We have only ever been formally taught to use assisted ventilations in patients with poor oxygenation who are in life threatning respiratory distress eg an asthmatic patient who is exhausted or cardiogenic pulmonary edema where the patient is not ventilating adequately to oxygenate.
Are you taught something different and if so what is the rationale behind it?
Hello Brown,
Hopefully I can help to address your question.
The logic behind our teaching (at least in Ontario, Canada) is that if someone is breathing less than 8 times a minute or more than 28 times a minute, chances are their breathing is not effective.
One of our books provides the following example: If the average person breathes in 500mL of air with each breath, and breaths about 15 times a minute (on average) - they will be breathing in approximately 7.5L of air each minute. Having said that, in order to get (approx.) 500mL of air....one must inhale for a second or two and exhale for another second or two. With that in mind, if someone is breathing at 30-40 breaths a minute, they likely are not taking in enough oxygen, despite the rapid breathing (as each breath may only have 100-200 mL of air, resulting in an inadequate oxygen supply (or so the theory goes...).
Conversely, if a person is breathing at less than 8 times a minute (especially if unconscious and/or obvious signs of poor perfusion), they likely are not able to draw adequate oxygen levels (unless they are taking huge breaths and even then....it seems rather unlikely).
Having said that, tools, such as the PulseOx can help us to back up our decision weather to bag or not...and, as previously stated, one must exercise some common sense, and take into account factors like, the appearance of the patient, the rhythm and quality of the respiration's (not just rate), whether or not coaching the breathing (especially if its too fast) will be beneficial (i.e. if the patient is unconscious, its highly probable that coaching isn't going to do much good).
Hopefully the above explanation will help to answer your question with respect to the rationale about as assisting with ventilations.
Best regards,