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Results for “Functional Residual Capacity”

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PubMed1991

Analysis of expiratory pattern for monitoring bronchial obstruction in school-age children.

This study was designed to assess the validity of the percent of volume expired at tidal peak flow (dV/Vt) as an indicator of bronchial obstruction in school-age children. We analyzed 126 dV/Vt ratios and compared them with spirometric and plethysmographic results measured in 24 healthy (14 males) and 60 asthmatic (41 males) children; 42 of them underwent measurements before and after bronchial challenge with histamine. The two groups differed in resistance, forced expiratory volume in 1 sec (FEV1), and forced expiratory flows, as percents of predicted (FEV1: 94.6 +/- 2.4% in controls vs 86.7 +/- 1.6% in asthmatics; P less than 0.001). They did not differ in peak expiratory flow (PEF), forced vital capacity, functional residual capacity, measured by body plethysmography, and in dV/Vt. The dV/Vt was found to correlate with FEV1 (r = 0.58, P less than 0.001), PEF (r = 0.57, P less than 0.001), and other lung function parameters. Forty-two of the asthmatic children performed a bronchoprovocation histamine test. The fall of dV/Vt after histamine was significantly correlated (r = 0.61, P less than 0.001) with the variation in FEV1 and other lung function parameters. We conclude that dV/Vt is a good indicator of bronchial obstruction, as useful in school-age children as in adults and infants, with no need for the subject's cooperation.

Adolescent↗

PubMed2001

Compromised respiratory function in postnatal lambs after placental insufficiency and intrauterine growth restriction.

Epidemiologic studies have shown persistent effects of low birth weight on respiratory function and lung health, but underlying mechanisms are not understood. Our aim was to determine the effects of intrauterine growth restriction (IUGR), a major cause of low birth weight, on postnatal respiratory function. IUGR was induced by umbilico-placental embolization during late gestation in chronically catheterized sheep. Umbilico-placental embolization was performed between 120 d of gestation and term ( approximately 146 d) during which fetuses were hypoxemic and hypoglycemic relative to controls. Umbilico-placental embolization led to a 48% reduction in birth weight compared with controls, and throughout the postnatal study period IUGR lambs (n = 8) remained lighter than controls (n = 8). Respiratory function was repeatedly studied in lambs for 8 wk after birth; during this period, IUGR lambs were mildly hypoxemic and tended to be hypercapnic compared with controls. In IUGR lambs, relative to controls, O(2) consumption (mL/min/kg) and minute ventilation (mL/kg) were increased and pulmonary diffusing capacity (adjusted for functional residual capacity) was decreased. Functional residual capacity, measured by helium dilution, and total lung capacity (measured at 30 cm H(2)O) were smaller in IUGR lambs than in controls. When adjusted for functional residual capacity, static lung compliance was reduced and chest wall compliance was increased in IUGR lambs. At 8 wk, pulmonary DNA and protein concentrations were decreased in IUGR lambs relative to controls. We conclude that restriction of fetal growth by placental insufficiency induces alterations in the lungs and chest wall that result in persistent impairments in respiratory function during early postnatal life.

Animals↗

PubMed2002

Respiratory function in singleton and twin pregnancy.

OBJECTIVE: Singleton pregnancy causes important changes in respiratory function. The incidence of twin pregnancies is increasing, but it is not known whether affected women suffer greater respiratory compromise. The aim of this study was to determine if changes in respiratory function during pregnancy in healthy women were greater in those with a twin pregnancy compared with those with a singleton pregnancy. DESIGN: Cross sectional study. SETTING: London teaching hospital. POPULATION: Healthy pregnant women attending the antenatal clinic and ultrasound department. METHODS: A cross sectional study of respiratory function was performed in 68 women with twin pregnancies (17 examined in the first trimester, 35 second trimester, 16 third trimester) and 140 women with singleton pregnancies (28, 80, 40, respectively) and 22 non-pregnant women. Women were examined once between 7 and 40 weeks of gestation. Forced vital capacity, relaxed vital capacity, forced expiratory volume in 1 second (FEV1), peak flow, inspiratory capacity, functional residual capacity (FRC), expiratory reserve volume, pulmonary diffusing capacity and minute ventilation were measured. RESULTS: Both in twin and singleton pregnancies, the mean FRC and expiratory reserve ventilation of women studied in the third trimester and minute ventilation of women studied in each trimester differed significantly from that of the non-pregnant women. There were, however, no significant differences demonstrated in respiratory function between healthy women with twin as compared with singleton pregnancies. CONCLUSION: In healthy women, the extra demands of atwin compared with a singleton pregnancy do not compromise further the respiratory system.

