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capnography in ICU

NPR news and capnography

[4 min 37 sec]
Howard Snitzer's heart stopped beating for 96 minutes last January. First responders didn't give up on him, thanks in part to capnography, a technology that let them know Snitzer still had a chance of coming back.
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Howard Snitzer's heart stopped beating for 96 minutes last January. First responders didn't give up on him, thanks in part to capnography, a technology that let them know Snitzer still had a chance of coming back.

August 22, 2011

Last January, a Minnesota man's heart stopped beating for an amazing 96 minutes. Emergency room doctors thought he was dead. But first responders who gave CPR on the scene decided not to give up, in part because of technology that allowed them to see their efforts were working.

It's called capnography, and it measures how much carbon dioxide is being expelled with each breath. This information helps doctors and emergency medical personnel determine whether a patient is hyperventilating or having a heart attack. It also helps them decide how to treat an asthma attack, or determine whether CPR is working.

How It Works

At a fire station in Brook Park, Ohio, medical officers put a tube in my nose and hook me up to the machine to show me how it works.

"OK, that last data stream there is the capnography. Now just breathe normal," Lt. Mark Lynch says, pointing at a graph on the screen that moves up and down when I breathe.

I watch the monitor as I inhale and exhale. "Every time I breathe out, it goes up," I remark.

"Yes. That's the exhalation. Right," Lynch confirms.

There is also a number on the screen that corresponds to the carbon dioxide I exhale — an estimate of carbon dioxide levels in my blood. As I change my breathing, the number changes, too. By breathing rapidly, I blow out carbon dioxide, and the number on the screen goes down. If I hold my breath, it goes up. Lynch explains that if I were unconscious and receiving CPR, the carbon dioxide levels would tell them how efficiently their chest compressions were pumping blood through my lungs and to my organs. Breathing normally, my number is 35.

"Now, during good CPR, this is probably going to be around 25 — if you keep this up in that 25 range, then there's circulation still going on. ... That's where you're going to get a positive outcome," Lynch says.

Capnography is not a new technology. In fact, it's been around for years, used by anesthesiologists to monitor a patient's breathing during surgery.

But these days, the technology is making its way out of hospital operating rooms and into portable devices that are helping first responders make critical — sometimes life-saving — decisions.

Knowing When Not To Quit

That was certainly the case for Howard Snitzer when he collapsed in front of a Minnesota grocery store one cold night last January. After he woke up days later, some of the emergency medical personnel who helped that night told him what had happened.

"They said, 'We were wondering what you remember about your heart attack.' And I said, 'Nothing.' And they said, 'Well, here's what we remember.' And they started telling this story, and I was just blown away," Snitzer recalls.

For more than an hour and a half, Snitzer had no pulse. Emergency room doctors said there was nothing more they could do. But one of the flight nurses who had come with the emergency helicopter had been trained in capnography. Snitzer's carbon dioxide levels suggested that blood was flowing to vital organs like the heart and brain, and the nurse thought Snitzer still had a chance.

The nurse "called the emergency room doctor, who told him that I was dead and that they should walk away," says Snitzer. "And he hung up and he said to the rest of the people in the room, 'Is anyone else here uncomfortable with walking away from this?' And they all said yes. And it was at that point that he called Dr. White."

That's Dr. Roger White, an anesthesiologist at Mayo Clinic. He's the one who finally came up with the solution to get Snitzer's heart beating normally again.

"We just continued believing that the measurement of carbon dioxide pressure said that if we can stop that fatal rhythm, Howard will be OK," White explains.

After shocking Snitzer's heart 12 times and administering intravenous drugs, they finally did manage to stop that fatal heart rhythm. When a pulse and a regular heartbeat had been restored, Snitzer was airlifted to the Mayo Clinic.

White says that before the use of capnography, the only way of assessing blood flow to vital organs was by feeling for a pulse or by looking for dilated pupils. He says those methods are very crude and can fail. Snitzer never had a pulse despite good carbon dioxide readings. Without the information from capnography, he says, it would have been reasonable to stop CPR — and Snitzer likely would have died.

"The lesson that I certainly learn from this is you don't quit — you keep trying to stop that rhythm as long as you have objective, measurable evidence that the patient's brain is being protected by adequate blood flow as determined by the capnographic data," says White.

