Predictors of desaturation during formal hypoxic challenge in adult patients with cystic fibrosis

Assessment of the potential risk of in flight hypoxaemia in patients with cystic fibrosis is often based on a hypoxic challenge where individuals have saturations and/or blood gases taken before and after inspiring 15% normobaric oxygen. The aim of this study was to see if routine clinical measurements could predict the outcome of this test. This was a prospective study comparing the modified 6-min walking test, lung function, body mass index, Northern (N) and Shwachman-Kulczycki (SK) scores with a hypoxic challenge (flight test) in 69 adults attending the Leeds regional CF Unit. Although, there was a significant correlation between post flight test PaO(2) and N score (P=0.003), SK score (P=0.002), FVC % predicted (P=0.01), FEV(1) % predicted (P=0.002), resting saturations (P<0.001), 6 min saturation on walking test (P<0.001) and baseline PaO(2) (P<0.001), no single parameter could accurately predict all patients who desaturated during the flight test. No individual clinical parameter appears to fully predict the need for in flight oxygen but patients most at risk appear to have either a low FEV(1) (<60%), high N score (>13) or low baseline PaO(2) (<10.5 kPa).

Validation of the SF-36 for the assessment of quality of life in adolescents and adults with cystic fibrosis

BACKGROUND

Generic health-related quality of life measures are often applied to disease groups without assessment of their psychometric properties. The current work assesses the properties of the Short Form 36-item (SF-36) questionnaire in a British sample of adolescents and adults with cystic fibrosis (CF).

METHODS

Two hundred and twenty-three adolescents and adults with CF completed the SF-36 with a further 185 approached and not responding by non-completion of the questionnaire. The structure and internal reliability of the instrument was assessed by principal components analysis, Cronbach alpha coefficients and item to domain correlations. Differences between disease severity groups were assessed by analysis of variance.

RESULTS

Factor analysis of the SF-36 scores broadly confirmed domain structures for the SF-36. Cronbach alpha coefficients were high (range 0.82-0.91) and item-to-same domain correlations were stronger than item-to-unrelated domain correlations. Examination of differences between mild, moderate and severe disease states revealed four significant main effects for: physical functioning, role limitation due to physical functioning, general health perceptions and energy and vitality. The analysis also revealed the presence of numerous ceiling effects across domains.

CONCLUSIONS

The domain structure of the SF-36 was demonstrated to be robust. However, the discriminatory ability of the measure was disappointing. The presence of ceiling effects and the low frequency of differences between intermediate disease severity groups indicated that the SF-36 was not discriminatory with respect to mild disease states or progression of illness.

A pilot study of zafirlukast as an anti-inflammatory agent in the treatment of adults with cystic fibrosis

BACKGROUND

Persistent endobronchial inflammation is in part responsible for the attrition of lung function seen in cystic fibrosis. Leukotrienes act as pro-inflammatory mediators. The aim of this study was to assess the efficacy of the leukotriene receptor antagonist zafirlukast as a potential anti-inflammatory agent in the treatment of adult patients with cystic fibrosis.

METHODS

Clinically stable patients were enrolled in the study if they had no history or clinical evidence of asthma, bronchial hyper-reactivity, or aspergillosis. They were randomised to receive zafirlukast 20 mg twice daily with all routine treatment for four months or routine treatment alone in an open cross-over design. Primary endpoints were changes in respiratory function tests and a modified NIH clinical score.

RESULTS

Thirty patients were enrolled and 25 completed. There was a significant improvement in the modified NIH clinical score but no significant increase in respiratory function with zafirlukast.

CONCLUSIONS

Patients receiving a leukotriene receptor antagonist in addition to routine treatments showed significant improvement in a clinical score which is a composite of clinical wellbeing, chest radiograph appearance, and physical examination. Respiratory function showed a non-significant trend towards improvement with treatment. Zafirlukast may benefit patients with CF. An adequately powered study is justified on the basis of these results.

