Table 4.
Pain assessment results per measurement method.
| Method | Subjects | Able pain measure | Consistent across studies∗ | Limitations | |
|---|---|---|---|---|---|
| Electroencephalogram (EEG) | Neonates, infants, CPPs, ICU patients | Yes | Moderate | Influenced by opioids, not consistently found in neonates | |
|
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| Cardiovascular measures | Heart rate | Neonates, infants, TBI patients, ICU/OR patients, CPPs, people with SID, healthy adults | Doubtful | No | Variable results among brain injured patients, reduced reaction in CPPs, no reaction in SID |
| Heart rate variability | Neonates, infants, ICU/OR patients, healthy adults | Yes | Moderate | Inconsistent among infants in the first year of life | |
| Body temperature | Neonates, infants, healthy adults | Yes | Moderate | Inconsistent among healthy adults | |
| Blood pressure | Neonates, infants, TBI patients, OR patients, healthy adults | Doubtful | No | Blood pressure responded inconsistently to pain | |
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| Respiratory measures | Respiratory rate | Neonates, infants, TBI patients, people with SID, healthy adults | Yes | Yes | Respiratory ‘irregularities' were not related to acute pain in persons with SID |
| Respiratory analysis | Neonates, infants, TBI patients | Yes | Yes | Oxygen saturation was not favored for pain in neonates | |
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| Muscular measures | Muscle tension | Infants, ICU/OR patients, healthy adults | Yes | Yes | In healthy adults muscle tension response was only found with intense and prolonged pain |
| Electromyogram | CPPs, healthy adults | Yes | Yes | Few studies | |
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| Electrodermal activity | TBI patients, OR patients, healthy adults | Doubtful | No | Only consistently found in healthy adults | |
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| Pupillometry | Infants, OR patients, CPPs, healthy adults | Yes | Yes | Few studies | |
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| Brain scan | MRI | CPPs, healthy adults | Yes | Yes | Different studies focused on different areas |
| NIRS | Neonates, infants | No | Yes | Presence of pain on a cortical level was not found | |
| CBFV | Infants, CPPs, OR patients, people with SID | Yes | Yes | Few studies | |
| SPECT | Infants, CPPs | Yes | No | Activity varied greatly across studies | |
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| Hormonal analysis | Neonates, CPPs | Yes | Yes | Few studies | |
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| Genetics | CPPs, healthy adults | Yes | Yes | Not yet validated in large human cohorts | |
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| Automatic facial recognition | CPPs | Doubtful | Yes | Influenced by gender, age, ethnicity, movement, and lighting | |
Note. CPPs = chronic pain patients, ICU = intensive care unit, OR = operating room, TBI = traumatic brain injury, SID = severe intellectual disability, MRI = magnetic resonance imaging, NIRS = near-infrared spectroscopy, CBFL = cerebral blood flow velocity, PET = positron emission tomography, and SPECT = single-photon emission computer tomography. ∗ [2, 10–37].