Biomedical subjects

C L Lafortuna

Publications and source records attributed to C L Lafortuna.

At least 37 records · Page 2Linked to original sources

PubMed2003

Effects of short-term, integrated body mass reduction program on maximal oxygen consumption and anaerobic alactic performance in obese subjects.

The study investigated the effect of a short-term (3-week) body mass reduction program, combining energy-restricted diet, nutritional education, psychological counselling and aerobic exercise training (DEP-AT) on maximal oxygen consumption (VO2max) and anaerobic alactic performance evaluated with different techniques in obese patients (grade II and III). Fifty-three (14 males, 39 females) obese subjects [average +/- SD body mass index (BMI): 41.6 +/- 4.2 kg/m2] were tested before and after the DEP-AT program characterised by a daily conditioning protocol of aerobic exercise on cycloergometer, treadmill and armergometer for a total duration of 35 min at an intensity corresponding to 50% of individual VO2max during the first week of the program and at 60% in the following 2 weeks. VO2max was determined with the cycloergometric indirect method. Short-term alactic anaerobic performance was evaluated with: a) jumping test (5 consecutive jumps with maximal effort, Bosco technique), b) short sprint running test (8m), and c) stair climbing test (modified Margaria test). The DEP-AT program induced a significant weight loss (-4.57 +/- 1.26%, p < 0.001) and a significant VO2max increase (14.1 +/- 20.5%, p < 0.001). After the DEP-AT program, lower limb alactic anaerobic power output, calculated on a per kg body mass basis, increased significantly both in jumping and in stair climbing (20.1 +/- 24.8%, p < 0.001 and 13.5 +/- 19.75%, p < 0.001, respectively), as well as average horizontal velocity during short sprinting (7.2 +/- 17.6%, p < 0.01). Power output was a major determinant of the motor performance, being significantly correlated with: a) vertical displacement of the centre of gravity (R2 = 0.884, p < 0.001) in jumping test, b) vertical velocity (R2 = 0.348, p < 0.001) in stair climbing test, and c) horizontal velocity (R2 = 0.394, p < 0.001) in short running test. In conclusion, short-term DEP-AT program induces significant improvements in both aerobic capabilities and anaerobic performance, possibly through the combination of a number of contributory mechanisms, such as exercise-mediated training, shift in the balance between parasympathetic and sympathetic activity, a weight-loss dependent shift toward a more favourable region of the muscle power-velocity curve, acquisition of a certain degree of motor skill during the conditioning program, improvement of self-esteem and motivation.

Adolescent↗

PubMed2003

Short-term effects of two integrated, non-pharmacological body weight reduction programs on coronary heart disease risk factors in young obese patients.

In order to evaluate the short-term effects (3 weeks) on selected coronary heart disease (CHD) risk factors, 90 obese in-patients (body mass index, BMI, > or = 35 kg/m2 received a same low-calorie diet (1200-1800 kcal/day), nutritional education and psychological counselling, and were randomly assigned to either a non-specific, high-volume, low-intensity exercise training program (NET), or to an individualised, low-volume and high-intensity exercise training program (IET), for 5 days/week for 3 weeks. NET and IET programs lead to a significant reduction in blood glucose (6.2 and 7.7% respectively), total cholesterol (17.3%, 12.3%), HDL-cholesterol (13.7%, 15.2%), systolic (8.9%, 5.3%) and diastolic resting blood pressure (10.6%, 3.3%). Total CHD scores were also significantly improved (38.1%, 33.1%). The changes occurred with a relatively moderate decrease in body weight (4.2%, 4.4%) and with still elevated BMI values (41.6 kg/m2). Although IET, compared to NET program, induced smaller reductions of blood pressure, it requires 30% daily training period and may possibly enhance long-term patient compliance.

Adolescent↗

PubMed2002

Lower limb alactic anaerobic power output assessed with different techniques in morbid obesity.

