Mind the gap: training road users to use speed and distance when making gap-acceptance decisions

Accurate gap-acceptance decisions require individuals to take into account both the distance to and the speed of an oncoming vehicle. The aim of the present studies was to develop an intervention that could successfully teach road users to focus on speed as well as distance. Across three studies, participants judged whether it was safe to cross the road or not when an oncoming vehicle was approaching from different distances and at different speeds. Study 1 trialed two techniques ("standard feedback" versus "three-look") aimed at improving gap judgments. Standard feedback involved telling participants what the actual speed of a car was after they had made an estimate, whereas the three-look technique required participants to make timed and controlled head movements when scanning the road environment. Only standard feedback increased the participants' mean gap-acceptance accuracy (assessed using both verbal and behavioral response measures). Study 2 also trialed two techniques, the standard feedback intervention used in Study 1, and a "two-response" intervention in which participants judged whether the oncoming vehicle was traveling at an atypical or normal speed. Study 2 found the two-response intervention to be more promising than the standard feedback procedure. Finally, Study 3 used video footage of oncoming vehicles to train younger (18-27 years) and older (60-80 years) adults and found the two-response intervention to be successful at improving gap-acceptance accuracies for both age groups. However, the intervention also resulted in more conservative gap judgments from participants in the older population independent of improvements in accuracy.

Nicolau syndrome following intramuscular diclofenac administration: a case report

Nicolau syndrome (livedoid dermatitis) is a rare adverse reaction of a still largely unidentified pathogenesis at the site of intramuscular drug injection. The typical presentation is pain around the injection site soon after injection, followed by erythema, livedoid patch, haemorrhagic patch, and finally necrosis of skin, subcutaneous fat, and muscle tissue. The phenomenon has been related to the administration of a variety of drugs, including non-steroidal anti-inflammatory drugs, corticosteroids, and penicillin. We report a case of Nicolau syndrome following an intramuscular injection of diclofenac. The large ulceration over the right buttock was positive for Pseudomonas aeruginosa, and histology revealed subcutaneous fat necrosis and non-specific inflammation with no evidence of malignancy or vasculitis. The lesion required multiple debridements and a partial-thickness skin graft. Subcutaneous injection, rather than intramuscular injection, was found to be a determining factor in this case. Clinicians must be cautious in the use of proper injection procedures, including appropriate needle length, in order to minimise complications.

Linking retinotopic fMRI mapping and anatomical probability maps of human occipital areas V1 and V2

Using functional MRI, we characterized field sign maps of the occipital cortex and created three-dimensional maps of these areas. By averaging the individual maps into group maps, probability maps of functionally defined V1 or V2 were determined and compared to anatomical probability maps of Brodmann areas BA17 and BA18 derived from cytoarchitectonic analysis (Amunts, K., Malikovic, A., Mohlberg, H., Schormann, T., Zilles, K., 2000. Brodmann's areas 17 and 18 brought into stereotaxic space-where and how variable? NeuroImage 11, 66-84). Comparison of areas BA17/V1 and BA18/V2 revealed good agreement of the anatomical and functional probability maps. Taking into account that our functional stimulation (due to constraints of the visual angle of stimulation achievable in the MR scanner) only identified parts of V1 and V2, for statistical evaluation of the spatial correlation of V1 and BA17, or V2 and BA18, respectively, the a priori measure kappa was calculated testing the hypothesis that a region can only be part of functionally defined V1 or V2 if it is also in anatomically defined BA17 or BA18, respectively. kappa = 1 means the hypothesis is fully true, kappa = 0 means functionally and anatomically defined visual areas are independent. When applying this measure to the probability maps, kappa was equal to 0.84 for both V1/BA17 and V2/BA18. The data thus show a good correspondence of functionally and anatomically derived segregations of early visual processing areas and serve as a basis for employing anatomical probability maps of V1 and V2 in group analyses to characterize functional activations of early visual processing areas.

Relationship between nocturnal hypoxaemia, tachycardia and myocardial ischaemia after major abdominal surgery

BACKGROUND

Episodic hypoxaemia, cardiac arrhythmias, and myocardial ischaemia may be related after major abdominal surgery.