Adult↗

PubMed1984

Vascular rings and slings: long-term follow-up of pulmonary function.

Between 1968 and 1983, 54 patients underwent surgery for symptomatic aortic arch and pulmonary artery anomalies at St Christopher's Hospital for Children. Presenting symptoms included stridor, wheeze, apnea, recurrent pulmonary infections, or dysphagia. Diagnosis was established with chest roentgenogram, bronchoscopy, barium esophagram, and arteriography. Four types of vascular anomalies were encountered; double aortic arch (24 patients), right aortic arch with left ligamentum arteriosum (17 patients), anomalous innominate artery (10 patients), and pulmonary artery sling (three patients). There were no intraoperative deaths and only one postoperative death. All surviving patients had immediate relief of their severe respiratory or swallowing symptoms. Mild respiratory symptoms persisted postoperatively from 3 months to 4 years and included frequent or severe upper respiratory infections, persistent cough, stridor and pneumonia. Five of the 53 surviving patients were lost to follow up. The remaining 48 patients were followed from 6 months to 14 years and all but one patient noted complete resolution of all respiratory symptoms. Twenty-nine patients at follow up were old enough to undergo pulmonary function testing including vital capacity, functional residual capacity, and inspiratory and expiratory flow volume loops. Seventeen of these 29 asymptomatic patients consented to these studies, and nine of these patients had abnormal flow volume loops indicative of significant central airway obstruction; the other eight studies were normal. We conclude that surgical repair for vascular rings and slings is safe and symptomatically efficacious. However, anatomic tracheal or bronchial distortion persists in a significant number of these patients as evaluated by pulmonary function studies.

Adolescent↗

PubMed1992

Structural change of the thorax in chronic obstructive pulmonary disease.

This study examines structural changes of the thorax in hyperinflated subjects with chronic obstructive pulmonary disease (COPD). Age-matched normal subjects were used for comparison. Thoracic dimensions were determined using anteroposterior and lateral chest radiographs performed at total lung capacity, functional residual capacity, and residual volume. Rib cage dimensions (lateral diameter, rib angle, anteroposterior diameter) and diaphragm position were determined at each lung volume. There were no significant differences in rib cage dimension between the COPD and normal subjects for all lung volumes. In contrast, the diaphragm was significantly lower in the COPD subjects. The change of rib cage dimensions in the COPD subjects (for a similar volume change) was not different from that in normal subjects, whereas the change of diaphragm position in the COPD subjects (for a similar volume change) was reduced. In conclusion, the primary structural change of the thorax in COPD with chronic hyperinflation is confined to the diaphragm, with no appreciable structural change in the rib cage.

Aged↗

PubMed1983

Respiratory function after paralysis of the right hemidiaphragm.

We studied a 45-yr-old man with normal lung function before and 7 wk after right phrenic nerve crush. Total lung capacity, functional residual capacity, and forced vital capacity decreased with residual volume remaining unchanged. Static compliance was also unchanged. Ventilatory response to CO2 (delta Ve/delta PaCO2) was preserved, but P0.1 response to CO2 (delta P0.1/delta PaCO2) increased. Analysis of raw mouth pressure suggested that these responses were the result of a new rapid pattern of inspiratory pressure development. Regional washout was slowed on the side with paralysis, but the normal apex-to-base gradient of regional volumes was preserved. Inhaled 133Xe boluses were distributed away from the side of paralysis, and bolus distribution changed relatively little with increased flow. These results suggested that in compensation for paralysis of a hemidiaphragm, a new pattern of inspiratory muscle recruitment developed, involving more rapid contraction of the remaining muscles of inspiration.

Forced Expiratory Volume↗

PubMed2002

Oropharyngeal deglutition in stable COPD.