Short-term alactic anaerobic performance in jumping (5 consecutive jumps with maximal effort), sprint running (8 m) and stair climbing (modified Margaria test) were measured in 75 obese subjects (BMI: 40.3+/-5.0 kg/m2) and in 36 lean control subjects (BMI: 22.4+/-3.2 kg/m2) of the same age and gender distribution. The results show that obese subjects attained a significantly lower specific (per unit body mass) power output both in jumping (W(spec,j); p<0.001) and stair climbing (W(spec,s); p<0.001) and run at a significantly lower average velocity (v; p<0.001) during sprinting. In spite of the different motor skillfulness required to accomplish the jumping and climbing tests, W(spec,s) (and hence the vertical velocity in climbing, v(v)) was closely correlated with W(spec,j) (R2=0.427, p<0.001). In jumping, although the average force during the positive work phase was significantly higher in obese subjects (p<0.001), no difference between the 2 groups was detected in absolute power. In stair climbing the absolute power output of obese resulted significantly higher (18%) than that of lean controls (p<0.001). In sprint running, the lower average horizontal velocity attained by obese subjects also entailed a different locomotion pattern with shorter step length (L(s); p<0.001), lower frequency (p<0.001) and longer foot contact time with ground (T(c,r); p<0.001). W(spec,j) seems to be a determinant of the poorer motor performance of obese, being significantly correlated with: I) the vertical displacement of the centre of gravity (R2=0.853, p<0.001) in jumping; II) with v(v) in stair climbing; and III) with T(c,r) (R2=0.492, p<0.001), L(s) (R2=0.266, p<0.001) and v (R2=0.454, p<0.001) in sprinting. The results suggest that obese individuals, although partially hampered in kinetic movements, largely rely on their effective specific power output to perform complex anaerobic tasks, and they suffer from the disproportionate excess of inert mass of fat. Furthermore, in view of the sedentary style of life and the consequent degree of muscle de-conditioning accompanying this condition, it may prove useful to implement rehabilitation programs for obesity with effective power training protocols.

Adult↗

PubMed2002

The impact of gender, body dimension and body composition on hand-grip strength in healthy children.

Maximum hand-grip (HG) strength, body composition and main anthropometric variables were evaluated in 278 children with normal weight and growth, aged 5-15 yr divided into 3 age groups: group 1, age+/-SD: 7.6+/-0.9 yr 7.6+/-0.9 SD (Tanner stage 1); group 2, age: 10.8+/-0.7 yr (Tanner stage: 2-3); group 3, age: 13.2+/-0.9 yr (Tanner stage: 4-5). Weight, height, body surface area (BSA), BMI, percent body fat (BF) and fat free mass (FFM) increased progressively and significantly from the younger to the older age group. A significant difference between genders was detected only for BF and FFM, females having a higher fat mass and a lower FFM compared to males. Most children were right-handed (91%). In either genders, a curvilinear relation was detected between HG strength and age, with best fit for the dominant (d) hand given by the equations: dHG=5.891 *10(0.051) age, r2=0.986, p<0.001 in males and dHG=6.163 *10(0.045) age r2=0.973, p<0.001 in females. The increase in HG strength after 11 yr appears to be steeper in males as compared with that found in females. In both d and non-dominant (nd) hand, a significant difference in HG strength was detected between males and females, the average difference being about 10% at all ages. For both genders, nd hand was significantly weaker than d hand in the older age groups (2 and 3), but not in the younger group 1. Age and gender-dependent differences in HG strength (but not differences between d and nd hand) disappear if HG strength is normalized for FFM. Thus, in general, dHG strength normalized for FFM resulted on average to be 0.67+/-0.11 kg/kg. A multiple linear regression analysis indicated that HG was positively correlated with BMI, BSA, stature, stature2 and FFM (p<0.001 for all correlations) without differences between genders, while a negative correlation was found between HG strength and %BF. The most significant correlation was found between HG strength and FFM, without any significant difference between genders, so that the overall equation describing the line for the d hand was: dHG strength= 2.32+0.63 FFM, r2=0.72, p<0.001. In conclusion, the present study indicates that the age-dependent increase of HG strength as well as the between-gender differences are strongly related to changes of FFM values occurring during childhood. Moreover, the study provides a standard normative value of maximal HG strength for the healthy children population in Northern Italy.

Adolescent↗

PubMed2002

Effect of NO synthase inhibition on cardiovascular and pulmonary dysfunction in a porcine short-term model of endotoxic shock.

