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Results for “Functional Residual Capacity”

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PubMed1992

Pulmonary function tests after whole-lung irradiation and doxorubicin in patients with osteogenic sarcoma.

PURPOSE: Because of the scarcity of information regarding long-term follow-up of pulmonary function after whole-lung irradiation, a prospective study was started at the University of Florida in 1979 to evaluate pulmonary function after treatment with whole-lung irradiation and doxorubicin in patients with osteogenic sarcoma. PATIENTS AND METHODS: Between 1979 and 1984, 57 osteogenic sarcoma patients with no evidence of metastatic disease at diagnosis received adjuvant therapy consisting of whole-lung irradiation (with the heart shielded) followed by Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH). The whole-lung irradiation schema was 1,600 cGy in 10 fractions with 8-MV x-rays via anterior and posterior fields. This was followed by five cycles of Adriamycin for a total dose of 450 mg/m2. Pulmonary function tests (PFTs) consisting of spirometry, lung volumes, and diffusing capacity were obtained before the whole-lung irradiation, at 6 and 12 months after irradiation, and at yearly intervals thereafter. RESULTS: At the time of analysis, 28 of the 57 patients were available for study, with a mean follow-up of 42 months (range, 6 to 77 months). Follow-up pulmonary function testing revealed decreased forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1) during the first 6 to 12 months after whole-lung irradiation. These values returned to baseline during the second-year posttherapy and remained at baseline throughout the remainder of the follow-up period. Changes in lung volumes demonstrated a similar early trend, with significant decreases in total lung capacity (TLC) and functional residual capacity (FRC) at 6 to 12 months. These changes, however, did not improve significantly during the remainder of the follow-up period. Diffusing capacity of the lungs for carbon monoxide (DLCO) also reached a nadir at 6 to 12 months after whole-lung irradiation, with resolution by 2 years and maintenance of at least baseline values for the remainder of the follow-up period. CONCLUSIONS: Treatment with whole-lung irradiation and Adriamycin, as given in this study, caused no significant sequelae, as demonstrated by pulmonary function testing during the mean follow-up period of 42 months, although a mild, transient restrictive ventilatory defect occurred at 6 to 12 months after treatment.

Adolescent↗

PubMed1992

Volume infusion produces abdominal distension, lung compression, and chest wall stiffening in pigs.

The effect of severe generalized edema on respiratory system mechanics is not well described. We measured airway pressure, gastric pressure, and four vertical pleural pressures in 13 anesthetized paralyzed pigs ventilated in the upright position. Pressure-volume relationships of the respiratory system, chest wall, and lung were measured on deflation from total lung capacity to residual volume and during tidal breathing both before (control) and 50 min after one of two interventions. In one series of experiments, a volume equal to 15-20% of the pig's body weight was infused intravenously. In a second series, a balloon was placed in the peritoneal space to distend the abdomen to the same gastric pressures as achieved in the first series. Measurements were compared before and after either abdominal balloon inflation or volume infusion. Volume infusion increased the pleural pressure in dependent lung regions, decreased both total lung capacity (34%) and functional residual capacity (62%) (both P less than 0.05), and markedly shifted the respiratory system and chest wall pressure-volume curves to the right, but it only moderately affected the lung deflation curve. Tidal compliances of the respiratory system, chest wall, and lung decreased 36, 31, and 49%, respectively (all P less than 0.05). The effect of abdominal balloon inflation on respiratory system mechanics was similar to that of volume infusion. We conclude that infusing large volumes of fluid markedly alters chest wall mechanics, mainly by causing abdominal distension that prohibits descent of the diaphragm.

Abdomen↗

PubMed1994

High-frequency jet versus conventional ventilation in infants undergoing Blalock-Taussig shunts.

Nine infants undergoing modified Blalock-Taussig shunts were randomized to both high-frequency jet ventilation (HFJV) and conventional ventilation (CV). Vital signs, blood gases, mean airway pressure, lung mechanics, functional residual capacity, and lung movement were compared on both modes of ventilation keeping peak inspiratory and expiratory pressures constant. The mean airway pressure was lower on HFJV than on CV (8.5 versus 10.9 cm H2O). Arterial partial pressure of oxygen was greater on HFJV than on CV (55 versus 46 mm Hg), arterial partial pressure of carbon dioxide was lower on HFJV than on CV (28 versus 37 mm Hg), whereas compliance (0.54 versus 0.56 mL.cm H2O-1.kg-1). resistance (110 versus 95 cm H2O/L.s), and functional residual capacity (23 versus 22.5 mL/kg) remained the same. Lung movement and degree of retraction necessary for surgical exposure as evaluated by an independent observer was less with HFJV compared with CV. Compared with CV during the creation of Blalock-Taussig shunts, HFJV provides better gas exchange at lower mean airway pressure with similar lung function, lung volume, and hemodynamics.