STUDY OBJECTIVES: The aim of this study was to examine deglutition in stable patients with COPD and lung hyperinflation. DESIGN: Twenty consecutive, eligible COPD patients with an FEV(1) < or = 65% of predicted and a total lung capacity > or = 120% of predicted were enrolled prospectively. INTERVENTION: Patients received a detailed videofluoroscopic evaluation of oropharyngeal swallowing and were compared to 20 age-matched and sex-matched historical control subjects. SETTING: An outpatient pulmonary clinic at a Veterans Affairs Medical Center. MEASUREMENTS AND RESULTS: The mean total lung capacity, functional residual capacity, and residual volume for the patients were 128% of predicted, 168% of predicted, and 218% of predicted, respectively. The mean FEV(1) was 39% of predicted. There was no evidence of tracheal aspiration in either group. The laryngeal position at rest measured relative to the cervical vertebrae was not different between groups. The maximal laryngeal elevation during swallowing was significantly lower in patients with COPD (p < 0.001). Patients with COPD exhibited more frequent use of spontaneous protective swallowing maneuvers such as longer duration of airway closure and earlier laryngeal closure relative to the cricopharyngeal opening than did control subjects (p < 0.05). CONCLUSIONS: We conclude that hyperinflated patients with COPD have an altered swallowing physiology. We suspect that the protective alterations in swallowing physiology (swallow maneuvers) may reduce the risk of aspiration. However, these swallowing maneuvers may not be useful during an exacerbation and may require further research.

Aged↗

PubMed1999

External thoracic restriction, respiratory sensation, and ventilation during exercise in men.

Multiple factors may contribute to the dyspnea associated with restrictive ventilatory disease (RVD). Simple models that examine specific features of this problem are likely to provide insight into the mechanisms. Previous models of RVD utilizing elastic loads may not represent completely the impact on pulmonary and chest wall receptors derived from breathing at low thoracic volumes. The purpose of this study was to investigate the sensory consequences of breathing at low lung volumes induced by external thoracic restriction in an attempt to further elucidate the etiology of dyspnea in this setting. Ten men were studied, with and without an inelastic corset applied at residual volume (restriction resulted in mean reductions in vital capacity, functional residual capacity, residual volume, and forced expired volume in 1 s of 44, 31, 12.5, and 42%, respectively). During 10-min steady-state exercise tests (at a workload set to achieve approximately 65% maximum heart rate), restriction resulted in significant increases, compared with control, in minute ventilation (61 vs. 49 l/min), respiratory frequency (43 vs. 23 breaths/min), and visual analog scale measurements of respiratory discomfort (65 vs. 20 mm). Alveolar hyperventilation (end-tidal PCO2 = 39 vs. 44 Torr for control) and mild O2 desaturation (arterial blood O2 saturation = 93 vs. 95% for control) occurred. Hypoxemia, atelectasis, increased work and effort of breathing, or a decrease in the volume-related feedback from chest wall and/or lungs could be responsible for the increased dyspnea reported. External thoracic restriction provides a useful model to study mechanisms of dyspnea in RVD.

Adult↗

PubMed1979

Lung function in children with recurrent bronchitis.

Lung function was studied in 29 children suffering from recurrent bronchitis (average number of bronchitis attacks per year: 4.2 +/- 0.5). Most of them (73%) were 1--7 years old. The date of exploration in relation to the last acute bronchitis was on average 6 weeks. Lung mechanics, residual functional capacity, blood gases and regional lung function were measured. Most of the children were suffering from some kind of functional disorder; alteration of lung mechanics -- increase of lung resistance (22/29) decrease of dynamic compliance (15/23); increase of functional residual capacity (6/10), non specific bronchial hypersensitivity (12/17); regional ventilatory and perfusion malfunction. These functional disorders could be the first evidence of the bronchial lesions which cause chronic obstructive bronchitis in adults.

Bronchitis↗

PubMed1976

Pulmonary function studies after smoke inhalation.

Pulmonary function studies were performed within 72 hours of injury in seven patients with smoke inhalation injury diagnosed by positive 133Xe scintiphotographs and in eight patients with burns of similar size but with negative 133Xenon scans. The former patients showed decreased peak flow, decreased flow at 25, 50, and 75 per cent of vital capacity, and an elevated pulmonary resistance. In addition, single breath nitrogen tests revealed evidence of maldistribution of ventilation/perfusion abnormalities. Total lung capacity, functional residual capacity, and compliance (both dynamic and static) were similar in the two groups. Pulmonary function studies can be of assistance in evaluating smoke inhalation, estimating the severity, and following the course of patients with this disorder.

