Interaction Between Sex and Cardiac Interoceptive Accuracy in Measures of Induced Pain

The Relationship Between Pain and Interoception: A Systematic Review and Meta-Analysis

Interoception refers to the ability to sense internal bodily sensations. Research suggests that dysfunctions in interoception may be implicated in the transition to chronic pain, however, little work has examined interoceptive ability in pain states. Therefore, this systematic review aimed to assess whether interoception is altered in individuals experiencing pain. Following a systematic search of 4 electronic databases from inception to February 2023, 28 studies were included. Outcomes of interoceptive accuracy, interoceptive sensibility, and interoceptive awareness were meta-analysed. The risk of bias was assessed, and the certainty of the evidence was evaluated. Meta-analyses indicated that those with chronic pain display reduced interoceptive accuracy and increased interoceptive sensibility. Subgroup analyses indicated that the change in interoceptive sensibility is dependent on the measure used, with those with chronic pain scoring higher on measures focusing on attention to bodily sensations, while also scoring lower on emotional reactivity. No difference in interoceptive awareness was observed between individuals with chronic pain and pain-free controls. Only one study was found that measured interoception in those experiencing acute pain, while another study recruited those experiencing recurrent pain. These findings suggest that while those with chronic pain self-report as more interoceptively aware, they are less accurate at detecting internal bodily signals. Further research investigating domains of interoception in those experiencing acute and recurrent pain is needed. Data should be interpreted with caution as the certainty of evidence was very low for all completed analyses. This review was registered on the PROSPERO International Prospective Register of Systematic Reviews (Registration ID = CRD42022318843). PERSPECTIVE: This review considered the relationship between interoception and pain and found that an individual's ability to accurately sense internal signals is decreased in those with chronic pain, despite them reporting being more aware of internal sensations. However, there remains little research examining interoception in non-chronic pain states.

Heart activity perception: narrative review on the measures of the cardiac perceptual ability

Measures of cardiac perceptual ability (also called cardiac accuracy) are methods of cardiac interoception, the perception of bodily sensation related to heart activity. This narrative review aims to provide an overview of these methods. We differentiate between three main measurement types: (1) change detection, i.e., when the task is to notice the change in the heart rate; also called: heart rate perception tasks, (2) discrimination tasks, i.e., when the task is to compare the internal sensations with external signal(s); also called: heartbeat detection tasks and (3) tracking tasks, i.e., when the task is to follow and report heartbeats via tapping or counting. We describe some of the new methods under "mixed methods," as they share features with more than one of the large measurement types described above. Specific measures differ in various aspects, such as their focus (heart rhythm vs. single beats), their sensitivity to non-conscious sensations and the calculated indices (e.g., whether significance level by hypothesis test is provided). When a measure of cardiac perceptual ability is chosen, it is advisable to take its characteristics into consideration in light of the planned research.

The effect of 10-week long yoga training on interoceptive abilities: cross-sectional and longitudinal investigation of cardiac and gastric accuracy

Based on their characteristics, it is likely that mind-body techniques develop interoception, the perception of bodily state. Nevertheless, findings on mindfulness, meditation, yoga, and body scan techniques are inconclusive. Additionally, the methodological scope is not exhaustive, neither in terms of the intervention nor the applied measure of interoception. This study investigated for the first time the effect of regular yoga training on cardiac and gastric perceptual ability (measured with the mental heartbeat tracking task and the water load task, respectively). With the involvement of 90 female university students (yoga group n = 57, control group n = 33) we did not find any connection between baseline heartbeat perception score and gastric fullness. Moreover, the applied 10-week-long regular yoga training did not develop any of the measured interoceptive abilities. We conclude that yoga might develop other abilities than these specific sensations. Very probably, the measured cardiac and gastric perceptual abilities do not represent bodily sensations in general. It would be worth to investigate, however, the effect of longer yoga training on interoception.

Risk factors for discontinuing intravenous patient-controlled analgesia after thoracic surgery

PURPOSE

This study examined the risk factors of experiencing side effects from using intravenous patient-controlled analgesia (IV PCA) following lung and esophageal surgery.

METHODS

Our study included adult patients who underwent lung or esophageal surgery and received IV PCA for postoperative acute pain control between 2020 and 2022. We collected information on side effects from IV PCA use, the decision to discontinue PCA, and the PCA regimen from the daily reports of the acute pain management team and verified the accuracy using electronic records from ward nurses. The primary outcome was the risk factor associated with discontinuing IV PCA due to its side effects.

