SEARCH · PubMed Health

Results for “Functional Residual Capacity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMedDate not supplied

Pulmonary mechanics generated by positive end-expiratory and continuous negative pressure.

Pulmonary function measurements were studied on equivalent levels of positive end-expiratory pressure (PEEP) and continuous negative pressure (CNP) while controlling for transpulmonary pressure (TPP). Four adult rabbits were anesthetized, instrumented, and ventilated with intermittent mandatory ventilation by using peak inspiratory pressure (PIP) of 16 cm H2O, PEEP 0 cm H2O, CNP 0 cm H2O, inspiratory time 0.3 seconds, rate 20/min, and fraction of inspired oxygen of 0.3. Subsequently, equal amounts of PEEP and CNP were alternated for 15-minute ventilation periods. PIP was changed to approximate the TPP in each PEEP/CNP pair. There was a significant decrease in PCO2 and increase in pH, mechanical tidal volume, minute ventilation, functional residual capacity, and total dynamic compliance on CNP. These differences could not be explained by changes in TPP.

Animals↗

PubMed1994

Anaesthesia and chest wall function.

The effects of anaesthesia and surgery on the chest wall may be responsible for impaired gas exchange and other pulmonary complications during the perioperative period. Current evidence supports the following sequence of events. Anaesthesia changes the shape and motion of the chest wall, either by changing the amount of tonic and phasic activity of the respiratory muscles (anaesthesia with spontaneous breathing) or by eliminating the activity entirely (paralysis with mechanical ventilation). These primary changes in chest wall function lead to secondary changes in lung function, including the formation of dependent lung atelectasis. Recent advances in imaging of the thorax have called into question traditional understanding of the mechanisms by which anaesthesia alters chest wall function. For example, it is now apparent that anaesthesia reduces the functional residual capacity not by changing the position of the diaphragm, but rather by affecting the rib cage, and, perhaps, the volume of intrathoracic blood. The effects of anaesthesia and surgery on postoperative chest wall function may be lessened by regional analgesia and the use of laparoscopic surgical techniques. However, it is not yet clear that this improvement is associated with a reduction in the incidence of pulmonary complications.

Anesthesia↗

PubMed1988

Functional characteristics of canine costal and crural diaphragm.

We estimated the in situ force-generating capacity of the costal and crural portions of the canine diaphragm by relating in vitro contractile properties and diaphragmatic dimensions to in situ lengths. Piezoelectric crystals were implanted on right costal and left crural diaphragms of anesthetized dogs, via midline laparatomy. With the abdomen reclosed, diaphragm lengths were recorded at five lung volumes. Contractile properties of excised muscle bundles were then measured. In vitro force-frequency and length-tension characteristics of the costal and crural diaphragms were virtually identical; their optimal force values were 2.15 and 2.22 kg/cm2, respectively. In situ, at residual volume, functional residual capacity (FRC), and total lung capacity the costal diaphragm lay at 102, 95, and 60% of optimal length (Lo), whereas the crural diaphragm lay at 88, 84, and 66% of Lo. Muscle cross-sectional area was 40% greater in costal than in crural diaphragms. Considering in situ lengths, cross-sectional areas, and in vitro length-tension characteristics at FRC, the costal diaphragm could exert 60% more force than the crural diaphragm.

Animals↗

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↗

PubMed1987

A model of the regional uptake of gaseous pollutants in the lung. II. The sensitivity of ozone uptake in laboratory animal lungs to anatomical and ventilatory parameters.

An O3 dosimetry model is used to simulate the local absorption of O3 in the lower respiratory tract of rats and guinea pigs. The model takes into account lower respiratory tract anatomy, transport in the lumen and air spaces, and transport and chemical reactions in the mucous and surfactant layers and in the underlying tissue and capillaries. For each species two anatomical models were used to investigate their influence in predicting absorption. Results with all four anatomical models and various ventilatory parameters showed a qualitative similarity in the shape of the dose versus airway number curves but significant differences in predicted percentage total and percentage pulmonary uptake. The percentage uptake was also sensitive to breathing frequency and tidal volume. Rat lobe models were used to study absorption in lobes and show that O3 tissue dose in centriacinar regions decreases with increasing distance from the trachea. The effect on results of values used for functional residual capacity and of values used for the chemical rate constants for O3 reactions in mucous were explored. Results differed quantitatively but not qualitatively.

