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PubMedDate not supplied

Mechanical properties of the lungs of posttraumatic rats are improved by including fat in total parenteral nutrition.

Posttraumatic lung failure is often associated with alterations in lung surfactant composition and function. Our previous studies with total parenteral nutrition (TPN) have shown the effect of fat supply on phospholipid composition in pulmonary surfactant. Consequently, we attempted to determine whether fat supply would also improve the functional properties of the lung and surfactant. After polytrauma consisting of laparotomy, hypovolemia, and a single femur fracture, the animals were fed only parenterally for 14 days. Two groups of rats were infused via the jugular vein with isocaloric (260 kcal/kg/day) and isonitrogenous (5.62 gN/kg/day) regimens. The nonprotein calories were given either as glucose alone or 30% of calories as fat. Lung function was assessed by measurement of static lung compliance and total lung capacity. Surfactant isolated from lavage fluid was evaluated by means of a Wilhelmy balance. In agreement with our previous studies, in which we obtained a higher level of saturated lecithin in the fat groups, we found significantly (p less than 0.05) increased compliance (2.93 +/- 0.54 ml/cm H2O/kg BW) in the fat group compared to the carbohydrate group (2.02 +/- 0.36 ml/cm H2O/kg BW). Furthermore, a significantly (p less than 0.05) elevated total lung capacity was noted in the fat group (32.60 +/- 3.90 vs 26.00 +/- 1.45 ml/kg BW). The relatively improved surface tension properties as expressed by stability index (S = 0.89 +/- 0.24 vs 0.66 +/- 0.22) and minimum surface tension (gamma min = 18.5 +/- 5.01 vs 20.75 +/- 2.81) is a characteristic change, and was seen in the fat group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

The effect of smoking cessation and modification on lung function.

The purpose of this study was to obtain more information about the effect on lung function of stopping smoking or of modifying the smoking habit and to determine the time course of change. We followed a group of 75 cigarette smokers who attended a smoking cessation clinic in May 1973, using a respiratory symptom questionnaire, spirometry, closing volumes, and the slope of the alveolar plateau of the single-breath nitrogen test. Subjects were tested before stopping smoking and at 1, 3, 6, and 12 months after the initial testing. We found a significant (P less than 0.05) improvement in closing volume as a percentage of vital capacity and closing capacity as a percentage of total lung capacity at 6 and 12 months and in the slope of the alveolar plateau at 1, 6, and 12 months in those who stopped smoking. There was also a dramatic decrease in respiratory symptoms in those who stopped smoking, a moderate decrease in those who reduced their consumption by at least 25 per cent, and very little change in those who did not appreciably modify their smoking consumption.

Adult↗
PubMed2004

Diagnosis of interstitial lung disease in children.

Chronic interstitial lung disease (ILD) in infants and children is a challenging diagnostic clinical problem. There are many unresolved and controversial issues in the diagnosis of this heterogeneous group of uncommon disorders in children. Diagnosis requires a high index of suspicion as the initial clinical manifestations are subtle, highly variable and non-specific. There is no consensus for the clinical diagnostic criteria of paediatric ILD. The spectrum of clinical findings is highly variable. The diagnostic evaluation of a child with suspected ILD includes a comprehensive history, physical examination, oxygen saturation (at rest, during exercise or during feeding), a plain chest x ray and a high-resolution thin-cut tomography scan of the chest. Pulmonary function studies can be useful in older children; these typically show a restrictive pattern with a decreased forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and total lung capacity, but normal FEV(1)/FVC. A systematic approach to diagnosis is useful in the evaluation of an infant or child with suspected chronic ILD. Due to the rarity of most of these disorders, multi-centre collaboration is needed to improve our understanding of this orphan lung disease.

Biopsy, Needle↗
PubMed1996

Strain-induced growth of the immature lung.

To investigate the relationship between strain and postnatal lung growth, two groups of weanling ferrets were tracheotomized: the study group was exposed for 2 wk to a continuous positive airway pressure (CPAP) of 6 cmH2O and the other group was exposed to atmospheric pressure (control). Total lung capacity after 2 wk was approximately 40% higher in the CPAP-exposed animals than in the control animals (n = 19 for the control group and 18 for the study group; P < 0.01). CPAP exposure was also associated with increases in lung weight and total lung protein and DNA contents. Lung recoil, measured in a subgroup of animals, was characterized by air-filled and saline-filled static expiratory pressure-volume curves. Neither in the air-filled lungs nor saline-filled lungs was there a significant difference between CPAP-exposed and control animals in lung recoil at equal fractions of total lung capacity. These data indicate that mechanical strain was associated with an acceleration of lung growth in immature ferrets. The preservation of volume-corrected lung recoil and the expected contribution of surface forces and tissue forces to lung recoil in CPAP-exposed animals suggest that this response did not involve simple lung distension but included a remodeling of the lung parenchyma.