The role of IDA scintigraphy in the follow-up of liver disease in patients with cystic fibrosis

The main aim of this study was to investigate the role of N-(2,4,6 trimethyl-3-bromophenylcarbamoylmethyl) iminodiacetic acid (IDA; Mebrofenin) scintigraphy in follow-up assessments of the biliary system in patients with cystic fibrosis associated liver disease. Fourteen patients from a study published in 1996 were re-examined after a mean interval of 4.7 years from their initial study, in which diisopropylphenyl carboxymethyl iminodiacetic acid (DISIDA) was used. The results of ultrasound, liver function tests and clinical examination were also compared. Twelve of the patients had been treated with ursodeoxycholic acid and taurine in the interim. Five subjects' IDA examinations showed a slight improvement on follow-up, six deteriorated, two were unchanged, whilst one demonstrated a 'mixed picture'. Overall, nine patients deteriorated in one or more of the tests. No patient showed a decline in all four investigations and only two in three. There was poor correlation between the various follow-up examinations, with different patients showing a decline in some tests but not others. This may be due to the mixture of functional and anatomical studies utilized, their differing sensitivies, and the fact that deterioration in one did not necessarily affect another. In conclusion, follow-up of hepatobiliary disease in patients with cystic fibrosis cannot be encompassed by one method alone. If early detection of disease progression would affect management, patients will continue to require a number of investigations rather than a single test.

Once-daily tobramycin in the treatment of adult patients with cystic fibrosis

The aim of this study was to test the equivalence of once- and thrice-daily dosing with tobramycin by comparing efficacy and safety in adult patients with cystic fibrosis. Sixty adult patients with an acute respiratory exacerbation were randomized to receive either 10 mg x kg(-1) tobramycin once-daily or 3.3 mg x kg(-1) tobramycin thrice-daily. Primary efficacy and safety endpoints were defined as changes in respiratory function and changes in renal function and hearing. Both groups showed a significant increase in respiratory function without a clinically significant change in renal function. For changes in forced vital capacity % predicted and serum potassium and magnesium levels, equivalence was demonstrated. For the variables forced expiratory volume in one second and forced mid-expiratory flow % pred and serum creatinine levels, there was insufficient power to demonstrate equivalence. One patient in each group showed bilateral impairment in pure tone audiogram after treatment. This study demonstrated significant clinical improvement with both once- and thrice-daily tobramycin dosing. Equivalence between the two regimens was shown for some, but not all primary endpoints. Once-daily dosing should be used with careful monitoring of safety and efficacy until large multicentre studies confirm these encouraging results.

Cross cultural differences in health related quality of life in adolescents with cystic fibrosis

PURPOSE

Quality of Life (QoL) is an important outcome measure in health care and pharmacological trials. The trend towards multinational clinical trials may be problematic because it is unclear as to whether, or to what extent, QoL-measures are comparable across cultures. This study compared QoL between English and German adolescents with Cystic Fibrosis (CF) and their healthy peers.

METHOD

The study comprised a cross-sectional design. The English subjects formed two groups; 58 adolescents with CF and 49 healthy controls. The German subjects consisted of 26 adolescents with CF and 75 healthy controls. Quality of life was measured using the English and German versions of the SF-36. Demographic (age and gender) and clinical data (FEV1% predicted and BMI) were also recorded.

RESULTS

The English and German CF groups had similar age-adjusted lung function and body mass index. Both the English CF and control groups reported a poorer quality of life than their respective German counterparts across several domains of the SF-36. These were limitations in activities due to physical health problems and emotional difficulties, social functioning, energy and vitality and pain.

CONCLUSIONS

The differences in quality of life between English and German adolescents with CF appear to be either culturally determined or due to idiosyncrasies in the translations of the SF-36. rather than a consequence of their disease or its management.

Perceived body image and eating behavior in young adults with cystic fibrosis and their healthy peers

Treatment aimed at achieving an ideal nutritional status is an integral part of the management of patients with cystic fibrosis (CF). Emphasis is continually placed upon dietary intake and weight. The effects of this on eating behavior and self-perceptions are unclear. This work compared male and female CF adults with a healthy male and female control population with regard to (a) clinical variables, (b) actual, perceived, and desired body shape/body mass index (BMI), and (c) body satisfaction, eating behaviors and attitudes, and self-esteem. Clinical data were recorded for 221 adults with CF and 148 healthy controls. All subjects completed BMI Charts (perception of body weight/BMI), the Eating Attitudes Test, and scales of body satisfaction and self-esteem. CF patients had poorer lung function and nutritional status than controls. Control males accurately perceived their body shape/BMI and were content with it, whereas CF males viewed their BMI as greater than it actually was and desired to be much heavier. Control females viewed their body shape/BMI as less than it actually was and desired to be even slimmer, in comparison with CF females, who perceived their BMI as less than it actually was but were happy with their perceived shape/weight. Control subjects, especially females, dieted to a greater extent and were more preoccupied with food (with binge eating and intended vomiting) than CF patients. Conversely, those with CF reported greater pressure from others to eat than did controls. More problems with food/eating behavior were associated with less body satisfaction and reduced self-esteem. In comparison with a healthy control population, the perceptions and behaviors of CF adults relating to eating, weight, and body image are not abnormal. Indeed, females with CF have fewer problems than their healthy peers.

