Rethinking bystander CPR for out-of-hospital cardiac arrest

Background Mouth-to-mouth ventilation is a barrier to bystanders doing cardiopulmonary resuscitation (CPR), but few clinical studies have investigated the efficacy of bystander resuscitation by chest compressions without mouth-to-mouth ventilation (cardiac-only resuscitation). Methods Objective: To compare the effect of bystander-provided cardiac-only resuscitation to conventional CPR in adults who had out-of-hospital cardiac arrest. Design: Prospective multicenter observational study. Setting: 58 emergency hospitals and emergency medical service units in the Kanto region of Japan. Subjects: Patients with witnessed out-of-hospital cardiac arrest who were subsequently transported by paramedics to participating emergency hospitals. Exclusion criteria were age <18 years, further cardiac arrest after the arrival of paramedics, documented terminal illness, presence of a do-not-resuscitate order, and bystander resuscitation without documented chest compressions. Intervention: None. On arrival at the scene, paramedics assessed the technique of bystander resuscitation, recording it as conventional CPR (chest compressions with mouth-to-mouth ventilation), cardiac-only resuscitation (chest compressions alone), or no bystander CPR. Patients were followed and revaluated 30 days after the arrest to determine neurologic status. Outcome: The primary endpoint was favorable neurological outcome 30 days after cardiac arrest using the Glasgow-Pittsburgh cerebral-performance scale, with favorable neurological outcome defined as a category 1 (good performance) or 2 (moderate disability) on a 5-point scale. Results 4068 adult patients who had out-of-hospital cardiac arrest witnessed by bystanders were included; 439 (11%) received cardiac-only resuscitation from bystanders, 712 (18%) conventional CPR, and 2917 (72%) received no bystander CPR. Any resuscitation attempt was associated with a higher proportion having favorable neurological outcomes than no resuscitation (5.0% vs 2.2%, p<0.0001). Cardiac-only resuscitation resulted in a higher proportion of patients with favorable neurological outcomes than conventional CPR in patients with apnea (6.2% vs 3.1%; p=0.0195), with shockable rhythm (19.4% vs 11.2%, p=0.041), and with resuscitation that started within 4 min of arrest (10.1% vs 5.1%, p=0.0221). However, there was no evidence for any benefit from the addition of mouth-to-mouth ventilation in any subgroup. The adjusted odds ratio for a favorable neurological outcome after cardiac-only resuscitation was 2.2 (95% CI 1.2-4.2) in patients who received any resuscitation from bystanders. Conclusions Cardiac-only resuscitation by bystanders is the preferable approach to resuscitation for adult patients with witnessed out-of-hospital cardiac arrest, especially those with apnea, shockable rhythm, or short periods of untreated arrest.