Air Pollutants↗

PubMed1984

Postoperative pulmonary function in children. Comparison of scoliosis with peripheral surgery.

We measured lung volumes, forced expirograms, and arterial blood gases in 2 groups of elective pediatric surgical patients (mean age, 11.4 +/- SD 2.8; n = 11, 12 operations) the day prior to surgery (control) and between the first and eighth postoperative days. The patients were Group I: peripheral surgery (n = 6) and Group II: reconstructive surgery for scoliosis (n = 5). The preoperative lung volumes and forced expiratory volume in one second were within the predicted normal range in both groups, except for a reduction in total lung capacity (TLC) and vital capacity (VC) in Group II. The postoperative lung volumes in Group I were not significantly different from the preoperative volumes. In group II, on postoperative Days 2 and 3, the lung volumes as a percent of preoperative volumes (mean +/- SEM) were VC, 44 +/- 11; functional residual capacity (FRC), 81 +/- 6; residual volume, 124 +/- 10; TLC, 61 +/- 10. Although the mean FRC returned to the preoperative volume by postoperative Days 5 and 6, the VC and its components remained reduced on postoperative Days 5, 6, and 8. We conclude that postoperative lung volume abnormalities are related to the site and magnitude of surgery and associated phenomena, such as pain, and preoperative respiratory function abnormalities.

Adolescent↗

PubMed1977

A new technique for evaluating nitrogen washout efficiency.

Nitrogen washout curves resulting from open circuit N2 washouts of unsedated human and canine subjects were constructed by plotting the breath-by-breath end-expiratory N2 fraction (Fn2) against breath number on a semilog scale. Curves were analyzed graphically, and the slope of the 2nd of the 3 components was expressed by B 1/2, the number of breaths required to reduce Fn2 to half of its original value. The magnitude of B 1/2 was directly proportional to the value of functional residual capacity (FRC) divided by tidal volume (Vt). The quantity B 1/2 (FRC/Vt) was relatively constant within an individual regardless of FRC or Vt and was named the nitrogen dilution constant (NDC). Means and ranges of Vt, FRC, B 1/2, and NDC were determined for normal human subjects and Beagle dogs. The NDC varied less among and within subjects than other simple indices of washout efficiency. It was also more sensitive than other indices in detecting age-related loss of washout efficiency. The use of NDC in evaluating N2 washout of subjects with interstitial lung disease was demonstrated.

Adult↗

PubMed1979

The effects of early pneumonectomy on the remaining pulmonary parenchyma.

To determine the age-related response of the remaining pulmonary parenchyma to lung resection, a matched set of 24 purebred beagle dogs underwent pneumonectomy at 6 to 10 weeks of age (group I) or at 1 year of age (group II). Eight unoperated adult beagles served as controls (group III). One year after pneumonectomy, pulmonary hemodynamics in group I were the same as those in older animals shortly after pneumonectomy and in normal control animals. Functional residual capacity, total lung capacity, single breath diffusing capacity for carbon monoxide, and static lung compliance were measured in all three groups while anesthetized and intubated. Lung volumes and diffusion capacity for carbon monoxide in group I did not differ significantly from those of control animals. Group I animals did have a lower lung compliance than the control group, but significantly greater than the group II adult pneumonectomy dogs. The adult pneumonectomy dogs (group II) had significantly lower values for lung volumes, diffusion capacity, and compliance when compared to the control group. Arterial blood gases were not significantly different among the groups. It is concluded that beagles undergoing early pneumonectomy have an increase of alveoli beyond the normal complement in the remaining lung with concomitant remodeling of the pulmonary capillary bed resulting in normal lung volumes, diffusing capacity, and gas exchange.