Safety and tolerability of bolus intravenous colistin in acute respiratory exacerbations in adults with cystic fibrosis

OBJECTIVE

To assess the safety and tolerability of bolus intravenous doses of colistin during acute respiratory exacerbations in adults with cystic fibrosis and chronic Pseudomonas aeruginosa infection.

METHODS

Twelve patients with acute exacerbations of cystic fibrosis were enrolled in a Phase I open-label study. On day 1, patients received three doses of colistin 2 mega-units (160 mg), reconstituted in 50 mL of NaCl 0.9%, by infusion over 30 minutes three times daily. On days 2, 3, and 4, the same dose of colistin was administered by bolus injection three times a day over five minutes after reconstitution in 20, 15, and 10 mL of NaCl 0.9%, respectively. The injection was given by a nurse or physician using a hand-held syringe. If the latter dose was tolerated, it was continued for the remaining eight days of the study. If any dose was not tolerated, treatment reverted to the previously tolerated concentration, which was continued throughout the remainder of the study.

RESULTS

No serious adverse events occurred during the course of the trial. Patients without total indwelling venous access systems experienced mild to moderate injection pain. There were no clinically significant changes in renal function.

CONCLUSIONS

This study indicates that the administration of bolus intravenous colistin as 2 mega-units (160 mg) in 10 mL of NaCl 0.9% three times a day is safe. It is well-tolerated by patients with total indwelling venous access systems.

Development of a disease specific health related quality of life measure for adults and adolescents with cystic fibrosis

BACKGROUND

Health related quality of life (HRQoL) measurement is important in determining the impact of disease on daily functioning and subsequently informing interventions. In cystic fibrosis (CF) generic HRQoL measures have been employed but these may not be sufficiently specific. The aim of the current work was to develop and validate a disease specific HRQoL measure for adults and adolescents with cystic fibrosis.

METHODS

Areas of concern to adults and adolescents with CF were identified by unstructured interviews, self-administered questionnaires, consultation with multidisciplinary specialist staff, a review of the relevant literature, and examination of other HRQoL measures. Items for the questionnaire were generated on the basis of this process. Continued evaluation and development of the Cystic Fibrosis Quality of Life (CFQoL) questionnaire was undertaken by a process of statistical analysis and continued feedback from patients. The full testing and validation of the CFQoL questionnaire took place over four phases: (1) initial item generation and testing of a preliminary questionnaire, (2) testing and validation of the second version of the questionnaire, (3) test-retest reliability of a third and final version of the questionnaire, and (4) sensitivity testing of the final version of the questionnaire.

RESULTS

Nine domains of functioning were identified using principal components analysis with varimax rotation. Internal reliability of the identified domains was demonstrated using Cronbach alpha coefficients (range 0.72-0.92) and item to total domain score correlations. Concurrent validity (range r = 0.64-0.74), discriminatory ability between different levels of disease severity, sensitivity across transient changes in health (effect size range, moderate d = 0.56 to large d = 1.95), and test-retest reliability (r = 0.74-0.96) were also found to be robust.

CONCLUSIONS

The CFQoL questionnaire is a fully validated disease specific measure consisting of 52 items across nine domains of functioning which have been identified by, and are of importance to, adolescents and adults with cystic fibrosis. This measure will be useful in clinical trials and longitudinal studies.

Ocular signs and symptoms and vitamin A status in patients with cystic fibrosis treated with daily vitamin A supplements

BACKGROUND/AIMS

Patients with cystic fibrosis (CF) may have low plasma vitamin A levels from malabsorption, zinc deficiency, liver disease, or poor compliance with prescribed supplements. In view of the increasing number of adults with CF, many of whom drive cars, it is important to assess vitamin A status. In our centre an attempt has been made to achieve normal levels of fat soluble vitamins by annual estimation of plasma levels and appropriate oral supplementation. This study aimed to determine if this approach prevents vitamin A deficiency and the consequent problems with dark adaptation.

METHODS

The study was conducted at the regional adult and paediatric cystic fibrosis unit and the patients were recruited from there. Dark adaptation studies were conducted at the department of ophthalmology, St James's University Hospital. All patients are regularly seen in the outpatient department by a CF specialist dietitian and have a comprehensive annual dietary assessment. 28 patients had the following investigations: serum retinol, plasma zinc, serum retinol binding protein, liver function tests, dark adaptation, contrast sensitivity, and anterior ocular surface status. 25 age and sex matched controls without CF or ocular pathology were also recruited for the dark adaptation study.