Airway Resistance↗

PubMed1989

Results of a prospective study evaluating the effects of mantle irradiation on pulmonary function.

Thirty patients with Stages I-III Hodgkin's disease receiving mantle irradiation were prospectively evaluated prior to therapy with spirometry, lung volumes, and tests of diffusing capacity (DLCO). Follow-up examinations were performed at 3, 6, and 12 months and then yearly. Sixteen patients had Hodgkin's disease involving the mediastinum at presentation, 10 were smokers, and 16 received either preirradiation or postirradiation chemotherapy. Mantle doses ranged between 2300 cGy and 4000 cGy (mode of 3750 cGy) given at 150 cGy to 170 cGy tumor dose per day with split-course technique. Pulmonary function test results were translated to percent change from predicted values obtained from normal standards for each age, sex, race, and height. These percent changes were then analyzed as a linear function of time. Twenty patients have been tested greater than or equal to 4 years after treatment with a median time from treatment to last pulmonary function test of 8 years. Changes over time in spirometry included an early, mild decrease in both forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1), which returned to baseline by 2 years and then gradually decreased to a 10-15% deficit as compared with predicted values at 6-10 years. Additionally, there was a very slight decrease in FEV1/FVC beginning at 1 year and gradually increasing to an 8% deficit at 6-10 years. Changes over time in lung volumes included a mild nadir of total lung capacity (TLC) and functional residual capacity (FRC) at 6 months to a year, which returned to baseline at 2-4 years and then gradually dropped to a 5-10% deficit at 6-10 years. Mean DLCO for the study group was 20% below predicted values prior to treatment and dropped to a low of 30% below predicted at 6 months following treatment, then gradually returned to baseline by 4 years and showed continued improvement to an overall deficit of approximately 10% at 6-10 years. With the exception of FEV1/FVC, the changes noted in spirometry and lung volumes were of insufficient degree to be classified as abnormal. The decrease in FEV1/FVC is indicative of a significant and progressive obstructive ventilatory defect. The effects on pulmonary function tests of smoking, the presence of mediastinal involvement by Hodgkin's disease, and exposure to chemotherapy were assessed by statistical analysis. No subsets of patients demonstrated consistent evidence of a restrictive ventilatory defect expected after irradiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1997

Mature pulmonary lobar transplants grow in an immature environment.

OBJECTIVE: Mature lobar transplantation will increase the pediatric donor organ pool, but it remains unknown whether such grafts will grow in a developing recipient and provide adequate long-term support. We hypothesized that a mature pulmonary lobar allograft implanted in an immature recipient would grow. METHODS: We investigated our hypothesis in a porcine orthotopic left lung transplant model using animals matched by the major histocompatibility complex to minimize the effects of chronic rejection. Twenty-three immature animals (< 12 weeks of age and < 10 kg total body weight) received either sham left thoracotomy (SH control, n = 4), left upper lobectomy to study compensatory growth (UL control, n = 4), age-matched immature whole left lung transplants (IWL TXP, n = 6), mature (donor > 1 yr in age and > 40 kg in total body weight) left lower lobe transplants (MLL TXP, n = 5), or mature left upper lobe transplants (MUL TXP, n = 4). Twelve weeks after implantation, functional residual capacity of the left lung was measured and arterial blood gas samples were obtained after the native right lung had been excluded. The graft was excised and weighed, and samples for microscopy and wet/dry ratios were collected. RESULTS: Initial and final graft weights were as follows: IWL TXP group (34.6 +/- 1.5 and 107.8 +/- 5.9 gm, p < 0.0001), MLL TXP group (72.4 +/- 6.8 and 111.4 +/- 8.7, p < 0.001), and MUL TXP group (32.8 +/- 1.3 and 92.8 +/- 7.1 gm, respectively, p < 0.004). No significant differences between groups were demonstrated when functional residual capacity, wet/dry ratios, or oxygenation were compared. Immunohistochemical staining for the nuclear antigen Ki-67 demonstrated dividing pneumocytes. CONCLUSIONS: We conclude that a mature lobar graft implanted into an immature recipient grows by pneumocyte division in this model. Mature lobar transplants can be expected to grow and provide adequate long-term function in developing recipients.

