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Biomedical subjects

H T Folgering

Publications and source records attributed to H T Folgering.

At least 55 records · Page 3Linked to original sources
PubMed1996

Nocturnal saturation improves by target-flow inspiratory muscle training in patients with COPD.

Nocturnal desaturations during rapid eye movement (REM) sleep, caused by nonobstructive hypoventilation, occur frequently in patients with chronic obstructive pulmonary disease (COPD). This is partly caused by decreased activity of the intercostal and accessory muscles due to a lower motor command. The diaphragm has to compensate for the diminished activity of these muscles during REM sleep. However, in patients with COPD strength and endurance of the diaphragm may be affected by its unfavorable position on the length-tension curve because of hyperinflation. The aim of this study was to establish the causal relationship between respiratory muscle function and nocturnal saturation in patients with COPD. We hypothesized that target-flow inspiratory muscle training (TF-IMT) would improve nocturnal saturation. In 20 patients with stable COPD (FEV1 35.5 +/- 14.1% of predicted) and a mean nocturnal saturation below 92% we measured maximal inspiratory pressure (PImax), transdiaphragmatic pressure (Pdi), maximal sustainable inspiratory pressure (SIPmax), endurance time, and nocturnal saturation in Weeks 0, 4, and 10. During these 10 wk 10 patients underwent TF-IMT at 60% of PImax and 10 control patients received sham TF-IMT at 10% of PImax. PImax, Pdi, SIPmax, and the endurance time as well as the nocturnal saturation improved significantly in the 60% training group (by 3.0 +/- 1.5 kPa, 3.4 +/- 1.9 kPa, 1.5 +/- 1.4 kPa, 189 +/- 149 s, and 1.9 +/- 2.2%, respectively), whereas no changes occurred in the sham training group. Also, significant correlations were observed between the changes in Pdi, SIPmax, and endurance time on the one hand and the change in nocturnal saturation on the other. We conclude that TF-IMT improves the nocturnal saturation in patients with severe COPD by increasing respiratory muscle strength and endurance.

Data Interpretation, Statistical↗
PubMed1996

Effects of different treatment regimens of methylprednisolone on rat diaphragm contractility, immunohistochemistry and biochemistry.

Systemic corticosteroid therapy may affect diaphragm structure and function. We postulated that functional, immunohistochemical and biochemical characteristics of rat diaphragm were less affected by alternate-day methylprednisolone (MP) administration, and more by repeated bursts of MP, in comparison to daily s.c MP. Sixty adult rats were randomized into four groups: saline s.c.; MP continuously (MP-C), 1 mg.kg-1 daily, MP alternate-day therapy (MP-A), 2 mg.kg-1 every other day; or MP in bursts (MP-B), MP 2 mg.kg-1 daily for 2 weeks, saline for 4 weeks, MP 2 mg.kg-1 daily for 2 weeks. The total treatment period was 8 weeks. Contractile properties of isolated diaphragm strips were measured. Antibodies reactive with type I, IIa, IIx and IIb myosin heavy chains were used for immunohistochemical analysis. Biochemical evaluation included markers of fast energy supply, glycogenolytic activity, beta-oxidation capacity and oxidative capacity. The force-frequency curve was depressed in all MP groups. Fibre type I, IIx and IIb cross-sectional area (CSA) decreased in all MP groups. Burst therapy decreased the contribution of type IIb fibres to total diaphragm muscle area. MP-A affected glycogenolytic activity less than MP-C. Burst MP therapy reduced creatine kinase (CK) activity and beta-oxidation capacity compared to MP-C. Oxidative capacity was increased in all MP groups. In conclusion, although the methylprednisolone treatment regimens affected diaphragm muscle morphology and bioenergetic enzyme activities in different ways, force generation decreased in all methylprednisolone treated groups to the same extent.

Analysis of Variance↗
PubMed1995

Visual attention in patients with chronic obstructive pulmonary disease.

The selective visual attention of 39 patients with chronic obstructive pulmonary disease (COPD) was measured by the Bourdon-Vos test and compared with the attention performance of 38 healthy controls of the same age range. The correlation between the attention of the COPD patients and day- and night-time parameters was determined. Furthermore, in 44 other COPD patients with daytime hypoxaemia, the effect of one night of oxygen supplementation and of a 7-day treatment with two respiratory stimulants (chlormadinone acetate) (CMA) or acetazolamide (ACET) on attention performance was studied. The results showed that the attention performance of COPD patients was lower than that of controls. Significant correlations were found between the mean line time (attention parameter) and the following parameters: age, inspiratory vital capacity (IVC), hypercapnic ventilatory response (HCVR), daytime arterial oxygen saturation (SaO2), daytime arterial oxygen pressure (PaO2), daytime arterial carbon dioxide pressure (PaCO2), mean nocturnal SaO2, lowest nocturnal SaO2 and the standard deviation of the mean nocturnal SaO2. Multiple linear regression analysis showed that, apart from age, only the nadir of the nocturnal SaO2 contributed to the prediction of the attention. No clinically important short-term effect of oxygen or respiratory stimulating therapy on the attention performance was found.