In a porcine model of endotoxic shock, we evaluated the circulatory and respiratory effects of NO synthase (NOS) blockade. Twenty anaesthetised pigs were divided into three groups and studied for 240 min after induction of endotoxic shock with lipopolysaccharides of Escherichia coli (LPS). After 180 min of endotoxic shock, one group (n = 6) received aminoguanidine, another group (n = 6) received N(G)-nitro-L -arginine methyl ester (L -NAME) and a third group (n = 8) received only LPS. A sham group (n = 3) was also studied. LPS decreased systemic arterial pressure and cardiac output (CO) and increased mean pulmonary arterial pressure (MPAP), pulmonary vascular resistance (PVR) and heart rate. Significant changes were also observed in compliance (-18.4%) and resistance (+33.6%) of the respiratory system. Aminoguanidine did not modify LPS-dependent effects, while, after L -NAME, a significant increase in MPAP, PVR and SVR and a decrease in CO were observed. In conclusion, aminoguanidine does not play a significant cardiocirculatory and pulmonary role in the short-term dysfunction of endotoxic shock, while L -NAME has a detrimental effect on haemodynamics, suggesting a protective role of constitutive NO production at vascular level during the early stages of endotoxaemia.

Animals↗

PubMed2001

Changes in motor control and muscle performance after a short-term body mass reduction program in obese subjects.

Two hundred and thirty obese subjects (age: 18-77 yr, BMI: 31.1-65.8 kg/m2) were studied before and after a 3-week body mass reduction (BMR) program, coupling restricted energy diet (1200-1500 kcal/day) with low intensity exercise prescription. It involved 5 days per week (consisting of one-hour dynamic aerobic standing and floor exercise plus 30 min of cycloergometer exercise at 60 W or, alternatively, 4 km outdoor leisure walking on flat terrain) and psychological counseling. One-leg standing balance test (OLSB) and stair climbing test (SCT) were employed to assess motor control and maximal lower limb muscle power, respectively. The BMR program induced a significant weight loss (4.1%; p<0.001), a higher reduction of body mass index (BMI) being observed in males than in females (p<0.001). OLSB performance time increased by 20.5% (p<0.001) after treatment, the improvement being evident in both genders. A 20.8% reduction in SCT time (p<0.05) was also observed and corresponded to a 13.2% increase (p<0.001) in average absolute muscle power and 15.0% increase (p<0.001) in specific muscle power (i.e. the power output per kg of body mass), with no differences between genders. In conclusion, in spite of the moderate reduction of body mass after restricted energy diet and low intensity physical conditioning, significant improvements in motor control and performance, likely to ameliorate the execution of simple daily activities, were observed in obese subjects.

Adolescent↗

PubMed2001

Short-term changes of cardiovascular risk factors after a non-pharmacological body weight reduction program.

OBJECTIVE: To test the short-term effectiveness of a 3 week hospital-based body weight reduction (BWR) program on selected coronary heart disease (CHD) risk factors in obese subjects. DESIGN: Intervention study to assess the modifications in CHD risk factor scores estimated according to Framingham risk factor categories (age, total cholesterol, high density lipoprotein (HDL) cholesterol, blood pressure, diabetes and smoking). SETTING: 3rd Division of Metabolic Diseases, Italian Institute for Auxology, Piancavallo (VB), Italy. SUBJECTS: Two-hundred and sixty-eight obese patients (43 men, 225 women, age range 19-81 y; body mass index (BMI) range 30-67). INTERVENTION: The BWR program consisted of a 3 week integrated energy-restricted diet (1200-1800 kcal/day), associated with moderate aerobic exercise, psychological counselling and educational lectures. RESULTS: Substantial reductions of total cholesterol (16.7%), HDL cholesterol (14.8%), systolic (11.2%) and diastolic blood pressure (8.7%) were observed at the end of the intervention, even with relatively moderate decrease in weight (4.1%) and in persistence of elevated BMI (over 40 kg/m2). The mean CHD Framingham score decreased by 16.1%, from 7.8 to 6.2. The BWR-induced changes were similar in both sexes, and across strata of age and BMI. CONCLUSIONS: The full-time participation of the patients in the hospital-based, integrated BWR program may explain the positive clinical outcome in all the subgroups considered, although the long-term results need to be quantified. SPONSORSHIPS: Partially supported by Progetti di Ricerca Corrente, Istituto Auxologico Italiano, IRCCS, Milan, Italy.

Adult↗

PubMed2001

Endothelin involvement in respiratory centre activity.

