Life expectancy in severe COPD.
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Belgium↗
Biomedical subjects
C B Cooper
Publications and source records attributed to C B Cooper.
Determination of the anaerobic threshold by gas exchange: biochemical considerations, methodology and physiological effects.
This paper explains the physiological and biochemical basis of the anaerobic threshold (AT), achieved during physical exercise. The lactate concentration is approximately the same at rest in relatively fit adults, in normal sedentary subjects in adult patients with heart disease. But during exercise, the increase of lactate is inversely related to the physical fitness of the individual. During incremental work, the lactate concentration increases initially very little until a distinct metabolic rate (VO2 AT) is reached at which lactate starts to increase steeply (anaerobic threshold/AT; VO2 AT). Above the anaerobic threshold, accelerated glycolysis increases muscle lactic acidosis. This acidosis is buffered primarily by bicarbonate. The bicarbonate-derived CO2 causes an increased alveolar CO2 output relative to O2 uptake. Oxygen uptake is increased virtually linearly with work rate in healthy subjects with a slope of approximately 10 ml O2/min/Watt. VCO2 starts to increase more steeply in the mid-work-rate range after an initial linear behavior. This steepening is caused by an increased CO2 production from the HCO3-buffering of lactic acid for the range of work rates above the AT. Below the AT, the slope of increase in VCO2 is 1 or slightly less, averaging 0.95. Above the AT, it is greater than 1. The submaximal exercise protocol for the determination of AT includes a period of 2-3 min of unloaded cycling, a ramp program with x Watt increase/minute and a recovery period of 2 min. X is the rate of work rate increase per min, so that the incremental period of the exercise test lasts 8-10 min, stressing the patient for only a short time. The anaerobic threshold can be determined during the ramp program using the following four parameters: 1) steeper increase of VCO2 as compared to VO2 (V-slope-method); 2) respiratory exchange ratio = 0.95; 3) PETO2 increase; 4) VE/VO2 increase. The V-slope-method can be successfully applied, not only in healthy volunteers, but also in patients suffering from cardiac and/or pulmonary (breathing abnormalities) diseases. The so far published data show that the anaerobic threshold in healthy people and patients is a highly reproducible, accurately measurable, securely achievable parameter for the non-invasive evaluation of the individual cardiopulmonary exercise capacity.
Acid-Base Equilibrium↗
Factors affecting the components of the alveolar CO2 output-O2 uptake relationship during incremental exercise in man.
The VCO2-VO2 (alveolar CO2 output-alveolar O2 uptake) relationship (V-slope) during increasing work rate (ramp) cycle ergometer exercise has two approximately linear components: a lower component slope (S1) with a value of about 0.95 and a steeper, upper component (S2). We examined the effect of muscle glycogen depletion (protocol 1) and the rate of increase in work rate (ramp rate) without muscle glycogen depletion (protocol 2) on S1 and S2. In protocol 1, ten healthy men with a mean age of 31.4 years (S.D. 6.2) were studied on each of 3 days (days 1 and 3 were control days). They performed a ramp exercise test to maximum tolerance and steady-state tests at rest, during unloaded pedalling and at two constant work rates below their anaerobic threshold (AT). To deplete muscle glycogen before the test on day 2, the subjects performed 2 h of very heavy cycle exercise on the preceding day and fasted overnight. S1 was reduced on day 2 (0.79 compared with 0.95, P less than 0.001), as was the VCO2-VO2 slope derived from steady-state measurements (0.81 compared with 0.99, P less than 0.001), but AT and the slope difference (S2 - S1) were unchanged. In protocol 2, seven healthy men with a mean age of 20.6 years (S.D. 2.4) performed ramp tests at three different rates of increasing work rate (15, 30 and 60 W min-1), each ramp rate being performed twice in random sequence. The ramp rate did not affect S1 but S2 was steeper with the faster rates of work rate increase (1.27, 1.43 and 1.63, respectively, P less than 0.01). Our findings support the concept that the lower component of the V-slope plot (below AT) represents muscle substrate respiratory quotient (RQ) while the difference between S1 and S2 reflects 'excess CO2' derived from bicarbonate buffering of lactic acid.
