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Results for “Functional Residual Capacity”

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PubMed1988

Effect of laryngeal anesthesia on pulmonary function testing in normal subjects.

Pulmonary function tests (PFT) were performed on 11 normal subjects before and after topical anesthesia of the larynx. The PFT consisted of flow volume loops and body box determinations of functional residual capacity and airway resistance, each performed in triplicate. After the first set of tests, cotton pledgets soaked in 4% lidocaine were held in the pyriform sinuses for 2 min to block the superior laryngeal nerves. In addition, 1.5 ml of 10% cocaine was dropped on the vocal cords via indirect laryngoscopy. PFT were repeated 5 min after anesthesia. Besides routine analysis of the flow volume loops, areas under the inspiratory (Area I) and expiratory (Area E) portions of the loops were calculated by planimetry. Area I, peak inspiratory flow (PIF), as well as forced inspiratory flow at 25, 50, and 75% forced vital capacity (FVC), decreased after anesthesia. Peak expiratory flow decreased after anesthesia, but Area E and forced expiratory flow at 25, 50, and 75% FVC were unchanged. This protocol also was performed in 12 normal subjects with isotonic saline being substituted for the lidocaine and cocaine. In this group, no significant differences were observed when flow volume loop parameters were compared before and after topical application of saline. In 5 spontaneously breathing anesthetized dogs, posterior cricoarytenoid muscle and afferent superior laryngeal nerve activity were recorded before and after laryngeal anesthesia performed with the same procedure used in the human subjects. Laryngeal anesthesia resulted in a substantial decrease or a complete disappearance of afferent SLN activity recorded during unobstructed and obstructed respiration. The data suggest that laryngeal receptors help modulate upper airway patency in man.

Adult↗

PubMed1992

Lung density and lung mass in emphysema.

Mean lung density (dm) and radiologic (VLx) lung volume can be calculated using CT scan data. As many emphysematous patients are overdistended, the analysis of dm alone could be meaningless. However, lung mass (m) can be calculated as the product of dm and VLx. Twenty-four patients suspected of mild or severe emphysema as judged by roentgenographic and physiologic examinations as well as 16 healthy subjects were included in the protocol. They all underwent both a CT scan of the whole lung and functional tests from which the following were derived: airway resistance, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), total lung capacity (TLC), CO transfer capacity, quasi-static compliance at functional residual capacity (FRC), and blood gases. All CT scans were performed at the FRC of each patient. The dm was lower in emphysema patients than in healthy subjects, as m was greater in patients than in healthy subjects; 1,303 +/- 398 g and 997 +/- 133 g, respectively. Although dm values were significantly correlated to FEV1, FEV1/FVC, and TLC, m values were not correlated to any of these functional indices. Unexpectedly, these results show that most patients (22/24) with emphysema have a normal or increased lung mass. Normal or above normal m values might be due to oversecretion in some patients. Nevertheless, the synthesis of new tissue due to chronic inflammation is the most likely explanation that could account for this finding.

Adult↗

PubMed2000

Mechanisms for isolated volume response to a bronchodilator in patients with COPD.

We hypothesized that an altered effect of lung inflation on airway caliber may in part explain the isolated volume response to bronchodilators, i.e., an increase of forced vital capacity (FVC) without change in 1-s forced expiratory volume (FEV(1)). Small-airway caliber was measured by high-resolution computed tomography at functional residual capacity and total lung capacity in five chronic obstructive pulmonary disease patients with an isolated increase of FVC (FVC responders) and five with an increase of both FVC and FEV(1) (FVC-FEV(1) responders) after inhalation of salbutamol. In FVC-FEV(1) responders, the airway diameter increased with the cube root of increase in lung volume but was unchanged or even decreased in four of five FVC responders. FVC responders had more severe emphysema, as inferred from lung function and imaging studies, than FVC-FEV(1) responders. We speculate that longitudinal traction or space competition (Verbeken EK, Cauberghs M, and Van de Woestijne KP, J Appl Physiol 81: 2468-2480, 1996) are possible underlying mechanisms. We conclude that the isolated volume response to bronchodilators is associated with severe emphysema and likely results from an altered effect of lung inflation on airway caliber.