Acetazolamide↗
PubMed1995

Vestibular hyperreactivity and hyperventilation after whiplash injury.

Vestibular, oculomotor and respiratory tests were performed on 32 patients after whiplash injury caused by a rear-end car collision. Oculomotor functions were generally normal. The cervico-ocular reflex was usually absent or displayed the low gain typical of normal subjects. There was no nystagmic response to static neck torsion. The vestibulo-ocular reflex showed vestibular hyperreactivity (VH) in a significantly large number of cases (n = 17; 53%). The respiratory test results were also typical of the hyperventilation syndrome (HVS) in a significantly large number of cases (n = 12; 38%). The findings of VH and the HVS were not significantly correlated within the patient group. However, the combination of VH and the HVS occurred significantly more often (n = 7; 22%) than could be accounted for by combined false positivity. Most of the significant findings were due to high relative frequencies in the women: 11 out of the 17 women (65%) showed VH, 8 (47%) had the HVS and 5 (29%) showed a combination of VH and the HVS. The findings were not correlated with the patient's age or the time interval between the accident and the examination. VH might have been the result of plastic adaptation to limited head mobility secondary to neck pain. Behavioural and emotional distress might offer alternative explanations for both VH and the HVS.

Accidents, Traffic↗
PubMed1995

Nocturnal saturation and respiratory muscle function in patients with chronic obstructive pulmonary disease.

BACKGROUND: Nocturnal desaturations, mainly caused by hypoventilation, occur frequently in patients with chronic obstructive pulmonary disease (COPD). Daytime arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2) appear to predict which patients will desaturate at night. It is unknown if respiratory muscle strength, which may be decreased in these patients, plays an additional part. METHODS: Polysomnography, maximal respiratory pressures, lung function, and arterial blood gas tensions were measured in 34 patients with COPD (mean (SD) forced expiratory volume in one second (FEV1) 41.7 (19.9)% pred). RESULTS: Significant correlations were found between the mean nocturnal arterial oxygen saturation and maximal inspiratory mouth pressure (r = 0.65), maximal inspiratory transdiaphragmatic pressure (r = 0.53), FEV1 (r = 0.61), transfer coefficient (KCO) (r = 0.38), arterial oxygen saturation (SaO2) (r = 0.75), and PaCO2 (r = -0.44). Multiple regression analysis showed that 75% of the variance in nocturnal SaO2 (70%) and FEV1 (5%). CONCLUSION: Inspiratory muscle strength and nocturnal saturation data are correlated, but daytime SaO2 and FEV1 remain the most important predictors of nocturnal saturation.

Aged↗
PubMed1995

Predictors for nocturnal hypoxaemia (mean SaO2 < 90%) in normoxic and mildly hypoxic patients with COPD.

Detection of nocturnal hypoxaemia, defined as a mean arterial oxygen saturation below 90%, in normoxic or mildly hypoxic chronic obstructive pulmonary disease (COPD) patients seems clinically relevant, since this feature may precede pulmonary hypertension. Nocturnal studies are expensive and time-consuming procedures. The current study investigates to what extent it is possible to predict nocturnal hypoxaemia from daytime parameters. Forty two COPD patients with a daytime arterial oxygen tension (PaO2) above 8 kPa participated. Nocturnal oxygenation, daytime blood gas values, and ventilatory responses to hypercapnia were measured. In 10 patients, enough desaturations occurred to qualify as nocturnal hypoxaemia. They had a significantly lower daytime PaO2 value, and a lower steady-state hypercapnic ventilatory response. They also smoked more often, and complained about daytime sleepiness. Multiple linear regression analysis demonstrated that daytime PaO2 (32%) was the best independent predictor. Sleepiness (12%), and number of cigarettes smoked (5%) also contributed independently, but in a minor way. Patients with a high daytime PaO2 (> 11 kPa) did not develop nocturnal hypoxaemia. The hypercapnic ventilatory response was used to distinguish nocturnal hypoxaemic from normoxaemic patients. Only patients with a low response (< 3.5 l.min-1.kPa-1) appeared to run a risk of developing nocturnal hypoxaemia. The sensitivity of this test was 80%, and the specificity 70%. It is concluded that daytime PaO2, hypercapnic ventilatory response and sleepiness are helpful in predicting nocturnal hypoxaemia.