Adolescent↗

PubMed2002

Anaesthesia for laparoscopic surgery in paediatrics.

Laparoscopic surgery is an emerging procedure in the treatment of many surgical pathologies. Laparoscopy in the paediatric patient reduces surgical trauma and improves cosmetic RESULTS. Physiological changes during laparoscopic surgery are mainly related to the increased intra-abdominal pressure (IAP) associated with CO2 insufflation of the abdomen, the patient's postural modifications (head-up or head-down) and CO2 absorption and its general effects. Increases in IAP affect both ventilation and circulation. Increased IAP induces a mechanical compression of the diaphragm that reduces pulmonary compliance, vital capacity, functional residual capacity (FRC) and total lung volume. Pneumoperitoneum in children has a major impact on cardiac volumes and function, mainly through the effect on ventricular load conditions. The acute increase in IAP affects both preload and afterload, while the systolic cardiac performance remains unchanged. During anaesthesia for videolaparoscopy it is important not to exceed an intrabdominal pressure of 6 mmHg in newborns and infants and 12 mmHg in older children. In our clinical experience the respiratory, cardiocirculatory and temperature parameters have been slightly influenced during laparoscopy, but have always been maintained within the normal ranges. Laparoscopic videosurgery in newborns, infants and paediatric age group patients can be performed safely and with satisfactory clinical results.

Adolescent↗

PubMed1993

Effects of weight loss on pulmonary function in obese men with obstructive sleep apnoea syndrome.

The effects of long-term behaviour modification of obesity on pulmonary function was studied in eight men with obstructive sleep apnoea syndrome (initial mean body mass index [BMI] 41.8 kg m-2) before and after a mean weight loss of 20 +/- 7 (SD) kg. Mean arterial PCO2 fell from 6.3 +/- 1.2 to 5.5 +/- 0.6 kPa (P < 0.05) and concomitant significant improvements were found in vital capacity, total lung capacity, functional residual capacity and forced expired volume (FEV 1.0). The study suggests that weight loss per se, rather than the method of choice to achieve weight loss, results in clinically significant improvement of pulmonary function in obese men.

Adult↗

PubMed1991

The effect of dead space on inhaled particle deposition.

Mathematical models which have been developed to predict the deposition of particles in the conducting airways of the lung require simplified anatomical models of the dimensions and geometry of the bronchial airways. In order to produce valid deposition predictions, the computed volumes of the conducting airways must be realistic in comparison to anatomical dead space. This requirement must be met even as the developing lung grows to maturity and then undergoes aging. The effect of these age-related changes on predicted particle deposition efficiencies has not been well studied. Numerous authors have suggested that differences in lung volumes (total lung capacity, functional residual capacity, dead space and tidal volume) may account for significant variations between predicted or observed particle deposition but no general age-specific relationship has been proposed. New models are proposed to describe changes in dead space as functions of age and body size, and methods to adjust existing anatomical models to various dead space predictions are given. Also, the effect of these modifications to anatomical models on particle deposition efficiencies are simulated for a variety of breathing patterns for models scaled to represent young children, adults, and aged persons.

Age Factors↗

PubMed2006

Temporal profile of forced expiratory lung function in allergen-challenged Brown-Norway rats.

The Brown-Norway rat is often used to study the allergic pulmonary response. However, relatively little is known about the delayed phase reactions after allergen challenge in this species. To evaluate the temporal changes in lung function and elucidate the mechanisms involved in the delayed phase response, Brown-Norway rats were sensitized and challenged to aerosolized ovalbumin and lung functions were measured by forced expiratory maneuvers and forced oscillation for up to 10 days after a single antigen challenge. Statistically significant (P < 0.05) reductions in inspiratory capacity, forced vital capacity, functional residual capacity, peak expiratory flow and maximum mid-expiratory flow and increases in respiratory system resistance and elastance were seen by 1 to 3 days after ovalbumin challenge that returned to baseline by 10 days. The reductions in lung function after ovalbumin challenge were blocked by the corticosteroid, betamethasone (1 mg/kg, p.o.). Histological evaluation of lung tissue of sensitized rats demonstrated evidence of interstitial pulmonary edema, an increase in tissue eosinophils and an increase in Periodic Acid Schiff-positive cells in the airway epithelium. Bronchoalveolar lavage fluid samples showed large numbers of eosinophils and increased mucin content up to 6 days after antigen challenge. There was also an increase in wet-to-dry lung weight ratio in the lungs of sensitized rats after antigen. These results demonstrate that prolonged reductions in lung function occur after a single antigen challenge in Brown-Norway rats that is probably due to inflammatory processes producing interstitial pulmonary edema, mucus secretion and cellular influx into the lungs.

