Many of you may have seen the recent news story about bystander CPR without mouth to mouth.
Here’s the link:
And here’s the study abstract:
The Lancet 2007; 369:920-926
Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study
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).
We did a prospective, multicentre, observational study of patients who had out-of-hospital cardiac arrest. On arrival at the scene, paramedics assessed the technique of bystander resuscitation. The primary endpoint was favourable neurological outcome 30 days after cardiac arrest.
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 favourable neurological outcomes than no resuscitation (5·0% vs 2·2%, p<0·0001). Cardiac-only resuscitation resulted in a higher proportion of patients with favourable neurological outcomes than conventional CPR in patients with apnoea (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 favourable neurological outcome after cardiac-only resuscitation was 2·2 (95% CI 1·2–4·2) in patients who received any resuscitation from bystanders.
Cardiac-only resuscitation by bystanders is the preferable approach to resuscitation for adult patients with witnessed out-of-hospital cardiac arrest, especially those with apnoea, shockable rhythm, or short periods of untreated arrest.
Recently I have been attaching the capnofilter to my ET tube before I intubate. The following are typical ETCO2 strips on intubation. The tiny bumps are CPR, each compression creates a small tidal volume that releases CO2, ventilating the body by compression only. The large wave is from the first ambu-bag ventilation on the just placed ET tube.
To me this is proof that compression only CPR, provides some degree of ventilation by itself.
I listened to a podcast from the Lancet (3-17-07) magazine, which published the study, and the author notes that compression only CPR is meant for bystanders only and is effective only in primary cardiac arrest and not arrests due to respiratory causes. The key difference being in cardiac arrest (presumably patients in v-fib), the blood is still largely oxygenated — at least for the first five minutes, there are ample energy stores and the body isn’t yet acidic. In respiratory induced cardiac arrest, the blood is desaturated.
Speaking of the difference between cardiac and respiratory induced cardiac arrests, check out this study on using capnography to differentiate the causes of arrest.