Biomedical subjects
K Prowse
Publications and source records attributed to K Prowse.
Comparative study of automatic blood-gas analysers and their use in analysing arterial and capillary samples.
Three automatic blood-gas analysers were compared for ease of use; calibration; reproducibility and accuracy of results; maintenance; fault-finding; and use of expert technician time. Results obtained from arterial and capillary blood were compared with duplicate values obtained with a semi-automatic analyser controlled and calibrated with tonometered blood. No analyser was fully automatic, and all three needed maintenance by expert technicians. Difficulties were encountered when inexperienced operators used the machines. One automatic blood-gas analyser gave aberrant values for oxygen pressure (PO2) due to electrode dysfunction that was not indicated by the fault-finding system. A second analyser gave significantly lower values for blood pH than the standard machine. A comparison of pH, carbon dioxide pressure (PCO2), and PO2 measured in 40 simultaneous paired samples of arterial and arterialised capillary blood showed no significant difference for pH or PCO2, but the PO2 values were significantly lower in the capillary samples over the range studied. We conclude that all machines perform satisfactorily in terms of blood-gas analysis, but none may be regarded as fully automatic. Some degree of technical supervision is essential, as is proper training for all potential users.
An evaluation of the mini-Wright peak flow meter.
The mini-Wright peak flow meter (MPFM) has been evaluated, and the results obtained from it show a strong positive correlation (r=0.970) with the Wright's peak flow meter (PFM). MPFM measurements, however, were biased to be about 38 1/min higher than PFM measurements (95% confidence limits 31.01/min to 45.01/min). Between instrument variation was found (F--ratio 3.67 with 9 and 81 degrees of freedom: P less than 0.001). In practice this did not appreciably affect individual measurements greatly as 95% confidence limits on any individual measurements were increased from +/-24 1/min to +/-27 1/min. There was no significant day-to-day variability in measurements obtained with individual instruments. The MPFM is a pocket-sized, simple, cheap, and robust instrument for following changes in ventilatory function. In clinical trails and surveys, however, both the bias in favour of the MPFM compared to the PFM and inter-machine variation must be taken into account. As the manufacturers have altered the scale to remove the bias since this study was performed, it will be important to know whether the original or the modified meter is being used in future studies.
Demeclocycline in the treatment of the syndrome of inappropriate secretion of antidiuretic hormone.
Fourteen patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) have been treated with demethylchlortetracycline (demeclocycline) 1200 mg daily. In 12 patients the underlying lesion was malignant. The serum sodium returned to normal (greater than 135 mmol/l) in all patients after a mean of 8.6 days (SD +/- 5.3 days). Blood urea rose significantly from the pretreatment level of 4.2 +/- 2.3 mmol/l to 10.1 +/- 5.1 mmol/l at ten days (P less than 0.001). The average maximum blood urea was 13.4 +/- 6.8 mmol/l. In four patients the urea rose above 20 mmol/l, and in two of these demecyocycline was discontinued because of thie rise. The azotaemia could be attributed to a combination of increased urea producation and a mild specific drug-induced nephrotoxicity. Discontinuation of demeclocycline in six patients led to a fall in serum sodium, in one case precipitously, and return of the urea towards normal levels. Demeclocycline appears therefore to be an effective maintenance treatment of SIADH, and the azotaemia that occurs is reversible and probably dose dependent.
Can aminophylline reduce the need for oral corticosteroids?
Fifteen patients with long-standing chronic obstructive airways disease, who had received oral prednisolone for at least one year with objective and subjective response were included in the study. Attempts to reduce or withdraw steroids had been made unsuccessfully on at least two occasions in all cases. Phyllocontin Continus tablets were given at a dose of 225 mg in the morning and 450 mg at night for a 33-week period. One patient was withdrawn after 8 weeks due to side-effects. Four patients had their oral prednisolone withdrawn entirely and a further seven had a beneficial reduction without adverse effect on FEV1 or VC. The average reduction in daily dosage of steroids was from 10 mg to 4.97 mg (p less than 0.001) with an associated rise in mean FEV1 of 1.69 to 1.92 litres.
Medical chests--asthma, bronchitis and emphysema.
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The respiratory response to inhaled carbon dioxide in man after 3 hours exposure to 3% carbon dioxide.
1. The respiratory response to inhaled 3% and 6% CO2 was measured in 10 normal subjects after a 3 h acclimatization period to 3% CO2 in an environmental chamber. Control studies were carried out after a 3 h period of breathing air in the chamber. 2. At the end of the acclimatization period studies were carried out during 20 min periods breathing 3% CO2, 6% CO2 and air. 3. At 2-min intervals during the studies measurements were made of tidal volume (Vt), breathing frequency (fR), minute ventilation (Ve), viscous pulmonary rate of work (Wp) and total viscous rate of work across the lungs and apparatus (Wt). Blood gas tensions were measured at the end of this period. 4. After acclimatization to 3% CO2 there was a significant shift in the response curves Ve/Pa,CO2 and Wt/Pa,CO2 such that subjects showed higher Pa,CO2 values for given values of Ve or Wt. There was no significant change in the slope of the response curves. 5. No correlation was found between the slope of the response curve after the control period breathing air and the degree of shift of the response curve. 6. There was no difference in respiratory pattern or in pulmonary resistance. 7. Similar results were found in two subjects studied after 24 h acclimatization to 3% CO2 but one subject also showed a significant change in the slope of the Ve/Pa,CO2 curve.
Treatment of pulmonary aspergillosis with di-iodohydroxyquinoline.
Thirteen patients with a clinical diagnosis of pulmonary aspergillosis were treated with the anti-amoebic drug di-iodohydroxyquinoline, 1500-1800 mg/day orally, for 20 days. All were precipitin positive before treatment and all but one became negative after treatment. Sputum became negative in all of the 10 patients in whom it had been positive before treatment. Clinical improvement was marked in four patients, moderate in three, and slight in three, no change occurring in the remaining three. These results suggest that di-iodohydroxyquinoline may be of value in the treatment of pulmonary aspergillosis.
Tuberculosis in the Potteries 1971-74.
Notification rates of all forms of tuberculosis have increased in all age-groups in the Potteries, in a stable population which includes only a small immigrant community. The increase is greatest in both males and females over the age of 65 years and under 15 years. High notification rates have been recorded in workers in the pottery and mining industries and were unrelated to pneumoconiosis. Discrepancies have been found between the numbers of notified cases and the numbers of laboratory isolates of tubercle bacilli, particularly in cases of non-respiratory disease. This indicates that not all proven cases of tuberculosis are notified. The study has revealed serious deficiencies in the contact-tracing procedure in certain areas of the Potteries consequent upon the closure and reorganisation of outlying chest clinics.
Nitrous fume poisoning.
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