Administration, Inhalation↗

PubMed2001

Respiratory control during independent lung ventilation.

We describe the case of a lung transplant patient with primary graft failure and an emphysematous native lung, who displayed different respiratory rates between the transplanted lung and the native lung. Inflation of the native lung delayed the next inspiratory effort relative to inflation of the denervated transplanted lung. Synchronous inflation of both lungs required more pressure in each lung than when that lung was inflated with the contralateral lung near functional residual capacity, suggesting the two lungs compete for space within the thoracic cavity.

Functional Residual Capacity↗

PubMed2005

Inert gas washout in preschool children.

The multiple-breath inert gas washout (MBW) method is used to measure the efficiency of ventilation distribution in the lungs and to measure the functional residual capacity (FRC). It involves recordings of the concentration of an inert marker gas and respiratory flow at the airway opening when a subject breathes through a sealed facemask or a mouthpiece. The MBW method is particularly useful for lung function testing in preschool children (2-6 years) because it requires only passive cooperation and tidal breathing. The lung clearance index (LCI) is the cumulative expired volume required to clear an inert gas from the lungs, divided by the FRC. The LCI has been shown to be more sensitive than spirometry or airway resistance measurements in detecting lung function abnormalities in young children with cystic fibrosis (CF). The MBW method may be useful also for screening for several other disorders that affect the peripheral airways in children.

Breath Tests↗

PubMedDate not supplied

Evaluation of differential linear transformers as a non-invasive ventilatory method in supine subjects.

We present a new method to measure thoraco-abdominal perimeter variations using differential linear transformers inserted in belts. The high sensitivity (250 mV/mm), the low time drift (1 mV/24 h compared to a 1 V output for a tidal volume), the good frequency response (up to 10 Hz) and low cost (12,000 FF) are the major advantages over other devices. After calibration (using change contribution of thorax and abdomen and the least square method for calculation of volume-motion coefficients), estimated tidal volumes in 23 adults in supine position are within 0.06 +/- 5.17% and changes in functional residual capacity (43-453 ml) are within 3.4 +/- 15.3% when compared with direct spirometry. These results show that the method can be used to monitor ventilation accurately in supine healthy subjects.

Adolescent↗

PubMed1985

Pulmonary physiology of the ferret and its potential as a model for inhalation toxicology.

Physiological measurements were made from anesthetized, tracheotomized, supine male ferrets. Six animals weighing 576 +/- 12 g, had tidal volumes (Vt) of 6.06 +/- 0.30 ml, respiratory frequencies (f) of 26.7 +/- 3.9 min(-1), dynamic lung compliance (CDYN) of 2.48 +/- 0.21 ml cmH2O(-1), pulmonary resistance (RL) of 22.56 +/- 1.61 cmH2O L(-1) sec. Pressure-volume curves from nine ferrets (including the above six) revealed almost infinitely compliant chest walls so that lung and total respiratory system curves were essentially the same. Total lung capacity (TLC) (89 +/- 5 ml) and functional residual capacity (FRC) (17.8 +/- 2.0 ml) were determined by gas freeing the lungs in vivo. The TLC of these ferrets was about the same as in 2.5 kg rabbits. Maximum expiratory flow-volume curves showed peak flows of 10.1 vital capacities (VC) sec(-1) at 75% VC and flows of 8.4 and 5.4 VC sec(-1) at 50% and 25% VC. No particular problems were encountered in making these measurements using conventional techniques available in laboratories capable of making pulmonary function measurements on rats and guinea pigs. Preliminary studies of airways reactivity showed equal increases in pulmonary resistance in response to equivalent challenges of aerosolized carbachol and histamine. Light and electron microscopic studies showed that the airways of ferrets are even more like those of humans than are the dog's. The ease with which physiological measurements can be made and the favorable aspects of the lung anatomy indicate the ferret may be more useful, as well as less expensive, than the dog for use in studies of pulmonary physiology and inhalation toxicology.

Aerosols↗

PubMed1992

Respiratory muscle fatigue does not limit exercise performance during moderate endurance run.

