Experimental comparison of dyspnea and pain

Pain and dyspnea control during awake fiberoptic bronchoscopy in critically ill patients: safety and efficacy of remifentanil target-controlled infusion

Purpose

Flexible fiberoptic bronchoscopy is frequently used in intensive care unit, but is a source of discomfort, dyspnea and anxiety for patients. Our objective was to assess the feasibility and tolerance of a sedation using remifentanil target-controlled infusion, to perform fiberoptic bronchoscopy in awake ICU patients.

Materials, patients and methods

This monocentric, prospective observational study was conducted in awake patients requiring fiberoptic bronchoscopy. In accordance with usual practices in our center, remifentanil target-controlled infusion was used under close monitoring and adapted to the patient’s reactions. The primary objective was the rate of successful procedures without additional analgesia or anesthesia. The secondary objectives were clinical tolerance and the comfort of patients (graded from “very uncomfortable” to “very comfortable”) and operators (numeric scale from 0 to 10) during the procedure.

Results

From May 2014 to December 2015, 72 patients were included. Most of them (69%) were hypoxemic and admitted for acute respiratory failure. No additional medication was needed in 96% of the patients. No severe side-effects occurred. Seventy-eight percent of patients described the procedure as “comfortable or very comfortable”. Physicians rated their comfort with a median [IQR] score of 9 [8–10].

Conclusion

Remifentanil target-controlled infusion administered to perform awake fiberoptic bronchoscopy in critically ill patients is feasible without requirement of additional analgesics or sedative drugs. Clinical tolerance as well as patients’ and operators’ comfort were good to excellent. This technique could benefit patients’ experience.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00832-6.

The impact of therapeutic opioid agonists on driving-related psychomotor skills assessed by a driving simulator or an on-road driving task: A systematic review

BACKGROUND

Driving cessation is associated with poor health-related outcomes. People with chronic diseases are often prescribed long-term opioid agonists that have the potential to impair driving. Studies evaluating the impact of opioids on driving-related psychomotor skills report contradictory results likely due to heterogeneous designs, assessment tools and study populations. A better understanding of the effects of regular therapeutic opioid agonists on driving can help to inform the balance between individual's independence and community safety.

AIM

To identify the literature assessing the impact of regular therapeutic opioid agonists on driving-related psychomotor skills for people with chronic pain or chronic breathlessness.

DESIGN

Systematic review reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis statement; PROSPERO Registration CRD42017055909.

DATA SOURCES

Six electronic databases and grey literature were systematically searched up to January, 2017. Inclusion criteria were as follows: (1) empirical studies reporting data on driving simulation, on-the-road driving tasks or driving outcomes; (2) people with chronic pain or chronic breathlessness; and (3) taking regular therapeutic opioid agonists. Critical appraisal used the National Institutes of Health's quality assessment tools.

RESULTS

From 3809 records screened, three studies matched the inclusion criteria. All reported data on people with chronic non-malignant pain. No significant impact of regular therapeutic opioid agonists on people's driving-related psychomotor skills was reported. One study reported more intense pain significantly worsened driving performance.

CONCLUSION

This systematic review does not identify impaired simulated driving performance when people take regular therapeutic opioid agonists for symptom control, although more prospective studies are needed.

The presence of respiratory disorders in individuals with low back pain: A systematic review

BACKGROUND

Inspiratory muscles, such as the diaphragm, play a key role in both respiration and spinal control. Therefore, diaphragm dysfunctions are often related to low back pain (LBP). However, few is known on the association between the presence of LBP and the presence of respiratory disorders (RD).

OBJECTIVES

To perform a systematic review on the relation between RD and LBP.

STUDY DESIGN

Systematic review.

METHODS

Two reviewers searched on PubMed/MEDLINE for studies concerning LBP and RD, from 1950 up to January 2016. The search string consisted of the following key words: low back pain, dyspnea, respiratory problems, lung diseases, comorbidity, pulmonary disease, chronic obstructive, smoking, asthma, allergy, sinusitis, respiratory tract infection and hyperventilation. The aim was to evaluate a potential correlation, co-occurrence or causality between RD and LBP.