Age Factors↗

PubMed1996

Changes in chest wall compartment volumes on induction of anaesthesia with eltanolone, propofol and thiopentone.

Changes in the expiratory dimensions of the rib cage and abdomen on induction of anaesthesia with eltanolone, propofol and thiopentone were measured in 76 patients using respiratory inductance bands. Calibration of the respiratory inductance plethysmograph was by simultaneous flow measurement with a pneumotachograph. Movement of the vertebral column was restrained with a rigid mattress to allow volume change to be estimated more accurately from rib cage and abdominal dimensions. Rib cage volumes decreased by a median of 125 ml, while the median change in the abdominal compartment was 0. These findings suggest that a reduction in rib cage volume may contribute to the decrease in functional residual capacity after induction of anaesthesia, but that changes in the diaphragmatic-abdominal compartment are not important.

Abdomen↗

PubMed1989

An evaluation of the multiple-breath nitrogen washout as a pulmonary function test in dairy cattle.

Multiple-breath nitrogen washouts (MBNW) were performed with 21 adult dairy cows (seven normal cows tested on two days each, four clinically normal cows tested on six days, and ten cows with respiratory disease tested on one day each). The functional residual capacity (FRC), lung clearance index (LCI), Becklake index (BI), mixing ratio (MR), pulmonary N2 clearance delay (PCD), index of distribution of inspiration (IDI) and ventilatory efficiency (EFF) were calculated for each MBNW. The LCI, MR, PCD, IDI and EFF were calculated at an end-tidal N2 concentration of 3% (FETN2,3%) and the end-tidal N2 concentration of the final breath of the MBNW (FETN2,fb), while BI was calculated and EFF was also calculated at FETN2 = 8% (i.e. after washout of 90% of the N2 in the lung). All of the MBNW were irregular due to breath-to-breath variability in the breathing pattern of cows and variability in FRC. The within day coefficients of variation for FRC, LCI, MR, IDI, EFF3% and EFFfb were less than 10%, but in the four cows tested on six days there was significant day-to-day variability for individuals for FRC, LCI, BI, MR, PCD and IDI. The shape of the MBNW curves differed between the normal cows and those with respiratory disease. The FRC, EFF3% and EFFfb were the most sensitive indices in detecting the cows with respiratory disease, and when EFF3%, EFFfb or FETN2fb, was used in conjunction with FRC it was possible to detect all of the cows with respiratory disease.

Animals↗

PubMed1994

Scanning electronmicroscopic morphometry of emphysema in humans.

We quantitated the holes in alveolar walls in 11 nonemphysematous lungs and in 11 lungs with mild emphysema, all of which were removed at surgery. We found that in the nonemphysematous lungs, 94.1% of the holes were smaller than 10 microns in diameter and only 0.2% were larger than 20 microns. In the lung parenchyma distant from emphysema, both the maximum diameter of the holes and the diameter of alveoli increased. In the parenchyma between emphysema, the areas of alveolar walls represented by holes also increased, as did the average hole area and number of holes per alveolus. We found that alveolar holes in the regions between emphysema correlated better with pulmonary function tests than did those in regions distant from emphysema. The maximum diameter of holes and the number of holes per alveolus correlated with functional residual capacity, residual volume, closing capacity expressed as a proportion of total lung capacity (CC/TLC), and static recoil pressure of the lung at TLC. Emphysema correlated with CC/TLC and with the transpulmonary pressure at 90% TLC. Bronchiolar lesions were not related to pulmonary function tests. Our data provide support for the hypothesis that the tissue surrounding emphysematous lesions contributes to loss of recoil.

Functional Residual Capacity↗

PubMed1987

Serial determination of pulmonary function in infants with chronic lung disease.