The role of respiratory muscle fatigue in limiting exercise performance in well-trained subjects is still controversial, especially as far as relatively short runs are concerned. To determine the occurrence of respiratory muscle impairment, we studied six well-trained athletes before, during (middle of the run) and after a 17 km run. They were all asked to produce the maximum effort they could during the race. Strength was assessed by measuring maximal inspiratory mouth pressure against close airways (MIP), dynamic lung volumes were monitored using a spirometer. No changes in forced vital capacity (FVC), maximal expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV1) were observed throughout the experiment. This suggested that functional residual capacity and subsequently the initial length of respiratory muscle were unchanged. Respiratory muscle strength did not significantly vary at the different time of measurements (154.8 +/- 20.9 cm H2O at the beginning, 157.5 +/- 23.7 cm H2O after 7.5 km, 155.8 +/- 22.5 cm H2O at the end and 152.3 +/- 17.6 cm H2O after 30 min of recovery). We therefore conclude that respiratory muscle fatigue does not impair the exercise performance of well-trained athletes in a relatively short race. The difference between these results and others reported in literature, could be explained by the different degree of training of the subjects performing the race.

Adult↗

PubMed1993

[Postoperative respiratory function and cholecystectomy by laparoscopic approach].

Open cholecystectomy is associated with characteristic changes in pulmonary function showing a restrictive pattern. Laparoscopic cholecystectomy without opening of the peritoneal cavity could be an alternative in reducing postoperative respiratory dysfunction. Having given their informed consent, 13 healthy ASA1 patients (age: 41 +/- 18 yrs) undergoing laparoscopic cholecystectomy were enrolled in this study, in order to assess their postoperative pulmonary function tests (forced vital capacity [FRC], forced expiratory volume [FEV1], functional residual capacity [FRC]) before operation (T0) and 4 h (T4), 24 h (T24), 48 h (T48) after surgery. Anaesthesia technique was the same associating propofol-atracurium-fentanyl, 50% N2O/O2. Ventilation was adapted to maintain end-tidal carbon dioxide pressure up to 30-35 mmHg. Postoperative analgesic regimen consisted of paracetamol-ketoprofen. Mean length of surgery was 84 +/- 15 min; mean duration of anaesthesia was 110 +/- 24 min. An immediate and harmonious restrictive breathing pattern developed postoperatively. Postoperative FVC measured 65% (T4), 63% (T24), 72% (T48) of preoperative function (p < 0.025); postoperative FEV1 measured respectively 60, 66 and 75% of preoperative function (p > 0.001), without change in FEV1/CV and FRC; a significant hypoxia occurred (T0: 86 mmHg, T4: 80 mmHg, T24: 75 mmHg, T48: 81 mmHg [p < 0.05]). Laparoscopic cholecystectomy resulted in less postoperative respiratory dysfunction than conventional cholecystectomy, as previously reported; this restrictive pattern observed without changes in FRC was similar to that following lower abdominal surgery.

Adult↗

PubMed1991

Effect of microgravity on the respiratory system.

Because the pleural pressure gradient and regional distribution of pulmonary function are gravity dependent, substantial changes may be expected during weightlessness. Although very few measurements have been made during spaceflights, a number of observations during brief periods of weightlessness inside aircraft flying with parabolic trajectories confirm these predictions. Single-breath N2 washouts suggest a marked reduction in the inequality of ventilation distribution seen at 1 G. Similarly, inferences made from cardiogenic oscillations during single-breath washouts suggest a greater uniformity of perfusion during weightlessness. This is supported by changes seen on chest radiographs as well as by more direct measurements of regional blood flow distribution using radioactive iodine-labeled macroaggregates. Vital capacity is only slightly reduced, but functional residual capacity decreases by approximately 10% and maximum expiratory flow rates are slightly decreased, especially at low lung volumes. Weightlessness decreases abdominal girth, increases abdominal compliance, and substantially increases the abdominal contribution to tidal volume during resting breathing. Despite these changes, there does not appear to be any alteration in the temporal pattern of breathing. However, the deposition of inhaled medium-sized aerosol particles is substantially reduced, as predicted by model analyses of gravitational sedimentation. Virtually all these observations describe effects at the very onset of weightlessness. Practically nothing is known of slower functional changes and adaptations to prolonged weightlessness. Systematic repeated measurements during manned spaceflights will hopefully begin to provide some information on this subject in the near future.