Allergens↗

PubMed1986

[Consequences of adult brachial plexus paralysis and its surgical treatment on respiratory function].

The authors have studied 22 patients suffering from traumatic brachial plexus injuries and the consequences on respiratory function of paralysis of the diaphragm and other respiratory muscles. They have also studied the effects of some surgical treatment on respiratory function. The patients were divided into three groups: post-traumatic paralysis of the diaphragm (5 cases), patients who had had an intercostal neurotization (11 cases) and patients with paralysis of some respiratory muscles with an intact diaphragm (2 cases). Six tests were performed--vital capacity, total pulmonary capacity, residual functional capacity, airway resistance, maximum expiratory volume per second and airflow at 50 p. 100 of the vital capacity. Respiratory function was decreased by about 50 p. 100 in cases of diaphragmatic paralysis. This finding should be taken into consideration in cases of extensive lesions of the brachial plexus. The effects of intercostal neurotization were minimal when performed in cases with respiratory paralysis, but with an intact diaphragm. They were negligible in the absence of any respiratory paralysis. It is concluded that intercostal neurotization should not be performed in cases with diaphragmatic paralysis. In such cases, other types of neurotization are preferred.

Adolescent↗

PubMed1989

Lung function in essential mixed cryoglobulinemia: a short-term follow-up.

Lung involvement in essential mixed cryoglobulinemia (EMC) has been recently described. In order to assess whether patients with EMC experience an accelerated deterioration of lung function, nineteen patients (17 females, 2 males; 49.6 +/- 6.6 years) underwent a short-term follow-up of lung function, chest X-ray and serologic investigations. Reduction of forced expiratory flows and presence of roentgenologic signs of interstitial involvement were confirmed in the baseline evaluation. In addition, a decrease of diffusing capacity was shown. After a mean interval of 15 months, no significant change in lung function was found, with the exception of decrease in maximal expiratory flow at 50% of forced vital capacity, total lung capacity, functional residual capacity, coefficient of transfer of CO. A slight decrease of hemolitic complement (CH50) and of complement fraction (C3) was also observed. This study suggests that patients with EMC tend to have an involvement of pulmonary interstitial space, possibly related to immune complex deposition, but they do not show a severe decline of lung function. Periodical assessment of lung function and chest X-ray is, however, worthwhile.

Adult↗

PubMed1977

Acute supine respiratory failure due to bilateral diaphragmatic paralysis.

This report documents the first known case of bilateral diaphragmatic paralysis following blunt trauma to the chest. The important role of diaphragmatic function in maintaining ventilation, particularly with the patient in the supine position, is illustrated by the reduced total lung capacity, functional residual capacity, and vital capacity. Severe hypoxemia with the patient in the supine position, was markedly improved by elevation of the patient to 30 degree and was further improved by sitting the patient upright. Following an initial period of acute respiratory failure, the patient was managed acceptably by maintaining an elevated position for sleeping until diaphragmatic function returned, about nine months after the injury.

Accidents, Traffic↗

PubMed1991

Lung volume and distensibility in insulin-dependent diabetes mellitus.

The effect of insulin-dependent diabetes mellitus on pulmonary function was studied in 22 diabetic nonsmokers (11 men) with a mean age of 40 yr (SE, 4 yr) and no history of cardiorespiratory disease. Exponential analysis of static pressure-volume data obtained during deflation of the lungs gave the exponent K, an index of pulmonary distensibility. In the diabetic subjects, mean values for total lung capacity, functional residual capacity, VC, and FEV1 were similar to predicted values. Diffusing capacity, K, and in K did not differ significantly from corresponding values in healthy subjects. The regression of in K on age was significant (R = 0.52; p less than 0.01) and similar to that obtained for 124 healthy subjects. The findings show that insulin-dependent diabetes mellitus does not affect pulmonary function. This study does not support the routine testing of lung function in otherwise well diabetic nonsmokers.

Adult↗