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Biomedical subjects

C F Donner

Publications and source records attributed to C F Donner.

At least 73 records · Page 4Linked to original sources
PubMed1996

Cardiovascular and ventilatory response to isocapnic hypoxia at sea level and at 5,050 m.

To assess the effect of chronic hypoxic conditions on ventilatory, heart rate (HR), and blood pressure (BP) responses to acute progressive isocapnic hypoxia, we studied five healthy Caucasian subjects (3 men and 2 women). Each subject performed one rebreathing test at sea level (SL) and two tests at the Pyramid laboratory at Lobuche, Nepal, at the altitude of 5,050 m, 1 day after arrival (HA1) and after 24 days of sojourn (HA2). The effects of progressive isocapnic hypoxia were tested by using a standard rebreathing technique. BP, electrocardiogram, arterial oxygen saturation, airflow and end-tidal CO2 and O2 were recorded. For each subject, the relationships between arterial oxygen saturation and HR, systolic BP and minute ventilation (VE), respectively, were evaluated. At HA1, the majority of subjects showed a significant increase in VE and BP response and a decrease in HR response to progressive isocapnic hypoxia as compared to SL. At HA2, VE and BP responses further increased, whereas the HR response remained similar to that observed at HA1. A significant relationship between hypoxic ventilatory responses and both systolic and diastolic BP responses to progressive hypoxia was found. No significant correlation was found between hypoxic ventilatory and HR responses.

Adult↗
PubMed1996

Partitioning of inspiratory muscle workload and pressure assistance in ventilator-dependent COPD patients.

To investigate the mechanisms underlying ventilator-dependence in patients with chronic obstructive pulmonary disease (COPD), and to assess the effects of the combination of positive end-expiratory pressure (PEEP) and pressure-support ventilation (PSV) on inspiratory muscle effort, we investigated respiratory mechanics in eight ventilator-dependent COPD patients. The patients' breathing pattern, lung mechanics, diaphragmatic effort (PTPdi), diaphragmatic tension-time index (TTdi), and arterial blood gases were measured during both spontaneous breathing (SB) and ventilatory assistance consisting of PSV alone (15, 20, and 25 cm H2O) and PSV combined with a PEEP of 5 cm H2O (reducing PSV to 10, 15, and 20 cm H2O, respectively, to maintain equivalent inspiratory pressure). The different levels of ventilatory support were delivered in a randomized sequence. Maximal inspiratory (MIP), esophageal (PpImax) and transdiaphragmatic (Pdi(max)) pressures and respiratory drive (P(0.1)) were measured at the beginning of the procedure during SB. We found a high P(0.1) (6.1 +/- 1.7 cm H2O), which seemed to rule out an impairment of respiratory-center output. Apparently, inspiratory muscle strength was compatible with successful weaning (38.5 +/- 8.8, 50.9 +/- 9.7, and 51.8 +/- 9.5 cm H2O for MIP, PPImax and Pdi(max), respectively). However, abnormal respiratory mechanics (particularly an intrinsic positive end-expiratory pressure (PEEPi) of 8.3 +/- 1.9 cm H2O and pulmonary resistance 24.7 +/- 9.5 cm H2O/L/s imposed an excessive load on the inspiratory muscles, as indicated by a high PTPdi (499 +/- 122 cm H2O x s). Increasing levels of PSV progressively and significantly unloaded the patients' inspiratory muscles, although at pressures above 20 cm H2O uncoupling occurred between patient and ventilator respiratory frequency. Application of PEEP during PSV improved ventilatory assistance by further reducing the inspiratory effort (by 17% on average) and by ameliorating patient-ventilator interaction. We conclude that the excessive mechanical load, and in particular the high PEEPi, is the major determinant of ventilator-dependence in COPD patients. Application of PEEP improves the efficiency of PSV in unloading these patients' inspiratory muscles, and can sometimes improve patient-ventilator interaction.

Aged↗
PubMed1996

When is liquid oxygen really needed?