Blood Volume↗

PubMed1982

Reduction in resting end-expiratory position of the respiratory system with induction of anesthesia and neuromuscular paralysis.

Resting end-expiratory position (REEP) of the respiratory system was monitored continuously using spirometric recording in eleven patients during transition from consciousness to thiopental hypnosis and following subsequent administration of succinylcholine. REEP decreased following thiopental and was little affected by subsequent relaxant in most patients. A fall in REEP was observed within 30 s after thiopental, and a lower, stable level of REEP was attained within approximately 15-45 s. Mean volume of gas expelled from the lungs was 189 (SE 32) ml BTPS. It is concluded that the previously extensively documented decrease in functional residual capacity associated with anesthesia occurs immediately on induction and requires a short, but finite, time for apparent stabilization.

Adolescent↗

PubMed1990

Pulmonary function in infancy and in childhood following mechanical ventilation in the neonatal period.

Pulmonary function was evaluated in both infancy and childhood in the same 19 prematurely born infants, who required mechanical ventilation (MV) during the neonatal period. Results of our patients were compared with those of control subjects. Upon first evaluation, we found that lung resistance (RL) was significantly elevated (24.85 +/- 6.06 vs. 17.77 +/- 2.39 cmH2O/L/s; P less than 0.01). The mean value of dynamic lung compliance (CLdyn) was low, but the difference compared to controls did not reach significance. From infancy to childhood, elevated RL persisted (9.33 +/- 2.51 vs. 6.52 +/- 1.52 cm H2O/L/s; P less than 0.01), and the decrease of CLdyn became significant (46.86 +/- 12.84 vs. 59.34 +/- 15.68 mL/cmH2O; P less than 0.05). In addition, maximum flow at functional residual capacity was significantly decreased (0.824 +/- 0.284 vs. 1.215 +/- 0.358 L/s; P less than 0.01); whereas pulmonary diffusing capacity for carbon monoxide was similar in the patients (7.62 +/- 2.16 mL/min/mm Hg) and in the controls (8.38 +/- 1.6). Pulmonary dysfunction following premature birth, respiratory distress, and prolonged MV may not resolve from infancy to childhood.

Child↗

PubMed2001

Chest physiotherapy after coronary artery bypass graft surgery--a comparison of three different deep breathing techniques.

The effectiveness of three deep breathing techniques was evaluated in 98 male patients after coronary artery bypass graft surgery in a randomized trial. The techniques examined were deep breathing with a blow bottle-device, an inspiratory resistance-positive expiratory pressure mask (IR-PEP) and performed with no mechanical device. Pulmonary function and roentgenological changes were evaluated. Four days post-operatively there were significantly decreased vital capacity, inspiratory capacity, forced expiratory volume in 1 second, functional residual capacity, total lung capacity and single-breath carbon monoxide diffusing capacity in all three groups (p < 0.0001). No major differences between the treatment groups were found, but the impairment in pulmonary function tended to be less marked using the blow bottle technique. The Blow bottle group had significantly less reduction in total lung capacity (p = 0.01) compared to the Deep breathing group, while the IR-PEP group did not significantly differ from the other two groups.

Aged↗

PubMed1991

Regional deformation of the canine diaphragm.

To follow regional deformation of the diaphragm in dogs, radiopaque markers were implanted under surgical anesthesia into different anatomic regions of the muscle in triangular arrays (approximately 1 cm to a side). After recovery from surgery, changes in area and shape of the triangles were followed with biplane cinefluorography during quiet breathing and during inspiratory efforts against an occluded airway (Mueller maneuvers). From changes in shape of the triangles during contraction, area changes were decomposed into a major direction and magnitude of shortening (Eg1) and a minor length change (Eg2) perpendicular to Eg1, both expressed as a fraction of initial length at end expiration. With the use of these techniques, systematic differences in regional area change were observed in different parts of the diaphragm during inspiratory efforts at different lung volumes. Regional area always decreased during contraction in the crural and midcostal zones of apposition to the rib cage. Area decreased less and often increased during inspiratory efforts in the costal dome near the central tendon and in the costal region near its rib cage insertion. Differences in regional area change were not due to differences in the Eg1 in different parts of the diaphragm but were a consequence of differences in widening of the muscle along Eg2 perpendicular to the direction of Eg1. As lung volume was passively increased above functional residual capacity, regional area decreased in all parts of the diaphragm except in the costal regions near rib cage insertion, where area increased.