RESULTS

A total of 16 articles were included. A significant correlation between the presence of LBP and the presence of RD such as dyspnea, asthma, different forms of allergy, and respiratory infections was found. No correlation was found between Chronic Obstructive Pulmonary Disease (COPD) and LBP, and no articles were found on the correlation between hyperventilation and LBP.

CONCLUSIONS

This is the first study providing an overview of the literature on the relation between LBP and RD. Immunological, biomechanical, psychosocial and socio-economic factors might explain this correlation. Smoking is likely to contribute. Future studies must reveal the causative relationship.

LEVEL OF EVIDENCE

Therapy, level 2a.

Dyspnea and pain frequently co-occur among Medicare managed care recipients

RATIONALE

Experimental and neuroimaging studies have suggested strong associations between dyspnea and pain. The co-occurrence of these symptoms has not been examined in community samples.

OBJECTIVES

We sought to ascertain the co-occurrence of pain and dyspnea by self-report in a large cohort of Medicare recipients.

METHODS

We analyzed data from 266,000 Medicare Managed Care recipients surveyed in 2010 and 2012. Dyspnea was defined by aggregating three questions about shortness of breath (at rest, while walking one block, and while climbing stairs). Pain was measured by four questions about pain interference, chest pain, back pain, and arthritis pain. All measures were dichotomized as high or low/none. We calculated the co-occurrence of pain and dyspnea at baseline, and generated logistic regression models to find the adjusted relative risk (RR) of their co-occurrence, adjusting for patient-level factors and three potential medical causes of dyspnea (chronic obstructive pulmonary disease/emphysema/asthma, congestive heart failure, and obesity). We modeled the simultaneous development and the simultaneous resolution of dyspnea and pain between baseline and 2 years.

MEASUREMENTS AND MAIN RESULTS

Participants with dyspnea had considerably higher prevalence of pain than those without (64 vs. 18%). In fully adjusted models, participants with any of the types of pain were substantially more likely to report dyspnea than those without these types of pain (high pain interference: relative risk [RR], 1.99; 95% confidence interval [CI], 1.92-2.07; chest pain: RR, 2.11; 95% CI, 2.04-2.18; back pain: RR, 1.76; 95% CI, 1.71-1.82; and arthritis pain: RR, 1.49; 95% CI, 1.44-1.54). The relative risks of dyspnea developing or resolving at 2 years were greatly increased (RRs of 1.5 - 4) if pain also developed or resolved.

CONCLUSIONS

Pain and dyspnea commonly occurred, developed, and resolved together. Most older adults with dyspnea also reported pain. Medical conditions typically assumed to cause dyspnea did not account for this association. The most plausible explanation for the co-occurrence is physical deconditioning.

Reliability and validity of an arabic version of the dyspnea-12 questionnaire for Saudi nationals with chronic obstructive pulmonary disease

BACKGROUND:

Dyspnea is a distressing symptom experienced by people with chronic obstructive pulmonary disease (COPD). The dyspnea-12 (D-12) questionnaire comprises of 12 items and assesses the quality of this symptom, its severity and the emotional response. The original (English) version of the D-12 is reliable and valid for the measurement of dyspnea in pulmonary diseases.

AIM:

To translate the D-12 into Arabic and determine whether this version is reliable and valid in Saudi nationals with COPD.

METHODS:

The D-12 was translated into Arabic version and reviewed by an expert panel before being back-translated into English. The Arabic version was administered to five patients with COPD to test whether it was easily understood after which a final Arabic version was produced. Thereafter, 40 patients with COPD (aged 63 ΁ 9 years; 33 [82.5%] males; forced expiratory volume in one second (FEV ₁) 47 ΁ 16% predicted) completed the D-12, the COPD Assessment Test (CAT) and the Chronic Respiratory Disease Questionnaire (CRDQ). Lung function and 6-minute walk distance were also measured. The D-12 was re-administered two weeks later.

