Multicentre prospective validation of use of the Canadian C-Spine Rule by triage nurses in the emergency department

Objectives

The Canadian C-Spine Rule for imaging of the cervical spine was developed for use by physicians. We believe that nurses in the emergency department could use this rule to clinically clear the cervical spine. We prospectively evaluated the accuracy, reliability and acceptability of the Canadian C-Spine Rule when used by nurses.

Methods

We conducted this three-year prospective cohort study in six Canadian emergency departments. The study involved adult trauma patients who were alert and whose condition was stable. We provided two hours of training to 191 triage nurses. The nurses then assessed patients using the Canadian C-Spine Rule, including determination of neck tenderness and range of motion, reapplied immobilization and completed a data form.

Results

Of the 3633 study patients, 42 (1.2%) had clinically important injuries of the cervical spine. The kappa value for interobserver assessments of 498 patients with the Canadian C-Spine Rule was 0.78. We calculated sensitivity of 100.0% (95% confidence interval [CI] 91.0%–100.0%) and specificity of 43.4% (95% CI 42.0%–45.0%) for the Canadian C-Spine Rule as interpreted by the investigators. The nurses classified patients with a sensitivity of 90.2% (95% CI 76.0%–95.0%) and a specificity of 43.9% (95% CI 42.0%–46.0%). Early in the study, nurses failed to identify four cases of injury, despite the presence of clear high-risk factors. None of these patients suffered sequelae, and after retraining there were no further missed cases. We estimated that for 40.7% of patients, the cervical spine could be cleared clinically by nurses. Nurses reported discomfort in applying the Canadian C-Spine Rule in only 4.8% of cases.

Conclusion

Use of the Canadian C-Spine Rule by nurses was accurate, reliable and clinically acceptable. Widespread implementation by nurses throughout Canada and elsewhere would diminish patient discomfort and improve patient flow in overcrowded emergency departments.Each year, Canadian emergency departments treat 1.3 million patients who have suffered blunt trauma from falls or motor vehicle collisions and who are at risk for injury of the cervical spine.¹ Most of these cases involve adults who are alert and in stable condition, and less than 1% involve fracture of the cervical spine.² Most trauma patients who have been transported in ambulances are protected by a backboard, collar and neck supports. Nurses are responsible for initial triage in the emergency department and usually send such patients to high-acuity resuscitation rooms, where they may remain fully immobilized for hours until assessment by a physician and radiography are complete. This prolonged immobilization is often unnecessary and adds considerably to patient discomfort. The delay also adds to the burden of overcrowded Canadian emergency departments in an era when they are under unprecedented pressures.^3–5 These patients occupy valuable space in resuscitation rooms, and repeated efforts to obtain satisfactory radiographs or computed tomography scans of the cervical spine use valuable time on the part of physicians, nurses and technicians.A clinical decision rule is defined as a decision-making tool incorporating three or more variables from the patient’s history, a physical examination or simple tests. Such rules are derived from original research and help clinicians with diagnostic or therapeutic decisions at the bedside. We previously developed a clinical decision rule for evaluation of the cervical spine.^6,7 The Canadian C-Spine Rule comprises simple clinical variables (Figure 1) and was designed to allow clinicians to “clear” immobilization of the cervical spine (i.e., remove neck collar and other devices) without radiography and to decrease immobilization times.⁸ We also validated the accuracy of the rule when used by physicians.⁹ We recently completed an implementation trial at 12 Canadian hospitals to evaluate the impact on patient care and outcomes of the Canadian C-Spine Rule when used by physicians.¹⁰Open in a separate windowFigure 1The Canadian C-Spine Rule to rule out cervical spine injury, adapted for use by nurses. The rule is intended for patients who have experienced trauma, who are alert (score on Glasgow Coma Scale = 15) and whose condition is stable. *The following mechanisms of injury were defined as dangerous: fall from elevation of more than 3 ft (91 cm) or five stairs, axial load to the head (e.g., diving injury), motor vehicle collision at high speed (> 100 km/h), motor vehicle collision involving a rollover or ejection, injury involving a motorized recreational vehicle, bicycle-related injury (rider struck or collision). †Simple rear-end motor vehicle collisions exclude incidents in which the patient was pushed into oncoming traffic or was hit by a bus, large truck or vehicle travelling at high speed, as well as rollovers; all such incidents would be considered high risk. ‡Neck pain with delayed onset is any pain that did not occur immediately following the precipitating incident. Adapted, with permission, from Stiell IG, Wells GA, Vandemheen K, et al. The Canadian Cervical Spine Radiography Rule for alert and stable trauma patients. JAMA 2001;286:1841–8.⁸ Copyright © 2001 American Medical Association. All rights reserved.Nurses in the emergency department usually do not evaluate the cervical spine of trauma patients, and they routinely send all immobilized patients to the emergency department’s resuscitation room. We believe that nurses could safely evaluate alert patients who have arrived by ambulance and whose condition is stable and could “clear” immobilization of the cervical spine of low-risk patients upon arrival at the triage station.¹¹ Patients could then be much more rapidly, comfortably and efficiently managed in other areas of the emergency department. An expanded decision-making role for nurses has the potential to improve the efficiency of trauma care in all Canadian hospitals. Very little research has been done to determine the ability of nurses to clear immobilization of the cervical spine.^12–15 Our objective in this study was to prospectively evaluate the accuracy, reliability and acceptability of the Canadian C-Spine Rule when used by nurses to assess patients’ need for immobilization.     