METHODS

We studied 52 patients on the second and third nights after major abdominal operations, using continuous pulse oximetry and Holter ECG. We recorded the amount of time spent with oxygen saturation values less than 90, 85, and 80% during the night, and noted episodes of hypoxaemia, tachycardia, bradycardia, and ST-segment changes.

RESULTS

In 87 study nights there were 2403 (individual range 1-229) episodes of hypoxaemia, 3509 (individual range 1-234) episodes of tachycardia, and 265 (individual range 1-73) episodes of ST segment deviation. Of the 52 patients, 50 had episodes of hypoxaemia and tachycardia, and 19 patients had one or more episodes of ST segment deviation. For 38% of the episodes of ST deviation, there was an episode of hypoxaemia at the same time and in 16% there was an episode of tachycardia. ST deviation was only noted in 4% of the episodes of hypoxaemia and in 1% of the episodes of tachycardia.

CONCLUSION

Episodes of hypoxaemia and tachycardia frequently occur together after surgery but are rarely associated with ST deviation. Hypoxaemia or tachycardia is often present at the same time as ST deviation occurs.

Clinicotopographical Correlation of Corticospinal Tract Stroke

Background- Small capsular strokes are difficult to assess with regard to the precise location and the extent of pyramidal tract damage with conventional brain imaging. Color-coded diffusion tensor imaging (CDTI) provides a means to visualize the course of the corticospinal tract within the white matter. In addition to T2-weighted MRI, diffusion-weighted MRI and CDTI were used to analyze the topographical patterns of small lacunar corticospinal tract strokes.

METHODS

We examined 15 patients with pyramidal tract strokes in the subacute phase (days 3 to 7). Lesions were identified on diffusion-weighted MRI and superimposed on CDTI images. The anatomic location and pattern of the lesion were visualized on CDTI with regard to the corticospinal tract and subsequently compared with the clinical presentation. In addition, infarct areas were evaluated with quantitative parameters: mean diffusivity and lattice anisotropy index of lesions were determined.

RESULTS

We identified 5 different patterns of corticospinal tract stroke falling into 2 clinical subgroups: (1) those with marked deficits and minor improvement (6/15) and (2) those with good recovery (9/15). Group 1 had long lesions centered in the pyramidal tract, involving the basal ganglia (anterior choroidal artery); group 2 lesions were very small and/or located anteriorly and medially (periventricular anterior choroidal artery territory; thalamogeniculate, tuberothalamic, and lateral striate branches). Lesions showed a significant increase of mean diffusivity and decrease of lattice anisotropy.

CONCLUSIONS

CDTI allows in vivo differentiation of distinct subcortical stroke subtypes. Improved anatomic definition of lesion localization using CDTI may help in better establishing the prognosis for patients after subcortical stroke.

Bilateral internal carotid artery dissection mimicking inflammatory demyelinating disease

BACKGROUND AND PURPOSE

Internal carotid artery (ICA) dissection (ICAD) may be extremely difficult to diagnose only on the basis of historical information and clinical signs, and even standard brain imaging (computed tomography [CT], T2-weighted magnetic resonance imaging [MRI]) may not be sufficient to delineate the underlying pathology clearly, as shown in this case.

METHODS

The clinical presentation and parenchymal lesion pattern on CT were suggestive of inflammatory demyelinating disease, and additional multiparametric MRI was performed.

RESULTS

Diffusion-weighted MRI, magnetic resonance angiography, and perfusion-weighted MRI revealed acute ischemic lesions, bilateral ICA obstruction, and bilateral hypoperfusion in the middle cerebral artery territories. Bilateral ICAD was confirmed by Doppler and duplex ultrasound, and anticoagulation therapy was initiated. A follow-up examination showed recanalization of the obstructed ICAs and the normalization of cerebral perfusion.

CONCLUSION

This case illustrates the importance of demonstrating the pathology and the value of multiparametric MRI techniques for the diagnosis and monitoring of ICAD and its hemodynamic consequences.

