Christiane Manzini

Quality of sleep and its daily relationship to pain intensity in hospitalized adult burn patients.

&NA; Sleep disturbances are frequently reported in victims following burn injuries. This prospective study was designed to assess sleep quality and to examine its daily relationship to pain intensity within the first week of hospitalization. Twenty‐eight non‐ventilated patients were interviewed during 5 consecutive mornings (number of observations=140) to collect information about perceived quality of sleep (visual analogue scale, number of hours, number of awakenings, presence of nightmares). Pain intensity was assessed at rest (nighttime, morning, during the day) and following therapeutic procedures using a 0–10 numeric scale. Seventy‐five percent of patients reported sleep disturbances at some point during the study although, in most patients, sleep quality was not consistently poor. Pooled cross‐section regression analyses showed significant temporal relationships between quality of sleep and pain intensity such that a night of poor sleep was followed by a significantly more painful day. Pain during the day was not found to be a significant predictor of poor sleep on the following night. These results support previous findings that perceived quality of sleep following burn injury is poor. Moreover, they show a daily relationship between quality of sleep and acute burn pain in which poor sleep is linked to higher pain intensity during the day.

Quantitative Polygraphic Controlled Study on Efficacy and Safety of Oral Splint Devices in Tooth-grinding Subjects

The efficacy of occlusal splints in diminishing muscle activity and tooth-grinding damage remains controversial. The objective of this study was to compare the efficacy and safety of an occlusal splint (OS) vs. a palatal control device (PCD). Nine subjects with sleep bruxism (SB) participated in this randomized study. Sleep laboratory recordings were made on the second night to establish baseline data. Patients then wore each of the splints in the sleep laboratory for recording nights three and four, two weeks apart, according to a crossover design. A statistically significant reduction in the number of SB episodes per hour (decrease of 41%, p = 0.05) and SB bursts per hour (decrease of 40%, p < 0.05) was observed with the two devices. Both oral devices also showed 50% fewer episodes with grinding noise (p = 0.06). No difference was observed between the devices. Moreover, no changes in respiratory variables were observed. Both devices reduced muscle activity associated with SB.

Sleep arousal response to experimental thermal stimulation during sleep in human subjects free of pain and sleep problems

Abstract Although the interaction between sleep and pain is generating considerable interest (NIH Technology Assessment Panel, 1996), it is still unknown if chronic pain is the cause or effect of poor sleep. To further this understanding, subjects free of pain and sleep problems need to be studied in order to assess their response to pain during sleep, defined as a behavioral and a physiological state in which sensory processing is altered. (For example, while auditory perception remains active, other sensory inputs are facilitated, attenuated, or suppressed (Velluti, 1997)). The present study provides data on polygraphic responses to cool (24°C), warm (37°C), and heat pain (>46°C) stimuli applied to shoulder skin during different sleep stages: the lighter sleep stage 2, the deep stages 3&4, and REM sleep. Based on evidence from eight subjects, we found that nociceptive heat stimulation evokes a moderate level of cortical arousal during sleep. Specifically, in comparison to the response induced by a warm 37°C non‐nociceptive control stimulation, the percentage of cortical arousal responses to heat pain stimuli (>46°C) was statistically greater in the lighter sleep stage 2 (48.3%) than in the deeper stages 3&4 (27.9%). A nocifensive behavioral‐motor response was associated with only 2.5% of the 351 heat pain stimuli. Two other markers of sleep quality–sleep stage shift and awakening–were not influenced by the thermal stimuli. None of the subjects demonstrated any burns in the morning following the thermal stimulations applied during sleep. We conclude that the processing of nociceptive inputs is attenuated across sleep stages.

