Objective: To evaluate the utility of a modified calculation of the alveolar dead space fraction (Vd/Vt), combined with plasma D-dimers, to aid in the exclusion of acute pulmonary embolism (PE). Methods: A prospective comparison of screening modalities was performed in a metropolitan teaching ED. Ambulatory patients evaluated for PE underwent simultaneous end-tidal CO, and arterial blood gas determinations, as well as venous latex-agglutination D-dimer quantification. The modified Bohr equation was used to calculate Vd/Vt as an index of alveolar dead space. Acute PE was diagnosed or excluded using appropriate combinations of clinical suspicion, ventilation-perfusion lung scanning, lower-extremity venous Doppler ultrasonography, pulmonary angiography, and comprehensive follow-up. Results: Of 170 subjects studied, PE was confirmed (PE+) in 26 (15%) and excluded (PE-) in 144 (85%). In the PE+ group, Vd/Vt was 0.31 & 0.13 (mean 2 SD), and in the PE-group, Vd/Vt was 0.06 t-0.10 (p c 0.05, t-test). Regarding false-negative rates, Vd/Vt was normal (i.e., c0.2) in 3/26 PE+ patients and D-dimer concentrations were normal (~0 . 5 pg/L) in 4/26 patients in the PE+ group. The combination of a normal Vd/Vt and D-dimer concentration was 100% sensitive (95% CI = 88-100%) in excluding PE. Falsepositive testing (either test positive) occurred in 49/14 subjects (specificity 65%, 95% CI = 52-73%). The age-adjusted alveolar-arterial O2 gradient was 33 5 38 torr in the PE+ group vs 13 2 37 torr in the PEgroup (p = 0.1 1). Conclusions: In ambulatory patients, the finding of Vd/Vt ~0 . 2 and D-dimers c0.5 pg/L lowers the probability of acute PE.

Objective-To offer clear guidance on the anaesthetic management of Colles' fractures in the accident and emergency (A&E) department in the light of the conflict between existing reports and current trends, and to address the issue of alkalinisation of haematoma blocks. Methods-This was a two centre, prospective, randomised clinical trial with consecutive recruitment ofadult patients with Colles' fractures requiring manipulation to receive either Bier's block or haematoma block. There was subsequent blinded randomisation to alkalinised or non-alkalinised haematoma block. Results-72 patients were recruited into the Bier's block group, and 70 into the haematoma block group. Bier's block was less painfil to give than the haematoma block (median pain score 2.8 v 5.3; P << 0.001), and fracture manipulation was also less painfiu in the Bier's block group (median pain score 1.5 v 3.0; P < 0.01). There was no significant difference in overall A&E transit time between the two groups. There was better initial radiological outcome in terms of dorsal angulation in the Bier's block group (-3.60 v 2.10; P = 0.003). More remanipulations were required in the haematoma block group (17/70 v 4172; P = 0.003). There was a trend towards decreased pain on administration of the alkalinised haematoma block when compared with non-alkalinised haematoma block, but this did not reach significance. There was no difference in pain score on fracture manipulation. There were no complications in either group. Conclusions-Bier's block is superior to haematoma block in terms of efficacy, radiological result, and remanipulation rate; transit times are equal, both procedures are practical in the A&E environment, and there were no complications. Bier's block is the anaesthetic management of choice for Colles' fractures requiring manipulation within the A&E department. (Accid Emerg Med 1997;14:352-356) Keywords: Colles' fracture; Bier's block; haematoma block; alkalinisation Colles' fractures are manipulated using a variety of anaesthetic techniques within the accident and emergency (A&E) department. A survey of the larger A&E departments in 19941 showed that haematoma block had increased dramatically in popularity over the preceding five years, largely at the expense of the general anaesthetic, accounting for 33% of all reductions; a further 33% were performed under Bier's block, a proportion which had remained unchanged over the preceding five years.2 This move away from the use of a general anaesthetic may have been driven by the cost and resource implications of not having to admit patients and prepare them for a formal theatre procedure.It is less clear why the haematoma block, rather than Bier's block, has filled the space left by the general anaesthetic when one reviews the available reports. Case3 retrospectively compared haematoma block, Bier's block, and general anaesthetic in 136 patients and found that there was no difference in the remanipulation rates between the three methods of anaesthesia. No other outcome measures were mea...

Objective-To assess the ability of nurse practitioners in accident and emergency (A&E) to interpret distal limb radiographs, by comparison with senior house officers. Design-Nurse practitioners and senior house officers in 13 A&E departments or minor injury units were shown 20 radiographs of distal limbs, with brief history and examination findings, and asked to record their interpretation. Outcome measure-A total score for each subject was calculated by comparing answers against agreed correct responses.

SUMMARYUse of nurse practitioners in major accident and emergency (A&E) departments is rapidly increasing: currently they are used in 30% of such departments and this is expected to rise to 63% by the end of 1995.Most are trained by a formal programme in the employing hospital but 12% claim to have no formal training. The nurse practitioner could prescribe a limited range of drugs in 82% of major departments with 'official' nurse practi-tioners, but radiograph requesting was permitted in only 57% of such departments: of those not able to request radiographs, 95% blamed radiographers for preventing this.

Objective: To define and measure patient reported prehospital delay in presentation to the emergency department with chest pain and identify simple strategies that may reduce this delay. The authors investigated the null hypothesis that the patients choice of service to call for acute medical help has no effect on the timing of thrombolysis. Method: A prospective observational study of prehospital times and events was undertaken on a target population of patients presenting with acute chest pain attributable to an acute coronary syndrome over a three month period. Results: Patients who decided to call the ambulance service were compared with patients who contacted any other service. Most patients who contact non-ambulance services are seen by general practitioners. The prehospital system time for 121 patients who chose to call the ambulance service first was significantly shorter than for 96 patients who chose to call another service (median 57 min v 107 min; p<0.001). Of the 42 patients thrombolysed in the emergency department, those who chose to call the ambulance service had significantly shorter prehospital system times (number 21 v 21; median 44 v 69 min; p<0.001). Overall time from pain onset to initiation of thrombolysis was significantly longer in the group of patients who called a non-ambulance service first (median 130 min v 248 min; p=0.005). Conclusions: Patient with acute ischaemic chest pain who call their general practice instead of the ambulance service are likely to have delayed thrombolysis. This is likely to result in increased mortality. The most beneficial current approach is for general practices to divert all patients with possible ischaemic chest pain onset within 12 hours direct to the ambulance service.