Capnography is slowly becoming standard equipment for emergency responders. Next year, the fire department in Brook Park will have five new capnography machines — as opposed to the one they have now.

The American Heart Association added capnography to its 2010 guidelines for treating cardiac arrest patients — a sign, says White, that it's a technology that emergency medical teams can no longer do without.

96 minute of CPR with capnography

During CPR, capnography does help to gauge the effectiveness of CPR. Effective CPR can facilitate enough cerebral and pulmonary circulation. The pulmonary circulation can be indirectly monitored by capnographic waveform and end tidal carbon dioxide values. The following video illustrates the values of capnography during CPR.





CPR and Capnography

Since the current guidelines of ACLS, and AAGBI recommend capnography during CPR, we have adapted the following. The movable stand is equipped with code box, capnograph, and a Video laryngoscope for unanticipated difficult intubation when called for a code


Bhavani Kodali MD CPR and capnography 












Time for capnography - Everywhere

Time for capnography - everywhere

This title is based on the editorial by DR Whitaker in Anaesthesia 2011;66:544-9 titled "Time for Capnography - Everywhere" 

Anesthesiologists have adopted capnography as a standard of monitoring in operating rooms for 25 years. Despite proven value of capnography in operating rooms, its use in outside of the operating rooms has not matched that in the operating rooms. Anesthesiologists have understood the value of capnography and pulse oxymetry 25 years ago and did not wait for randomized control studies to prove their value in clinical practice before their introduction. Due credit should be given to the anesthesiology leadership at the American Society of Anesthesiologists, Anesthesiology Association of Holland, and Association of Anesthetists of Great Britain and Ireland to implement capnography as a standard of care based on predictive conclusions of retrospective analysis.  This has probably made anesthesia safer in the operating rooms.   What about outside of operating rooms? The reasons may be many. Instead of debating on the reasons why capnography has not become a standard outside of OR / OT, it is time to implement its use now everywhere outside of operating rooms, wherever, intubations, ventilations, and sedations take place. The current evidence, based on what can considered as a controlled study comparing the outcomes with and without capnography, should decisively go in favor of implementing capnography outside of OR /OT. The data from the studies show that in 2008-9 there were 16 airway deaths from the 3 million patients undergoing general anesthesia monitored with continuous capnography, giving a death rate of 1:180,000. Similarly, there were 18 deaths from a much smaller number of ICU patients receiving ventilation: 48000 during the study year, giving a death rate of 1 in 2700. This implies that it is 66 times more likely to have airway catastrophes in ICU where capnography is not used as compared to operating room where continual capnography is the standard of care. What is more alarming is the conclusion of the study group that 74% of ICU airway deaths could have likely been prevented had continuous capnography been used. This led to several recommendations to be implemented.

 British Journal of Anaesthesia 2011;106(5):632-42

In Intensive Care Unit: 

1.Capnography should be used for intubation of all critically ill patients irrespective of location.

2. Continuous capnography should be used in all ICU patients with tracheal tubes (including tracheostomy) who are intubated and ventilator-dependent. Cost and technical difficulties may be practical impediments to the rapid introduction of routine capnography. However, these need not prevent its implemenation.

3. Where capnography is not used, the reason should be documented in the chart.

4. Training of all clinical staff who work in ICU should include interpretation of capnography. Teaching should focus on identification of airway obstruction or displacement.  In addition, recognition of the abnormal (but not flat) capnograph trace during CPR should be emphasized.  

In Emergency Unit:

1.  Capnography should be used for all intubations in the ED

2. Capnography should be used for all anesthetized patients in ED

3. Capnography should be used for intubated patients during transfers from the ED to other departments.  



AAGBI Safety Statement on Capnography

This is reproduced from the Association of Anaesthetists of Great Britain and Ireland
The use of capnography outside the operating theatre  
Updated statement from the Association of Anaesthetists of Great Britain & Ireland 
(AAGBI) May 2011
The AAGBI publications ‘Recommendations for standards of monitoring during 
anaesthesia and recovery’ (4 th  edition) 2007 (1) and ‘Capnography outside the operating 
room’ 2009 (2) recommend continuous capnography in all patients who are 
anaesthetised or intubated, regardless of their location in the hospital, or the type of 
airway device used. In addition, continuous capnography is recommended for all 
patients undergoing deep sedation or any sedation where the airway cannot be directly 
observed, and should be immediately available during the treatment of cardiac arrest. 
Whilst the use of capnography is routine in the operating theatre, this is not so in other 
areas of hospital practice, and the AAGBI recognises that the practice of moderate 
sedation using agents such as propofol is increasing. The AAGBI would also like to alert 
the membership to two important recent publications and to strengthen our 
recommendations on the routine use of capnography. This has the potential to have a 
major impact on deaths due to airway complications outside the operating theatre (5). 
1. The 2010 International Consensus Guidelines on Cardiopulmonary 
Resuscitation (3) and the Resuscitation Council UK Resuscitation Guidelines 
2010 (4) emphasise the importance of capnography during cardiopulmonary 
resuscitation to continually monitor tracheal tube placement and quality of CPR 
and to provide an early indication of return of spontaneous circulation.
2. The fourth National Audit Project ‘Major complications of airway management’ 
(NAP4) was published in March 2011 (5) and raised particular concerns about 
complications of airway management in ICU and the emergency department. At 
least one in four major airway complications reported to NAP4 was from the 
ICU or the emergency department and more than 60% of events in the ICU led 2
to death or brain damage. Common factors in both the ICU and emergency 
department included unrecognised oesophageal intubation or unrecognised 
displacement of tracheal tubes or tracheostomy tubes after patient movement, 
intervention, or during transport. Capnography was frequently absent or a flat 
capnography trace due to airway displacement was misinterpreted during 
cardiopulmonary resuscitation. The absence of capnography, or the failure to 
use it properly, contributed to 80% of deaths from airway complications in the 
ICU and 50% of deaths from airway complications in the emergency 
The AAGBI recommends that:
• Continuous capnography should be used in all anaesthetised patients, 
regardless of the airway device used or the location of the patient.
• Continuous capnography should be used for all patients whose trachea is
intubated, regardless of the location of the patient (see note 1).
• Continuous capnography should be used for all patients undergoing moderate 
or deep sedation, and should be available wherever any patients undergoing
anaesthesia or moderate or deep sedation are recovered (see note 2).
• Continuous capnography should be used for all patients undergoing advanced 
life support (see note 3).
1. Patients with tracheostomy tubes and who are also breathing spontaneously 
without ventilator support or continuous positive airway pressure (CPAP) do not 
normally require continuous capnography.
2. Sedation is a continuum and it is not always possible to predict how an 
individual patient will respond. Moderate Sedation/ Analgesia (“Conscious 
Sedation”) is a drug-induced depression of consciousness during which patients 
respond purposefully to verbal commands, either alone or accompanied by 
light tactile stimulation. No interventions are required to maintain a patent 
airway, and spontaneous ventilation is adequate…Deep Sedation/ Analgesia is a 
drug-induced depression of consciousness during which patients cannot be 
easily aroused but respond purposefully following repeated or painful 
stimulation. The ability to independently maintain ventilatory function may be 
impaired. Patients may require assistance in maintaining a patent airway, and 
spontaneous ventilation may be inadequate (6).3
3. The AAGBI recognises that capnography is not yet standard on resuscitation 
trolleys, but notes that a number of companies produce defibrillators with 
integrated capnography. The AAGBI recommends that capnography should be 
available and delivered promptly to any patient undergoing advanced life 
1. AAGBI Recommendations for standards of monitoring during anaesthesia and 
recovery’ 2007 (4th  edition) (accessed 
24th May 2011)
2. AAGBI Capnography outside the operating room’ 2009
df (accessed 24 th  May 2011)
3.Deakin CD, Morrison LJ, Morley PT.  2010 International Consensus on 
Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science 
with Treatment Recommendations Part 8: Advanced life support. Resuscitation
2010; 81s: 93–174.
4.Resuscitation Council (UK) Resuscitation Guidelines 2010 (accessed 24th May 2011)
5.4th  National Audit of the Royal College of Anaesthetists and the Difficult Airway 
Society: Major complications of airway management 2011 Ed Cook T, Woodall 
N, Frerk C (accessed 24th May 2011)
6.ASA Committee on Quality Management and Departmental Administration: 
Continuum of depth of sedation, definition of general anesthesia and levels of 
sedation/analgesia (approved by ASA House of Delegates on October 27th
2004 and amended on October 21st 2009) (accessed 17th June