Effect of oxygen on postoperative cardiovascular response to exercise

OBJECTIVE

To evaluate the effect of supplemental oxygen on postoperative cardiovascular response to submaximal exercise.

DESIGN

Randomised, controlled study.

SETTING

University hospital, Denmark.

SUBJECTS

16 patients having major abdominal operations.

INTERVENTIONS

A submaximal exercise test (heart rate up to 120 min(-1)) done twice on the third day after operation. Patients were given either 100% oxygen (4 L min(-1)) or air (21% oxygen, 4 L min(-1)) 30 minutes before and during the test in randomised order. During the tests they were monitored with a Holter tape recorder and a pulse oximeter.

MAIN OUTCOME MEASURES

Heart rate during exercise.

RESULTS

At similar workloads there were significantly lower heart rates (median decrease 3 min(-1)) during exercise tests with oxygen compared with air (p < 0.05). Holter monitoring showed signs of myocardial ischaemia in 6 patients in relation to exercise testing, 4 of them related to both tests, 2 of them only when breathing air. Signs of myocardial ischaemia disappeared when the exercise ended.

CONCLUSION

During the late postoperative period supplementary oxygen reduced heart rate in response to exercise to the same degree as observed previously in non-surgical patients and surgical patients not taking exercise. These findings do not suggest that decreased peripheral tissue oxygenation is responsible for the impaired cardiovascular response to exercise in postoperative patients.

Continuous pulse oximetry in the general surgical ward: Nellcor N-200 versus Nellcor N-3000

New measurement principles in pulse oximetry have been introduced to decrease the incidence of false movement alarms. Experimental studies have shown that the new Nellcor Symphony N-3000 may reduce the incidence of false alarms when monitoring during different activities. We compared the Nellcor Symphony N-3000 with the Nellcor N-200 pulse oximeter, when monitoring patients in the general surgical ward. Twenty-two patients were monitored during unrestricted ward activities for a total of 275 h with a N-3000 and a N-200 pulse oximeter simultaneously. Data were analysed for lack of concordance between the two pulse oximeters with respect to frequency of registered hypoxaemic episodes and thus the amount of time spent in the alarm state. The median number of desaturation episodes with the N-200 was 18 (range 0-511) compared with four (range 0-476) with the N-3000 (p < 0.0001). The median number of drop-outs (loss of signal) was 13 (range 1-46) with the N-200 compared with nine (2-41) with the N-3000 (p = 0.06). The N-200 registered saturation values of 85% or below for 23% of the observation time compared with 6% of the observation time with the N-3000 pulse oximeter (p < 0.0001). The different working principles of the two generations of oximeters were reflected in the present results derived from a clinical setting. The Nellcor Symphony N-3000 may offer an advantage compared with the Nellcor N-200, because of the reduced frequency of alarms and total time in alarm when monitoring patients in the general surgical ward.

Effect of oxygen treatment on heart rate after abdominal surgery

BACKGROUND

Cardiac complications are common during the postoperative period and may be associated with hypoxemia and tachycardia. Preliminary studies in high-risk patients after operation have shown a possible beneficial effect of oxygen therapy on arterial oxygen saturation and heart rate.

METHODS

The authors studied the effect of oxygen therapy on arterial oxygen saturation and heart rate in 100 consecutive unselected patients randomly and double blindly allocated to receive air or oxygen therapy between the first and fourth day after major abdominal surgery.

RESULTS

The median arterial oxygen saturation rate increased significantly from 96% to 99% (P < 0.0001) and the heart rate decreased significantly from 85 beats/min to 81 beats/min (P < 0.0001) during oxygen supplementation compared with air administered by a binasal catheter. The greatest decrease in heart rate occurred in patients with the lowest oxygen saturation or the highest heart rate values before oxygen supplementation. Overall, 73% of this unselected group of patients responded with decreased heart rate during supplemental oxygen therapy. No significant differences in changes in heart rate after oxygen supplementation were found between patients with or without an epidural catheter or between the postoperative day studied.

CONCLUSION

Postoperative oxygen therapy increased arterial oxygen saturation and decreased heart rate after uncomplicated abdominal surgery in a consecutive unselected group of patients who received routine postoperative care.