RESULTS:

The Arabic version of the D-12 demonstrated good reliability over the two administration (intraclass correlation coefficient = 0.94, P = 0.01). Strong associations were demonstrated between the (1) total score for the D-12 and the CAT, (2) quality sub-score of the D-12 and the CAT and (3) emotional response sub-score of the D-12 and emotional function domain of the CRDQ (r ≥ 0.6, all P < 0.01).

CONCLUSION:

The Arabic version of the D-12 is a reliable and valid instrument in Saudi nationals with COPD.

Breathlessness--current and emerging mechanisms, measurement and management: a discussion from an European Association of Palliative Care workshop

BACKGROUND

A pre-conference workshop at the 2012 European Association of Palliative Care meeting discussed the current scientific and clinical aspects of breathlessness.

AIM

To describe a current overview of clinically relevant science in breathlessness.

DESIGN

A collation of workshop presentations and discussions.

DATA SOURCES

Narrative review.

RESULTS

The mismatch between the drive to breathe and the ability to breathe underlies the major theories of breathlessness unifying central processing of peripheral inputs including more recent recognition of the importance of peripheral muscles in mediating efferent inputs, supporting reduction of breathlessness with muscle conditioning. Key questions are whether there is a 'final common pathway' for breathlessness? Are the central nervous system targets for reducing breathlessness identical irrespective of underlying aetiology? Central nervous system functional imaging confirms an ability to differentiate severity (intensity) from affective components (unpleasantness). Breathlessness generates suffering across the community for patients and their caregivers often for long periods. The exertional nature of breathlessness means that reduction rather than elimination of the symptom is the therapeutic goal. No single intervention is likely to relieve chronic refractory breathlessness, but interventions made up of several components may provide incremental relief. Having optimally treated any underlying reversible components, the resultant chronic refractory breathlessness can be treated with pharmacological, psychological and physical therapies to reduce the sensation and its impacts.

CONCLUSION

Ensuring optimal delivery of interventions for breathlessness, whose design is underpinned by improving the understanding in the aetiology and maintenance of breathlessness, is the subject of ongoing controlled clinical trials.

Neuromodulation and Palliative Medicine

The palliative care population is generally vulnerable to experiencing medication-induced adverse effects and drug–drug interactions. Neuromodulation may offer particular advantages over systemic medications in this population. Spinal cord stimulation and peripheral nerve stimulation have long been utilized in efforts to provide analgesia for various painful conditions. More recently, deep brain stimulation/motor cortex stimulation has anecdotally been utilized for certain intractable pain states. Although brain electrical stimulation has not been adequately trialed or in some cases even tried at all for management of a variety of symptoms, it is conceivable that in the future it may be a potential therapeutic option in efforts to palliate various severe refractory symptoms (eg, intractable pain, nausea, dyspnea, delirium).

Combining nitrous oxide with carbon dioxide decreases the time to loss of consciousness during euthanasia in mice--refinement of animal welfare?

