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Biomedical subjects

N M Wilson

Publications and source records attributed to N M Wilson.

At least 19 recordsLinked to original sources
PubMed1997

Factors relating to the severity of symptoms at 5 yrs in children with severe wheeze in the first 2 yrs of life.

Wheezing in early childhood covers a wide spectrum of morbidity. Since little is known about the factors determining either the pattern or the severity of this range of symptoms, 51 children, admitted to hospital with acute wheeze in the first 2 yrs of life, were monitored prospectively between the ages of 4.5-5.5 yrs. Our hypothesis was that the predictors of severe episodes and of interval symptoms in 5 year olds would differ. Symptom diaries were kept, from which the symptom pattern and severity was assessed. The frequency and severity of acute episodes were analysed separately from day-to-day (interval) symptoms. A physiological assessment was made at 5 yrs. During the 12 month study period, 11 children were symptom-free, 15 were reported to wheeze only in response to viral infections, and 25 wheezed from multiple triggers. Bronchial responsiveness was significantly increased in those with a family history of asthma but was unrelated to any index of atopy. In a multiple logistic regression analysis, a family history of asthma and a personal history of allergy (but not results of skin-prick testing or serum immunoglobulin E (IgE) significantly predicted both attack severity and interval symptoms. An additive effect of two factors (atopy plus a family history of asthma or bronchial responsiveness) on symptom severity was suggested, without any evidence of an interaction. It is concluded that in this population of 5 year olds, with an early history of severe wheezing, familial bronchial responsiveness and atopy of operated independently to determine both interval symptoms and attack severity.

Acute Disease↗
PubMed1997

Management of chylothorax.

BACKGROUND: Chylothorax is a rare primary or secondary condition the optimum management of which remains uncertain. METHODS: Twenty cases of chylothorax, including ten of primary chylothorax and ten secondary to either malignancy, subclavian vein thrombosis or lymphangioma treated between 1956 and 1986 have been reviewed. RESULTS: Open pleurectomy was the most successful treatment in preventing reaccumulation of the effusion. Three patients had thoracic duct-azygous vein anastomoses, but all anastomoses were probably occluded within a year of surgery. Three patients have been lost to follow-up and five died within 2 years of their treatment, but 12 patients were alive and free from an effusion 3-22 years after treatment. CONCLUSION: Patients with chylothorax should undergo lymphangiography to identify the cause and site of the lymphatic abnormality. Conservative treatment is successful in some patients but should be abandoned if the fluid loss exceeds 1.5 l/day for more than 5-7 days in an adult or more than 100 ml/day in a child. Parietal pleurectomy is the most successful treatment when no distinct chylous leak can be identified. Less commonly, an isolated chylous leak either in the chest or in the abdomen may be identified and this should be treated by direct ligation.

Adult↗
PubMed1996

Evaluation of a new interrupter device for measuring bronchial responsiveness and the response to bronchodilator in 3 year old children.

The interrupter technique for measuring airway resistance is non-invasive and convenient, and therefore ideally suited for the assessment of induced changes in airway calibre in preschool children. The aim of this study was to evaluate a commercially available interrupter device (based on Microlab 4000), which calculates the interrupter resistance (Rint) from pressure and flow following a brief interruption of expiration during quiet breathing. The repeatability of Rint was assessed, and its response to methacholine challenge and the bronchodilator salbutamol were compared with an indirect technique, the fall in transcutaneous oxygen tension (Ptc,O2), using the sensitivity index (SI, i.e. the change after challenge expressed in multiples of the baseline standard deviation) in 12 wheezy children (aged 3 yrs +/- 2 months). The mean (SD) baseline value of Rint was 0.91 (0.20) kPa.L-1.s. Short-term repeatability and baseline variability were satisfactory for Rint (intraclass correlation coefficient = 0.6; mean intrasubject coefficient of variation = 13%). Although 10 of the 12 subjects obtained a significant response using Rint at maximal bronchoconstriction (i.e. SI > 2), overall, Rint was five times less sensitive than Ptc,O2 (geometric mean SI: Rint 3 vs Ptc,O2 16; p < 0.0001). Reversal of obstruction with administration of a bronchodilator was clearly demonstrated in almost all subjects: Rint after challenge (mean +/- SD) 1.25 (0.22) kPa.L-1.s; after salbutamol 0.78 (0.19) kPa.L-1.s; p < 0.001. In conclusion, the convenient interrupter resistance method appears more promising for detecting bronchodilator responses than induced bronchoconstriction in wheezy preschool children; however, measurement of transcutaneous oxygen tension provides a reliable indirect means of detecting induced airway obstruction in this age-group.

