Reduction of healthcare-associated infections in a long-term care brain injury ward by replacing regular linens with biocidal copper oxide impregnated linens.

BACKGROUND: Contaminated textiles in hospitals contribute to endogenous, indirect-contact, and aerosol transmission of nosocomial related pathogens. Copper oxide impregnated linens have wide-spectrum antimicrobial, antifungal, and antiviral properties. Our aim was to determine if replacing non-biocidal linens with biocidal copper oxide impregnated linens would reduce the rates of healthcare-associated infections (HAI) in a long-term care ward. METHODS: We compared the rates of HAI in two analogous patient cohorts in a head injury care ward over two 6-month parallel periods before (period A) and after (period B) replacing all the regular non-biocidal linens and personnel uniforms with copper oxide impregnated biocidal products. RESULTS: During period B, in comparison to period A, there was a 24% reduction in the HAI per 1000 hospitalization-days (p<0.05), a 47% reduction in the number of fever days (>38.5°C) per 1000 hospitalization-days (p<0.01), and a 32.8% reduction in total number of days of antibiotic administration per 1000 hospitalization-days (p<0.0001). Accordingly there was saving of approximately 27% in costs of antibiotics, HAI-related treatments, X-rays, disposables, labor, and laundry, expenses during period B. CONCLUSIONS: The use of biocidal copper oxide impregnated textiles in a long-term care ward may significantly reduce HAI, fever, antibiotic consumption, and related treatment costs.

Atypical central pain processing in sensory modulation disorder: absence of temporal summation and higher after-sensation.

Sensory over-responsivity (SOR), a subtype of the proposed sensory modulation disorder (SMD), is characterized by over-responsiveness to stimuli in several sensory modalities. SMD individuals demonstrate abnormal responses to naturally occurring stimuli in a manner that interferes with daily life participation. Previous psychophysical testing of the somatosensory system revealed that SOR individuals rated pain sensations higher than controls, demonstrating hyperalgesia that can be centrally mediated. Temporal summation (TS) of second pain and after-sensation are manifestations of central sensitization; therefore, this study explored these measures for better characterization of central pain processing in SOR. Twelve SOR adults and 12 healthy controls participated. TS was produced by a train of fifteen repetitive heat pulses, 0.7 s duration each, and 2 s of inter-stimulus interval, applied to the thenar-eminence, while four pain ratings were obtained. An after-sensation was then measured for 5 min, obtaining six pain ratings. No TS of pain was indicated in the SOR group (SOR: p = 0.36; control: p < 0.001). Further, while controls reported a gradual disappearance of pain after-sensation, individuals with SOR continued to report pain for the duration of the 5 min measured (p = 0.002). These results demonstrate an atypical response pattern, suggesting alteration in pain processing and/or modulation at a central level in individuals with SOR. These possible neural changes may manifest themselves as interference with daily functioning as well as shed light on some of the between-subject variability seen in psychophysical testing in non-painful subjects.

Reproducibility of heart rate variability during rest, paced breathing and light-to-moderate intense exercise in patients one month after stroke.

AIM: To examine test-retest reliability of time and frequency domain heart rate variability (HRV) in patients 1 month after stroke during rest, paced breathing and light-to-moderate physical activity. METHODS: Fifteen patients up to 1 month after stroke underwent two measurements of HRV, with the measurements 4 days apart. Measurements took place under three conditions while sitting: (1) at rest with self-select breathing frequency, (2) paced breathing and (3) cycling while sitting. Reliability was assessed statistically by calculating intraclass correlation coefficients (ICC), standard error of measurement and coefficient of variance (CV). RESULTS: The relative reliability was found to be good-to-excellent for SDNN (ICC: 0.86-0.91), RMSSD (ICC: 0.81-0.87) and HF (ICC: 0.91-0.94) in all three conditions and poor for LF at rest and paced breathing (ICC: 0.43-0.47). The absolute reliability for all measures was found to be poor (CV >15%). CONCLUSIONS: HRV can be reliably assessed at rest, paced breathing and light-to-moderate physical activity for identifying differences between patients, while individual changes in autonomic functioning exhibited large random variations between test-retest measurements.

Correlation of intact sensibility and neuropathic pain-related behaviors in eight inbred and outbred rat strains and selection lines.