To evaluate the role of endothelin (ET) in respiratory homeostasis we studied the effects of the ET(A) and ET(B) receptor blocking agent bosentan on respiratory mechanics and control in seven anaesthetised spontaneously breathing pigs, for 180 min after single bolus administration (20 mg/kg i.v.). The results show that the block of ET receptors induced a significant increase in compliance and decrease in resistance of the respiratory system, entailing a significant reduction of diaphragmatic electromyographic activity, without affecting the centroid frequency of the power spectrum. Bosentan administration induced a significant increase in tidal volume (V(T)), accompanied by a significant decrease in respiratory frequency, without any significant change in pulmonary ventilation, CO(2) arterial blood gas pressure or pH. Since the relationship between V(T) and inspiratory time remained substantially constant after bosentan administration, the changes in respiratory pattern appear to be the result of an upward shift in inspiratory off-switch threshold. Both inspiratory and expiratory times during occluded breathing were increased by block of ET receptors, suggesting also a central respiratory neuromodulator effect of ET. In conclusion the present results suggest that the block of ET receptors in spontaneously breathing pigs exerts a role on mechanical properties of the respiratory system as well as on peripheral and central mechanisms of breathing control.

Airway Resistance↗

PubMed2001

Aerobic and anaerobic performance before and after a short-term body mass reduction program in obese subjects.

The cardiovascular response to an aerobic cycloergometer exercise test (ACET, 15 min at 60 W, 60 rpm) and the maximally attainable muscle power output, assessed by a stair climbing test (SCT), were evaluated in 60 obese patients (41 females and 19 males; age: 18-68 yr; body mass index, BMI: 40.8+/-4.8 kg/m2) before and after a 3-week body mass reduction (BMR) program, entailing integrated energy-restricted diet (1200-1500 kcal/day), low-grade aerobic exercise conditioning and individual and/or group psychological therapy. The daily conditioning protocol (5 days/week) consisted of: 1) 30 min of indoor jogging and dynamic aerobic standing and floor exercises performed with arms and legs, under the guidance of a therapist; 2) 30 min of cycloergometer exercise at 60 W; and/or 3) 4-km outdoor leisure walking on flat terrain. Three weeks of BMR program induced a significant weight loss (-4.5 %; p<0.001), a reduction of systolic (-11+/-14 mmHg, -7.3%,p<0.001) and diastolic (-7+/-9 mmHg, -7.3%,p<0.001) resting arterial blood pressure, as well as a reduction of heart rate at rest (-18.6%,p<0.001), during ACET (-11.3%,p<0.001) and 5 min thereafter (-14.8%,p<0.001). The subjective rating of perceived exertion in terms of breathlessness and general fatigue during ACET, scored on a 0-100 visual analogic scale, was significantly reduced (p<0.001) after BMR program. A 11.2% decrease in SCT time (p<0.001) was also observed, corresponding to a 9.6% increase (p<0.001) in average muscle power (W) and 14.6% increase (p<0.001) in specific muscle power (W.kg(-1)). In conclusion, a combination of energy restricted diet, low intensity aerobic exercise and psychological counselling appears to significantly improve both aerobic and anaerobic performance in morbidly obese subjects. Different factors (ie, reduction of body mass, shift in the balance between parasympathetic and sympathetic activity, a weight-loss dependent shift toward a more favourable region of the muscle power-velocity curve, acquisition of a certain degree of motor skillfulness during the conditioning program, improvement of self-esteem and motivation) might be responsible, alone or in combination, for these short-term positive effects of BMR program.

Adolescent↗

PubMed2000

Role of poly-(ADP-ribose) synthetase in lipopolysaccharide-induced vascular failure and acute lung injury in pigs.