Carbon dioxide (CO(2)) is the most commonly used euthanasia agent for rodents despite potentially causing pain and distress. Nitrous oxide is used in man to speed induction of anaesthesia with volatile anaesthetics, via a mechanism referred to as the "second gas" effect. We therefore evaluated the addition of Nitrous Oxide (N(2)O) to a rising CO(2) concentration could be used as a welfare refinement of the euthanasia process in mice, by shortening the duration of conscious exposure to CO2. Firstly, to assess the effect of N(2)O on the induction of anaesthesia in mice, 12 female C57Bl/6 mice were anaesthetized in a crossover protocol with the following combinations: Isoflurane (5%)+O(2) (95%); Isoflurane (5%)+N(2)O (75%)+O(2) (25%) and N(2)O (75%)+O(2) (25%) with a total flow rate of 3 l/min (into a 7 l induction chamber). The addition of N(2)O to isoflurane reduced the time to loss of the righting reflex by 17.6%. Secondly, 18 C57Bl/6 and 18 CD1 mice were individually euthanized by gradually filling the induction chamber with either: CO(2) (20% of the chamber volume.min-1); CO(2)+N(2)O (20 and 60% of the chamber volume.min(-1) respectively); or CO(2)+Nitrogen (N(2)) (20 and 60% of the chamber volume.min-1). Arterial partial pressure (P(a)) of O(2) and CO(2) were measured as well as blood pH and lactate. When compared to the gradually rising CO(2) euthanasia, addition of a high concentration of N(2)O to CO(2) lowered the time to loss of righting reflex by 10.3% (P<0.001), lead to a lower P(a)O(2) (12.55 ± 3.67 mmHg, P<0.001), a higher lactataemia (4.64 ± 1.04 mmol.l(-1), P = 0.026), without any behaviour indicative of distress. Nitrous oxide reduces the time of conscious exposure to gradually rising CO(2) during euthanasia and hence may reduce the duration of any stress or distress to which mice are exposed during euthanasia.

Update on the role of palliative oxygen

PURPOSE OF REVIEW

Breathlessness remains a frequent and burdensome symptom for individuals with life-limiting symptoms in both malignant and nonmalignant settings. As oxygen therapy is frequently given as part of the management of breathlessness and is associated with costs, treatment burden and potential dangers, it is timely to review the efficacy and appropriateness of palliative oxygen therapy.

RECENT FINDINGS

Despite the widespread use of oxygen therapy in clinical and community settings, data supporting this approach is sparse. The benefits of long-term oxygen therapy for severely hypoxaemic people with chronic obstructive pulmonary disease are proven; however, mounting evidence suggests that oxygen does not confer additional benefit over medical air for the relief of refractory breathlessness in people with mild or absent hypoxaemia.

SUMMARY

On the basis of the findings of this review, the routine use of palliative oxygen therapy without detailed assessment of pathogenesis and reversibility of symptoms cannot be justified. Promoting self-management strategies, such as cool airflow across the face, exercise and psychological support for patients and carers, should be considered before defaulting to oxygen therapy. If palliative oxygen therapy is considered for individuals with transient or mild hypoxaemia, a therapeutic trial should be conducted with clinical review after 3 days to assess the net clinical benefit and patient preference.

Dyspnoea and the brain

Chronic dyspnoea is a devastating symptom that debilitates millions of people worldwide. It causes a large burden on both patient and carer, and significant costs to society and health services. Treatment options are limited. Much effort has been directed at optimising lung function and improving exercise capacity, however, the brain mechanisms underlying dyspnoea perception have received less attention. In this review, we focus on cognitive and affective aspects of dyspnoea and discuss how novel neuroimaging methods can provide quantitative measures of these subjective sensations. We draw parallels with the more advanced field of chronic pain, and explain some of the challenges faced when imaging dyspnoea. To date, brain mechanisms of dyspnoea have been investigated in a handful of studies by a limited number of authors. These have found consistent activation in the insular cortex, the anterior cingulate cortex and the amygdala. Novel neuroimaging methods and an improved understanding of perceptual mechanisms underlying dyspnoea now position us to transform dyspnoea research. Future research should investigate how brain regions associated with dyspnoea interact, as well as accurately correlate this neuronal activation with reliable behavioural measures. A better understanding of the brain processes underlying dyspnoea perception will lead to new therapies that will improve quality of life for a very large group of patients.

Additional evidence for the affective dimension of dyspnea in patients with COPD

The primary purpose of this secondary analysis was to determine whether 103 participants with chronic obstructive pulmonary disease rated the affective dimension of dyspnea (dyspnea-related anxiety and dyspnea-related distress) separately from the sensory dimension (intensity) during baseline exercise testing conducted as part of a randomized clinical trial. A secondary purpose was to determine if dyspnea-related anxiety and distress were rated distinctly different from other measurements of anxiety. At the end of a 6-minute walk and an incremental treadmill test, participant ratings of the magnitude of dyspnea-related anxiety and distress on the Modified Borg Scale were significantly different from their ratings of the intensity of dyspnea. Dyspnea-related anxiety and distress also appeared to be concepts independent from measures of state anxiety, negative affect, and anxiety before a treadmill test.