In some rat strains, total hindpaw denervation triggers autotomy, a behavior of self mutilation presumably related to neuropathic pain. Partial sciatic ligation (PSL) in rats produces tactile allodynia and heat hyperalgesia but not autotomy. Our aims in this study were to examine: (1) whether sensibility of intact rats to noxious and non-noxious stimuli is strain-dependent; (2) whether sensibility of intact rats could predict levels of autotomy, or of allodynia and hyperalgesia in the PSL model; and (3) whether autotomy levels are correlated with levels of allodynia or hyperalgesia. Here we report that in two inbred rat strains (Lewis and Fisher 344), two outbred rat strains (Sabra and Sprague-Dawley) and four selection lines of rats (Genetically Epilepsy-Prone Rats, High Autotomy, Low Autotomy and Flinders Sensitive Line), tactile sensitivity and response duration to noxious heat of intact animals were strain-dependent. Levels of autotomy following hindpaw denervation and of allodynia and hyperalgesia in the PSL model were also strain-dependent. Thus, these traits are determined in part by genetic factors. Sensory sensibility of intact rats was not correlated with levels of autotomy following total denervation, or allodynia and hyperalgesia following partial denervation. We suggest that preoperative sensibility of intact rats is not a predictor of levels of neuropathic disorders following nerve injury. Likewise, no correlation was found between autotomy, allodynia and hyperalgesia, suggesting that neuropathic pain behaviors triggered by nerve injury of different etiologies are mediated by differing mechanisms.

Preoperative open field behavior predicts levels of neuropathic pain-related behavior in mice.

Exploratory open field (OF) activity was assessed in seven different mouse strains and selection lines. We counted the number of beam interruptions made by three cagemate mice at a time. This assay tests reactivity to aversive stimuli, anxiety and emotionality. One hindlimb was then totally denervated by transecting the sciatic and saphenous nerves on one side, and autotomy, a behavior thought to be related to neuropathic pain, was quantified over 35 days. We report that OF activity and autotomy are highly variable across different strains/lines. These results reaffirm the genetic control of these behaviors. We also found that these behaviors are inversely and significantly correlated. We suggest that common genetically-determined neural mechanisms may underlie anxiety, emotionality and neuropathic pain in mice.

Experimental pressure pain in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy).

Research in animals shows that the levels of neuropathic pain expression is genetically associated with a characteristic response profile to sensory stimuli. The aim of the present investigation was to examine if pressure algometry can identify a specific pain sensitivity profile in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), and to distinguish complex regional pain syndromes from other chronic pain dysfunction syndromes. Pressure pain threshold and pain tolerance measured at the sternum in 17 patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), were compared with values obtained in 13 patients suffering from other chronic pain dysfunction syndromes and in a control group of 24 pain-free volunteers. The pressure algometer consisted of a force displacement transducer with a 0.25 cm2 tip connected to a recorder. The rate of force application was 1 kg/0.25 cm2/s. The difference between threshold and tolerance was defined as the pain sensitivity range. Young patients with complex regional pain syndrome (<40 yr) demonstrated a significantly higher mean pain sensitivity range compared with young subjects who had chronic pain or who were pain-free. Mean threshold and tolerance values were significantly lower in patients with complex regional pain syndrome (2.7+/-1.0 kg (mean +/- standard deviation) and 5.4+/-2.0 kg, respectively) and in patients suffering from other chronic pain syndromes (2.6+/-1.1 and 4.6+/-1.7 kg) than in healthy subjects (5.4+/-2.3 and 8.4+/-2.6 kg). Women in the chronic pain group exhibited a significantly lower pressure pain threshold than all other subgroups. Regardless of group, women exhibited lower pressure pain tolerance than men. In conclusion, the study contained herein shows a specific pain sensitivity profile to experimental stimuli behavior in young patients with complex regional pain syndrome expressed by a large pressure pain sensitivity range, at a location away from the painful area. However, one single pressure pain measurement over the sternum is insufficient for differentiation of patients with complex regional pain syndrome from those with chronic pain because of intersubject variation.

Brief electrical stimulation of c-fibers in rats produces thermal hyperalgesia lasting weeks.

Nerve injury produces neuropathic pain in some humans, but the nature of the signal triggering the pain is still unknown. When injured, many afferent fibers emit a prolonged discharge of action potentials. This input triggers pain disorders in rats following some, but not other types of total and partial nerve injury. In the present study we report that similar sensory disorders develop in rats by electrically stimulating an intact sciatic nerve. Robust thermal hyperalgesia and weak mechanical allodynia developed rapidly, lasting 3-5 weeks thereafter, but only when activating C-fibers. Thus, a discharge mimicking injury discharge in C-fibers, in the absence of any intended damage to the stimulated nerve, is sufficient to alter chronically central processing of sensory input.