[Lung physiotherapy as prophylaxis against atelectasis and pneumonia after abdominal surgery]

Postoperative pulmonary complications play a significant role for the postoperative morbidity after abdominal surgery. To prevent this, an array of methods, such as lung physiotherapy, incentive spirometry, or mask treatment with positive airway pressure are used. The available controlled studies indicate that none of these treatment modalities reduce the occurrence of postoperative atelectasis, but only lung physiotherapy is able to reduce the development of postoperative pneumonia. Thus, we recommend lung physiotherapy as prophylactic treatment after abdominal surgery. The value of optimized pain alleviation and mobilisation in addition to lung physiotherapy should be evaluated in future trials.

Comparison of the Nellcor N-200 and N-3000 pulse oximeters during simulated postoperative activities

Twenty-six healthy volunteers were monitored simultaneously with the Nellcor N-200 and N-3000 pulse oximeters during nonhypoxaemic simulated postoperative activity. The overall number of registered events (hypoxaemic episodes or loss of signal) was fewer with the N-3000 than with the N-200 (8 vs. 32, p < 0.00005). Episodes of "desaturation' of > or = 5% from baseline were significantly fewer with the N-3000 than with the N-200 (5 vs. 19, p = 0.0001), and lowest values below 90% occurred nine times on the N-200, but were not seen with the N-3000 (p < 0.00005). Furthermore, episodes owing to loss of signal were significantly rarer with the N-3000 than with the N-200 (3 vs. 13, p = 0.001). The Nellcor N-3000 oximeter may offer an advantage over the N-200 model when monitoring patients in the postoperative period.

Alternative mRNA splicing of the novel GTPase Rab28 generates isoforms with different C-termini

A novel ras-related gene (rab28) was identified by a PCR-based cloning approach and subsequent screening of rat fat cell and brain cDNA libraries. The deduced amino acid sequence of the cDNA is distantly related with members of the Rab family (31-33% sequence identity, mainly restricted to the six GTP-binding motifs). Cloning of the human homologue of Rab28 by a PCR-based approach revealed the existence of two isoforms (hRab28S, hRab28L) which differ only by a 95-bp insertion within the coding region. This insertion generates an alternative sequence of the 30 C-terminal amino acids of the protein. Both C-termini of the human homologues comprise farnesylation motifs, but differ strikingly in a stretch of 13 amino acids. By PCR, mRNA of hRab28S was detected in most tissues investigated (cortex, liver, kidney, skeletal muscle, adipose tissue, testis and urothelium), whereas hRab28L was predominant in testis. Recombinant Rab28 proteins showed specific binding of radiolabeled guanosine 5'-O-[gamma-thio]triphosphate and rapidly hydrolysed [alpha-32P]GTP; there was no difference in the GTP binding characteristics of the two isoforms hRab28S and hRab28L. It is suggested that the isoforms are derived from the same gene by alternative mRNA splicing, and that their functions differ in a parameter unrelated to its basic role as a GTPase.

Impact of large-dose vitamin A supplementation on childhood diarrhoea, respiratory disease and growth

One hundred and seventy-two 0.5-3.0-year-old children in a mountainous area of northern Hebei Province of China were randomly assigned to a vitamin A supplementation group (n = 98) or a control group (n = 74) for a 1 year double-blind study. Capsules containing 200,000 IU vitamin A and 40 IU vitamin E were given to the children in the experimental group 3 and 9 months after baseline examination. During the 12 month study period, there was a significant reduction in the incidence of diarrhoea (P < 0.01) and respiratory disease (P < 0.01) in the children of the experimental group compared to the control. Risk of diarrhoea and respiratory disease were respectively 2.5 and 3.4 times higher in the control children. Serum retinol and IgA levels of the treatment group were significantly higher than that of control group (P < 0.01) 7 weeks after first supplementation. There was no significant difference in saliva IgA level between groups. No significant differences in growth were observed. It was concluded that supplementation with large doses of vitamin A decreased the incidence and severity of diarrhoea and respiratory disease in these children, possibly through enhanced activity of the immune system, but had no effect on growth over 1 year.