Liquid oxygen is a synonym for portable oxygen, as it combines a big cylinder with an easy-to-fill portable unit, suitable for exercise and use out-doors. The main drawback is its high cost, inherent in a home delivery system, which discouraged many nations from its introduction. The best candidates are patients able to move, who are still active and do not have psychological reticence to its use in public. Transtracheal systems and the advantage of a round the clock treatment and a reduction of flow rate, crucial both to lengthen the autonomy of portable units and to avoid flows higher than 4 L.min-1, which cannot be maintained. Finally, patients on liquid oxygen usually have a better adherence to treatment, mainly compared to those using a concentrator, possibly improving its effectiveness, which is notoriously dependent on total usage per day.

Humans↗
PubMed1995

The effects of doxofylline versus theophylline on sleep architecture in COPD patients.

Theophylline is known to alter sleep architecture because of its affinity to adenosine receptors. One of the consequences of disrupted sleep is impaired cognitive performance. A single-blind, randomized cross-over study of eight male chronic obstructive pulmonary disease (COPD) patients was undertaken to evaluate the effects of theophylline versus doxofylline on sleep architecture. The patients, who were all ex-smokers, had been treated with theophylline. Mean age was 53 +/- 12 yrs, forced expiratory volume in one second (FEV1) 50 +/- 22% predicted and forced vital capacity (FVC) 70 +/- 18% predicted. Following a wash-out period, four patients were given oral slow-release theophylline (T) (300 mg b.i.d.) for one week, followed by a cross-over to doxofylline (D) (400 mg t.i.d.) for a second week. The other four patients were given the drugs in the reverse order. All patients underwent polysomnography at baseline and at the end of each week of treatment. The number of arousals per hour was 5.5 +/- 2.9 at baseline, 9.4 +/- 5.2 during T treatment and 5.4 +/- 4.4 during D treatment. During T treatment, sleep efficiency was 60 +/- 19% vs 75 +/- 13% recorded at baseline trial and 68 +/- 25 recorded during D treatment. Sleep quality, during T treatment, was poorer than at baseline, with a greater increase in the percentage of wakefulness and more stage 2 sleep than at baseline. Slow wave sleep was reduced with both treatments, particularly D. Neither drug affected the arterial oxygen saturation (Sao2) or respiratory rate during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Timing of tracheostomy in neuromuscular patients with chronic respiratory failure.

Noninvasive and invasive mechanical ventilation play a fundamental role in the treatment of neuromuscular patients with respiratory failure. At present no guidelines concerning timing of tracheostomy in neuromuscular patients are available. The authors summarize the factors to be considered in the decision-making process, as illustrated during an international meeting (Tradate, Italy; March 1994) held with the participation of a group of authorities on respiratory care of neuromuscular patients.

Humans↗
PubMed1995

Intraluminal inflammation in the airways of patients with chronic bronchitis after treatment with Ambroxol.

Ambroxol is a mucus-modifying drug with a known ability to stimulate surfactant secretion and inhibit, in vitro, the production of proinflammatory cytokines, neutrophil chemotaxis, and Na+ absorption by the airway epithelium. In dogs inhaling ozone, bronchial hyperreactivity can be inhibited by aerosolized Ambroxol. To verify the possibility of producing anti-inflammatory effects in a clinically relevant condition, 20 patients with chronic bronchitis, randomly divided into two balanced matched groups, were submitted to a 14 day trial with Ambroxol, 150 mg.day-1, or placebo, according to a double-blind design. A bronchoalveolar lavage (BAL) was performed the day before starting treatment (T0) and at the 14th day (T14). The analysis of the cellular and soluble (total proteins, albumin, immunoglobulin G and A (IgG and IgA)) BAL components demonstrated no clear modifications. In particular, neutrophil values from the bronchial aliquot showed a large dispersion, with no significant differences (Ambroxol: T0 = 13.7 +/- 5.2%, T14 = 14.0 +/- 6.8%; placebo: T0 = 3.6 +/- 1.1%, T14 = 5.5 +/- 2.2%). We found a nonsignificant increase of phospholipids in BAL supernatants from Ambroxol-treated patients (2.5 +/- 1.9 vs 3.0 +/- 1.9 micrograms.mg-1 of protein); whilst in the placebo group data before and after treatment were superimposable (2.2 +/- 1.5 vs 2.3 +/- 1.9 micrograms.mg-1 of protein). In conclusion, we have failed to demonstrate that conventional treatment with oral Ambroxol can modify surfactant and BAL cell populations in the airways of patients with chronic bronchitis.