Aged↗
PubMed1995

Histamine-induced end-tidal inspiratory activity and lung receptors in cats.

Hyperinflation in acute asthma has been associated with inspiratory muscle activity, which persist during expiration. The main objective of the present study was to evaluate the role of rapidly adapting receptors (RARs), slowly adapting receptors (SARs) and C-fibre endings in generating end-tidal inspiratory activity (ETIA). ETIA was induced by intravenous administration of histamine and continuous negative airway pressure (CNAP) in anaesthetized, spontaneously breathing cats. To differentiate between reflex activities from the three types of lung receptors, both vagus nerves were cooled to eight different temperatures (Tvg) between 4 and 37 degrees C. It is known that CNAP stimulates RARs and inhibits SARs. Histamine was used to stimulate RARs, and this was combined with continuous positive airway pressure (CPAP) to further stimulate SARs. ETIA was evoked in the diaphragm and in parasternal intercostal muscles by both stimuli (histamine and CNAP) in 8 out of 18 cats. After vagotomy, neither histamine nor CNAP evoked ETIA any more. At Tvg = 37 degrees C, CPAP suppressed histamine-induced ETIA; whereas, this suppression was diminished at Tvg between 14 and 8 degrees C. ETIA sharply declined for Tvg between 8 degrees and 4 degrees C, and at Tvg = 4 degrees C ETIA had virtually disappeared. At Tvg = 37 degrees and 22 degrees C values of ETIA during CNAP were larger than those in response to histamine; whereas, at Tvg = 10 degrees C comparable ETIA values were obtained. It was shown that ETIA is a vagal reflex activity in which C-fibre endings are not involved. Histamine-induced ETIA originates from stimulation of RARs, and is inhibited by stimulation of SARs. Mechanical stimulation of RARs is a forceful stimulus to induce ETIA. This suggests that hyperinflation in acute asthma might be due, at least in part, to ETIA resulting from an imbalance between SAR and RAR activity.

Animals↗
PubMed1995

Hyperactive VOR and hyperventilation after whiplash injury.

Otoneurological and respiratory tests were performed on 32 patients after whiplash injury caused by a rear-end car collision. Oculomotor and cervico-ocular test results were generally normal. In a significantly large number of case, the vestibulo-ocular reflex (VOR) was hyperactive (n = 17; 53%) and the respiratory test results were typical of the hyperventilation syndrome (HVS) (n = 12; 38%). Hyperactive VOR and the HVS occurred significantly more often in combination (n = 7; 22%) than could be accounted for by combined false positivity. Most of the significant findings were due to high relative frequencies in the women. The hyperactive VOR might have been the result of plastic adaptation to limited head mobility secondary to neck pain. Behavioural and emotional distress might offer alternative explanations for both the hyperactive VOR and HVS.

Adult↗
PubMed1995

Pressure-volume analysis of the lung with an exponential and linear-exponential model in asthma and COPD. Dutch CNSLD Study Group.

The prevalence of abnormalities in lung elasticity in patients with asthma or chronic obstructive pulmonary disease (COPD) is still unclear. This might be due to uncertainties concerning the method of analysis of quasistatic deflation lung pressure-volume curves. Pressure-volume curves were obtained in 99 patients with moderately severe asthma or COPD. These patients were a subgroup from a Dutch multicentre trial; the entire group was selected on the basis of a moderately lowered % predicted forced expiratory volume in one second (FEV1), and a provocative concentration of histamine producing a 20% decrease in FEV1 (PC20) < 8 mg.mL-1 obtained with the 2 min tidal breathing technique. The curves were fitted with an exponential (E) model and an exponential model which took the linear appearance in the mid vital capacity range into account (linear-exponential (LE)). The linear-exponential model showed a markedly better fit ability, yielding additional parameters, such as the compliance at functional residual capacity (FRC) level as slope of the linear part (b), and the volume at which the linear part changed into the exponential part of the curve (transition volume (Vtr)). Vtr (mean value Vtr/total lung capacity (TLC) = 0.79 (SD 0.07)) showed a close positive linear correlation with obstruction and hyperinflation variables, which might be due to airway closure, already starting at elevated lung volumes. The exponential shape factor K was closely correlated with b and mean values (K = 1.32 (SD 0.05) kPa-1; b = 2.96 (SD 1.16) L,kPa-1) and the relationship with age was comparable with data reported in healthy individuals. The shape factor of the linear-exponential fit showed no correlation with any elasticity related variable. Neither the elastic recoil at 90% TLC, as obtained from the linear-exponential fit, nor its relationship with age were significantly different from healthy individuals. We conclude that, for a more accurate description of the lung pressure-volume curve, a linear-exponential fit is preferable to an exponential model. However, the physiological relevance of the shape parameter (KLE) is still unclear. These results indicate that patients with moderately severe asthma or COPD had, on average, no appreciable loss of elastic lung recoil as compared with healthy individuals.