RESULTS

Out of the 1796 patients in our study, 1795 used PCA containing opioids; 196 patients stopped IV PCA due to unbearable side effects. Being female (adjusted odds ratio [aOR]: 2.65, 95% confidence interval [CI]: 1.70, 4.13) was linked to a higher chance of stopping PCA use. Having hypertension (aOR: 0.46, 95% CI: 0.26, 0.81) and being classified as the American Society of Anesthesiologists class 3 or higher (aOR: 0.48, 95% CI: 0.23, 0.86) were associated with a lower chance of discontinuing PCA use.

CONCLUSION

Our study determined the risk factors to stop using IV PCA due to side effects following lung or esophageal surgery. These results emphasize the need for personalized pain management plans that take into account the patient's characteristics and the type of surgery performed.

Temporal dynamics of interoceptive attention and positive and negative affect in adults engaging in disordered eating and nonsuicidal self-injury

OBJECTIVE

Interoception (the sense of the body's state) is associated with eating disorders and nonsuicidal self-injury, potentially through relationships with affect. We examined the relationship between interoceptive attention and both positive and negative affect.

METHODS

Participants (N = 128) who reported recent self-harm (i.e., disordered eating and/or non-suicidal self-injury) completed ecological momentary assessment for 16 days. Participants completed multiple daily assessments of affect and interoceptive attention. We then tested the temporal dynamic relationship between interoceptive attention and affect.

RESULTS

There was a relationship between positive affect and interoceptive attention such that people with higher average positive affect, and times when people were above their typical positive affect, were associated with higher interoceptive attention. There was a negative relationship between negative affect and interoceptive attention, such that people with higher average negative affect, and times when people were above their own typical negative affect, were associated with lower interoceptive attention.

CONCLUSIONS

Better mood may associate with greater willingness to attend to body sensations. Our findings support active inference models of interoception and highlight the importance of refining our understanding of the dynamic nature of interoception and its relationship with affect.

Randomized cross-over evaluation of investigator gender on pain thresholds in healthy volunteers

Background and aims: This randomized cross-over study in healthy volunteers was designed primarily to evaluate the potential impact of investigator gender on electrical pain threshold (EPT) and corresponding pain intensity levels, and secondly to evaluate potential differences in those interventions between female and male study participants. Methods: Forty adult volunteers (22 females) were included. An electrical stimulation device was used to determine EPT levels (in pain magnitude scores) in series of three in each study participant - once by a female, and once by a male investigator - according to a predefined cross-over design schedule. Corresponding levels of pain intensity were scored on a visual analog scale (VAS) slide ruler. Results: Study data was obtained and analysed in all participants. Significantly higher EPT levels were determined by the female investigator compared with the male investigator (median 22 (IQR 12-31) vs. 8 (6-10) pain magnitude scores; p<0.0001), despite similar levels of reported pain intensity (1.9 (1.2-3.0) vs. 2.0 (1.1-3.4) VAS units; p>0.300). There were no differences in EPT levels between female and male subjects evaluated by female (p>0.300) and male (p=0.125) investigators, or between the first and second series of stimulation (p>0.300). Conclusions: Our finding of significantly higher EPT levels when study participants of both genders - despite no difference in reported pain intensity - were evaluated by a female than by a male investigator, indicates a potential impact of investigator gender on the individual perception of pain. Implications: By contributing to a better understanding of how individual pain threshold levels are potentially influenced by investigator gender, this study might facilitate future evaluation of pain conditions in both preclinical and clinical settings.

Mental heartbeat tracking and rating of emotional pictures are not related

Our aim was to conceptually replicate the findings of previous empirical studies showing that people with higher cardiac interoceptive accuracy experience more intense emotions. Apart of the mental heartbeat tracking task of Schandry, Hungarian (n = 46, 76.0% female, mean age 22.28 ± 2.228) and Norwegian (n = 50, 60.0% female, mean age 24.66 ± 3.048) participants rated the arousal and valence evoked by positive, neutral and negative pictures. Multivariate repeated analysis of variance (applying both frequentist and Bayesian approaches) did not reveal any connection between heartbeat perception scores and the subjective ratings (i.e., arousal and valence) of the pictures in any of the two groups. The lack of the expected association between cardioceptive accuracy and arousal might partly be explained by the methodological differences between previous studies and this one; for example, we did not split or preselected the sample based on the performance on the Schandry task and applied a relatively strict instruction (i.e., by encouraging to count felt heartbeats only, and to report zero if no sensations were detected).