RESULTS

None of the patients had vitamin A deficiency, the median value of serum retinol being 48 microg/dl, range 31-80 microg/dl (normal range 30-80 microg/dl). Dark adaptation was normal in all cases compared with the control group where the mean value was 3.4 log units of threshold luminance (95% confidence interval 2.4-4.0). None of the test group had a value of threshold luminance 2 SD above the mean value for the control group. Eight patients had reduced contrast sensitivity. The median value for serum zinc was 14.2 micromol/ l, range 13-81 micromol/l (normal range 8-23 micromol/l) and the median value for retinol binding protein was 36 mg/l, range 13-81 mg/l (normal range 35-58 mg/l). There was no correlation between dark adaptation and serum retinol, zinc, or retinol binding protein. Two patients had clinical evidence of dry eye.

CONCLUSION

Regular estimates of plasma vitamin A together with appropriate supplementation and expert dietetic review can maintain normal dark adaptation in patients with cystic fibrosis. The occurrence of reduced contrast sensitivity function is well documented but remains an unexplained phenomenon and deserves further study.

Intravenous colistin sulphomethate in acute respiratory exacerbations in adult patients with cystic fibrosis

BACKGROUND

Patients with cystic fibrosis have received more intravenous antibiotic courses as median survival has steadily increased. A number of centres have adopted a policy of regular (three monthly) rather than on demand intravenous antipseudomonal antibiotics. More widespread bacterial antibiotic resistance has resulted from this increased antibiotic use. Most Pseudomonas aeruginosa strains remain fully sensitive to colistin but its use has been resisted owing to concerns about neurotoxicity and nephrotoxicity. A study was carried out to assess the safety and efficacy of intravenous colistin in the treatment of acute respiratory exacerbations in adult patients with cystic fibrosis.

METHODS

Patients with chronic Pseudomonas aeruginosa colonisation who presented with protocol defined respiratory tract exacerbations were randomised to receive treatment for 12 days with either colistin (2 MU tds intravenously) alone or with a second anti-pseudomonal antibiotic. Comparisons of the absolute values of respiratory function tests on days 1, 5, and 12 and of overnight oxygen saturation on days 1 and 12 were the primary outcome measures. Patient's weight, clinical and chest radiographic scores, and peripheral blood markers of inflammation were also documented. The effect of each treatment regimen individually was assessed by the change in clinical measurements from baseline values. Adverse renal effects were monitored by measurement of serum levels of urea and electrolytes, creatinine clearance, and ward urine testing. Neurotoxicity was monitored by direct questioning for symptoms.

RESULTS

Fifty three patients, 18 of whom entered the study twice, were enrolled. The mean forced expiratory volume in one second (FEV1) increased significantly in both groups, mean forced vital capacity (FVC) only with dual therapy. Both groups showed a non-significant increase in overnight oxygen saturation. All patients showed clinical improvement. Thirty seven adverse neurological events (two severe) were reported in 33 patients in the monotherapy group and 37 (none severe) in 36 patients in the dual therapy group. One patient withdrew because of severe weakness and dizziness. All other adverse neurological events were well tolerated and resolved during or shortly after treatment. Significant changes were seen in mean serum urea levels in both groups, but in only four patients to a level above the normal range, and in creatinine clearance in the dual therapy group. At 24 month follow up no long term adverse consequences from intravenous colistin were found in patients who completed the study.

CONCLUSIONS

Intravenous colistin is an effective treatment for Pseudomonas aeruginosa associated pulmonary exacerbations in patients with cystic fibrosis. Assessment of the individual effect of each treatment regimen suggests a greater efficacy when colistin is combined with a second antibiotic to which the pseudomonas shows in vitro sensitivity. Changes in renal function should be monitored.

Conform—A New Concept for the Continuous Extrusion Forming of Metals

The paper describes a new continuous extrusion forming process, for metals, which is particularly applicable in the wire, section, and tube manufacturing fields. The principle of the process is based on the mechanical friction which exists between a billet and its container in conventional extrusion. If the container is rectangular in cross section and three sides are formed as a groove in a rotating wheel, with the fourth side forming a stationary shoe fitting against the outside of the wheel, then rotation of the wheel will carry the billet along with it. If a stop with die orifice is sized to fit the groove and is fixed to the shoe, then as the billet is forced against the die, extrusion can occur. The development of the process from a laboratory bench top model for lead wire, to a powered experimental machine capable of continuously extruding aluminium wire through ratios of 40:1 is described in the paper. The possibilities for future development are discussed and some guide is given to the possible size and capacities of projected machines.