PURPOSE: To assess the contribution of poly (adenosine 5'-diphosphate ribose) synthetase (PARS) to the development of bacterial lipopolysaccharide (LPS)-induced acute lung injury and vascular failure in pigs. MATERIALS AND METHODS: Four groups of anesthetized, paralyzed, and mechanically ventilated domestic white pigs. Group 1 served as control, whereas Escherichia coli LPS (20 microg/kg/h) was continuously infused in group 2. Group 3 received 20 mg/kg injection of 3-aminobenzamide (a selective inhibitor of PARS activity) 15 minutes before LPS infusion. Only 3-aminobenzamide and not LPS was injected in group 4. All animals were examined for 180 minutes. Systemic and pulmonary hemodynamics and lung mechanics were measured during the experimental period. Lung wet/dry ratio, bronchoalveolar lavage (BAL) protein levels and cell counts and lung nitrotyrosine (footprint of peroxynitrite) immunostaining were also measured in a few animals. RESULTS: LPS infusion evoked a progressive decline in systemic arterial pressure, a small increase in cardiac output, and biphasic elevation of pulmonary arterial pressure. Lung compliance declined progressively, whereas lung and total respiratory resistance rose significantly after LPS infusion. Prominent nitrotyrosine immunostaining was detected around small airways and pulmonary endothelium of LPS-infused animals. No significant changes in lung wet/dry ratio and BAL protein levels and cell counts were produced by LPS infusion. Pretreatment with 3-aminobenzamide did not alter the systemic and pulmonary hemodynamic responses to LPS infusion but eliminated the rise in pulmonary and total respiratory resistance. CONCLUSIONS: We concluded that PARS activation plays an important role in the changes of lung mechanics associated with LPS-induced acute lung injury but had no role in vascular failure.

Animals↗

PubMed1999

Laryngeal movements during the respiratory cycle measured with an endoscopic imaging technique in the conscious horse at rest.

A video-laryngoscopic method, implemented with an algorithm for the correction of the deformation inherent in the endoscope optical system, has been used to measure the dorsoventral diameter (Drg) and the cross-sectional area (CSArg) of the rima glottidis in five healthy workhorses during conscious breathing at rest. Simultaneous recording of the respiratory airflow was also obtained in two horses. Drg measured 82.7 +/- 4.5 mm (mean +/- S.D.) independently of the respiratory phase, and did not differ from the measurement in post-mortem anatomical specimens of the same horses. CSArg ranged from 1130 +/- 117 mm2 (mean +/- S.D.) during the inspiratory phase to 640 +/- 242 mm2 during the expiratory phase; being always narrower than tracheal cross-sectional area, which was 1616 +/- 224 mm2, as determined from anatomical specimens. Both inspiratory and expiratory airflow waves displayed a biphasic pattern. Maximal laryngeal opening occurred in phase with the second inspiratory peak, while during expiration CSArg attained a minimum value during the first expiratory peak which was significantly smaller (P < 0.01) than the area subsequently maintained during the rest of the expiratiory phase. These quantitative measurements of equine laryngeal movements substantiate the important role played by the larynx in regulating upper airway respiratory resistance and the expiratory airflow pattern at rest.

Algorithms↗

PubMed1996

The effects of locomotor-respiratory coupling on the pattern of breathing in horses.

1. To investigate the effect of locomotor activity on the pattern of breathing in quadrupeds, ventilatory response was studied in four healthy horses during horizontal and inclined (7%) treadmill exercise at different velocities (1.4-6.9 m s(-1)) and during chemical stimulation with a rebreathing method. Stride frequency (f(s)) and locomotor-respiratory coupling (LRC) were also simultaneously determined by means of video recordings synchronized with respiratory events. 2. Tidal volume (V(T)) was positively correlated with pulmonary ventilation (V(E)) but significantly different linear regression equations were found between the experimental conditions (P < 0.0001), since the chemical hyperventilation was mainly due to increases in V(T), whereas the major contribution to exercise hyperpnoea came from changes in respiratory frequency (f(R)). 3. The average f(R) at each exercise level was not significantly different from f(S), although there was not always a tight 1:1 LRC. At constant speeds, f(S) was independent of the treadmill slope and hence the greater V(E) during inclined exercise was due to increased V(T). 4. At any ventilatory level, the differences in breathing patterns between locomotion and rebreathing or locomotion at different slopes derived from different set points of the inspiratory off-switch mechanism. 5. The percentage of single breaths entrained with locomotor rhythm rose progressively and significantly with treadmill speed (P < 0.0001) up to a 1:1 LRC and was significantly affected by treadmill slope (P < 0.001). 6. A LRC of 1:1 was systematically observed at canter (10 out of 10 trials) and sometimes at trot (5 out of 14) and it entailed (i) a 4- to 5-fold reduction in both V(T) and f(R) variability, and (ii) a gait-specific phase locking of inspiratory onset during the locomotor cycle. 7. It is concluded that different patterns of breathing are employed during locomotion and rebreathing due to the interference between locomotor and respiratory functions, which may play a role in the optimization and control of exercise ventilation in horses.