Airway Resistance↗
PubMed1995

Influence of screening on the incidence of ruptured abdominal aortic aneurysm: 5-year results of a randomized controlled study.

From family medical practices 15775 men and women aged 65-80 years were identified and randomized into two groups: one group was invited for ultrasonographic screening for abdominal aortic aneurysm (AAA), and the other acted as age- and sex-matched controls. Of the 7887 invited for screening 5394 (68.4 per cent) accepted. AAA was detected in 218 (4.0 per cent overall and 7.6 per cent of men). Aortic surgery was offered to the screened group if certain criteria were met and no patient died from rupture who was fit for operation and accepted elective treatment. The incidence of rupture was reduced by 55 per cent in men in the group invited for screening, compared with controls. The incidence of rupture in women was low in both groups.

Age Factors↗
PubMed1995

Evaluation of the interrupter technique for measuring change in airway resistance in 5-year-old asthmatic children.

The interrupter technique is a noninvasive method for measuring airway resistance during quiet breathing which requires minimal subject cooperation. It, therefore, has enormous potential for use in young children unable to cooperate with conventional lung function tests. We evaluated the interrupter technique during bronchial challenge with methacholine administered by the tidal breathing method in 10 5-year-old asthmatic children. The mouth pressure/time [P mo(t)] curve obtained following brief airflow interruption during the expiratory phase of quiet breathing was analyzed to determine the interrupter resistance (Rint) using four different methods: RintC, a smooth curve fit with back-extrapolation; RintEO, calculated from the pressure change after the postinterruption oscillations had decayed (end-oscillation); RintL, two-point linear fit with back-extrapolation; and RintEI, calculated from the pressure change at the end of the period of interruption. The four Rint methods were compared for repeatability and sensitivity with the direct measurement of resistance by the forced oscillation technique (Rrs), and with an independent method of measuring the response to challenge, utilizing the change in transcutaneous oxygen tension (PtcO2). The sensitivity of the methods was defined by a sensitivity index (SI), the change after challenge expressed in multiples of the baseline standard deviation. The PtcO2 method had the lowest variability and was by far the most sensitive method (geometric mean SI 18.9), at least 1 doubling concentration more sensitive than the other techniques in every subject (P < 0.05). RintL was more sensitive than the other interrupter methods (geometric mean SI: RintL 4.2; RintC 1.0; RintEO 2.7; RintEI 3.1; P < 0.05) and similar in sensitivity to Rrs (geometric mean SI 4.6) in 7 out of 10 children in which this could be measured. We conclude that the interrupter method provides a simpler method than the oscillation technique for assessing airway obstruction in this age group.

Airway Resistance↗
PubMed1995

Bronchial responsiveness and symptoms in 5-6 year old children: a comparison of a direct and indirect challenge.

BACKGROUND: The level of bronchial responsiveness in those with definite asthma correlates with disease severity and markers of airway inflammation. However, in population studies no clear distinction between normal and abnormal is found. Since the outcome of wheeze in early childhood is very variable, a marker of underlying airway inflammation would be of practical value. A stimulus acting indirectly may be more appropriate than one acting directly on smooth muscle. In this study the airway response to a direct (methacholine) and indirect (hypertonic saline) challenge have been compared in 5-6 year old children with past or present wheeze to see if symptom patterns or severity could be distinguished by either test. METHODS: Forty children with a wide spectrum of wheeze were monitored for a six month period after which their pattern and severity of symptoms were graded. Hypertonic saline and methacholine challenges were then performed on separate days. The response was assessed by both respiratory resistance (Rrs6) and transcutaneous oxygen (PTCO2). Atopic status was determined by IgE and skin prick tests. RESULTS: The results of both challenges were similar whether assessed by Rrs6 or PTCO2. There was no difference in the response to either methacholine or saline between different symptom patterns or severity grades, nor was there any correlation with either test to atopic status. CONCLUSIONS: Neither an indirect nor a direct challenge distinguished between past or present wheeze or degree of clinical severity in this group of children. Either wheezy children of this age do not have airway inflammation or bronchial responsiveness is not a marker for it.

Asthma↗
PubMed1995

The measurement of methacholine responsiveness in 5 year old children: three methods compared.