Differential sensory-motor effects of pentobarbital in intact rats genetically selected for high vs. low neuropathic pain-related behaviour.

Denervation of the hindpaw in rodents triggers autotomy, a behaviour of licking, scratching and self-mutilation of the denervated paw. This behaviour has been used as a model of paraesthesia, dysaesthesia and neuropathic pain. HA and LA rats are lines that have been genetically selected for high or low levels of autotomy, respectively. Compared to intact LA rats, HA rats are more sensitive to convulsions induced by pentylenetetrazol (PTZ), a blocker of the chloride channel associated with the GABA(A) receptor. Here we tested whether an acute administration of a sedative but not anaesthetic dose of pentobarbital (PB) would differentiate between these rat lines, in a number of sensory and motor tests performed in intact rats. This drug was tested since in contrast to PTZ, PB enhances central nervous system (CNS) inhibition by increasing chloride flux through the same channel. We found that PB was significantly more ataxic, antinociceptive, and reduced touch sensitivity in LA rats, compared to HA rats. These results suggest that HA and LA rats genetically differ in the levels of central inhibitions mediated by the GABA system presumably at the chloride channel. This difference may be associated with the dichotomous expression of neuropathic pain in these rat lines.

A novel computerized system for analyzing motor and social behavior in groups of animals.

We present here the VMB Tracking System, a novel method for tracking locomotor activity, posture, thigmotactic scanning behavior and social interactions of up to eight animals at a time, at a high resolution (up to+/-0.1 mm). We used a commercially available computerized system that is considerably cheaper than other available methods. This system utilizes a basic personal computer controlling three transponders ('towers') fixed in space above the tested area, where animals as small as rats stroll freely in their normal habitat or in an experimental arena. Each tower emits infra-red (IR) pulses to a transponder ('button') adhered to a plastic mount glued to a shaved area of skin on the animal's back. When the button detects the IR pulses it responds with a button-specific ultrasonic signal that is fed back to the towers. The 3D location of the buttons is calculated by triangulation. Movement parameters of each button, such as displacement trajectory, time, speed and acceleration, can be displayed on-line and stored for off-line analysis. This system can be used to track animals in any lighting conditions, and to assess drug effects on the CNS, neuromuscular junction or muscle. As an example we demonstrate the ataxic effects of pentobarbital in rats.

Behavior of F-response and determination of actively involved motoneurons.

Fifteen nerves were examined in 10 healthy subjects, using a collision technique with 2 stimulation pulses of different intensity on the same point. The F-waves which occurred after the antidromic activation of the motor neuron cells by the first supramaximal pulse were blocked on their return pathway by the collision with the depolarization induced by the second pulse. The progressive decrement of the voltage of the second stimulus allowed, the transmission of the recurrent discharge along motor fibers with a lower depolarization threshold. The amplitude and the persistence of the F-waves increased (p < 0.05 and p < 0.001 respectively), while their latency decreased (p < 0.01) concurrent with the liberation of additional motor neurons with a lower threshold of depolarization. These findings suggest that the F-wave may be elicited in motoneuron of different depolarization threshold but primarily in larger and faster nerve fibers, with a lower threshold of depolarization.

Assessment of pain threshold and pain tolerance in women in labour and in the early post-partum period by pressure algometry.

The changes in the pressure pain threshold (PPThr) and pressure pain tolerance (PPTol) in 41 parturients have been studied during the active phase of labour and in the early post-partum period. The sensitivity to pressure stimuli was examined with an electronic pressure algometer placed on the sternum during the interval between painful contractions, after extradural analgesia and 24 h after childbirth. Prior to extradural analgesia, mean (+/- SD), PPThr and PPTol were 4.9 +/- 1.6 kg 0.25 cm-2 and 6.9 +/- 1.8 kg 0.25 cm-2, respectively. Similar values were recorded 1 h after induction of the extradural block when the pain of labour was abolished. At 24 h post-delivery, a significant decrease in both PPThr and PPTol was noted (P < 0.001). The lack of influence of extradural analgesia on pressure algometry values, and the elevated sensitivity to pain in the early post-partum period, may be related to the influence of pregnancy and labour on the appreciation of pain.

Electronic pressure algometry of deep pain in healthy volunteers.