Ambroxol↗
PubMed1995

Long-term nocturnal mechanical ventilation in patients with kyphoscoliosis.

THE AIMS OF OUR STUDY WERE: 1) to evaluate the long-term efficacy of nocturnal IPPV either via tracheostomy (tIPPV) or a nasal mask (nIPPV) as a means to improve alveolar ventilation in patients with chronic severe hypercapnia caused by kyphoscoliosis; and 2) to assess the effect of MV on hospitalizations and life-style. Twenty six patients with kyphoscoliosis in chronic respiratory failure were enrolled in the study. Patients were divided into two groups. The first group comprised 13 subjects who had been clinically stable for at least 1 month (arterial carbon dioxide tension (Pa,CO2) 81 +/- 1.5 kPa (60.8 +/- 10.9 mmHg), arterial oxygen tension (Pa,O2) 7.3 +/- 0.8 kPa (54.6 +/- 6.1 mmHg)). The second group comprised 13 patients who were either suffering or recovering from an episode of acute respiratory insufficiency (Pa,CO2 9.0 +/- 1.8 kPa (67.8 +/- 13.3 mmHg), Pa,O2 6.8 +/- 1.1 kPa (51.2 +/- 8.2 mmHg), breathing supplemental oxygen in seven cases). Patients in the first group were treated with nocturnal IPPV via a nasal mask, whilst those in the second received nocturnal IPPV via tracheostomy. Similar improvements in arterial blood gases (ABGs) were achieved with both methods. Despite the differences in the degree of severity at baseline, after 1 month, ABG values were: Pa,CO2 6.2 +/- 0.6 kPa (46.6 +/- 4.4 mmHg), Pa,O2 9.0 +/- 1.3 kPa (67.5 +/- 9.6 mmHg) (nIPPV patients); Pa,CO2 6.1 +/- 0.9 kPa (46.1 +/- 6.8 mmHg), Pa,O2 9.8 +/- 1.3 kPa (73.6 +/- 9.8 mmHg) (tIPPV patients). After 1 yr, this improvement was still evident. Days of hospitalization were significantly reduced in both groups during the first year of MV. We conclude that both tIPPV and nIPPV are effective in the long-term treatment of respiratory failure in patients with kyphoscoliosis. It would appear from our data that if nIPPV is initiated early in the evolution of chronic respiratory failure in patients with kyphoscoliosis it will delay the necessity to use an invasive technique; however, long-term follow-up studies and larger case series are needed to demonstrate this.

Case-Control Studies↗
PubMed1994

Airways inflammation in subjects with chronic bronchitis who have never smoked.

BACKGROUND: Smoking is the single most common cause of chronic bronchitis but the disease can also occur in non-smokers. Alterations in the lung responsible for the disease, such as oxidant/antioxidant and protease/antiprotease imbalance, have been investigated in smokers. The aim of our study was to evaluate local cellular and soluble factors (albumin, immunoglobulins, proteases, alpha 1-antitrypsin, and transferrin) that may be involved in the development of chronic bronchitis in subjects who have never smoked. METHODS: Sixteen clinically stable patients with chronic bronchitis who had never been smokers were studied and 17 healthy non-smokers served as controls. All subjects underwent bronchoalveolar lavage (BAL). Total and differential cell counts and concentrations of the main proteins (albumin, immunoglobulins, complement fractions, alpha 1-antitrypsin, and transferrin) were measured. Elastase-like activity was assessed in cells and supernatants. To estimate the oxidant burden the release of superoxide anion (O2-) from native cell populations was evaluated. RESULTS: Recovery of BAL fluid was reduced in older individuals in both the chronic bronchitis and control groups. There was no difference in total cell count, but neutrophil percentage count was higher in those with chronic bronchitis (median (range) 3.5 (1.6-14.2)) than in controls (1.3 (0.5-3.7)). These differences were most pronounced in the first recovery, representative of the bronchial lavage. There was no difference in bronchial epithelial cells. Total proteins and albumin levels were comparable and IgG, IgA, IgM, C3, C4, transferrin and alpha 1-antitrypsin values standardised to albumin did not show any significant differences. No differences in elastase-like levels in supernatants were detected. In cell lysates elastase-like activity x 10(7) cells (macrophages+neutrophils) was increased in patients with chronic bronchitis (0.25 (0.06-4.3) compared with controls 0.08 (0.03-0.9) micrograms PPEeq). The release of O2- both at baseline and after opsonised zymosan phagocytosis did not show any differences. Correlation analysis between FEV1 and BAL fluid data showed a negative correlation only with neutrophils/ml. CONCLUSIONS: Clinically stable non-smokers with chronic bronchitis show no alterations of local immune components, oxidant burden, and free elastase-like activity in BAL fluids, while the content of elastase-like activity in phagocytic cells is increased. As in smokers, bronchial neutrophilia is the most significant cellular modification which correlates with the degree of airflow obstruction.