Experimental pain perception remains equally active over all sleep stages

&NA; The literature on sensory perception during sleep suggests that light sleep (Stage 2) is more responsive to external sensory stimulation (e.g. sound, electrical shock) than deep sleep (Stages 3 and 4) and REM sleep. The main objective of this study was to characterize the specificity of nociceptive stimulation to trigger sleep arousal–awakening over all sleep stages. Thirteen healthy adults (e.g. without pain or sleep problems; six female and seven male of a mean age of 24.2±1.3 years) were included in the study. The responses to noxious intramuscular 5% hypertonic infusion were compared to innocuous vibrotactile and to respective control stimulations: isotonic infusion and auditory stimulations. These stimulations were applied during wakefulness and were repeated during sleep. Polygraphic signals (e.g. brain activity, heart rate) signals were recorded to score sleep arousal over all sleep stages. A subjective assessment of sleep quality was made on next morning. No overnight sensitization or habituation occurred with any of the experimental stimulations. The vibratory–auditory stimulations and the noxious hypertonic infusions triggered significantly (P<0.05) more awakenings in sleep Stage 2 and in REM than their respective control stimulations. In sleep Stage 2, both vibratory+auditory stimulations and the noxious hypertonic infusions has the same awakening response frequency (≈30%), however, with the noxious infusions the response frequency were similar in sleep Stages 3 and 4 (P<0.05) and in REM (trend). Compared to the baseline night, sleep quality was lower following the night with noxious stimulation (90.1±2.7 and 73.3±7.4 mm, respectively; P<0.03). These data suggest that pain during sleep could trigger a sleep awaking response over all sleep stages and not only in light sleep.

Heart rate changes during sleep in response to experimental thermal (nociceptive) stimulations in healthy subjects

OBJECTIVE During wakefulness, nociceptive thermal stimulation can trigger a rapid and transient rise in heart rate (HR). During sleep, HR variations are different across sleep stages; HR is more variable in stage 2 and in REM than in stages 3 and 4. The aim of this study was to assess the HR response to experimental thermal stimulation during different sleep stages. METHODS Eight young subjects free of sleep and pain problems, underwent a night of polysomnographic recording during which experimental thermal stimulations were applied. During all sleep stages (St), a series of cold, warm/control and heat pain stimulations were applied over the shoulder skin by means of a water-driven system. Variation of HR interval was measured for 6 s before and for 6 s during the thermal stimulation. RESULTS In comparison to control warm stimulation, experimental nociceptive thermal stimulation induced a significant rise in HR during sleep; HR increased by 7% in St 2, 5.4% in St 3&4, and by 4.3% in REM sleep. CONCLUSION The brief increase in cardiac activity with experimental nociceptive stimulation suggests that during sleep, the autonomic-cardiac nervous system remains reactive to external sensory inputs and is part of the physiological response to preserve body safety and sleep integrity in the face of potentially harmful stimulation.

Does Sleep Differ Among Patients with Common Musculoskeletal Pain Disorders

Most patients with chronic musculoskeletal pain report poor-quality sleep. The impact of chronic pain on sleep can be described as a vicious circle with mutual deleterious influences between pain and sleep-associated symptoms. It is difficult, however, to extract quantitative or consistent and specific sleep variables (eg, total sleep time, slow-wave sleep, sleep stage duration) that characterize the pain-related disruption of sleep. Comorbidity (eg, fatigue; depression; anxiety, sleep, movement, or breathing disorders) often confounds the reading and interpretation of sleep traces. Furthermore, many other methodologic issues complicate our ability to generalize findings (low external validity) to first-line medicine. Because sleep alterations in common musculoskeletal pain are neither specific nor pathognomonic, the aim is to provide a critical overview of the current understanding of pain and sleep interaction, discussing evidence-based and empiric knowledge that should be considered in further research and clinical applications.

Comparison of ambulatory and polysomnographic recording of jaw muscle activity during sleep in normal subjects

Clinicians and investigators need a simple and reliable recording device to diagnose or monitor sleep bruxism (SB). The aim of this study was to compare recordings made with an ambulatory electromyographic telemetry recorder (TEL-EMG) with those made with standard sleep laboratory polysomnography with synchronised audio-visual recording (PSG-AV). Eight volunteer subjects without current history of tooth grinding spent one night in a sleep laboratory. Simultaneous bilateral masseter EMG recordings were made with a TEL-EMG and standard PSG. All types of oromotor activity and rhythmic masseter muscle activity (RMMA), typical of SB, were independently scored by two individuals. Correlation and intra-class coefficient (ICC) were estimated for scores on each system. The TEL-EMG was highly sensitive to detect RMMA (0·988), but with low positive predictive value (0·231) because of a high rate of oromotor activity detection (e.g. swallowing and scratching). Almost 72% of false-positive oromotor activity scored with the TEL-EMG occurred during the transient wake period of sleep. A non-significant correlation between recording systems was found (r = 0·49). Because of the high frequency of wake periods during sleep, ICC was low (0·47), and the removal of the influence of wake periods improved the detection reliability of the TEL-EMG (ICC = 0·88). The TEL-EMG is sensitive to detect RMMA in normal subjects. However, it obtained a high rate of false-positive detections because of the presence of frequent oromotor activities and transient wake periods of sleep. New algorithms are needed to improve the validity of TEL-EMG recordings.

