No abstract

(7Accid Emerg Med 1996;13:406-408)

485and carboxyhaemoglobin wras 0 98 (n 182) for the normal smokers (standard error of estimate of carboxyhaemoglobin from a given EGO was 0 76 ,) and 0-92 (n 35) for the patients with emphysema (figure). The slopes of the twso regression lincs were significantly different (F 5-8; df 33, 180; p<0001). A stepwise multiple rcgression analysis of the data from the normal smokers showed, in addition to the linear ECO component, a significant quadratic ECO component and a significant age componcnt. CommentThe difference between the slopes of the linear regressions of the normal smokers and the patients with emphysema shows that impaired lung function affects the relationship between expired air carbon monoxide and carboxyhaemoglobin. In emphysema a given concentration of expired air carbon monoxide is associated with a higher carboxyhaemoglobin, reflecting impaired diffusion of carbon monoxide from blood into the alveoli. The small age effect found in the multiple regression should also be interpreted in this way. Nevertheless, imoairbd lung function cannot be an important factor in normal smokers, since only 3",, of the variation in carboxyhaemoglobin remained unaccounted for after allowing for linear and quadratic ECO components and age. The closeness of the relationship between carboxyhaemoglobin and expired air carbon monoxide suggests that there is little to be gained from analysing a sample of blood rather than expired air. Indeed, there is likely to be as much variation between different blood measures for carboxyhaemoglobin as was found for the two measures in the present study.The expired air method has numerous advantages. It is non-invasive, portable, cheap, quick, and requires no specialist technical back-up. Because it is quick the results can immediately be fed back and explained to the smoker, which may well have an appreciable motivating effect. Smokers' claims to have stopped smoking can be instantly checked. It also has potential as a measure of smoke intake in epidemiological studies.

Objective: To evaluate the effectiveness of injury prevention training. Design: Cluster randomised controlled trial. Setting: Primary care facilities in the East Midlands area of the United Kingdom. Subjects: Midwives and health visitors. Intervention: Evidence based training session on the risks associated with baby walkers. Main outcome measures: The primary outcome measures were knowledge of baby walker use and walker related injury, attitudes towards walkers and towards walker education, and practices relating to walker health education. Results: Trained midwives and health visitors had greater knowledge of the risks associated with baby walkers than untrained midwives and health visitors (difference between the means 0.22; 95% confidence interval (CI) 0.12 to 0.33). Trained health visitors had more negative attitudes to baby walkers (difference between the means 0.35; 95% CI 0.10 to 0.59) and more positive attitudes towards baby walker health education (difference between the means 0.31; 95% CI 0.00 to 0.62) than untrained health visitors. Midwives who had been trained were more likely to discuss baby walkers in the antenatal period than those who were not trained (odds ratio 9.92; 95% CI 2.02 to 48.83). Conclusions: Injury prevention training was associated with increased knowledge, more negative attitudes towards walkers, and more positive attitudes towards walker education. Trained midwives were more likely to give advice antenatally. Training did not impact on other practices. Larger trials are required to assess the impact of training on parental safety behaviours, the adoption of safety practices, and injury reduction.

SHORT REPORTSOphthalmoplegia, amblyopia, and diffuse encephalomyelitis associated with pelvic abscess Duke-Elder' included focal sepsis as a cause of optic neuritis, though he thought the association was uncommon. We describe here a patient who presented with optic neuritis with no apparent cause but whose neuro-ophthalmological symptoms disappeared after removal of a pelvic abscess. Case reportAn 18-year-old girl was admitted with a two-week history of headaches, backache, neck stiffness, and hyperacusis. One week before admission she developed intermittent diplopia, failing vision, and ataxia. Her last period had occurred three and a half months earlier. There was no history of drug abuse.On examination she was feverish, drowsy, slow, and inconsistent in her replies. She had mild neck stiffness and a positive Kernig's sign. There were no marks of injection, bruises, abrasions, rash, or lymphadenopathy. There was a retrouterine mass, the size of a four-month pregnancy, which was fixed, non-tender, and firm.Neurologically the eyes were immobile on all forms of testing, and the pupils were slightly divergent, irregular, and dilated and did not react to light. She could just detect hand movements but suffered no localised field loss. Examination of the fundi showed bilateral, sharply defined, whitish exudates over the disc and distension of surrounding vessels. There were no haemorrhages and the peripheral vessels were normal. Apart from mild deafness the remaining cranial nerves were normal but her arms were ataxic and she could not stand. All tendon jerks were reduced and the plantar responses were flexor.