Animals↗
PubMed1981

Pathologic and physiologic effects of aspiration of hydrocarbons in the rat.

In a series of laboratory rats, pathologic and physiologic changes of the lungs were studied for 2 wk after intratracheal instillation of kerosene. The ratio of lung weight to body weight increased, indicating pulmonary congestion. Pathologically, 2 types of changes were seen: a generalized hyperemia and a focal bronchopneumonia. Physiologically there was an upward shift to the left of the static pressure-volume curve, with increases in total lung capacity of 35 to 40%. This was true whether air or saline was used as the inflating medium. All the changes described were maximal by 24 h after kerosene instillation and tended to return to baseline within 2 wk. Although static compliance of the lung increased, when normalized for total lung capacity there was no change, indicating that the shift was functionally equivalent to opening new lung units. We speculate that the leftward shift in the pressure-volume curve was due either to a reversible effect on lung elastin, or to changes in contractile elements located in lung parenchyma.

Animals↗
PubMed1990

Multi-breath and single breath helium dilution lung volumes as a test of airway obstruction.

Total lung capacity (TLC) and residual volume (RV) measurements derived from multi-breath and single breath helium dilution methods were combined to produce four indices of gas mixing: single breath volume/multi-breath volume ratio (TLCr, RVr) or multi-breath volume minus single breath volume difference (TLCd, RVd). The reproducibility of these indices and their sensitivity and specificity in discriminating between normal subjects and those with mild asthma and severe chronic obstructive pulmonary disease (COPD) was assessed. The total lung capacity ratio (TLCr) was the superior variable overall, providing a single range for both sexes with a specificity and sensitivity similar to that of the forced expiratory volume in one second (FEV1) in the diagnosis of airflow obstruction. Despite the similar sensitivity, correlation between TLCr and FEV1 was only moderate (r = 0.56). This may reflect greater influence of peripheral rather than central airflow obstruction on TLCr. Combining both tests improved sensitivity in the detection of airways obstruction in the asthmatic and COPD groups studied.

Adult↗
PubMed1987

Pulmonary restrictive effect of bracing in mild idiopathic scoliosis.

The use of bracing in the treatment of mild idiopathic scoliosis is controversial. A study of 33 adolescents showed that bracing significantly decreased lung volumes. Functional residual capacity was reduced by a mean of 26%, 18% of children showing a reduction of greater than 40%. The mean reduction in total lung capacity was 16% and in forced vital capacity 18%. This restriction of lung function by bracing might have a deleterious effect on lung growth or might impose an additional risk factor in the presence of other disorders, such as asthma and diaphragmatic weakness. The use of bracing in individuals with mild scoliosis should be judiciously reassessed.

Adolescent↗
PubMed2004

Systemic and pulmonary effects of fluticasone administered through a metered-dose inhaler in rats.

BACKGROUND: Metered-dose inhalers (MDIs) are convenient, simple, inexpensive, and reproducible devices for administering aerosolized drugs through the pulmonary route, but methods have not been available for use of these devices in small animals. OBJECTIVE: We sought to test the efficacy of delivery of fluticasone through an MDI to rats with a rodent-adapted spacer chamber and to compare this treatment with systemic dexamethasone for the acute pulmonary allergic inflammatory response. METHODS: Changes in body and thymus weights were used as indicators for systemic steroid effects. Rats were sensitized to ragweed pollen extract 2 weeks before the experiment, and pulmonary allergic responses were evaluated 48 hours after a single aerosolized antigen challenge on the basis of bronchoalveolar leukocytes, lung tissue sections, total lung capacity, and forced expiratory volumes. RESULTS: Inhaled fluticasone caused dose-related systemic effects, indicating successful pulmonary drug delivery. Inhaled fluticasone was more effective than placebo but less effective than systemic dexamethasone in attenuating the increase in lung eosinophils and inflammatory infiltrates and the decrease in total lung capacity associated with the allergic inflammatory response. Inhaled fluticasone prevented airway obstruction and proximal inflammation, as did dexamethasone, but it appeared to have less effect in areas of lung served by the most distal airways. CONCLUSION: This is an effective method for use of MDIs to deliver inhaled drugs to small laboratory animals, and it should be valuable for investigations of treatment effects, as well as for in vivo testing of delivery devices.

