Interesting piece. I’d like to add a little something to your understanding of respiratory and cardiovascular physiology though. The respiratory system is mostly controlling the pH of our blood. Increasing CO2 leads to acidosis and acidosis leads to ineffective function of many of our hormones like epinephrine and norepinephrine so it actually makes sense to have pH as the trigger. One can actually survive with very low levels of blood oxygen as long as blood pH is maintained which is via circulation and ventilation. Ventilation meaning CO2 removal and circulation meaning keeping blood flowing
It has been demonstrated that one can do completely effective CPR with chest compressions only and no mouth to mouth breathing. Many CPR classes now teach that providers simply pump on the chest 100-110 times per minute. Many people don’t do effective breathing any way and are rightfully concerned about doing mouth to mouth on a stranger. Keeping blood flowing with compressions eliminates CO2 ( because there is still some ventilation from the chest compressions alone) There have been witnessed cardiac arrests where ONLY chest compressions were done for over an hour and patient survived. A key point here is “witnessed” arrest. As long as compressions are started promptly survival is possible. Each minute matters. CO2 rises 4-6 mmHg per minute for first couple minutes and about 2-4 each subsequent minute so five minutes of apnea /loss of circulation leads to increase of CO2 of almost 20mmHg. Quite significant
Thanks for the kind words and for the comment. This is very helpful additional information, so thanks for sharing this. It’s quite striking to me that CPR is effective with only chest compressions. I was completely unaware of that fact. (Full disclosure, it did not occur to me to include the material about mouth-to-mouth resuscitation when I wrote this. I got some very helpful feedback from a friend who is an expert in this area, otherwise I would have missed this connection altogether.) In any case, thanks for providing this additional material. Very interesting.
Glad to add some insight! It’s important to note that while it’s entirely possible to successfully resuscitate someone with compressions only, it is better to have respiratory support as well when it is available. Problem is it’s not always available (outside of mouth to mouth) and most lay people can’t do it effectively. Anyone can be shown how to compress a chest properly and most anyone over 80 pounds can get the proper depth of compression when using good technique. Establishing an airway is very difficult for most people and if time is wasted trying to do that successful resuscitation is unlikely.
Most people who arrest arent successfully resuscitated to the point of leaving the hospital Much is dependent on the reason for arrest and the baseline condition of patient.
Many lives have been saved with prompt effective intervention but most arrests are fatal
Interesting piece. I’d like to add a little something to your understanding of respiratory and cardiovascular physiology though. The respiratory system is mostly controlling the pH of our blood. Increasing CO2 leads to acidosis and acidosis leads to ineffective function of many of our hormones like epinephrine and norepinephrine so it actually makes sense to have pH as the trigger. One can actually survive with very low levels of blood oxygen as long as blood pH is maintained which is via circulation and ventilation. Ventilation meaning CO2 removal and circulation meaning keeping blood flowing
It has been demonstrated that one can do completely effective CPR with chest compressions only and no mouth to mouth breathing. Many CPR classes now teach that providers simply pump on the chest 100-110 times per minute. Many people don’t do effective breathing any way and are rightfully concerned about doing mouth to mouth on a stranger. Keeping blood flowing with compressions eliminates CO2 ( because there is still some ventilation from the chest compressions alone) There have been witnessed cardiac arrests where ONLY chest compressions were done for over an hour and patient survived. A key point here is “witnessed” arrest. As long as compressions are started promptly survival is possible. Each minute matters. CO2 rises 4-6 mmHg per minute for first couple minutes and about 2-4 each subsequent minute so five minutes of apnea /loss of circulation leads to increase of CO2 of almost 20mmHg. Quite significant
Thanks for the kind words and for the comment. This is very helpful additional information, so thanks for sharing this. It’s quite striking to me that CPR is effective with only chest compressions. I was completely unaware of that fact. (Full disclosure, it did not occur to me to include the material about mouth-to-mouth resuscitation when I wrote this. I got some very helpful feedback from a friend who is an expert in this area, otherwise I would have missed this connection altogether.) In any case, thanks for providing this additional material. Very interesting.
Glad to add some insight! It’s important to note that while it’s entirely possible to successfully resuscitate someone with compressions only, it is better to have respiratory support as well when it is available. Problem is it’s not always available (outside of mouth to mouth) and most lay people can’t do it effectively. Anyone can be shown how to compress a chest properly and most anyone over 80 pounds can get the proper depth of compression when using good technique. Establishing an airway is very difficult for most people and if time is wasted trying to do that successful resuscitation is unlikely.
Most people who arrest arent successfully resuscitated to the point of leaving the hospital Much is dependent on the reason for arrest and the baseline condition of patient.
Many lives have been saved with prompt effective intervention but most arrests are fatal