Deep pressure pain threshold (PPT) and pressure pain tolerance (PPtol) were measured by pressure algometry at the mastoid processes, external malleoli, and sternum in 24 healthy volunteers. The algometer consisted of a force displacement transducer with a 0.25 cm2 pressure tip linked to a recorder. The rate of force application was approximately 1kg/sec/0.25cm2. High intersubject variation was noted at all sites for both PPT and PPtol. Mean PPT and PPtol values at the sternum were 5.2kg +/- 2.1 and 8.1kg +/- 2.4, respectively, and significantly higher than at the other sites. PTT did not differ significantly between the sexes or between dominant and nondominant sides. PPtol, on the other hand, was lower in the women, but significantly so only at the malleoli. On repeat examination, comparison between the mean values at each site showed no statistical differences in any instance. Pressure algometry, as used in this study in healthy subjects, proved a reliable technique for the estimation of deep PPT and PPtol values. It may possibly serve for screening the response to experimental pain in various groups of pain patients.

Diagnostic value of computer analysis of multipeaked EMG spikes.

Computer analysis of absolute number of peaks per second and the number of peaks in the multipeaked spikes/sec was carried out in the EMG interference recordings of 5 healthy, 6 myopathic and 8 neuropathic subjects. The purpose of the study was to detect diagnostically different patterns. A spike was considered multipeaked if it had 6 or more peaks. The amplitude of elimination (baseline) was examined at 1: 5, 1: 10 and 1: 15 of the average amplitude per second. Both the number of peaks and the number of peaks in multipeaked spikes in the neuropathic and myopathic muscles showed statistically significant differences when compared to healthy muscles. This technique could give an indication for the differential diagnosis of myopathic, neuropathic or healthy state of the muscle.

Fourier series analysis of the electrophysiological pattern of fatigue in healthy human beings, after curare administration.

Real time computer analysis of the electrophysiological development of muscular fatigue after small doses of d-tubocurarine (TC), has been examined in anesthetized human beings. As compared to a decrease of frequency in the control measurements, previous studies have shown an increase of the frequency of spikes after TC administration. The present experiments were carried out on the biceps brachii of 8 healthy human volunteers maintained in isometric contraction against a constant counter load until complete fatigue occurred. The Fourier spectrum analysis showed a statistically significant shift to lower frequencies before, and a milder statistically non significant shift after TC. These results may indicate that under mild curarization the early phase of muscular contraction requires a higher number of large motor units and thus, at a later stage of the contraction the pool of available large motor units becomes smaller. This conclusion supports the hypothesis that mild curarization causes a state of initial muscular fatigue.

Comparison of the electrophysiological pattern of fatigue between athletes required to perform explosive and endurance sports.

The electrophysiological behavior of an isometric contraction sustained to fatigue, was examined in 6 long distance runners and 9 athletes involved in explosive (burst) sports, by on line computer analysis of the electrical activity of vastus medialis, rectus femoris and vastus lateralis. The experiments were carried out with a counterload of 50% of the maximal strength of the muscle. The duration of spike increased and the frequency decreased in the 3 examined muscles, in both types of sport. In the burst sports the changes of value of both parameters were statistically significant in the 3 muscles. In endurance sports the variations of duration were not significant and the changes of frequency were statistically significant only in the vastus lateralis. These results could be explained by the gradual activation of motor units of more strikingly different sizes in burst sports. Thus it may be speculated that prolonged training in burst sports may result in the automatic mobilization of higher number of small motor units, for the initiation of contraction while in endurance sports the onset of contraction is more gradual and carried out by large motor units.

Effect of filter setting on the electromyographic parameters of muscles contracting to fatigue.

The effects of various filter settings on the electrophysiological behavior of the development of muscular fatigue were studied. Eleven healthy volunteers were examined during isometric contraction of biceps brachii and rectus femoris against a constant load until fatigue occurred. The electrical activity was taped and computer processing was carried out at the basic setting of 15-5000 cycles and at low (15-200 Hz) and high (200-5000 Hz) frequence filter. The results support the hypothesis that in the low range of frequencies there is a high density of large slow motor units, while in the high range of frequencies there are numerous small fast motor units.

Proximal monomelic amyotrophy of the upper limb.

A 30-year-old patient of Central European origin, suffering from monomelic amyotrophy, is presented. The disease was characterized by proximal weakness of one upper limb, mainly of the shoulder girdle, accompanied by atrophy. The electrodiagnostic examination revealed signs of partial denervation in the presence of normal motor and sensory conduction. The disease, which is probably of the anterior horn cells, had a benign course and good prognosis, as evident from repeated examinations during a follow-up of eight years.