Changes in apparent free energy of helix-helix dimerization in a biological membrane due to point mutations

We present an implementation of the TOXCAT membrane protein self-association assay that measures the change in apparent free energy of transmembrane helix dimerization caused by point mutations. Quantifying the reporter gene expression from cells carrying wild-type and mutant constructs shows that single point mutations that disrupt dimerization of the transmembrane domain of glycophorin A reproducibly lower the TOXCAT signal more than 100-fold. Replicate cultures can show up to threefold changes in the level of expression of the membrane bound fusion construct, and correcting for these variations improves the precision of the calculated apparent free energy change. The remarkably good agreement between our TOXCAT apparent free energy scale and free energy differences from sedimentation equilibrium studies for point mutants of the glycophorin A transmembrane domain dimer indicate that sequence changes usually affect membrane helix-helix interactions quite similarly in these two very different environments. However, the effects of point mutations at threonine 87 suggest that intermonomer polar contacts by this side-chain contribute significantly to dimer stability in membranes but not in detergents. Our findings demonstrate that a comparison of quantitative measurements of helix-helix interactions in biological membranes and genuine thermodynamic data from biophysical measurements on purified proteins can elucidate how changes in the lipidic environment modulate membrane protein stability.     

p75 neurotrophin receptor regulates tissue fibrosis through inhibition of plasminogen activation via a PDE4/cAMP/PKA pathway

Clearance of fibrin through proteolytic degradation is a critical step of matrix remodeling that contributes to tissue repair in a variety of pathological conditions, such as stroke, atherosclerosis, and pulmonary disease. However, the molecular mechanisms that regulate fibrin deposition are not known. Here, we report that the p75 neurotrophin receptor (p75^NTR), a TNF receptor superfamily member up-regulated after tissue injury, blocks fibrinolysis by down-regulating the serine protease, tissue plasminogen activator (tPA), and up-regulating plasminogen activator inhibitor-1 (PAI-1). We have discovered a new mechanism in which phosphodiesterase PDE4A4/5 interacts with p75^NTR to enhance cAMP degradation. The p75^NTR-dependent down-regulation of cAMP results in a decrease in extracellular proteolytic activity. This mechanism is supported in vivo in p75^NTR-deficient mice, which show increased proteolysis after sciatic nerve injury and lung fibrosis. Our results reveal a novel pathogenic mechanism by which p75^NTR regulates degradation of cAMP and perpetuates scar formation after injury.     

Isolation and affinity maturation of hapten-specific antibodies

More and more recombinant antibodies specific for haptens such as drugs of abuse, dyes and pesticides are being isolated from antibody libraries. Thereby isolated antibodies tend to possess lower affinity than their parental, full-size counterparts, and therefore the isolation techniques must be optimized or the antibody genes must be affinity-matured in order to reach high affinities and specificities required for practical applications. Several strategies have been explored to obtain high-affinity recombinant antibodies from antibody libraries: At the selection level, biopanning optimization can be performed through elution with free hapten, analogue pre-incubation and subtractive panning. At the mutagenesis level, techniques such as random mutagenesis, bacterial mutator strains passaging, site-directed mutagenesis, mutational hotspots targeting, parsimonious mutagenesis, antibody shuffling (chain, DNA and staggered extension process) have been used with various degrees of success to affinity mature or modify hapten-specific antibodies. These techniques are reviewed, illustrated and compared.     

Murine macrophage P2X7 receptors support rapid prothrombotic responses

Non-apoptotic externalization of phosphatidylserine (PS) can act as a reactive surface for the efficient assembly of the prothrombinase complex leading to thrombin generation and coagulation. Here we show that extracellular ATP, acting at the macrophage P2X(7) receptor, drives the rapid Ca(2+)-dependent formation and release of PS-rich microvesicles that enhance the assembly of the prothrombinase complex and subsequent formation of thrombin. Incubation with P2X(7) receptor antagonists (KN-62 and Brilliant Blue G) attenuates ATP induced prothrombotic responses. Consistent with the hypothesis that exposed PS enhances prothrombinase activity; pre-incubation with annexin V blocks the increase in thrombin formation. The rapid translocation of PS and formation of pro-thrombotic microvesicles occurs in the absence of cell lysis. These data demonstrate that the pro-inflammatory P2X(7) receptor can also support and propagate rapid increases in thrombin formation.     