Adolescent↗
Linear discriminant and multiple regression analyses of anticoccidial triazines.
Quantitative structure-activity relationships among some anticoccidial 2-(substituted-phenyl)-1,2,4-triazine-3,5-(2H,4H)-diones were studied by multiple regression analysis (MRA, the Hansch approach) and by linear discriminant analysis (LDA). With MRA the potencies of these compounds are correlated with their reverse-phase HPLC retention times and their 1H NMR chemical shifts at the 6-position. While the coefficients of the variable terms are significant, the moderate R2 (0.56) of the correlating equation suggests that predictions made from this analysis are not likely to be accurate. LDA supports the idea that these descriptors are related to potency, but the discriminant function does not lead to good classification. However, when coupled with a graphic display of the results, LDA gives a more immediate sense of the synthetic direction to take when seeking highly potent analogues. It is apparent that other important but not yet identified factors also play a role in determining the potencies of these compounds.
Chromatography, High Pressure Liquid↗
Risks of consumption of contaminated seafood: the Quincy Bay case study.
A recent EPA-sponsored study of sediment and seafood contamination in Quincy Bay revealed elevated levels of several complex organic pollutants frequently of concern in human health assessments. A seafood consumption risk assessment was conducted using data from samples collected in Quincy Bay in the methodology developed for EPA's Office of Marine and Estuarine Protection for such assessments. Results showed estimated plausible, upperbound excess cancer risks in the 10(-5) to 10(-2) range. These results are comparable to those found in other seafood contamination risk assessments for areas where consumption advisories and fishing restrictions were implemented. Regulatory response included consumption advisories for lobster tomalley (hepatopancreas) and other types of locally caught seafood. Uncertainties inherent in seafood risk assessment in general and for the Quincy Bay case are discussed, along with implications for further action.
Animals↗
An analysis of sequential physiologic changes in hypoxic cor pulmonale during long-term oxygen therapy.
Physiologic changes were studied retrospectively in 37 patients with hypoxic cor pulmonale who died during long-term oxygen therapy (LTOT). The subjects were assessed during periods of clinical stability for each year on LTOT. At the onset of treatment, their mean age (+/- SEM) was 60.0 +/- 1.3 years, and at the time of death, they were aged 65.0 +/- 1.3 years. The median duration of LTOT was five years. For each year leading up to death, mean values of FEV1, PaO2, and PaCO2 were obtained. A rate of decline of FEV1 of 73 +/- 10 ml/yr was observed, and this was accompanied by a decline in PaO2 of 0.47 +/- 0.01 kPa/yr. Patients died with a mean FEV1 of 0.55 +/- 0.04 L and a PaO2 of 5.1 +/- 0.2 kPa. A small rise in PaCO2 occurred, on average 0.25 +/- 0.09 kPa/yr, throughout the study, but accelerating in many cases during the three years before death. Hypoxic cor pulmonale appears to be associated with a rapid deterioration in airway function, a steady decline in PaO2, and a slow rise in PaCO2 during the years leading up to death. These physiologic changes measured in a stable clinical state while breathing air appear to occur in spite of LTOT. The LTOT may merely prevent death from episodes of severe hypoxemia while the pathophysiologic changes in the lung progress. Hence the benefit to be expected from LTOT is only temporary. Generally, those patients with lower levels of FEV1 will obtain diminishing clinical benefit, inversely related to the severity of airflow obstruction at the time of commencement of LTOT.
Aged↗
Acute effects of external negative pressure ventilation in chronic obstructive pulmonary disease compared with normal subjects.