Adult↗
PubMed1994

Physiologic effects of positive end-expiratory pressure and mask pressure support during exacerbations of chronic obstructive pulmonary disease.

To assess physiologic effects of continuous positive airway pressure (CPAP) and positive end-expiratory pressure (PEEP) during noninvasive pressure support ventilation (PSV) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), we measured in seven patients the breathing pattern, lung mechanics, diaphragmatic effort (PTPdi), and arterial blood gases under four conditions: (1) spontaneous breathing (SB); (2) CPAP; (3) PSV of 10 cm H2O; and (4) PSV plus PEEP (PEEP + PSV). CPAP and PEEP were set between 80 and 90% of dynamic intrinsic PEEP (PEEPidyn) measured during SB and PSV, respectively. PEEPidyn was obtained (1) from the decrease in pleural pressure (delta Ppl) preceding inspiration, and (2) subtracting the fall in gastric pressure (delta Pga) caused by relaxation of the abdominal muscles from the delta Ppl decrease. Abdominal muscle activity made PEEPidyn overestimated in almost all instances (p < 0.0001). PSV increased minute ventilation, improved gas exchange, and decreased PTPdi. PEEP added to PSV, likewise CPAP compared with SB, further significantly decreased the diaphragmatic effort (PTPdi went from 322 +/- 111 to 203 +/- 63 cm H2O.s) by counterbalancing PEEPidyn, which went from 5.4 +/- 4.0 to 3.1 +/- 2.3 cm H2O. These data support the use of low levels of PEEP (80 to 90% of PEEPidyn) to treat acute exacerbation of COPD by means of mask PSV.

Acute Disease↗
PubMed1994

Intermediate respiratory care unit: admission criteria.

Intensive care unit (ICU) management of patients on partial ventilatory support is very costly. We opened an intermediate respiratory care unit (RCU), with the aim of providing cost beneficial in-hospital and home care for patients who require mechanical ventilation for at least 8 h.day-1. Prior to admission to an intermediate RCU, it is mandatory to take into consideration not only the patient's overall health status but also his or her prognosis, and rehabilitation chances and environmental factors have to be evaluated.

Humans↗
PubMed1994

Intermediate respiratory care unit: rehabilitation.

The ventilator assisted individual (VAI) represents a complex set of medical and social issues that call for the involvement of multiple interest groups. The success of treatment for VAI depends on many factors. These include: appropriate selection of patients for care outside the hospital, clinical and physiological stability of patients, patient and family motivation, and their ability to learn. Assisted ventilation in chronic respiratory failure secondary to chest-wall deformities and neuromuscular disease has shown promising results. Less satisfactory have been those reported in patients with chronic obstructive pulmonary disease (COPD). COPD candidates for chronic mechanical ventilation should be carefully selected. Patients should not be discharged on ventilators to nonhospital environments before they are clinically stable. It is also crucial to rule out other medical diseases that could interfere with successful discharge and home-care. Discharge planning requires the support and involvement of the physicians, nurses, and other allied health professionals. Education is of vital importance and, as such, needs to begin early in the patient's hospital stay. A basic checklist of skills that the VAI and the family will need to know should be developed, as well as an individual rehabilitation programme planned according to the patient's primary problem, with realistic short- and long-term goals. The aim is to restore and maintain the best possible quality of life for the individual.

Health Education↗
PubMed1994

Selection criteria for exercise training in patients with COPD.

