Can Patient’s Heart Rate measure pain severity ?

Your patient reports severe 10 / 10 pain demanding more narcotics but also looks comfortable, jokes with staff while enjoying TVs shows & sleeps great -sound familiar ? The above images were generated using free ‘text-to-image AI software’. The top images are “severe pain” and lower are “moderate pain”. See anyone joking & watching TV ? Disregard my RJF (Resting Judging Face) 😑 – In reality pain response is complex, inconsistent & fickle – genetic, experential, racial , emotional , upbringing, etc aspects play into it. We already covered Redheads and pain before. But I do wish there was a ‘BNP of pain’ to measure pain severeity when you just want to weed out the “narcotic seekers” or gently push back on family who get traumatized and ‘feel the pain’ of their loved one and demand “absolutely zero pain” thus risking overdose & side-effects. The pain scale I love to bring up in these situations is the Improved pain scale ( I replace the 10/10 one with “man on fire” and ask if a man on fire would be sleeping or watching TV and ordering pizza ?

In my quest for finding indirect evidence of pain, I wondered if Heart Rate could be a proxy of pain severity. Real pain should amp up adrenaline with sympathetic response and elevate heart rate ? But then anxiety about the pain or ‘catastrophizing’ the pain raises heart rate too as published in this 2021 study. A few studies done in the past failed to a strong & consistent correlation to pain scores & heart rate. A analysis published in 2016 saw mild correlation in whites but not objectively significant to use consistently as a measure of severity – this table summarizes a sample in that analysis. I still consider heart rate in situation when it was elevated with a real injury such as a fracture and later is normalized and patient still complaints of high pain levels, that’s when the psychological component needs addressing.

‘Heart Rate Variability’ (HRV) however is showing some promise in not only indicating the sympathetic tone response (lesser the heart rate variability more the sympathetic tone) but also as a way of assessing effectiveness of pain interventions themselves via HRV feedback. A good 2022 review is published here. Maybe all hospital monitors should include this measure as a standard on their screens as an additional way to judge pain?