The aim of this study was to compare the feasibility of three techniques for measuring the response to bronchial challenge in young children: a direct airway measurement, the forced oscillation technique (FOT) for determining respiratory system resistance at 6 and 8 Hz (Rrs6 and Rrs8), and two indirect methods, the change in transcutaneous oxygen tension (PtcO2) and the detection of wheeze on auscultation of the chest. Thirty children aged 5 yrs, with a history of wheeze, and six asymptomatic controls, took part in a bronchial challenge test using methacholine administered by Wright nebulizer by the tidal-breathing method. The provocative concentration which produced a 35% increase in Rrs6 (PC35Rrs6) and a 15% decreases in PtcO2 (PC15PtcO2) were determined by interpolation, and the chest was ausculated after each dose of methacholine. The FOT was found to be unreliable in this age group: in seven children, the data were technically unsatisfactory in the presence of induced bronchoconstriction, whilst in three children, changes in Rrs were inconsistent after challenge. The use of Rrs8 did not improve the detection of positive responses. PC15PtcO2 was measurable in 29 of 30 children, and in 18 of these PC35Rrs6 was also measurable. In no subject did a significant, sustained increase in Rrs occur during challenge in the absence of a significant change in PtcO2. Wheeze was audible in only 4 of 25 (16%) of the positive and in no negative challenges. With this protocol, we found the FOT to be unreliable and the auscultation method valueless and potentially dangerous, since marked falls in PtcO2 of up to 33% sometimes occurred in the absence of wheeze.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1994

Surgical workload as a consequence of screening for abdominal aortic aneurysm.

A study was performed to evaluate the surgical workload that has resulted from screening an at-risk population for abdominal aortic aneurysm (AAA) and to forecast the likely workload from an established screening programme. Over an 8-year period 8944 people aged 65-80 years were screened; 356 were found to have an AAA of 3 cm or greater in diameter. There were 288 outpatient consultations involving 171 patients, and 43 patients (4.8 per 1000 screened) had surgery during the study period. A fully operational screening programme for a population of 250,000, screening men and women at a rate of 2000 per year, would be expected to produce a surgical workload of nine or ten operations for AAA per year. Screening men only would increase this to 34 annually.

Aged↗
PubMed1994

Daytime sleepiness in insomnia: behavioral, biological and subjective indices.

We compared three measures of daytime sleepiness, sleep behavior (as measured by the multiple sleep latency test), a biological index of sleepiness (pupillometry) and subjective sleepiness (as measured by the Stanford Sleepiness Scale), in evaluating middle-aged individuals with psychophysiological insomnia (n = 20) or no sleep problem (n = 20). Subjects underwent polysomnography (PSG) and four multiple sleep latency test/pupillometry trials the following day. The results determined that neither behavioral, biological nor subjective indices distinguished these two groups. Differentiating the insomniacs into true insomniac (n = 14) and normal sleeping insomniac (insomniacs with sleep efficiency greater than 90%, n = 6) subgroups based upon PSG did not improve daytime discriminations. Furthermore, nighttime sleep experience, measured by either PSG or self-report, was not a strong predictor of these daytime indices among either insomniacs or noninsomniacs. The results of this study support the conclusions that insomniacs do not exhibit heightened levels of daytime sleepiness and that routine fluctuations in sleep exert minimal influence on daytime sleepiness among insomniacs and noninsomniacs. The former finding is likely due either to insomniacs satisfying their biological sleep need despite poor sleep or chronic physiological hyperarousal preventing both sleep and sleepiness.

Adult↗
PubMed1993

Is surgery necessary for abdominal aortic aneurysm less than 6 cm in diameter?

During 8 years of an ultrasound screening programme for abdominal aortic aneurysm (AAA), 8944 people aged 65-80 years were scanned. 356 (4%) had AAA of diameter 3 cm or greater. Under our criteria repair was indicated if the aortic diameter reached 6 cm, if expansion reached 1 cm per year, or if the AAA caused symptoms; 124 patients met these criteria. Among the 8820 screened patients who did not meet the criteria, 1 death (0.4%) was attributed to ruptured aneurysm, although the retroperitoneal haematoma had developed within 5 days of surgery for a colon tumour. The risk of aortic rupture in patients with AAA less than 6 cm diameter with these criteria (0.4%) is lower than that for elective surgery (1-8%). Surgical repair is unnecessary and possibly detrimental in such patients, provided that ultrasound surveillance is undertaken.

Aged↗
PubMed1993

Comparison of venous reflux assessed by duplex scanning and descending phlebography in chronic venous disease.

Venous reflux was assessed by duplex scanning and descending phlebography in 98 limbs of 52 patients. There was moderately good agreement for deep vein reflux elicited by a standardised Valsalva manoeuvre, classified by a modified Kistner grading (0 to IV). The same grade was found in 58 limbs, with a difference of one grade in 27 limbs, and more than one grade in 13. Descending phlebography underestimated reflux in the lower leg compared with duplex scanning. The presence of reflux found on duplex scan correlated with the half-volume refilling time on a foot-volume plethysmogram with a below-knee tourniquet. There was no correlation between descending phlebography and the half-refilling time. Ascending phlebography showed post-thrombotic changes in 23 limbs. The duplex scan confirmed severe reflux (grades III and IV) in 14 of these 23 limbs, and demonstrated isolated reflux below normal valves in 4 other limbs. Severe reflux was seen on the descending phlebogram in only 10 of the 23 limbs with post-thrombotic changes. Duplex scanning may be a better method for detecting reflux than descending phlebography and is more acceptable to the patient. Ascending phlebography remains essential to display anatomical abnormalities found in some postthrombotic limbs that are not associated with reflux.

