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Three Part Question

In [adult patients with out-of-hospital cardiac arrest], does the [use of CFI (continuous flow insufflation of oxygen) compared to standard ventilation strategy following paramedic guidelines] has shown [any benefits on the patient’s outcomes on his arrival and discharge from the hospital]?

Clinical Scenario

A witnessed non traumatic out-of-hospital cardiac arrest occurs in your neighbourhood and the paramedics are rapidly called on scene. Basic Life Support (BLS) guidelines are applied and ventilation may be necessary at this point.

Search Strategy

Search performed on August 4th 2017.

MEDLINE using the PubMed interface (1900 – Août 2017)

#1 - (prehospital) OR (pre-hospital) OR (EMS)// 25254 articles
#2 - (cardiac arrest) OR (out-of hospital cardiac arrest) OR OHCA // 64271 articles
#3 - (continuous flow insufflation of oxygen OR continuous insufflation of oxygen OR CFI OR B-card) // 2215 articles
#4 - #1 and #2 // 2679 articles
#5 - #2 and #3 // 13 articles
#6 - #1 and #3 // 0 article
#7 - #1 and #2 and #3 // 0 article

After reviewing the articles, 3 relevant papers were found.

In addition, reference lists of relevant papers were checked for potential studies. No new relevant studies were found. Studies on animal, cadaveric models and manakin were excluded.

B. The website www.clinicaltrials.gov was searched for ongoing trials on the subject. No trials were found.

C. Embase using the Elsevier interface (1966– August 2017)

#1 - (prehospital) OR (pre-hospital) OR (EMS)// 36335 articles
#2 - (cardiac arrest) OR (out-of hospital cardiac arrest) OR (OHCA) // 57518 articles
#3 - (continuous flow insufflation of oxygen) OR (continuous insufflation of oxygen) OR (CFI) OR B-card) // 4348 articles
#4 - #1 and #2 // 3767 articles
#5 - #2 and #3 // 13 articles
#6 - #1 and #3 // 9 articles
#7 - #1 and #2 and #3 //4 articles

After reviewing the 4 articles, 3 were duplicates from the above MEDLINE search and one was presented as a letter to the editor.

In addition, reference lists of relevant papers were checked for potential studies. No new relevant studies were found. Studies on animal, cadaveric models and manakin were excluded.

D. No BestBETs or critical appraisals were found on this topic.
E. The Cochrane Library was searched for reviews on the subject.
No reviews were found.