Androstadienes↗
PubMed1998

Thoracoscopic T2-T3 sympathicolysis for essential hyperhidrosis in childhood: effects on pulmonary function.

Thoracoscopic T2-T3 sympathicolysis (TS) is a minimally invasive treatment for patients suffering from severe, refractory essential hyperhidrosis (EH). TS has previously been shown to be safe and efficacious in children. In order to examine the effects of TS on respiratory function, pulmonary function tests (PFT) were performed prior to and 6 weeks and 6 months after TS in 12 children with EH (3 boys; mean age 12.8+/-2.5 years). Small asymptomatic decreases in forced expiratory volume in one second (FEV1; -2%), forced expiratory flow after expiration of 75% of vital capacity (FEF75; -9.6%), total lung capacity (TLC; -1%), transfer factor for diffusion of carbon monoxide (T(LCO); -7.6%), and transfer coefficient for diffusion of carbon monoxide (K(CO); -1.5%) were observed 6 weeks after TS. These changes are comparable to those observed in adults but did not reach statistical significance in small children. In line with observations in adults, TLC (and T(L,CO)) returned to baseline values 6 months after TS, whereas FEV1, FEF75, and K(CO) remained at their 6-week level. In conclusion, TS causes only small, statistically insignificant, and asymptomatic decreases in pulmonary function in children. TS can, therefore, be considered a safe treatment option in children suffering from severe, refractory EH.

Adult↗
PubMed1985

Effects of formaldehyde and acetaldehyde inhalation on rat pulmonary mechanics.

Two groups of 12 male Wistar rats received either 243 ppm of acetaldehyde or 5.7 ppm of formaldehyde for 8 h a day, 5 days a week during 5 weeks. These levels represent three times the threshold limit values (TLV) for these substances in Brazilian legislation. The animals were evaluated by pulmonary function tests before and after exposure to the pollutants. The data obtained from these rats were compared with those of 12 controls, housed in identical conditions for the same length of time but breathing normal air. The results showed an increase of the functional residual capacity, residual volume, total lung capacity and respiratory frequency in the rats exposed to acetaldehyde atmosphere. The animals exposed to formaldehyde did not present pulmonary function alterations when compared with the controls. The damage caused by acetaldehyde to the peripheral regions of the lung parenchyma, affecting small airways or altering pulmonary elastic properties, is discussed. It is suggested that the Brazilian TLV for acetaldehyde (78 ppm) is not as safe as that for formaldehyde (1.6 ppm).

Acetaldehyde↗
PubMed1986

Pulmonary function abnormalities in long-term survivors of childhood cancer.

Pulmonary function testing (PFT) was performed on 29 long-term survivors of childhood cancer. The patients, whose mean age was 11.7 years and whose mean age at diagnosis was 3.7 years, included 12 females and 17 males. Original diagnoses included 15 patients with leukemia and 14 individuals with solid tumors. Nine patients had received cyclophosphamide and 20 had received radiation therapy. Included in this latter group were five patients who had received radiation therapy to the thorax. Eight patients had acquired pneumonia during their treatment. Physical examination was normal in all the patients, and none had a history of acute or chronic pulmonary disease. PFT demonstrated an incidence of abnormalities in forced vital capacity (FVC) and/or total lung capacity (TLC) in 48% of the patients. Patients who were under 3 years of age at the time of diagnosis or who had received radiation to the thorax were more likely to demonstrate PFT abnormalities, but these differences did not reach statistical significance. The natural history of pulmonary function and subsequent respiratory disease in survivors of childhood cancer requires further definition.

Adolescent↗
PubMed1998

Respiratory ultrasonography of human parasternal intercostal muscle in vivo.

