be

positive factor in survival to hospital• Out-of-hospital cardiac arrest in Victoria: rural and urban outcomes. Med J Aust 2006;185(3):135-139

Discussion

• Overwhelming belief among majority of healthcare providers that ETT is the gold-standard– Lack of equipoise– Therefore a prospective randomised trial would

be difficult