Search Outcome

Altogether 3 papers was found in Medline and 4 in EMBASE, of which 3 were duplicates. No papers were found by scanning the references of relevant papers. All 4 relevant papers are summarized in the table 1.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Yu H and Al 2012 China	Passive oxygen insufflation CPR (intervention group n=848) and traditional CPR (control group n=962) Adult patients, non traumatic OHCA (1810 patients)	Systematic review	Return of spontaneous circulation (ROSC)	No significant difference of ROSC (Chi2 = 1.07; P = 0.58; I2 = 0%; RR 0.93; 95% CI 0.79–1.09)	Presented as a letter to the editor. Poor explanations on methods, results and search strategies.
			Survival at discharge	No significant difference (RR 1.06; 95% CI 0.73–1.54)
Bertrand C and Al 2006 France	Standard endotracheal intubation and mechanical ventilation (MV; Control group n = 457) Use of CFIO through a multichannel endotracheal tube at a flow rate of 15 l/min (Intervention group n = 487) Comparable group characteristics Adult patients, non traumatic OHCA, not responding to initial defibrillation (n = 944)	Multicentre, Randomized Prospective, Controlled Study (RCT)	Return of spontaneous circulation (ROSC)	CFIO 21% vs MV 20% p = 0.99	Randomization scheme was changed during the study; in-depth analysis was performed only on the first cohort of 341 patients with CFIO and 355 with MV, because of randomization problems As soon as a spontaneous palpable carotid pulse was restored for a period of 1 min, standard MV using the transport ventilator was the sole mode of ventilation in both groups French EMS with ACLS and Physicians medical teams Poor prognosis population Lack of power
			Survival at hospital admission	CFIO 17% vs MV 16% p= 0.81
			ICU discharge	CFIO 2.4% vs MV 2.3% p = 0.96
			Level of detectable pulse saturation and the proportion of patients with saturation above 70%	See charts and graphics - Greater in the CIO group p = 0.005
Saïssy JM and Al 2000 France	Adult patients, non traumatic OHCA with asystole (n = 95) IPPV group (n= 47) intubated with a standard endotracheal tube and ven- tilated with standard IPPV CIO group (n=48) for whom a modified tube was inserted, and in which CIO at a flow rate of 15 L/min	Multicentre, Randomized Prospective, Controlled Study (RCT)	Return of spontaneous circulation (ROSC)	IPPV 21.3% vs CIO 27.1%	French EMS with ACLS and Physicians medical teams Poor prognosis population Analysis mainly on ROSC patient only (Gaz, hemodynamics, epinephrine doses) Low N No patient survived at 7 days
			Blood gaz analysis after ROSC	No significant difference
			Number of patients with an SpO2 more than 70% after ROSC	No significant difference
Bobrow BJ et Al 2009 USA	Adult non traumatic out-of-hospital cardiac arrest (n=1,019) Passive ventilation (PV) with non-rebreather mask intervention group (n = 459) Bag-valve-mask ventilation (BMV) control group (n = 560 ) Comparable group characteristics	Observational non-randomized retrospective study	Neuro-intact survival to hospital discharge	Adjusted OR 1.2; 0.8 to 1.9 (CI 95%)	Better population prognosis than other studies Non-randomized and retrospective design, risk of self-selection bias No specifics on CPR quality and post-arrest hospital care Passive ventilation might have been followed by endotracheal intubation at 3 min. *Witnessed ventricular fibrillation/ventricular tachycardia subset, adjusted neurologically intact survival to discharge was higher for passive ventilation (39/102; 38.2%) than bag-valve-mask ventilation (31/120; 25.8%) (adjusted OR 2.5; 95% CI 1.3 to 4.6)
			Return of spontaneous circulation (ROSC)	OR adjuste =0.8 (0.7–1.0) (CI 95%)
			Overall survival	OR adjusted=1.2 (0.8–1.9) (CI 95%)

Comment(s)

Continuous flow insufflation of oxygen doesn’t seem deleterious in OHCA patients. The French studies have showed some significant differences on non-patient oriented outcomes such as blood gazes, epinephrine doses, and hemodynamics status (SpO2) but have failed to show any benefit on survival or return of spontaneous circulation (ROSC). External validity is slightly restrained in the above studies given that those EMS systems differ from BLS-based EMS systems. Also, delivery of continuous flow insufflation of oxygen might also differ from the boussignac endotracheal multichannel tube to the oro-pharyngeal device, adding complexity to compare different studies together. The b-card device is another non-invasive open system allowing a continuous insufflation of oxygen during cardio-pulmonary resuscitation (CPR). A pre and post-implementation study using this device with Combitube in OHCA is currently underway in Quebec City.

Editor Comment

KMJ

Clinical Bottom Line

Continuous flow insufflation of oxygen does not improve survival nor ROSC compared to standard bag-mask ventilation or endotracheal intubation and mechanical ventilation in OHCA patients in different EMS systems.

References

1. Yu H., Qing H., Min Y. Continuous passive oxygen insufflation for out-of-hospital cardiac arrest: A systemic review of clinical studies Resuscitation 2013; 84 (1) , pp. e9-e10.
2. Bertrand C, Hemery F, Carli P, et al. Constant flow insufflation of oxygen as the sole mode of ventilation during out-of-hospital cardiac arrest. Intensive Care Med 2006;32:843–51.
3. Saissy JM et Al Efficacy of continuous insufflation of oxygen combined with active cardiac compression-decompression during out-of-hospital cardio respiratory arrest. Anesthesiology 2000; 92:1523–1530
4. Bobrow BJ et Al Passive oxygen insufflation is superior to bag-valve-mask ventilation for witnessed ventricular fibrillation out-of-hospital cardiac arrest. Ann Emerg Med 2009; 54:656–62