The parasternal intercostal muscle (PS) is phasically active during inspiration, but its mechanical function in humans is poorly understood. The aim of this study was to describe PS motion ultrasonographically during respiration. We used a 7.5-MHz curvilinear phased array transducer to obtain ultrasonograms of the second right and left interspace in the sagittal plane, 2-3 cm lateral to the sternum, in 4 seated subjects (3M, 1F), during tidal breathing and at residual volume (RV), functional residual capacity (FRC) and total lung capacity (TLC). Images were recorded on videotape and off-line, digitized, transferred to a workstation, and traced manually to outline the external and pleural borders of the PS muscle in relation to a rectangle bounded by the second and third ribs. To assess PS shape and motion, we measured inter-rib distance (Lics), PS thickness (Tps), and motion of the midpoint of the muscle relative to the midpoint of the reference rectangle (Mps). We also calculated the average radius of curvature of the external and pleural PS borders (Re, Rp) over the mid 50% of Lics, and 1/Re and 1/Rp. During tidal breathing, Mps moved ventrally by 0.42 +/- 0.06 mm (p = 0.001) against the pleural pressure gradient, and 1/Re and 1/Rp decreased by 1.1 x 10(-2) +/- 1.6 x 10(-3) mm-1 and 8.4 x 10(-3) +/- 1.4 x 10(-3) mm-1, respectively (p < 0.001). Lics and Tps did not change (p > 0.19). We conclude that, during inspiration, the PS moves ventrally and straightens, and lung volume, neural activation and pleural pressure influence PS shape and motion. The findings support an intercostal stabilizing function of the PS and suggest a novel mechanism by which the PS may contribute to the inspiratory fall in pleural pressure.

Adult↗
PubMed2002

Respiratory muscle evaluation of the patient with neuromuscular disease.

This review presents clinically relevant issues regarding the assessment of respiratory muscles in individuals with neuromuscular disorders, and discusses the advantages and disadvantages of methods generally available to the clinician. Vital capacity (VC) and total lung capacity (TLC) are routinely measured in pulmonary function laboratories and are typically reduced in the context of severe respiratory muscle weakness, but the sensitivity and specificity of these measures are limited. Better measures of respiratory muscle weakness are maximal static inspiratory and expiratory pressures (PI max and PE max). PI max is reduced even with mild or moderate degrees of inspiratory muscle weakness, but low values also may be related to submaximal effort. To circumvent this problem, pressures can be measured using simpler maneuvers such as a maximal sniff. Specific tests of diaphragm function such as measurements of maximal transdiaphragmatic pressure are invasive and not routinely available to the clinician. Recently, noninvasive methods that specifically assess diaphragm function, such as diaphragm ultrasound of the zone of apposition and magnetic or electrophrenic nerve stimulation, have shown promise as new techniques for clinical use.

Journal Article↗
PubMedDate not supplied

Airway effects of low concentrations of sulfur dioxide: dose-response characteristics.

The acute respiratory effects of exposure to low-level, short-term sulfur dioxide (SO2) were studied in ten asthmatic and ten healthy subjects. Subjects were exposed in an environmental chamber in a double-blind, random sequence to SO2) levels of 0.00, 0.25, 0.50, 0.75, and 1.00 ppm for 40 min. During the first 10 min subjects exercised on a cycloergometer at a level of 450 kpm/min. On separate days, subjects were exposed to 0 and 1.0 ppm SO2 in the absence of exercise. In exercising asthmatic subjects, breathing 1 ppm SO2 resulted in significant changes from baseline in airway resistance (Raw), forced expiratory volume in 1 sec (FEV1.0), maximal expiratory flow at 60% of the vital capacity (VC) below total lung capacity on the partial flow volume curve [MEF40% (P)] as well as reductions in flows at 50% of VC (Vmax50%). None of these parameters showed significant changes for exposures to 0.5 ppm or less, with the exception of small decreases (i.e., less than 0.2 L/sec) in Vmax50% at 0.25 and 0.5 ppm. Ten minutes after the end of exercise, there were no statistically significant differences from baseline, even though SO2 was still present in the chamber atmosphere. For asthmatic subjects, the average changes in Raw, FEV1.0, MEF40%(P), and Vmax50% increased as SO2 levels increased, suggestive of a dose-response relationship with a consistent effect first seen at 0.75 ppm. In individual exercising asthmatics, responses may occur at levels of SO2 below 0.75 ppm. No changes were seen in healthy individuals on any day, or in asthmatic subjects at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1975

Cardiorespiratory effects of rapid saline infusion in normal man.

We have studied the cardiorespiratory effects of the rapid infusion (100 ml/min) of 2 liters of saline in four normal seated subjects. Cardiac output and pulmonary arterial pressure increased, while vital capacity (VC) and total lung capacity (TLC) decreased. There was an increase in closing volume (CV) without any detectable change in lung compliance or flow-volume characteristics. There was an increase in Pao2 during infusion period which can be related to better matching of ventilation to perfusion and to improved hemoglobin transport. In the recovery stage as cardiac output, pulmonary arterial pressure, TLC, and VC all returned toward control values CV remained high. In two subjects CV occurred within the normal tidal range of ventilation and in these two subjects Pao2 fell significantly below values obtained in the control period. The results suggest that rapid saline infusion in man can cause interstitial edema and lead to premature airway closure and hypoxemia.