Adolescent↗
PubMed1994

Oscillatory respiratory impedance and lung tissue compliance.

The respiratory impedance was measured by means of the forced oscillation technique (Landser et al.) and the lung tissue compliance was measured with an oesophageal balloon in 30 patients with a wide range of values of lung tissue compliance. According to the model of respiratory impedance of Nagels et al. it is unlikely that the impedance data are markedly affected by the lung tissue compliance. This hypothesis has not been clinically tested yet. The semistatic compliance (Css) or specific compliance (Cspec) were not statistically correlated with any of the impedance data. Consequently the oscillatory respiratory measurements are not systematically influenced by the compliance of the lung tissue during quiet breathing. However, the dynamic compliance and the frequency dependence of the compliance showed a low but significant correlation with the reactance and resonant frequency (varying from r = 0.41, P < 0.05 to r = -0.54, P < 0.01). A significant correlation was found between the frequency dependence of the lung tissue compliance and the frequency dependence of the oscillatory resistance, both being indicative of peripheral airway obstruction (varying from r = -0.54, P < 0.01 for the whole group, to r = -0.75, P < 0.001 for 15 patients with severe peripheral airway obstruction: mean (SD) FEV1 59.5 (24.8)% pred, mean (SD) MEF50 30.9 (25.8)% pred.

Adult↗
PubMed1994

Effects of body position, hyperinflation, and blood gas tensions on maximal respiratory pressures in patients with chronic obstructive pulmonary disease.

BACKGROUND: Inspiratory muscle strength in patients with chronic obstructive pulmonary disease (COPD) can be affected by mechanical factors which influence the length of the diaphragm, and by non-mechanical factors. The aim of the present study was to evaluate firstly the effects of body position on respiratory pressures and, secondly, to determine the relative contribution of age, body mass index (BMI), lung volumes, and arterial blood gas tensions to respiratory muscle strength. METHODS: Thirty male patients with stable COPD (mean FEV1 40.4% predicted) participated in the study. Maximal inspiratory and expiratory mouth pressures (PImax, PEmax) and maximal inspiratory transdiaphragmatic pressures (PDI) in the sitting and supine position, lung function, and arterial blood gas tensions were measured. RESULTS: Mean (SD) PImax in the sitting position was higher than in the supine position (7.1(2.3)kPa v 6.4(2.2)kPa respectively). In contrast, PDI in the sitting position was lower than in the supine position (10.0(3.5)kPa v 10.8(3.7)kPa respectively). PEmax was higher in the sitting position (9.3(3.0)kPa) than in the supine position (8.7(2.8)kPa). Significant correlations were found between inspiratory muscle strength on the one hand, and lung function parameters, BMI, and arterial blood gas tensions on the other. CONCLUSIONS: Inspiratory muscle strength in patients with COPD is influenced by mechanical factors (body position, lung volumes) and non-mechanical factors (BMI, FEV1, and blood gases). PImax and PEmax are lower in the supine position while, in contrast to healthy subjects, PDI is higher in the supine position than in the sitting position.

Aged↗
PubMed1994

Continuous negative airway pressure increases tonic activity in diaphragm and intercostal muscles in humans.

The main objective of the present study was to quantify the increase in tonic inspiratory activity (delta TIA) in response to continuous negative airway pressure (CNAP) in humans. TIA represents the activity in inspiratory muscles at the end of expiration. In 20 subjects, electromyograms (EMGs) were recorded from the diaphragm and parasternal intercostal muscles (ICM) with surface electrodes during control and at three different levels of CNAP (-0.3, -0.6, and -0.9 kPa; 1 kPa approximately 10 cmH2O). From these recordings we determined delta TIA and the amplitudes of phasic EMG activities (EMGphas) during CNAP and control. To evaluate the effects of CNAP on functional residual capacity (FRC), respiratory frequency, tidal volume, and minute ventilation, the subjects were connected to a closed breathing circuit. When the pressure at the airway opening was -0.9 kPa, mean values of delta TIA were 53 and 49% of control EMGphas for the diaphragm and ICM, respectively. In addition, EMGphas at airway opening pressure of -0.9 kPa had increased to 195 and 162% of control EMGphas for the diaphragm and ICM, respectively. The concomitant decrease in FRC was on average 18.7% of predicted FRC. Minute ventilation had increased significantly (P < 0.05) at all levels of CNAP compared with control. We conclude that CNAP is a forceful stimulus to increase TIA in humans in both the diaphragm and the ICM.