Reduced perception of dyspnea and pain after right insular cortex lesions

RATIONALE

The perception of dyspnea and pain show many similarities. Initial imaging studies suggested an important role of the insular cortex for the perception of both sensations. However, little is known about the cortical processing of dyspnea.

OBJECTIVES

This study investigated the influence of lesions of the insular cortex on the perception of dyspnea and pain.

METHODS

Dyspnea was induced by resistive loaded breathing in four patients with right-hemispheric insular cortex lesions, as assessed with computer tomography or magnetic resonance imaging, and four matched healthy control subjects. Pain was induced by a cold-pressor test. Perceived intensity and unpleasantness of both sensations were rated on visual analog scales.

MEASUREMENTS AND MAIN RESULTS

In contrast to healthy control subjects, patients with lesions demonstrated reduced perceptual sensitivity for dyspnea, in particular for the unpleasantness of dyspnea (P < 0.05). This was paralleled by reduced sensitivity for pain in patients with lesions, as reflected by smaller ratings of intensity and unpleasantness, higher sensory pain-thresholds, and, in particular, higher affect-related pain tolerance times (P < 0.05).

CONCLUSIONS

The results suggest that lesions of the right insular cortex are associated with reduced sensitivity for the perception of dyspnea and pain, in particular for their perceived unpleasantness. This underlines the importance of the insular cortex for the perception of both sensations.

Attentional distraction reduces the affective but not the sensory dimension of perceived dyspnea

The perception of dyspnea shows many similarities to the perception of pain. Both are multidimensional processes, which are not only influenced by sensory input but also by nonsensory factors like attention. Recent research has suggested that attentional distraction might reduce the perception of dyspnea but results are conflicting. Furthermore, the specific impact of attentional distraction on the distinct dimensions of perceived dyspnea has not been studied yet. Therefore, the present study examined the specific impact of changes in the attentional focus on the sensory and affective dimension of perceived dyspnea. Dyspnea was induced in forty-four healthy volunteers (mean age: 27.7 years, range: 18-47 years) by breathing through an inspiratory resistive load (3.57 kPa/L/s), while attention was directed either to breathing or distracted by reading texts. Inspiratory time (T(i)) and breathing frequency (f) were measured continuously. After each condition the experienced intensity (i.e., sensory dimension) and unpleasantness (i.e., affective dimension) of dyspnea were rated on separate visual analog scales (VAS), presented in randomized order. ANOVAs showed that attentional distraction during loaded breathing reduced the perceived unpleasantness of dyspnea (P<0.05), while the perceived intensity of dyspnea as well as T(i) and f remained unchanged. The results show that attentional distraction reduces the affective, but not the sensory dimension of induced dyspnea in healthy volunteers. Future studies are needed to clarify whether attentional distraction can effectively be used as intervention technique for reducing the unpleasant aspects of dyspnea in different patients groups.

Psychological aspects in the perception of dyspnea in obstructive pulmonary diseases

Dyspnea is an impairing symptom in obstructive pulmonary diseases. Besides multiple physiological pathways contributing to this sensation recent research has demonstrated an important role of psychological factors in the perception of dyspnea. The present review article synthesizes the research literature with regard to psychological aspects of the perception of dyspnea as well as other dyspnea-related issues such as course of disease, neuropsychological correlates and interventions that focus on psychological or behavioural changes. The available data show that inaccurate perception of dyspnea is related to poorer treatment outcome in obstructive pulmonary diseases and is impacted upon by emotional, attentional and learning processes. Neuropsychological deficits might further contribute to this association. Different psychological and behavioural interventions might reduce comorbid psychological disorders and thus improve the perception of dyspnea. However, future research is clearly required to substantiate current findings.