Also one more question, do you think 100ug of fentanly is too much for someone in severe pain?
No, not for most patients.
What's too much is a dose that causes hypotension, respiratory depression, apnea, or loss of control of airway reflexes. For most people this will be more than 100ug.
I read that 100 of fentanyl is compared to 10mg but I think it is acceptable because it doesnt produce the respiratory depression like morphine. Any thoughts?
Fentanyl can cause respiratory depression / apnea as well.
For most people 10mg of MS isn't too much for severe pain. What's too much is a dose causing hypotension, respiratory depression, apnea, or loss of control of airway reflexes. A reasonable analgesia dose of MS is somewhere around 0.1 mg / kg, which for a larger person is close to 10mg. Most of us have just been terrified into giving smaller doses, e.g. the homeopathic 2mg MS IVP.
You have to accept that there's a huge amount of interpatient variability. You will see some people get very very sleepy with even a relatively small dose of morphine or fentanyl. And it's not always the 45 kg geriatric patient, sometimes it's the big 110kg ex-football player.
There's also a lot of unpredictability if you are mixing benzodiazepines with opiates. If you're going to do this, you need to be aware that they're synergistic, and a small amount of the two in combination go a long way.
I think an intelligent approach is to give moderate quantities on a repeat basis until the pain is manageable. You can always give more, but you can't take it back if you give too much.
I've given 30mg of MS IVP to an end-stage cancer patient with chronic pain (*After consulting with a palliative MD). I've also given a four year old child 14mg of MS after they poured a pot of boiling water over themselves. There's no fixed magic number that's "too much", it depends on the patient in front of you, and how they respond to initial and subsequent doses.