Pulmonary function was measured in 39 infants with chronic lung disease who had required mechanical ventilation starting during the first week of life for a median of 9 days (range 1 to 46 days) and supplemental oxygen for a median of 48 days (range 28-162 days). Their mean birth weight was 1140 g (range 550 to 2325 g), and mean gestational age 29.8 weeks (range 26 to 37 weeks). Ventilation was measured by pneumotachography, esophageal pressure through a water-filled feeding tube, and functional residual capacity (FRC) by a modified nitrogen washout technique. Lung compliance, pulmonary conductance, and FRC were determined at 1, 3, 6, 12, 18, 24, and 36 months after birth. Pulmonary function was also determined in 40 normal children, ranging in age from neonates to 5 years, who served as controls. In infants with chronic lung disease, growth in weight and length followed the 10th to 25th percentiles of the normal curve. Minute ventilation and respiratory effort remained elevated throughout the follow-up. FRC per kilogram of body weight was decreased at 1, 3, and 6 months after birth, but thereafter was in the normal range. FRC increased in proportion to weight at the same rate as in the controls. Lung compliance was only half of normal at 1 month, increased with growth in close correlation with weight, and was approximately 80% of normal at the end of follow-up. Pulmonary conductance was 50% of normal at 1 month, increased little during the first 6 months, but reached 85% of normal at 3 years of age. There was no evidence of gas trapping. These results indicate that in infants with chronic lung disease after mechanical ventilation, lung volume increases normally, probably by formation of new alveoli, which also leads to improvement in lung compliance. Airway growth is slow during the first 6 months after birth, but the subsequent faster growth leads to conductance values close to normal at 3 years of age.

Body Weight↗

PubMed1989

Effects of water temperature on pulmonary volumes in immersed human subjects.

Pulmonary volumes and capacities have been measured at three water temperatures (Tw = 25, 34, 40 degrees C) in standing subjects immersed up to the shoulders. The comparison of data obtained in air with those obtained in thermoneutral immersion (Tw = 34 degrees C) confirms the results previously published in several studies. The comparison of data obtained in immersion at different Tw shows: 1. A significant decrease in vital capacity (VC) with bath temperature (VC 40 degrees C greater than VC 34 degrees C greater than VC 25 degrees C). The same decrease is observed in the inspiratory reserve volume (IRV) while the expiratory reserve volume (ERV), the residual volume (RV) and the functional residual capacity (FRC) do not vary. 2. A significant decrease in maximum breathing capacity (MBC) with bath temperature (MBC 40 degrees C greater than MBC 25 degrees C). 3. A significant increase in tidal volume (VT) in cold or hot water compared to thermoneutral water (VT40 degrees C greater than VT34 degrees C; VT34 degrees C less than VT25 degrees C) during quiet breathing. Breathing frequency does not change, thus ventilation (V) follows the same evolution as VT. The relative abdominal (ABD) contribution to VT, estimated by a double belt inductance plethysmograph, is reduced at Tw = 25 degrees C but unchanged at Tw = 40 degrees C compared to thermoneutral bath. Beside variations in the metabolic state, the variations of the pulmonary volumes as a function of Tw are estimated to be mainly due to alterations in respiratory muscles functioning.

Adult↗

PubMedDate not supplied

Reference values for pulmonary tissue volume, membrane diffusing capacity, and pulmonary capillary blood volume.

Pulmonary tissue volume (Vti), carbon monoxide diffusing capacity, membrane diffusing capacity, pulmonary capillary blood flow and pulmonary capillary blood volume were measured in ninety (54 men and 36 women) healthy lifetime nonsmokers using an inert gas rebreathing technique. Prediction equations were generated using multiple linear regressions with height and age as the independent variables. Normalizing the data by dividing by functional residual capacity eliminated all sex differences. In contrast to the other variables, normalized pulmonary tissue volume did not correlate with any of the independent variables tested. Therefore, an average normalized Vti value can be recommended as a reference value

Adult↗

PubMed2000

[Several aspects of respiratory function testing in children].