Airway Resistance↗
PubMed1987

Effect of substance P on cardiovascular and respiratory function in subjects.

The effect of substance P (SP), administered both intravenously and by inhalation, has been studied in normal and asthmatic humans. Intravenous infusion of SP (0.2-3.3 pmol X kg-1 X min-1) achieving a plasma concentration of SP between 5 and 25 pM produced vasodilatation (mean +/- SD), maximal increase in skin temperature (0.9 +/- 0.3 degree C) (P less than 0.05), and fall in diastolic blood pressure (8.5 +/- 2.9 mmHg) (P less than 0.05) associated with an increase in heart rate (15 +/- 10 beats/min) (P less than 0.05). All subjects had a fall in Vp30 (airflow at 70% of forced vital capacity measured from total lung capacity after a forced partial expiratory flow maneuver) at low infusion rate (P less than 0.05) and a significant rise at the highest infusion rate (P less than 0.05). Ventilation at rest and when stimulated by transient hypoxia increased (mean increase in resting ventilation 0.73 +/- 0.4 l/min and mean percent increase in transient ventilatory hypoxic response 41 +/- 27%). There was a small nonsignificant increase in plasma norepinephrine but no change in epinephrine or histamine. Inhaled SP, up to 0.7 mumol, caused a small nonsignificant fall in airway function in asthmatic subjects. SP has demonstrable effects on vascular smooth muscle and control of ventilation but at the doses studied had little effect on airway function.

Adult↗
PubMed1997

Diaphragm interference pattern EMG and compound muscle action potentials: effects of chest wall configuration.

The effect of chest wall configuration on the diaphragm electromyogram (EMGdi) was evaluated in five healthy subjects with an esophageal electrode for both interference pattern EMGdi (voluntary contractions) and electrically evoked diaphragm compound muscle action potentials (CMAPs). Diaphragm CMAPs (both unilateral and bilateral) were evaluated for the baseline-to-peak amplitude (Ampl), the time from the onset of the CMAP to first peak (T1), root mean square (RMS), and center frequency (CF) values of the CMAP power spectrum. CF values from the interference pattern EMGdi power spectrum were also calculated. For CMAPs obtained at an electrode position least influenced by variations induced by electrode positioning, Ampl increased with diaphragm shortening from functional residual capacity (FRC) to total lung capacity (TLC) by 101 and 98% (unilateral and bilateral, respectively). Bilateral CMAP RMS values increased 116% from FRC to TLC. CMAP T1 values decreased with diaphragm shortening from FRC to TLC by 1.1 and 2.1 ms for the unilateral and bilateral stimulations, respectively, and CF increased for the bilateral diaphragm CMAPs with diaphragm shortening. CF values from the interference pattern EMGdi did not show any consistent change with chest wall configuration. Thus CF values of the interference pattern EMGdi obtained with an esophageal electrode can be considered reliable for physiological interpretation, at any diaphragm length (if electrode positioning and signal contamination are controlled for), contrary to the diaphragm CMAPs, which are sensitive to changes in chest wall configuration. It is speculated that the different results (over the effects of chest wall configuration on interference pattern EMGdi and diaphragm CMAPs) amy be because of summation properties of the signals and how these influence the EMG power spectrum.

Action Potentials↗
PubMed1981

Pulmonary function and exercise gas exchange in survivors of adult respiratory distress syndrome.

Pulmonary function studies were performed on 13 survivors of adult respiratory distress syndrome (ARDS). Six of these 13 patients had a forced vital capacity (FVC) and total lung capacity (TLC) less than 80% of predicted within 2 months of the onset of ARDS. Seven patients followed 6 months or more showed no significant difference between measured and predicted FVC (p = 0.26) or TLC (p = 0.12). The diffusing capacity of carbon monoxide was significantly lower than predicted normal values (p less than 0.001). Although the alveolar arterial oxygen tension gradient (delta AaPO2) was within the predicted normal range for 11 nonsmokers at rest, for 7 patients who exercised (1.0 less than VO2 less than 1.5 L/min), delta AaPO2 increased. The ratio of dead space to tidal volume decreased to less than 0.25 when VCO2 exceeded 1.0 L/min. We concluded that lung mechanics return to predicted normal values within 4 to 6 months after ARDS, but abnormalities of pulmonary gas exchange persist. Pulmonary vascular obstruction does not appear to explain persistent abnormalities of gas exchange.

Adolescent↗