Estimation of pain intensity in emergency medicine: a validation study.

&NA; This study was designed to estimate the validity of an 11‐point verbal numerical rating scale (VNRS) and a 100 Unit (U) plasticized visual analogue scale (VASp) using a 100 mm paper visual analogue scale (VAS) as a gold standard, to recommend the best method of reporting the intensity of acute pain in an emergency department (ED). A convenience sample of 1176 patients with acute pain were recruited in the ED of a teaching hospital. Patients >18 years and able to use the different scales were included. Scales were presented randomly. Results were converted to a 0–100 U scale and validity was quantified using the Bland–Altman method and the intra‐class correlation (ICC). The limits of acceptability were previously set for the limits of agreement at ±20 U, with a constant bias. The Bland–Altman method revealed a small bias of –4 U for the VNRS and +1 U for VASp. However, the bias of the VNRS varied with the intensity of pain from −10 to +1 U. The limits of agreement between the VNRS&VAS and the VASp&VAS were −25; +17 U and −17; +18 U, respectively. The ICC was excellent between the VNRS&VAS (0.88) and the VASp&VAS (0.92). In conclusion, the VASp has a small bias, acceptable limits of agreement and an excellent intra‐class correlation. It is probably a valid tool to estimate acute pain in the ED. However, the VNRS is less valid in that context because of its wide limits of agreement and variable bias (mainly in lower scores).

The simple query “Do you want more pain medication?” is not a reliable way to assess acute pain relief in patients in the emergency department

OBJECTIVE The management of acute pain constitutes an essential skill of emergency department (ED) physicians. However, the accurate assessment of pain intensity and relief represents a clinically challenging undertaking. Some studies have proposed to define effective pain relief as the patients refusal for additional analgesic administration. The aim of this study was to verify whether such a refusal is effectively indicative of pain relief. METHODS This prospective cohort study included ED patients who received single or multiple doses of pain medication for an acute pain problem. Patients were evaluated for pain relief using one Likert scale and two dichotomous questions: Is your pain relieved? and Do you want more analgesics? Non-relieved patients were further analysed using a checklist as to the reasons behind their refusal for supplemental pain medication. RESULTS We have recruited 378 adult patients with a mean age of 50.3 years (±19.1); 60% were women and had an initial mean pain level of 7.3 (±2.0) out of 10. We observed that 68 out of 244 patients who were adequately relieved from pain asked for more analgesics (28%), whereas 51 out of 134 patients who were not relieved from pain refused supplemental drugs (38%). Reasons for refusal included wanting to avoid side effects, feeling sufficiently relieved, and disliking the medications effects. CONCLUSION Over a third of ED patients in acute pain were not relieved but refused supplemental pain medication. Patients have reported legitimate reasons to decline further analgesics, and this refusal cannot be used as an indication of pain relief.

Subjective sleep quality and its etiology in the emergency department

OBJECTIVE Patient sleep quality has a significant impact on recovery. However, most hospital units do not provide an optimal environment for sleep and there are currently no data available on how well patients sleep during their emergency department stay. The main objective of this study was to assess the subjective quality of nighttime sleep and factors that affect sleep in the emergency department (ED). METHODS A prospective sample of patients aged 18 years and older who presented to the ED from July 2015 to October 2015 was investigated. All participants were on stretcher and slept at least one night in the ED. Participants were asked to complete a sleep questionnaire adapted to the ED environment on sleep quality and its potentially modifying factors. RESULTS A total of 235 patients participated in the study (mean age: 64±20 years, 51% women). Compared to the week at home prior to admission, subjective sleep quality was lower in the ED (p<0.001): almost half the participants took more than 30 minutes to fall asleep, and they reported waking up 3.5 times per night on average. Lower subjective sleep quality in the ED was associated with higher stress, noise, and pain, as well as with stretcher comfort and lower home sleep quality the week prior to admission. CONCLUSIONS Subjective sleep quality in the emergency department is not optimal, and is influenced by stress, noise, pain, and stretcher comfort, all potentially modifiable factors.