This study compares the acute physiological effects of external negative pressure ventilation (ENPV) in normal subjects and patients with chronic obstructive pulmonary disease (COPD). The equipment consisted of an airtight jacket (Pneumosuit) and vacuum pump. Minute ventilation (Ve) was recorded using a light-emitting turbine transducer. Oxygen uptake (VO2) and carbon dioxide output (VCO2) were calculated every 30 s. Measurements were made at rest and during ENPV with pressures of -20 cmH2O and -40 cmH2O. The ventilator rate was fixed at 16.min-1. In 10 normal subjects, Ve increased from 8.6 to 22.9 l.min-1 (p less than 0.01) accompanied by an increase in VCO2 from 0.25 to 0.39 l.min-1 (p less than 0.01). In 10 normocapnic COPD patients (arterial carbon dioxide tension (PaCO2) less than 6.0 kPa) Ve increased from 11.5 to 17.1 l.min-1 (p less than 0.01) whilst in 10 hypercapnic patients (PaCO2 greater than 6.0 kPa) Ve increased from 9.7 to 12.4 l.min-1 (p less than 0.01). A change in VCO2 was not detected in the COPD patients, and VO2 did not change in any group. Arterial blood samples were obtained in eight hypercapnic patients. Baseline mean physiological deadspace ventilation (VD) was calculated to be 4.9 l.min-1 (56% of Ve) whilst Ve was 8.8 l.min-1 in this subgroup. During ENPV, arterial oxygen tension (PaO2) increased from 6.8 to 8.2 kPa (p less than 0.01) whilst PaCO2 decreased from 6.8 to 5.8 kPa (p less than 0.01) suggesting that despite the large physiological deadspace, a significant increase in alveolar ventilation had occurred. In advanced COPD, thoracic compliance falls and limits the ventilatory response to ENPV.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Evaluation of a turbine flow meter (Ventilometer Mark 2) in the measurement of ventilation.
We have evaluated a turbine flow meter (Ventilometer Mark 2, PK Morgan, Kent, UK) at low flow rates and levels of ventilation which are likely to be encountered during exercise in patients with chronic respiratory disease. Pulsatile flows were generated from a volume-cycled mechanical ventilator, the flow wave-form was modified by damping to simulate a human breathing pattern. Comparative measurements of ventilation were made whilst varying tidal volume (VT) from 0.22 to 1.131 and respiratory rate (fR) from 10 to 35 min-1. At lower levels of ventilation the instrument tended to underread especially with increasing fR. The calibration factor must be adjusted to match the level of ventilation if the measurement errors are to be within 5%.
Calibration↗
Response to oral theophylline in severe chronic obstructive airways disease.
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Humans↗
Pleural effusions and pancreatico-pleural fistulae associated with asymptomatic pancreatic disease.
Four patients are described in whom recurrent large pleural effusions developed secondary to asymptomatic pancreatic disease. The diagnosis was made by measuring the amylase content of the pleural fluid. Endoscopic retrograde cholangiopancreatography (ERCP) and computed tomography (CT) were useful in demonstrating pancreatico-pleural fistulae. Two patients underwent laparotomy and distal pancreatectomy. One recovered spontaneously after ERCP appeared to relieve an obstruction of the pancreatic duct and the other recovered after a period of parenteral nutrition. We suggest that pleural fluid amylase content should be measured in any case of exudative pleural effusion of unknown aetiology.
Adult↗
Evaluation of five systems to determine technician staffing in a unit dose cart-filling area.
The development and evaluation of predictive systems to determine staffing needs in a centralized unit dose cart-filling area were studied. Data concerning actual cart-filling time and the hospital's daily census, by total beds and by bed type, were collected over 55 days. Four predictive systems were then developed, as follows: simple average, range average, simple regression, and multiple regression. In addition to these mathematical systems, a pharmacist "best-guess" system was devised, whereby the pharmacist directing the cart-filling area estimated the staffing needs on a daily basis during the trial period. The five systems were then used to predict cart-filling time daily over 14 days. During this time, the actual filling time was recorded and compared with the times predicted by the five systems. The differences among the actual or predicted mean cart-filling times for the five systems were not significant. The pharmacist best-guess system was on average the most accurate in detecting different staffing needs; the advantage of this system is that the pharmacist can evaluate differences in work habits among the scheduled technicians, which the mathematical models would be unable to do. The simple average system correlated well with changes in filling time and most precisely predicted variability in census. Although none of the systems was superior in all respects, a combination of the pharmacist best-guess and simple-average systems appeared to be the best method for predicting daily technician staffing needs in the central cart-filling area.