Some practical aspects of respiratory function testing (RFT) are reviewed with special interest on applications in preschool children. RFT may be used for diagnostic, management and follow up purposes. Children may benefit from RFT in a variety of pathological situations. Asthma and other obstructive airways diseases certainly represent the most frequent conditions. Vital Capacity and Forced Expiratory Volume in one second (FEV1) may usually be obtained from age 7 on. In smaller children, the forced expiratory manoeuvre is much less successful. Non invasive measurements such as respiratory resistance (Rrs) or specific airway resistance (sRaw) may be used. Rrs is usually measured by the interrupter technique or the forced oscillation technique and sRaw by body plethysmography, not requiring the estimation of thoracic gas volume. Because much variability is introduced by the upper airways, these parameters are less suited than FEV1 to establish the degree of baseline airway obstruction. On the other hand, Rrs and sRaw may quantify reversibility of airway obstruction and/or bronchial hyperresponsiveness. Lung hyperinflation may be identified by the assessment of Functional Residual Capacity (FRC) with a dilution method. More generally lung growth may be followed up in longitudinal studies of FRC even in small children. More work is needed to standardize RFT techniques and indications in the preschool child.

Age Factors↗

PubMed1999

[Measurement and clinical use of recoil pressure of the respiratory system].

Using the principle that the difference of MIP (maximal inspiratory mouth pressure) between RV (residual volume) and FRC (functional residual capacity) equals Prs (recoil pressure of the respiratory system) at RV, we performed the measurement of Prs at RV in 20 normal subjects, 90 patients with COPD (chronic obstructive pulmonary disease) and 15 patients with ILF (interstitial lung fibrosis). We also performed the correlation analysis of Prs at RV and RV/TLC (total lung capacity) %. The results indicated the Prs values at RV (-2.8 +/- 0.5 kPa) in normal subjects measured in this manner was in accord with the values reported by other authors abroad. The Prs in patients with emphysema decreased and it was highly and negatively correlated with RV/TLC% (r = -0.872), but the Prs in patients with ILF was increased. The results suggest that this method for measurement of Prs is simple, reliable, and clinically useful.

Aged↗

PubMed2004

Respiratory function in pregnancy at sea level and at high altitude.

OBJECTIVE: To determine the effect of pregnancy on respiratory function in a non-Caucasian group and determine whether there was an interaction between pregnancy and altitude of residence. DESIGN: Prospective cross sectional study. SETTING: Antenatal clinics in Peru, at sea level in Lima and at high altitude in Cerro de Pasco. SAMPLE: Peruvian women with singleton pregnancies; 122 living at sea level and 192 living at 4300 m altitude in the Peruvian Andes. At each location, 19 non-pregnant women were also studied. METHODS: Respiratory function was measured in pregnant and non-pregnant women living at sea level and at 4300 m. MAIN OUTCOME MEASURES: Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEFR), total lung capacity (TLC), inspiratory capacity (IC), residual volume (RV), expiratory residual volume (ERV) and functional residual capacity (FRC). RESULTS: At sea level, RV and TLC were higher in the third compared with the first trimester (P < 0.05). At high altitude, FEV1 (P < 0.01), ERV (P < 0.01) and FRC (P < 0.01) were lower in the third compared with the first trimester. Pregnant and non-pregnant women at high altitude were 4 cm shorter (P < 0.0001) and had larger lung volumes (P < 0.01); their total lung capacities were approximately 1 L greater than women living at sea level (P < 0.0001). CONCLUSION: These results suggest that the effect of pregnancy on the respiratory function of healthy women is influenced by altitude of residence.

Altitude↗

PubMed1990

Effective bronchodilator treatment by a simple spacer device for wheezy premature infants.

Ten preterm infants with recurrent respiratory symptoms (median gestational age 30 weeks) were entered into a non-randomised placebo controlled trial of bronchodilator treatment at 12.5 months of age. The infants had coughed or wheezed, or both, on at least four days a week for the past month. The infants received either placebo or 500 micrograms terbutaline from an inhaler using a coffee cup as a spacer device. Each treatment was maintained for two weeks, first placebo then active drug. The symptom score was reduced by 65% during the active treatment period compared with the placebo period and this was associated with a 32% improvement in lung function, reflected in an increase in functional residual capacity. We conclude that inhaled bronchodilator treatment given with a simple spacer device is useful for preterm infants with recurrent respiratory symptoms in the first two years of life.

Bronchodilator Agents↗