Animals↗

PubMed1981

Intrathoracic pressure and volume changes during the spontaneous onset of respiration in babies born by cesarean section and by vaginal delivery.

We studied the first breath of newborn infants delivered by cesarean section. Inspiratory pressure and volume were found to be similar to those in infants born vaginally. However, the expiratory and delivery pressures were found to be smaller. Functional residual capacity was formed less frequently after cesarean section than in the vaginally delivered group.

Cesarean Section↗

PubMed2000

The relationship between gas delivery patterns and the lower inflection point of the pressure-volume curve during partial liquid ventilation.

STUDY QUESTION: To determine whether a positive end-expiratory pressure (PEEP) level equivalent to the lower inflection point (LIP) could be identified by evaluation of the airway pressure, flow (f1. gif" BORDER="0">), and volume vs time waveforms during partial liquid ventilation (PLV). DESIGN: Prospective application of PEEP during PLV in a healthy animal model. SETTING: University hospital animal laboratory. PARTICIPANTS: Five healthy sheep weighing 30 kg each. INTERVENTIONS: The sequential application of 0 to 20 cm H(2)O PEEP in 2.5-cm H(2)O steps during PLV with both pressure and volume ventilation. MEASUREMENTS: Analysis of the pressure, volume, and f1. gif" BORDER="0"> waveforms as PEEP is sequentially increased. RESULTS: At 0 cm H(2)O PEEP, VT was markedly reduced compared with PEEP VT at > or = 7.5 cm H(2)O (p < 0.05) in pressure control ventilation (PCV), and peak inspiratory pressure minus PEEP was markedly increased compared with PEEP at > or = 5.0 cm H(2)O (p < 0.05) in volume control ventilation. At 10 cm H(2)O PEEP, all waveforms began to stabilize, and no significant differences in any variable assessed were measured at > 12.5 cm H(2)O PEEP. CONCLUSIONS: The application of PEEP during PLV markedly alters airway waveforms. Low PEEP decreases VT in PCV and increases airway pressure in VCV. The PEEP level equal to the LIP during PLV can be grossly estimated from airway waveforms. PEEP at > or = 10 cm H(2)O is needed to normalize gas delivery to functional residual capacity in the uninjured lung that is partially filled with perfluorocarbon.

Air Pressure↗

PubMed1985

Short and long term reproducibility of responsiveness to inhaled histamine: Rt compared to FEV1 as measurement of response to challenge.

Repeatability (123 min) and reproducibility (65 days) of response to inhaled histamine were tested in a selected group of stable asthmatics and non-asthmatics by means of FEV1 and breathing resistance (Rt) determined by the interruptor method. Variation in prechallenge FEV1 and Rt was kept within a +/- 10% and +/- 40% range, respectively. We found the PC20-FEV1 highly repeatable after 123 min. The 95% confidence interval for a single determination was the measured value +/- 1.72 two-fold concentration differences. Reproducibility was significantly lower (p less than 0.05). Both repeatability and reproducibility of PC30-Rt were significantly lower than that of PC20-FEV1. Interruptor method determined PC30-Rt was found repeatable within 4 two-fold concentration differences which is not acceptable for clinical and research purposes. The poor repeatability of PC30-Rt could be due to changes in functional residual capacity during challenge.

Adolescent↗

PubMed1983

Sedation and respiratory mechanics in man.

The effects of sedation with halothane, enflurane or midazolam on respiratory mechanics and lung volumes were studied in young healthy volunteers, in the supine position. Functional residual capacity increased with halothane sedation, but was unchanged with sedation produced by enflurane or midazolam. Sedation with halothane and enflurane, but not midazolam, tended to increase lung static recoil pressure. Total lung capacity was decreased during sedation with midazolam. No evidence was found that sedation with these three agents increased airway resistance. These findings imply that changes in respiratory mechanics induced by the residual effects of anaesthetic agents are unlikely to contribute significantly to the impairment in pulmonary gas exchange which may occur in the period immediately after operation.

Adult↗