Data Collection↗
Twelve year clinical study of patients with hypoxic cor pulmonale given long term domiciliary oxygen therapy.
Patients presenting with chronic obstructive airways disease and hypoxic cor pulmonale were assessed during a period of clinical stability. Seventy two patients (53 male) with a mean age of 60 years were selected for long term oxygen therapy. Mean FEV1 was 0.78 l and forced vital capacity 1.9 l. The mean arterial oxygen tension (PaO2) was 6.1 kPa (46 mm Hg) and the mean arterial carbon dioxide tension (PCO2) 6.9 kPa (52 mm Hg). All patients had a PaO2 of less than 8.0 kPa (60 mm Hg) and 57 patients had a PCO2 of more than 6.0 kPa (45 mm Hg). Pulmonary haemodynamics were measured in 45 patients yielding the following mean values: pulmonary artery pressure 28.3 mm Hg; cardiac output 5.9 l min-1; total pulmonary vascular resistance 59.2 kPa l-1 S. Oxygen delivery systems, including 23 oxygen concentrators, were installed in the patients' homes. Flow rates were adjusted to raise PaO2 to more than 8.0 kPa (60 mm Hg) for at least 15 hours each day and close supervision was maintained. Overall five year survival was 62%, which is better than previously reported for this type of patient; but the 10 year survival was only 26% owing to an observed acceleration in death rate at about this time. Progressive disturbances of the pulmonary circulation were arrested. Mortality was associated with the severity of airflow obstruction, reflecting a continuing pathological process affecting the airways.
Aged↗
Salmonella typhimurium and rupture of the thoracic aorta.
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Aged↗
Implementing a stand-alone packaged pharmacy computer system in a 580-bed hospital.
The problems experienced by a hospital pharmacy department in implementing a stand-alone packaged computer system are discussed, and recommendations for avoiding and managing these problems are presented. In 1984, a stand-alone packaged computer system was implemented in a 580-bed, tertiary-care institution that provides services from a central pharmacy and five satellite pharmacies. The department developed a request for proposal and contracted with a vender for a system that would support unit dose drug distribution and i.v. admixture services. During the implementation process, the following problems were experienced: The hardware was insufficient for the department's workload, the software design was limited, and personnel were frustrated with learning to use the system. These problems were intensified by the heavy workload and the large number of users. In the 18 months since implementation, the department has purchased more hardware, improved the software applications, and resolved many of the problems associated with employee frustration. Pharmacy departments at other large institutions might avoid some of these problems by training personnel adequately before implementation and by researching and estimating hardware and software needs in advance. In this large hospital, the efficiency of a stand-alone packaged pharmacy computer system has improved 18 months after implementation.
Computers↗
Severe diaphragm weakness in multiple sclerosis.
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Adult↗
Cellulose granuloma in the lungs of a cocaine sniffer.
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Adult↗
Syndrome resembling graft-versus-host disease in a patient with disseminated carcinoma.
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Aged↗
A case of Lassa fever: experience at St Thomas's Hospital.
An 18-year-old Nigerian girl, normally resident in Jos, was admitted to hospital for five days before she was diagnosed as having Lassa fever. There were several atypical features in the early stages of here illness, notably the absence of prostration, pharyngitis, or bradycardia and the development of appreciable leucocytosis. Consequent control and surveillance measures required checks for 21 days on 173 people who had had contact with as first line if they had handled her or specimens without taking precautions to avoid direct skin contact with her excretions, secretions, and blood; other contacts were categorised as second line. During her time in hospital she was managed in a single room on a general ward. She visited a number of investigative departments within the hospital, and her specimens were examined in five clinical laboratories. Despite this no secondary cases occurred among either first- or second-line contacts, and there was no serological evidence of subclinical infection among any of the contacts tested (159 people).
Adolescent↗