Aging↗

PubMed2000

Effect of preoperative hyperinflation on static lung volumes after lung transplantation.

It is still not known whether persistent increases in functional residual capacity (FRC) and residual volume (RV) after lung transplantation are due to preexisting hyperinflation. Therefore, the aim of this study was to determine the effects of chronic lung hyperinflation on static lung volumes after heart/lung (HLT) and bilateral lung transplantation (BLT). Static lung volumes were measured in 33 patients before and at 6 month intervals for up to 3 yrs after HLT (n=25) or BLT (n=8). The preoperative diagnosis was cystic fibrosis in 25 patients and other chronic hyperinflated lung diseases in eight patients. After surgery, total lung capacity returned to predicted normal values but FRC and RV remained greater than expected for either the recipient or the donor. At 1 yr after surgery, mean+/-SD FRC and RV were 130+/-18% and 151+/-34% of the predicted values for the recipient (p<0.001), and these figures did not change significantly over time. Similar abnormalities were found in patients with and without cystic fibrosis. After transplantation for lung diseases producing chronic hyperinflation, there is a persistent increase in functional residual capacity and residual volume. This alteration is present in patients operated on for diseases developed in both childhood and adulthood and is not recovered over time. It may be due to irreversible changes in the structure of the ribcage.

Adult↗

PubMed1992

Natural surfactant instilled in premature lambs increases lung volume and improves ventilation homogeneity within five minutes.

The immediate effects on lung volume, ventilation homogeneity, and lung mechanics of tracheal instillation of surfactant were studied in premature lambs, gestational age 120-122 d, with respiratory distress syndrome. Six lambs received surfactant by tracheal instillation 25 min after delivery by cesarean section; five received only vehicle and served as controls. The lambs were studied for 60 min thereafter. Functional residual capacity was measured with a computerized tracer gas washin-washout technique using sulfur hexafluoride as tracer gas. A measure of ventilation inhomogeneity (pulmonary clearance delay) was also calculated from the washout curves. Pressure-volume curves were studied with an interrupter technique during deflation of the lungs from an airway pressure of 30 cm H2O. In the surfactant group, arterial oxygenation and ventilation homogeneity improved within 5 min of giving surfactant; major increases in functional residual capacity, vital capacity, and compliance occurred within 5 to 20 min and were followed by gradual further improvements. The pressure-volume curve thus increased in amplitude and became steeper, but the lung volumes at various inflation pressures, and compliance, remained constant when expressed as fractions of total lung capacity volume. It is concluded that an improvement in lung volume, respiratory mechanics, and ventilation homogeneity occurs very soon after surfactant instillation and that there is a phase of successive further improvement over the next hour. Although the amplitude of the pressure-volume curve varied considerably, its basic shape varied little. This suggests that opening of new distal airways by surfactant predominated over changes in the mechanics of already aerated lung regions.

Animals↗

PubMed1998

Resistive inspiratory muscle training in subjects with chronic cervical spinal cord injury.

OBJECTIVE: To determine whether pulmonary function, respiratory muscle strength, and dyspnea can be improved in individuals with chronic cervical spinal cord injury (SCI). STUDY DESIGN: Ten subjects participated in an 8-week resistive inspiratory muscle training (IMT) program for 15 minutes twice daily. Spirometry, lung volumes, maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), and dyspnea were measured at baseline, week 4, and week 8. Six months after the study, spirometry, MIP, and MEP were re-measured in a subgroup of the original participants. RESULTS: We found that regular IMT in subjects with cervical SCI significantly improved forced vital capacity (means +/- SE) (11% +/- 2.82% increase), forced inspiratory vital capacity (21% +/- 6.91%), vital capacity (8% +/- 4.36%), total lung capacity (12% +/- 3.23%), functional residual capacity (15% +/- 5.96%), and MIP (24% +/- 6.98%) (p < .05). Furthermore, although no statistical differences were observed for the dyspnea scale, the fact that subjects reported decreased levels (43% +/- 21.30% reduction) of perceived difficulty breathing may be of greater importance. No significant differences from baseline values were found in the seven subjects whose spirometry and respiratory muscle strength were measured 6 months after the study. CONCLUSIONS: Our findings suggest that in individuals with cervical SCI regular resistive IMT may result in decreased restrictive ventilatory impairment and reported dyspnea and, thus, reduced incidence of chronic respiratory complaints, respiratory infection, and other pulmonary complications.