Adolescent↗
PubMed1994

Effects of chlormadinone acetate, acetazolamide and oxygen on awake and asleep gas exchange in patients with chronic obstructive pulmonary disease (COPD).

The purpose of this study was to assess the short-term effects of chlormadinone acetate (CMA), a synthetic progestogen, acetazolamide (ACET) and oxygen on awake and asleep blood gas values. The study was conducted according to a randomized, double-blind and placebo-controlled design in 53 hypoxaemic patients with chronic obstructive pulmonary disease. On the first two consecutive nights, all patients received either room air or oxygen, via a nasal cannula, in random order. They then received either CMA (25 mg), ACET (250 mg) or placebo twice a day, all in identical capsules. On the third study night, after one week of drug treatment, the patients were tested breathing room air. CMA and ACET therapy decreased mean daytime arterial carbon dioxide tension (PaCO2) by 0.7 and 0.5 kPa, respectively, and night-time end-tidal carbon dioxide tension (PETCO2) by 0.5 and 0.3 kPa, respectively. Supplemental oxygen caused increased CO2 retention during the day and night (0.6 and 0.3 kPa, respectively. Daytime arterial oxygen tension (PaO2) increased to the same extent during ACET (1.9 kPa) and oxygen (2.5 kPa). Asleep oxygen saturation improved most with oxygen supplementation (7%), although ACET also caused significant improvement (4%). CMA administration had virtually no effect on mean awake and asleep hypoxaemia. ACET therapy significantly improved subjective sleep quality. On CMA, minute ventilation increased in association with an augmentation of the hypercapnic ventilatory response. ACET treatment increased both hypercapnic and hypoxic ventilatory responses. We conclude from the group of patients with COPD studied, that the short-term effects of ACET treatment on gas exchange compare favourably with those of CMA. Oxygen therapy improves oxygenation slightly more than ACET, but aggravates CO2 retention.

Acetazolamide↗
PubMed1994

Pulmonary rehabilitation at moderate altitude: a 1-year follow-up.

BACKGROUND: In order to evaluate a pulmonary rehabilitation program (PRP) at moderate altitude (1560 m) 62 patients with obstructive lung disease were asked to participate; 37 patients completed a 1-year follow-up at sea level, and 25 patients dropped out. The exercise training program lasted for 10 weeks and consisted of a cycling and running program of 20 min daily, 5 days a week. METHODS: Incremental exercise testing, spirometry and histamine provocation tests were performed at sea level before the PRP, on admission to the Dutch Asthma Centre, Davos, after 5 weeks of exercise training, at discharge from the Centre and 6 and 12 months after discharge at sea level. RESULTS: The PRP led to an increase in exercise capacity of the 37 patients who also completed the follow-up as reflected by an increase in Wmax (from 104 +/- 44 watt on admission to 150 +/- 8 at discharge, p < 0.001). HRmax (145 +/- 19/min to 151 +/- 21, p < 0.001), Wmax/HR (0.71 +/- 0.26 watt/beat/min to 0.99 +/- 0.29, p < 0.001), VO2max (1.4 +/- 0.4 l/min to 1.9 +/- 0.6, p < 0.001) and VEmax (49 +/- 18 l/min to 78 +/- 24, p < 0.001) measured at discharge from the Dutch Asthma Centre after the PRP were significantly higher than before the PRP at incremental exercise testing. The group of 25 patients who dropped out showed corresponding improvements in these parameters after the PRP in Davos. The 37 patients who completed the follow-up showed at incremental exercise testing 1 year after the PRP that only two of these parameters were still significantly elevated: VO2max 1.8 +/- 0.6 (p < 0.001) and VEmax 61 +/- 21 (p < 0.001). One year after the PRP arterial PCO2 values at maximum exercise were significantly lower (5.2 +/- 0.8 kPa, p < 0.05) than the baseline values (5.5 +/- 0.9 kPa). CONCLUSIONS: PRP at moderate altitude results in an increase of exercise tolerance in patients with asthma or COPD, but significant long-term effects are few.

Adult↗