The physical performance of patients with chronic obstructive pulmonary disease (COPD) is limited mainly by pathophysiological derangements of the ventilatory system. Thus, the exercise performance can be ameliorated by increasing the level of ventilation that they can sustain, or by reducing the ventilatory requirement for a given level of activity. Almost all studies have yielded negative results in COPD patients, in terms of exercise training having the ability to improve VEmax. The only way to reduce the ventilatory requirement is to reduce CO2 output. Lower levels of lactate result in less non-metabolic CO2 produced by bicarbonate buffering. This is the likely mechanism responsible for a lower ventilatory requirement for work rates above the pre-training anaerobic threshold. We specifically wished to determine, whether a program of intensity, frequency and duration known capable of producing a physiologic training effect in healthy subjects, would do so in COPD patients. Further, we sought to determine, whether exercise training at a work rate associated with lactic acidosis is more effective in inducing a training effect in COPD patients than a work rate not associated with lactic acidosis. Nineteen COPD patients were selected and performed an incremental test as well as two square wave tests at a low and a high work rate. Identical tests were performed after an 8-week program of cycle ergometer training either for 45 min/day at a high work rate or for a proportionally longer time at a low work rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1994

Cardiopulmonary exercise testing in interstitial lung disease.

Interstitial lung disease (ILD) can determine severe lung function impairment both at rest and during exercise. Usually, resting measurements of lung and cardiac function give enough information on the degree of the disease. Thus, exercise testing should be reserved only for particular situations such as presence at the same time of cardiac and respiratory involvement, symptomatic patients with normal spirometry, and to check the response to therapy. A better understanding of the pathophysiology and cardiorespiratory consequences of ILD can give an important contribution in improving methods of exercise testing to assess disability. In this perspective, we analyze the factors limiting exercise performance: the progressive hypoxemia that appears or is worsened by exertion; the ventilatory abnormalities that lead to a rapid shallow breathing pattern with a VE that reach the MVV; and the cardiovascular limitation with low maximum heart rate, low cardiac output and high PVR and PAP.

Exercise Test↗
PubMed1994

Preventive treatment of chronic bronchitis: a meta-analysis of clinical trials with a bacterial extract (OM-85 BV) and a cost-effectiveness analysis.

Chronic bronchitis is a lifelong disease with significant effects on the patient and on the costs to health insurance institutions. Acute exacerbations in chronic bronchitic patients may have a negative impact on patients' quality of life and on the progression of the disease, particularly in more severe patients. The clinical efficacy of the immunoactive bacterial extract OM-85 BV has been shown in several clinical trials, a cost-effectiveness evaluation (CEA) of its use in chronic bronchitic patients has not been fulfilled so far. In this study a meta-analysis on the preventive treatment of acute exacerbations with OM-85 BV and a CEA, focusing on direct costs only, was performed. The meta-analysis showed a mean value of 0.6 prevented acute exacerbations per 6 months per patient, and a reduction of 9 days in antibiotic treatment per 6 months per patient. CEA evaluated the different cost elements. The mean direct cost (consultations, antibiotics, etc.) for the treatment of 1 acute exacerbation in chronic bronchitic patients was calculated as 143, 459 Lira. Thus for 0.6 prevented acute exacerbations per 6 months per patient a reduction in cost of 86,075 Lira (0.6-143,459) could be expected. The additional costs for the preventive treatment with OM-85 BV, based on prices for Italy, are 34,980 Lira per patient per 6 months. In conclusion, the effective cost savings per patient per 6 months are 51, 095 Lira. The sensitivity analysis revealed only one critical parameter, i.e. the clinical effectiveness of OM-85 BV. Even assuming 0.3 prevented exacerbations per 6 months per patient, the preventive treatment still proved to be cost effective.

Adjuvants, Immunologic↗
PubMed1994

Selection and evaluation of recipients for heart-lung and lung transplantation: the Niguarda Hospital experience.

Between January 1989 and February 1993, 52 patients were evaluated at Niguarda Hospital for lung or heart and lung transplantation. Of the 35 that entered the waiting list, a total of 19 were transplanted (14 at other institutes before our surgical programme became operative, and 5 at our hospital). Recipient selection and evaluation criteria, and timing of transplantation in the different diseases are discussed.

Contraindications↗