Animals↗

PubMed1995

A new instrument for the measurement of rib cage and abdomen circumference variation in respiration at rest and during exercise.

A simple and inexpensive new extensometer for measuring changes in chest wall circumference during human respiratory movements is presented. The instrument detects the delay between ultrasound emission and reception at opposite ends of two rubber tubes encircling the rib cage and abdomen. Assuming a two degree of freedom model of the chest wall and employing an isovolume procedure for determination of volume-motion coefficients, extensometer estimation of tidal volume (VT) from changes of rib cage and abdomen circumference was compared with spirometer measurements at rest and during exercise on a cycle ergometer (55-155 W) in six subjects and, in four of them, on a treadmill (4-12 km.h-1). In three subjects hypercapnic hyperpnoea at rest was also studied. The slopes of the linear relationship between extensometer and spirometer VT (litres) averaged 0.9967 (SD 0.0117) (r2 = 0.995-0.998; n = 90-143) for cycle ergometer exercise, 1.0072 (SD 0.0078) (r2 = 0.991-0.998; n = 75-93) for treadmill exercise and 0.9942 (SD 0.0188) (r2 = 0.997-0.998; n = 18-25) for hypercapnic hyperpnoea. In all instances the slope of the regression line was consistent with the model of the identity line (slope = 1). The changes in end-expiratory lung volume between respiration at rest and during exercise were determined by the extensometers, and were nearly identical (98.4% on average) to those measured with the spirometer (r2 = 0.945; n = 24). It is concluded that determination of chest wall circumference with this new instrument is suitable for quantitative measurement of ventilation and lung volume variations in humans under most physiological conditions.

Adult↗

PubMed1989

Breath-by-breath estimate of alveolar gas transfer variability in man at rest and during exercise.

1. Breath-by-breath (BB) oxygen and carbon dioxide transfer (VO2 and VCO2) at the mouth, together with respiratory pattern, were determined over sequences of 100 consecutive breaths in six subjects at rest and during cycloergometric exercise (75 W). 2. BBVO2 and VCO2 at alveolar level were calculated taking the changes of pulmonary gas stores throughout each single ith breath into account. This requires knowledge of the alveolar volume at the beginning of the breath (VA.i-1), which cannot be directly measured on a BB basis at present. Therefore a constant nominal value, ranging from 0 to 5 l, was attributed to VA,i-1. 3. It was found that: (i) all nominal VA.i-1 values employed for the estimate of steady-state alveolar gas exchange yield the same average value but greatly reduce BB variability with respect to gas exchange as determined at the mouth; (ii) no unequivocal criterion was identified to select the appropriate VA.i-1 value; and (iii) the apparent kinetics of alveolar VO2 after work onset may be influenced by the VA.i-1 value selected for the calculation, and by the change in lung volume at the onset of exercise. 4. It was concluded that: (i) as long as VA.i-1 cannot be measured for each single breath, 'true' alveolar gas exchange remains elusive; hence, (ii) it is not possible to establish the extent to which the alveolar gas exchange variability depends on physiological phenomena using available methods.

Adult↗

PubMed1987

Respiratory airflow pattern in patients with chronic airway obstruction.

Previous experimental evidence has shown that in healthy humans inspiratory airflow waveform can be optimized according to minimum rate of work criteria when the respiratory energetic requirements become a substantial fraction of the general metabolism (i.e., during exercise hyperpnea and maximum voluntary ventilation). In patients with chronic airway obstruction (CAO) the relative energetic expenditure devoted to respiration is also greatly enhanced at rest. To investigate the performance of a system also controlling airflow wave pattern in this condition we evaluated by Fourier analysis the harmonic content of respiratory flow waves recorded at rest and during exercise hyperpnea (25 and 50 W on cycloergometer) in 15 patients. The results were compared with those we previously obtained in normal subjects and with some theoretical models. It was found that, while normal subjects display at rest an inspiratory flow waveform reasonably close to a sinusoidal model and adopt a more rectangular and economical flow shape during exercise hyperpnea, patients with CAO show a rather rectangular inspiratory flow shape also at rest, without any remarkable change at higher levels of ventilation. So, in general terms, the airflow pattern employed by patients at rest entails a reduction in the rate of dynamic inspiratory work of about 12% over that required by a sinusoidal waveform, and no further advantage is observed during exercise hyperpnea. Some features of the expiratory flow wave were also analysed. As no model of the respiratory system mechanics presently developed can explain the findings obtained in CAO patients purely on the basis of their altered mechanical parameters, it has been suggested that more complex control of respiratory airflow is operating in this class of patient.

