The November 2009 issue of the Annals of Emergency Medicine has a new study called Interruptions in Cardiopulmonary Resuscitation from Paramedic Endotracheal Intubation.
With all the science showing the benefits of uninterrupted cardiac compressions, the investigators asked the question: Since nearly every out-of-hospital cardiac arrest patient gets an intubation attempt, how do intubation attempts affect the CPR?
Using a prospective observational study design, they looked at two Pittsburgh EMS Agencies, both participants in the Resuscitation Outcomes Consortium: an urban service – 14 – 2 medic ambulances – 65,000 calls per year and a a county rural based agency with 27 single paramedic ambulances doing 60,000 calls per year. Both top flight, well-trained services with strong involved medical direction.
They recorded consecutive out of hospital cardiac arrests receiving EMS resuscitation and endotracheal intubation attempts from November 1, 2006 to June 20, 2007. They excluded pediatric patients (<18 years), major trauma, and patients where an advanced airway was not attempted.
They used cardiac monitors that continuously recorded ECG rhythm, ventilations, ETCO2, and chest compressions. They were also equipped with audio recorders.
They identified all CPR interruptions (CPR stops for 5 seconds or more). The interruptions were not just ET attempts, but also tube confirmations, adjustments, securing the tube, etc. They combined digital information with audio to determine what was going on.
Their outcome measures were the number of CPR interruptions and the duration of the CPR interruptions.
Of 182 arrests, they excluded 82 for the following reasons: 4 pediatric, 15 intubated before start of CPR recording, 18 no advanced airway, 6 No resuscitation attempted, 1 not cardiac arrest, 38 incomplete data.
The 100 patients broke down as follows: 61 male, 39 female, 42 witnessed arrests, 36 bystander CPR, 6 EMS witnessed arrests, 21 VF/VT, 100 intubation attempted, 79 ET tube, 8 combi, 5 King LT, 5 bag-valve, 73 transported and 24 ROSC.
Here are the results: median of 2 CPR interruptions, range from 1-9 interruptions, and median time to first ET attempt was 246 seconds.
Median duration of 1st ET attempt was 45 seconds (range from 7 to 221 seconds), 30% of cases 1st ET attempt exceeded one minute, some cases have interruptions lasting 4 minutes.
Subsequent interruptions broke down as follows; median duration was 35 seconds per CPR interruption, median total interruptions was 109.5 seconds per patient, 25% of patients had more than 3 minutes of interruption, some cases had 7 minutes of interruptions.
Interruptions associated with intubation had a median duration was 35 seconds per CPR interruption, median total interruptions was 109.5 seconds per patient, 25% of patients had more than 3 minutes of interruption, some cases had seven minutes of ET interruptions.
Limitations to the study were as follows: excluded patients may have altered data, using well-trained, high-acuity systems may show fewer interruptions than in less well-trained systems, study did not examine effect of number of rescuers on scene, and the study could not determine if ET attempts occurred during CPR.
The bottom line: paramedic out-of-hospital endotracheal intubation efforts were associated with multiple and prolonged CPR interruptions.
In an accompanying editorial, Do Not Pardon the Interruptions the authors made the following points;
1. Many aspects of current out-of-hospital cardiac arrest management lead to detrimental loss of circulation during CPR.
2. Interruption intervals, although significant, actually underestimate, the amount of time that circulation is compromised because of the “ramp-up” period required to restore adequate circulation on resumption of compressions.
3. There is no evidence that tracheal intubation contributes to survival in out-of-hospital cardiac arrest.
“For at least the first 5 to 10 minutes of resuscitation providers should prevent interruptions of chest compressions for anything other than single defibrillatory attempts and intentionally delay tracheal intubation before return of spontaneous circulation.”
The 2005 American Heart Association Guidelines had much to say out about what was once considered the gold standard of airway protection:
Rescuers must be aware of the risks and benefits of insertion of an advanced airway during a resuscitation attempt.
Because insertion of an advanced airway may require interruption of chest compressions for many seconds, the rescuer should weigh the need for compressions against the need for insertion of an advanced airway.
Rescuers may defer insertion of an advanced airway until the patient fails to respond to initial CPR and defibrillation attempts or demonstrates return of spontaneous circulation
It is important to remember that there is no evidence that advanced airway measures improve survival rates in the setting of prehospital cardiac arrest.
Interruptions needed for intubation can be minimized if the intubating rescuer is prepared to begin the intubation attempt (ie, insert the laryngoscope blade with the tube ready at hand) as soon as the compressing rescuer pauses compressions.
The compressions should be interrupted only as long as the intubating rescuer needs to visualize the vocal cords and insert the tube.
The compressing rescuer should be prepared to resume chest compressions immediately after the tube is passed through the vocal cords.
There are some services in the country who are now forbidding their medics to intubate v-fib arrests in the first ten minutes or more of resuscitation.
Some are arguing the medics should simply forgoe ET intubation altogether for the immediate insertion of a supraglottic airway.
What will the 2010 AHA Guidelines have to say on this issue? Will the march away from intubation continue? We’ll have to wait and see.
In the meantime how will this study effect my practice?
First, let me say, I love intubating. For some childish hubristic reason every time I intubate I feel like I am more of a medic. When someone asks I want to have an impressive number of tubes to tell them.
But given all the years I have been intubating and reading this and similar studies, I have to say that my going for the tube early on in the call may not have always been in the best interests of the patient. I am a decent intubator, not a great one. I went seven years once without missing a tube (70 plus tubes). Well, to clarify, I went almost seven years where every patient I tried to intubate (who did not have a gag reflex) arrived at the hospital with an ET tube in the trachea, but that doesn’t mean I got them all quickly and on the first attempt, and it doesn’t mean there weren’t delays in CPR.
I have placed three LMAs in the last two years now after not getting an initial ET (our ET attempts have been limited to 2 now with an attempt being classified as inserting the blade in the mouth, not necessarily trying to pass the tube). I have always been bothered by how long it takes me just to get my intubation kit out and unzipped and get all the gear ready to intubate. An LMA is pretty dam quick in comparison. And then add on top of that, all the tube confirmation, securing time that is much longer with an ET than with an LMA.
And while I have intubated many patients quickly without stopping CPR for a single compression, I have had to tell people to stop on other occasions. How long have those interruptions been? I can’t say, but certainly they weren’t optimal for the patient.
Here’s what my game plan is now:
On VT/VF arrests, my mantra will be compressions and defibrillations take priority over anything else. I will delay ET. I will utilize two person bag-valve if I have enough help. I will be quicker to consider an LMA as my first line airway. If I have to intubate, I will try not to interrupt compressions at all. I will also take every attempt to practice all of my airway skills so I will best able to help my patient.
As a medic I respect recently said to someone who was questioning why she dropped a combitube in a large patient as her first airway, “I don’t have to intubate a patient to prove I am a good paramedic.”
I want to live up to that in word and in practice.