Hypocalcaemia has been reported in the fat embolism syndrome, but it is said to be non-specific.' We describe here a case where a directly measured low ionised calcium (Ca2+) concentration alerted us to the diagnosis of fat embolism. Subsequent measurements of Ca2 + proved to be an accurate index of recurrent embolic episodes. Case reportA 27-year-old man sustained a displaced fracture of the right tibia and fibula after a road-traffic accident. No other significant inijury was sustained.The fracture was manipulated under general anaesthesia and the leg immobilised in full-leg plaster. Two days later the patient complained of sudden retrosternal chest pain radiating to the neck and arms. On examination he had a tachycardia of 120/min with normal blood pressure and respiratory rate of 20/min. An electrocardiogram showed T-wave inversion over the anterolateral leads. The measured Ca2 + was 1 06 mmol/l (4-24 mg/ 100 ml) (Orion SS-20, normal range 1-15-1-30 mmol/l (4-6-5-2 mg/100 ml)) with an arterial pH of Conversion: SI to traditional units-Calcium: 1 mmol/l 4 mg/ 100 ml. total calcium, and calcium corrected for albumin during this period. Control values relate to an age-and sex-matched patient confined to bed with a fractured 12th rib. CommentThe course of the embolism syndrome in this case was uncommon and differed from the usual clinical course of fat embolism. The classic clinical syndrome of respiratory insufficiency, progressive arterial hypoxaemia, disorientation and other cerebral effects, pyrexia, tachycardia, and petechial rash usually begins 12-72 hours after injury. In a recent study2 hypocalcaemia was found in eight out of 100 patients with the clinical syndrome of fat embolism and the authors did not list this as of diagnostic significance. The mechanism of hypocalcaemia is not understood but may result from the binding of Ca2 + to free fatty acids said to be liberated by local lipolysis, possibly in the lungs. Raised serum lipase values have been reported in 40¾) of patients with fractures three to five days after trauma3 but may also be non-specific. Fatty acid binding would affect the total calcium only if the fall in Ca2 + is substantial. Theoretically the Ca2 + as directly measured by the Orion SS-20 should be a much more sensitive index of calcium homoeostasis than the measured total calcium. In this patient the ionised calcium was low before other signs of fat embolism became apparent. Furthermore, the Ca2 + fell with each subsequent deterioration and seemed to correlate well with a recurrent clinical episode. Total calcium values estimated at the same time were within the normal range.There is no single laboratory test which can be used to diagnose fat embolism. Those "simple" tests which are available are time consuming4 and their results often do not correlate with the clinical severity of the syndrome.2 The development of flow through specific ion electrode analysers such as the Orion SS-20 now allows accurate estimations of Ca2 +, while being easy to use and within the scope of most labo...

Health visitor advice regarding walkers needs to be given earlier in the postnatal period than is currently common practice, and they need more knowledge about walker use and related injuries. Education about baby walkers needs to be incorporated into undergraduate and in-service education, which may need to include the development of skills in exploring reasons why parents use walkers and in negotiating alternatives to their use. The provision of audio-visual aids for discussing walkers might also be helpful.

SUMMARYThe correct diagnosis was initially suspected in 32 (53%) of 60 patients with ectopic pregnancy who attended an accident and emergency department. Incorrect diagnoses were made because ectopic pregnancy was not considered or because relevant symptoms and signs were missed or misinterpreted. Three patients had been 'sterilized'. Twenty-four patients (40%) had abdominal pain or vaginal bleeding for more than 1 week before attending. Fever and leucocytosis were wrongly attributed to pelvic infection. Pregnancy tests were positive in 56% of the patients tested.