Adult↗

PubMed1984

Calculation of lung volume in newborn infants by means of a computer-assisted nitrogen washout method.

A clinically adapted method for the calculation of the functional residual capacity in newborn infants has been developed. The method is based on a multiple breath nitrogen washout test, during which the ventilatory air flow and the nitrogen concentration signals are sampled by a minicomputer, which also performs the calculations. The ventilatory air flow is measured by a pneumotachometer connected to a face-out volume displacement body plethysmograph, and the nitrogen concentration by a nitrogen analyzer. The functional residual capacity volume is calculated from the sampled signals by adding the expired nitrogen volumes during each expiration, and finally dividing this sum by the initial alveolar nitrogen concentration. Before the calculations, the sampled signals are adjusted regarding nitrogen analyzer delay and plethysmograph characteristics. The method presented is designed to minimize the test equipment influence on the baby's respiration and also to inhibit the necessity of pneumotachometer compensations normally connected with washout methods. Furthermore, the calculated breath-by-breath values of end-expiratory nitrogen concentration, nitrogen volume, inspired and expired tidal volume, are stored on disk for further analysis and resimulation of the test. The method has been tested on a mechanical lung model and on washouts from healthy newborn infants. The model tests indicate that the accuracy and the reproducibility of the method are good, and the results from the infants are in good agreement with previously obtained results.

Computers↗

PubMed1995

Cardiopulmonary function in premature infants with bronchopulmonary dysplasia--a 2-year follow up.

Twenty-three premature infants (GA 28.8 +/- 0.5 weeks) with bronchopulmonary dysplasia (BPD) and 14 premature infants (controls, GA 33.0 +/- 1.2 weeks) with moderate respiratory distress syndrome or with mild respiratory disturbances, were evaluated for impairment of cardiopulmonary function at 50 and 120 weeks corrected age. Respiratory system compliance was reduced in both groups, but improved with advancing age. Respiratory system resistance was initially increased, especially in the BPD group, but improved gradually. Maximum flow at functional residual capacity (VmaxFRC ml/s) indicated, nevertheless, severe peripheral obstruction (flow < 84 ml/s) in 16/20 of infants with BPD and in 7/12 of control infants at 50 weeks corrected age. At 120 weeks corrected age none of the control patients had severe peripheral pulmonary obstruction (flow < 120 ml/s), while this was still found in 5/13 infants with BPD. Doppler echocardiography indicated cardiac involvement (shortened pulmonary acceleration time) in patients with the most severe peripheral pulmonary obstruction. Pulmonary morbidity was also higher in the BPD group, and these infants were shorter and weighed less than the control infants. CONCLUSION. Measurements of maximum flow at functional residual capacity as well as cardiac evaluation are essential elements in follow up of infants with severe BPD.

Airway Resistance↗

PubMed2001

Ventilatory responses to hypercapnia in divers and non-divers: effects of posture and immersion.

The aim of this study was to determine the effects on respiratory drive of two factors, one mechanical (lung volume) and one chemical (sensitivity to hypercapnia), that are involved in determining the breath-hold duration (BHD). Functional residual capacity was measured by helium dilution with the subject seated in air, seated in water and in the prone position in water. Hyperoxic hypercapnia rebreathing (Read's method) was carried out under identical environmental conditions to assess the effects of CO2 pressure on respiratory centre output by measuring ventilation, mean inspiratory flow and occlusion pressure. Sixteen healthy volunteers were tested. 8 trained divers and 8 non-divers. Functional residual capacity decreased for the postures seated in water (30.8%-34.8%) and for prone position in water (20.3%-20.9%) when compared to the posture seated in air (P<0.0001), all subjects pooled. No difference was found between groups. The slopes of the linear regression, which characterised the sensitivity to CO2 and were determined with the rebreathing tests, revealed differences between the two populations (ventilation: P < 0.0001; mean inspiratory flow: P < 0.05). No difference was found for occlusion pressure or between the different postures. These results confirmed a lower sensitivity to CO2 for trained divers. This adaptation was shown to decrease respiratory centre activity at the origin of the breath-hold breaking point. The immersion, did not influence respiratory drive, despite a decrease in lung volumes. The authors suggest that these findings may be explained by a specific apnoea training and a pronounced bradycardia in immersion.

Adaptation, Physiological↗

PubMed1995

Lung volume and pulmonary blood flow measurements following exogenous surfactant.