Female↗

PubMed1986

Beclomethasone dipropionate does not affect mucociliary clearance in patients with chronic obstructive lung disease.

Aerosolized steroids may be implicated in the increased incidence of chest infections. To evaluate such a possibility, we utilized a double-blind study to investigate the acute effect of inhaled beclomethasone dipropionate on mucociliary clearance in 10 patients with chronic obstructive lung disease (5 receiving the drug and 5 placebo). Mucociliary clearance was measured by inhalation of a 99mTc-labelled albumin aerosol. The resulting radioactivity was recorded externally by a large-field gamma camera and dedicated computer for 3 consecutive hours without patient repositioning. After 1-hour baseline recording, the subjects inhaled from a commercial pressurized canister either beclomethasone dipropionate (250 micrograms) or vehicle alone. The recording was then continued for 2 more hours. No statistically significant difference was found in clearance rates throughout the entire period of observation between patients receiving beclomethasone and controls. The data suggest that mechanisms other than mucociliary function impairment are responsible for the increased incidence of chest infections which may accompany steroid treatment by the inhalatory route.

Adult↗

PubMed1984

Inspiratory flow pattern in humans.

The theoretical estimation of the mechanical work of breathing during inspiration at rest is based on the common assumption that the inspiratory airflow wave is a sine function of time. Different analytical studies have pointed out that from an energetic point of view a rectangular wave is more economical than a sine wave. Visual inspection of inspiratory flow waves recorded during exercise in humans and various animals suggests that a trend toward a rectangular flow wave may be a possible systematic response of the respiratory system. To test this hypothesis, the harmonic content of inspiratory flow waves that were recorded in six healthy subjects at rest, during exercise hyperventilation, and during a maximum voluntary ventilation (MVV) maneuver were evaluated by a Fourier analysis, and the results were compared with those obtained on sinusoidal and rectangular models. The dynamic work inherent in the experimental waves and in the sine-wave model was practically the same at rest; during exercise hyperventilation and MVV, the experimental wave was approximately 16-20% more economical than the sinusoidal one. It was concluded that even though at rest the sinusoidal model is a reasonably good approximation of inspiratory flow, during exercise and MVV, a physiological controller is probably operating in humans that can select a more economical inspiratory pattern. Other peculiarities of airflow wave during hyperventilation and some optimization criteria are also discussed.

Adult↗

PubMed1984

Acute effect of inhaled salbutamol on mucociliary clearance in health and chronic bronchitis.

We investigated in a double-blind study the acute effect of the inhaled beta 2-adrenergic agent salbutamol on mucociliary clearance in man. Subjects were 20 patients with chronic bronchitis (10 receiving the drug and 10 placebo) and 6 healthy individuals (3 receiving the drug and 3 placebo). Mucociliary clearance was evaluated after inhalation of a pressurized 99mTc-labelled a albumin aerosol (median mass aerodynamic diameter 2.85 microns). Particle deposition and clearance was determined by external recording with a large-field gamma camera and dedicated computer, for three consecutive hours without moving the subject. After 1 h baseline clearance recording the subject was given either salbutamol (500 micrograms) or vehicle alone from a commercial pressurized nebulizer; recording was then continued for a further 2 h (test period). Both patients and normals treated with salbutamol showed a significant increase in the rate of clearance when compared with their respective control group receiving placebo. Clearance rates (percentage activity cleared per hour) from the lungs in the hour after salbutamol inhalation averaged 33.1% +/- 13.5 (SD) per hour, for patients (control 12.2% +/- 5.6 (SD) per hour, p less than 0.001) and 16.1% +/- 4.3 (SD) per hour for normals (control 7.8% +/- 2.0 (SD) per hour, (p less than 0.005). Significant differences were also found in clearance rate before and after salbutamol inhalation in both treated groups. Cough events did not produce any significant effect on average mucociliary clearance. However, visualization of serial computer images in individual patients showed that cough may generate appreciable upward, downward or even lung-to-lung movements of radioactive boli.

Adult↗