Adult↗
PubMed1992

Aetiology and treatment of chylous ascites.

A series of 45 patients with chylous ascites has been reviewed. The age at presentation ranged from 1 to 80 (median 12) years; 23 patients were aged < or = 15 years. Thirty-five patients had an abnormality of the lymphatics (primary chylous ascites); in the remaining ten, the ascites was secondary to other conditions, principally non-Hodgkin's lymphoma (six patients). Two principal mechanisms of ascites formation were identified using lymphangiography and inspection at laparotomy: leakage from retroperitoneal megalymphatics, usually through a visible lymphoperitoneal fistula (14 patients); and leakage from dilated subserosal lymphatics of the small intestine, invariably associated with leaking lacteals causing protein-losing enteropathy (24 patients). Both sites of leakage were present in a further five patients. In the remaining two patients, chyle was leaking from normal mesenteric lymphatics, in one via a ruptured mesenteric lymph cyst and in the other from the site of a previous lymph node biopsy. Other associated lymphatic abnormalities were present in 36 patients, lymphoedema of the leg being the commonest (26 patients). All patients were initially treated conservatively with dietary manipulation; this was the most satisfactory treatment for those with leaking small bowel lymphatics. Surgery (fistula closure, bowel resection or insertion of a peritoneovenous shunt) was performed in 30 patients. Closure of a retroperitoneal fistula, when present, was the most successful operation, curing seven of the 12 patients so treated.

Adolescent↗
PubMed1992

Atopy, bronchial responsiveness, and symptoms in wheezy 3 year olds.

Fifty children with at least one hospital admission for acute lower airway obstruction in the first 2.5 years of life were assessed at 3 years of age to determine the relationship between atopy, bronchial responsiveness, and the pattern of their symptoms. Bronchial responsiveness was measured by assessing the effect of inhaled metacholine, using the change in transcutaneous oxygen tension (PtCO2) as an indirect measure of response. Symptom patterns were defined by the number of wheezing episodes associated with colds and the presence or absence of cough or wheeze unrelated to viral infections. Forty per cent of the children were found to be atopic by skin prick test or history. In contrast to the situation found in older children and adults, the non-atopic children had significantly greater bronchial responsiveness (lower mean concentration of methacholine causing a 20% fall in PtCO2, the PC20) than the atopic children and significantly more of them had an onset of respiratory symptoms in the first year of life. Cough and wheeze in the absence of colds was more frequently found in the atopic children as was the use of continuous medication. However, the number of reported acute episodes of wheeze associated with colds was the same in the two groups. The findings of the study suggest that in this hospital based group of children, acute wheeze associated with colds in the first three years of life is independent of the finding of atopy and that bronchial responsiveness in this age group may have a different pathogenesis from that in older subjects.

Blood Gas Monitoring, Transcutaneous↗
PubMed1992

Repeatability of methacholine challenge in asthmatic children measured by change in transcutaneous oxygen tension.

BACKGROUND: The airway response to bronchial provocation may be evaluated by monitoring the fall in transcutaneous oxygen tension (PtcO2) but the repeatability of this method has not been rigorously assessed. METHODS: To determine the repeatability of this indirect method of assessment, bronchial challenge was performed with methacholine in nine children with stable asthma (age range 6-12 years) and was repeated 24 hours later. The response was determined by the fall both in forced expiratory volume in one second (FEV1) and in PtcO2. A modified tidal inhalation protocol was used in which quadrupling concentrations of methacholine were given, thereby reducing the time taken for the full challenge by almost half. The concentrations of methacholine that provoked a 20% decrease in FEV1 (PC20FEV1) and 15% and 10% falls in PtcO2 (PC15PtcO2, PC10PtcO2) were calculated. RESULTS: Repeatability measures, assessed as the 95% range for a single determination, were +/- 0.96 and +/- 1.12 doubling concentration differences respectively for PC15PtcO2 and PC10PtcO2 and +/- 0.80 for PC20FEV1. CONCLUSION: This challenge method using quadrupling concentrations and an indirect assessment of the response by PtcO2 was sufficiently repeatable for clinical use and compared favourably with repeated challenge assessed by FEV1. The PtcO2 method is simple and effort independent, and should prove particularly useful for measuring bronchial reactivity in young children.

Asthma↗