UNLABELLED: Lung function in eight infants with clinical and radiological features of surfactant deficiency treated with exogenous porcine surfactant was studied before and at 15 min, 2h and 6h after the intratracheal administration of porcine surfactant. We measured alveolar-arterial oxygen tension difference, dynamic lung compliance, lung volume and effective pulmonary blood flow in all infants. The alveolar-arterial oxygen tension difference fell from a mean (SD) 43.3 (14.5) kPa before treatment to 8.8 (8.8) kPa at 1 h and 12.2 (6.8) kPa 6h after treatment (P < 0.001). There was no change in mean (SD) dynamic compliance (0.39 [0.10] ml/cmH2O/kg pre dose; 0.36 [0.13] ml/cmH2O/kg 6h post treatment). Accessible functional residual capacity and effective pulmonary blood flow were measured using an adaptation of the argon/freon rebreathing method and showed an increase in mean (SD) functional residual capacity from 7.5 (1.4) ml/kg predose to 10.8 (3.3) ml/kg within 15 min of treatment, 11.4 (3.4) ml/kg 2h later and 12.7 (3.1) ml/kg 6h after treatment (P = 0.009). Mean (SD) effective pulmonary blood flow values did not differ significantly, changing from 78.2 (20.9) ml/kg per min predose to 88.7 (24.1) ml/kg per min 15 min post dose, 87.6 (21.7) ml/kg per min 2h post dose and 90.0 (22.7) ml/kg per min 6h post dose (P = 0.711). CONCLUSION: The improvement in oxygenation after surfactant treatment is associated with an increase in lung volume but is not related to an improvement in dynamic lung compliance or effective pulmonary blood flow. The change in lung volume is detectable within 15 min of administration of the surfactant.

Analysis of Variance↗

PubMed2000

Prediction of extubation failure in preterm neonates.

UNLABELLED: The aim of this study was to compare the results of lung function measurements made before and after extubation and ventilator settings recorded immediately prior to extubation with regard to their ability to predict extubation success in mechanically ventilated, prematurely born infants. Immediately after extubation all infants were nursed in an appropriate amount of humidified oxygen bled into a headbox. Functional residual capacity, spontaneous tidal volume and compliance of the respiratory system were measured both within 4 h before and within 24 h after extubation. The peak inspiratory pressure and inspired oxygen concentration immediately prior to extubation were recorded. The results were related to extubation failure: requirement for continuous positive airways pressure or re-ventilation within 48 h of extubation. A total of 30 infants, median gestational age 29 weeks (range 25-33 weeks) were studied at a median postnatal age of 3 days (range 1-6 days). Extubation failed in ten infants, who differed significantly from the rest of the cohort with regard to their post extubation functional residual capacity (FRC) (median 23, range 15.6-28.7 ml/kg versus 28.6, range 18.1-39.2 ml/kg, P<0.01) and their requirement for a higher inspired oxygen concentration post extubation (median 0.30, range 0.21-0.40 versus 0.22, range 0.21-0.36, P<0.05). An FRC of less than 26 ml/kg post extubation had the highest positive predictive value in predicting extubation failure. CONCLUSION: A low lung volume performed best in predicting extubation failure when compared to the results of other lung function measurements and commonly used 'clinical' indices, i.e. ventilator settings. A low gestational age, however, was a better predictor of extubation failure than a low lung volume.

Functional Residual Capacity↗

PubMed1994

Changes in end-expiratory lung volume on induction of anaesthesia with thiopentone or propofol.

To determine the effects of induction agent and obesity on the change in functional residual capacity caused by induction of anaesthesia, we measured the change in end-expiratory respiratory volume (EERV) during induction of anaesthesia with either thiopentone or propofol. Female patients breathed via a face mask from a closed circle system connected to a water spirometer. The spirometer tracing was used to measure the decrease in EERV. The median decrease was 200 (95% confidence limits 90-280) ml after thiopentone and 285 (200-425) ml after propofol. The decrease in each group was significant (P < 0.01) but there was no difference between the two groups. The change in EERV, expressed as a proportion of the predicted functional residual capacity, was not related to obesity (estimated as the ratio of actual to predicted body weight).

Adult↗

PubMed1978

Pulmonary physiotherapy in neonates: physiologic changes and respiratory management.