Caspase-mediated cleavage of the exosome subunit PM/Scl-75 during apoptosis

Recent studies have implicated the dying cell as a potential reservoir of modified autoantigens that might initiate and drive systemic autoimmunity in susceptible hosts. A number of subunits of the exosome, a complex of 3'→5' exoribonucleases that functions in a variety of cellular processes, are recognized by the so-called anti-PM/Scl autoantibodies, found predominantly in patients suffering from an overlap syndrome of myositis and scleroderma. Here we show that one of these subunits, PM/Scl-75, is cleaved during apoptosis. PM/Scl-75 cleavage is inhibited by several different caspase inhibitors. The analysis of PM/Scl-75 cleavage by recombinant caspase proteins shows that PM/Scl-75 is efficiently cleaved by caspase-1, to a smaller extent by caspase-8, and relatively inefficiently by caspase-3 and caspase-7. Cleavage of the PM/Scl-75 protein occurs in the C-terminal part of the protein at Asp369 (IILD³⁶⁹↓G), and at least a fraction of the resulting N-terminal fragments of PM/Scl-75 remains associated with the exosome. Finally, the implications of PM/Scl-75 cleavage for exosome function and the generation of anti-PM/Scl-75 autoantibodies are discussed.     

The atmospheric chemistry of trace gases and particulate matter emitted by different land uses in Borneo

We report measurements of atmospheric composition over a tropical rainforest and over a nearby oil palm plantation in Sabah, Borneo. The primary vegetation in each of the two landscapes emits very different amounts and kinds of volatile organic compounds (VOCs), resulting in distinctive VOC fingerprints in the atmospheric boundary layer for both landscapes. VOCs over the Borneo rainforest are dominated by isoprene and its oxidation products, with a significant additional contribution from monoterpenes. Rather than consuming the main atmospheric oxidant, OH, these high concentrations of VOCs appear to maintain OH, as has been observed previously over Amazonia. The boundary-layer characteristics and mixing ratios of VOCs observed over the Borneo rainforest are different to those measured previously over Amazonia. Compared with the Bornean rainforest, air over the oil palm plantation contains much more isoprene, monoterpenes are relatively less important, and the flower scent, estragole, is prominent. Concentrations of nitrogen oxides are greater above the agro-industrial oil palm landscape than over the rainforest, and this leads to changes in some secondary pollutant mixing ratios (but not, currently, differences in ozone). Secondary organic aerosol over both landscapes shows a significant contribution from isoprene. Primary biological aerosol dominates the super-micrometre aerosol over the rainforest and is likely to be sensitive to land-use change, since the fungal source of the bioaerosol is closely linked to above-ground biodiversity.     

Aging and factors related to running economy

The purpose of this study was to investigate the relationship that age has on factors affecting running economy (RE) in competitive distance runners. Fifty-one male and female subelite distance runners (Young [Y]: 18-39 years [n = 18]; Master [M]: 40-59 years [n = 22]; and Older [O]: 60-older [n = 11]) were measured for RE, step rate, lactate threshold (LT), VO2max, muscle strength and endurance, flexibility, power, and body composition. An RE test was conducted at 4 different velocities (161, 188, 215, and 241 m·min(-1)), with subjects running for 5 minutes at each velocity. The steady-state VO2max during the last minute of each stage was recorded and plotted vs. speed, and a regression equation was formulated. A 1 × 3 analysis of variance revealed no differences in the slopes of the RE regression lines among age groups (y = 0.1827x - 0.2974; R2 = 0.9511 [Y]; y = 0.1988x - 1.0416; R2 = 0.9697 [M]; y = 0.1727x + 3.0252; R2 = 0.9618 [O]). The VO2max was significantly lower in the O group compared to in the Y and M groups (Y = 64.1 ± 3.2; M = 56.8 ± 2.7; O = 44.4 ± 1.7 mlO2·kg(-1)·min(-1)). The maximal heart rate and velocity @ LT were significantly different among all age groups (Y = 197 ± 4; M = 183 ± 2; O = 170 ± 6 b·min(-1) and Y = 289.7 ± 27.0; M = 251.5 ± 32.9; O = 212.3 ± 24.6 m·min(-1), respectively). The VO2max @ LT was significantly lower in the O group compared to in the Y and M groups (Y = 50.3 ± 2.0; M = 48.8 ± 2.9; O = 34.9 ± 3.2 mlO2·kg(-1)·min(-1)). The O group was significantly lower than in the Y and M groups in flexibility, power, and upper body strength. Multiple regression analyses showed that strength and power were significantly related to running velocity. The results from this cross-sectional analysis suggest that age-related declines in running performance are associated with declines in maximal and submaximal cardiorespiratory variables and declines in strength and power, not because of declines in running economy.