To investigate physiologic alterations in respiratory function associated with chest physiotherapy, arterial blood gases, respiratory patterns, lung mechanics, and functional residual capacity were measured in 13 neonates (weights 1.25 to 3.20 kg) during the control period, after vibration of the chest and suctioning, after hyperventilation, and two hours after suctioning. Compared to control values, mean PO2decreased significantly after suctioning to 43 mm Hg and increased significantly after hyperventilation to 78 mm Hg. There was a significant decrease in inspiratory resistance and a trend toward decrease in expiratory resistance after suctioning, with return to control levels after hyperventilation. Respiratory rate increased significantly after suctioning. Functional residual capacity, dynamic lung compliance, and tidal volume, as well as PCO2 and base excess, were not changed appreciably throughout the protocol. Because of potentially severe hypoxemia, this study suggests that suctioning and hyperventilation are not warranted on a routine basis in infants recovering from respiratory diseases.

Carbon Dioxide↗

PubMed2000

Factors determining the onset and course of hypoxemia during apnea: an investigation using physiological modelling.

UNLABELLED: We used the Nottingham Physiology Simulator to examine the onset and course of hypoxemia during apnea after pulmonary denitrogenation. The following factors, as possible determinants of the hypoxemia profile, were varied to examine their effect: functional residual capacity, oxygen consumption, respiratory quotient, hemoglobin concentration, ventilatory minute volume, duration of denitrogenation, pulmonary venous admixture, and state of the airway (closed versus open). Airway obstruction significantly reduced the time to 50% oxyhemoglobin saturation (8 vs 11 min). Provision of 100% oxygen rather than air to the open, apneic patient model greatly prolonged time to 50% oxyhemoglobin saturation (66 vs 11 min). Hemoglobin concentration, venous admixture, and respiratory quotient had small, insignificant effects on the time to desaturation. Reduced functional residual capacity, short duration of denitrogenation, hypoventilation, and increased oxygen consumption significantly shortened the time to 50% oxyhemoglobin saturation during apnea. IMPLICATIONS: Reduction in oxygen levels during cessation of breathing is dangerous and common in anesthetic practice. We used validated, mathematical, physiological models to reveal the impact of physiological factors on the deterioration of oxygen levels. This study could not be performed on patients and reveals important information.

Apnea↗

PubMed1998

Liquid ventilation innovations in ventilatory management.

The goal of mechanical ventilation is to maintain adequate gas exchange by opening and stabilizing alveolar units with minimal detriment to the pulmonary and circulatory systems. The optimal ventilatory strategy may be difficult to achieve, especially in patients with respiratory failure. Total liquid ventilation is a process whereby a liquid perfluorocarbon (PFC) replaces both the functional residual capacity and the tidal volume within the lung. Gas exchange is accomplished by mechanically assisted inspiration and expiration of tidal volumes of the liquid using a liquid ventilator. The PFC liquid is then oxygenated and purged of carbon dioxide by a membrane lung. Perfluorocarbons are excellent media for gas exchange due to their extraordinary gas solubility and diffusibility of oxygen and carbon dioxide. Partial liquid ventilation (PLV) is a modified method of the total liquid ventilation technique. In PLV, a functional residual capacity of PFC liquid is maintained in the lung, and the patient is ventilated with a conventional gas mechanical ventilator. Studies of the acute respiratory distress syndrome in animal models and in human series have demonstrated encouraging results using PLV and PFC. The high density, low surface tension, and other qualities of PFC in the setting of PLV may offer a highly innovative approach that can be directed toward the management of patients in respiratory failure.

Animals↗

PubMed1991

Diaphragmatic electromyogram power-spectral analysis as a function of reduced end-expiratory lung volume.

We examined the centroid frequency (Fc) of the electromyogram power-frequency spectra from the costal (EMGco) and crural (EMGcr) diaphragms at functional residual capacity and at reduced end-expiratory lung volume (EELV) (induced by abdominal banding) in six anesthetized newborn piglets. EMGco and EMGcr were recorded from bipolar electrodes embedded in the costal and crural diaphragms respectively. A fast Fourier transformation of ECG free EMGco and EMGcr was used to compute the power-frequency spectra and calculate the Fc of EMGco and EMGcr. The nitrogen washout technique was used to measure EELV. Abdominal banding induced a reduction in EELV of 30.6% functional residual capacity (range 22-39%). The mean Fc of EMGcr was not significantly altered by the reduction in EELV, whereas the mean Fc of the EMGco fell in every animal at reduced EELV by 13 +/- 8% of baseline Fc (p less than 0.05). We conclude that alterations in lung volume alone can determine changes in the EMGco power spectrum and Fc. Investigators performing EMGco power spectral analysis should consider EELV status when interpreting their findings.

Animals↗